WO2018193986A1 - Solid-state imaging element and method for manufacturing same - Google Patents

Abstract

Provided is a solid-state imaging element including a color filter layer of which the optical reception sensitivity is optimized for each of red, green, and blue pixels. The solid-state imaging element includes an undercoating layer (7) between a planarization layer (3) and a color filter layer (4). The undercoating layer (7) is formed to a thickness such that: the focal point of a microlens (5) in a red filter pixel portion is at a position of not less than 2000 nm and not more than 2500 nm from an boundary surface of a photoelectric convert element (2) with respect to the planarization layer (3); the focal point of the microlens (5) at a green filter pixel portion is at a position of not less than 600 nm and not more than 900 nm from a boundary surface of the photoelectric convert element (2) with respect to the planarization layer (3); and the focal point of the microlens (5) at a blue filter pixel portion is at a position of not less than 200 nm and not more than 500 nm from a boundary surface of the photoelectric convert element (2) with respect to the planarization layer (3).

Description

Solid-state imaging device and manufacturing method thereof

The present invention relates to a solid-state imaging device and a manufacturing method thereof.

In recent years, imaging devices have been widely used with the expansion of the contents of image recording, communication, and broadcasting. Various types of image pickup devices have been proposed. An image pickup device incorporating a solid-state image pickup device that has been stably manufactured with a small size, light weight, and high performance can be used as a digital camera or digital video. It has become widespread.
The solid-state imaging device has a plurality of photoelectric conversion elements that receive an optical image from a subject and convert incident light into an electrical signal. The types of photoelectric conversion elements are roughly classified into CCD types and C-MOS types. Further, two types of arrangements of the photoelectric conversion elements, a linear sensor (line sensor) in which the photoelectric conversion elements are arranged in one row and an area sensor (surface sensor) in which the photoelectric conversion elements are two-dimensionally arranged vertically and horizontally. It is divided roughly into. In any of the sensors, as the number of photoelectric conversion elements (number of pixels) increases, the captured image becomes more precise. In recent years, in particular, a method for manufacturing a solid-state imaging element having a large number of pixels at low cost has been studied.

In addition, a color filter that transmits light of a specific wavelength is provided in the upper layer of the photoelectric conversion element in the path of light incident on the photoelectric conversion element. The color filter layer can collect color-separated image information by patterning one pixel by a specific colored transparent pixel corresponding to one photoelectric conversion element and regularly arranging a plurality of pixels. As a color of the colored transparent pixel, for example, three primary colors composed of three colors of red (R), green (G), and blue (B) are often used.
In the upper layer of the color filter layer, microlenses corresponding to each pixel are provided in a uniform shape. The light condensed by the microlens is configured to enter the photoelectric conversion element through the color filter layer. By condensing the light with the microlens and guiding it to the light receiving portion of the photoelectric conversion element, the apparent aperture ratio of the light receiving portion can be increased, and the sensitivity of the solid-state imaging device can be improved.

One of the important issues in performance required for a solid-state imaging device is to improve the sensitivity to incident light. In order to increase the amount of information of an image photographed with a miniaturized solid-state imaging device, it is necessary to miniaturize and highly integrate a photoelectric conversion device serving as a light receiving unit. However, when the photoelectric conversion elements are highly integrated, the area of each photoelectric conversion element is reduced, and the area ratio that can be used as the light receiving part is also reduced. Therefore, the amount of light that can be taken into the light receiving part of the photoelectric conversion element is reduced, which Sensitivity is reduced.
In addition, in the color filter layer of the solid-state image sensor, one pixel is formed by patterning in red (R), green (G), and blue (B), but there is a problem that the sensitivity of the solid-state image sensor varies depending on each pixel. The transmittance to the inside of the solid-state image sensor varies depending on the wavelength of each color of the color filter layer. For example, blue (B) is absorbed near the surface of the solid-state image sensor, but red (R) is transmitted to the inside of the solid-state image sensor. Therefore, a sensitivity difference is generated due to a difference in light transmittance of each color of the color filter layer.

In Patent Document 1, the first color filter layer formed first on the planarization layer formed on the plurality of photoelectric conversion elements has a surface free energy larger than that of the planarization layer and a film thickness of 100 nm or less. It is described that color filter layers other than the first color filter layer are formed on the flattening layer. Thus, it is described that a color filter layer that is miniaturized and thinned in accordance with the progress of pixel miniaturization can be formed with few defects such as residue and peeling.

JP-A-2016-225338

An object of the present invention is to provide a solid-state imaging device having a color filter layer in which light receiving sensitivity is optimized for each of red (R), green (G), and blue (B) pixels.

A solid-state imaging device according to a first aspect of the present invention includes a semiconductor substrate, and a plurality of photoelectric conversion elements formed on the semiconductor substrate, the photoelectric conversion elements arranged in a matrix in the plane of the semiconductor substrate, A planarization layer formed on the semiconductor substrate so as to cover the plurality of photoelectric conversion elements, an undercoat layer formed on the planarization layer, and a color filter layer formed on the undercoat layer, A plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements, a color filter layer having a red (R) filter, a green (G) filter, and a blue (B) filter, and the plurality of color filters; And a plurality of microlenses formed respectively. In the undercoat layer, the focal point of the microlens in the pixel portion of the red (R) filter is at a position of 2000 nm to 2500 nm from the boundary surface with the planarization layer of the photoelectric conversion element, and the pixel of the green (G) filter The focal point of the microlens at the portion is 600 nm to 900 nm from the boundary surface with the planarization layer of the photoelectric conversion element, and the focal point of the microlens at the pixel portion of the blue (B) filter is the flatness of the photoelectric conversion element. The film is formed with a thickness that is 200 nm or more and 500 nm or less from the boundary surface with the conversion layer.

Further, in the method for manufacturing a solid-state imaging device according to the second aspect of the present invention, the semiconductor substrate is formed so as to cover the plurality of photoelectric conversion elements formed on the semiconductor substrate and arranged in a matrix in the plane of the semiconductor substrate. A flattening layer forming step for forming a flattening layer thereon, an undercoat layer forming step for forming an undercoat layer on the flattening layer, and a plurality of photoelectric conversion elements arranged in the same matrix on the undercoat layer A color filter layer forming step of forming a color filter layer comprising a plurality of color filters and having a red (R) filter, a green (G) filter, and a blue (B) filter, and a plurality of color filters on the plurality of color filters And a microlens forming step for forming each microlens. The undercoat layer forming step is performed by forming a liquid layer containing a transparent photosensitive resin on the planarizing layer and then photocuring the liquid layer by a photolithography method using a gray tone mask. The thickness of the undercoat layer immediately below the red (R) filter is set so that the focal point of the microlens in the pixel portion of the red (R) filter is 2000 nm or more and 2500 nm from the boundary surface with the planarization layer of the photoelectric conversion element. The thickness is as follows. The thickness of the undercoat layer immediately below the green (G) filter is set so that the focal point of the microlens in the pixel portion of the green (G) filter is 600 nm or more and 900 nm from the boundary surface with the planarization layer of the photoelectric conversion element. The thickness is as follows. The thickness of the undercoat layer immediately below the blue (B) filter is set so that the focal point of the microlens in the pixel portion of the blue (B) filter is 200 nm or more and 500 nm from the boundary surface with the planarization layer of the photoelectric conversion element. The thickness is as follows.

The solid-state imaging device according to the third aspect of the present invention includes a semiconductor substrate and a plurality of photoelectric conversion elements formed on the semiconductor substrate, the photoelectric conversions being arranged in a matrix within the surface of the semiconductor substrate. An element, a planarization layer formed on the semiconductor substrate so as to cover the plurality of photoelectric conversion elements, an undercoat layer formed on the planarization layer, and a color filter layer formed on the undercoat layer. The color filter includes a plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements, and includes a red (R) filter, a green (G) filter, a blue (B) filter, and an infrared (IR) filter. A layer, and a plurality of microlenses formed on the plurality of color filters, respectively. In the undercoat layer, the focal point of the microlens in the pixel portion of the red (R) filter is a position of 2000 nm to 2500 nm from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side, and green ( G) The focal point of the micro lens in the pixel portion of the filter is a position of 600 nm to 900 nm from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side, and the micro lens in the pixel portion of the blue (B) filter The focal point of the lens is a position of 200 nm or more and 500 nm or less from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side, and the focal point of the microlens in the pixel portion of the infrared (IR) filter is It is formed with a thickness that is 1500 nm or more and 5000 nm or less from the boundary surface with the planarization layer to the photoelectric conversion element side.

The solid-state imaging device manufacturing method according to the fourth aspect of the present invention includes a semiconductor substrate formed on a semiconductor substrate so as to cover a plurality of photoelectric conversion elements arranged in a matrix within the surface of the semiconductor substrate. A flattening layer forming step for forming a flattening layer thereon, an undercoat layer forming step for forming an undercoat layer on the flattening layer, and a plurality of photoelectric conversion elements arranged in the same matrix on the undercoat layer A color filter layer forming step of forming a color filter layer comprising a plurality of color filters and having a red (R) filter, a green (G) filter, a blue (B) filter, and an infrared (IR) filter; A microlens forming step of forming a plurality of microlenses on the color filter. The undercoat layer forming step is performed by forming a liquid layer containing a transparent photosensitive resin on the planarizing layer and then photocuring the liquid layer by a photolithography method using a gray tone mask. The thickness of the undercoat layer immediately below the red (R) filter is set so that the focal point of the microlens in the pixel portion of the red (R) filter is from the boundary surface with the planarization layer of the photoelectric conversion element. The thickness is set to a position of 2000 nm to 2500 nm toward the side. The thickness of the undercoat layer immediately below the green (G) filter is set so that the focal point of the microlens in the pixel portion of the green (G) filter is from the boundary surface with the planarization layer of the photoelectric conversion element. The thickness is 600 nm or more and 900 nm or less to the side. Then, the thickness of the undercoat layer immediately below the blue (B) filter is set so that the focal point of the microlens in the pixel portion of the blue (B) filter is from the boundary surface with the planarization layer of the photoelectric conversion element. The thickness is set to be 200 nm or more and 500 nm or less to the side. The thickness of the undercoat layer immediately below the infrared (IR) filter is set so that the focal point of the microlens in the pixel portion of the infrared (IR) filter is from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side. The thickness is set to a position of 1500 nm to 5000 nm.

Further, in the solid-state imaging device (image sensor) according to the fifth aspect of the present invention, at least a photoelectric conversion element and a microlens are stacked in this order on a semiconductor substrate, and each unit photoelectric conversion element has green, Blue and red pixels are formed, the microlens height on the green pixel is 100%, the microlens height on the blue pixel is in the range of 105% to 150%, and on the red pixel The microlens height is in the range of 95% to 70%.

In the solid-state imaging device (image sensor) according to the sixth aspect of the present invention, at least a photoelectric conversion element, a planarization layer, a color separation filter, and a microlens are stacked in this order on a semiconductor substrate. For each photoelectric conversion element as a unit, either a green pixel, a blue pixel, or a red pixel is formed, and a microlens of a green pixel corresponding to each of the green pixel, the blue pixel, and the red pixel, A blue pixel microlens and a red pixel microlens are formed, and the focal depth of the blue pixel microlens is 200 nm or more and 500 nm or less from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side. The focal depth of the green pixel microlens is the same as that of the planarization layer of the photoelectric conversion element. The focal depth of the red lens microlens is 2000 nm or more and 2500 nm or less from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side at a position of 600 nm to 900 nm from the boundary surface to the photoelectric conversion element side. It is in position.

A solid-state imaging device (image sensor) manufacturing method according to the seventh aspect of the present invention is a method for manufacturing the solid-state imaging device according to the fifth or sixth aspect of the present invention. The microlenses having different heights are collectively formed by a photolithography method using the above.

According to the present invention, there is provided a solid-state imaging device having a color filter layer in which the light receiving sensitivity is optimized for each of red (R), green (G), and blue (B) pixels.

