JP2007288107A - Solid imaging device and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid imaging device capable of miniaturizing and thinning a camera without deteriorating color-shading characteristics. <P>SOLUTION: The solid imaging device has a plurality of light receiving sections each constituting a light receiving surface, a plurality of color filters corresponding to a plurality of the light receiving sections, and a plurality of micro-lenses corresponding to a plurality of the color filters, the color filters at the central section of the light receiving section are positioned right above the light receiving sections corresponding thereto, a plurality of the color filters includes a plurality of first color filters, a plurality of second color filters, and a plurality of third color filters of each different color, the positions of each color filter in the peripheral sections of the light receiving surfaces are deviated in the direction of the central section from the positions right above the light receiving section corresponding thereto, and at least a deviated amount of the first color filter is different from that of the adjacent second color filter or the third color filter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and a camera with improved shading amount, particularly color shading.

  In recent years, there has been an increasing demand for downsizing and high performance of digital still cameras (hereinafter referred to as DSC) digital movie cameras (hereinafter referred to as movies), mobile phones with cameras, and the like. For this reason, the reduction in the chip size and the increase in the number of pixels of the solid-state image pickup device proceed at the same time, and further the miniaturization and thinning of the camera progress, and the short exit pupil distance progresses. Here, the exit pupil refers to a virtual image of the lens (or diaphragm) viewed from the light receiving surface, and the exit pupil distance refers to the distance from the lens and the light receiving surface to the exit pupil.

Hereinafter, the solid-state imaging device described in Patent Document 1 will be described with reference to the drawings.
FIG. 5 is a schematic diagram showing a cross-section of a structure showing a conventional solid-state imaging device. This figure shows the relationship between the exit pupil distance and the light incident angle on the light receiving unit.

  Light enters through the camera lens 100. The light collected by the lens as in the optical path 101 is collected at a certain point and is incident on the light receiving surface of the solid-state imaging device 110 after that. Here, the distance from the focal point generated between the camera lens 100 and the solid-state imaging device 110 to the camera lens 110 is the exit pupil distance 102. The angle of light incident on the light receiving surface of the solid-state imaging device 110 is determined by the exit pupil distance 102. While the incident angle at the central portion of the light receiving surface is substantially vertical, the incident angle to the peripheral portion is as small as the outermost peripheral incident angle 103. As the camera becomes smaller and thinner, the exit pupil distance 102 also becomes shorter. As the exit pupil distance 102 decreases, the outermost peripheral incident angle 103 further increases.

  Thus, the shorter the exit pupil distance, the larger the outermost peripheral incidence angle. With the recent thinning of cameras, the outermost peripheral incidence angle is becoming larger.

  Since the light to the peripheral pixels becomes oblique light, the output is lower than that of the central pixel. The behavior in which the output of peripheral pixels decreases with respect to the center of the effective pixel is called “shading”. Shading is a factor that significantly reduces image quality.

  The solid-state imaging device of the prior art disclosed in Patent Document 1 reduces the output reduction of peripheral pixels by shifting the position of the color filter in the peripheral part toward the central part.

Patent Document 2 discloses a solid-state imaging device provided with a refractive index correction layer for correcting the refractive index for each filter as a measure against shading.
JP 2001-160973 A JP2005-101266

  In general, the color filter of a solid-state imaging device has a different refractive index for each of a red filter, a green filter, and a blue filter. Therefore, even if the position of the color filter is shifted as in the prior art solid-state imaging device shown in Patent Document 1, since the condensing position of each color filter is different, the output ratio of each filter is set to the central portion. Therefore, there is a first problem that color shading characteristics in which colors are balanced cannot be obtained.

  To deal with this problem, it is conceivable to provide a refractive index correction layer for correcting the refractive index for each color filter as in Patent Document 2, but in this case, the refractive index correction layer increases the film thickness and further increases the refractive index. There is a second problem that the light is attenuated by the transmittance of the rate correction layer itself and the sensitivity characteristic may be deteriorated.

  In view of the above problems, an object of the present invention is to provide a solid-state imaging device and a camera capable of reducing the size and thickness of a camera without deteriorating color shading characteristics.

