JP2009295967A - Solid-state imaging element - Google Patents

Abstract

A solid-state imaging device capable of suppressing shading and having high sensitivity over the entire pixel region is provided.
A plurality of light receiving units, a functional layer formed on the plurality of light receiving units, and a plurality of micro lenses formed on the functional layer and corresponding to the plurality of light receiving units. In the solid-state imaging device, when the state in which the center position of the microlens 6 and the center position of the light receiving unit coincide with each other in plan view is set as the reference state, the center position of the microlens 6 is set to the reference state. Compared with the center position of the microlens 6 in FIG. 2, the center distance of the microlens 6 is shifted in the center direction of the pixel area. When the shift distance defined from the theoretical position at which the principal ray incident on the center position of the microlens 6 passes through the functional layer and reaches the center position of the light receiving portion is the theoretical principal ray shift distance, the above theory It is within a range shorter than the beam shift distance.
[Selection] Figure 6

Description

  The present invention relates to a solid-state imaging device that can effectively improve a shading state in an outer peripheral portion of a pixel region that is particularly affected by shading.

  The body of a digital camera that has been rapidly spreading in recent years incorporates a solid-state image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor that converts subject light into an optical signal and records an image. It is. Such a solid-state imaging device generally improves a light receiving portion that receives subject light and converts it into a photoelectric signal, a color filter layer formed on the light receiving portion, and a light collection rate on the light receiving portion. A microlens.

  In such a solid-state imaging device, a phenomenon called shading occurs in which the signal output at the outer peripheral portion is attenuated compared to the central portion of the pixel region. This shading is caused by incident light incident on the outer peripheral portion of the pixel region at an angle and the photoelectric conversion efficiency is deteriorated, and incident light incident at an angle is kicked by a light shielding layer, a wiring layer, or the like. In order to improve them, for example, as shown in FIG. 34, the light receiving portion 1, the inorganic device layer 2 (passivation layer, light shielding layer, wiring layer, interlayer insulating layer, etc.), the first planarizing layer 3, the color filter layer 4, the second In the solid-state imaging device in which the two planarization layers 5 and the microlenses 6 are stacked in this order, the microlens 6 has been shifted from the light receiving unit 1 toward the center side.

  Regarding the setting of the shift distance, as can be seen in Patent Documents 1 and 2, a method of determining the shift distance of the microlens using Snell's law is disclosed (for example, FIG. 1 of Patent Document 1). The ray tracing from the center of the exit pupil of the camera lens to the center of the micro lens is performed based on Snell's law, and the shift distance of the micro lens is set so that the ray enters the center of the light receiving unit. is there. Further, the chief ray incident angle at which the light from the camera lens enters the imaging region is determined by the image height (that is, the distance from the center of the pixel region to the light receiving unit) as shown in FIG. For example, as shown in FIG. 36, the shift distance (X direction and Y direction) of the light receiving portion of the Nth pixel from the center of the pixel region on the X axis or the Y axis is obtained. However, the influence of the aberration that occurs as the incident angle of the light ray incident on the microlens increases (that is, at the outer periphery of the pixel region) is not taken into consideration. In simple ray tracing, an appropriate shift distance can be set. There is a problem in that an appropriate shift distance cannot be set at the outer periphery of the pixel area that cannot be particularly effectively improved for shading improvement. Patent Document 2 discloses a method for obtaining a shift distance by calculation without the above-described ray tracing.

JP 2003-18476 A JP 2001-160973 A

  The present invention has been made in view of the above circumstances, and it is a main object of the present invention to provide a solid-state imaging device that can effectively improve a shading state in an outer peripheral portion of a pixel region that is particularly affected by shading. To do.

  In order to solve the above problems, in the present invention, a plurality of light receiving portions, a functional layer formed on the plurality of light receiving portions, and a plurality formed on the functional layer and corresponding to the plurality of light receiving portions. A center position of the microlens when a state in which the center position of the microlens and the center position of the light receiving unit coincide with each other in a plan view is a reference state. Is shifted in the center direction of the pixel region compared to the center position of the microlens in the reference state, and the shift distance by shifting the center position of the microlens in the center direction of the pixel region is the emission distance of the camera lens. The shift distance specified from the theoretical position where the chief ray incident from the center of the pupil to the center position of the microlens passes through the functional layer and reaches the center position of the light receiving unit is defined as the theoretical chief ray shift distance. If, to provide a solid-state imaging device, characterized in that within a range shorter than a distance shifted the theoretical principal ray.

  According to the present invention, by setting the shift distance by which the center position of the microlens is shifted in the center direction of the pixel region to be within a range shorter than the theoretical principal ray shift distance, the microlens can be obtained from the viewpoint of light intensity in the light receiving unit. Since the shift distance of the microlens is set in consideration of the influence of the aberration of the shading, the shading state can be improved. In addition, since the shift distance of the microlens is set according to the incident angle of light, the shading state can be effectively improved particularly in the outer peripheral portion of the pixel region where the influence of shading is large.

  In the above invention, it is preferable that the shift distance of the microlens is a shift distance such that a region having an incident light intensity level higher than the incident light intensity level at the theoretical position is the center of the light receiving unit. As a result, the relative intensity level of light at the center position of the light receiving unit is increased, and the shading state can be improved more effectively.

  In the above invention, the shift distance of the microlens is preferably within a range in which a higher hit rate can be obtained than when the microlens is shifted by the theoretical principal ray shift distance. This is because the shading state can be improved more effectively.

  In the invention described above, it is preferable that the microlens has a characteristic in which coma aberration occurs in the center direction of the pixel region. This is because the shading state can be improved more effectively.

In the above invention, the theoretical principal ray shifting distance is the following relational expression when the microlens and the functional layer are combined into an m-layer laminated member, and the microlens is the first layer of the m-layer laminated member: It is preferable that it is prescribed | regulated by 1).
S _m = Σ _{j = 1} ^m d _j tan θ _j ... Relational expression (1)
(Where S _m is the theoretical principal ray shifting distance, d _j is the thickness of the j layer, θ _j = sin ⁻¹ ((n _j−1 / n _j ) sin θ _j−1 ), n _j is the j layer The refractive index, n ₀ is the refractive index of the atmosphere (n ₀ = 1), and θ ₀ is the chief ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens)
Since this calculation method calculates the theoretical principal ray shift distance using the refractive index and thickness of each member constituting the m-layer constituent member, the theoretical principal ray shift distance can be defined with high accuracy.

In the above invention, the theoretical principal ray shifting distance is the following relational expression when the microlens and the functional layer are combined into an m-layer laminated member, and the microlens is the first layer of the m-layer laminated member. It is preferable that it is prescribed | regulated by (2).
S _m = tan θ ₁ Σ _{j = 1} ^m d _j ... (2)
Where S _m is the theoretical principal ray shifting distance, _dj is the thickness of the j layer, θ ₁ = sin ⁻¹ ((n ₀ / n ₁ ) sin θ ₀ ), n ₁ is the refractive index of the microlens, n ₀ is the refractive index of the atmosphere (n ₀ = 1), and θ ₀ is the principal ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens)
In this calculation method, the theoretical principal ray shift distance can be easily obtained. For example, when the refraction of the principal ray by the functional layer is small, the theoretical principal ray shift distance can be accurately defined.

  In the above invention, it is preferable that at least one of the functional layer constituting layers constituting the functional layer is shifted in the center direction of the pixel region. This is because the shading state can be further improved.

  In the above invention, the functional layer constituting layer shifted in the center direction of the pixel region is preferably a color filter layer. This is because the manufacturing process of the color filter layer is simpler than the manufacturing process of the inorganic device layer, so that the design is easy and the effect of improving the shading state is great.

  In the said invention, it is preferable that the said functional layer is an inorganic device layer, a 1st planarization layer, a color filter layer, and a 2nd planarization layer in order from the said light-receiving part side. This is because a general-purpose solid-state imaging device can be obtained.

  In the invention, the solid-state imaging device is formed by shifting only the microlens, and the shift distance of the microlens is greater than 38% of the theoretical principal ray shift distance and less than 100% of the theoretical principal ray shift distance. It is preferable to be within. This is because the shading state can be more effectively improved within the above range.

