JP2000260970A - Solid-state imaging device and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] By effectively utilizing light incident on a gap region between lenses without causing fusion of lenses,
Provided is a solid-state imaging device with higher sensitivity and a method for manufacturing the same. A flattening layer provided with a groove surrounding the light receiving portion is provided on a substrate on which a plurality of light receiving portions are formed, and a convex lens and a groove are provided outside the groove of the flattening layer. Has a concave lens 15 therein. With this structure, light incident on the convex lens is condensed on the light receiving portion, and light incident on the concave lens is also refracted by the concave lens and incident on the light receiving portion, so that the sensitivity of the solid-state imaging device is improved and smear is reduced Leads to. The lenses do not fuse due to the presence of the groove.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid-state imaging device such as a CCD (Charge Coupled Device) having a convex lens (microlens) and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a general solid-state imaging device. A light receiving unit (photodiode) 6 is provided on the semiconductor substrate,
There are a transfer section 7 for transferring the electric charge of the light receiving section, a light shielding film 4 for preventing light from entering the transfer section, and the like. A color filter 3 is formed on the light-shielding film via an intermediate layer at a position corresponding to the light receiving section. A flattening layer 2 made of a transparent resin is formed thereon. In such a structure, there is a problem that a 100% area on the semiconductor substrate cannot be used as a light receiving unit.

As a method of solving this problem, a convex lens (microlens) 1 is formed on each light receiving portion to optically refract incident light and efficiently use the incident light to the light receiving portion. ing. FIG. 4 shows a general method of forming a convex lens. First, a positive resist 1 is placed on the planarizing layer 2.
1 (see FIG. 4A). After prebaking, exposure (see FIG. 4B) and development are performed, and a pattern is formed at a position corresponding to each light receiving section (pixel) (FIG. 4C).
reference). When the resist is heated, it is deformed into a convex lens by the surface tension (see FIG. 4D).

[0004]

In order to improve the utilization of incident light by using a convex lens, it is necessary to increase the opening area of the convex lens. For this purpose, it is necessary to reduce the distance between the convex lenses (the gap between the lenses) shown at 12 in FIG. The control factors of the gap between the lenses may include a patterning dimension, an exposure condition, a thermal reflow temperature, and the like.However, when a narrower gap is to be obtained, a lens pattern adjacent to the adjacent lens is deformed by the thermal reflow. Are fused and the sensitivity is reduced.

[0005] Due to this problem, if microlenses are manufactured under the condition that fusion of the microlenses does not occur, a gap between the lenses exists between the microlenses.
The light that has entered the area of the gap between the lenses goes straight as it is, enters the light-shielding part, which is not the light-receiving part, and does not contribute to the sensitivity because it is diffusely reflected. In addition, the light leaks to the transfer part and causes smear. Becomes As the elements of the solid-state imaging device are subdivided for higher pixel size and smaller size, it becomes necessary to effectively use light incident on the gap between lenses in order to improve sensitivity.

SUMMARY OF THE INVENTION The present invention solves such a problem. A solid-state image pickup device having higher sensitivity can be provided by preventing light fusion of a lens and effectively utilizing light incident on a gap region between lenses. The manufacturing method is provided.

[0007]

According to a first aspect of the present invention, there is provided a substrate having a plurality of light receiving portions formed thereon, comprising a flattening layer provided with a groove surrounding each light receiving portion, and A solid-state imaging device having a convex lens outside the groove of the planarization layer and a concave lens inside the groove.

According to a second aspect of the present invention, a flattening layer having a groove surrounding each light receiving portion is provided on a substrate on which a plurality of light receiving portions are formed, and the groove of the flattening layer is provided. A method for manufacturing a solid-state imaging device comprising a convex lens outside and a concave lens in a groove, wherein a concave lens forming pattern is formed by a positive resist in a groove, and the concave lens is formed by thermally reflowing the pattern. A method for manufacturing a solid-state imaging device, comprising at least a forming step.

According to a third aspect of the present invention, a flattening layer having a groove surrounding each light receiving portion is provided on a substrate on which a plurality of light receiving portions are formed, and the groove of the flattening layer is provided. A method for manufacturing a solid-state imaging device comprising a convex lens outside and a concave lens in a groove, wherein a pattern for forming a convex lens and a pattern for forming a concave lens in a groove are formed simultaneously outside the groove by a positive resist. A method for manufacturing a solid-state imaging device, comprising at least a step of forming a convex lens and a concave lens by thermally reflowing a pattern.

According to a fourth aspect of the present invention, based on the second and third aspects, a positive resist for forming a concave lens has the same or a higher refractive index than a positive resist for forming a convex lens. A method for manufacturing a solid-state imaging device, comprising:

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a solid-state imaging device according to the present invention,
A convex lens is manufactured for each light receiving section, and a concave lens is manufactured between adjacent convex lenses. Light incident on the convex lens is condensed on the light receiving unit, and light incident on the concave lens is also refracted by the concave lens and incident on the light receiving unit. And reduces smear.

Embodiment 1 FIG. 1 is a sectional view of a solid-state imaging device according to a first embodiment of the present invention. As a pre-process of lens formation, a planarizing layer 2 is provided on a substrate on which a plurality of light receiving portions are formed, and a groove 13 surrounding each light receiving portion is formed by a technique such as dry etching. In the case of this embodiment, the planar shape of the groove is a right-angle lattice.

