JP2009094339A - Solid-state image sensor and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging device which prevents shading and an imaging apparatus using such a solid-state image sensor. <P>SOLUTION: The solid-state imaging device at least includes a plurality of light receiving parts disposed two dimensionally at a predetermined pitch and a microlens array in which a plurality of microlenses are disposed two dimensionally corresponding to the respective light receiving parts. The microlenses composing the microlens arrey include 2 kinds or more microlenses in which an inclination angle of the basal face of the microlens against a plane parallel to the light receiving face is different. An effective imaging area is divided into a plurality of partial areas from the center toward the circumference, and the microlenses having the same inclination angle are disposed in each partial area. At a border part where the partial areas having different inclination angles of the basal face of the microlenses abut, a middle belt part is established where the microlenses having respective inclination angles of the neighboring partial areas are present in a mixture, and the difference in the inclination angles of the neighboring microlenses is kept by ≤10°. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and an imaging device, and more particularly, to a solid-state imaging device in which a plurality of light receiving units and minute condensing lenses (microlenses) are arranged, and an imaging device using the solid-state imaging device.

In recent years, digital cameras and video cameras that capture still images and moving images have become widespread in various fields. These cameras use solid-state image sensors such as CCDs and CMOSs. However, with the advancement of semiconductor technology, the pixels of the solid-state image sensors have been further miniaturized, and the cameras themselves have been downsized. In such a solid-state imaging device, a microlens for increasing the amount of light incident on the light receiving portion and improving the sensitivity is provided corresponding to the light receiving portion of each pixel.
Here, the solid-state imaging device has a phenomenon called shading in which the sensitivity decreases around the effective imaging region. In this shading, as shown in FIG. 13, the light incident from the camera lens is incident substantially perpendicularly at the center of the effective imaging area, whereas the incident angle increases toward the periphery of the effective imaging area, and the effective imaging area This is a phenomenon caused by a decrease in the amount of incident light on the light receiving unit 51 at the periphery.

Conventionally, in order to prevent shading, in consideration of the chief ray incident angle from the camera lens, the microlens 52 is arranged at the position of the light receiving unit 51 at the center of the effective imaging region, and light is received at the periphery of the effective imaging region. The micro lenses 52 are arranged so as to be shifted from the positions of the portions 51 (see FIG. 14). For example, the arrangement pitch of the microlenses is set slightly smaller than the arrangement pitch of the light receiving portions by arranging the microlenses by performing microscaling from the center of the effective imaging region toward the peripheral portion. (Patent Document 1). As a result, there is no deviation between the position of the light receiving unit and the microlens at the center of the effective imaging area, but the position of the microlens gradually shifts toward the center of the effective imaging area with respect to the corresponding position of the light receiving unit as it moves toward the periphery It becomes. It has also been proposed to correct shading by providing a refracting portion under the microlens and gradually increasing the inclination angle of the refracting portion from the center of the effective imaging region toward the peripheral portion. (Patent Document 2).
JP-A-6-140609 JP 2004-144841 A

As miniaturization of digital cameras, video cameras, etc. progresses, the camera lens optical system also becomes smaller and thinner, and the camera lens is arranged close to the solid-state image sensor, so the effective imaging area of the solid-state image sensor In the peripheral area, the incident angle of the chief ray incident from the camera lens becomes larger and more precise shading correction is required.
For example, consider shading correction by a method of changing the tilt angle of the microlens described above. When manufacturing a microlens having a refracting portion by a photolithography method using a photomask having a gradation expression in which a dot pattern having a size less than the resolution limit of an exposure apparatus is arranged on the mask Assuming that the number of dots expressed on the region of 20 × 20, the photomask to be used has 20 × 20 dots (FIG. 15) for forming a microlens and a desired inclination in the refracting portion. 20 × 20 dots (FIG. 16) for giving The portion corresponding to the highest portion of the refracted portion is the rightmost dot row (row indicated by an arrow in the figure) among the 20 × 20 dots in FIG. However, when the gradation expression of the inclination angle is performed with the 20 dots at the right end, the light transmittance of the photomask is in the range of 0/20 to 20/20, and only about 20 gradations can be expressed. Therefore, for example, when 320 pixels are arranged from the center to the periphery of the effective imaging area and the maximum inclination angle required for the refracting portion is 40 °, 40 ° needs to be expressed in 320 steps on average. In the above example, only about 20 gradations can be expressed.

Further, if 320 gradations are to be expressed by the rightmost dot row in FIG. 16, it is necessary to arrange 320 × 320 dots in one pixel. However, for example, when the pixel size is 2 μm × 2 μm, one pixel size is 10 μm × 10 μm on the pentaploid photomask, and if one side is divided into 320 dots, the size of one dot is about 30 nm. Therefore, it is difficult to manufacture with the current photomask manufacturing technique.
On the other hand, shading correction can also be performed by changing the inclination of the microlens stepwise. For example, assume a case where the shading shown in FIG. 18 caused by the camera lens characteristics shown in FIG. 17 is corrected. In this case, as shown in FIG. 19, corresponding to the chief ray incident angle in FIG. 1, the effective imaging region is divided into a plurality of regions to set partial regions (six in the drawing), and steps are made between these partial regions. Therefore, the inclination angle of the microlens is changed. However, there is always a boundary line between the partial areas where microlenses with different inclination angles exist (parts where the light collection efficiency changes stepwise). There is a problem in that adjacent portions are continuous, which causes linear sensitivity unevenness and greatly impairs product quality.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid-state imaging device that prevents shading and an imaging apparatus that uses such a solid-state imaging device.