  In order to solve the above-described problem, a solid-state imaging device according to the present invention includes a plurality of light receiving units that form a light receiving surface, a plurality of color filters corresponding to the plurality of light receiving units, and a plurality of micros corresponding to the plurality of color filters. A solid-state imaging device having a lens, wherein the color filter at a central portion of the light receiving surface is located immediately above the corresponding light receiving portion, and the plurality of color filters have a first color and a second color different from each other. Each of the color filters in the peripheral portion of the light receiving surface is shifted from the position immediately above the corresponding light receiving portion toward the central portion, The shift amount of the color filter of the first color is different from the shift amount of the color filter of the adjacent second color. According to this configuration, since the color filter shift amount can be set optimally for each color in the peripheral portion of the light receiving surface, the light collection efficiency to the light receiving unit can be improved. As a result, the occurrence of color shading can be prevented. Therefore, the exit pupil distance can be shortened, and the camera can be reduced in size and thickness.

  Here, the microlens in the central portion of the light receiving surface is located directly above the corresponding light receiving portion, and the position of the microlens in the peripheral portion of the light receiving surface is from the position directly above the corresponding light receiving portion to the center. The displacement amount of the micro lens corresponding to at least the first color filter is different from the displacement amount of the micro lens corresponding to the adjacent second color filter. Also good. According to this configuration, since the shift amount of the microlens is optimized for each color of the corresponding color filter, the light collection efficiency to the light receiving unit can be improved for each color. As a result, the occurrence of color shading can be prevented. Therefore, the exit pupil distance can be shortened, and the camera can be reduced in size and thickness.

  Here, the shift amount may be different depending on the colors of the first, second, and third color filters, or may be different from each refractive index of the first, second, and third color filters. Different configurations may be used.

  Here, the plurality of color filters include three types of first, second, and third color filters, and the refractive index of the first color filter is smaller than that of the second color filter, and the second color filter The refractive index of the color filter is smaller than that of the third color filter, the shift amount of the first color filter is smaller than that of the second color filter, and the shift amount of the second color filter is the first shift amount. You may comprise so that it may be smaller than 3 color filters.

  The plurality of color filters include three types of first, second, and third color filters, and the refractive index of the first color filter is the same as that of the second color filter, and the second color filter The refractive index of the color filter is smaller than that of the third color filter, the shift amount of the first color filter is the same as that of the second color filter, and the shift amount of the second color filter is You may comprise so that it may be smaller than a 3rd color filter.

  Here, the plurality of color filters include three types of first, second, and third color filters, and the refractive index of the first color filter is smaller than that of the second color filter, and the second color filter The refractive index of the color filter is the same as that of the third color filter, the shift amount of the first color filter is smaller than that of the second color filter, and the shift amount of the second color filter is You may comprise so that it may be the same as a 3rd color filter.

  The solid-state imaging device may be a MOS solid-state imaging device having two or more metal wiring layers.

  Since the camera of the invention includes the above-described solid-state imaging device, the same effects as described above can be obtained.

  In the solid-state imaging device of the present invention, any color can be condensed on the light receiving portion in the same manner even in the peripheral portion of the effective pixel portion. As a result, the occurrence of color shading can be prevented. Therefore, the exit pupil distance can be shortened, and the camera can be reduced in size and thickness.

  Since the solid-state imaging device of the present invention can optimize the difference in the condensing state in the light receiving portion due to the difference in the refractive index of the color filter to the substantial light incident angle after the color filter, Any color can be similarly focused on the light receiving part.

  As a result, the color balance in the peripheral portion is the same as that in the center, and the occurrence of color shading can be prevented.

Therefore, it greatly contributes to shortening of the exit pupil position, that is, downsizing and thinning of the camera.
Note that the structure of the present invention is particularly effective when the light receiving portion is composed of two or more metal wiring layers.

  The same advantage can be obtained with a camera equipped with the solid-state imaging device of the present invention.

(First embodiment)
In the solid-state imaging device according to the present embodiment, the color filter in the central portion of the light receiving surface is positioned directly above the corresponding light receiving portion, and the position of each color filter in the peripheral portion of the light receiving surface is directly above the corresponding light receiving portion. It is shifted from the position toward the central portion, and the shift amount of each color filter is different from the shift amount of the adjacent color filters of other colors.

  FIG. 1 is a top view showing an example of the solid-state imaging device of the present invention. The left side of the figure shows the arrangement of the color filters on the light receiving surface 10 of the solid-state imaging device, and the right side of the figure shows an enlarged view of the broken line frame part at the lower right side of the left side. FIG. 2 is a cross-sectional view illustrating an example of a solid-state imaging device.

  The light receiving surface 10 represents an imaging region composed of effective pixels excluding optical black pixels. A plurality of light receiving portions 18 formed on a semiconductor substrate and arranged in a matrix, a color filter group 11 composed of a plurality of color filters corresponding to the plurality of light receiving portions 18, and a plurality of micros corresponding to the plurality of color filters. And a lens 15. Further, as shown in FIG. 2, the solid-state imaging device has a first layer wiring 16 and a second layer wiring 17.

