JP6776079B2 - Solid-state image sensor and its manufacturing method - Google Patents

Description

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

In the above-mentioned solid-state image sensor, crosstalk and color mixing are problems, and for example, Patent Documents 1 and 2 disclose the problems and solutions.

Patent Document 1 discloses a solid-state image sensor that prevents color mixing and sensitivity unevenness by preventing an increase in the amount of light received by adjacent pixels due to reduction and shifting of the microlens of the phase difference detection pixel.

Specifically, the solid-state image sensor 11 has a configuration in which a dummy microlens 21 is formed in a gap portion formed around the second microlens L2 and the third microlens L3. Further, since the dummy microlens 21 acts as a stopper for the spread in the radial direction when forming the microlens L1, the microlens L1 is said to be formed in a shape that should be originally formed. It has a configuration. Therefore, the light a incident on the portion outside the originally formed shape is not focused on the photodiode PD, and as a result, the amount of received light received by the adjacent pixels of the dummy microlens 21 is prevented from increasing. You can do it.

Patent Document 2 describes a solid-state image sensor that solves the problem of improving pupil division performance and improving focus detection accuracy while suppressing a decrease in the amount of signals in a solid-state image sensor incorporated in an electronic camera. It is disclosed.

In the solid-state image sensor disclosed in Patent Document 2, the focus detection pixel 2A that detects only the light from the right pupil is an optical multilayer film 21A via a gate oxide film 29 directly above the right half of the charge storage unit 27A. Is formed. Further, in the focus detection pixel 2B that detects only the light from the left pupil, an optical multilayer film 21B is formed directly above the left half of the charge storage unit 27B via a gate oxide film 29. As a result, it is possible to avoid a situation in which the amount of signals is reduced during focus detection by the pupil division phase difference method, and at the same time, suppress the occurrence of crosstalk. According to the invention described in Reference Document 2, since the focus detection pixel has a light-shielding member (optical multilayer film) formed on half of the focus detection pixel, there is a problem that the sensitivity of the focus detection pixel itself is lowered. Further, the solid-state image sensor described in Reference Document 2 has a different structure of image plane phase difference pixels from that of the present invention, and cannot be simply called prior art.

Japanese Unexamined Patent Publication No. 2011-49472 Japanese Unexamined Patent Publication No. 2009-99817

A solid-state imaging device including a plurality of pixel pairs including one microlens and a set of image plane phase-difference pixels arranged behind the one microlens, as opposed to the conventional solid-state image sensor as described above. The element has the following problems related to crosstalk.

As shown in FIGS. 1, 2 and 3 (a), one microlens 101 and a set of a first pixel 102L and a second pixel 102R arranged behind the one microlens 101. A solid-state imaging device including an image plane phase difference pixel composed of a pixel pair 102 including the pixel pair 102 is known.

Each of the set of the first pixel 102L and the second pixel 102R is provided with an element separation region 103 at the bottom and the side wall, respectively. The upper surface of a set of the first pixel 102L and the second pixel 102R and the upper surface of the element separation region portion 13 have the same height. The peripheral edge light-shielding film 106 is arranged so as to surround the peripheral edge of the flat pixel pair 102. The peripheral edge light-shielding film 106 is formed, for example, having the same width.

FIG. 3B shows the potential distribution of the element separation region 103 in the adjacent two pairs of pixel pairs 102 with the corner at the lower left position of the element separation region 103 shown in FIG. 3A as a point at a distance of 0. .. The central portion in the longitudinal direction of the element separation region portion 103 in one pixel pair 102 is configured to have the maximum potential MP.

In a solid-state image sensor having such a configuration, in two pairs vertically adjacent to each other, electrons e are generated as shown in FIG. 3 by light l incident on one of the element separation region portions 103. There is a problem that the electron e reaches the other pixel pair 102 and crosstalk (color mixing) occurs.

The present invention has been made to solve the problems of such a solid-state image sensor, and an object of the present invention is to provide a solid-state image sensor capable of suppressing the occurrence of crosstalk (color mixing) between adjacent pixel pairs. It is to be.