  In the invention described above, a solid-state imaging device having a color filter layer as a functional layer constituting layer constituting the functional layer, wherein the color filter layer is shifted in a center direction of the pixel region, and a shift distance of the microlens Is preferably larger than 65% of the theoretical principal ray shifting distance and smaller than 100% of the theoretical principal ray shifting distance. This is because the shading state can be more effectively improved within the above range.

  In the invention, the functional layer constituting layer constituting the functional layer has a color filter layer and an inorganic device layer, the inorganic device layer has a wiring layer or a light shielding layer, the color filter layer, and the inorganic layer A solid-state imaging device in which a wiring layer or a light shielding portion of a light shielding layer that is closest to the microlens in the device layer is shifted in the center direction of the pixel region. It is preferably within a range that is greater than 82% of the principal ray shift distance and less than 100% of the theoretical principal ray shift distance. This is because the shading state can be more effectively improved within the above range.

In the present invention, the functional layer constituting layers constituting the functional layer are all solid-state imaging devices that are shifted in the center direction of the pixel region, and the shift distance of the microlens is the theoretical principal ray shift distance. It is preferably within a range of more than 85% and less than 100% of the theoretical principal ray shifting distance. This is because the shading state can be more effectively improved within the above range. As will be described later, when the functional layer constituting layer has a transparent continuous layer such as a passivation layer, an interlayer insulating layer, a planarizing layer, etc., these do not have a boundary between adjacent pixels, so that they are appropriately shifted. It can be regarded as a thing. Here, the interlayer insulating layer in the present invention refers to a transparent continuous layer such as a SiO ₂ layer (a layer having a spread in a direction (horizontal direction) perpendicular to the stacking direction). Therefore, a wiring layer having a metal wiring in the SiO _2, or the light-shielding layer or the like provided with metal light-shielding portion in the SiO within ₂ does not correspond to the interlayer insulating layer.

  The present invention is such that the shift distance by which the center position of the microlens is shifted in the center direction of the pixel region is within a range shorter than the theoretical principal ray shift distance, and the outer peripheral portion of the pixel region that is particularly affected by shading. With this, the shading state can be effectively improved.

FIG. 6 is a ray tracing diagram when parallel light is incident perpendicularly (incident angle = 0 °) with respect to the microlens of the solid-state imaging device. It is a graph which shows the relative intensity level of the light which injects into a light-receiving part on the conditions similar to FIG. 1 (F value = 2.8). It is a ray tracing figure in case parallel light injects with respect to the micro lens of a solid-state image sensor at the incident angle of 20 degrees. 4 is a graph showing a relative intensity level of light incident on a light receiving unit under the same conditions as in FIG. 3 (F value = 2.8). 4 is a graph showing a relative intensity level of light incident on a light receiving unit under the same conditions as in FIG. 3 (F value = 2.8, incident angle 30 °). It is a schematic sectional drawing explaining the shift distance of the micro lens in this invention. It is a schematic plan view explaining the shift distance of the microlens in this invention. It is a schematic sectional drawing explaining the center of a pixel area. It is a schematic sectional drawing explaining the calculation method of the theoretical principal ray shifting distance by optical simulation. An example of an optical simulation that determines the probability (relative value) that a light hits the center of a microlens when the light incident on the center of the microlens passes through the functional layer and reaches the light receiver. is there. It is explanatory drawing explaining an example of the micro lens used for this invention. It is a SEM photograph of the microlens shown in FIG. FIG. 6 is a ray tracing diagram when parallel light is incident on the microlens of the solid-state imaging device according to the first embodiment at a predetermined incident angle. It is explanatory drawing explaining the simulation in this invention. 6 is a graph showing the hit rate when the chief ray incident angle is 20 ° in Example 1. 6 is a graph showing the hit rate when the chief ray incident angle is 30 ° in Example 1. 6 is a graph showing an evaluation of a change in shading state depending on a value in Example 1. FIG. 10 is a ray tracing diagram when parallel light is incident on the microlens of the solid-state imaging device according to the second embodiment at a predetermined incident angle. It is a graph which shows the hit rate in Example 2 in case the chief ray incident angle is 20 degrees. It is a graph which shows the hit rate in Example 2 in case the chief ray incident angle is 30 degrees. 6 is a graph showing an evaluation of a change in shading state depending on a value in Example 2. FIG. 10 is a ray tracing diagram when parallel light is incident at a predetermined incident angle on the microlens of the solid-state imaging element according to the third embodiment. It is a graph which shows the hit rate in Example 3 in case the chief ray incident angle is 20 degrees. It is a graph which shows the hit rate in Example 3 in case the chief ray incident angle is 30 degrees. 10 is a graph showing an evaluation of a change in shading state depending on a value in Example 3. FIG. 10 is a ray tracing diagram when parallel light is incident at a predetermined incident angle on the microlens of the solid-state imaging element according to the fourth embodiment. It is a graph which shows the hit rate in Example 4 in case the chief ray incident angle is 20 degrees. It is a graph which shows the hit rate in the case of Example 4 in case the chief ray incident angle is 30 degrees. It is the graph which evaluated the change of the shading state by the value of a in Example 4. FIG. FIG. 10 is a ray tracing diagram when parallel light is incident on the microlens of the solid-state imaging device in Example 5 at a predetermined incident angle. It is a graph which shows the hit rate in Example 5 in case the chief ray incident angle is 20 degrees. It is a graph which shows the hit rate in Example 5 in case the chief ray incident angle is 30 degrees. 10 is a graph showing an evaluation of a change in shading state depending on a value in Example 5. It is explanatory drawing explaining the shift of a micro lens. It is explanatory drawing explaining the shift of a micro lens. It is explanatory drawing explaining the shift of a micro lens. It is a figure for demonstrating the basic concept of the shift distance of the micro lens by this invention.

  Hereinafter, the solid-state imaging device of the present invention will be described in detail.

  The solid-state imaging device of the present invention includes a plurality of light receiving units, a functional layer formed on the plurality of light receiving units, a plurality of microlenses formed on the functional layer and corresponding to the plurality of light receiving units, When the state where the center position of the microlens coincides with the center position of the light receiving portion in a plan view is set as the reference state, the center position of the microlens is set to the reference state. Compared to the center position of the microlens at the center of the pixel area, the shift distance by shifting the center position of the microlens toward the center of the pixel area is from the center of the exit pupil of the camera lens to the microlens. When the shift distance specified from the theoretical position where the principal ray incident on the center position of the light beam passes through the functional layer and reaches the center position of the light receiving unit is the theoretical principal ray shift distance, It is characterized in that within a range shorter than the linear displacement distance.

  According to the present invention, by setting the shift distance by which the center position of the microlens is shifted in the center direction of the pixel region to be within a range shorter than the theoretical principal ray shift distance, the microlens can be obtained from the viewpoint of light intensity in the light receiving unit. Since the shift distance of the microlens is set in consideration of the influence of the aberration of the shading, the shading state can be improved. In addition, since the shift distance of the microlens is set according to the incident angle of light, the shading state can be effectively improved particularly in the outer peripheral portion of the pixel region where the influence of shading is large. Note that Patent Document 2 describes that a range of ± 30% is allowed for the optimum value of the shift distance obtained by optical simulation (for example, paragraph 0047 of Patent Document 2). However, this only allows an error of ± 30% in consideration of calculation omission and approximation, and actual manufacturing accuracy. On the other hand, the present invention sets the range of the shift distance of the microlens in consideration of the influence of aberration, and the shift distance is the optimum shift distance using the expression of the above-mentioned Patent Document 2. It is a short range for the value. Such a concept is neither described nor suggested in Patent Document 2. In other words, since there has been no known shift of the micro lens in consideration of the influence of the aberration, it is naturally difficult to determine whether the influence of the aberration is longer or shorter than the optimum value of the shift distance. there were. On the other hand, in the present invention, the shift distance of the microlens is set based on the knowledge that the influence of the aberration appears on the short side with respect to the optimum value of the shift distance. That is, in the present invention, the shift distance of each microlens is set based on the new finding that the incident light intensity level on the short side becomes higher than the optimum shift distance due to the influence of aberration. It is.

