JP2018082002A - Solid state imaging device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress sensitivity deterioration of the peripheral part for the central part, of a solid state imaging device such as a CCD or a CMOS sensor where microlenses are spread evenly.SOLUTION: In a solid state imaging device, when multiple unit regions of the same rectangular shape consisting of multiple unit microlens in a microlens group are set arbitrarily, numeric value of arrangement number ratio N1/N2 decreases as the distance r measured from the center location of the solid state imaging device increases, where N1 is the arrangement number of first unit microlens, i.e., the number of first unit microlens included in the unit region, and N2 is the arrangement number of second unit microlens, i.e., the number of second unit microlens included in the unit region.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid-state imaging device having a photoelectric conversion region divided for each pixel and a microlens group composed of unit microlenses corresponding to the pixels on a one-to-one basis, and measured from the center position of the solid-state imaging device. A solid-state imaging device capable of suppressing a decrease in sensitivity in the periphery of the solid-state imaging device having a long distance r measured from the center position of the solid-state imaging device with respect to the central portion of the solid-state imaging device having a short distance r, and an electronic device including the same Regarding equipment.

  In recent years, an increase in the number of pixels of an imaging device mounted on a video camera, a digital camera, or a mobile phone with a camera has been promoted. Along with pixel miniaturization of solid-state imaging devices such as CCDs and CMOS sensors incorporated in an imaging apparatus, there is a problem of sensitivity reduction due to a decrease in the amount of light incident on each pixel.

  In order to suppress a decrease in sensitivity, a method of forming unit microlenses on the incident side of the light receiving element so as to correspond to the pixels on a one-to-one basis is widely used. By forming the microlens, incident light can be efficiently collected on the photodiode, and the light receiving sensitivity can be improved (Patent Document 1).

  However, since the shape of a highly condensing microlens depends on the incident angle of incident light, it is optimal for the sensor center where the chief ray is incident vertically and the sensor periphery where the chief ray is incident at an angle. The lens shape is different.

  Therefore, when unit microlenses optimized under the condition that the chief ray is vertical are spread uniformly, even if the sensitivity is high enough in the center of the sensor, there is a problem that the sensitivity is insufficient in the periphery To do.

JP 2000-332226 A

  The present invention has been made in view of the above-described problems. The unit microlenses are uniformly spread, the photoelectric conversion regions divided for each pixel, and the units corresponding to the pixels one-to-one. An object of the present invention is to suppress a decrease in sensitivity of the peripheral portion of the solid-state imaging device with respect to the central portion of the solid-state imaging device such as a CCD or CMOS sensor having a microlens group including microlenses.

As means for solving the above-mentioned problem, the first aspect of the present invention includes a photoelectric conversion region divided for each pixel, and a microlens group including unit microlenses corresponding to the pixels one-to-one. A solid-state imaging device comprising:
The microlens group includes a first unit microlens made of a convex lens and a second unit microlens made of a Fresnel lens,
A first unit that is the number of first unit microlenses included in the unit region when a plurality of unit regions having the same rectangular shape including a plurality of unit microlenses are arbitrarily set in the microlens group. The arrangement number ratio N1 / N2 between the arrangement number N1 of the microlens and the arrangement number N2 of the second unit microlens that is the number of the second unit microlens included in the unit region is the center of the solid-state imaging device. The solid-state imaging device is characterized in that the numerical value becomes lower toward the periphery from.

  In the second aspect of the present invention, the first unit microlens is disposed in a region where the chief ray tilt angle of light incident on the solid-state imaging device is less than 10 °, and the chief ray tilt angle is 10 °. The solid state imaging device according to the first aspect, wherein the second unit microlens is disposed in the above region.

  According to a third aspect of the present invention, at least one of the first unit microlens and the second unit microlens is a bottom surface when viewed from the light incident side of the solid-state image sensor vertically. The solid-state imaging device according to the first or second aspect, characterized in that the shape is an ellipse.