In order to achieve such an object, a solid-state imaging device according to the present invention includes a plurality of light receiving units arranged two-dimensionally at a predetermined pitch, and a plurality of microlenses arranged two-dimensionally corresponding to each of the light receiving units. In the solid-state imaging device including at least the microlens array, the microlens constituting the microlens array includes two or more types of microlenses having different inclination angles of the bottom surface of the microlens with respect to a plane parallel to the light receiving surface. The effective imaging area is divided into a plurality of partial areas from the center toward the periphery, and microlenses having the same inclination angle are arranged in each partial area, and partial areas having different inclination angles on the bottom surface of the microlens are adjacent to each other. In the boundary portion, there is an intermediate band portion in which microlenses having respective inclination angles in adjacent partial regions are present, and adjacent The difference in inclination angle of Kurorenzu is a such that 10 ° or less configuration.
As another aspect of the present invention, the mixing ratio of the microlenses having different inclination angles in the intermediate strip portion is continuously changed within a range of 1: 0 to 0: 1.

  The solid-state imaging device according to the present invention includes a plurality of light receiving units arranged two-dimensionally at a predetermined pitch, and a micro lens array formed by two-dimensionally arranging a plurality of micro lenses corresponding to each of the light receiving units. At least in the solid-state imaging device provided, the microlens constituting the microlens array is composed of two or more types of microlenses having different inclination angles of the bottom surface of the microlens with respect to the plane parallel to the light receiving surface, and the effective imaging area is from the center Divided into a plurality of partial areas toward the periphery, there are partial areas in which microlenses with different inclination angles are mixed, and the difference in inclination angle between adjacent microlenses is 10 It was set as the following.

As another aspect of the present invention, the mixing ratio of the microlenses having different inclination angles in the partial region is changed along the direction from the center of the effective imaging region to the periphery in the partial region. did.
As another aspect of the present invention, the configuration is such that the mixing ratio of the microlenses having different inclination angles in the partial area is substantially uniform in the partial area.
As another aspect of the present invention, the microlenses having different inclination angles are randomly arranged in the partial region.
In another aspect of the present invention, the average inclination angle of the microlens tends to increase from the center of the effective imaging region toward the periphery.
As another aspect of the present invention, the partial region has a mosaic shape.
As another aspect of the present invention, the partial area is configured to be a concentric annular area centered on the center of the effective imaging area.
The imaging apparatus of the present invention is configured to include the above-described solid-state imaging device.

Such a solid-state imaging device of the present invention can perform an optimal microlens tilt arrangement suitable for lens characteristics such as the relationship between the chief ray incident angle of the camera lens and the image height, and can perform precise shading correction. In addition, since the difference in tilt angle between adjacent microlenses is 10 ° or less, the sensitivity variation is small, and a pentaploid mask can be produced by electron beam drawing. The complicated operation of individually designing the microlenses for the entire region is not necessary, and an effect is achieved that precise shading correction can be easily performed.
The image pickup apparatus of the present invention is of high quality with low loss of vignetting and the like due to oblique incidence within the effective image pickup area, and with a low efficiency distribution with respect to the amount of incident light. Thinning is possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Solid-state imaging device]
FIG. 1 is a schematic configuration diagram showing an example of a solid-state imaging device of the present invention. In FIG. 1, a solid-state imaging device 1 is opposed to a substrate 2 via a substrate 2 having a plurality of light receiving portions 3 and a light shielding film 4 provided at a constant arrangement pitch, and a passivation layer 5 having a light shielding layer 6. The lower planarization layer 7, the color filter 8, the upper planarization layer 9, and the microlens array 10 are stacked. The microlens array 10 includes a plurality of microlenses 11 that are two-dimensionally arranged so as to correspond to the individual light receiving units 3. And with respect to the several light-receiving part 3 provided with the fixed arrangement | positioning pitch, the microlens 11 which comprises the microlens array 10 differs in the inclination angle of the microlens bottom face with respect to a surface parallel to the surface which the light-receiving part 3 makes. It consists of two or more types of microlenses. In addition, the solid-state image sensor of this invention is not limited to the structure shown in FIG.