Then, after a resist for a convex lens (microlens), which is a positive type resist, is applied on the flattening layer having the groove formed thereon, mask exposure and development are performed to form a convex lens forming pattern outside the groove of the flattening layer. To form When a heat treatment is performed on this pattern, heat reflow occurs to form a convex lens. However, since the groove 13 exists, each convex lens 1 does not fuse (see FIG. 1A).

Next, a resist for a concave lens, which is a positive resist, is applied to the flattening layer, and then mask exposure and development are performed to form a concave lens forming pattern 14 having a size that fits in the groove (FIG. 1 (b)). )reference). When heat treatment is performed on this pattern, thermal reflow occurs and the concave lens 15 is formed due to the effect of meniscus generated in the groove (FIG. 1C).
reference). If the positive resist for forming the concave lens has a higher refractive index than the positive resist for forming the convex lens, light incident on the boundary of the image will be refracted greatly toward the photodiode, and It is preferable because the use efficiency of the styrene becomes higher.

The solid-state image sensor manufactured in this manner has about 15% improvement in sensitivity as compared with a conventional solid-state image sensor without a groove, a concave lens, and the like.

In the above-mentioned embodiment, the manufacturing method in which the convex lens is formed by thermal reflow has been described. However, the convex lens may be formed by dry etching.

Embodiment 2 FIG. 2 is a sectional view of a solid-state imaging device according to a second embodiment of the present invention. As in Example 1,
A groove is formed in the planarization layer. Then, when a resist for a lens is applied and a pattern is formed, a concave lens forming pattern 16 serving as a concave lens is formed in the groove in addition to the convex lens forming pattern serving as a convex lens formed outside the groove (FIG. 2). (A)). By performing the heat treatment in this state, the convex lens and the concave lens 17 can be simultaneously formed (see FIG. 2B). The manufacturing method of the second embodiment has an advantage that the number of steps can be reduced as compared with the first embodiment.

The solid-state imaging device manufactured as described above has about 15% improvement in sensitivity as compared with a conventional solid-state imaging device having no grooves, concave lenses, and the like.

[0019]

As is clear from the above description, according to the solid-state imaging device of the first aspect, convex lenses corresponding to respective light receiving portions are manufactured, and concave lenses are manufactured between adjacent convex lenses. is there. With this structure, light incident on the convex lens is focused on the light receiving unit, and light incident on the concave lens is also refracted by the concave lens and incident on the light receiving unit. Accordingly, even light that could not be used conventionally can be effectively used, which improves the sensitivity of the solid-state imaging device and reduces smear. In addition, since there is a groove, each lens does not fuse.

According to the method for manufacturing a solid-state imaging device according to the second and third aspects, the number of steps of patterning and heat reflow of the resist for the concave lens is smaller than that of manufacturing the concave lens by a method such as dry etching. There is an advantage that you can. Further, since a concave lens is formed in the gap between lenses, a convex lens can be manufactured with a margin in the gap between lenses. This prevents fusion of adjacent convex lenses in the production of convex lenses, and improves production stability.

Further, according to the method of manufacturing a solid-state imaging device according to the fourth aspect, by using a material having a high refractive index for the concave lens, the light incident on the boundary of the pixel is largely refracted toward the photodiode. That is, the light use efficiency is further improved.

[0022]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a method for manufacturing a solid-state imaging device according to the present invention (Example 1).

FIG. 2 is an explanatory diagram illustrating a method (Example 2) for manufacturing a solid-state imaging device according to the present invention.

FIG. 3 is an explanatory diagram of a conventional solid-state imaging device.

FIG. 4 is an explanatory view showing a conventional microlens manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Convex lens 2 Flattening layer 3 Color filter 4 Light shielding part 5 Polysilicon 6 Light receiving part 7 Transfer part 13 Groove part 14 Concave lens forming pattern 15 Concave lens 16 Lens forming pattern 17 Concave lens

Claims (4)

[Claims] 1. A flattening layer having a groove surrounding each light receiving portion is provided on a substrate on which a plurality of light receiving portions are formed, and a convex lens is formed outside the groove of the flattening layer, and the flattening layer is formed inside the groove. A solid-state imaging device having a concave lens. 2. A substrate having a plurality of light receiving portions formed thereon, a flattening layer having a groove surrounding each light receiving portion is provided, and a convex lens outside the groove of the flattening layer, and a flattening layer formed in the groove. A method for manufacturing a solid-state imaging device having a concave lens, comprising at least a step of forming a concave lens forming pattern by a positive resist in a groove portion and thermally reflowing the pattern to form a concave lens. A method for manufacturing a solid-state imaging device, comprising: 3. A flattening layer having a groove surrounding each light receiving portion on a substrate on which a plurality of light receiving portions are formed, and a convex lens outside the groove of the flattening layer and a flat lens inside the groove. A method for manufacturing a solid-state imaging device, characterized by having a concave lens, wherein a pattern for forming a convex lens outside a groove portion by a positive resist and a pattern for forming a concave lens inside a groove portion are simultaneously formed,
A method for manufacturing a solid-state imaging device, comprising at least a step of forming a convex lens and a concave lens by thermally reflowing both patterns. 4. The method according to claim 2, wherein the positive resist for forming the concave lens has the same or a higher refractive index than the positive resist for forming the convex lens. .