The solid-state image sensor according to the present invention is an image plane position which is a pixel pair including one microlens and a pair of a first pixel and a second pixel arranged behind the one microlens. A plurality of phase difference pixels are solid-state image sensors arranged adjacent to each other in the vertical and horizontal directions in a plane, and in each pixel pair, the elements are located in a boundary region where the first pixel and the second pixel are adjacent to each other. In a solid-state image sensor in which a separation region portion is provided and the position of the maximum potential of the element separation region portion is set to a position near the end portion of the element separation region portion , the pixel pair is described in a plane. It is characterized in that a plurality of element separation region portions are arranged adjacent to each other so as to coincide with each other in the longitudinal direction .

The solid-state imaging device according to the present invention is characterized in that the element separation region portion has a long strip shape in a planar shape, and a position near both ends of the long strip shape is a position of maximum potential.

In the method for manufacturing a solid-state image sensor according to the present invention, in the ion implantation step of the element separation region portion, the dose amount at the time of ion implantation into the portion having the maximum potential is made smaller than the dose amount in other portions. It is a feature.

In the method for manufacturing a solid-state image sensor according to the present invention, a resist pattern in which an opening corresponding to a portion having a maximum potential is formed and an opening corresponding to the element separation region portion other than the portion having the maximum potential are formed. It is characterized by ion implantation using a resist pattern.

In the method for manufacturing a solid-state image sensor according to the present invention, ions are implanted using a resist pattern in which an opening corresponding to the element separation region portion other than the portion having the maximum potential is formed, and ions are implanted in the portion having the maximum potential. It is characterized by not injecting.

In the method for manufacturing a solid-state image sensor according to the present invention, a resist pattern having an opening having an area smaller than the area other than the portion having the maximum potential of the element separation region portion is used at a position corresponding to the portion having the maximum potential. It is characterized by ion implantation.

In the method for manufacturing a solid-state image sensor according to the present invention, the element separation region portion has a long strip-shaped planar shape, and both ends of the long strip-shaped slit are formed at positions corresponding to the portions having the maximum potential. It is characterized by ion implantation using a resist pattern that realizes a narrow opening with a small area.

In the method for manufacturing a solid-state image sensor according to the present invention, a plurality of openings are formed corresponding to positions corresponding to a portion having a maximum potential, and ions are used using a resist pattern in which openings having a small area as a whole are realized. It is characterized by injecting.

According to the present invention, the position of the maximum potential of the element separation region portion is set to a position near the end portion of the element separation region portion, so that crosstalk (color mixing) occurs between adjacent pixel pairs. It can be suppressed.

Top view of the solid-state image sensor according to the conventional example. The plan view of the solid-state image pickup device which concerns on the prior art which provided the peripheral part light-shielding film. FIG. 3A is a cross-sectional view taken along the line II of FIG. 2, and FIG. 3B is a diagram showing the potential distribution of the element separation region portion shown in FIG. 3A. The plan view of the embodiment of the solid-state image sensor according to the present invention. The plan view of the solid-state image pickup device which concerns on this invention, which provided the peripheral light-shielding film. FIG. 5A is a sectional view taken along the line AA of FIG. The plan view which shows the arrangement of the color filter of the embodiment of the solid-state image pickup device which concerns on this invention. 8 (a) is a cross-sectional view taken along the line BB of FIG. 5, and FIG. 8 (b) is a diagram showing the potential distribution of the element separation region portion shown in FIG. 8 (a). The plan view of the resist pattern used in the 1st Embodiment in the manufacturing method of the solid-state image pickup device which concerns on this invention. The plan view of the resist pattern used in the 2nd Embodiment in the manufacturing method of the solid-state image pickup device which concerns on this invention. The plan view of the resist pattern used in the 1st of the 3rd Embodiment in the manufacturing method of the solid-state image sensor which concerns on this invention. The plan view of the resist pattern used in the 2nd of the 3rd Embodiment in the manufacturing method of the solid-state image pickup device which concerns on this invention.