It is a top view which shows arrangement | positioning of the color filter and photoelectric conversion element which comprise the solid-state image sensor which concerns on Embodiment 1 of this invention. 2A and 2B are cross-sectional views illustrating the solid-state imaging device according to the first embodiment of the present invention, where FIG. 1A is a cross-sectional view taken along line II in FIG. 1, FIG. 1B is a cross-sectional view taken along line II-II in FIG. It is a figure corresponding to the III-III section. It is a figure explaining the difference in the focus of the micro lens in a pixel part by the difference in the color of the color filter in a general solid-state image sensor. It is a graph which shows the relationship between ML depth (distance from the photoelectric conversion element surface of the focus of a micro lens) and light reception sensitivity for every color of a color filter. It is sectional drawing explaining the manufacturing method of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a top view which shows arrangement | positioning of the color filter and photoelectric conversion element which comprise the solid-state image sensor which concerns on Embodiment 2 of this invention. 7 is a cross-sectional view showing a solid-state imaging device according to Embodiment 2 of the present invention, where (a) is a cross-sectional view taken along line IV-IV in FIG. 6, (b) is a cross-sectional view taken along line VV in FIG. It is a figure corresponding to a VI-VI cross section. It is sectional drawing explaining the manufacturing method of the solid-state image sensor which concerns on Embodiment 2 of this invention. It is a top view which shows arrangement | positioning of the color filter and photoelectric conversion element which comprise the solid-state image sensor which concerns on Embodiment 3 of this invention. 9A and 9B are cross-sectional views illustrating a solid-state imaging device according to Embodiment 3 of the present invention, where FIG. 9A is a cross-sectional view taken along line VII-VII in FIG. 9, FIG. 9B is a cross-sectional view taken along line XIII-XIII in FIG. It is a figure corresponding to the IX-IX section. It is a figure explaining the micro lens focus difference in the pixel part by the difference in the color of the color filter in a general solid-state image sensor. It is a graph which shows the relationship between the focal depth of ML (distance from the photoelectric conversion element surface of the focus of a micro lens) and light reception sensitivity for every color of a color filter. It is sectional drawing explaining the manufacturing method of the solid-state image sensor which concerns on Embodiment 3 of this invention. It is typical sectional drawing explaining the structure of the image sensor (solid-state image sensor) which concerns on Embodiment 4 of this invention. It is a typical fragmentary top view explaining each pixel arrangement | positioning of red, green, and blue in the image sensor of FIG. It is a graph which shows an example of the light reception sensitivity curve explaining the light reception sensitivity of each pixel of red, green, and blue in a general image sensor. It is a figure explaining one Embodiment of the gray tone mask used for the photolithographic method which concerns on this invention. It is a typical sectional view of an image sensor explaining light reception depth of red, green, and blue in a general image sensor. FIG. 15 is a schematic partial cross-sectional view (XX cross-sectional view in FIG. 15) illustrating a microlens arranged on each of red and green pixels of the image sensor of FIG. FIG. 15 is a schematic partial cross-sectional view (a YY cross-sectional view in FIG. 15) illustrating a microlens arranged on each of green and blue pixels of the image sensor of FIG. FIG. 10 is a schematic partial cross-sectional view ((a) to (d)) for explaining an eighth example of the image sensor manufacturing method according to the fourth embodiment of the present invention. FIG. 10 is a schematic partial cross-sectional view ((a) to (e)) for explaining an example 8 of the image sensor manufacturing method according to the fourth embodiment of the present invention. FIG. 10 is a schematic partial cross-sectional view ((a) to (d)) for explaining Example 9 of the method for manufacturing the image sensor according to the fourth embodiment of the present invention. FIG. 10 is a schematic partial cross-sectional view ((a) to (e)) for explaining Example 9 of the method of manufacturing the image sensor according to the fourth embodiment of the present invention. It is an example of the AFM observation image of the micro lens created with the manufacturing method of the image sensor which concerns on Embodiment 4 of this invention. It is the figure ((a), (b)) which graphed the content of Table 4 which contrasts the microlens height of the microlens produced with the manufacturing method of the image sensor which concerns on Embodiment 4 of this invention, and light reception sensitivity. It is a figure explaining the 1st gray tone mask and 2nd gray tone mask which concern on Embodiment 5 of this invention. It is a figure ((1)-(5)) explaining the manufacturing method of the micro lens which concerns on Embodiment 5 of this invention. It is typical sectional drawing explaining the structure of the image sensor which concerns on Embodiment 6 of this invention. FIG. 30 is a schematic partial plan view for explaining each pixel arrangement of red, green, and blue in the image sensor of FIG. 29. It is a graph which shows an example of the light reception sensitivity curve explaining the light reception sensitivity of each pixel of red, green, and blue in an image sensor. FIG. 10 is a schematic cross-sectional view of an image sensor according to Embodiment 6 for explaining red, green, and blue light receiving depths. It is the figure which made the content of Table 5 the graph which contrasted the microlens height of the microlens produced with the manufacturing method of the image sensor of Embodiment 6, and light reception sensitivity.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. In the embodiment described below, a technically preferable limitation is made for carrying out the present invention, but this limitation is not an essential requirement of the present invention.

(Embodiment 1)
<Configuration>
As shown in FIGS. 1 and 2, the solid-state imaging device 6 of Embodiment 1 includes a photoelectric conversion element 2, a planarization layer 3, an undercoat layer 7, and a plurality of color filters 4 </ b> R and 4 </ b> G on a semiconductor substrate 1. , 4B and the microlens 5 are laminated in this order. In FIG. 2, other components of the solid-state imaging device 6 are omitted for easy understanding of the arrangement of the photoelectric conversion elements 2 and the color filters.

On the semiconductor substrate 1, photoelectric conversion elements 2 made of CMOS or CCD are formed in a matrix as light receiving elements. A silicon oxide film or a silicon nitrogen oxide film (not shown) is formed on the surface of the semiconductor substrate 1, and a planarizing layer 3 made of a transparent resin is formed on the semiconductor substrate 1. On the planarizing layer 3, an undercoat layer 7 made of a transparent resin is formed with an appropriate film thickness corresponding to each pixel. Further, a color filter layer 4 made of a transparent resin in which a coloring material such as a pigment or a dye is dispersed is formed on the undercoat layer 7. The color filter layer 4 of the first embodiment includes a red (R) filter 4R and a green (G) filter that respectively transmit one of the three colors red (R), green (G), and blue (B). A 4G and blue (B) filter 4B is provided, and these three colors are arranged in a Bayer array. The pixel arrangement and the color of the color filter constituting the color filter layer 4 are not limited to these. The color combination may be a combination in which color filters such as yellow and transparent are provided in addition to the three primary colors. On these color filter layers 4, microlenses 5 are formed corresponding to the photoelectric conversion elements 2.

As shown in FIG. 3, when the red (R) filter 4R, the green (G) filter 4G, and the blue (B) filter 4B have the same film thickness and are not provided with the undercoat layer 7, they are incident on the microlens 5. The light passes through each filter and is focused at different positions in the thickness direction of the photoelectric conversion element 2.
Specifically, light with a red (R) wavelength passes through the photoelectric conversion element relatively deeply to about 2000 nm. Accordingly, in the red (R) pixel region, it is desirable that the focal position of the microlens 5 is a position 8c in the photoelectric conversion element layer. FIG. 4 shows the light receiving sensitivity when the focal point of the microlens 5 is changed in a range where the distance from the surface of the red (R) photoelectric conversion element (boundary surface with the planarization layer) is 0 nm or more and 3500 nm or less. . From FIG. 4, it can be seen that, under the red (R) pixel, the light receiving sensitivity reaches a peak in a range where the focal point of the microlens 5 is in a range of 2000 nm to 2500 nm from the photoelectric conversion element surface.

Light of green (G) wavelength is transmitted to a depth of about 600 nm of the photoelectric conversion element. In accordance with this, in the green (G) pixel region, it is desirable that the focal position is the position 8b in the photoelectric conversion element layer. FIG. 4 shows the light receiving sensitivity when the focal point of the microlens 5 is changed in a range where the distance from the surface of the green (G) photoelectric conversion element is 0 nm or more and 1500 nm or less. From FIG. 4, it can be seen that under the green (G) pixel, the light receiving sensitivity reaches a peak in a range where the focal point of the microlens 5 is 600 nm or more and 900 nm or less from the surface of the photoelectric conversion element.

Blue (B) wavelength light is transmitted to a depth of about 200 nm near the surface of the photoelectric conversion element. Accordingly, in the blue (B) pixel region, it is desirable that the focal position is a position 8a in the vicinity of the surface of the photoelectric conversion element. FIG. 4 shows the light receiving sensitivity when the focal point of the microlens 5 is changed in a range where the distance from the surface of the blue (B) photoelectric conversion element is 0 nm or more and 1500 nm or less. From FIG. 4, it can be seen that, under the blue (B) pixel, the light receiving sensitivity reaches a peak in a range where the focal point of the microlens 5 is in the range of 200 nm to 500 nm from the surface of the photoelectric conversion element.

From the above, in the solid-state imaging device of the first embodiment, the focal point of the microlens 5 is a distance from the surface of the photoelectric conversion element, and is in the range of 2000 nm to 2500 nm below the red (R) pixel, green (G). The thickness of the undercoat layer 7 provided between the planarizing layer 3 and the color filter layer 4 so as to be in the range of 600 nm to 900 nm under the pixel and in the range of 200 nm to 500 nm under the blue (B) pixel. Is set for each pixel. The transmittance of the undercoat layer 7 is 90% or more in the wavelength range of 300 nm to 800 nm.

In addition, as shown in FIG. 2, the color filter is obtained by changing the thickness of the red (R) filter 4R, the green (G) filter 4G, and the blue (B) filter 4B according to the thickness of the undercoat layer 7. The surface of the layer 4 on the microlens 5 side is preferably a flat surface. This is because the microlens 5 can be easily formed because there is no step between the color filters of adjacent colors or there are few steps. In order to reduce the level difference between the color filters, a planarization layer may be added on the color filters.
Here, the vertices 5a of the microlenses on the red (R), green (G), and blue (B) color filter layers 4 have substantially the same height. As a result, the distribution of incident light to red, green, and blue pixels can be easily controlled, and the sensitivity of the solid-state imaging device 6 can be stably changed according to the focal depth of the microlens 5.

<Manufacturing method>
Next, with reference to FIG. 5, the manufacturing method of the solid-state image sensor 6 of Embodiment 1 will be described.
First, a semiconductor substrate 1 in which a plurality of photoelectric conversion elements 2 are arranged in a matrix in a plane is prepared, and a planarization layer 3 is formed on the semiconductor substrate 1 so as to cover the plurality of photoelectric conversion elements 2. After this planarization layer stacking step, an undercoat layer corresponding to each pixel is formed.
In the undercoat layer forming step, first, as shown in FIG. 5A, a liquid (photoresist) containing a transparent photosensitive transparent resin is applied to the planarizing layer 3 with a predetermined thickness, and the liquid layer 70 is formed. Form. Next, as shown in FIGS. 5B and 5C, the liquid layer 70 is exposed, developed, and baked based on the photolithography method using the gray tone mask 9, thereby subtracting. Layer 7 is formed.

In this undercoat layer forming step, the transmissivity of the gray tone mask is changed at each position of the red (R) filter, the green (G) filter, and the blue (B) filter, so that in the plane of the undercoat layer 7. Is controlled so that the focal point of the microlens 5 under each pixel falls within the above-described range.
In this step, it is easy to control the thickness within the surface of the undercoat layer 7 by using the gray tone mask 9 that can arbitrarily change the mask transmittance gradation. The gradation of the mask transmittance gradation is achieved by a partial difference in density per unit area of small diameter dots that are not resolved by light used for exposure.

After the undercoat layer is formed, a plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements 2 on the undercoat layer, that is, a red (R) filter 4R, a green (G) filter 4G, and a blue color (B) The color filter layer 4 composed of the filter 4B is formed. After this color filter layer forming step, a microlens forming step of forming a plurality of microlenses 5 on the plurality of color filters, respectively. These steps can be performed by applying a conventionally known photolithography method, etching method, printing method, or the like. In particular, it is preferable to use a gray-tone mask that can arbitrarily change the mask transmittance gradation because the vertex 5a of the microlens can be easily controlled.

Hereinafter, examples and comparative examples will be described.
Example 1
The solid-state imaging device of Example 1 was produced by the following method.
A silicon wafer having a thickness of 0.75 mm and a diameter of 20 cm was used as the semiconductor substrate. A plurality of photodiodes made of CMOS as photoelectric conversion elements are arranged on the upper surface of the silicon wafer so as to form a Bayer array. Here, the arrangement period of the pixels of the photodiode was 1.1 μm.

Next, a film made of a styrene-based transparent resin was formed by spin coating, and baked at 200 ° C. for 2 minutes to form a planarization layer. The thickness of the planarizing layer was 40 nm.
Next, in forming the undercoat layer on the planarization layer, the microlens under the green (G) pixel is located at a position where the focal point of the microlens under the red (R) pixel is 2200 nm from the surface of the photoelectric conversion element. The film thickness of the undercoat layer is set so that the focal point of the microlens under the blue (B) pixel corresponds to the position of 300 nm from the surface of the photoelectric conversion element. did.