  The color filter group 11 includes a plurality of color filters of a first color, a second color, and a third color, each having a different color. In the figure, the color filter group 11 includes three types: a red filter 12, a green filter 13, and a blue filter 14. Become.

  The color filter in the central portion of the light receiving surface 10 is located immediately above the corresponding light receiving portion 18. On the other hand, the position of each color filter in the peripheral part of the light receiving surface 10 is shifted from the position directly above the corresponding light receiving part in the direction of the center part (shift direction in the figure). That is, the deviation amounts of the adjacent red filter 12, green filter 13, and blue filter 14 in the peripheral part are not the same but differ for each color.

  Further, the microlens 15 in the central portion of the light receiving surface 10 is positioned directly above the corresponding light receiving portion 18, and the position of the microlens 15 in the peripheral portion of the light receiving surface 10 is from the position directly above the corresponding light receiving portion 18. They are arranged so as to be shifted in the center direction. The amount of deviation of the microlens 15 corresponding to the red filter 12 is different from the amount of deviation of the microlens 15 corresponding to the adjacent color filters of other colors. The same applies to each microlens corresponding to the green filter 13 and the blue filter 14.

  As described above, the adjacent color filters of different colors and the microlenses 15 located at substantially the same place are arranged with different amounts of deviation for each color, so that the solid-state imaging device of the present invention can detect oblique light. Any color can be condensed at the center of each light receiving portion 18.

  Specifically, the solid-state imaging device of the present embodiment shows a configuration when the relationship between the refractive indexes of the color filters is (Equation 1). nr, ng, and nb are the refractive indexes of the red filter 12, the green filter 13, and the blue filter 14, respectively.

  nr> ng> nb (Equation 1)

In this case, the shift amount of the color filter is (Equation 2a). Sr, Sg, and Sb are deviation amounts of the red filter 12, the green filter 13, and the blue filter 14, respectively, as shown in FIG. The amount of deviation is a horizontal distance between the center of the light receiving unit 18 and the center of the color filter (12, 13 or 14) indicated by a one-dot chain line.

  Sr> Sg> Sb (Equation 2a)

Further, the amount of deviation of the microlens is (Equation 2b). Mr, Mg, and Mb are deviation amounts of the microlenses corresponding to the red filter 12, the green filter 13, and the blue filter 14, respectively, as shown in FIG. The amount of deviation is a horizontal distance between the center of the light receiving unit 18 indicated by the one-dot chain line and the center of the microlens indicated by the two-dot chain line.

  Mr> Mg> Mb (Equation 2b)

  2, in the solid-state imaging device of the present embodiment, the red filter 12 has the largest deviation amount with respect to the center of the light receiving unit 18 of each pixel. Thereby, the light passing through the red filter 12 is changed by the red filter 12 having the highest transmittance, and is condensed on the light receiving unit 18.

  Further, if the amount of deviation of the green filter 13 is equal to or less than the red filter 12, the green light is condensed at the center of the light receiving unit 18.

  Further, when the blue filter 14 is equal to or less than the green filter 13, the blue filter 14 is also condensed at the center of the light receiving unit 18.

  The general acrylic resin forming the color filter has a red filter 12 of 1.66, a green filter 13 of 1.56, and a blue filter 14 of about 1.52.

  Further, there is no change in the amount of shift in each pixel. For example, when the green filter is based on the light collection position of the light receiving unit 18 by 13, the light collection position of the red filter 12 is 0.3 μm, and the light collection position of the blue filter 14 Is shifted by 0.1 μm.

  Therefore, when the pixel size is 3 μm or more (a light receiving portion of 1.5 μm or more can be secured), the change in the condensing position due to this refractive index difference does not cause a problem.

  However, on the other hand, when the pixel size is 2.0 μm or less, the light receiving portion is less than 1.0 μm, and thus the influence of the change in the condensing position becomes large.

  As described above, the solid-state imaging device according to the embodiment of the present invention is particularly effective when the pixel size is 2.0 μm or less.

  Furthermore, the solid-state imaging device according to the embodiment of the present invention has improved characteristics particularly with respect to the MOS solid-state imaging device in which the distance (thickness) between the light receiving unit 18 and each color fill is longer than that of the CCD solid-state imaging device. Great effect.

  Details of the reason will be described with reference to FIG. FIG. 3 is a cross-sectional structure comparison diagram between a CCD solid-state imaging device and a MOS solid-state imaging device.