Next, the concept of the solid-state imaging device of the present invention will be described in order with reference to the drawings. First, FIG. 1 is a ray tracing diagram in the case where parallel light is incident on the microlens of the solid-state imaging device at a vertical angle (incident angle = 0 °). More specifically, an inorganic device layer (seven SiO ₂ layers (three layers of which are a wiring layer or a light shielding layer, and the remaining four layers are interlayer insulating layers) and a passivation layer) on a light receiving portion having a pitch of 2 μm) FIG. 6 is a ray tracing diagram in the case of using a solid-state imaging device in which a first planarization layer, a color filter layer, a second planarization layer, and a microlens (gapless continuous type) are stacked. Note that the wiring layer or the light shielding layer shown in FIG. 1 has the same film thickness between the wiring portion or the light shielding portion (shaded portion in the drawing) and the transmission portion (transparent portion in the drawing). Therefore, the interface between adjacent SiO ₂ layers (interlayer insulating layers) is formed in a straight line with no step between the wiring portion or the light shielding portion and the transmission portion. In actual manufacture, the film thickness of the wiring part or the light shielding part is smaller than the film thickness of the transmission part, and a part of the transmission part may remain on the surface of the wiring part or the light shielding part. When forming a wiring layer or a light shielding layer, the wiring part or the light shielding part is first formed, and then the transmission part is formed by a CVD method or the like so as to cover the wiring part or the light shielding part. However, during the flattening process, wiring is performed without performing flattening until the film thickness of the wiring part or the light-shielding part completely matches the film thickness of the transmission part. This is because the planarization may be finished to the extent that a part of the transmission part remains on the surface of the part or the light shielding part. Even when there is such a mismatch in film thickness, the error due to the mismatch is slight and can be ignored in the optical simulation.

  As shown in FIG. 1, the incident parallel light passes through the microlens and other layers, and is focused on the surface of the light receiving unit. Here, FIG. 2 is a diagram showing the relative intensity level of light incident on the light receiving unit under the same conditions as in FIG. 1, and the numerical values in the figure represent the relative intensity of incident light. However, the light beam incident on the microlens is not parallel light but a light beam incident from a camera lens having an F value = 2.8. The relative intensity level of the light shown in FIG. 2 is not parallel light, so it does not converge on one point and has a certain spread, but the point where the light beam passing through the center of the microlens reaches (the cross-shaped point in FIG. 2). It has a circular spread that is symmetrical in the vertical and horizontal directions with the center portion as the center.

On the other hand, FIG. 3 is a ray tracing diagram when parallel light is incident on the microlens of the solid-state imaging device at an incident angle of 20 °. Here, as will be described later, the layers constituting the microlens, the second planarization layer, the color filter layer, the first planarization layer, and the inorganic device layer are shifted by a predetermined shift distance with respect to the light receiving portion. Shall. As shown in FIG. 3, when the incident angle of the parallel light is increased, the parallel light is not collected at one point on the light receiving unit as shown in FIG. 1, but is incident on the center position of the microlens from the center of the exit pupil of the camera lens. The principal ray passes through the functional layer and reaches the center position of the light receiving unit (a point indicated by symbol A in FIG. 3; hereinafter, also expressed as “theoretical position”), that is, below the drawing, that is, in the pixel region It can be seen that a light beam reaching the center direction is observed. This can be presumed to be a phenomenon in which the influence of so-called “coma aberration” appears strongly among the aberrations considered to be possessed by the microlens.
Hereinafter, the effect of this coma aberration on the light intensity distribution in the light receiving portion of the solid-state imaging device will be described.

  FIG. 4 is a diagram showing the relative intensity level of light incident on the light receiving unit under the same conditions as in FIG. 3, and the numerical values in the figure represent the relative intensity of incident light. However, the light beam incident on the microlens is not parallel light but a light beam incident from a camera lens having an F value = 2.8. FIG. 5 is a diagram when the incident angle is changed to 30 °. As understood from the relative intensity levels of the light shown in these figures, the spread of the light beam incident from the camera lens is distorted in the vertical direction, and the portion with the high incident light intensity level (FIGS. 4 and 4). 5 is an area from 0.8 to 1.0) below the point from the point where the chief ray passing through the center of the microlens reaches the light receiving part (the central part of the cross in FIGS. 4 and 5), that is, the pixel area As the chief ray incident angle increases, the amount of shift in a region with a high incident light intensity level also increases. As described above, the microlens used in the solid-state imaging device has a characteristic in which coma aberration occurs in the center direction of the pixel region, that is, a region where the incident light intensity level of light incident on the light receiving unit is high in the center direction of the pixel region. It has a deviating characteristic.

  As described above, the new knowledge in the present invention has been specifically described with reference to FIGS. That is, as described above, in the present invention, the incident light intensity level on the short side (near the center direction of the pixel region) is higher than the optimum value of the shift distance considered conventionally due to the influence of the aberration of the microlens. This is a new finding. A major feature of the present invention is that the shift distance of the microlens (the positional relationship between a certain microlens and the corresponding light receiving unit) is set based on this new knowledge.

  Therefore, the shift distance of the microlens in the present invention is that the light ray incident on the center of the microlens is traced based on Snell's law from the center of the exit pupil of the camera lens, and the light ray is incident on the center of the light receiving unit. Rather than setting in this way, the setting is made in consideration of aberrations that have not been considered in the past. That is, the major feature of the present invention is that the microlens shift distance in the present invention is set in consideration of a region where the incident light intensity level is high due to the influence of the aberration of the microlens.

  More specifically, the shift distance of the microlens is a region having an incident light intensity level higher than the incident light intensity level at the above-described theoretical position (the point represented by the central portion of the cross in FIGS. 4 and 5). It is set to be the center of the light receiving part.

FIG. 37 is a diagram for explaining the basic concept of the shift distance of the microlens in the present invention. In FIG. 37, the solid line represents the incident light intensity level corresponding to FIG. 4, the symbol x represents the center position of the light receiving unit, and the symbol + represents the theoretical position described above (the center portion of the cross in FIGS. 4 and 5). ing. As shown in FIG. 37, the center position (symbol x) of the light receiving unit is shifted from the above-described theoretical position (symbol +) toward the center of the pixel region to be a position in a region where the incident light intensity level is higher. It is. Thereby, the center position of the light receiving unit is set not in the region where the incident light intensity level is 0.6 to 0.8 but in the region where the incident light intensity level is 0.8 to 1.0. Here, the “region” is not a region in a strict sense, but means a place (part) where the incident light intensity level is relatively higher than the above-described theoretical incident light intensity level. It is. By setting the shift distance of each microlens in this manner, the relative intensity level of light at the center position of the light receiving unit is increased, and the shading state is improved. In particular, it is possible to effectively improve the shading state at the outer peripheral portion of the pixel area where the influence of shading is large. An example of how to determine the shift distance of the micro lens is a range in which a higher hit rate can be obtained than when the micro lens is shifted by the theoretical principal ray shift distance. A method for determining the shift distance of the microlens using this hit rate will be described later.
Hereinafter, the solid-state imaging device of the present invention will be described in more detail.

1. Regarding the positional relationship between the microlens and the light receiving unit First, the positional relationship between the microlens and the light receiving unit in the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic cross-sectional view for explaining the positional relationship between the microlens and the light receiving portion in the present invention, and FIG. 7 is a schematic plan view thereof. In the solid-state imaging device of the present invention, when the state in which the center position of the microlens and the center position of the light receiving unit coincide with each other in the plan view is the reference state, the center position of the microlens is Compared with the center position of the microlens, it is shifted toward the center of the pixel region. Here, the “center position of the microlens” refers to the position of the center of gravity on the ground contact surface of the microlens. The “center position of the light receiving portion” refers to the position of the center of gravity on the photosensitive surface of the light receiving portion. The “reference state” refers to a state in which the center position of the microlens and the center position of the light receiving unit coincide in plan view, and specifically, as shown in FIGS. 6 (a) and 7 (a). In addition, the center position of the microlens 6 and the center position of the light receiving unit 1 coincide with each other in plan view.

