JP2017011091A - Solid-state image pickup device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress sensitivity deterioration at a peripheral portion as compared with sensitivity deterioration at a center portion in a solid-state image pickup element such as CCD, CMOS sensor or the ike on which microlenses are uniformly laid.SOLUTION: In a solid-state image pickup element 10 including a photoelectric conversion area 1a, color filters 4 which are provided on the light incident side of the photoelectric conversion area and transmit therethrough light of a predetermined wavelength for each pixel, and convex microlenses 5 which are provided on the light incidence side of the color filters 4 and formed in one-to-one correspondence with the color filters, the microlenses comprise two types of microlenses 5 which are different in radius of curvature, and the ratio between the arrangement numbers of the two types of microlenses, the arrangement number of the first microlenses 5a having a small radius of curvature and the arrangement number of the second microlenses 5b having a large radius of curvature is monotonously reduced from the center portion to the peripheral portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid-state image pickup device in which a minute microlens is provided on a light-receiving element, and relates to a solid-state image pickup device that can suppress a decrease in sensitivity in a peripheral portion with respect to a central portion, and an electronic apparatus including the solid-state image pickup device.

  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 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 the microlenses optimized under the condition that the chief ray is vertical are spread uniformly, even if the sensitivity is sufficiently high in the central part of the sensor, there is a problem that the sensitivity is insufficient in the peripheral part. .

JP 2000-332226 A

  The present invention has been made in view of the above problems, and suppresses a decrease in sensitivity of a peripheral portion with respect to a central portion of a solid-state imaging device such as a CCD or a CMOS sensor in which microlenses are uniformly spread. Objective.

As means for solving the above problems, the first aspect of the present invention includes a photoelectric conversion region,
A color filter that is provided on the light incident side of the photoelectric conversion region and transmits light of a predetermined wavelength for each pixel, and a convex shape that is provided on the light incident side of the color filter and has a one-to-one correspondence with the color filter A solid-state imaging device having a microlens group of microlenses,
The microlens group includes a first microlens having a top radius of curvature R1 and a second microlens having a top radius of curvature R2, satisfying R1 <R2, and the unit area of the microlens group The solid-state imaging device is characterized in that the ratio N1 / N2 between the number N1 of the first microlens and the number N2 of the second microlens decreases monotonously from the central portion toward the peripheral portion.

The cross section of the first microlens may be a part of a substantially parabola, and the cross section of the second microlens may be a part of a substantially ellipse.

  Further, when the height of the microlens is H and the pitch of the pixels is P, H / P is 0.25 or more and 0.65 or less.

  Further, R1 / P and R2 / P, which are ratios between the radius of curvature R1 of the first microlens and the radius of curvature R2 of the second microlens and the pitch P, are both 0.4 or more and 2 or less. It is characterized by being.

  In addition, a fine uneven shape having a height of 50 nm or less is formed on the surface of the microlens.

  In addition, an electronic apparatus including the solid-state imaging device according to the first aspect.

  According to the present invention, it is possible to suppress a decrease in sensitivity of the peripheral portion with respect to the central portion of the microlens group, to improve the light receiving sensitivity, and it has been found that the sensitivity improvement is particularly effective when the chief ray is inclined. .

1 is a schematic cross-sectional view illustrating an example of a solid-state imaging device including a microlens according to an embodiment of the present invention. It is the number plane and sectional drawing which showed the example of arrangement | positioning of the micro lens in embodiment of this invention. In the solid-state imaging device of the embodiment of the present invention, the light propagation path difference due to the difference in the radius of curvature of the top of the microlens is shown, and the light due to the difference in the curvature of the top of the microlens when the chief ray is tilted It is a schematic cross-sectional view showing the difference in the propagation path. 1 is a schematic plan view and a schematic cross-sectional view of a substantially rectangular solid-state imaging device in an embodiment of the present invention. In the solid-state image sensor of the embodiment of the present invention, it is a graph of the light receiving sensitivity when light is irradiated to the solid-state image sensor tilted from the 0 ° direction. In the solid-state image sensor of the embodiment of the present invention, it is a graph of light receiving sensitivity when light is irradiated with tilting from the direction of 20 ° to the solid-state image sensor.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1A is a plan view showing an example of a solid-state imaging device 10 having a microlens, and FIG. 1B is a cross-sectional view taken in the thickness direction from a broken line V shown in FIG.