  From FIG. 3, the distance (thickness) between the light receiving portion and the color filter of the MOS type solid-state imaging device is longer than that of the CCD solid-state imaging device. This is because a metal wiring layer is disposed between the light receiving portion and the color filter, and control and signal transmission of each pixel are performed.

  Here, if the incident angle of light is θ and the distance (thickness) T between the light receiving part and the color filter is T, the shift amount Δd is (Equation 3).

  Δd = T × tan θ (Equation 3)

  That is, it can be seen that the shift amount Δd also needs to be increased as the thickness of T increases.

Further, when the refractive index difference of the color filter occurs, the angle of the optical path to the light receiving portion changes.
Therefore, the deterioration of the shading characteristic with respect to the refractive index difference of the color filter is easily affected by the MOS type solid-state imaging device having a long distance (thickness) between the light receiving portion and the color filter.

  For this reason, as in the solid-state imaging device of the present invention, each filter and microlens are shifted by a predetermined amount so that the oblique light is condensed at the center of the light receiving unit 18, and the shift amount of each color filter is changed to the red filter 12. The solid-state imaging device according to the present invention in which the shift amount is different for each of the corresponding pixel, the pixel corresponding to the green filter 13, and the pixel corresponding to the blue filter 14, has an effect of improving characteristics particularly with respect to the MOS type solid-state imaging device. large.

  As described above, the effect of the present invention is greater in the MOS type solid-state imaging device than in the CCD type solid-state imaging device. The present invention can be applied to the solid-state imaging device according to the above embodiment as long as each pixel includes a light receiving unit, a color filter corresponding to the light receiving unit, and a microlens. The circuit format is not limited.

  Although the adjacent color filters partially overlap on the right side of FIG. 1, it is desirable that they do not overlap. Further, although there is a gap between adjacent color filters, it is desirable to provide a light shielding film under the gap.

(Second Embodiment)
The solid-state imaging device according to the second embodiment of the present invention will be described below.

  In the solid-state imaging device of the present embodiment, the color filter at the center of the light receiving surface is located directly above the corresponding light receiving unit, and the position of each color filter at the periphery of the light receiving surface is directly above the corresponding light receiving unit. It is shifted from the position in the direction of the central portion, and the shift amount of the blue color filter is different from the shift amount of the color filters of other adjacent colors.

  Since the configuration of the solid-state imaging device according to the present embodiment is the same as that of the solid-state imaging device according to the first embodiment except for the following points, different points will be mainly described. The difference is the refractive index and the shift amount of the color filter.

  In this embodiment, the relationship between the refractive indexes of the color filters is (Equation 4). nr, ng, and nb are the refractive indexes of the red filter 12, the green filter 13, and the blue filter 14, respectively.

  nr = ng> nb (Equation 4)

  At this time, the shift amount of the color filter is (Equation 5a). Sr, Sg, and Sb are deviation amounts of the red filter 12, the green filter 13, and the blue filter 14, respectively.

  Sr = Sg> Sb (Equation 5a)

  Further, the amount of deviation of the microlens is (Equation 5b). Mr, Mg, and Mb are the shift amounts of the micro lenses corresponding to the red filter 12, the green filter 13, and the blue filter 14, respectively.

  Mr = Mg> Mb (Equation 5b)

  In addition, when a special material having a low refractive index (for example, an acrylic resin having a refractive index of 1.56) is used for the red filter 12, it is possible to particularly suppress the occurrence of red color shading.

  Conversely, the refractive indexes of the green filter 13 and the blue filter 14 may be increased.

(Third embodiment)
A solid-state imaging device according to the third embodiment of the present invention will be described below.

  In the solid-state imaging device of the present embodiment, the color filter at the center of the light receiving surface is located directly above the corresponding light receiving unit, and the position of each color filter at the periphery of the light receiving surface is directly above the corresponding light receiving unit. It is shifted from the position in the direction of the central portion, and the shift amount of the red color filter is different from the shift amount of the adjacent color filters of other colors.

  Since the configuration of the solid-state imaging device according to the present embodiment is the same as that of the solid-state imaging device according to the first embodiment except for the following points, different points will be mainly described. The difference is the refractive index and the shift amount of the color filter.

  In this embodiment, the relationship between the refractive indexes of the color filters is (Equation 6). nr, ng, and nb are the refractive indexes of the red filter 12, the green filter 13, and the blue filter 14, respectively.

  nr> ng = nb (Formula 6)

  At this time, the shift amount of the color filter is (Equation 7a). Sr, Sg, and Sb are deviation amounts of the red filter 12, the green filter 13, and the blue filter 14, respectively.