In the undercoat layer forming process, first, a positive resist made of an acrylic transparent resin having alkali solubility and photosensitivity is applied by spin coating to a thickness of 1.0 μm, and heated at 90 ° C. for 2 minutes to be hardened. Went. Thereafter, the acrylic transparent resin was exposed and developed by photolithography using a gray tone mask to form an undercoat layer. By using a gray tone mask, the film thickness of the undercoat layer in each pixel region was controlled. Thereafter, baking was performed at 180 ° C. for 2 minutes in a clean oven. The thickness of the undercoat layer in Example 1 was 32 nm under the red (R) pixel, 212 nm under the green (G) pixel, and 354 nm under the blue (B) pixel. The transmittance of the undercoat layer 7 was 97% in the wavelength range of 300 nm to 800 nm.

Next, a negative pigment dispersion resist having green (G) spectral characteristics was applied onto the undercoat layer by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel arrangement. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven.
Next, a negative pigment dispersion resist having red (R) spectral characteristics was applied by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven.

Next, a negative pigment dispersion resist having blue (B) spectral characteristics was applied by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven.
Next, a thermosetting acrylic resin layer having a flattening effect and containing an infrared absorber on the three color pixels of the color filter layer is applied by spin coating, and then cleaned at 200 ° C. in a clean oven. Then, a baking process was performed for 10 minutes to form a planarization layer. The film thickness was 0.5 μm.

Next, a microlens was formed on the color filter layer and the flattening layer. First, an acrylic transparent resin having alkali solubility and photosensitivity was applied by spin coating, and the film was hardened by heating at 90 ° C. for 2 minutes. Thereafter, microlenses were formed on the acrylic transparent resin by photolithography using a gray tone mask. By using the gray tone mask, the mask transmittance distribution in the pixel can be controlled, so that an arbitrary microlens shape can be formed.

(Example 2)
A solid-state imaging device of Example 2 was produced by the following method.
A silicon wafer having a thickness of 0.75 mm and a diameter of 20 cm was used as the semiconductor substrate. A plurality of photodiodes made of CMOS as photoelectric conversion elements are arranged on the upper surface of the silicon wafer so as to form a Bayer array. Here, the arrangement period of the pixels of the photodiode was 1.1 μm.
Next, a film made of a styrene-based transparent resin was formed by spin coating, and baked at 200 ° C. for 2 minutes to form a planarization layer. The thickness of the planarizing layer was 40 nm.
Next, when forming the undercoat layer on the planarization layer, the microlens under the red (R) pixel is located at a position 2400 nm from the surface of the photoelectric conversion element, and the microlens under the green (G) pixel. The film thickness of the undercoat layer is set so that the focal point of the microlens corresponds to the position of 850 nm from the surface of the photoelectric conversion element and the focal point of the microlens under the blue (B) pixel corresponds to the position of 2400 nm from the surface of the photoelectric conversion element. did.

In the undercoat layer forming step, first, a positive resist made of an alkali-soluble and photosensitive acrylic transparent resin is applied by spin coating to a thickness of 1.0 μm, and heated at 90 ° C. for 2 minutes to be hardened. Went. Thereafter, the acrylic transparent resin was exposed and developed by photolithography using a gray tone mask to form an undercoat layer. By using a gray tone mask, the film thickness of the undercoat layer in each pixel region was controlled. Thereafter, baking was performed at 180 ° C. for 2 minutes in a clean oven. In Example 2, the thickness of the undercoat layer was 22 nm under the red (R) pixel, 198 nm under the green (G) pixel, and 330 nm under the blue (B) pixel. The transmittance of the undercoat layer 7 was 97% in the wavelength range of 300 nm to 800 nm.

Next, a negative pigment dispersion resist having green (G) spectral characteristics was applied onto the undercoat layer by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel arrangement. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven.
Next, a negative pigment dispersion resist having red (R) spectral characteristics was applied by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven.

Next, a negative pigment dispersion resist having blue (B) spectral characteristics was applied by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven.
Next, a thermosetting acrylic resin layer having a flattening effect and containing an infrared absorber on the three color pixels of the color filter layer is applied by spin coating, and then cleaned at 200 ° C. in a clean oven. Then, a baking process was performed for 10 minutes to form a planarization layer. The film thickness was 0.5 μm.

Next, a microlens was formed on the color filter layer and the flattening layer. First, an acrylic transparent resin having alkali solubility and photosensitivity was applied by spin coating, and the film was hardened by heating at 90 ° C. for 2 minutes. Thereafter, microlenses were formed on the acrylic transparent resin by photolithography using a gray tone mask. By using the gray tone mask, the mask transmittance distribution in the pixel can be controlled, so that an arbitrary microlens shape can be formed.

(Comparative Example 1)
A solid-state imaging device of Comparative Example 1 was produced in the same manner as in Examples 1 and 2 except that the undercoat layer was not formed.
The light receiving efficiency of the solid-state imaging devices obtained in Example 1, Example 2 and Comparative Example 1 was measured. A value obtained by setting the light receiving efficiency of Comparative Example 1 to 100% was calculated as the light receiving sensitivity. These results are shown in Table 1.

From Table 1, in comparison with Comparative Example 1, the solid-state imaging device of Example 1 has a high light receiving sensitivity of about 5.4%, and the solid-state imaging device of Example 2 has a high light receiving sensitivity of about 4.9%. It turns out that the result was obtained.

(Embodiment 2)
A configuration of the solid-state imaging device 10 according to the second embodiment will be described with reference to FIGS. 6 and 7.
In addition, about the structure similar to Embodiment 1, the same code | symbol is used and the detail is abbreviate | omitted.

<Configuration>
As shown in FIGS. 6 and 7, the solid-state imaging device 10 according to the second embodiment includes a photoelectric conversion element 2, a planarization layer 3, and an adjacent photoelectric conversion element 2 on the semiconductor substrate 1 on a semiconductor substrate 1. The partition wall 11 is provided upright at a position corresponding to between the two. Further, the solid-state imaging device 10 includes an undercoat layer 7 formed between the adjacent partition walls 11 on the planarizing layer 3, a color filter layer 4 including a plurality of color filters 4R, 4G, and 4B, and a microlens. 5 are laminated in this order. In FIG. 6, other components of the solid-state imaging device 6 are omitted for easy understanding of the arrangement of the photoelectric conversion elements 2 and the color filters. The partition wall 11 has a lattice shape in plan view, and the color filter layer 4 is formed in the square opening of the partition wall 11.

The refractive index of the partition wall 11 is preferably 0.01 or more and 0.8 or less lower than the refractive index of the color filter layer 4, and particularly preferably 0.2 or more and 0.7 or less. Light traveling from the color filter layer 4 toward the partition wall 11 is easily reflected at the interface between the color filter layer 4 and the partition wall 11 having a lower refractive index, and does not easily enter the partition wall 11 and enter the adjacent color filter layer 4. By adopting a structure in which adjacent color filters are separated by partition walls, the light is unlikely to enter a photoelectric conversion element 2 different from the photoelectric conversion element 2 that should be incident, and color mixing can be reduced. In addition, the light utilization efficiency can be increased, and a highly sensitive solid-state imaging device 10 can be realized. The refractive index of the color filter layer 4 is formed using, for example, a pigment dispersion resist, and the refractive index is about 1.6 or more and 1.8 or less. The material used for the partition wall 11 is not particularly limited as long as it satisfies the refractive index. For example, if it is an inorganic material, for example, aluminum (Al), tungsten (W), copper (Cu), TEOS (tetraethoxy) A silicon oxide film typified by (silane) is preferable. If it is an organic material, the acrylic resin and polyimide resin containing a silica oxide will be mentioned, for example.
The height of the partition wall 11 may be 10 nm or more and 30000 nm or less, and particularly preferably 100 nm or more and 900 nm or less. The width of the partition wall may be 10 nm or more and 500 nm or less, and particularly preferably 100 nm or more and 300 nm or less.

<Manufacturing method>
Next, with reference to FIG. 8, a partition wall process that is a main part of the method for manufacturing the solid-state imaging device 10 according to the second embodiment will be described.
First, as shown in FIG. 8A, a semiconductor substrate 1 in which a plurality of photoelectric conversion elements 2 are arranged in a matrix in a plane is prepared, and the semiconductor substrate 1 is covered so as to cover the plurality of photoelectric conversion elements 2. A planarization layer 3 is formed on the substrate. Then, a partition wall material 12 is laminated on the planarizing layer 3. Specifically, after the partition wall material 12 is applied, the film is formed by rotation and baking, or is formed by various methods such as vapor deposition, sputtering, and CVD.

Next, as shown in FIG. 8B, after the barrier rib material 12 is formed, a resist pattern 13 is formed using a photosensitive transparent resin using a mask having a pattern along the barrier rib shape.
Next, etching is performed using the resist pattern 13 as a mask. Then, the partition 11 is formed by removing the resist using ashing or a stripping solution. Etching can be wet etching or dry etching. Dry etching is preferable because the fine line width of the partition wall 11 can be obtained with high accuracy.
Here, when the partition 11 is formed of an inorganic material, there is a problem that the adhesion between the undercoat layer formed using a photosensitive transparent resin and the partition 11 is low. Therefore, the material used for the undercoat layer 7 is selected from materials that are transparent and have excellent photosensitivity and adhesion between inorganic materials. Moreover, you may implement the process of improving adhesiveness by HMDS process (1,1,1,3,3,3-hexamethyldisilazane) and UV irradiation after the partition 11 formation.

Hereinafter, examples and comparative examples will be described.
(Example 3)
A solid-state imaging device of Example 3 was produced by the following method.
A silicon wafer having a thickness of 0.75 mm and a diameter of 20 cm was used as the semiconductor substrate. A plurality of photoelectric conversion elements made of CMOS as photoelectric conversion elements were arranged on the upper surface of the silicon wafer so as to form a Bayer array. Here, the arrangement period of the pixels of the photoelectric conversion element was 1.1 μm.

Next, a film made of a styrene-based transparent resin was formed by spin coating, and baked at 200 ° C. for 2 minutes to form a planarization layer. The thickness of the planarizing layer was 40 nm.
Next, in forming the undercoat layer on the planarization layer, the microlens under the green (G) pixel is located at a position where the focal point of the microlens under the red (R) pixel is 2200 nm from the surface of the photoelectric conversion element. The film thickness of the undercoat layer is set so that the focal point of the microlens under the blue (B) pixel corresponds to the position of 300 nm from the surface of the photoelectric conversion element. did.

In the undercoat layer forming process, first, a positive resist made of an acrylic transparent resin having alkali solubility and photosensitivity is applied by spin coating to a thickness of 1.0 μm, and heated at 90 ° C. for 2 minutes to be hardened. Went. Thereafter, the acrylic transparent resin was exposed and developed by photolithography using a gray tone mask to form an undercoat layer. By using a gray tone mask, the film thickness of the undercoat layer in each pixel region was controlled. Thereafter, baking was performed at 180 ° C. for 2 minutes in a clean oven. The thickness of the undercoat layer in Example 1 was 32 nm under the red (R) pixel, 212 nm under the green (G) pixel, and 354 nm under the blue (B) pixel.

Next, a negative pigment dispersion resist having green (G) spectral characteristics was applied onto the undercoat layer by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel arrangement. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven. The refractive index of the negative pigment dispersion resist having the green (G) spectral characteristics was 1.70.
Next, a negative pigment dispersion resist having red (R) spectral characteristics was applied by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven. The refractive index of the negative pigment dispersion resist having red (R) spectral characteristics was 1.70.

Next, a negative pigment dispersion resist having blue (B) spectral characteristics was applied by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven. The refractive index of the negative pigment dispersion resist having the blue (B) spectral characteristics was 1.70.
Next, a thermosetting acrylic resin layer having a flattening effect and containing an infrared absorber on the three color pixels of the color filter layer is applied by spin coating, and then cleaned at 200 ° C. in a clean oven. Then, a baking process was performed for 10 minutes to form a planarization layer. The film thickness was 0.5 μm.

Next, a microlens was formed on the color filter layer and the flattening layer. First, an acrylic transparent resin having alkali solubility and photosensitivity was applied by spin coating, and the film was hardened by heating at 90 ° C. for 2 minutes. Thereafter, microlenses were formed on the acrylic transparent resin by photolithography using a gray tone mask. By using the gray tone mask, the mask transmittance distribution in the pixel can be controlled, so that an arbitrary microlens shape can be formed.