  In FIG. 1, 1 is a substrate, 1a is a photoelectric conversion region, 2 is a light shielding film, 3a is a first planarizing layer, 4 is a color filter, 3b is a second planarizing layer, and 5 is a microlens.

  P represents the pitch of the microlenses 5 and H represents the height at the apex T of the microlenses 5. Here, the height H is a height when the surface 3b 'on the light incident surface side of the second planarizing layer 3b is used as a reference. When the second planarizing layer 3b is not formed, the height is based on the surface 4 'on the light incident surface side of the color filter 4 as a reference.

  Further, the height H of the microlens 5 is a sum (H = H0 + H1) of the thickness H0 of the valley portion of the microlens 5 and the height H1 of the curved lens portion.

  The light incident on the solid-state imaging device 10 is refracted by the microlens 5 and further passes through the color filter 3, and light corresponding to the color of each pixel is condensed on the photoelectric conversion region 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. In order to prevent color mixture between the pixels, the light shielding film 2 is formed of a metal such as aluminum, silver, chromium, tungsten, or the like as necessary. The planarization layer 3 is formed of silicon oxide, silicon nitride, or the like.

  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 microlens 5 is made of, for example, a transparent resin having a refractive index of about 1.4 or more and 1.7 or less. The microlens 5 has a convex lens shape for condensing incident light on the photoelectric conversion region 1a.

  FIG. 2 is a diagram illustrating an arrangement example of the microlenses 5. FIG. 2A shows a case where the bottom surface of the microlens 5 is circular and arranged with no gap between pixels. In the arrangement example shown in FIG. 2A, when the pixel is cut in the width direction V, the adjacent microlenses 5 overlap each other, so that the valleys of the microlenses 5 have a thickness H0.

  FIG. 2B shows a case where the bottom surface of the microlens 5 is rectangular and arranged with no gap between pixels. In the arrangement example of FIG. 2B, when the pixel is cut in the width direction V, the adjacent microlenses 5 do not overlap with each other, and therefore the valley thickness H0 of the microlenses 5 is not formed.

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

  In order to increase the light receiving sensitivity, it is necessary to increase the light (A) and reduce the light (B) to (D) 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 5 constituting the solid-state imaging device 10 of the present invention is configured by one of a first microlens 5a having a top radius of curvature R1 and a second microlens 5b having a top radius of curvature R2. .

  The first microlens 5a and the second microlens 5b satisfy R1 <R2, and the number of pixels in which the first microlens 5a is formed in the unit region S in the plane of the solid-state imaging device 10 is N1. When the number of pixels on which the second microlenses 5b are formed is N2, the ratio N1 / N2 monotonously decreases from the central part to the peripheral part of the solid-state imaging device 10. The reason why this configuration is adopted is described below.

  FIG. 3 schematically shows the difference in the propagation path of light due to the difference in the curvature of the top of the microlens 5 when the chief ray is incident on the solid-state image sensor 10. FIG. 3A shows a case where the curvature of the top of the microlens 5 is small, and FIG. 3B shows a case where the curvature of the top of the microlens 5 is large.

When the curvature of the top of the microlens 5 is small as shown in FIG. 3A, the inclined light incident on the microlens enters the solid-state imaging device 10 without being refracted, so that crosstalk light to adjacent pixels increases. As a result, the light receiving sensitivity decreases.