  Here, the inclination angle of the bottom surface of the microlens will be described. FIG. 2 is a view showing the microlens 11 formed on the upper planarizing layer 9. In FIG. 2, the upper surface of the upper planarizing layer 9 is a surface parallel to the surface formed by the light receiving unit 3, and the bottom surface 11 a of the microlens 11 is not inclined in the central region of the effective imaging region. 9 is 0 ° with respect to the upper surface 9a. Further, the microlens 11 positioned in the peripheral direction is disposed on the wedge-shaped base 12 having the inclined surface 12a inclined at an angle θ with respect to the upper surface 9a of the upper planarizing layer 9 and facing the peripheral direction of the effective imaging region. Has been. Therefore, the bottom surface 11 a of the microlens 11 forms an inclination angle θ with the top surface 9 a of the upper planarizing layer 9. The inclination angle θ changes with a tendency to increase from the center of the effective imaging region toward the peripheral direction.

  Formation of such a microlens having a desired inclination angle can be performed as follows, for example. First, a photosensitive resin layer whose remaining film thickness changes according to the exposure amount is formed on the upper planarizing layer 9. This photo-resin layer is a photomask that controls the transmitted light amount (exposure amount) distribution when exposed by the fine dot pattern distribution that cannot be resolved at the exposure wavelength, and is produced according to the shape of the wedge-shaped base to be formed The wedge-shaped base 12 having a desired inclination angle is formed by exposing and developing using the photomask formed. Next, the microlens 11 is formed on the wedge-shaped base 12 using a photosensitive resin material for microlenses.

  Moreover, the microlens 11 and the wedge-shaped base 12 can be formed simultaneously. For example, in order to produce a tilted microlens that integrates the wedge-shaped base shown in FIG. 2 and the microlens thereon, the height distribution, the exposure amount of the microlens resist to be used, and the remaining film thickness From the above relationship, the transmittance distribution of a mask that represents one tilted microlens is obtained, and the tilted microlens is formed by expressing the transmittance distribution with an arrangement of several tens of dots × several tens of dot patterns per pixel. It can form by exposing using a mask. As the mask pattern, for example, a mask pattern for forming a microlens as shown in FIG. 15 and a mask pattern for forming a wedge-shaped base as shown in FIG. 16 are added.

The solid-state imaging device 1 according to the present invention divides an effective imaging region into a plurality of partial regions from the center toward the periphery, and microlenses having the same inclination angle are arranged in each partial region, and the inclination angle of the bottom surface of the microlens An intermediate band portion in which microlenses having respective inclination angles in the adjacent partial regions are mixed is provided at the boundary portion where the partial regions different from each other are adjacent to each other. Further, the difference in inclination angle between adjacent microlenses is set to 10 ° or less. If this difference in tilt angle exceeds 10 °, the sensitivity difference between pixels exceeds about 5%, which is not preferable because the sensitivity variation increases.
The above-described solid-state imaging device of the present invention will be described by taking as an example the case of correcting the shading shown in FIG. 18 caused by the camera lens characteristics as shown in FIG. In this case, as shown in FIG. 3, the X-axis direction from the center of the effective imaging region is divided into six partial regions (1) to (6), and each partial region is represented by a solid line in FIG. 3. Inside, microlenses having the same inclination angle are arranged. Then, an intermediate band portion in which microlenses having respective inclination angles in the adjacent partial regions are mixed is provided at the boundary portion where the partial regions are adjacent.
The size of the partial region can be set as appropriate. For example, the width can be set in a range of 100 to 10,000 μm, or the number of pixels in the width direction can be set in a range of 50 to 2,000. Can do.

For example, when the mixing ratio of the microlenses having different inclination angles in the intermediate band portion is 1: 1, the intermediate inclination angle between adjacent partial regions is set as shown by a solid line in FIG. A state in which the microlens is provided appears in the intermediate band portion. As a result, the step-like changes in the six partial areas are subdivided, and it is possible to prevent the light receiving portions having slightly different sensitivities from being formed on the boundary lines between the partial areas, thereby preventing defects such as linear sensitivity unevenness. can do.
Further, when the mixing ratio of the microlenses having different inclination angles in the intermediate band portion is continuously changed, that is, from 1: 0 to 0: 1, as shown by a chain line in FIG. The change in the tilt angle can be made smoother.
The width of the intermediate strip portion can be set as appropriate. For example, it can be set in the range of 1 to 50% of the width of the partial region, or in the range of 20 to 5,000 μm.
In the solid-state imaging device 1 of the present invention, the effective imaging region is divided into a plurality of partial regions from the center toward the periphery, and microlenses having different inclination angles are mixed in the plurality of partial regions. In this case, the difference between the inclination angles of adjacent microlenses is set to 10 ° or less. If this difference in tilt angle exceeds 10 °, the sensitivity difference between pixels exceeds about 5%, which is not preferable because the sensitivity variation increases.