  As described above, in the present invention, the center position of the microlens is shifted in the center direction of the pixel region compared to the center position of the microlens in the reference state. Here, the “center of the pixel region” refers to a position where the optical axis of the camera lens and the pixel region intersect. Specifically, as shown in FIG. 8, the optical axis of the camera lens and the solid-state imaging device 10 The position where the pixel area intersects. The “center direction of the pixel region” is not limited to a straight line connecting the center of the light receiving unit and the center of the pixel region in a plan view, but also includes a direction in which the above-described aberration affects. Is.

  On the other hand, in the present invention, the “theoretical principal ray shifting distance” is the theoretical amount by which the principal ray incident on the center position of the microlens from the center of the exit pupil of the camera lens passes through the functional layer and reaches the center position of the light receiving unit. It is defined from the right position. Usually, it is determined by the thickness and refractive index of the microlens and the functional layer. As described above, the technique of shifting the microlens based on the position where the chief ray reaches the light receiving unit has been conventionally performed (see FIGS. 6B and 7B).

  On the other hand, the shift distance of the microlens in the present invention is characterized by being in a range shorter than the theoretical principal ray shift distance. Specifically, as shown in FIGS. 6C and 7C, the shift distance of the microlens 6 is usually the theoretical principal ray shift distance and the shift distance (shift amount) of the microlens in the reference state. = 0). When the microlens is displaced by the microlens displacement distance in the present invention, the principal ray reaches a position deviating from the center position of the light receiving unit 1 as shown in FIG. Even in such a case, as described with reference to FIGS. 3 to 5 and 37 described above, since the center position of the light receiving unit is set to a region having a relatively high incident light intensity level, the light at the center position of the light receiving unit is set. The relative intensity level of becomes stronger.

  As described above, the microlens in this embodiment has a characteristic in which coma aberration occurs in the center direction of the pixel region (that is, a region having a high incident light intensity level of light incident on the light receiving unit is in the center direction of the pixel region. Those having a characteristic of shifting) are preferably used. An example of the shape of such a microlens is a shape obtained by cutting a part of a spheroid. Here, “coma aberration” is classified as one of Seidel's five aberrations, and refers to an aberration in which a light beam emitted from one point outside the optical axis does not converge to one point on the image plane. Is a comet shape asymmetric with respect to the chief ray. As for coma aberration, for example, “Practical Light Keyword Dictionary” (issued in October 2005, edited by Japan Optical Measuring Instruments Manufacturers Association, Asakura Shoten) and “Optics” (issued in October 1979, by Kazumi Murata, Science) Are described in detail. However, the microlens in this embodiment has a characteristic in which coma aberration occurs in the center direction of the pixel area (that is, a characteristic in which an area having a high incident light intensity level of light incident on the light receiving unit is shifted in the center direction of the pixel area). It is not limited to only having “coma aberration” in the meaning defined in the above dictionary.

  The theoretical principal ray shifting distance in the present invention varies depending on the configuration of the solid-state imaging device and is preferably calculated by optical simulation. Among them, in the present invention, it is preferable to define the theoretical principal ray shift distance by one of the following two types of calculation methods.

First, the first calculation method of the theoretical principal ray shifting distance in the present invention will be described. In this calculation method, the theoretical principal ray shifting distance is defined by the following relational expression (1) when the microlens and the functional layer are combined into an m-layer laminated member and the microlens is the first layer of the m-layer laminated member. It is what is done.
S _m = Σ _{j = 1} ^m d _j tan θ _j ... Relational expression (1)
(Where S _m is the theoretical principal ray shifting distance, d _j is the thickness of the j layer, θ _j = sin ⁻¹ ((n _j−1 / n _j ) sin θ _j−1 ), n _j is the j layer The refractive index, n ₀ is the refractive index of the atmosphere (n ₀ = 1), and θ ₀ is the chief ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens)

In this calculation method, the principal ray incident at the chief ray incident angle from the center of the exit pupil of the camera lens to the center of the microlens is incident to the microlens at the boundary of both sides of the boundary in the state of a predetermined specific optical system. Refracted according to the difference in refractive index of the material, and then refracted according to the difference in refractive index on both sides of the boundary each time it passes through the boundary between different materials, taking an optical path to the center of the light receiving unit This is a method for obtaining the theoretical principal ray shift distance. Specifically, as shown in FIG. 9, in the state of a specific optical system such as a microlens and a functional layer (second planarization layer, color filter layer, first planarization layer, and inorganic device layer), the camera lens Corresponding to the difference in refractive index of the material (atmosphere and microlens) on both sides of the boundary at the boundary where the chief ray incident at the chief ray incident angle θ ₀ from the exit pupil center to the center of the microlens enters the microlens The theoretical principal ray shifting distance S is assumed assuming that each time the light passes through the boundary between different materials, it is refracted corresponding to the difference in refractive index on both sides of the boundary and takes an optical path to the center of the light receiving unit. _This is a method for obtaining _m . Since this calculation method calculates the theoretical principal ray shift distance using the refractive index and thickness of each member constituting the m-layer constituent member, the theoretical principal ray shift distance can be defined with high accuracy.

Relational expression (1) is obtained as follows (see FIG. 9).
First, the microlens and the functional layer are collectively used as an m-layer laminated member, and the microlens is defined as the first layer of the m-layer laminated member. In addition, the value of m is in the range of 1-10, for example. Furthermore, n ₀ is the refractive index of the atmosphere (n ₀ = 1), n ₁ is the refractive index of the microlens, and θ ₀ is the principal ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens. , Θ ₁ is the emission angle of the chief ray emitted from the microlens. According to Snell's law, n ₀ , n ₁ , θ ₀ , and θ ₁ have the following relationship.
n ₀ sin θ ₀ = n ₁ sin θ ₁
Therefore, θ ₁ = sin ⁻¹ ((n ₀ / n ₁ ) sin θ ₀ ).
Similarly, θ _{j at} the interface between the j−1 layer and the j layer (the emission angle of the chief ray emitted from the j layer) is θ _j = sin ⁻¹ ((n _j−1 / n _j ) sin θ _j−1 ). It becomes.
Further, since the shift amount dS ₁ of the microlens (the shift amount of the microlens with respect to the second flattening layer as the second layer) is dS ₁ / d ₁ = tan θ ₁ , dS ₁ = d ₁ tanθ ₁ .
Similarly, the shift amount dS _j of the _j layer with respect to the j−1 layer is dS _j = d _j tan θ _j .
Here, when the theoretical principal ray shifting distance is S _m , S _m is the accumulation of dS _j from the first layer to the m layer.
S _m = Σ _{j = 1} ^m dS _j = Σ _{j = 1} ^m d _j tan θ _j

Next, a second calculation method of the theoretical principal ray shifting distance in the present invention will be described. In this calculation method, the theoretical principal ray shifting distance is defined by the following relational expression (2) when the microlens and the functional layer are combined into an m-layer laminated member and the microlens is the first layer of the m-layer laminated member. It is what is done.
S _m = tan θ ₁ Σ _{j = 1} ^m d _j ... (2)
Where S _m is the theoretical principal ray shifting distance, _dj is the thickness of the j layer, θ ₁ = sin ⁻¹ ((n ₀ / n ₁ ) sin θ ₀ ), n ₁ is the refractive index of the microlens, n ₀ is the refractive index of the atmosphere (n ₀ = 1), and θ ₀ is the principal ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens)

  This calculation method uses a boundary at which the principal ray incident at the chief ray incident angle from the center of the exit pupil of the camera lens to the center of the microlens enters the microlens in the state of a predetermined specific optical system. This is a method for obtaining the theoretical principal ray shifting distance on the assumption that the light is refracted corresponding to the difference in refractive index between the materials on both sides, then travels straight, and takes the optical path to the center of the light receiving portion. This calculation method uses the refractive index of the atmosphere and the refractive index of the microlens located in the first layer of the m-layer constituent member to determine the emission angle of the principal ray emitted from the microlens, and then the emission angle. In this method, the theoretical principal ray shift distance is calculated from the thickness of each member constituting the m-layer constituent member under the assumption that the principal ray goes straight and passes through the functional layer. In this calculation method, the theoretical principal ray shift distance can be easily obtained. For example, when the refraction of the principal ray by the functional layer is small, the theoretical principal ray shift distance can be accurately defined.