  According to a fourth aspect of the present invention, at least one of the first unit microlens and the second unit microlens corresponds to a center position of a photoelectric conversion region divided for each pixel. The difference between the center positions of the unit microlenses is expressed by a difference function Δ (r) that is a function of a distance r measured from the center position of the solid-state imaging device. It is a solid-state image sensor of the 3rd mode.

  According to a fifth aspect of the present invention, there is provided an electronic apparatus including the solid-state imaging device according to any one of the first to fourth aspects.

  According to the present invention, it is possible to suppress a decrease in sensitivity of a peripheral portion having a long distance r measured from the center position of the solid-state image sensor of the microlens group with respect to a central portion having a short distance r measured from the center position of the solid-state image sensor of the microlens group. It was found that the light receiving sensitivity could be improved, and that the sensitivity improvement was particularly effective when the chief ray was tilted.

1A and 1B are schematic views illustrating an example of a solid-state imaging device including a microlens group according to an embodiment of the present invention, in which FIG. 1A is a schematic partial plan view of pixel arrangement, and FIG. 2B is a schematic portion of the solid-state imaging device. Sectional drawing (c) is a schematic plan view showing a part of a microlens group composed of a plurality of unit microlenses. It is typical sectional drawing showing the effect | action of a micro lens in embodiment and comparative form of this invention, (a) is typical partial sectional drawing of the solid-state image sensor which has the 1st unit micro lens which consists of a convex lens, (b) ) Is a schematic partial cross-sectional view of a solid-state imaging device having a first unit microlens made of a Fresnel lens. It is a schematic diagram showing the optical path in a camera optical system, (a) when the chief ray is irradiated perpendicularly to the surface of the solid-state image sensor, (b) is tilted with respect to the surface of the solid-state image sensor Is irradiated. It is a figure showing arrangement | positioning of the micro lens in embodiment of this invention, (a) is a notional top view of a solid-state image sensor, (b) is the center position of the photoelectric conversion area | region in the straight line Q of (a), and it respond | corresponds to it FIG. 4C is a conceptual cross-sectional view when the center position of the unit microlenses to be coincided with each other, and (c) is a case where the center position of the photoelectric conversion region on the straight line Q in (a) is shifted from the center position of the corresponding unit microlens. FIG. FIG. 4 is a conceptual cross-sectional view showing an example of a cross-sectional view of a unit microlens in an embodiment of the present invention, where (a) is a relief-type Fresnel lens and (b) is a binary-type Fresnel lens. It is. It is sectional drawing of a simulation model. It is a graph of incident angle and light receiving sensitivity when the image pitch is 5 μm. It is a graph of incident angle and light receiving sensitivity when the image pitch is 10 μm.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view (a) of a pixel arrangement showing an example of a solid-state imaging device 10 having a microlens, a cross-sectional view (b) of a solid-state imaging device 10 including a microlens group, and a plan view of a microlens group ( c), 1 is a substrate, 1a is a photoelectric conversion region, 2 is a wiring layer, 3 is wiring, 4 is a color filter, and 5 is a microlens group. Although FIG. 1 shows an example of a configuration having the color filter 4, a configuration in which the color filter is deleted and a first unit microlens 5 a made of a unit microlens, for example, a convex lens is directly disposed on the wiring layer 2. good.

  The light incident on the solid-state imaging device 10 is refracted by the first unit microlens 5a, further passes through the color filter 4, and the light corresponding to the color for each pixel passes through the wiring layer 2 to generate a photoelectric conversion region. Condensed to 1a. The photoelectric conversion region 1a is separated for each pixel, and electric charges generated by irradiating the photoelectric conversion region 1a with light flow to the electronic circuit and are read out as signals.

  The substrate 1 and the photoelectric conversion region 1a are made of silicon, for example. The wiring layer 2 is formed of silicon oxide, silicon nitride, or the like. The wiring 3 is formed of a metal such as aluminum, silver, chromium, or tungsten.