Example 4
In Example 4, the focal point of the microlens under the red (R) pixel is 2400 nm from the surface of the photoelectric conversion element, and the focal point of the microlens under the green (G) pixel is 850 nm from the surface of the photoelectric conversion element. The film thickness of the undercoat layer is set so that the focal point of the microlens under the blue (B) pixel corresponds to the position of 2400 nm from the surface of the photoelectric conversion element at the position of However, a solid-state imaging device was fabricated in the same manner as in Example 1 except that the thickness was 22 nm under the red (R) pixel, 198 nm under the green (G) pixel, and 330 nm under the blue (B) pixel.

(Example 5)
In Example 5, a solid-state imaging device was formed in the same manner as in Example 1 except that the partition walls described below were formed on the planarization layer formed on the semiconductor substrate.
A silicon oxide film was formed by an evaporation method, an acrylic transparent resin having alkali solubility and photosensitivity was applied by spin coating, and the film was cured by heating at 90 ° C. for 2 minutes. Next, a protective film was formed on the acrylic transparent resin by a photolithography method. Next, dry etching was performed using a fluorocarbon gas using the protective film as a mask to form partition walls. As a gas at the time of dry etching, a mixed gas with a chlorine gas, a halogen gas, hydrogen, nitrogen, oxygen, a rare gas, or the like may be used in addition to the fluorine gas. At this time, the partition wall height was 800 nm and the inter-pixel width was 100 nm. Moreover, the refractive index of the partition was 1.45.

(Comparative Example 2)
A solid-state imaging device was produced in the same manner as in Example 3 except that the undercoat layer was not formed.
(Comparative Example 3)
A solid-state imaging device of Comparative Example 3 was produced in the same manner as in Example 5 except that the undercoat layer was not formed.
The light receiving efficiencies of the solid-state imaging devices obtained in Examples 3 to 5 and Comparative Examples 2 and 3 were measured. A value obtained by setting the light receiving efficiency of Comparative Example 2 to 100% was calculated as the light receiving sensitivity. These results are shown in Table 2.

From Table 2, in comparison with Comparative Example 2, the solid-state imaging device of Example 3 is about 5.4%, the solid-state imaging device of Example 4 is about 4.9%, and Example 3 is 10.4% light receiving sensitivity. It can be seen that both obtained good results. In addition, Example 5 was about 5.4% higher than Comparative Example 3.

(Embodiment 3)
The configuration of the solid-state imaging device 6 according to Embodiment 3 will be described with reference to FIGS. 9 and 10.
<Configuration>
As shown in FIGS. 9 and 10, the solid-state imaging device 6 </ b> A of Embodiment 3 includes a photoelectric conversion device 2, a planarization layer 3, an undercoat layer 7, and a plurality of color filters 4 </ b> R, 4 </ b> G on a semiconductor substrate 1. A color filter layer 4a made of 4B and 4IR and a microlens 5 are laminated in this order. In FIG. 10, in order to make the arrangement of the photoelectric conversion element 2 and the color filter easier to understand, other configurations in the solid-state imaging element 6A are omitted.

On the semiconductor substrate 1, photoelectric conversion elements 2 made of CMOS or CCD are formed in a matrix as light receiving elements. A silicon oxide film or a silicon nitrogen oxide film (not shown) is formed on the surface of the semiconductor substrate 1, and a planarizing layer 3 made of a transparent resin is formed on the semiconductor substrate 1. On the planarizing layer 3, an undercoat layer 7 made of a transparent resin is formed with an appropriate film thickness corresponding to each pixel. Further, a color filter layer 4a made of a transparent resin in which a coloring material such as a pigment or a dye is dispersed is formed on the undercoat layer 7. The color filter layer 4a of the third embodiment includes a red (R) filter 4R, a green (G) filter 4G, a blue (B) filter 4B, and an infrared (IR) filter 4IR. Note that the pixel array and the color of the color filter are not limited to these. The combination of colors may be a combination provided with a color filter such as yellow or transparent. On these color filter layers 4a, microlenses 5 are formed corresponding to the photoelectric conversion elements 2.

As shown in FIG. 11, when the red (R) filter 4R, the green (G) filter 4G, the blue (B) filter 4B, and the infrared (IR) filter 4IR have the same film thickness and the undercoat layer 7 is not provided, The light incident on the microlens 5 passes through each filter and is focused at different positions in the thickness direction of the photoelectric conversion element 2.
Specifically, light with a red (R) wavelength passes through the photoelectric conversion element relatively deeply to about 2000 nm. Accordingly, in the red (R) pixel region, it is desirable that the focal position of the microlens 5 is a position 8c in the photoelectric conversion element layer. FIG. 12 shows the light receiving sensitivity when the focal point of the microlens 5 is changed in a range in which the distance from the surface of the red (R) photoelectric conversion element (interface with the planarization layer) is 0 nm or more and 3500 nm or less. . From FIG. 12, it can be seen that, under the red (R) pixel, the light receiving sensitivity peaks when the focal point of the microlens 5 is in the range of 2000 nm to 2500 nm from the surface of the photoelectric conversion element.

Light having a green (G) wavelength is transmitted to a depth of about 600 nm of the photoelectric conversion element. In accordance with this, in the green (G) pixel region, it is desirable that the focal position is the position 8b in the photoelectric conversion element layer. FIG. 12 shows the light receiving sensitivity when the focal point of the microlens 5 is changed in a range where the distance from the surface of the green (G) photoelectric conversion element is 0 nm or more and 1500 nm or less. From FIG. 12, it can be seen that, under the green (G) pixel, the light receiving sensitivity reaches a peak when the focus of the microlens 5 is in the range of 600 nm to 900 nm from the surface of the photoelectric conversion element.
Blue (B) wavelength light is transmitted to a depth of about 200 nm near the surface of the photoelectric conversion element. Accordingly, in the blue (B) pixel region, it is desirable that the focal position is a position 8a in the vicinity of the surface of the photoelectric conversion element. FIG. 12 shows the light receiving sensitivity when the focal point of the microlens 5 is changed in a range where the distance from the surface of the blue (B) photoelectric conversion element is 0 nm or more and 1500 nm or less. From FIG. 12, it can be seen that, under the blue (B) pixel, the light receiving sensitivity reaches a peak when the focus of the microlens 5 is in the range of 200 nm to 500 nm from the surface of the photoelectric conversion element.

Infrared (IR) wavelength light passes through the photoelectric conversion element to a depth of about 3000 nm. Accordingly, in the infrared (IR) pixel region, it is desirable that the focal position is a position 8d in the photoelectric conversion element layer. FIG. 12 shows the light receiving sensitivity when the focal point of the microlens 5 is changed within a range where the distance from the surface of the photoelectric conversion element of infrared rays (IR) is 0 nm or more and 5000 nm or less. From FIG. 12, it can be seen that, under the infrared (IR) pixel, the light receiving sensitivity of the focus of the microlens 5 increases from 1500 nm from the surface of the photoelectric conversion element, and the light receiving sensitivity reaches a peak in the range of 3000 nm to 5000 nm.

From the above, in the solid-state imaging device 6A of Embodiment 3, the focal point of the microlens 5 is the distance from the surface of the photoelectric conversion device, and the range of 2000 nm to 2500 nm below the red (R) pixel, green (G ) The planarizing layer 3 has a range of 600 nm to 900 nm under the pixel, a range of 200 nm to 500 nm under the blue (B) pixel, and a range of 1500 nm to 5000 nm under the infrared (IR) pixel. The thickness of the undercoat layer 7 provided between the color filter layer 4a and the color filter layer 4a is set for each pixel.

Here, the vertexes 5a of the microlenses 5 on the color filter layer 4A are substantially the same height. As a result, the distribution of incident light to red (R), green (G), blue (B), and infrared (IR) pixels can be easily controlled, and the sensitivity of the solid-state imaging device is stabilized by the depth of focus of the microlens 5. Can be changed.
As shown in FIG. 10, the height of the microlens 5 is set to red (R), green (G), blue (B), and infrared (IR) so that the vertexes 5a of the microlens 5 are approximately the same height. ) It may be changed for each pixel.

<Manufacturing method>
Next, a method for manufacturing the solid-state imaging element 6A of Embodiment 3 will be described with reference to FIG. First, a semiconductor substrate 1 in which a plurality of photoelectric conversion elements 2 are arranged in a matrix in a plane is prepared, and a planarization layer 3 is formed on the semiconductor substrate 1 so as to cover the plurality of photoelectric conversion elements 2. After this planarization layer stacking step, an undercoat layer corresponding to each pixel is formed.
In the undercoat layer forming step, first, as shown in FIG. 13A, a liquid (photoresist) containing a transparent photosensitive transparent resin is applied on the planarizing layer 3 with a predetermined thickness, and the liquid layer 70 is formed. Form. Next, as shown in FIGS. 13B and 13C, the liquid layer 70 is subjected to exposure, development, and baking processes based on the photolithography method using the gray-tone mask 9, thereby subtracting. Layer 7 is formed.

By changing the transmittance of the gray tone mask 9 at each position of the red (R) filter, green (G) filter, blue (B) filter, and infrared (IR) filter in this undercoat layer forming step, The in-plane thickness of the pulling layer 7 is controlled so that the focal point of the microlens 5 under each pixel is in the above-described range.
In this step, it is easy to control the thickness within the surface of the undercoat layer 7 by using the gray tone mask 9 that can arbitrarily change the mask transmittance gradation. The gradation of the mask transmittance gradation is achieved by a partial difference in density per unit area of small diameter dots that are not resolved by light used for exposure.

After the undercoat layer is formed, a plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements 2 on the undercoat layer, that is, a red (R) filter 4R, a green (G) filter 4G, and a blue color ( B) A color filter layer 4a composed of a filter 4B and an infrared (IR) filter 4IR is formed. After this color filter layer forming step, a microlens forming step for forming a plurality of microlenses 5 is performed. These steps can be performed by applying a conventionally known photolithography method, etching method, printing method, or the like. In particular, it is preferable to use the gray tone mask 9 that can arbitrarily change the mask transmittance gradation because the microlens vertex 5a can be easily controlled.

Hereinafter, examples and comparative examples will be described.
(Example 6)
A solid-state imaging device of Example 6 was produced by the following method.
A silicon wafer having a thickness of 0.75 mm and a diameter of 20 cm was used as the semiconductor substrate. A plurality of photoelectric conversion elements made of CMOS were arranged as photoelectric conversion elements on the upper surface of the silicon wafer. Here, the arrangement period of the pixels of the photoelectric conversion element was 1.1 μm.
Next, a film made of a styrene-based transparent resin was formed by spin coating, and baked at 200 ° C. for 2 minutes to form a planarization layer. The thickness of the planarizing layer was 40 nm.

Next, in forming the undercoat layer on the planarization layer, the microlens under the green (G) pixel is located at a position where the focal point of the microlens under the red (R) pixel is 2200 nm from the surface of the photoelectric conversion element. The focal point of the microlens under the blue (B) pixel is 300 nm from the surface of the photoelectric conversion element, and the focal point of the microlens under the infrared (IR) pixel is at the position of 700 nm from the surface of the photoelectric conversion element. The film thickness of the undercoat layer was set so as to correspond to a position of 2000 nm from the surface of the photoelectric conversion element.

In the undercoat layer forming process, first, a positive resist made of an acrylic transparent resin having alkali solubility and photosensitivity is applied by spin coating to a thickness of 1.0 μm, and heated at 90 ° C. for 2 minutes to be hardened. Went. Thereafter, the acrylic transparent resin was exposed and developed by photolithography using a gray tone mask to form an undercoat layer. By using a gray tone mask, the film thickness of the undercoat layer in each pixel region was controlled. Thereafter, baking was performed at 180 ° C. for 2 minutes in a clean oven. The thickness of the undercoat layer in Example 1 is 32 nm under the red (R) pixel, 212 nm under the green (G) pixel, 354 nm under the blue (B) pixel, and 340 nm under the infrared (IR) pixel. there were.

Next, a negative pigment dispersion resist having green (G) spectral characteristics was applied onto the undercoat layer by spin coating. The green resist is C.I. I. Pigment yellow 139, C.I. I. Pigment green 36, C.I. I. Pigment Blue 15: 6 was used, and a color resist having a constitution in which an organic solvent such as cyclohexanone and PGMEA, a polymer varnish, a monomer, and an initiator were added was used. After applying the green resist, alignment with the pixels was performed, and then exposure and development processing were performed by a photolithography method to form a predetermined pattern that matched the pixel arrangement. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven. The negative pigment dispersion resist having the green (G) spectral characteristics had a refractive index of 1.70 and a film thickness of 700 nm.