  Such a solid-state imaging device of the present invention will be described by taking as an example the case of correcting the shading shown in FIG. 18 caused by the camera lens characteristics as shown in FIG. In this case, as shown in FIG. 4, the X-axis direction from the center of the effective imaging area is divided into six partial areas (1) to (6). In the partial region (1), two types of microlenses having inclination angles of 0 ° and 5 ° are mixed and arranged. That is, the ratio of microlenses with an inclination angle of 0 ° is set to 100% on the left side of the partial area (1) (the center side of the effective imaging area), and the mixing ratio of microlenses with an inclination angle of 5 ° toward the right side (peripheral direction). Two types of microlenses are randomly arranged while gradually increasing the ratio of the microlenses having an inclination angle of 5 ° in the partial region (1). Hereinafter, in the partial region (2), two types of microlenses with inclination angles of 5 ° and 9.7 °, and in the partial region (3), two types of microlenses with inclination angles of 9.7 ° and 14.5 °. In the lens and partial region (4), two types of microlenses with inclination angles of 14.5 ° and 18.4 °, and in the partial region (5), two types of micro lenses with inclination angles of 18.4 ° and 20 °. In the lens and partial area (6), two types of microlenses having inclination angles of 20 ° and 19.6 ° are mixed and arranged in the same manner as in the partial area (1).

  This makes it possible to change the tilt angle corresponding to the camera lens characteristics of FIG. 17 almost continuously, that is, to change the average tilt angle of the microlens nonlinearly. In the present invention, the average inclination angle is an average value of inclination angles of the bottom surface of the microlens in a set of adjacent pixels including the pixel when attention is paid to a certain pixel.

Next, the solid-state imaging device of the present invention will be described with reference to embodiments.
(First embodiment)
FIG. 5 is a diagram for explaining the arrangement of microlenses in an embodiment of the solid-state imaging device of the present invention. The solid-state imaging device of the present embodiment divides the effective imaging area into a plurality of partial areas from the center toward the periphery, and microlenses having the same inclination angle are arranged in each partial area, and the inclination angle of the bottom surface of the microlens In the boundary part where adjacent partial areas are adjacent to each other, an intermediate belt-like part in which microlenses having respective inclination angles in the adjacent partial areas are mixed is provided, and the difference in inclination angle between adjacent microlenses is 10 ° or less. It is what.

  In the example shown in FIG. 5, a solid-state image sensor with a horizontally long (horizontal: vertical = 16: 9) screen having a pixel size of 2 μm × 2 μm and a pixel number of 1920 × 1080 is assumed, and gradually increases in the X-axis direction. The shading correction in the X-axis direction is performed by changing the inclination angle of the bottom surface of the microlens. As shown in FIG. 5, in the microlens array composed of a plurality of microlenses, the effective imaging area is (1) to (5), (2 ′) to (1) to (5) in the X-axis direction from the center (0, 0). It is divided into nine partial areas (5 ′). The partial area (1) includes the center (0, 0) of the effective imaging area, the inclination angle of the bottom surface of the microlens is 0 °, and the partial area (2) located outside thereof is the inclination of the bottom surface of the microlens. The angle is 5 °, the region (2 ′) has a microlens bottom surface tilt angle of 5 °, the partial region (3) located outside thereof has a microlens bottom surface tilt angle of 10 °, and the region (3 ′) is The inclination angle of the bottom surface of the microlens is 10 °, the partial region (4) located outside thereof has an inclination angle of the bottom surface of the microlens of 15 °, and the region (4 ′) has an inclination angle of the bottom surface of the microlens of 15 °. In the partial area (5) located outside, the inclination angle of the bottom surface of the microlens is 20 °, and in the area (5 ′), the inclination angle of the bottom surface of the microlens is 20 °.

  In addition, intermediate band portions as indicated by chain lines are set in adjacent partial regions, and micro lenses having respective inclination angles in the adjacent partial regions are mixed in these intermediate band portions. For example, in an intermediate region between the partial region (2) and the partial region (3), microlenses with an inclination angle of 5 ° and microlenses with an inclination angle of 10 ° are mixed. This mixture ratio can be set to 1: 1, for example, and the mixture ratio of two types of microlenses with different inclination angles may be continuously changed within a range of 1: 0 to 0: 1. For example, microlenses with an inclination angle of 5 ° are mixed in a ratio of 2/3 and microlenses with an inclination angle of 10 ° are mixed at a ratio of 1/3 on the partial area (2) side, and the inclination angle is on the partial area (3) side. The boundary between the partial area (2) and the partial area (3) is changed continuously so that microlenses with 5 ° are mixed at a ratio of 1/3 and microlenses with an inclination angle of 10 ° are 2/3. Smooth inclination angle change in the vicinity of the part becomes possible. Furthermore, the ratio of microlenses with an inclination angle of 5 ° is set to approximately 100% on the partial area (2) side, and the ratio of microlenses with an inclination angle of 10 ° is increased toward the partial area (3), and the partial area (3 ) Side, microlenses with an inclination angle of 10 ° are mixed so as to be almost 100%, thereby further changing the inclination angle of the microlens near the boundary between the partial area (2) and the partial area (3). It will be smooth. Similarly to the above, the intermediate belt portion between the other partial regions can be mixed with micro lenses having two kinds of inclination angles.