  The color filter 4 is made of, for example, an organic material including a pigment or a dye that selectively transmits wavelengths corresponding to colors of G (green), B (blue), and R (red). The first unit microlens 5a is made of a transparent resin having a refractive index of about 1.4 or more and 1.7 or less, for example.

  When the path followed by the light incident on the solid-state imaging device 10 is classified, (a) light collected by the first unit microlens 5a and reaching the photoelectric conversion region 1a, (b) the photoelectric conversion region 1a of the adjacent pixel. (C) light absorbed by the color filter 4 of the adjacent pixel, (d) light absorbed by the wiring layer 2, and (e) the surface of the first unit microlens 5a or the solid-state imaging device 10 Reflected light from

  In order to increase the light receiving sensitivity, it is necessary to increase the light (A) and reduce the light (B) to (E) that becomes a loss. In particular, light (b) is not preferable because light from adjacent pixels (crosstalk light) leaks, leading to deterioration in color purity and generation of noise. Crosstalk light is likely to occur when the chief ray is incident on the solid-state imaging device 10 at an angle.

  The microlens of the microlens group 5 constituting the solid-state imaging device 10 of the present invention is composed of either a first unit microlens 5a made of a convex lens or a second unit microlens 5b made of a Fresnel lens. The first unit microlens 5a and the second unit microlens 5b have N1 as the number of pixels in which the first unit microlens 5a is formed in the unit region S in the plane of the solid-state imaging device 10, and the second unit microlens 5b. When the number of pixels on which the unit microlenses 5b are formed is N2, the distance r measured from the center position of the solid-state image sensor is long from the center where the distance r measured from the center position of the solid-state image sensor 10 is relatively short. The ratio N1 / N2 monotonously decreases toward the periphery. In this case, the center position of the solid-state imaging device is the center between the upper end of the uppermost photoelectric conversion region and the lower end of the lowermost photoelectric conversion region, and the left end of the leftmost photoelectric conversion region and the rightmost photoelectric conversion region. Refers to the center of the right edge.

FIG. 2 schematically shows the difference in the light propagation path between the first unit microlens 5a and the second unit microlens 5b when the principal ray is incident on the solid-state imaging device 10 at an angle. is there. FIG. 2A shows the case of the first unit microlens 5a, and FIG. 2B shows the case of the second unit microlens.

  In the case where the first unit microlens 5a has a convex lens shape as shown in FIG. 2A, the inclined light incident near the top of the first unit microlens 5a is photoelectrically converted with the top of the first unit microlens 5a. Since the distance to the region 1a is long, the light is condensed on a region outside the photoelectric conversion region 1a, crosstalk light to the adjacent pixels is increased, and light receiving sensitivity is lowered.

  When the second unit microlens 5b shown in FIG. 2B is formed, since the distance between the top of the second unit microlens 5b and the photoelectric conversion region 1a is short, the inclined light is condensed inside the photoelectric conversion region 1a. In addition, crosstalk light to adjacent pixels is reduced, and light receiving sensitivity is increased.

  As shown in FIG. 3A, light passing through the center of the aperture stop of the camera optical system (solid line) is referred to as a principal ray, and light rays passing through a peripheral part off the center (broken line) are referred to as peripheral rays. A principal ray is irradiated perpendicularly to the center O of the solid-state imaging device 10, and a conical peripheral ray is incident with the principal ray as an axis. As shown in (b), the chief ray is inclined with respect to the peripheral portion E where the distance r measured from the center position of the solid-state imaging device 10 is large, and a conical peripheral ray having the chief ray as an axis is incident. For this reason, light that is greatly inclined with respect to the vertical direction of the solid-state imaging device 10 is incident on the peripheral portion E, and the light receiving sensitivity is likely to decrease. When the sensitivity of the peripheral pixels is lowered, shading occurs in which the peripheral image having a large distance measured from the center position of the captured image becomes dark, which causes deterioration in image quality.