  On the other hand, if the curvature of the top of the microlens 5 is reduced, the light condensing property of the principal ray incident perpendicularly to the solid-state imaging device 10 can be enhanced, and the light receiving sensitivity can be effectively increased. Hereinafter, a microlens having a small curvature at the top as shown in FIG. 3A is referred to as a first microlens 5a.

  In addition, when the curvature of the top of the microlens 5 is large as shown in FIG. 3B, the inclined light incident on the microlens 5 is easily refracted in the direction of the photoelectric conversion region 1a. Therefore, crosstalk light to adjacent pixels can be suppressed as compared with the case where the top curvature is small, and the light receiving sensitivity is increased. Hereinafter, a microlens having a large curvature at the top as shown in FIG. 3B is referred to as a second microlens 5b.

  The radius of curvature of the microlens 5 can be obtained from the following formula 1.

R (x) in Equation 1 is the radius of curvature of the microlens 5 at the coordinate x. Here, x is a distance measured in the horizontal direction from the apex T of the microlens 5 as shown in FIG. 1B, and h (x) is at a position x away from the apex T of the microlens 5 in the horizontal direction. This is the height of the microlens 5.

  Since R1 and R2 are the radii of curvature at the top of the microlens 5, they are obtained by calculating R (x) at x = P / 2 in Equation 1.

  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 in FIG. 4A. As for the arrangement of the microlens 5 and the photoelectric conversion element 1a, as shown in FIG. 4B, the center position of the microlens 5 and the center position of the color filter 4 for each pixel may be matched. ), The center positions of the pixels of the microlens 5 and the color filter 4 may be shifted in the horizontal direction toward the periphery. By shifting the center position of each pixel, the light whose chief ray is inclined can easily enter the photoelectric conversion element 1a.

  4A, the center of the solid-state imaging device 10 is O, the peripheral portion of the solid-state imaging device 10 is E, and the perpendicular drawn from the center O toward the peripheral portion E is Q. The peripheral portion E represents one of the sides of the substantially rectangular solid-state imaging device 10.

  Here, an arrangement method of the first microlens 5a and the second microlens 5b will be described. First, a rectangular unit region S having a certain unit area is set, and a position where the center O is included in the unit region S is set as a start position. Then, the unit region S is moved toward the peripheral portion E while shifting one pixel at a time, and the movement is terminated when one side of the unit region S reaches the peripheral portion E.

  At this time, the ratio N1 / N2 of the number N1 of the first microlenses 5a and the number N2 of the second microlenses 5b included in the unit region S monotonously decreases as the center O moves from the peripheral portion E to the peripheral portion E. The first microlens 5 a and the second microlens 5 b are arranged on the solid-state imaging device 10.

  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 O of the solid-state imaging device 10, the chief ray is incident substantially perpendicularly. Can be increased. On the other hand, since the principal ray is inclined and enters as it approaches the peripheral portion E of the solid-state imaging device 10, the second microlens 5b that easily refracts the inclined light in the direction of the photoelectric conversion region 1a is provided in the unit region S. Place more.

  As described above, the number N1 of the first microlenses 5a and the number N2 of the second microlenses 5b are monotonically decreased as the unit region S moves from the central portion to the peripheral portion of the solid-state imaging device 10. By arranging so, the sensitivity of both the vicinity of the center O and the vicinity of the peripheral portion E of the solid-state imaging device 10 can be increased.

  When the first microlens 5a is a lens whose cross section is substantially a parabola, for example, and the second microlens 5b is a lens whose cross section is a part of a substantially ellipse, for example, the light receiving sensitivity is improved. Can be enhanced.

  A lens having a cross section that is substantially a parabola has a smaller radius of curvature at the top than a lens having a cross section that is a part of a substantially ellipse, so that a desired effect can be expected (details are described in the examples). Here, the parabolic shape and the elliptical shape mean those in which the height h (x) of the microlens 5 is expressed by the following equations 2 and 3, respectively.

