JP6194598B2 - Image pickup device and image pickup apparatus including image pickup device - Google Patents

Description

  The present invention relates to an imaging device and an imaging apparatus including the imaging device.

In a solid-state imaging device, in order to efficiently guide optical carriers to a photodiode, an impurity concentration peak (a potential barrier of optical carriers) is formed within a certain depth in a substrate (for example, known) , See Patent Document 1). In addition, in a solid-state imaging device, a device in which a potential barrier that separates adjacent pixels from each other is formed to the same depth in all pixels is known (for example, see Patent Document 2).
Patent Document 1 Japanese Patent Application Laid-Open No. 2005-347691 Patent Document 2 Japanese Patent Application Laid-Open No. 2011-124451

  When a potential barrier that separates adjacent pixels from each other is provided as in the solid-state imaging device described in Patent Document 2, crosstalk between pixels can be suppressed and deterioration of the degree of color mixing can be prevented. However, in the solid-state imaging device described in Patent Document 2, the potential barrier that separates adjacent pixels from each other is uniformly provided up to a deep position, and the spectral sensitivity of each pixel is increased using the optical carrier of the adjacent pixels. It is difficult to maximize.

  The imaging device according to the first aspect of the present invention includes a first conductive type first semiconductor layer, a second conductive type second semiconductor layer provided on an incident light incident side with respect to the first semiconductor layer, A plurality of semiconductor regions of the first conductivity type provided on the incident side with respect to the second semiconductor layer; a color filter provided corresponding to each of the plurality of semiconductor regions so as to transmit incident light; and a plurality of semiconductors The second semiconductor layer is provided in the depth direction in which incident light is incident so as to separate the regions from each other, and the depth of the impurity is higher than that of the second semiconductor layer, which has a different depth corresponding to the transmission wavelength band of the color filter. And a two-conductivity type pixel isolation region.

  Moreover, the imaging device in the 2nd aspect of this invention is equipped with said imaging device.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a figure which shows the elements on larger scale of the image pick-up element in the 1st Embodiment of this invention. It is a figure which shows the AA cross section of FIG. It is a figure which shows the BB cross section of FIG. It is a figure which shows the relationship between the substrate depth in the II part of FIG. 2, and the profile of impurity concentration. It is a figure which shows the plane separation area | region in the depth D1. It is a figure which shows the plane separation area | region in depth D2. It is a figure which shows the effective pixel area | region of the green color filter of the image pick-up element in the 1st Embodiment of this invention. It is a figure which shows the effective pixel area | region of the red color filter of the image pick-up element in the 1st Embodiment of this invention. It is a figure which shows the pixel sectional drawing of the image pick-up element in the 2nd Embodiment of this invention. It is a figure which shows the pixel sectional drawing of the image pick-up element in the 2nd Embodiment of this invention. It is a figure which shows the relationship between the substrate depth in the II-II part of FIG. 9, and the profile of impurity concentration. It is a figure which shows the elements on larger scale of the imaging device in the 3rd Embodiment of this invention, and an imaging device. It is sectional drawing of the single-lens reflex camera provided with the image pick-up element in the 4th Embodiment of this invention.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a diagram showing an image sensor 1 according to the first embodiment of the present invention. FIG. 1 also shows an enlarged view of the image sensor 1. The imaging element 1 has a plurality of pixels formed in a matrix. In this example, the shape of each pixel viewed from a direction perpendicular to the top surface on which a plurality of pixels are arranged is a square or a rectangle.

  In the image sensor 1 of this example, the unit groups 5 composed of a plurality of pixels are continuously arranged in the row direction and the column direction. The unit group 5 has a so-called Bayer arrangement composed of four pixels of two green pixels Gr, a blue pixel Bl, and a red pixel Re. That is, the blue pixel Bl is provided with four sides adjacent to the green pixel Gr. Similarly, the red pixel Re is provided with four sides adjacent to the green pixel Gr. The green pixel Gr is provided with two opposite sides adjacent to the blue pixel Bl, and the other two opposite sides adjacent to the red pixel Re. The green pixel Gr has a green color filter 202 and transmits light in the green wavelength band as the main component of incident light. Similarly, the blue pixel Bl has a blue color filter 201 and transmits light in a blue wavelength band as a main component. The red pixel Re has a red color filter 203 and transmits light in the red wavelength band as a main component.