(Second Embodiment)
In the first embodiment described above, the effective imaging region is divided into a plurality of partial regions in the X-axis direction, and shading correction is performed by gradually changing the tilt angle of the bottom surface of the microlens in the X direction. It is also possible to perform shading correction by dividing the region into a plurality of partial regions over all 360 ° directions. FIG. 6 is a view showing such an embodiment, where the partial area A is a circular area including the center of the effective imaging area, and the arranged microlenses have a bottom surface tilt angle of 0 °. . On the outside, 12 partial areas B1 to B12 are provided via an annular intermediate strip (hatched area), and every 30 ° (15 °, 45 °, Center direction of effective imaging area parallel to lines (indicated by alternate long and short dash lines) extending radially at 75 °, 105 °, 135 °, 165 °, 195 °, 225 °, 255 °, 285 °, 285 °, 315 °, 345 °) A microlens whose bottom surface is inclined by 5 ° is arranged for each partial region. Further, an intermediate belt-shaped portion (a hatched region) is also provided between the partial regions B1 to B12. Twelve partial areas C1 to C12 are provided outside these partial areas B1 to B12 via a ring-shaped intermediate strip (hatched area), and every 30 ° from the center of the effective imaging area. In parallel with the radially extending line (indicated by the alternate long and short dash line), a microlens whose bottom surface is inclined by 10 ° in the central direction of the effective imaging region is arranged for each partial region. In addition, an intermediate band (a hatched area) is also provided between the partial areas C1 to C12. Twelve partial areas D1 to D12 are provided outside these partial areas C1 to C12 via an annular intermediate strip (hatched area), and every 30 ° from the center of the effective imaging area. A microlens whose bottom surface is inclined by 15 ° in the direction of the center of the effective imaging region is arranged for each partial region in parallel with a radially extending line (indicated by a one-dot chain line). Since a solid-state image sensor with a horizontally long (horizontal: vertical = 16: 9) screen is assumed, there are no four partial regions D3, D4, D9, and D10. In addition, an intermediate band (a hatched area) is also provided between the partial areas D1 to D12. Further, twelve partial areas E1 to E12 are provided outside these partial areas D1 to D12 via a ring-shaped intermediate strip (hatched area), 30 from the center of the effective imaging area. A microlens whose bottom surface is inclined by 20 ° in the central direction of the effective imaging region is arranged for each partial region in parallel with a line (indicated by a one-dot chain line) that extends radially every angle. Again, since a solid-state image sensor with a horizontally long (horizontal: vertical = 16: 9) screen is assumed, there are no eight partial regions E2 to E5 and E8 to E11. In addition, an intermediate band (a hatched area) is also provided between the partial areas E1 to E12.

  Then, in the intermediate band portion set between the adjacent partial areas, microlenses having respective inclination angles in the adjacent partial areas are mixedly arranged. FIG. 7 is an enlarged view of partial regions B6, B7, C6, and C7 surrounded by a chain line circle in FIG. 6, and an intermediate band portion set between adjacent partial regions is indicated by hatching. In the middle band portion at the boundary between the partial area B6 and the partial area B7 in FIG. 7, a microlens (B6) whose bottom surface is inclined by 5 ° in the central direction of the effective imaging region in parallel with a line extending at 165 °, and 195 ° And a microlens (B7) whose bottom surface is inclined by 5 ° in the central direction of the effective imaging region in parallel with the line extending in the direction. The mixing ratio of such two types of microlenses can be set to 1: 1 such that the microlenses (B6) and the microlenses (C6) are alternated, for example. Further, the mixing ratio of the two types of microlenses may be continuously changed within a range of 1: 0 to 0: 1. For example, the microlens (B6) is mixed at a ratio of 2/3 and the microlens (B7) at a ratio of 1/3 on the partial area B6 side of the intermediate band-shaped portion, and the microlens (B6) is 1/3 on the partial area B7 side. By continuously changing the microlenses (B7) so as to be mixed at a ratio of 2/3, it is possible to smoothly change the inclination angle in the vicinity of the boundary between the partial region B6 and the partial region B7. Further, the ratio of the microlens (B6) is set to approximately 100% on the partial area B6 side of the intermediate band-shaped portion, and the ratio of the microlens (B7) is increased toward the partial area B7, and the microlens (B7) is increased on the partial area B7 side. Are mixed so as to be almost 100%, the change in the inclination angle of the microlens near the boundary between the partial region B6 and the partial region B7 becomes smoother.

  Similarly, in the middle band-like portion at the boundary between the partial area C6 and the partial area C7, a microlens (C6) whose bottom surface is inclined by 10 ° in the central direction of the effective imaging region in parallel with a line extending at 165 ° and at 195 ° A microlens (C7) whose bottom surface is inclined by 10 ° in the center direction of the effective imaging region is disposed in parallel with the extending line. On the other hand, in the middle band-like portion at the boundary between the partial region B6 and the partial region C6, a microlens (B6) whose bottom surface is inclined by 5 ° in the central direction of the effective imaging region in parallel with a line extending at 165 ° is also at 165 °. A microlens (C6) whose bottom surface is inclined by 10 ° in the center direction of the effective imaging region is disposed in parallel with the extending line. In addition, an intermediate band-like portion at the boundary between the partial region B7 and the partial region C7 has a microlens (B7) whose bottom surface is inclined by 5 ° in the central direction of the effective imaging region in parallel with a line extending to 195 °, and also at 195 °. A microlens (C7) whose bottom surface is inclined by 10 ° in the center direction of the effective imaging region is disposed in parallel with the extending line. The mixing ratio of the two types of microlenses in these intermediate strips can be the same as that of the above-described intermediate strips.

