JP2018037623A - Solid state imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease crosstalk (color mixture) between pixel pairs adjacent in the vertical direction and a reduction in sensitivity of image surface phase difference pixels arranged behind one micro-lens.SOLUTION: In a solid state imaging device, one micro-lens 11, and image surface phase difference pixels that is a pixel pair formed by including one pair of a first pixel and a second pixel arranged behind the one micro-lens 11, are arranged in plurality adjacent to each other in the vertical direction and horizontal direction on a plane. The solid state imaging device comprises: a peripheral part light blocking film 16 that is arranged to surround a peripheral part of the pixel pair on the plane; a device separation area part 13 that is provided in an area of each of the pixel pair 12 where the first pixel and second pixel are adjacent to each other; and a projecting light blocking film 17 that is arranged projecting from a portion of each of the pixel pair 12 at which the peripheral part light blocking film 16 and the device separation area part 13 intersect with each other on the plane toward the central part of the device separation area part 13.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a solid-state image sensor constituted by a CMOS image sensor or the like, and more particularly to a solid-state image sensor provided with a mechanism for AF (autofocus) processing by a phase difference detection method.

  As a conventional solid-state imaging device having a mechanism for AF processing, one described in Patent Document 1 is known. This solid-state imaging device is formed on a semiconductor substrate, photoelectrically converts a photoelectric conversion portion of incident light, is formed in an upper layer of the photoelectric conversion portion, and guides the incident light to the photoelectric conversion portion, and near the opening of the waveguide And a phase difference detection pixel having a light shielding portion for shielding a part of incident light incident on the waveguide. As a result, the distance measurement accuracy can be improved along with the ease of processing.

  Patent Document 2 discloses a solid-state imaging device and a method for manufacturing the solid-state imaging device that can improve the light receiving sensitivity without thinning the light shielding portion. The solid-state imaging device according to the invention of Patent Document 2 includes a semiconductor layer and a light shielding portion. In the semiconductor layer, a plurality of photoelectric conversion elements are arranged in a two-dimensional array. The light shielding part is provided inside the semiconductor layer and has a light shielding member whose interface with the semiconductor layer is covered with an insulating film. Furthermore, the light shielding part includes a light shielding region and an element isolation region. The light shielding region is provided on the light receiving surface side of the photoelectric conversion element inside the semiconductor layer, and blocks light incident on the photoelectric conversion element from a specific direction. The element isolation region is provided so as to protrude from the light shielding region to the space between the plurality of photoelectric conversion elements in the depth direction of the semiconductor layer so as to electro-optically isolate the plurality of photoelectric conversion elements.

  Furthermore, in the invention of Patent Document 3, a trench 71 is formed between the photodiodes 24 (element isolation regions) of the phase difference detection pixels 40L and 40R on the silicon substrate 23. Further, trenches 72 are formed between the photodiodes 24 of the imaging pixels adjacent to the phase difference detection pixel 40L and between the photodiodes 24 of the imaging pixels adjacent to the phase difference detection pixel 40L.

  According to the structure of the above-mentioned patent document 3, the trench 71 can suppress color mixing between the adjacent phase difference detection pixels 40L and 40R, and the trench 72 can reduce the phase difference detection pixels 40L and 40R, respectively. Color mixing between adjacent imaging pixels 20 can be suppressed.

Japanese Patent Laying-Open No. 2015-15296 JP2015-32640A Japanese Patent Laying-Open No. 2015-60855

  Further, as shown in FIGS. 1 and 2, a pixel pair 102 including one microlens 101 and a first pixel 102 </ b> L and a second pixel 102 </ b> R disposed behind the one microlens 101. There is known a solid-state imaging device including an image plane phase difference pixel configured by: This solid-state imaging device has a configuration in which a plurality of microlenses 101 and pixel pairs 102 are arranged adjacent to each other in a vertical direction and a horizontal direction on a plane.

  In the above-described solid-state imaging device, in each pixel pair 102, the region C between the first pixel 102L and the second pixel 102R and the bottom and side portions of the first pixel 102L and the second pixel 102R, An element isolation region 103 is provided. A light shielding film 104 is disposed on the element isolation region 103.

  In the solid-state imaging device as described above, as shown in FIG. 2, the light l arriving from above the central portion of one microlens 101 is blocked by the light shielding film 104 disposed above the region C. As a result, this solid-state imaging device has a problem that sensitivity is lowered.

  In contrast to the above, as shown in FIGS. 3 and 4, the solid-state imaging device having the configuration shown in FIGS. 1 and 2 is configured by removing the light-shielding film 104 disposed above the region C. . 3 and 4 show two pairs in which the pixel pair 102 is adjacent in the vertical direction in the plane.

  In the above configuration, the electrons e are generated as shown in FIG. 4 by the light l incident on one element isolation region 103 in two pairs adjacent in the vertical direction. There is a problem that this electron e reaches the other adjacent pixel pair 102 and crosstalk (color mixing) occurs.