  FIG. 2 is a view showing a cross section AA of FIG. In the cross section, the imaging device 1 includes a first conductivity type first semiconductor layer 10, a second conductivity type second semiconductor layer 20, a second conductivity type pixel isolation region 30, and a plurality of second conductivity type planar separations. A region 80, a plurality of first conductivity type semiconductor regions 100, and a color filter 200 are provided. The first conductivity type and the second conductivity type are conductivity types having different polarities. For example, one of the first conductivity type and the second conductivity type is P-type, and the other is N-type.

  Incident light enters the image sensor 1 from the color filter 200. Therefore, the incident side means the color filter 200 side with respect to the image sensor 1. Further, the depth means the depth in the light incident direction from the surface on the incident side of the second semiconductor layer 20 located closest to the incident side.

  The depth D1 in FIG. 2 is a depth between a depth Db in which light having a wavelength to be detected by the blue pixel Bl is absorbed and a depth Dg in which light having a wavelength to be detected by the green pixel Gr is absorbed. Indicates. Further, the depth D1 may be intermediate between the depth Db and the depth Dg. The depth Db is shallower than the depth Dg. The depth D2 in FIG. 2 is set between a depth Dg at which light having a wavelength to be detected by the green pixel Gr is absorbed and a depth Dr at which light having a wavelength to be detected by the red pixel Re is absorbed. The The depth D2 may be intermediate between the depth Dg and the depth Dr. The depth Dg is shallower than the depth Dr.

  The first semiconductor layer 10 of this example is an N-type semiconductor layer. The first semiconductor layer 10 may be a P-type semiconductor layer. Further, the first semiconductor layer 10 may be an N-type or P-type semiconductor substrate. More specifically, the first semiconductor layer 10 may be an N-type or P-type silicon substrate. In the first semiconductor layer 10, a second semiconductor layer 20, a pixel isolation region 30, a plurality of planar isolation regions 80, and a plurality of semiconductor regions 100 are formed.

  The second semiconductor layer 20 is provided on the incident light incident side with respect to the first semiconductor layer 10. It means the color filter 200 side with respect to the first semiconductor layer 10. In this example, the second semiconductor layer 20 is a P-type semiconductor layer. The second semiconductor layer 20 may be a P-type well. The second semiconductor layer 20 is formed by doping a dopant having a polarity opposite to that of the first semiconductor layer 10 from the surface of the first semiconductor layer 10 to the position of Dw. Note that Dw is deeper than D2. The second semiconductor layer 20 forms a PN junction together with a plurality of semiconductor regions 100 described later.

  The plurality of semiconductor regions 100 are provided on the incident side with respect to the second semiconductor layer 20. The plurality of semiconductor regions 100 are formed by doping a first conductivity type dopant from the surface of the second semiconductor layer 20. A plurality of semiconductor regions 100 are arranged in a planar direction parallel to the surface of the second semiconductor layer 20. In the AA cross section, the plurality of semiconductor regions 100 includes a semiconductor region 101 and a semiconductor region 102. In this example, the semiconductor region 101 and the semiconductor region 102 are N-type semiconductor regions, respectively. The semiconductor region 101 corresponds to the blue pixel Bl, and the semiconductor region 102 corresponds to the green pixel Gr.