Relational expression (2) is obtained as follows.
First, the microlens and the functional layer are collectively used as an m-layer laminated member, and the microlens is defined as the first layer of the m-layer laminated member. In addition, the value of m is in the range of 1-10, for example. Furthermore, n ₀ is the refractive index of the atmosphere (n ₀ = 1), n ₁ is the refractive index of the microlens, and θ ₀ is the principal ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens. , Θ ₁ is the emission angle of the chief ray emitted from the microlens. Here, according to Snell's law, n ₀ , n ₁ , θ ₀ , and θ ₁ have the following relationship.
n ₀ sin θ ₀ = n ₁ sin θ ₁
Therefore, θ ₁ = sin ⁻¹ ((n ₀ / n ₁ ) sin θ ₀ ).
Here, since it is assumed that the chief ray emitted from the microlens goes straight through the functional layer,
S _m = tan θ ₁ × (total thickness of m layer constituent members) = tan θ ₁ Σ _{j = 1} ^m d _j .

  In the present invention, the shift distance of the microlens is shorter than the theoretical principal ray shift distance. Furthermore, in the present invention, it is preferable that the shift distance of the microlens is within a range in which a higher hit rate can be obtained than when the microlens is shifted by the theoretical principal ray shift distance. FIG. 10 shows an example of the light hit rate obtained by optical simulation when light incident on the center of the microlens from a predetermined angle passes through the functional layer and reaches the light receiving unit. As will be described later, the shift distance when the value of a is 100% corresponds to the theoretical principal ray shift distance. In the present invention, the shift distance of the microlens is in a range shorter than the theoretical principal ray shift distance. Furthermore, it is preferable that the shift distance of the microlens is within a range in which a higher hit rate can be obtained than when the microlens is shifted by the theoretical principal ray shift distance. In FIG. 10, if the shift distance of the micro lens is within a range that is greater than 85% of the theoretical principal ray shift distance and less than 100% of the theoretical principal ray shift distance, the micro lens is shifted by the theoretical principal ray shift distance. A higher hit rate than the case can be obtained. In the solid-state imaging device of the present invention, it is preferable to shift the microlens within such a range.

  In particular, the range of the shift distance of the microlens is, for example, 1% or more, especially 5% or more, particularly 10% or more higher than the hit rate when the microlens is shifted by the theoretical principal ray shift distance. A range is preferred. This is because the shading state can be improved more effectively.

  In the present invention, the shift distance of the microlens varies greatly depending on the configuration of the solid-state imaging device. The details of the shift distance of the microlens will be described in detail in “3. Shift of each layer constituting the functional layer” described later.

  In the present invention, a microlens array is formed by arranging a plurality of microlenses. In the present invention, among the microlenses constituting the microlens array, the microlens belonging to the above-described predetermined shift distance range is preferably 50% or more, more preferably 75% or more, More preferably, it is 90% or more. In particular, in the present invention, it is preferable that all the microlenses constituting the microlens array belong to the predetermined shift distance range described above. On the other hand, in the present invention, it is preferable that the microlens located in the outer peripheral portion of the pixel region where the influence of shading is large is in the range of the predetermined shift distance described above. When the entire area of the pixel area is divided into a rectangular central area including the center of the pixel area and an outer peripheral area located around the central area, in the present invention, the outer peripheral area of the pixel area having a large influence of shading. It is preferable that the microlens located in the range of the predetermined shift distance described above. In this case, the length of one side of the central region is preferably 70% or less, particularly 50% or less, particularly 30% or less, with respect to the length of one side of the corresponding pixel region.

  In the present invention, the microlens may be shifted, the light receiving unit may be shifted, or both the microlens and the light receiving unit may be shifted within the range of the predetermined shift distance described above.

2. Next, members used for the solid-state imaging device used in the present invention will be described. The solid-state imaging device of the present invention typically includes a plurality of light receiving units, a functional layer formed on the plurality of light receiving units, and a plurality of microlenses formed on the functional layer and corresponding to the plurality of light receiving units. And have.

  The microlens used in the present invention is not particularly limited as long as it has a function of condensing incident light and causes aberrations with respect to oblique light. As an example of the microlens used in the present invention, for example, as shown in FIGS. 11 and 12, the upper surface has a shape obtained by cutting out a part of a spheroid, the bottom surface is flat, and is adjacent. Examples include a shape having no gap at the boundary with the microlens. FIG. 12 is an SEM photograph of the microlens shown in FIG. Such a shape is an ideal shape from the viewpoint of light collection efficiency, and a design and manufacturing method of such a microlens are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2004-70087 and 2004-296590. As described above, in the present invention, it is preferable to use the microlens shown in FIGS. 11 and 12 for the solid-state imaging device shown in FIG. The reason is that if the microlens has a shape obtained by cutting out a part of the spheroid, spherical aberration can be obtained. The microlens shown in FIGS. 1 and 9 and the like is one in which the AA ′ direction cross section and the CC ′ direction cross section are superimposed and displayed as shown in the cross sectional view of FIG.

  The light receiving unit used in the present invention is not particularly limited, and the same light receiving unit as that used in a general solid-state image sensor can be used. Usually, a photodiode is used as the light receiving portion. In addition, as the substrate that supports the light receiving unit, the same substrate as that used in a general solid-state image sensor can be used.

The functional layer used in the present invention is a general term for layers arranged between a plurality of light receiving units and a plurality of microlens arrays, and the configuration thereof varies greatly depending on the configuration of the solid-state imaging device. The functional layer in the present invention usually has a multilayer structure. When each layer constituting the functional layer is a functional layer constituting layer, specific examples of the functional layer constituting layer include an organic layer and an inorganic device layer. Specific examples of the layer constituting the organic layer include a flattening layer, a color filter layer, an in-layer lens layer, and the like. Specific examples of the layer constituting the inorganic device layer include a passivation layer, an interlayer insulating layer (for example, SiO ₂ layer), a wiring layer, a light shielding layer, and the like. About these members, the thing similar to the member used for a general solid-state image sensor can be used.

  In the present invention, regardless of the configuration of the functional layer, the theoretical principal ray shifting distance can be defined by optical simulation based on the thickness and refractive index of each layer constituting the functional layer. Therefore, the layer structure of the functional layer is not particularly limited. Examples of the configuration of the functional layer in the present invention (in order from the light receiving unit side) include, for example, an inorganic device layer, a first planarization layer, a color filter layer, and a second planarization layer, a first planarization layer, and a color filter. The structure which is a layer and a 2nd planarization layer, the structure which is an inorganic device layer, a 1st planarization layer, an inner lens layer, a 2nd planarization layer, a color filter layer, and a 3rd planarization layer etc. can be mentioned. .

3. As described above, the solid-state imaging device according to the present invention is configured such that the center position of the microlens is compared with the center position of the microlens in the reference state described above in the center direction of the pixel region. That is, the shift distance is in a range shorter than the theoretical principal ray shift distance. Therefore, the functional layer (functional layer constituting layer) positioned between the microlens and the light receiving unit may be shifted by a predetermined shift distance or not at all. In particular, in the present invention, it is preferable that at least one of the functional layer constituting layers constituting the functional layer is shifted in the center direction of the pixel region. This is because the shading state can be further improved.

  From the viewpoint of improving the shading state, it is preferable that most of the functional layer constituting layers are shifted in the center direction of the pixel region, and all of the functional layer constituting layers are shifted in the center direction of the pixel region. It is more preferable. In addition, when the functional layer constituting layer has a transparent continuous layer such as a passivation layer, an interlayer insulating layer, a planarization layer, etc., since these do not have a boundary between adjacent pixels, they can be regarded as appropriately shifted. it can.