  In order to suppress the occurrence of such shading, when the arrangement number of the first unit microlenses 5a in the unit region is N1, and the arrangement number of the second unit microlenses 5b is N2, the ratio N1 / N2 is solid. The distance r measured from the center position of the solid-state image sensor from the central portion where the distance r measured from the center position of the solid-state image sensor is small so that the numerical value decreases as the distance r measured from the center position of the image sensor increases. The microlens 5a and the microlens 5b are arranged so as to monotonously decrease toward the periphery. In such a configuration, the sensitivity of the peripheral portion where the distance r measured from the center position of the solid-state imaging device 10 is large can be improved as compared with the conventional configuration.

  The peripheral portion in this case includes not only the position in contact with the periphery composed of the upper, lower, left and right ends but also the position close to the periphery and having a large distance r measured from the center position of the solid-state imaging device.

  4A is a plan view of the substantially rectangular solid-state imaging device 10, and FIGS. 4B and 4C are cross-sectional views taken along a straight line Q. FIG. As for the arrangement of the microlens group 5 and the photoelectric conversion element 1a, as shown in FIG. 4B, the center position of the first unit microlens 5a and the second unit microlens 5b of the microlens 5 for each pixel and the photoelectrical element. The center positions of the conversion elements 1a may coincide with each other, and as shown in FIG. 4C, the center positions of the first unit microlens 5a and the second unit microlens 5b of the microlens 5 toward the periphery. The center position of each pixel of the photoelectric conversion element 1a may be shifted in the horizontal direction. By shifting the center position of each pixel, the light whose chief ray is inclined can easily enter the photoelectric conversion element 1a.

  The center position of the solid-state imaging device 10, that is, the center between the upper end of the uppermost photoelectric conversion region and the lower end of the lowermost photoelectric conversion region, the left end of the leftmost photoelectric conversion region and the right end of the rightmost photoelectric conversion region Is a center position O, a periphery E consisting of upper, lower, left and right edges of the substantially rectangular solid-state imaging device 10, and a perpendicular drawn from the center position O toward the periphery E is a perpendicular Q.

  Here, an arrangement method of the first unit microlens 5a and the second unit microlens 5b will be described. First, a rectangular unit area S having a certain unit area is set, and a position where the center position O is included in the unit area S is set as a start position. Then, the unit area S is moved toward any one of the peripheral areas E of the substantially rectangular solid-state imaging device 10 while shifting the pixel area by one pixel, and the movement is ended when one side of the unit area S reaches the periphery E.

  At this time, the distance r measured from the center position of the solid-state imaging device 10 to the center position of the unit region S increases as the center O moves from the periphery E to the first unit microlens 5a included in the unit region S. The first unit microlens 5a and the second unit microlens 5b are arranged on the solid-state imaging element 10 so that the ratio N1 / N2 of the number of arrangement of the second unit microlenses 5b decreases monotonously.

  In this case, the center position of the unit area S is the center between the upper end of the area and the lower end of the area, and represents the position between the left end of the area and the center of the right end of the area.

  FIG. 4 is an example when the number of pixels included in the unit region S is 9 (3 vertical pixels × 3 horizontal pixels). The monotonic decrease here includes a case where the ratio N1 / N2 is unchanged when the unit region S is shifted by one pixel. However, the ratio N1 / N2 at the end of movement of the unit area S is set to be smaller than the ratio N1 / N2 at the start of movement of the unit area S. The number of pixels in the unit area S may be a square such as 16 pixels (4 × 4) or 25 pixels (5 × 5) in addition to the 9 pixels described above, and may be 6 pixels (2 × 3) or 12 pixels (3 × 4). It is good also as rectangles, such as.

  In the vicinity of the center position O of the solid-state imaging device 10, the chief ray is incident substantially perpendicularly, so that the light condensing property can be improved by arranging more first unit microlenses 5 a in the unit region S. Then, as the proximity to the periphery E of the solid-state imaging device 10, the principal ray comes to be incident with an inclination, so that the second unit microlenses 5 b are arranged more in the unit region S. As described above, the ratio of the first unit microlens 5a and the second unit microlens 5b is increased as the unit region S moves from the central part of the solid-state imaging device 10 toward the peripheral part where the distance r measured from the central position increases. Is arranged so as to monotonously decrease, the sensitivity of both the vicinity of the center position O and the vicinity of the periphery E of the solid-state imaging device 10 can be increased.