  Sr> Sg = Sb (Formula 7a)

  Further, the amount of deviation of the microlens is (Equation 7b). Mr, Mg, and Mb are the shift amounts of the micro lenses corresponding to the red filter 12, the green filter 13, and the blue filter 14, respectively.

  Mr> Mg = Mb (Formula 7b)

  In addition, when a special material having a high refractive index (for example, an acrylic resin having a refractive index of 1.56) is used for the blue filter 14, it is possible to suppress the occurrence of blue color shading in particular.

Conversely, the refractive indexes of the red filter 12 and the green filter 13 may be lowered.
The other device configuration is the same as that of the solid-state imaging device according to the first embodiment shown in FIG.

  As described above, if the solid-state imaging device according to each of the above embodiments is a solid-state imaging device in which each pixel includes a light receiving unit, a color filter corresponding to the light receiving unit, and a microlens, the structure and circuit format of each pixel Is not limited. However, as will be described later, the effect is greater in the case of a MOS solid-state imaging device than a CCD solid-state imaging device.

  The present invention is suitable for a solid-state imaging device having a microlens and a color filter in each of a plurality of light-receiving portions formed on a semiconductor substrate, and a camera related to the solid-state imaging device, and in particular, a MOS solid-state imaging device and a CCD solid-state imaging device. It is suitable for imaging devices, digital still cameras, mobile phones with cameras, cameras built into notebook computers, information processing equipment, medical cameras that require ultra-miniaturization, capsule cameras, and the like.

1 is a plan view of a solid-state imaging device according to a first embodiment of the present invention. It is sectional drawing of the solid-state imaging device in the embodiment. It is sectional drawing for the comparison of a CCD type solid-state imaging device and a MOS type solid-state imaging device. It is a block diagram which shows the structure of a camera. It is structure sectional drawing which showed the solid-state imaging device of the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light-receiving surface 11 Color filter group 12 Red filter 13 Green filter 14 Blue filter 15 Micro lens 16 1st layer wiring 17 2nd layer wiring 18 Light-receiving part 19 Filter position at the time of no shift 100 Camera lens 101 Optical path 102 Exit pupil distance 103 Maximum Outer incidence angle 110 Solid-state imaging device

Claims (9)

A plurality of light receiving parts constituting the light receiving surface;
A plurality of color filters corresponding to the plurality of light receiving units;
A solid-state imaging device having a plurality of microlenses corresponding to the plurality of color filters,
The color filter in the central portion of the light receiving surface is located directly above the corresponding light receiving portion,
The plurality of color filters each include a plurality of color filters of a first color, a second color, and a third color having different colors,
The position of each color filter in the periphery of the light receiving surface is shifted from the position directly above the corresponding light receiving portion toward the central portion,
A solid-state imaging device characterized in that the shift amount of at least the first color filter is different from the shift amount of the adjacent second or third color filter. The microlens in the central part of the light receiving surface is located directly above the corresponding light receiving part,
In the peripheral part of the light receiving surface, the position of the microlens is shifted from the position directly above the corresponding light receiving part toward the central part.
The shift amount of the micro lens corresponding to at least the first color filter is different from the shift amount of the micro lens corresponding to the adjacent second color filter. Solid-state imaging device.   The solid-state imaging device according to claim 1, wherein the shift amount differs according to each color of the first, second, and third color filters.   The solid-state imaging device according to claim 1, wherein the shift amount differs according to each refractive index of the first, second, and third color filters. The plurality of color filters include three types of first, second and third color filters,
The refractive index of the first color filter is smaller than that of the second color filter,
The refractive index of the second color filter is smaller than that of the third color filter,
The shift amount of the first color filter is smaller than that of the second color filter,
The solid-state imaging device according to claim 1, wherein the shift amount of the second color filter is smaller than that of the third color filter. The plurality of color filters include three types of first, second and third color filters,
The refractive index of the first color filter is the same as that of the second color filter,
The refractive index of the second color filter is smaller than that of the third color filter,
The shift amount of the first color filter is the same as that of the second color filter,
The solid-state imaging device according to claim 1, wherein the shift amount of the second color filter is smaller than that of the third color filter. The plurality of color filters include three types of first, second and third color filters,
The refractive index of the first color filter is smaller than that of the second color filter,
The refractive index of the second color filter is the same as that of the third color filter,
The shift amount of the first color filter is smaller than that of the second color filter,
The solid-state imaging device according to claim 1, wherein the shift amount of the second color filter is the same as that of the third color filter.   2. The solid-state image pickup device according to claim 1, wherein the solid-state image pickup device is a MOS type solid-state image pickup device having two or more metal wiring layers.   A camera comprising the solid-state imaging device according to claim 1.

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