  On the other hand, from the viewpoint of facilitating the design of the solid-state imaging device, it is preferable that the functional layer constituting layer other than the inorganic device layer is shifted in the center direction of the pixel region. The reason why the design of the solid-state imaging device is facilitated is as follows. That is, the inorganic device layer usually has a wiring layer and a light shielding layer. If the wiring layer and the light shielding layer are arranged carelessly, the incident light is blocked. Therefore, it is necessary to avoid the optical path of the incident light collected by the microlens as much as possible. In other words, it is necessary to arrange the region that is not shielded by the wiring layer and the light shielding layer in consideration of the incident angle of the light beam, and in the same way as the microlens, the center of the region that is not shielded can be shifted in consideration of the principal ray incident angle. I need it. As a result, the design and manufacturing process of the inorganic device layer are complicated. In the present invention, as described above, the functional layer constituting layer other than the inorganic device layer is preferably shifted in the center direction of the pixel region, and in particular, the color filter layer is shifted in the center direction of the pixel region. More preferably. This is because the manufacturing process of the color filter layer is simpler than the manufacturing process of the inorganic device layer, so that the design is easy and the effect of improving the shading state is great.

The shift distance of the functional layer constituting layer can be calculated based on, for example, the relational expression (1) or the relational expression (2) described above. For example, in relational expression (1), the theoretical principal ray shift distance is obtained by combining the functional layer and the microlens as an m-layer laminated member. Using the relational expression, the theoretical principal ray shifting distance S _i of the _i - _th functional layer constituting layer of the m-layer laminated member can be obtained by S _i = Σ _{j = i} ^m d _j tan θ _j . Similarly, in the relational expression (2), the theoretical principal ray shifting distance S _i of the _i - _th functional layer constituting layer of the m-layer laminated member can be obtained by S _i = tan θ ₁ Σ _{j = i} ^m d _j it can. Note that the shift distance of the functional layer constituting layer may be calculated as S _iac = aS _i using the aberration coefficient a as in relational expression (I) described later. For example, when the range of a is 85% <a <100%, the shift distance of the functional layer constituting layer of the i-th layer of the m-layer laminated member is larger than 85% of the theoretical principal ray shift distance S _i , This means that it is within a small range of 100% of the theoretical principal ray shifting distance S _i . In Examples 1 to 5 described later, the shift distance between the microlens and each functional layer is the same as the Y-Shift value when a = 100% in Tables 2, 4, 5, 6, and 7. The value calculated by multiplying the value of a is used. However, the shift distance of each functional layer in the present invention does not necessarily have to be multiplied by the same value of a used for calculation of the shift distance of the microlens, and may be a different value.

  Here, consider a case where the solid-state imaging device of the present invention is a solid-state imaging device in which only the microlens is shifted. This is a case where the microlens is shifted and the functional layer is not shifted. In this case, the shifting distance of the microlens is, for example, larger than 38%, more preferably 45% or more, and particularly preferably 50% or more with respect to the theoretical principal ray shifting distance. Similarly, the shift distance of the microlens is preferably in a range that is usually less than 100%, particularly 95% or less, particularly 90% or less with respect to the theoretical principal ray shift distance.

  Next, consider a case where the solid-state image pickup device of the present invention is a solid-state image pickup device having a color filter layer as a functional layer constituting layer constituting the functional layer and the color filter layer being shifted in the center direction of the pixel region. This is a case where the microlens and the color filter layer are shifted, and the functional layers other than the color filter layer are not shifted. In this case, the shifting distance of the microlens is, for example, larger than 65% with respect to the theoretical principal ray shifting distance, more preferably 70% or more, and particularly preferably 80% or more. Similarly, the shift distance of the microlens is preferably in a range that is usually less than 100%, particularly 95% or less, particularly 90% or less with respect to the theoretical principal ray shift distance.

  Next, the solid-state imaging device of the present invention has a color filter layer and an inorganic device layer as a functional layer constituting layer constituting the functional layer, the inorganic device layer has a wiring layer or a light shielding layer, Consider a case in which the wiring layer or the light shielding portion of the light shielding layer located closest to the microlens in the inorganic device layer is a solid-state imaging device that is shifted in the center direction of the pixel region. This is a case where the light shielding portion of the wiring layer or the light shielding layer located closest to the microlens among the microlens, the color filter layer, and the inorganic device layer is shifted, and other functional layers are not shifted. Note that “shifting the light shielding portion” is, in other words, shifting the region that is not shielded by the wiring layer and the light shielding layer so as not to block the optical path of the incident light collected by the microlens. In this case, the shift distance of the microlens is preferably greater than 82%, for example, 85% or more, particularly 90% or more, relative to the theoretical principal ray shift distance. Similarly, the shift distance of the microlens is preferably in a range that is usually less than 100%, in particular 98% or less, especially 95% or less with respect to the theoretical principal ray shift distance.

  Next, consider a case where the solid-state imaging device of the present invention is a solid-state imaging device in which all of the functional layer constituting layers constituting the functional layer are shifted in the center direction of the pixel region. This is a case where the microlens and all of the functional layer constituting layers constituting the functional layer are shifted. In addition, as described above, when the functional layer constituting layer has a transparent continuous layer such as a passivation layer, an interlayer insulating layer, a planarization layer, etc., these do not have a boundary between adjacent pixels, so that they are appropriately shifted. It can be regarded as a thing. In this case, the shift distance of the microlens is, for example, greater than 85%, preferably 88% or more, with respect to the theoretical principal ray shift distance. Similarly, the shift distance of the microlens is preferably in a range that is usually less than 100%, particularly 95% or less, particularly 90% or less with respect to the theoretical principal ray shift distance.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration and exhibits the same function and effect regardless of the case. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described more specifically with reference to examples.
[Example 1]
An optical simulation was performed on the solid-state imaging device having the configuration shown in FIG. This solid-state imaging device has seven layers of SiO ₂ , a passivation layer, a first planarizing layer, a color filter layer, a second planarizing layer, and a microlens from the light receiving unit side. Further, in this solid-state imaging device, only the microlens is shifted in the center direction of the pixel region.

Based on the relational expression (1), the shift amount S _iac of the i-th layer can be defined by the following relational expression (I).
S _iaac = aΣ _{j = i} ^m d _j tan θ _j ... Relational expression (I)
(Where, a is an aberration coefficient, i is a natural number of 1 to _m , d _j is the thickness of the j layer, θ _j = sin ⁻¹ ((n _j−1 / n _j ) sin θ _j−1 ), n _j Is the refractive index of the j layer, n ₀ is the refractive index of the atmosphere (n ₀ = 1), and θ ₀ is the principal ray incident angle incident on the center position of the microlens from the center of the exit pupil of the camera lens)
When a = 1 (100%), the i-layer theoretical principal ray shift distance S _i is used. For example, when the range of a is 85% <a <100%, the shift distance of the micro lens is larger than 85% of the theoretical principal ray shift distance and is within a small range of 100% of the theoretical principal ray shift distance. Means that.

  Table 1 shows the simulation conditions.

  Note that “Infinity” in the radius of curvature in Table 1 means that the radius of curvature is infinite, that is, a flat surface. Further, as seen in FIG. 13, the light beam that has reached the outside of the area defined in 1) and 2) of Table 1 is considered to have been kicked.

ZEMAX-EE (Version April 2, 2004 rev.b) manufactured by ZEMAX Development Corporation was used as the simulation software. The calculation result (efficiency) on the software (ZEMAX) is processed as energy by taking into account the incident angle to the light receiving part, not simply the ratio of the number of input light rays and the number of light rays reaching the light receiving part. . That is, each light beam reaching the light receiving unit is multiplied by the incident angle COS to be treated as energy, and is represented as efficycy compared to the incident light energy. The hit rate is expressed as a ratio E ₂ / E ₁ between the energy E ₁ reaching the microlens surface when the chief ray incident angle is 0 ° and the energy E ₂ reaching the light receiving part under a predetermined condition. The For incident light, as shown in FIG. 14, the OBJECT surface on ZEMAX is set in contact with the microlens surface (first layer on ZEMAX). Think of this as a light source with uniform brightness (the size is a circle of radius √2 circumscribing it when the microlens is 2 × 2 μm □), and the angle of the ray from the OBJECT plane is from 0 ° to the camera lens Random in the range from the F value to the expected angle, and randomly generating light rays from the entire surface of the OBJECT surface (however, the light rays around the OBJECT surface are processed as shown in FIG. Not considered).