  As the first unit microlens 5a, for example, a convex lens made of a part of a substantially spherical surface can be used to effectively increase the light receiving sensitivity. In addition to the spherical surface, it is desirable to select an appropriate shape according to the pixel structure, such as an ellipsoid or a part of a paraboloid. By adopting a Fresnel lens as the second unit microlens 5b, the light with the principal ray inclined can be effectively condensed in the photoelectric conversion region 1a, and the sensitivity can be increased. The Fresnel lens employed here is a Fresnel lens made of a relief type diffractive lens having a structure in which a convex lens is cut out in a ring shape and the height is uniform as shown in FIG. 5A, or as shown in FIG. 5B. It may be a Fresnel lens composed of a binary diffraction lens approximated by a step-shaped cross section.

  When the distance between the center of the pixel of interest and the center position O of the solid-state imaging device 10 is r, only the first unit microlens 5a is arranged in a region satisfying r <R (R is a certain value). In the region satisfying = 0 and satisfying r ≧ R, only the second unit microlens 5b may be arranged, and the microlens group 5 may be arranged so as to satisfy N1 = 0.

  The distance R is, for example, the distance between the center position of the pixel where the chief ray tilt angle is 10 ° and the center position O of the solid-state imaging device 10. This is because the sensitivity of the Fresnel lens is easier to improve than the convex lens when the chief ray tilt angle is 10 ° or more.

At least one of the first unit microlens 5a and the second unit microlens 5b may have an elliptical bottom shape when viewed vertically from the light incident side of the solid-state imaging device 10. This is effective in improving the sensitivity to, for example, a rectangle when the dimensions of the pixel or the photoelectric conversion region 1a are different when measured in the horizontal direction or the vertical direction of the solid-state imaging device 10. In such a case, if the shape of the bottom surface of the first unit microlens 5a or the second unit microlens 5b is circular, a gap is generated between the pixels, and light transmitted through the gap is lost. .

  When the center position of the first unit microlens 5a or the second unit microlens 5b and the center position of the photoelectric conversion region are shifted in the horizontal direction, assuming that the shift amount is Δ, the center position O of the solid-state image sensor 10 and the pixel The shift amount may be determined as described by the function Δ (r) of the center position distance r. When Δ is described as a function of the distance r, the shading that appears in the image captured by the camera equipped with the solid-state image sensor 10 has a circular shape with the center position O of the solid-state image sensor 10 as a reference. There is a merit that shading correction by is easy. On the other hand, when the shift amount Δ is not described as a function of the distance r, for example, asymmetric and complex shading occurs, and it is difficult to correct the shading by calculation.

  Such a microlens group 5 can be manufactured by utilizing photolithography. A photo resist having a pattern corresponding to the microlens is used to expose and develop the photosensitive resist applied on the substrate, thereby producing a three-dimensional rectangular pattern. The resist is exposed and developed using a mask whose light transmittance changes stepwise to obtain a three-dimensional resist pattern. Further, if necessary, the pattern of the microlens is transferred to the base material by etching the resist together with the base material.

  Next, the operation of the solid-state imaging device 10 of the present embodiment having such a configuration will be described. The light L incident on the solid-state imaging device 10 is collected by the first unit microlens 5 a or the second unit microlens 5 b and enters the color filter 4. The color filter 4 transmits light having a necessary wavelength according to the pixel and absorbs light having an unnecessary wavelength. The transmitted light is incident on the wiring layer 2. In the case of the solid-state imaging device 10 without the color filter 4, the incident light is collected by the microlens 5 and then directly enters the wiring layer 2.