Hereinafter, embodiments of the solid-state image sensor according to the present invention will be described with reference to the accompanying drawings. In each figure, the same components are designated by the same reference numerals, and duplicate description will be omitted. FIG. 4 shows a plan view of an embodiment of the solid-state image sensor according to the present invention, FIG. 5 shows a plan view of an embodiment provided with a light-shielding film at a peripheral portion of the solid-state image sensor according to the present invention, and FIG. , AA sectional view is shown, and FIG. 8A shows a BB sectional view. The solid-state image sensor according to the present embodiment is composed of a CMOS image sensor or the like, and has one microlens 11, a first pixel (photodiode) 12L arranged 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 direction and the horizontal direction on a plane. In FIGS. 4 and 5, two pixel pairs 12 that are vertically adjacent to each other are shown. The first pixel 12L and the second pixel 12R of all the pixel pairs 12 are used as image plane phase difference pixels in the AF processing before the imaging process, and are also all the 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 of the set of the first pixel 12L and the second pixel 12R is provided with an element separation region portion 13 at the bottom portion and the side wall portion thereof, respectively. The upper surface of a set of the first pixel 12L and the second pixel 12R and the upper surface of the element separation region portion 13 have the same height.

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

The colors of the color filters 15 of each pixel pair 12 can be in a Bayer array as shown in FIG. 7 for all pixel pairs. In FIG. 7, R indicates a color filter that transmits red, G indicates a color filter that transmits green, and B indicates a color filter that transmits blue. The Bayer array is just one example.

The peripheral edge light-shielding film 16 is arranged so as to surround the peripheral edge of the flat pixel pair 12. As shown in FIG. 5, 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 the solid-state imaging device according to the embodiment of the present invention as described above, two pairs vertically adjacent to each other with the corner at the lower leftmost position of the element separation region 103 shown in FIG. 8A as a starting point at a distance of 0. The potential distribution of each position of the element separation region portion 13 in the pixel pair 12 of is shown in FIG. 8 (b). That is, the position of the maximum potential of the element separation region portion 13 is set to a position near the end portion of the element separation region portion 13 of the pixel pair 12.

The element separation region portion 13 has a long strip shape in a plane shape, and the position near both ends of the long strip shape is the position of the maximum potential.

A plurality of pixel pairs 12 are arranged adjacent to each other so that the longitudinal directions of the element separation region portions 13 coincide with each other on a plane. The element separation region portion 13 of one pixel pair 12 and the element separation region portion 13 of the pixel pair 12 vertically adjacent to the one pixel pair 12 are arranged in a straight line.

Since the potential distribution of the element separation region portion 13 is set as described above, as shown in FIG. 8A, light l is emitted from the microlens 11 of one pixel pair 12 toward the element separation region portion 13. Electrons e are generated by incident and photoelectric conversion. However, since the end portion of the element separation region portion 13 of the pixel pair 12 has the maximum potential, the electron e is directed toward the element separation region portion 13 of the other adjacent pixel pair 12 at the boundary between the pixel pairs 12. Cross talk (color mixing) can be suppressed without progressing (FIGS. 8 and 4).

The effect of the above maximum potential position will be explained as follows. At the maximum potential position, the electric field at this location becomes stronger. Therefore, the electron e generated in the element separation region portion 13 of the pixel pair 12 advances to the maximum potential position (strong electric field region) of the end portion of the element separation region portion 13 of the pixel pair 12 on its own side, and advances to the other side (adjacent). It does not invade the area of the pixel pair 12 on the side). As described above, the electron e does not move in the direction of the pixel pair 12 on the adjacent side, and the occurrence of crosstalk can be suppressed.

In the solid-state imaging device having the above configuration, in the ion implantation step of the element separation region portion 13, the dose amount at the time of ion implantation into the portion having the maximum potential is made smaller than the dose amount in other portions. It will be realized.

Specifically, in the first embodiment, as shown in FIG. 9A, it is assumed that the element separation region portion 13 is divided into a portion 13M having the maximum potential and a portion 13F other than that. Therefore, the resist pattern 20 (FIG. 9B) in which the opening 21 corresponding to the portion 13M having the maximum potential is formed, and the opening corresponding to the portion 13F which is the element separation region portion other than the portion having the maximum potential. Ion implantation is performed using the resist pattern 30 (FIG. 9 (c)) in which the portion 31 is formed. When ion implantation is performed using the resist pattern 20, the dose amount is smaller than that when ion implantation is performed using the resist pattern 30.

In the second embodiment, ions are implanted using the resist pattern 40 (FIG. 10) in which the opening 41 corresponding to the portion 13F, which is the element separation region portion other than the portion having the maximum potential, is formed to obtain the maximum potential. Ion implantation is not performed in the site 13M.