  A plurality of semiconductor regions 100 are formed at positions where the N-type dopant is doped in the second semiconductor layer 20, and a PN junction is formed at a junction between the plurality of semiconductor regions 100 and the second semiconductor layer 20. Charges generated by photoelectrically converting incident light in the depletion layer in the PN junction are accelerated in the direction of the plurality of semiconductor regions 100 by the electric field of the depletion layer and accumulated in the plurality of semiconductor regions 100. Of the charges generated in the second semiconductor layer 20 that are not separated from the depletion layer by the pixel separation region 30 and the plurality of planar separation regions 80, the charge reaching the depletion layer is caused by the depletion layer. Accelerated in the direction of the plurality of semiconductor regions 100 and accumulated in the plurality of semiconductor regions 100.

  The depth at which the PN junction is formed may be determined according to the wavelength of light to be detected by each pixel. For example, when the first semiconductor layer 10 is a silicon substrate, since the absorption coefficient of the short wavelength is high at a shallow position in the depth direction, in the semiconductor region 101 corresponding to the blue pixel, the incident light is incident in the depth direction. A PN junction is provided near the shallow position. On the contrary, since the long wavelength absorption coefficient is high at a deep position in the depth direction, a PN junction is provided at a position deeper than the semiconductor region 101 in the semiconductor region 102 corresponding to the green pixel.

  In the AA cross section, the color filter 200 includes a blue color filter 201 and a green color filter 202. Each color filter 200 is provided corresponding to each of the plurality of semiconductor regions 100 so as to transmit a predetermined wavelength component of incident light. For example, the color filter 200 corresponding to the blue pixel transmits the wavelength component of the blue light. The second semiconductor layer 20 generates a charge corresponding to the light transmitted by each color filter 200 in a region below each color filter 200.

  The pixel isolation region 30 is provided extending in the depth direction in which incident light is incident on the second semiconductor layer 20 so as to separate the plurality of semiconductor regions 100 from each other. Further, the pixel isolation region 30 is provided along the boundary of each pixel shown in FIG. In the example of FIG. 2, the pixel isolation region 30 is provided extending to the depth D <b> 1 between the semiconductor region 101 and the semiconductor region 102.

  The pixel isolation region 30 is provided so as to isolate the semiconductor region 101 from the semiconductor region 102. Here, when the image pickup device 1 is viewed from above as shown in FIG. 1, the blue color filter 201 is adjacent to the green color filter 202 in the row direction and the column direction. Therefore, the pixel isolation region 30 is provided so as to surround a region above the depth D1 in the second semiconductor layer 20 located below the blue color filter 201 in the depth direction.

The pixel isolation region 30 has a higher impurity concentration than the second semiconductor layer 20. For example, when the second conductivity type of the second semiconductor layer 20 is P type, the pixel isolation region 30 is set to P ⁺ . When the first conductivity type is N-type and the second conductivity type is P-type, the P ⁺ region of the pixel isolation region 30 is a potential region having a high potential for electrons generated by photoelectric conversion in the semiconductor region 101. . Accordingly, the pixel isolation region 30 prevents electrons generated in the region of the second semiconductor layer 20 surrounded by the pixel isolation region 30 from diffusing and accumulating in the semiconductor region 102. Therefore, crosstalk between pixels can be prevented.

  The plurality of plane separation regions 80 include a plane separation region 50 (first region) and a plane separation region 60 (second region) provided at a position deeper than the plane separation region 50 in the depth direction. The plane separation region 50 is provided for a pixel having the shortest wavelength of light to be detected (in this example, the blue pixel Bl) among the plurality of pixels. Further, the plane separation region 50 is provided in the second semiconductor layer 20 at a depth D1 corresponding to the transmission wavelength band of the corresponding color filter 200 in the plane direction orthogonal to the depth direction. The depth is the same as the depth at which the pixel isolation region 30 is provided. The plane separation region 50 is formed in a region surrounded by the pixel separation region 30 in the plane at the depth D1.