  Part or all of the light transmitted through the wiring layer 2 is collected on the photoelectric conversion region 1a. When the photoelectric conversion region 1a is irradiated with light, a charge is generated in proportion to the light intensity, and the generated charge is transferred to an electronic circuit to read a signal.

  A unit region S includes a first unit microlens 5a made of a convex lens in the central portion of the solid-state image pickup device 10 in a plan view, and a second unit microlens 5b made of a Fresnel lens in the periphery of the solid-state image pickup device 10 in a plan view. More are placed inside. Thereby, the light inclined in the peripheral part where the distance r measured from the center position of the solid-state image sensor 10 is large is efficiently condensed on the photoelectric conversion region 1a, and the center where the distance r measured from the center position of the solid-state image sensor 10 is small. It is possible to suppress a decrease in the light receiving sensitivity of the peripheral portion having a large distance r measured from the center position with respect to the portion.

  The solid-state imaging device 10 according to this embodiment can be applied to electronic devices typified by, for example, digital cameras, video cameras, camera-equipped mobile phones, and the like, so that the sensitivity and image quality uniformity of these electronic devices can be improved. .

  An embodiment of the solid-state imaging device 10 of the present invention will be described.

(Example 1 and Comparative Example 1)
The simulation of the light receiving sensitivity when the first unit microlens 5a is a convex lens made up of a part of a spherical surface and the second unit microlens 5b is a Fresnel lens is performed in increments of 5 ° from 0 ° to 30 °. did. The simulation was performed by strict coupled wave theory (RCWA method). The case where the first unit microlens 5a is periodically arranged on one surface of the solid-state imaging device 10 and the case where the second unit microlens 5b is periodically arranged on one surface on the solid-state imaging device 10 are divided. And simulated. In the simulation, the incident power to one pixel is set to 1 [W], and the incident light amount [W] to the photoelectric conversion region 1a is calculated as the light receiving sensitivity. The width of the photoelectric conversion region 1a is the same as the pixel pitch. The simulation model is shown in FIG. A wiring layer 2 made of Al of a material having a width of 1.2 μm was formed in a boundary region with an adjacent pixel.

<Calculation conditions>
Pixel pitch: 5 μm
Height of the first unit microlens 5a: 2.5 μm
Height of second unit microlens 5b: 0.92 μm
Refractive index of the microlens group 5: 1.6
Without color filter Wiring layer thickness: 6μm
Incident wavelength: 0.55 μm
The second unit microlens 5b was a relief type diffractive lens having a sawtooth cross section with a height of 0.92 μm. The height of the second unit microlens 5b was calculated from λ / (n−1). Here, λ is the wavelength, n is the refractive index of the microlens group 5, and the height is set so that the diffraction efficiency of the relief type diffractive lens is theoretically optimal.

  Table 1 (Comparative Example 1) shows the light receiving sensitivity when the first unit microlens 5a is a convex lens made of a part of a spherical surface, and Table 1 shows the light receiving sensitivity when the second unit microlens 5b is a Fresnel lens (implemented). Example 1). FIG. 7 is a graph in which the angle is plotted on the horizontal axis and the intensity of incident light on the light receiving surface is plotted on the vertical axis. As a result, when the incident angle is less than 10 °, the light receiving sensitivity of the first unit microlens 5a is strong, whereas when the incident angle is 10 ° or more, the light receiving sensitivity of the second unit microlens 5b is strong. Was confirmed.

(Example 2 and Comparative Example 2)
The pixel pitch was changed to 10 μm, and a simulation was similarly performed under the calculation conditions shown below.

<Calculation conditions>
Pixel pitch: 10 μm
Height of the first unit microlens 5a: 5 μm
Height of second unit microlens 5b: 0.92 μm
Microlens group 5 refractive index: 1.6
Wiring layer thickness: 6μm
Incident wavelength: 0.55 μm
Table 2 (Comparative Example 2) shows the case where the first unit microlens 5a is a convex lens made of a part of a spherical surface, and Table 2 (Example 2) shows the case where the second unit microlens 5b is a Fresnel lens. . Further, FIG. 8 is a graph in which the angle is plotted on the horizontal axis and the intensity of incident light on the light receiving surface is plotted on the vertical axis. As a result, when the incident angle is less than 10 °, the light receiving sensitivity of the first unit microlens 5a is strong, whereas when the incident angle is 10 ° or more, the light receiving sensitivity of the second unit microlens 5b is strong. Was confirmed.