  In addition, as for the portion where the intermediate band-shaped portions intersect, for example, as shown in FIG. 8A, the boundary of the adjacent intermediate band-shaped portions can be provided obliquely toward the intersection center. As shown in B), all types of microlenses arranged in the four partial regions B6, B7, C6, and C7 adjacent to the intersecting portion (hatched portion) may be mixed and arranged. In this case, the mixture ratio may be arranged so that the inclination angle gradually increases toward the center direction of the effective imaging region (the direction of arrow a in FIG. 8B). It may be arranged at random, and the mixing ratio at the intersecting portions may be equalized.

(Third embodiment)
In the solid-state imaging device according to the present embodiment, the effective imaging region is divided into a plurality of partial regions from the center toward the periphery, and the plurality of partial regions are portions where microlenses having different inclination angles are mixed. It is assumed that there is a region, and the difference in inclination angle between adjacent microlenses is 10 ° or less.
FIG. 9 is a layout diagram of microlenses of the solid-state imaging device of the present embodiment. In FIG. 9, the (0, 0) point indicates the center point of the effective imaging area, and in order to avoid the complexity of the drawing, only 30 × 20 pixels in the ¼ area in the upper right corner from the center point. Is shown. In the solid-state imaging device shown in FIG. 9, (X1) to (X6) are divided into six in the X-axis direction, and one partial region is composed of 5 × 20 pixels. In addition, the microlens has a microlens bottom tilt angle of 0 ° (indicated in white in the figure) and a microlens base tilted by 5 ° in the direction of the zero point of the X axis (indicated by a hatched line in the figure). It is composed of two types. The existence probability of microlenses with an inclination angle of 5 ° changes by 20% from 0% to 100% every 5 pixels toward the peripheral direction of the X axis, and the arrangement of microlenses at 20 pixels in the Y axis direction is as follows. It is uniform. That is, in the partial area (X1), all the five microlenses in the X-axis direction have an inclination angle of 0 ° (the existence probability of microlenses having an inclination angle of 5 ° is 0%), and in the partial area (X2), X One microlens with an inclination angle of 5 ° out of the five in the axial direction (existence probability 20%), and two microlenses with an inclination angle of 5 ° out of the five in the X-axis direction in the partial region (X3). (Existence probability 40%) In the partial region (X4), among the five in the X-axis direction, three microlenses with an inclination angle of 5 ° (existence probability 60%), and in the partial region (X5), the X-axis Of the five directions, there are four microlenses with an inclination angle of 5 ° (existence probability 80%), and within the partial region (X6), all five microlenses with an inclination angle of 5 ° (existence probability 100%). ).

In this example, the change is stepwise by 20%, but an actual solid-state imaging device has an array of at least several hundred pixels × several hundred pixels. For example, if there is an array of 600 pixels in the X-axis direction and one partial area is set with 5 × 20 100 pixels in the same manner as described above, every 5 pixels (each partial area) in the X-axis direction. If microlenses with an inclination angle of 5 ° are added one by one, the existence probability of microlenses with an inclination angle of 5 ° changes by 2%, and can be changed almost continuously.
The above-described embodiments are examples, and the solid-state imaging device of the present invention is not limited to these.

[Imaging device]
FIG. 10 is a schematic cross-sectional view showing an embodiment of the imaging apparatus of the present invention. In FIG. 10, an imaging device 31 of the present invention includes a substrate 33 including the solid-state imaging device 32 of the present invention, a sealing member 34 disposed outside the solid-state imaging device 32, and the sealing member 34. And a protective material 35 disposed to face the solid-state imaging device 32 with a desired gap. The solid-state imaging device 32 is connected to an external terminal 38 via a wiring 36 and front and back conductive vias 37. Such a ceramic package type image pickup device 31 can be used for various digital cameras, video cameras, and the like, and the sensitivity, size and thickness of the camera can be reduced.

FIG. 11 is a schematic cross-sectional view showing another embodiment of the imaging apparatus of the present invention. An imaging device 41 of the present invention shown in FIG. 11 is an example of a camera module for a mobile phone, and includes a substrate 43 provided with the solid-state image sensor 42 of the present invention and a sealing member disposed outside the solid-state image sensor 42. 44, an infrared cut filter 45 disposed so as to face the solid-state imaging device 42 with a desired gap, a lens barrel 46 disposed on the infrared cut filter 45, and the inside of the lens barrel 46 The lens unit 47 attached to the lens is provided. Such an image pickup apparatus 41 can be reduced in size and thickness because the solid-state image pickup element 42 of the present invention is subjected to shading correction and has high sensitivity.
The image pickup apparatus of the present invention is not limited to the above-described embodiment, and any structure that includes the solid-state image pickup element of the present invention as a solid-state image pickup element may be used, and the configurations of various conventional image pickup apparatuses may be employed as they are. it can.