Next, a negative pigment dispersion resist having red (R) spectral characteristics was applied by spin coating. The color material of the red resist is C.I. I. Pigment red 117, C.I. I. Pigment red 48: 1, C.I. I. Pigment Yellow 139. The composition other than the color material was the same as that of the green resist. After applying the red resist, alignment with the pixel was performed, and then exposure and development processing were performed by a photolithography method, thereby forming a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven. The negative pigment dispersion resist having red (R) spectral characteristics had a refractive index of 1.70 and a film thickness of 700 nm.

Next, a negative pigment dispersion resist having a blue (B) spectral characteristic was applied by spin coating. The blue resist is C.I. I. Pigment blue 15: 6, C.I. I. A pigment violet 23 was used, and a color resist having a constitution in which an organic solvent such as cyclohexanone and PGMA, a polymer varnish, a monomer, and an initiator were added was used. After applying the blue resist, alignment with the pixel was performed, and then exposure and development processing were performed by a photolithography method to form a predetermined pattern in accordance with the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven. The negative pigment dispersion resist having blue (B) spectral characteristics had a refractive index of 1.70 and a film thickness of 600 nm.

Next, a negative pigment dispersion resist having infrared (IR) spectral characteristics was applied by spin coating. After alignment with the pixels, exposure and development processing were performed by a photolithography method to form a predetermined pattern corresponding to the pixel array. Thereafter, baking was performed at 200 ° C. for 10 minutes in a clean oven. The negative pigment dispersion resist having infrared (IR) spectral characteristics had a refractive index of 1.70 and a film thickness of 800 nm.
Next, a thermosetting type acrylic resin layer having a flattening effect is applied onto the pixels of the color filter layer by spin coating, and a baking process is performed at 200 ° C. for 10 minutes in a clean oven, so that the flattening layer Formed. The film thickness was 0.5 μm.

Next, a microlens was formed on the planarizing layer. First, an acrylic transparent resin having alkali solubility and photosensitivity was applied by spin coating, and the film was hardened by heating at 90 ° C. for 2 minutes. Thereafter, microlenses were formed on the acrylic transparent resin by photolithography using a gray tone mask. By using the gray tone mask, the mask transmittance distribution in the pixel can be controlled, so that an arbitrary microlens shape can be formed.

(Example 7)
In Example 7, the focal point of the microlens under the red (R) pixel is 2400 nm from the surface of the photoelectric conversion element, and the focal point of the microlens under the green (G) pixel is 850 nm from the surface of the photoelectric conversion element. The focal point of the micro lens under the blue (B) pixel is 240 nm from the surface of the photoelectric conversion element, and the focal point of the micro lens under the infrared (IR) pixel is 2000 nm from the surface of the photoelectric conversion element. The thickness of the undercoat layer is set so as to correspond to the position, and the thickness of the formed undercoat layer is 22 nm under the red (R) pixel, 198 nm under the green (G) pixel, and blue (B) pixel. A solid-state imaging device was produced in the same manner as in Example 1 except that the thickness was 330 nm below and 340 nm below the infrared (IR) pixel.

(Comparative Example 4)
A solid-state imaging device was produced in the same manner as in Example 6 except that the undercoat layer was not formed.
The light receiving efficiency of the solid-state imaging devices obtained in Example 6, Example 7, and Comparative Example 4 was measured. A value obtained by setting the light receiving efficiency of Comparative Example 4 to 100% was calculated as the light receiving sensitivity. These results are shown in Table 3.

From Table 3, in comparison with Comparative Example 4, the solid-state imaging device of Example 6 has a high light receiving sensitivity of about 5.4%, and the solid-state imaging device of Example 7 has a high light receiving sensitivity of about 4.9%. You can see that it was obtained.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. In the image sensor as the solid-state imaging device according to the fourth embodiment, microlenses having different heights are set as parameters for changing the condensing position.
As shown in FIG. 14, an image sensor that is a solid-state imaging device according to the fourth embodiment includes a large number of photoelectric conversion elements 103, a planarization layer 3a, a color separation filter (color filter) 102, and a microlens on a semiconductor substrate 104a. 101 are stacked in this order, and each pixel of green, blue, and red is formed for each photoelectric conversion element as a unit. In the example of FIG. 14, the color separation filter 102, the flattening layer 3 a below the photoelectric conversion element 103, and the photoelectric conversion element 103 are illustrated, but in this specification, the semiconductor substrate 104 a, the photoelectric conversion element 103, the flattening layer 3 a, and the color separation filter 102. The microlens 101 and so on are referred to as an image sensor. The semiconductor substrate 104a is obtained by, for example, dividing a silicon wafer made of single crystal silicon into individual chip formation regions (image sensors) in a manufacturing method described later.

As shown in FIG. 15, in the fourth embodiment, a G (green) filter 102b is provided for every other pixel, and R (red) filters 102a and B (every other row are provided between the G filters 102b. Blue) It is a so-called Bayer array provided with a filter 102c.
An electrical signal of image information obtained by the image sensor is guided to the back surface of the semiconductor substrate 104a by a conductive material that fills the inside of the through hole or covers the inner wall via an electrode (not shown), and is patterned insulation. The layer and the conductive layer are connected to the external circuit from the external connection pad 105 via the connection bump 106 by the BGA method.

In addition, an electroless plating layer for preventing flare and having a light shielding property may be provided on the side wall of the lens module. The material is a single plating layer of a metal selected from nickel, chromium, cobalt, iron, copper, gold, etc., and an alloy selected from a combination of nickel-iron, cobalt-iron, copper-iron, etc. An electroplating layer is mentioned. In addition, a metal such as copper can be electrolessly plated, and then the surface thereof can be chemically or oxidized to form a metal compound to form a metal light-shielding layer having a low light reflectance on the surface.
Here, in the image sensor of Embodiment 4, when the height of the microlens 101 on the green pixel is 100%, the height of the microlens 101 on the blue pixel is in the range of 105% to 150%. Further, the height of the microlens 101 on the red pixel is set in the range of 95% to 70%. According to the image sensor of the fourth embodiment, it is possible to collect light at the optimum depth of the image sensor by adjusting the height of the microlens for each pixel. Thereby, the light receiving sensitivity is improved.

FIG. 16 shows an example of the light reception sensitivity curve of each pixel of red, green, and blue in a general image sensor, and FIG. 18 shows blue, green, The transmission and reception image of red incident light is shown.
As shown in FIG. 18, red transmits to a relatively deep layer 103 c of the image sensor due to a difference in light transmittance and the like. Accordingly, in the image sensor according to the fourth embodiment, as shown in FIG. 19, the height of the microlens 101c of the red pixel is relatively set with reference to the height of the microlens 101b on the green pixel. The relative height is lowered by 101d, so that the light condensing position is the inside 103c of the image sensor layer.
Here, the light receiving sensitivity when the height of the green and blue microlenses is fixed to 580 nm and the height of the red microlens is changed from 551 nm to 348 nm is shown in Examples 7 to 11 in Table 4. Moreover, the graph of the result is shown in FIG.

As shown in Table 4 and FIG. 26A, the height of the microlens 101b on the green pixel is 100%, and the height of the microlens 101c on the red pixel is 100% (580 nm) to 95% ( 551 nm), no influence on the light receiving sensitivity was observed (Example 7 in Table 4).
On the other hand, as shown in FIG. 26A, when the height of the microlens 101c on the red pixel is 70% (406 nm) or less, it was confirmed that the light receiving sensitivity of the red pixel is reduced (Example 11 in Table 4). ). Therefore, it can be seen that the height of the microlens 101c on the red pixel is preferably in the range of 70% to 95% when the height of the microlens on the green pixel is 100% (FIG. 26A).

Further, as shown in FIG. 18, blue is received in the vicinity of the image sensor surface 103a due to a difference in light transmittance and the like. Accordingly, in the image sensor according to the fourth embodiment, as shown in FIG. 20, the height of the microlens 101b of the blue pixel is relatively set based on the height of the microlens 101b on the green pixel. The light collecting position is set to the image sensor surface vicinity 103a by increasing the relative height 101e.
Here, the light receiving sensitivity when the height of the green and red microlenses is fixed to 580 nm and the height of the blue microlens is changed from 609 nm to 928 nm is shown in Examples 2 to 6 in Table 4. Moreover, the graph of the result is shown in FIG.

As shown in Table 4 and FIG. 26B, the height of the microlens 101b on the green pixel is 100%, and the height of the microlens 101a on the blue pixel is 100% (580 nm) to 105% ( 609 nm), no influence on the light receiving sensitivity was observed (Example 1 and Example 2 in Table 4).
On the other hand, as shown in FIG. 26B, it was confirmed that when the height of the microlens 101a on the blue pixel is 150% (928 nm) or more, the light receiving sensitivity of the green pixel around the blue pixel is lowered ( Example 6 in Table 4). For this reason, it can be seen that the height of the microlens 101a on the blue pixel is desirably in the range of 105% to 150% (FIG. 26B).

Next, a method for manufacturing the microlens 101 formed on the photoelectric conversion element 103 described above will be described in detail based on examples.
(Example 8)
Example 8 will be described with reference to FIGS. 17, 21, and 22.
In Example 8, the photosensitive microlens material 111 (see FIG. 21B) composing the microlens 101 is a photosensitive transparent resin, and is an example using a positive photosensitive resin. In this embodiment, different microlens heights for each pixel of the microlens 101 are controlled by the exposure method. Therefore, a special exposure mask called gray tone mask 150 shown in FIG. 17 is used.

A gray tone mask 150 shown in FIG. 17 is a mask in which light transmittance is increased with respect to a microlens-shaped lens bottom to be created, and a light shielding film is provided with a gradation (gradation) of light and shade. This gradation of gradation is achieved by the difference in the number (rough density) of small-diameter dots per unit area that is not resolved by the light used for exposure. In the gray tone mask 150, the transmitted light distribution of the mask is varied depending on each pixel of green, blue, and red.
In the example of FIG. 17, reference numeral 150 a indicates the gray tone mask transmitted light distribution of the microlens on the red pixel, reference numeral 150 b indicates the graytone mask transmitted light distribution of the microlens on the green pixel, and reference numeral 150 c indicates the blue pixel. The distribution of light transmitted through the gray-tone mask of the upper microlens is shown. In the drawing, a bright part has little transmitted light and a dark part has much transmitted light.

In Example 8, for example, a photoelectric conversion element 103 (see FIG. 14), a light-shielding film, and a passivation film are formed on a silicon wafer 104 made of single crystal silicon having a thickness of 0.75 mm and a diameter of 20 cm as a semiconductor substrate, and the uppermost layer is formed. Then, the planarization layer 3a (see FIG. 14) was formed by spin coating using a thermosetting acrylic resin coating solution. Next, the color separation filter 102 is formed on the planarizing layer 3a by three photolithography techniques in three colors of green, blue, and red (see FIG. 21A). The photoelectric conversion element and the planarization layer are not shown.)

Green resist is a C.I. I. Pigment yellow 139, C.I. I. Pigment green 36, C.I. I. Pigment Blue 15: 6 was used, and a color resist having a constitution in which an organic solvent such as cyclohexanone and PGMEA, a polymer varnish, a monomer, and an initiator were added was used.
Blue resist is C.I. I. Pigment blue 15: 6, C.I. I. A pigment violet 23 was used, and a color resist having a constitution in which an organic solvent such as cyclohexanone and PGMA, a polymer varnish, a monomer, and an initiator were further added was used.

The color material of the red resist is C.I. I. Pigment red 117, C.I. I. Pigment red 48: 1, C.I. I. Pigment Yellow 139. The composition other than the color material was the same as that of the green resist.
The arrangement of the colored pixels is a so-called Bayer arrangement in which a G (green) filter is provided every other pixel, and an R (red) filter and a B (blue) filter are provided every other row between the G filters.
Next, as shown in FIG. 21B, styrene having alkali-soluble, photosensitive, and thermal reflow properties with a thickness of 1 μm is formed on the entire surface of the silicon wafer 104 including the color separation filter (each color filter) 102. Resin was applied to form a photosensitive microlens material 111. Thereafter, as shown in FIG. 21C, the photosensitive microlens material 111 is patterned by a photolithography process using ultraviolet i rays using a gray-tone mask 150, and then heat-treated at 250 ° C. As shown in (d), a microlens 101 was formed.