  Further, in order to improve crosstalk (color mixing), in the solid-state imaging device having the configuration shown in FIGS. 1 and 2, only the adjacent position in the pixel pair 102 adjacent in the vertical direction of the plane is arranged above the element isolation region. It is considered that the width of the light shielding film 104W formed is wide (FIGS. 5 and 6).

  According to the solid-state imaging device having this configuration, the light l incident from above the wide light shielding film 104W is blocked by the light shielding film 104W and cannot reach the first pixel 102L (second pixel 102R). There is a problem of lowering.

  The present invention has been made as a solution to the problems of such a solid-state imaging device, and its purpose is to arrange crosstalk (color mixing) between pixel pairs adjacent in the vertical direction or behind one microlens. It is an object of the present invention to provide a solid-state imaging device capable of reducing a decrease in sensitivity in an image plane phase difference pixel.

  The solid-state imaging device according to the present invention is an image plane position that is a pixel pair configured to include one microlens and one set of a first pixel and a second pixel disposed behind the one microlens. In a solid-state imaging device in which a plurality of phase difference pixels are arranged adjacent to each other in a vertical direction and a horizontal direction in a plane, a peripheral portion light shielding film disposed so as to surround the peripheral portion of the pixel pair in the plane, and the pixel pair in each pixel pair The element isolation region portion provided in a region where the first pixel and the second pixel are adjacent to each other, and the element isolation from a portion where each of the pixel light pairs intersects the peripheral portion light shielding film and the element isolation region portion in a plane. And a projecting light-shielding film disposed so as to project toward the center of the region.

  In the solid-state imaging device according to the present invention, the peripheral edge light shielding film and the protruding light shielding film are integrally formed.

  In the solid-state imaging device according to the present invention, the peripheral edge light-shielding film is formed with the same width at any position on the plane.

  In the solid-state imaging device according to the present invention, the dimension of the projecting light-shielding film in the projecting direction is set to a length that can prevent crosstalk occurring in adjacent pixel pairs.

  In the solid-state imaging device according to the present invention, in each pixel pair, one color filter is interposed between the one microlens, the set of the first pixel, and the second pixel. It is characterized by.

  The solid-state imaging device according to the present invention is characterized in that the color filter color of each pixel pair is a Bayer array for all pixel pairs.

  The solid-state imaging device of the present invention includes an image plane phase difference that is a pixel pair including one microlens, and a first pixel and a second pixel disposed behind the one microlens. In a solid-state imaging device in which a plurality of pixels are arranged adjacent to each other in a vertical direction and a horizontal direction on a plane, a peripheral portion light-shielding film disposed so as to surround the peripheral portion of the pixel pair on the plane, and the first in each pixel pair The element isolation region portion provided in a region where the second pixel and the second pixel are adjacent to each other, and the element isolation region portion from a portion where the peripheral light shielding film and the element isolation region portion intersect in a plane in each pixel pair A projecting light-shielding film disposed so as to project toward the central portion of the pixel, so that crosstalk (color mixing) between pixel pairs adjacent in the vertical direction and a set of firsts disposed behind one microlens. Pixels The reduction in sensitivity in the second pixel, it is possible to reduce.

The top view of the solid-state image sensor which concerns on a 1st prior art example. II sectional drawing of FIG. The top view of the solid-state image sensor which concerns on a 2nd prior art example. II-II sectional drawing of FIG. The top view of the solid-state image sensor concerning a 3rd prior art example. III-III sectional drawing of FIG. The top view of the embodiment of the solid-state image sensing device concerning the present invention. AA sectional drawing of FIG. BB sectional drawing of FIG. The top view which shows the arrangement | sequence of the color filter of embodiment of the solid-state image sensor which concerns on this invention. The top view of only the light shielding film of embodiment of the solid-state image sensor which concerns on this invention.

  Embodiments of a solid-state imaging device according to the present invention will be described below with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description is omitted. FIG. 7 shows a plan view of an embodiment of a solid-state imaging device according to the present invention, FIG. 8 shows a cross-sectional view along AA, and FIG. 9 shows a cross-sectional view along BB. The solid-state imaging device according to the present embodiment includes a CMOS image sensor or the like, and includes one microlens 11, a first pixel (photodiode) 12L disposed behind the one microlens 11, and a second. A plurality of image plane phase difference pixels, which are pixel pairs 12 including one set of pixels (photodiodes) 12R, are arranged adjacent to each other in the vertical and horizontal directions on a plane. In FIG. 7, two pixel pairs 12 adjacent in the vertical direction are shown. The first pixel 12L and the second pixel 12R of all the pixel pairs 12 are used as, for example, an image plane phase difference pixel in the AF process before the imaging process, and all the same pixels in the imaging process. The first pixel 12L and the second pixel 12R of the pair 12 are used as an image sensor.