Next, an Example is shown and this invention is demonstrated further in detail.
[Example]
First, a wafer on which a CMOS image sensor having a pixel light receiving portion pitch of 2.0 μm and a pixel number of 1920 × 1080 was formed.
Next, a lower planarization layer, a color filter, an upper planarization layer, and a microlens were formed on the wafer as described below.
(Formation of lower planarization layer)
After cleaning the wafer surface with a spin scraper, a photo-curing acrylic transparent resin material (CT-2020L manufactured by Fuji Microelectronics Materials Co., Ltd.) is spin-coated, and then pre-baking, UV exposure and post-baking are performed. A lower planarizing layer (thickness 0.3 μm) was formed.

(Formation of color filter)
The following materials were prepared as negative photosensitive red materials (R materials), green materials (G materials), and blue materials (B materials).
Material for R: SR-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for G: SG-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for B: SB-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
In the order of formation of G, R, and B, the above materials are spin-coated, and an RGB color filter (thickness 0.8 μm) is formed by performing pre-baking, exposure with a 1/5 reduction type i-line stepper, development, and post-baking. did. As a developing solution, a 50% diluted solution of CD-2000 manufactured by Fuji Microelectronic Materials Co., Ltd. was used. The arrangement pitch of the color filters was 2 μm.
(Formation of upper planarization layer)
A light curable acrylic transparent resin material (CT-2020L manufactured by Fuji Microelectronics Materials Co., Ltd.) is spin-coated on the RGB color filter, followed by pre-baking, ultraviolet exposure and post-baking, and an upper flattening layer (Thickness 0.3 μm) was formed.

(Formation of microlenses)
On top flattening layer, spin coating of MFR401L made by JSR Co., Ltd. as microlens material, pre-baking, exposure with 1/5 reduction type i-line stepper, development, post-exposure, post-baking, Formed. A 1.19% solution of TMAH (tetramethylammonium hydroxide) was used as the developer.
In the exposure described above, the method for forming the wedge-shaped base and the microlens at the same time as described in the above embodiment is used, and the mask pattern for forming the microlens as shown in FIG. 15 and the wedge-shaped base as shown in FIG. It exposed using the mask pattern which considered the mask pattern for formation.

  Thus, in the partial areas (1) to (5) and (2 ′) to (5 ′) as shown in FIG. 5, microlenses having an inclination angle of 0 ° were arranged in the partial area (1). In addition, four types of microlenses having inclination angles of 5 °, 10 °, 15 °, and 20 ° were arranged in the order of (2) to (5). Similarly, four types of microlenses having inclination angles of 5 °, 10 °, 15 °, and 20 ° were arranged in the order of (2 ′) to (5 ′). Note that the inclinations are all directed toward the periphery of the effective imaging area. Further, in the intermediate belt-shaped portion, the microlenses having different inclination angles are arranged so that the mixing ratio is 1: 1. In this case, the partial area (1) is on the X axis from the effective imaging area center to 102 pixels, and the partial areas (2) and (2 ') are from 103 pixels to 311 pixels on the X axis, and the partial area (3) , (3 ′) is from 312 pixels to 563 pixels on the X axis, partial areas (4) and (4 ′) are from 564 pixels to 878 pixels on the X axis, and partial areas (5) and (5 ′) are From 879 pixels on the X axis to 960 pixels on the outermost periphery. The intermediate strips between the partial areas are (1) and (2), (2) and (3), (3) and (4), (4) and (5), and (1 ') and (2 '), (2') and (3 '), (3') and (4 '), (4') and 25 pixels on both sides from the boundary line of the partial region, respectively, 50 pixels in total And the width.

Next, the bonding pad portion was opened. That is, a positive resist (i-line positive resist PFI-27 manufactured by Sumitomo Chemical Co., Ltd.) is spin-coated, and after pre-baking, exposure and development are performed using a photomask having a pattern corresponding to the bonding pad portion and the scribe portion. Then, the resist in the bonding pad portion and the scribe portion was removed, and then oxygen ashing was performed, and the upper planarization layer and the lower planarization layer on the portion were removed by etching. Next, the positive resist was removed using a resist stripping solution.
Next, the wafer was diced and package assembled to produce the solid-state imaging device of the present invention.

[Comparative example]
A solid-state imaging device was fabricated in the same manner as in the example except that the microlens was formed as follows.
(Formation of microlenses)
On top flattening layer, spin coating of MFR401L made by JSR Co., Ltd. as microlens material, pre-baking, exposure with 1/5 reduction type i-line stepper, development, post-exposure, post-baking, Formed. A 1.19% solution of TMAH (tetramethylammonium hydroxide) was used as the developer.
In the exposure described above, exposure was performed using a mask pattern for forming a microlens as shown in FIG.

[Evaluation]
For the solid-state imaging device manufactured as described above, the sensitivity was measured under the following conditions, and the results are shown in FIG. As shown in FIG. 12, the solid-state image sensor of the present invention is effectively subjected to shading correction, and the sensitivity distribution (shown by a solid line in FIG. 12) is the sensitivity distribution (solid line in FIG. 12) of the solid-state image sensor of the comparative example. It was confirmed that the improvement was about 20% compared to (shown).
(Sensitivity measurement conditions)
For the produced solid-state imaging device, a camera lens having the characteristics shown in FIG.
The sensitivity distribution in the X-axis direction with respect to the white light source was measured.