In Equations 2 and 3, H0 and H1 are arbitrary constants. The ratio H / P of the height H (H = H0 + H1) at the apex of the microlens 5 and the pitch P of the microlens 5 is preferably set to be 0.25 or more, and H / P is It is particularly preferable to set it to be 0.25 or more and 0.65 or less.

  When H / P is out of the above range, the light condensing property of the microlens 5 is deteriorated, and the light receiving sensitivity is greatly reduced. Details are described in the Examples.

  Here, “substantially” of “substantially parabola” and “substantially oval” means that an error within ± 50 nm is allowed with respect to the height H described in Equations 2 and 3. This is because, if the error of the height H is within this range, the adverse effect on the light collecting property due to the scattering of visible light can be ignored.

  The surface of the microlens 5 may be intentionally provided with a fine uneven shape having an amplitude within ± 50 nm. By providing a fine concavo-convex shape with an amplitude smaller than the wavelength, the refractive index change felt by the light on the surface of the microlens 5 becomes moderate, and the Fresnel loss on the lens surface can be reduced.

  Such a microlens 5 can be manufactured by utilizing photolithography. As a method using optical lithography, a method using heat flow and a method using a gray scale mask are known.

In the former method, a three-dimensional rectangular pattern is produced by exposing and developing a photosensitive resist coated on a substrate using a photomask on which a pattern corresponding to a microlens is formed. Thereafter, the microlens is formed by deforming the resist into a curved shape by heat flow. Further, if necessary, the pattern of the microlens is transferred to the base material by etching the resist together with the base material.

  In the latter method, a resist is exposed and developed using a mask whose light transmittance changes stepwise to obtain a three-dimensional resist pattern. Furthermore, the microlens pattern of a base material is produced by transferring a resist pattern to a base material as needed.

  Next, the operation of the solid-state imaging device 10 of this embodiment having such a configuration will be described. The light L incident on the solid-state image sensor 10 is collected by the microlens 5 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 light that has passed through the color filter 4 passes through the planarization layer 3 and is condensed 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 first microlens 5a having a small curvature radius at the top is provided at the center of the solid-state image sensor 10 in a plan view, and a second microlens 5b having a large curvature radius at the top is provided at a periphery in the plan view of the solid-state image sensor 10. More units are arranged in the unit area S. Thereby, the fall of the light reception sensitivity of the peripheral part with respect to the center part of the solid-state image sensor 10 can be suppressed.

  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.

  The simulation of the light receiving sensitivity was performed when the cross section of the microlens 5 was composed of (a) a part of a parabola, (b) a part of an ellipse, (c) a triangle, and (d) a Sin curve. When the height H is the same, the curvature radius R is in the order of part of ellipse> part of parabola> Sin curve> triangle. The microlenses 5 have a substantially circular bottom surface, and are arranged in the pixels without gaps as shown in FIG. The simulation was performed using a time-domain difference method (FDTD method) generally used in optical analysis of wavelength order structures.

<Calculation conditions>
Pixel pitch: 1.2 μm
Microlens 5 height: 0.2 μm to 0.8 μm, in increments of 0.05 μm Microlens 5 refractive index: 1.5
Color filter 4: 0.7 μm thickness, RGB three-color Bayer arrangement Light-shielding film 2: None First planarization layer 3 a: SiO ₂ layer (0.5 μm)
Second planarizing layer 3b: None Incident wavelength: 0.55 μm
Incident angle: 0 °, 20 °
Polarization: TE wave, TM wave Light receiving surface: set at the interface between the planarization layer 3 and the photoelectric conversion region 1a (the light receiving surface is set to the same size as the pixel area)
Table 1 shows the heights H [μm] and H0 [μ when the cross section of the microlens 5 is part of a parabola.
m], the radius of curvature R [μm] at the top of H1 [μm], and the radius of curvature R / P normalized by the pitch P are shown.