The green pixel of the microlens 101 has a smooth semi-parabolic shape with a height of about 0.62 μm, the red pixel has a smooth semi-parabolic shape with a height of 0.53 μm, and the blue pixel has a height of 0.74 μm. It was. In this way, an image sensor multi-faced on the silicon wafer 104 was completed (FIG. 21D).
Next, a photoresist is applied to the back surface of the silicon wafer 104, an opening is formed at a site where a through hole is to be formed by a regular photolithography method, and then reactive ion etching is performed using the photoresist film as a mask. The silicon wafer 104 was etched to a predetermined depth to form through holes. Next, in order to insulate the silicon wafer 104 from a wiring layer to be formed later, a SiO ₂ insulating film was formed on the entire inner wall, bottom, and back surface of the through hole by a CVD method.

Here, the insulating film was formed such that the thickness of the insulating film was thinner on the bottom of the through hole (which is a pad made of a highly conductive metal such as aluminum) than on the back surface of the silicon wafer 104. Then, reactive ion etching was performed again to remove the insulating film at the bottom of the through hole. Subsequently, a conductive film was formed by sputtering, and a through hole was buried and a wiring layer on the back surface of the wafer was formed.
Next, a portion of the wiring layer to be connected to the outside was exposed by a regular photolithography method. A solder paste was applied to the exposed portion by screen printing, and a solder ball was mounted. When reflow processing was performed to remove residual flux, an image sensor substrate having external connection pads 105 and connection bumps 106 was obtained (FIG. 22B).

Finally, a dicing apparatus using a 450 mesh resin blade was used to cut a groove from the surface with the middle part of the image sensor multi-faceted in a matrix as a cutting line (FIG. 22 (c)). Thereafter, as shown in FIG. 22 (d), the product was separated into individual image sensors to obtain a finished product in the state shown in FIG. 22 (e). That is, a plurality of image sensors were obtained in which a large number of photoelectric conversion elements 103, color separation filters 102, and microlenses 101 were stacked in this order on a semiconductor substrate 104a.

As a result of measuring the light receiving sensitivity of each pixel, the light receiving sensitivity of red was 64.2%, the light receiving sensitivity of green was 60.0%, and the light receiving sensitivity of blue was 43.9% (Example 3 in Table 4). Improvement was confirmed with respect to the standard example (Example 1 in Table 4) having the same pixel height. If necessary, a process such as bleaching may be performed to control the shape and light transmittance of the microlens.
The AFM observation shape of the microlens obtained in Example 8 is shown in FIG. In the conventional microlens manufacturing method, the microlens for each pixel has the same shape, but in Example 8, microlenses having different heights are formed at the same pitch for each pixel.

Example 9
Example 9 will be described with reference to FIGS. 23 and 24. FIG.
In Example 9, a photoelectric conversion element 103 (see FIG. 14), a light-shielding film, and a passivation film are formed on a silicon wafer 104 having a thickness of 0.75 mm and a diameter of 20 cm, and a thermosetting acrylic resin coating liquid is formed on the uppermost layer. Was used to form a planarization layer by spin coating. Next, the color separation filter 102 was formed on the planarizing layer 3a (see FIG. 14) by three photolithography techniques in three colors of green, blue, and red (FIG. 23A). (Refer to photoelectric conversion element and planarization layer not shown.)

Green resist is a C.I. I. Pigment yellow 139, C.I. I. Pigment green 36, C.I. I. Pigment Blue 15: 6 was used, and a color resist having a constitution in which an organic solvent such as cyclohexanone and PGMEA, a polymer varnish, a monomer, and an initiator were added was used.
Blue resist is C.I. I. Pigment blue 15: 6, C.I. I. A pigment violet 23 was used, and a color resist having a constitution in which an organic solvent such as cyclohexanone and PGMA, a polymer varnish, a monomer, and an initiator were further added was used.

The color material of the red resist is C.I. I. Pigment red 117, C.I. I. Pigment red 48: 1, C.I. I. Pigment Yellow 139. The composition other than the color material was the same as that of the green resist.
The arrangement of the colored pixels is a so-called Bayer arrangement in which a G (green) filter is provided every other pixel, and an R (red) filter and a B (blue) filter are provided every other row between the G filters.

Next, as shown in FIG. 23B, an acrylic resin coating liquid in which a benzene ring is introduced into the resin skeleton is applied to the entire surface of the silicon wafer 104 including the color separation filter (each color filter) 102. A transparent resin layer 112 having a thickness of 1 μm was formed, and the film was hardened by heating at 180 ° C. for 3 minutes.
Further, a photosensitive sacrificial layer 113 was formed by applying a styrene resin having alkali solubility, photosensitivity, and heat reflow (FIG. 23C). Thereafter, as shown in FIG. 23C, the photosensitive sacrificial layer 113 was patterned by a photolithography process using a KrF laser using the gray tone mask 150. The gray tone mask 150 is a mask in which light transmittance is increased with respect to a microlens-shaped lens bottom to be created, and a shading film is provided with gradation (gradation) of light and shade. This gradation of gradation is achieved by the difference in the number (rough density) of small-diameter dots per unit area that is not resolved by the light used for exposure.

Thereafter, heat treatment was performed at 250 ° C. to form the lens matrix 113a with a substantially appropriate flow amount of 0.1 μm on one side (FIG. 23 (d)). The lens matrix 113a has a smooth semi-parabolic shape with a thickness of about 0.7 μm, and the concave lens curvature diameter between adjacent lens matrices 113a is 0.2 μm.
Next, as shown in FIG. 23D, dry etching is performed using a mixed gas of CF ₄ and C ₃ F ₈ which is a fluorocarbon gas, and the pattern of the lens matrix 113a is made of a transparent resin made of acrylic resin. Transferring to the layer 112, a microlens 112a was formed as shown in FIG. The dry etching time was 5 minutes. The green pixel of the microlens 112a has a smooth semi-parabolic shape with a height of about 0.58 μm, the red pixel has a smooth semi-parabolic shape with a height of 0.49 μm, and the blue pixel has a height of 0.70 μm. It was. In this way, an image sensor with multiple faces on the silicon wafer 104 was completed (FIG. 24A).

Next, a photoresist was applied to the back surface of the silicon wafer 104, and an opening was formed at a site where a through hole was to be formed by a regular photolithography method. Next, reactive ion etching was performed using the photoresist film as a mask, and the silicon wafer 104 was etched to a predetermined depth to form through holes. Next, in order to insulate the silicon wafer 4 from a wiring layer to be formed later, a SiO ₂ insulating film was formed on the entire inner wall, bottom, and back surface of the through hole by a CVD method.
Here, the insulating film was formed such that the thickness of the insulating film was thinner on the bottom of the through hole (which is a pad made of a highly conductive metal such as aluminum) than on the back surface of the silicon wafer 104. Then, reactive ion etching was performed again to remove the insulating film at the bottom of the through hole. Subsequently, a conductive film was formed by sputtering, and a through hole was buried and a wiring layer on the back surface of the wafer was formed.

Next, a portion of the wiring layer to be connected to the outside was exposed by a regular photolithography method. A solder paste was applied to the exposed portion by screen printing, and a solder ball was mounted. When reflow treatment was performed to remove residual flux, an image sensor substrate having external connection pads 105 and connection bumps 106 was obtained (FIG. 24B).
Finally, by using a dicing apparatus using a 450 mesh resin blade, cutting grooves were formed from the surface with the middle part of the image sensor multi-faceted in a matrix as cutting lines (FIG. 24C). After that, as shown in FIG. 4D, the image sensor was separated into individual image sensors to obtain a finished product in a state shown in FIG. That is, a plurality of image sensors were obtained in which a large number of photoelectric conversion elements 103, color separation filters 102, and microlenses 112a were stacked in this order on a semiconductor substrate 104a.

As a result of measuring the light receiving sensitivity of each pixel, the light receiving sensitivity of red was 65.1%, the light receiving sensitivity of green was 55.9%, and the light receiving sensitivity of blue was 43.8% (Example 4 in Table 4). Improvement was confirmed with respect to the standard example (Example 1 in Table 4) having the same pixel height. In addition, if necessary, steps such as heat flow and bleaching can be performed to control the shape and light transmittance of the microlens.
Further, in the photolithography method using the gray tone mask 150 of this embodiment, when a KrF laser is used, the curved surface shape of the microlens can be controlled from a curvature diameter of 120 nm to 248 nm by the wavelength limit resolution of the KrF laser. It becomes.

As described above, according to the image sensor of the fourth embodiment, light can be condensed at an optimal depth of the image sensor by adjusting the height of the microlens for each pixel. Thereby, the light receiving sensitivity is improved.
Further, according to the image sensor manufacturing method of Embodiment 4, microlens shapes having different heights for each pixel can be easily and collectively formed by a photolithography process using a gray tone mask. Therefore, the manufacturing cost can be reduced compared to the conventional multiple etching methods and multiple resist patterning methods.

Further, in the method of manufacturing the image sensor according to the fourth embodiment, by using ultraviolet i rays for photolithography, the curved surface shape of the microlens can be controlled from a curvature diameter of 180 nm to 365 nm, and a pixel size of about 1100 nm. This is effective in improving the light collection efficiency of the micro lens. Further, by using a KrF laser, the curved surface shape of the microlens can be controlled from a curvature diameter of 120 nm to 248 nm, which is effective in improving the light collection efficiency of the microlens having a pixel size of 1000 nm or less.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described.
In the fifth embodiment, the manufacturing method of the microlens 101 having different heights will be described focusing on the differences from the manufacturing method in the fourth embodiment described above, and the same reference numerals are given to the same configurations as the microlens 101. Therefore, the description is omitted.
In the fifth embodiment, two types of masks are used to form the microlenses 101 having different heights, and the microlenses 101 are manufactured through two steps. Specifically, a micro lens for a green pixel is formed using a first gray tone mask, and a micro lens for a blue pixel and a red pixel is formed using a second gray tone mask. is there. With this manufacturing method, the resolution at the boundary portion between adjacent microlenses can be improved. As a result, the shape at the boundary between adjacent microlenses can be made closer to the design shape, and deterioration of the light collection characteristics of incident light can be suppressed.

Details of the fifth embodiment will be described below.
In the fifth embodiment, as shown in FIG. 27, a first gray tone mask 120 and a second gray tone mask 130 are used. In the first gray-tone mask 120, as shown by symbol A in FIG. 27, the density gradation pattern 121 corresponding to the green pixel is in a checkered pattern (pattern in which grid-like eyes are arranged in different colors: Checkered Pattern). The other part is a photomask formed of a transmission surface on which no pattern is formed.
In the second gray-tone mask 130, as shown by a symbol B in FIG. 27, a density gradation pattern 131 corresponding to a blue pixel and a density gradation pattern 132 corresponding to a red pixel are formed in a checkered pattern. The other part is a photomask composed of a transmission surface on which no pattern is formed.

In the first gray tone mask 120 and the second gray tone mask 130, a light-shielding portion pattern made of a light-shielding film such as metal chrome is light-transmitted on a substrate such as quartz or glass having good transparency to exposure light. It consists of the structure formed distinguishing from the part. The density gradation patterns 121, 131, and 132 are formed by gradually changing the film thickness of a light-shielding metal film or the like to provide a density gradient in the region, or by dot (halftone dot) arrangement or line-and-space (line / space) The pattern is formed by a gray-tone type method or the like in which the fine pattern arrangement of the light-shielding film is changed, such as a pattern in which voids are repeated, and the average light-shielding density of each pattern region is inclined. That is, the density gradation patterns 121, 131, and 132 corresponding to the respective colors shown in FIG. 27 correspond to 150b, 150c, and 150a in FIG.

FIG. 28 is a diagram ((1) to (5)) for explaining the manufacturing method of the microlens 1 performed after the pattern formation of the color separation filter (R filter 102a, G filter 102b, B filter 102c). 28 corresponds to the YY cross section in FIG. 15, and each figure shown in B in FIG. 28 corresponds to the XX cross section in FIG. .
First, a microlens material which is a positive photoresist is applied on the color separation filter (R filter 102a, G filter 102b, B filter 102c) 102 shown in FIG. As a result, a first photoresist layer 140 is formed on the color separation filter 102 as shown in FIG. Thereafter, using a stepper, exposure is performed using the first gray-tone mask 120 as a photomask. After exposure, development with a developing solution is performed, and heat curing is performed, thereby forming a green pixel microlens 101b on the green pixel G filter 102b as shown in FIG. 28 (3) (first forming step). ).