  The present invention can be applied to various fields in which a small and highly reliable solid-state imaging device and imaging device are required.

It is a schematic block diagram which shows an example of the solid-state image sensor of this invention. It is a figure for demonstrating the inclination-angle of a micro lens. It is a figure which shows the inclination-angle of the micro lens for every partial area for demonstrating the solid-state image sensor of this invention. It is a figure which shows the inclination-angle of the micro lens for demonstrating the solid-state image sensor of this invention. It is a figure for demonstrating arrangement | positioning of the micro lens in one Embodiment of the solid-state image sensor of this invention. It is a figure for demonstrating arrangement | positioning of the micro lens in other embodiment of the solid-state image sensor of this invention. FIG. 7 is an enlarged view of a partial region surrounded by a circle in FIG. 6. It is a figure for demonstrating arrangement | positioning of the micro lens in the cross | intersection part of the intermediate | middle strip | belt-shaped part shown by FIG. It is a figure for demonstrating arrangement | positioning of the micro lens in other embodiment of the solid-state image sensor of this invention. It is a figure for demonstrating an example of the imaging device of this invention. It is a figure for demonstrating the other example of the imaging device of this invention. It is a figure which shows the result of the sensitivity measurement in an Example. It is a figure for demonstrating the shading phenomenon in a solid-state image sensor. It is a figure for demonstrating correction | amendment of the shading in a solid-state image sensor. It is a figure for demonstrating the photomask for microlenses. It is a figure for demonstrating the photomask for microlenses. It is the figure which showed the relationship between the chief ray incident angle of a lens used for an imaging device, and image height. It is a figure which shows the sensitivity difference by the shading within an effective imaging area. It is a figure which shows correction | amendment of the inclination-angle of the micro lens for shading correction | amendment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor 2 ... Board | substrate 3 ... Light-receiving part 4 ... Light-shielding film 5 ... Passivation layer 6 ... Light-shielding layer 7 ... Lower planarization layer 8 ... Color filter 9 ... Upper planarization layer 10 ... Micro lens array 11 ... Micro lens 11a Microlens bottom surface 12 ... Wedge-shaped base 31, 41 ... Imaging device 32, 42 ... Solid-state imaging device

Claims (10)

In a solid-state imaging device comprising at least a plurality of light receiving portions arranged two-dimensionally at a predetermined pitch, and a microlens array in which a plurality of microlenses are two-dimensionally arranged corresponding to the respective light receiving portions,
The microlens constituting the microlens array is composed of two or more kinds of microlenses having different inclination angles of the bottom surface of the microlens with respect to the plane parallel to the light receiving surface, and the effective imaging area is divided into a plurality of partial areas from the center toward the periphery. Microlenses having the same inclination angle are arranged in the individual partial areas, and the microlenses having respective inclination angles in the adjacent partial areas are adjacent to the boundary area where the partial areas having different inclination angles on the bottom surface of the microlens are adjacent to each other. A solid-state imaging device characterized in that there is an intermediate belt-like portion in which a mixture of two or more microlenses and a difference in inclination angle between adjacent microlenses is 10 ° or less.   2. The solid-state imaging device according to claim 1, wherein a mixture ratio of microlenses having different inclination angles in the intermediate band portion continuously changes within a range of 1: 0 to 0: 1. In a solid-state imaging device comprising at least a plurality of light receiving portions arranged two-dimensionally at a predetermined pitch, and a microlens array in which a plurality of microlenses are two-dimensionally arranged corresponding to the respective light receiving portions,
The microlens constituting the microlens array is composed of two or more types of microlenses having different inclination angles of the bottom surface of the microlens with respect to the plane parallel to the light receiving surface, and the effective imaging area is divided into a plurality of partial areas from the center toward the periphery. The plurality of partial areas include partial areas in which microlenses having different inclination angles are mixed, and a difference in inclination angles between adjacent microlenses is 10 ° or less. Solid-state image sensor.   4. The solid according to claim 3, wherein the mixing ratio of the microlenses having different inclination angles in the partial area changes along the direction from the center of the effective imaging area toward the periphery in the partial area. Image sensor.   The solid-state image pickup device according to claim 3, wherein a mixing ratio of microlenses having different inclination angles in the partial area is substantially uniform in the partial area.   The solid-state imaging device according to claim 3, wherein microlenses having different inclination angles are randomly arranged in the partial region.   The solid-state imaging device according to claim 1, wherein the average inclination angle of the microlens tends to increase from the center of the effective imaging region toward the periphery.   The solid-state imaging device according to claim 1, wherein the partial region has a mosaic shape.   The solid-state imaging device according to any one of claims 1 to 7, wherein the partial region is a concentric annular region centered on an effective imaging region center.   An imaging apparatus comprising the solid-state imaging device according to claim 1.

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