Table 2 also shows the specifications of the radius of curvature R [μm] and the pitch P at the top at heights H [μm], H0 [μm], and H1 [μm] when the cross section of the microlens 5 is part of an ellipse. The converted radius of curvature R / P is shown.

Further, Table 3 shows heights H [μm], H0 [μm], and H1 [μm] when the cross section of the microlens 5 is a triangle. Since the cross-sectional shape is a triangle, the radius of curvature R is not shown in Table 3.

  Table 4 shows the curvature radii normalized by the top radius of curvature R [μm] and the pitch P at heights H [μm], H0 [μm], and H1 [μm] when the cross section of the microlens 5 is a Sin curve. R / P is noted.

The results of calculating the light receiving sensitivity of the G pixel when the incident light is incident at 0 ° (incident perpendicular to the solid-state imaging device 10) according to the height of the microlens 5 shown in Tables 1 to 4 are shown in Table 5 and FIG. As shown in FIG. That is, Table 5 and FIG. 5 show the calculation results of the light receiving sensitivity when the cross section of the microlens is a parabola, an ellipse, a triangle, and a Sin curve.

  Here, the light receiving sensitivity represents the total power (average of TE and TM) of light incident on the photoelectric conversion surface 1a when light of 1 power is incident on the G pixel (reflection on the photoelectric conversion surface 1a is taken into consideration). Not)

In addition, Table 6 and FIG. 6 show the results of light receiving sensitivity when incident light is incident at 20 °.

From Table 5 and FIG. 5, the maximum sensitivity was obtained at 0 ° incidence when the cross section of the microlens 5 was a parabola and the height was 350 nm. Moreover, it turns out that it is preferable that the cross section of the microlens 5 is a parabola, and the ratio H / P of the height H and the pitch P is set to 0.25 or more. In particular, the ratio H / P of the height H to the pitch P is more preferably set to 0.25 or more and 0.65 or less. By setting the ratio H / P within the above range, it is possible to suppress the sensitivity reduction due to the deterioration of the light condensing property of the microlens 5 within 3% from the maximum sensitivity.

  On the other hand, from Table 6 and FIG. 6, the maximum sensitivity at 20 ° incidence was obtained when the cross section of the microlens 5 was part of an ellipse and the height was 550 nm. Moreover, it is preferable that the cross section of the micro lens 5 is a part of an ellipse, and the ratio H / P of the height H to the pitch P is set to 0.25 or more.

  In particular, the ratio H / P between the height H and the pitch P is more preferably set to 0.25 or more and 0.65 or less. By setting the ratio H / P within the above range, it is possible to suppress the sensitivity reduction due to the deterioration of the light condensing property of the microlens 5 within 3% from the maximum sensitivity.

From Tables 1 and 2 and the above-described results, it is preferable that the ratio R / P of the radius of curvature R and the pitch of the microlens 5 is set to 0.4 or more and 2 or less. For example, when R / P is 0.4, according to Table 1, when the cross section of the microlens 5 is a parabola, the height H is 0.75 [μm].

  Here, when R / P is smaller than 0.4, the height of the microlens 5 is further increased, and the deterioration of the light collecting property becomes remarkable. When R / P is 2, from Table 2, when the cross section of the microlens 5 is a part of an ellipse, the height H is 0.3 [μm]. When R / P is larger than 2, the height of the microlens 5 is further lowered, and the deterioration of the light collecting property becomes remarkable.

  Therefore, it is preferable that R / P is defined to be not less than 0.4 and not more than 2 as a range in which the microlens 5 whose section is a part of a parabola or an ellipse does not lose the focusing power.

  From Tables 5 and 6 and FIGS. 5 and 6, it can be seen that when the cross-sectional shape of the microlens is triangular, the light receiving sensitivity is lower than that of the parabola and the elliptical shape regardless of the height of the microlens. When the cross-sectional shape is a triangle, since the cross-sectional shape of the side surface is a straight line, the light condensing property is weak, and there is a lot of light scattered on the photoelectric conversion element 1a of the adjacent pixel or absorbed and absorbed by the adjacent color filter. It is thought to be.