In the third embodiment, the area of the opening at the position corresponding to the portion 13M having the maximum potential is smaller than the area of the portion 13F other than the portion 13M having the maximum potential of the element separation region portion 13. Ion implantation is performed using the resist pattern.

In the first aspect of the third embodiment, the element separation region portion 13 has a long strip-like planar shape. At the position corresponding to the portion having the maximum potential, the width of the shape is made narrower than the slit 51 (opening) of the portion corresponding to the portion other than the portion having the maximum potential to realize an opening having a small area (FIG. 11). In this embodiment, the resist pattern 50 is used for ion implantation. The slit 51 of the resist pattern 50 is continuous with the slit 52, and the portion of the narrow slit 52 corresponds to the portion having the maximum potential.

In the second embodiment of the third embodiment, a plurality of openings 62 are formed as shown in FIG. 12 corresponding to the positions corresponding to the portions having the maximum potential, and the maximum potential of the element separation region portion 13 as a whole is formed. Ion implantation is performed using a resist pattern 60 that realizes an opening having an area smaller than the area of the portion 13F corresponding to the portion other than the portion.

The resist patterns 20 and 30 shown in the first embodiment of the present invention as described above, the resist pattern 40 shown in the second embodiment, and the resist patterns 50 and third shown in the first embodiment of the third embodiment. By performing ion injection using the resist pattern 60 shown in the embodiment, the position of the maximum potential of the element separation region portion 13 can be set to a position near the end portion of the element separation region portion 13. The resist patterns 20, 30, 40, 50, and 60 indicate parts of the resist pattern used in the ion implantation step of the solid-state image sensor, which correspond to one pixel pair.

11 Microlens 12 Pixel pair 12L First pixel 12R Second pixel 13 Element separation area 13F Part 13M Part 14 Flattening layer 15 Color filter 16 Peripheral light-shielding film 20, 30, 40, 50, 60 Resist pattern 21, 31, 41, 62 Openings 51, 52, 61 Slits

Claims (8)

One microlens and an image plane retardation pixel, which is a pixel pair including a pair of a first pixel and a second pixel arranged behind the one microlens, are arranged in the vertical direction in a plane. It is a solid-state image sensor that is arranged adjacent to each other in the horizontal direction.
In each pixel pair, an element separation region portion is provided in a boundary region where the first pixel and the second pixel are adjacent to each other.
In a solid-state imaging device in which the position of the maximum potential of the element separation region portion is set to a position near the end portion of the element separation region portion .
A solid-state imaging device, characterized in that a plurality of the pixel pairs are arranged adjacent to each other so that the longitudinal directions of the element separation regions coincide with each other on a plane . The element separation region portion has a long strip-like planar shape.
The solid-state image sensor according to claim 1, wherein the position near both ends of the long strip is the position of the maximum potential. In the method for manufacturing a solid-state image sensor according to claim 1 or 2 .
A method for manufacturing a solid-state imaging device, characterized in that, in the ion implantation step of the element separation region portion, the dose amount at the time of ion implantation into a portion having the maximum potential is smaller than the dose amount in other portions. Ion implantation is performed using a resist pattern in which an opening corresponding to a portion having the maximum potential is formed and a resist pattern in which an opening corresponding to the element separation region portion other than the portion having the maximum potential is formed. The method for manufacturing a solid-state image sensor according to claim 3 . The third aspect of claim 3 , wherein ions are implanted using a resist pattern in which an opening corresponding to the element separation region portion other than the portion having the maximum potential is formed, and ions are not implanted into the portion having the maximum potential. A method for manufacturing a solid-state image sensor. 3. The third aspect of the present invention is that ion implantation is performed at a position corresponding to a portion having the maximum potential by using a resist pattern having an opening having an area smaller than the area other than the portion having the maximum potential of the element separation region portion. The method for manufacturing a solid-state image sensor according to. The element separation region portion has a long strip-like planar shape.
The sixth aspect of claim 6 is characterized in that ions are implanted using a resist pattern in which both ends of the long strip-shaped slit are narrowed to realize a small area opening at a position corresponding to a portion having a maximum potential. Method for manufacturing a solid-state image sensor. The sixth aspect of claim 6 , wherein a plurality of openings are formed corresponding to the positions corresponding to the portions having the maximum potential, and ions are implanted using a resist pattern in which the openings having a small area as a whole are realized. Method for manufacturing a solid-state image sensor.

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