  Using the above relational expression (I), the theoretical principal ray shifting distance of the solid-state imaging device having the configuration shown in FIG. 13 was calculated. The results are shown in Table 2. Note that the value of Y-Shift in the table means the amount of shift in the vertical direction in FIG. 13, and is the amount of shift with respect to the center of the light receiving unit at the center of the microlens or the like. In Table 2, the Y-Shift value is also set for the second flattening layer. However, since the second flattening layer is usually a transparent continuous layer, it is regarded as being appropriately deviated. be able to.

  In Table 2, “CRA” means chief ray angle. The same applies to Tables 4 to 7 below. The hit rate was calculated using the relational expression (I) and the simulation conditions.

  FIG. 15 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 20 °. As shown in FIG. 15, at the chief ray incident angle of 20 °, the hit rate is maximum when the value of a is 75%, and the hit rate is improved by 25.8% when the value of a is 100%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 48% and smaller than 100%. When the value of a was in the range of 51% to 97%, the hit rate was improved by 5% or more than when the value of a was 100%. When the value of a was in the range of 54% to 95%, the hit rate was improved by 10% or more than when the value of a was 100%.

  FIG. 16 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 30 °. As shown in FIG. 16, at the chief ray incident angle of 30 °, the hit rate was maximum when the value of a was 70%, and the hit rate was improved by 220% compared to when the value of a was 100%. In addition, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 43% and smaller than 100%. When the value of a was in the range of 43% to 99%, the hit rate was improved by 10% or more than when the value of a was 100%.

  Moreover, the change of the shading state by the value of a was evaluated from the result obtained similarly. The result is shown in FIG. In this way, a preferable range of a can be set according to the chief ray incident angle incident from the center of the exit pupil of the camera lens.

[Example 2]
An optical simulation was performed on the solid-state imaging device having the configuration shown in FIG. This solid-state imaging device has two SiO ₂ layers, a passivation layer, a first planarizing layer, a color filter layer, a second planarizing layer, and a microlens from the light receiving unit side. Further, in this solid-state imaging device, only the microlens is shifted in the center direction of the pixel region, and the pixel size is larger than that in FIG.

  Table 3 shows the simulation conditions.

  Note that “Infinity” in the radius of curvature in Table 3 means that the radius of curvature is infinite, that is, a flat surface. Further, as seen in FIG. 13, the light beam that has reached the outside of the area defined in 1) and 2) of Table 1 is considered to have been kicked.

  Using the relational expression (I) used in Example 1, the theoretical principal ray shift distance of the solid-state imaging device having the configuration shown in FIG. 18 was calculated. The results are shown in Table 4. Note that the value of Y-Shift in the table means the shift amount in the vertical direction in FIG. 18, and is the shift amount with respect to the center of the light receiving unit at the center of the microlens or the like. In Table 4, the Y-Shift value is also set for the second flattening layer. However, since the second flattening layer is usually a transparent continuous layer, it is regarded as being appropriately deviated. be able to.

  The hit rate was calculated using the relational expression (I) and the simulation conditions.

  FIG. 19 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 20 °. As shown in FIG. 19, at the chief ray incident angle of 20 °, the hit rate was maximum when the value of a was 67%, and the hit rate was improved by 6.8% compared to when the value of a was 100%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 38% and smaller than 100%. When the value of a was in the range of 51% to 84%, the hit rate was improved by 5% or more than when the value of a was 100%.

  FIG. 20 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 30 °. As shown in FIG. 20, at the chief ray incident angle of 30 °, the hit rate is maximized when the value of a is 74%, and the hit rate is improved by 22% compared to when the value of a is 100%. In addition, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 45% and smaller than 100%. When the value of a was in the range of 48% to 96%, the hit rate was improved by 5% or more than when the value of a was 100%. When the value of a was in the range of 53% to 92%, the hit rate was improved by 10% or more than when the value of a was 100%.

  Moreover, the change of the shading state by the value of a was evaluated from the result obtained similarly. The result is shown in FIG. In this way, a preferable range of a can be set according to the chief ray incident angle incident from the center of the exit pupil of the camera lens.

[Example 3]
Optical simulation was performed on the solid-state imaging device having the configuration shown in FIG. This solid-state imaging device has seven layers of SiO ₂ , a passivation layer, a first planarizing layer, a color filter layer, a second planarizing layer, and a microlens from the light receiving unit side. Further, in this solid-state imaging device, the microlens and the color filter layer are shifted in the center direction of the pixel region.

  Using the relational expression (I) and simulation conditions used in Example 1, the theoretical principal ray shifting distance of the solid-state imaging device having the configuration shown in FIG. 22 was calculated. The results are shown in Table 5. Note that the value of Y-Shift in the table means the amount of shift in the vertical direction in FIG. Moreover, in Table 5, although the value of Y-Shift is set also to the 1st planarization layer, the 2nd planarization layer, and the passivation layer, since these layers are usually transparent continuous layers, It can be regarded as having shifted appropriately.

  The hit rate was calculated using the relational expression (I) and the simulation conditions.

  FIG. 23 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 20 °. As shown in FIG. 23, at a chief ray incident angle of 20 °, the hit rate was maximized when the value of a was 90%, and the hit rate was improved by 5.5% compared to when the value of a was 100%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 79% and smaller than 100%.

  FIG. 24 is a graph showing the hit rate (relative value) of light rays when the chief ray incident angle is 30 °. As shown in FIG. 24, at the chief ray incident angle of 30 °, the hit rate is maximized when the value of a is 85%, and the hit rate is improved by 35% compared to when the value of a is 100%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 65% and smaller than 100%. When the value of a was in the range of 67% to 98%, the hit rate was improved by 5% or more than when the value of a was 100%. When the value of a was in the range of 69% to 97%, the hit rate was improved by 10% or more than when the value of a was 100%.

  Moreover, the change of the shading state by the value of a was evaluated from the result obtained similarly. The result is shown in FIG. In this way, a preferable range of a can be set according to the chief ray incident angle incident from the center of the exit pupil of the camera lens.

[Example 4]
An optical simulation was performed on the solid-state imaging device having the configuration shown in FIG. This solid-state imaging device has seven layers of SiO ₂ , a passivation layer, a first planarizing layer, a color filter layer, a second planarizing layer, and a microlens from the light receiving unit side. Further, in this solid-state imaging device, the microlens, the color filter layer, and the light shielding layer are shifted in the center direction of the pixel region. In addition, the light shielding layer is shifted so that the area not shielded from light does not block the optical path of the incident light collected by the microlens.

Using the relational expression (I) and the simulation conditions used in Example 1, the theoretical principal ray shifting distance of the solid-state imaging device having the configuration shown in FIG. 26 was calculated. The results are shown in Table 6. Note that the value of Y-Shift in the table means the shift amount in the vertical direction in FIG. 26, and is the shift amount with respect to the center of the light receiving unit at the center of the microlens or the like. In Table 6, the Y-Shift value is also set for the first planarization layer, the second planarization layer, the passivation layer, and the SiO ₂ layer. These layers are usually transparent continuous layers. Therefore, it can be considered that it shifted | deviated appropriately.

  The hit rate was calculated using the relational expression (I) and the simulation conditions.

  FIG. 27 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 20 °. As shown in FIG. 27, at the chief ray incident angle of 20 °, the hit rate was maximum when the value of a was 94%, and the hit rate was improved by 2.3% compared to when the value of a was 100%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 88% and smaller than 100%.

  FIG. 28 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 30 °. As shown in FIG. 28, at the chief ray incident angle of 30 °, the hit rate is maximized when the value of a is 92%, and the hit rate is improved by 7.7% compared to when the value of a is 100%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 82% and smaller than 100%. When the value of a was in the range of 87% to 96%, the hit rate was improved by 5% or more than when the value of a was 100%.