The planar isolation region 50 has a higher impurity concentration than the second semiconductor layer 20. For example, when the second semiconductor layer 20 has a P-type impurity, the pixel isolation region 30 is a P ⁺ region. In this example, the first conductivity type is N type, and the second conductivity type is P type. For electrons generated by photoelectric conversion in the second semiconductor layer 20, the P ⁺ region of the planar separation region 50 is a high potential potential region. Therefore, the P ⁺ region of the planar separation region 50 is located below the blue color filter 201 of the second semiconductor layer 20, and electrons generated in a region shallower than the depth D 1 are diffused downward from the planar separation region 50. Disturb. In addition, the P ⁺ region of the planar separation region 50 prevents electrons generated in a region deeper than the depth D1 (that is, electrons generated by light other than blue) from diffusing into the semiconductor region 101. Therefore, the semiconductor region 101 can store only charges corresponding to the wavelength components corresponding to the blue color filter 201.

  The plane separation region 60 includes a pixel having the shortest wavelength of light to be detected (in this example, a blue pixel B1) and a pixel having the next shortest wavelength of light to be detected (in this example, a green pixel Gr). ) And. The plane separation region 60 is provided at a depth D2 corresponding to the longer wavelength band among the transmission wavelength bands of light to be detected by the corresponding pixels in the plane direction orthogonal to the depth direction in the second semiconductor layer 20. It is done. In this example, the plane separation region 60 is provided at a position corresponding to the wavelength band of light to be detected by the green pixel Gr.

Further, the planar isolation region 60 has an impurity concentration higher than that of the second semiconductor layer 20. In this example, the pixel separation region 30 is a P ⁺ region. Therefore, the P ⁺ region of the planar isolation region 60 prevents electrons generated in the region between the depths D1 and D2 of the second semiconductor layer 20 from diffusing in the direction of the first semiconductor layer 10. Further, electrons generated in a region deeper than the depth D <b> 2 of the second semiconductor layer 20 are prevented from reaching the semiconductor region 102.

  With the above configuration, the blue component transmitted through the blue color filter 201 is photoelectrically converted in the region surrounded by the pixel separation region 30 and the planar separation region 50 in the second semiconductor layer 20. Electrons generated in the region are accumulated in the semiconductor region 101. In addition, since electrons generated outside the region cannot reach the semiconductor region 101, the semiconductor region 101 stores only electrons generated in the region.

  Further, the green component transmitted through the green color filter 202 is photoelectrically converted in the region between the depths D1 and D2 in the second semiconductor layer 20. However, the wavelength band of the light transmitted through the blue color filter 201 has a certain extent around the blue wavelength. Therefore, light corresponding to the green wavelength band among the light transmitted through the blue color filter 201 is photoelectrically converted in a region sandwiched between the plane separation region 50 and the plane separation region 60. Therefore, the semiconductor region 102 is generated not only in the region below the green color filter 202 but also in the region below the blue color filter 201 (that is, the region sandwiched between the plane separation region 50 and the plane separation region 60). Electrons can also be stored. For this reason, the spectral sensitivity of the green pixel Gr can be improved.

  For example, when the blue color filter 201 has a transmission wavelength band that transmits a green wavelength component in addition to a blue wavelength component, the semiconductor region 102 is sandwiched between the planar separation region 50 and the planar separation region 60. Electrons generated in the selected region can also be accumulated, and the effective light receiving region of the green pixel Gr can be expanded. Also in this case, the spectral sensitivity of the green pixel Gr can be improved.

  FIG. 3 is a view showing a BB cross section of FIG. In the cross section, the imaging device 1 includes a first conductivity type first semiconductor layer 10, a second conductivity type second semiconductor layer 20, a second conductivity type plane separation region 60, and a plurality of first conductivity type semiconductor regions. 100 and a color filter 200.

  In the BB cross section, the plurality of semiconductor regions 100 includes a semiconductor region 102 and a semiconductor region 103. In this example, the semiconductor region 102 and the semiconductor region 103 are N-type semiconductor regions, respectively. The semiconductor region 102 corresponds to the green pixel Gr, and the semiconductor region 103 corresponds to the red pixel Re.