Next, a microlens material is applied on the color separation filter 102 and the microlens 101b of the green pixel, and heat treatment is performed. As a result, as shown in FIG. 28 (4), a second photoresist layer 141 is formed on the color separation filter 102 and the microlens 101b of the green pixel. Thereafter, using a stepper, exposure is performed using the second gray-tone mask 130 as a photomask.
After the exposure, development with a developer is performed, and heat curing is performed, so that the blue pixel microlens 101a and the red pixel R filter 102a are formed on the blue pixel B filter 102c as shown in FIG. Red pixel microlenses 101c are respectively formed (second forming step).

Here, when a positive photoresist material is used, the greater the amount of light that enters the photoresist layers 140 and 141 during exposure, the deeper the photosensitivity, the thinner the remaining film after development. For this reason, the remaining film becomes thinner as the light transmittance in the photomask increases. Therefore, by using the gray tone masks 120 and 130 having the density gradation patterns 121, 131, and 132 having the above-described transmittance distribution in the photolithography process, the height of the micro lens 101a of the blue pixel is reduced to the micro pixel of the green pixel. The height of the microlens 101c of the red pixel can be made lower than the height of the microlens 101b of the green pixel.

(Example 10)
Next, Example 10 corresponding to Embodiment 5 will be described.
In Example 10, a photoelectric conversion element 103, a light shielding film, and a passivation film are formed on a silicon wafer 104 made of silicon material and having a thickness of 0.75 mm, and spin coating is performed using a thermosetting acrylic resin coating liquid as the uppermost layer. A planarizing layer was formed by coating.
Next, a green pixel G filter 102b, a blue pixel B filter 102c, and a red pixel R filter 102a were respectively formed on the planarizing layer by photolithography. Through these steps, the structure below the microlens 101 in FIG. 14 was fabricated (the light-shielding film and the passivation film are not shown).

Photoresists were formed using the same materials as in Example 8 for the green pixel G filter 102b, the blue pixel B filter 102c, and the red pixel R filter 102a. Further, the arrangement of the colored pixels is a so-called Bayer arrangement as in the example shown in FIG.
Next, a heat treatment is performed on the photosensitive microlens material 111 formed by applying a styrene resin having alkali solubility, photosensitivity, and heat reflow on the color separation filter 102, and the first photoresist layer 140 is processed. Formed. Here, the film thickness of the first photoresist layer 140 was about 0.80 μm.

Thereafter, patterning was performed by a photolithography process using ultraviolet i rays using the first gray-tone mask 120. A green pixel microlens 101b was formed by heat treatment at 250 ° C. In the first gray tone mask 120, the density gradation pattern 121 corresponding to the green pixel uses a gray tone type configuration in which a plurality of fine light shielding film portions are arranged in a halftone dot pattern.
Next, the same photosensitive microlens material 111 as that of the first photoresist layer 140 was applied onto the color separation filter 102, and heat treatment was performed to form the second photoresist layer 141. The film thickness of the second photoresist layer 141 was about 0.80 μm.

Thereafter, patterning was performed by a photolithography process using ultraviolet i rays using the second gray-tone mask 130. Then, a blue pixel microlens 101a and a red pixel microlens 101c were formed by heat treatment at 250 ° C. In the second gray tone mask 130, the density gradation pattern 131 corresponding to the blue pixel and the density gradation pattern 132 corresponding to the red pixel are gray in which a plurality of fine light-shielding film portions are arranged in a halftone dot pattern. A tone type configuration is used.

The micro pixel 101b of the green pixel has a smooth semi-parabolic shape with a height of 0.60 μm, the height of the micro lens 101a of the blue pixel is 0.69 μm, and the height of the micro lens 101c of the red pixel is 0.52 μm. It was a smooth semi-parabolic shape. In this way, an image sensor with multiple surfaces was formed on the silicon wafer 104.
As a result of measuring the light receiving sensitivity of each pixel, the light receiving sensitivity of the red pixel is 65.5%, the light receiving sensitivity of the green pixel is 56.2%, and the light receiving sensitivity of the blue pixel is 44.6%. Improvement was confirmed with respect to the standard example (Example 1 in Table 4). If necessary, a process such as bleaching may be performed to control the shape and light transmittance of the microlens.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described. The image sensor according to the sixth embodiment is an example in which the focal depth of the microlens for each pixel is set as a parameter for changing the condensing position. Since the image sensor according to the sixth embodiment can be manufactured by the same method as the manufacturing method according to the fourth embodiment described above (Examples 8 to 9), the method for manufacturing the image sensor according to the sixth embodiment is described below. Description is omitted.
As shown in FIG. 29, in the image sensor of the sixth embodiment, a large number of photoelectric conversion elements 203, a planarization layer 3a, a color separation filter 202, and a microlens 201 are stacked in this order on a semiconductor substrate 204a. Each pixel of blue and red is formed for each photoelectric conversion element as a unit.

In the example of FIG. 29, the color separation filter 202 and the photoelectric conversion element 203 under the color separation filter 202 are shown. However, in this specification, the silicon wafer 204, the photoelectric conversion element 203, the planarization layer 3a, the color separation filter 202, and the microlens 201 are included. Is called an image sensor.
As shown in FIG. 30, in the sixth embodiment, a G (green) filter 202b is provided for every other pixel, and R (red) filters 202a and B (every other row) are provided between the G filters 202b. Blue) It is a so-called Bayer array provided with a filter 202c. The semiconductor substrate 204a is obtained by dividing a silicon wafer made of, for example, single crystal silicon into individual chip formation regions (image sensors) in the manufacture thereof, as in the fourth embodiment.

The electrical signal of the image information obtained by the image sensor is guided to the back surface of the semiconductor substrate 204a by a conductive material filling the through hole or covering the inner wall via an electrode (not shown), and patterned insulation. The layer and the conductive layer are connected to an external circuit from the external connection pad 205 via the connection bump 206 by the BGA method.
In addition, an electroless plating layer for preventing flare and having a light shielding property may be provided on the side wall of the lens module. The material is a single plating layer of a metal selected from nickel, chromium, cobalt, iron, copper, gold, etc., and an alloy selected from a combination of nickel-iron, cobalt-iron, copper-iron, etc. An electroplating layer is mentioned. In addition, a metal such as copper can be electrolessly plated, and then the surface thereof can be chemically or oxidized to form a metal compound to form a metal light-shielding layer having a low light reflectance on the surface.

Here, FIG. 31 shows an example of the light reception sensitivity curve of each pixel of red, green, and blue in a general image sensor. FIG. 32 shows the transmission and reception image of blue, green, and red incident light to the inner layer of the image sensor according to the sixth embodiment.
As shown in FIG. 32, the blue wavelength is received at a depth of about 200 nm in the vicinity 203c of the image sensor surface. For this reason, it is desirable that the condensing position of the microlens 201c be the image sensor surface vicinity 203c in accordance with this. Table 5 shows the light receiving sensitivity when the focal depth of the micro lens 201c of the blue pixel is changed from 0 nm to 1500 nm. In Table 5, the microlens height of the microlens produced by the image sensor manufacturing method of Embodiment 6 is compared with the light receiving sensitivity. The graph of the result is shown in Blue (lower row) of FIG.

As is clear from the graph, it was found that the focal depth of the blue pixel microlens 201c had a peak between 200 nm and 500 nm. For this reason, the focal depth of the micro lens 201c of the blue pixel is an inner position of 200 nm or more and 500 nm or less from the surface of the photoelectric conversion element 203 on the micro lens 201 side toward the film thickness direction of the photoelectric conversion element 203, that is, photoelectric conversion. A position of 200 nm or more and 500 nm or less from the boundary surface between the element 203 and the planarization layer 3a toward the photoelectric conversion element 203 side is desirable.

On the other hand, the green wavelength is transmitted to a depth of about 600 nm in the inner layer 203b of the image sensor. Therefore, it is desirable that the condensing position of the microlens 201b be the image sensor layer interior 203b in accordance with this. The light receiving sensitivity when the green microlens height is changed from 0 nm to 1500 nm is also shown in Table 5. Moreover, the graph of the result is shown in Green (middle) of FIG.
As is apparent from the graph, it was found that the focal depth of the microlens 201b of the green pixel has a peak between 600 nm and 900 nm. For this reason, the focal depth of the microlens 201b of the green pixel is 600 nm or more and 900 nm or less from the surface of the photoelectric conversion element 203 on the microlens 201 side in the photoelectric conversion element 203 toward the film thickness direction of the photoelectric conversion element 203. The position, that is, the position of 600 nm or more and 900 nm or less from the boundary surface between the photoelectric conversion element 203 and the planarization layer 3a to the photoelectric conversion element 203 side is desirable.

Further, the wavelength of red is transmitted to a depth of about 2000 nm in the inner layer 203a of the image sensor. Therefore, it is desirable that the condensing position of the microlens 201a be the image sensor layer interior 203a in accordance with this. Table 5 also shows the light receiving sensitivity when the focal depth of the red microlens 201a is changed from 0 nm to 3500 nm. Moreover, the graph of the result is shown in Red (upper) of FIG.
As is apparent from the graph, it was found that the focal depth of the red lens microlens 201a had a peak between 2000 nm and 2500 nm. For this reason, the focal depth of the micro lens 201a of the red pixel is 2000 nm or more and 2500 nm or less from the surface of the photoelectric conversion element 203 on the micro lens 201 side in the photoelectric conversion element 203 toward the film thickness direction of the photoelectric conversion element 203. The position, that is, the position of 2000 nm or more and 2500 nm or less from the boundary surface between the photoelectric conversion element 203 and the planarization layer 3a toward the photoelectric conversion element 203 side is desirable.

Based on the above examination, in the image sensor of the sixth embodiment, the focal depth of the microlens 201 (201c) on the blue pixel is from the boundary surface with the planarization layer 3a of the photoelectric conversion element 203 to the photoelectric conversion element 203 side. The focal depth of the microlens 201 (201b) on the green pixel is set to a position of 200 nm or more and 500 nm or less, and the depth of focus is 600 nm or more and 900 nm or less from the boundary surface with the planarization layer 3a of the photoelectric conversion element 203 to the photoelectric conversion element side. The focal depth of the micro lens 201 (201a) on the red pixel is set to a position of 2000 nm or more and 2500 nm or less from the boundary surface with the planarization layer 3a of the photoelectric conversion element 203 to the photoelectric conversion element 203 side. ing.
According to the image sensor of the sixth embodiment, it is possible to collect light at the optimum depth of the image sensor by adjusting the focal depth of the microlens for each pixel. Thereby, the light receiving sensitivity is improved.

(Example 11)
In Example 11, the image sensor of Embodiment 4 was manufactured by the same method as in Example 8 described above.
As a result of measuring the light receiving sensitivity of each pixel, the light receiving sensitivity of red is 66.1%, the light receiving sensitivity of green is 57.5%, and the light receiving sensitivity of blue is 41.1% (Example 11 in Table 5). Improvement was confirmed for the light receiving sensitivity (the leftmost example in Table 5) with the same lens focal depth of 0 nm for all pixels. If necessary, a process such as bleaching may be performed to control the shape and light transmittance of the microlens.
As in the above-described eighth embodiment, the microlenses obtained in the present embodiment 11 are formed with microlenses having different heights at the same pitch as shown in FIG.

(Example 12)
In Example 12, the image sensor of Embodiment 6 was manufactured by the same method as in Example 9 described above.
As a result of measuring the light receiving sensitivity of each pixel, the light receiving sensitivity of red is 65.5%, the light receiving sensitivity of green is 57.7%, and the light receiving sensitivity of blue is 41.5% (Example 12 in Table 5). Improvement was confirmed for the light receiving sensitivity (the leftmost example in Table 5) with the same lens focal depth of 0 nm for all pixels.

In addition, if necessary, steps such as heat flow and bleaching can be performed to control the shape and light transmittance of the microlens. In the photolithography method using the gray tone mask 50 of this embodiment, when a KrF laser is used, the curved surface shape of the microlens can be controlled from a curvature diameter of 120 nm to 248 nm by the wavelength limit resolution of the KrF laser. It becomes.
As described above, according to the image sensor according to the sixth embodiment of the present invention, it is possible to collect light at the optimum depth of the image sensor by optimizing the focal depth of the microlens for each pixel. . Thereby, the light receiving sensitivity can be improved.

Further, according to the method of manufacturing the image sensor according to any one of Example 11 and Example 12 of the present invention, the depth of focus for each pixel in the photolithography process using the gray-tone mask is compared with Embodiment 6 of the present invention. Different microlens shapes can be easily and collectively formed.
Further, according to the method for manufacturing an image sensor of any one of Example 11 and Example 12, microlens shapes having different heights for each pixel can be easily and collectively formed by a photolithography process using the gray tone mask 9. Therefore, the manufacturing cost can be reduced compared to the conventional multiple etching methods and multiple resist patterning methods.