From the above examples, it was confirmed that when the chief ray is vertical, the microlens is a convex lens, that is, the first unit microlens 5a has an effect of improving the light receiving sensitivity.
Further, it was confirmed that when the chief ray is tilted, the sensitivity is improved by using a microlens as a Fresnel lens, that is, the second unit microlens 5b.

  In other words, a microlens that is a convex lens, that is, a first lens is formed in a central portion in plan view of the solid-state imaging device 10 where incident light is incident vertically, that is, a portion having a small distance r measured from the center position of the solid-state imaging device. A large number of unit microlenses 5a may be arranged. In addition, a microlens made of a Fresnel lens, ie, a second lens, is mainly provided in a peripheral portion in plan view of the solid-state imaging device 10 where incident light is inclined and incident, that is, a portion where the distance r measured from the center position of the solid-state imaging device is large. It can be said that more unit microlenses 5b should be arranged. Furthermore, the incident light to the solid-state image sensor 10 is incident with a stepwise inclination from the central part toward the peripheral part as the distance r measured from the center position of the solid-state image sensor increases. Accordingly, as the distance r measured from the center position of the solid-state imaging device is increased in accordance with the incident angle, that is, from the central portion toward the peripheral portion, the first unit microlens 5a formed of a convex lens in the unit region S. It can be seen that it is sufficient to monotonously increase the second unit microlens 5b made of a Fresnel lens while monotonously decreasing the number of arrangement.

  As described above, it is possible to suppress a decrease in light receiving sensitivity in the peripheral portion where the distance r measured from the center position with respect to the central portion where the distance r measured from the center position of the solid-state imaging device 10 is small.

DESCRIPTION OF SYMBOLS 1 ... Substrate 1a ... Photoelectric conversion area 2 ... Wiring layer 3 ... Wiring 4 ... Color filter 5 ... Micro lens group 5a ... First unit micro lens 5b ... Second unit microlens 10 ... Solid-state imaging device O ... Center position E ... Peripheral S ... Unit area

Claims (5)

A solid-state imaging device having a photoelectric conversion region divided for each pixel, and a microlens group composed of unit microlenses corresponding to the pixels on a one-to-one basis,
The microlens group includes a first unit microlens made of a convex lens and a second unit microlens made of a Fresnel lens,
A first unit that is the number of first unit microlenses included in the unit region when a plurality of unit regions having the same rectangular shape including a plurality of unit microlenses are arbitrarily set in the microlens group. The arrangement number ratio N1 / N2 between the arrangement number N1 of microlenses and the arrangement number N2 of second unit microlenses, which is the number of the second unit microlenses included in the unit region, is the solid-state imaging element. A solid-state imaging device characterized in that the numerical value decreases as the distance r measured from the center position increases.   The first unit microlens is arranged in a region where the chief ray tilt angle of light incident on the solid-state imaging device is less than 10 °, and the second unit microlens is placed in a region where the chief ray tilt angle is 10 ° or more. The solid-state imaging device according to claim 1, wherein:   At least one of the first unit microlens and the second unit microlens is characterized in that the shape of the bottom surface when viewed vertically from the light incident side of the solid-state imaging device is an ellipse, The solid-state imaging device according to claim 1 or 2.   At least one of the first unit microlens and the second unit microlens has a difference between the center position of the photoelectric conversion region divided for each pixel and the center position of the corresponding unit microlens. 4. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is represented by a difference function Δ (r) that is a function of a distance r measured from a center position of the solid-state imaging device.   An electronic apparatus comprising the solid-state imaging device according to claim 1.

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