  Moreover, the change of the shading state by the value of a was evaluated from the result obtained similarly. The result is shown in FIG. In this way, a preferable range of a can be set according to the chief ray incident angle incident from the center of the exit pupil of the camera lens.

[Example 5]
An optical simulation was performed on the solid-state imaging device having the configuration shown in FIG. This solid-state imaging device has seven layers of SiO ₂ , a passivation layer, a first planarizing layer, a color filter layer, a second planarizing layer, and a microlens from the light receiving unit side. Further, in this solid-state imaging device, all the functional layer constituting layers (seven SiO ₂ layers, passivation layer, first planarizing layer, color filter layer, and second planarizing layer) are shifted in the center direction of the pixel region. ing.

Using the relational expression (I) and the simulation conditions used in Example 1, the theoretical principal ray shifting distance of the solid-state imaging device having the configuration shown in FIG. 30 was calculated. The results are shown in Table 7. Note that the value of Y-Shift in the table means the amount of shift in the vertical direction in FIG. 30, and is the amount of shift with respect to the center of the light receiving unit at the center of the microlens or the like. In Table 7, the Y-Shift value is also set for the first planarization layer, the second planarization layer, the passivation layer, and the SiO ₂ layer, but these layers are usually transparent continuous layers. Therefore, it can be considered that it shifted | deviated appropriately.

  The hit rate was calculated using the relational expression (I) and the simulation conditions.

  FIG. 31 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 20 °. As shown in FIG. 31, at the chief ray incident angle of 20 °, the hit rate became maximum when the value of a was 95%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 88% and smaller than 100%.

  FIG. 32 is a graph showing the hit rate (relative value) of rays when the chief ray incident angle is 30 °. As shown in FIG. 32, at the chief ray incident angle of 30 °, the hit rate was maximum when the value of a was 93%. Further, the hit rate was larger than that when the value of a was 100% within a range where the value of a was larger than 85% and smaller than 100%.

  Moreover, the change of the shading state by the value of a was evaluated from the result obtained similarly. The result is shown in FIG. In this way, a preferable range of a can be set according to the chief ray incident angle incident from the center of the exit pupil of the camera lens.

[Discussion]
In Example 5, all the functional layers are shifted, and the number of functional layers shifted in the order of Example 4 and Example 3 is reduced. In Examples 1 and 2, only the microlens is shifted. The range of a having a high hit rate is closest to 100% in Example 5, and decreases in the order of Examples 4, 3, 1, 2, and the hit rate itself also decreases in this order. That is, when the number of functional layers to be shifted is small, it is considered that a phenomenon occurs in which the light beam is kicked at the boundary with the functional layers that are not shifted (for example, in FIG. 13, the light enters the color adjacent to the color filter layer). The rays are processed as kicked rays). Kicking has a large step between the shifting layer and the non-shifting layer (for example, the step in the vertical direction in the drawing between the microlens side surface of the second planarization layer and the microlens side surface of the color filter layer in FIG. 13). Naturally, it becomes large, and as a result, it is considered that the value is excessively shifted and it is advantageous that the value of a is small. In Examples 4 and 5, since the number of kicking elements is reduced, the effect of aberration is easily apparent, and good results are obtained when a = 90%.

DESCRIPTION OF SYMBOLS 1 ... Light-receiving part 2 ... 1st planarization layer 3 ... Color filter layer 4 ... 2nd planarization layer 5 ... Micro lens

Claims (13)

A solid-state imaging device comprising: a plurality of light receiving parts; a functional layer formed on the plurality of light receiving parts; and a plurality of microlenses formed on the functional layer and corresponding to the plurality of light receiving parts. ,
When the state in which the center position of the microlens and the center position of the light receiving unit coincide with each other in a plan view is set as the reference state, the center position of the microlens is compared with the center position of the microlens in the reference state. Shifted toward the center of the pixel area,
The shift distance by which the center position of the microlens is shifted in the center direction of the pixel region is such that the principal ray incident on the center position of the microlens from the center of the exit pupil of the camera lens passes through the functional layer and reaches the center position of the light receiving unit. A solid-state imaging device, wherein a shift distance defined from a theoretical position to reach is a theoretical principal ray shift distance, and is within a range shorter than the theoretical principal ray shift distance.   The shift distance of the micro lens is a shift distance such that a region having an incident light intensity level higher than the incident light intensity level at the theoretical position is the center of the light receiving unit. The solid-state imaging device described.   3. The solid according to claim 1, wherein the shift distance of the microlens is within a range in which a higher hit rate is obtained than when the microlens is shifted by the theoretical principal ray shift distance. Image sensor.   4. The solid-state imaging device according to claim 1, wherein the microlens has a characteristic in which coma aberration occurs in a center direction of the pixel region. 5. The theoretical principal ray shifting distance is defined by the following relational expression (1) when the microlens and the functional layer are combined into an m-layer laminated member, and the microlens is the first layer of the m-layer laminated member. The solid-state imaging device according to any one of claims 1 to 4, wherein the solid-state imaging device is provided.
S _m = Σ _{j = 1} ^m d _j tan θ _j ... Relational expression (1)
(Where S _m is the theoretical principal ray shifting distance, d _j is the thickness of the j layer, θ _j = sin ⁻¹ ((n _j−1 / n _j ) sin θ _j−1 ), n _j is the j layer The refractive index, n ₀ is the refractive index of the atmosphere (n ₀ = 1), and θ ₀ is the chief ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens) The theoretical principal ray shifting distance is defined by the following relational expression (2) when the microlens and the functional layer are combined into an m-layer laminated member, and the microlens is the first layer of the m-layer laminated member. The solid-state imaging device according to any one of claims 1 to 4, wherein the solid-state imaging device is provided.
S _m = tan θ ₁ Σ _{j = 1} ^m d _j ... (2)
Where S _m is the theoretical principal ray shifting distance, _dj is the thickness of the j layer, θ ₁ = sin ⁻¹ ((n ₀ / n ₁ ) sin θ ₀ ), n ₁ is the refractive index of the microlens, n ₀ is the refractive index of the atmosphere (n ₀ = 1), and θ ₀ is the principal ray incident angle incident from the center of the exit pupil of the camera lens to the center position of the microlens)   7. The solid-state imaging according to claim 1, wherein at least one of the functional layer constituting layers constituting the functional layer is shifted in a center direction of the pixel region. element.   8. The solid-state imaging device according to claim 7, wherein the functional layer constituting layer shifted in the center direction of the pixel region is a color filter layer.   The said functional layer is an inorganic device layer, a 1st planarization layer, a color filter layer, and a 2nd planarization layer in order from the said light-receiving part side, The any one of Claim 1-8 characterized by the above-mentioned. A solid-state imaging device according to claim. A solid-state imaging device in which only the microlens is displaced;
The shift distance of the microlens is in a range larger than 38% of the theoretical principal ray shift distance and smaller than 100% of the theoretical principal ray shift distance. A solid-state imaging device according to any one of the claims. A solid-state imaging device having a color filter layer as a functional layer constituting layer constituting the functional layer, wherein the color filter layer is shifted in a center direction of the pixel region;
7. The shift distance of the microlens is within a range that is greater than 65% of the theoretical principal ray shift distance and less than 100% of the theoretical principal ray shift distance. A solid-state imaging device according to any one of the claims. As the functional layer constituting layer constituting the functional layer, a color filter layer and an inorganic device layer are included. The inorganic device layer has a wiring layer or a light shielding layer. Among the color filter layer and the inorganic device layer, A solid-state imaging device in which a wiring layer or a light shielding part of a light shielding layer closest to the microlens is shifted in the center direction of the pixel region,
The shift distance of the microlens is within a range that is greater than 82% of the theoretical principal ray shift distance and less than 100% of the theoretical principal ray shift distance. A solid-state imaging device according to any one of the claims. A solid-state imaging device in which all of the functional layer constituting layers constituting the functional layer are shifted in the center direction of the pixel region,
The shift distance of the microlens is within a range that is greater than 85% of the theoretical principal ray shift distance and less than 100% of the theoretical principal ray shift distance. A solid-state imaging device according to any one of the claims.