In addition, by using ultraviolet i rays for photolithography, it becomes possible to control the curved surface shape of the microlens from a curvature diameter of 180 nm to 365 nm, which is effective in improving the light collection efficiency of a microlens having a pixel size of about 1100 nm. is there.
Further, by using a KrF laser, the curved surface shape of the microlens can be controlled from a curvature diameter of 120 nm to 248 nm, which is effective in improving the light collection efficiency of the microlens having a pixel size of 1000 nm or less.
Although the invention made by the present inventor has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course.

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Photoelectric conversion element 3, 3a Flattening layer 4, 4a Color filter layer 4R Red (R) filter 4G Green (G) filter 4B Blue (B) filter 5 Micro lens 5a Vertex 6, 6A Solid-state image sensor 7 Bottom Pulling layer 8a Transmitted light arrival position at the pixel portion of the blue (B) filter 8b Transmitted light arrival position at the pixel portion of the green (G) filter 8c Transmitted light arrival position at the pixel portion of the red (R) filter 9 Gray tone Mask 101 Micro lens 101a Blue lens micro lens 101b Green pixel micro lens 101c Red pixel micro lens 101d Green pixel and red pixel height difference 101e Blue pixel and green pixel height difference 102 Color separation filter (color filter)
102a Red pixel color separation filter 102b Green pixel color separation filter 102c Blue pixel color separation filter 103 Photoelectric conversion element 103a Blue transmitted light arrival area 103b Green transmitted light arrival area 103c Red transmitted light arrival area 104 Silicon wafer 104a Semiconductor substrate 105 External connection pad (electrode pad)
106 Connection bump (solder bump)
111 Photosensitive microlens material 111a Microlens 112 Transparent resin layer 112a Microlens 113 Photosensitive sacrificial layer 113a Lens matrix 120 First gray tone mask 121 Density gradation pattern corresponding to green pixel 130 Second gray tone mask 131 Density gradation pattern corresponding to the blue pixel 132 Density gradation pattern corresponding to the red pixel 140 First photoresist layer 141 Second photoresist layer 150 Gray tone mask 201 Micro lens 201a Micro lens 201b of red pixel 201b Micro lens 201c Blue pixel micro lens 202 Color separation filter (color filter)
202a Red pixel color separation filter 202b Green pixel color separation filter 202c Blue pixel color separation filter 203 Photoelectric conversion element 203a Red transmitted light arrival area 203b Green transmitted light arrival area 203c Blue transmitted light arrival area 204a Semiconductor substrate 205 External connection pad (electrode pad)
206 Connection bump (solder bump)

Claims (18)

A semiconductor substrate;
A plurality of photoelectric conversion elements formed on the semiconductor substrate, wherein the photoelectric conversion elements are arranged in a matrix in the plane of the semiconductor substrate;
A planarization layer formed on the semiconductor substrate so as to cover the plurality of photoelectric conversion elements;
An undercoat layer formed on the planarizing layer;
A color filter layer formed on the undercoat layer, comprising a plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements, a red (R) filter, a green (G) filter, and A color filter layer having a blue (B) filter;
A plurality of microlenses formed respectively on the plurality of color filters;
With
The undercoat layer is
The focal point of the micro lens in the pixel portion of the red (R) filter is a position of 2000 nm or more and 2500 nm or less from the boundary surface with the planarization layer of the photoelectric conversion element, and the pixel portion of the green (G) filter. The focal point of the microlens is a position of 600 nm to 900 nm from the boundary surface with the planarization layer of the photoelectric conversion element, and the focal point of the microlens in the pixel portion of the blue (B) filter is the photoelectrical element. A solid-state imaging device formed to have a thickness of 200 nm or more and 500 nm or less from a boundary surface between the conversion element and the planarization layer. The solid-state imaging device according to claim 1, wherein the transmittance of the undercoat layer is 90% or more in a wavelength range of 300 nm to 800 nm. Between the adjacent color filter layers, a partition wall is provided upright at a position corresponding to the space between the photoelectric conversion elements, and the partition wall has a refractive index lower than that of the color filter layer. The solid-state imaging device according to claim 1. 4. The solid-state imaging device according to claim 1, wherein vertices of the micro lenses on the red (R), green (G), and blue (B) color filter layers have substantially the same height. 5. . A planarization layer forming step of forming a planarization layer on the semiconductor substrate so as to cover a plurality of photoelectric conversion elements formed on the semiconductor substrate and arranged in a matrix within the surface of the semiconductor substrate;
An undercoat layer forming step of forming an undercoat layer on the planarizing layer;
A color filter comprising a plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements on the undercoat layer, and having a red (R) filter, a green (G) filter, and a blue (B) filter A color filter layer forming step of forming a layer;
A microlens forming step of forming a plurality of microlenses on the plurality of color filters, respectively.
Including
The undercoat layer forming step is performed by forming a liquid layer containing a transparent photosensitive resin on the planarizing layer and then photocuring the liquid layer by a photolithography method using a gray tone mask.
The thickness of the undercoat layer immediately below the red (R) filter is the interface between the focal point of the microlens in the pixel portion of the red (R) filter and the planarization layer of the photoelectric conversion element. To a thickness of 2000 nm to 2500 nm.
The thickness of the undercoat layer immediately below the green (G) filter is the interface between the focal point of the microlens at the pixel portion of the green (G) filter and the planarization layer of the photoelectric conversion element. From 600 nm to 900 nm in thickness,
The thickness of the undercoat layer immediately below the blue (B) filter is the interface between the focal point of the microlens at the pixel portion of the blue (B) filter and the planarization layer of the photoelectric conversion element. The manufacturing method of the solid-state image sensor made into thickness which becomes 200 nm or more and 500 nm or less position from. In the undercoat layer forming step, the surface of the undercoat layer is obtained by changing the transmittance of the gray tone mask at each position of the red (R) filter, the green (G) filter, and the blue (B) filter. The manufacturing method of the solid-state image sensor of Claim 5 which controls the thickness in the inside. The solid-state imaging device manufacturing method according to claim 6, further comprising a partition wall step formed at a location corresponding to the space between the photoelectric conversion elements after the planarization layer forming step. A semiconductor substrate;
A plurality of photoelectric conversion elements formed on the semiconductor substrate, wherein the photoelectric conversion elements are arranged in a matrix in the plane of the semiconductor substrate;
A planarization layer formed on the semiconductor substrate so as to cover the plurality of photoelectric conversion elements;
An undercoat layer formed on the planarizing layer;
A color filter layer formed on the undercoat layer, comprising a plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements, and includes red (R), green (G), and blue (B ), And a color filter layer having an infrared (IR) filter;
A plurality of microlenses formed respectively on the plurality of color filters;
The undercoat layer comprises
The focal point of the microlens in the pixel portion of the red (R) filter is a position of 2000 nm to 2500 nm from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side,
The focal point of the microlens in the pixel portion of the green (G) filter is a position of 600 nm to 900 nm from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side,
The focal point of the microlens in the pixel portion of the blue (B) filter is a position of 200 nm to 500 nm from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side,
The focal point of the microlens in the pixel portion of the infrared (IR) filter is formed at a thickness of 1500 nm to 5000 nm from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side. A solid-state imaging device. 9. The solid-state imaging according to claim 8, wherein the red (R), green (G), blue (B), infrared (IR), and vertexes of the microlenses on each filter layer are substantially the same height. element. A planarization layer forming step of forming a planarization layer on the semiconductor substrate so as to cover a plurality of photoelectric conversion elements formed on the semiconductor substrate and arranged in a matrix within the surface of the semiconductor substrate;
An undercoat layer forming step of forming an undercoat layer on the planarizing layer;
It comprises a plurality of color filters arranged in the same matrix as the plurality of photoelectric conversion elements on the undercoat layer, and includes a red (R) filter, a green (G) filter, a blue (B) filter, and an infrared ray (IR) ) A color filter layer forming step of forming a color filter layer having a filter;
A microlens forming step of forming a plurality of microlenses on the plurality of color filters, respectively.
Including
The undercoat layer forming step is performed by forming a liquid layer containing a transparent photosensitive resin on the planarizing layer and then photocuring the liquid layer by a photolithography method using a gray tone mask.
The thickness of the undercoat layer immediately below the red (R) filter is the interface between the focal point of the microlens in the pixel portion of the red (R) filter and the planarization layer of the photoelectric conversion element. The thickness from 2000 nm to 2500 nm to the photoelectric conversion element side,
The thickness of the undercoat layer immediately below the green (G) filter is the interface between the focal point of the microlens at the pixel portion of the green (G) filter and the planarization layer of the photoelectric conversion element. The thickness from 600 nm to 900 nm to the photoelectric conversion element side,
The thickness of the undercoat layer immediately below the blue (B) filter is the interface between the focal point of the microlens at the pixel portion of the blue (B) filter and the planarization layer of the photoelectric conversion element. The thickness from 200 nm to 500 nm to the photoelectric conversion element side,
The thickness of the undercoat layer immediately below the infrared (IR) filter is the boundary surface between the microlens focal point at the pixel portion of the infrared (IR) filter and the planarization layer of the photoelectric conversion element. The manufacturing method of the solid-state image sensor made into the thickness used as the position which is 1500 nm or more and 5000 nm or less from the photoelectric conversion element side. In the undercoat layer forming step, the transmittance of the gray tone mask is changed for each of the red (R) filter, the green (G) filter, the blue (B) filter, and the infrared (IR) filter. The method for manufacturing a solid-state imaging device according to claim 10, wherein the thickness in the plane of the pulling layer is controlled. On the semiconductor substrate, at least a photoelectric conversion element and a microlens are laminated in this order, and each pixel of green, blue and red is formed for each photoelectric conversion element as a unit,
The microlens height on the green pixel is in the range of 105% to 150%, and the microlens height on the red pixel is in the range of 95% to 70%. A solid-state imaging device characterized by the above. On the semiconductor substrate, at least a photoelectric conversion element, a planarization layer, a color separation filter and a microlens are laminated in this order,
As the color separation filter, for each photoelectric conversion element as a unit, either a green pixel, a blue pixel, or a red pixel is formed,
As the micro lens, a green pixel micro lens, a blue pixel micro lens, and a red pixel micro lens corresponding to the green pixel, the blue pixel, and the red pixel, respectively, are formed.
The focal depth of the micro lens of the blue pixel is at a position of 200 nm or more and 500 nm or less from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side,
The focal depth of the microlens of the green pixel is at a position of 600 nm or more and 900 nm or less from the boundary surface with the planarization layer of the photoelectric conversion element to the photoelectric conversion element side,
The solid-state imaging device, wherein a focal depth of the micro lens of the red pixel is in a position of 2000 nm or more and 2500 nm or less from a boundary surface with the planarization layer of the photoelectric conversion device to the photoelectric conversion device side. It is a manufacturing method of the solid-state image sensing device according to claim 12 or 13,
A method of manufacturing a solid-state imaging device, wherein the microlenses having different heights are collectively formed by photolithography using a gray tone mask. Forming the photoelectric conversion element on the semiconductor substrate;
Applying a photosensitive microlens material on the photoelectric conversion element;
Patterning the photosensitive microlens material by photolithography using the gray tone mask; and
The manufacturing method of the solid-state image sensor of Claim 14 containing at least. Forming the photoelectric conversion element on the semiconductor substrate;
Applying a transparent resin layer over the entire surface of the photoelectric conversion element;
Applying a photosensitive sacrificial layer on the transparent resin layer;
Forming a lens matrix by patterning the photosensitive sacrificial layer by a photolithography method using the gray tone mask;
An etching transfer step of forming the microlens by etching the lens matrix and the transparent resin layer from above the lens matrix;
The manufacturing method of the solid-state image sensor of Claim 14 containing at least. A method for producing the solid-state imaging device according to claim 12,
Forming a microlens on the green pixel using a first gray tone mask;
Forming a microlens on the blue pixel and a microlens on the red pixel using a second graytone mask,
In the second gray tone mask, the transmittance at the center of the pattern corresponding to the blue pixel is smaller than the transmittance at the center of the pattern corresponding to the green pixel of the first gray tone mask.
Further, in the second gray tone mask, the transmittance at the center of the pattern corresponding to the red pixel is larger than the transmittance at the center of the pattern corresponding to the green pixel of the first gray tone mask. A method for manufacturing a solid-state imaging device. The method for manufacturing a solid-state imaging device according to any one of claims 14 to 17, wherein an ultraviolet i ray or a KrF laser is used for a photolithography method using the gray tone mask.

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