  Further, when the cross-sectional shape is a Sin curve, when the height is 400 nm or more, the ratio R / P of the radius of curvature to the pitch becomes as small as 0.3 or less, so that it is effective on the photoelectric conversion element 1a as described above. It can be confirmed that the light cannot be collected and the sensitivity is lowered.

  From the above examples, it was confirmed that when the cross-sectional shape of the microlens 5 is part of a parabola when the chief ray is vertical, the light receiving sensitivity is most effectively improved. Moreover, it was confirmed that the cross-sectional shape is a part of an ellipse, so that it is most effective in improving sensitivity when the chief ray is tilted.

  In other words, if a large number of microlenses 5 whose cross-sectional shape is a part of a parabola (having a small curvature radius at the top) are arranged in the central portion in plan view of the solid-state imaging device 10 where incident light is incident vertically. Good. In addition, more microlenses 5 whose cross-sectional shape is a part of an ellipse (having a large radius of curvature at the top) are arranged in the periphery of the solid-state imaging device 10 where incident light is incident with an inclination. I can say that.

  Furthermore, the incident angle of the light incident on the solid-state image sensor 10 is gradually inclined from the vertical as it goes from the central part to the peripheral part of the solid-state image sensor 10. Therefore, the number of arranged micro lenses in the unit region S monotonously decreases as the number of arranged micro lenses with a small radius of curvature increases from the central part to the peripheral part of the solid-state imaging device 10 in accordance with the incident angle of the principal ray. In addition, it can be seen that the number N2 of microlenses having a large curvature radius may be monotonously increased.

  As described above, it is possible to suppress a decrease in the light receiving sensitivity of the peripheral portion with respect to the central portion of the solid-state imaging element 10.

DESCRIPTION OF SYMBOLS 1 ... Substrate 1a ... Photoelectric conversion area | region 2 ... Light-shielding film 3 ... Planarization layer 3a ... 1st planarization layer 3b ... 2nd planarization layer 3b '... Surface 4 on the light incident surface side of the second planarizing layer ... Color filter 4 '... Surface 5 on the light incident surface side of the color filter ... Micro lens 5a ... First micro lens 5b .... Second microlens 10 ... Solid-state imaging device

Claims (6)

A photoelectric conversion region;
A color filter that is provided on the light incident side of the photoelectric conversion region and transmits light of a predetermined wavelength for each pixel;
A solid-state imaging device having a microlens group including convex microlenses provided on the light incident side of the color filter and corresponding to the color filter on a one-to-one basis,
The microlens group includes a first microlens having a top radius of curvature R1 and a second microlens having a top radius of curvature R2.
R1 <R2 is satisfied,
The ratio N1 / N2 of the number N1 of the first microlenses in the unit region of the microlens group and the number N2 of the second microlens is increased from the center to the periphery of the microlens group. A solid-state image pickup device that monotonously decreases.   2. The solid-state imaging according to claim 1, wherein a cross section of the first microlens is substantially part of a parabola, and a cross section of the second microlens is substantially part of an ellipse. element.   3. The solid-state imaging according to claim 1, wherein H / P is not less than 0.25 and not more than 0.65, where H is the height of the microlens and P is the pitch of the pixels. element.   R1 / P and R2 / P, which are ratios of the radius of curvature R1 of the first microlens and the radius of curvature R2 of the second microlens and the pitch P, are both 0.4 or more and 2 or less. The solid-state imaging device according to claim 1, wherein   5. The solid-state imaging device according to claim 1, wherein a fine uneven shape having a height of 50 nm or less is formed on a surface of the microlens.   An electronic apparatus comprising the solid-state imaging device according to claim 1.