  Each set of the first pixel 12L and the second pixel 12R is provided with an element isolation region 13 at the bottom and side walls thereof. The top surfaces of the pair of first pixels 12L and second pixels 12R and the top surface of the element isolation region 13 are set to the same height.

  A planarization layer 14 is provided between one microlens 11 and a pair of first pixel 12L and second pixel 12R. A color filter 15 having a size covering the surface area of the pair of the first pixel 12L and the second pixel 12R is interposed at an upper position in the planarization layer 14. That is, one color filter is interposed between the one microlens 11 and the one set of the first pixel 12L and the second pixel 12R.

  The color of the color filter 15 of each pixel pair 12 can be a Bayer array as shown in FIG. 10 for all pixel pairs. In FIG. 10, R represents a color filter that transmits red, G represents a color filter that transmits green, and B represents a color filter that transmits blue. The Bayer arrangement is only an example.

  A peripheral portion light shielding film 16 is disposed so as to surround the peripheral portion of the planar pixel pair 12. As shown in FIG. 11, which is a plan view of only the light shielding film, the peripheral edge light shielding film 16 is formed to have the same width at any position.

  In each pixel pair 12, a projecting light shielding film 17 projects from a portion X (FIG. 7) where the peripheral light shielding film 16 and the element isolation region 13 intersect at a plane toward the center of the element isolation region 13. Are arranged. As is apparent from FIG. 11, which is a plane of only the light shielding film constituted by the peripheral light shielding film 16 and the protruding light shielding film 17, the peripheral light shielding film 16 and the protruding light shielding film 17 are integrally formed. The dimension of the protruding light shielding film 17 in the protruding direction is set to a length that can prevent crosstalk occurring in the adjacent pixel pair 12.

  That is, electrons e are generated in the element isolation region 13 by the light incident from the microlenses 11 of one adjacent pixel pair 12, but are incident so that the electrons e do not reach the other adjacent pixel pair 12. It is only necessary that the protruding light shielding film 17 protrudes to a length that can block light to be transmitted. If the length is closer to the center than this, the sensitivity is lowered, so the above dimensions are preferable.

  Further, since the peripheral edge light shielding film 16 surrounds the peripheral edge of the pixel pair 12, in each adjacent pixel pair 12, light incident from the microlens 11 toward the peripheral edge light shielding film 16 can be blocked. it can.

  In the solid-state imaging device according to the present embodiment configured as described above, in the two pairs of pixels 12 adjacent in the vertical direction, as illustrated in FIG. 8, the element isolation region is separated from the microlens 11 of one pixel pair 12. Even if the light l is incident on the portion 13, the protruding light shielding film 17 blocks further intrusion. That is, as shown in FIG. 4, electrons e are not generated, and crosstalk (color mixing) can be suppressed.

  Further, in the vicinity of the adjacent portion of the adjacent pixel pair 12, the light l incident from the microlens 11 of the pixel pair 12 proceeds to the first pixel 12L (second pixel 12R) without being blocked. be able to. That is, as shown in FIG. 6, the incident light l is not blocked by the peripheral light shielding film 16. For this reason, it is possible to suppress a decrease in sensitivity due to the fact that the light l as described above cannot reach the first pixel 12L (second pixel 12R).

DESCRIPTION OF SYMBOLS 11 Micro lens 12 Pixel pair 12L 1st pixel 12R 2nd pixel 13 Element isolation region part 14 Flattening layer 15 Color filter 16 Peripheral part light shielding film 17 Protruding light shielding film

Claims (6)

One microlens and an image plane phase difference pixel that is a pixel pair including one set of a first pixel and a second pixel disposed behind the one microlens are arranged in a vertical direction on a plane. And a solid-state imaging device arranged in a plurality of lateral directions,
A peripheral light shielding film disposed so as to surround the peripheral edge of the pixel pair in a plane;
In each pixel pair, an element isolation region provided in a region where the first pixel and the second pixel are adjacent to each other;
In each pixel pair, the peripheral light-shielding film and the element isolation region part have a protruding light-shielding film disposed so as to protrude from a portion where the element isolation region part intersects in a plane toward the center of the element isolation region part. A solid-state imaging device.   The solid-state imaging device according to claim 1, wherein the peripheral light shielding film and the protruding light shielding film are integrally formed.   3. The solid-state imaging device according to claim 1, wherein the peripheral edge light-shielding film is formed with the same width at any position on a plane.   4. The solid-state imaging device according to claim 1, wherein a dimension of the projecting light shielding film in a projecting direction is a length capable of preventing crosstalk generated in adjacent pixel pairs.   5. In each pixel pair, one color filter is interposed between the one microlens, the set of the first pixel, and the second pixel. The solid-state image sensor of any one of these. 6. The solid-state image pickup device according to claim 5, wherein the color filter color of each pixel pair is a Bayer array for all pixel pairs.