  In the semiconductor region 102 where the green light is incident, a PN junction may be provided near a position deeper than that of the blue light. In this example, a PN junction is provided at a position between the depth D1 and the depth D2 from the surface of the second semiconductor layer 20. In the semiconductor region 103 where the red light is incident, a PN junction may be provided near a position deeper than that in the case of the green light. In this example, a PN junction is provided at a position between the depth D2 and the depth Dw.

  In the BB cross section, the color filter 200 includes a green color filter 202 and a red color filter 203. The green color filter 202 is provided corresponding to the semiconductor region 102. The red color filter 203 is provided corresponding to the semiconductor region 103.

  The pixel isolation region 40 is provided extending in the depth direction in which incident light is incident on the second semiconductor layer 20 so as to separate the plurality of semiconductor regions 100 from each other. Further, the pixel separation region 40 is provided along the boundary of each pixel shown in FIG. In this example, the pixel isolation region 40 is provided to extend to the depth D2 between the semiconductor region 102 and the semiconductor region 103.

  As shown in FIGS. 2 and 3, the pixel separation regions 30 and 40 have different depths corresponding to the transmission wavelength band of the corresponding color filter 200. For example, the depth of the pixel separation regions 30 and 40 is reduced as the transmission wavelength band of the color filter 200 is shorter.

  Since the pixel separation regions 30 and 40 are provided between two pixels, two corresponding color filters 200 exist. Therefore, the depths of the pixel isolation regions 30 and 40 are determined with reference to the plurality of semiconductor regions 100 to which the short wavelength side color filter 200 is assigned among the plurality of adjacent semiconductor regions 100. In the example shown in FIGS. 2 and 3, the depth of the pixel separation region 30 is determined according to the transmission wavelength band of the blue color filter 201. Further, the depth of the pixel separation region 40 is determined according to the transmission wavelength band of the green color filter 202.

  The pixel isolation region 40 is provided so as to surround the semiconductor region 102 corresponding to a shorter wavelength band when the semiconductor region 102 and the semiconductor region 103 are adjacent to each other. Similar to the semiconductor region 101 and the semiconductor region 102, when the image pickup device 1 is viewed from above as shown in FIG. 1, the green color filter 202 is adjacent to the red color filter 203 in the row direction and the column direction. Accordingly, the pixel isolation region 40 is provided so as to surround a region above the depth D1 in the second semiconductor layer 20 located below the green color filter 202.

Similar to the pixel isolation region 30, the pixel isolation region 40 has a higher impurity concentration than the second semiconductor layer 20. In this example, since the first conductivity type is N type and the second conductivity type is P type, the P ⁺ region of the pixel isolation region 40 is high in potential for electrons generated by photoelectric conversion in the semiconductor region 102. It is a potential region. Therefore, the pixel isolation region 40 prevents electrons generated in the region of the second semiconductor layer 20 surrounded by the pixel isolation region 40 from diffusing into the semiconductor region 103. Therefore, crosstalk between pixels can be prevented.

  The plane separation region 60 is provided at a depth D2 corresponding to the transmission wavelength band of the corresponding color filter 200 in the plane direction orthogonal to the depth direction in the second semiconductor layer 20. The depth is the same as the depth at which the pixel isolation region 40 is provided. Further, the plane separation region 60 is formed in a region surrounded by the pixel separation region 40 in the plane at the depth D2.

  As described above, the plane separation region 60 includes a pixel having the shortest wavelength of light to be detected (in this example, the blue pixel B1) and a pixel having the next shortest wavelength of light to be detected (this book). In the example, it is provided for the green pixel Gr). Accordingly, the plane separation region 60 is not provided for the red pixel Re. The planar separation region 60 is provided at a position of depth D2 in all regions other than the region corresponding to the semiconductor region 103.

The planar isolation region 60 has a higher impurity concentration than the second semiconductor layer 20. In this example, the second semiconductor layer 20 is a P layer, and the pixel isolation region 40 is a P ⁺ region. In this example, since the first conductivity type is N type and the second conductivity type is P type, for the electrons generated in the second semiconductor layer 20, the P ⁺ regions of the pixel isolation region 40 and the plane isolation region 60. Is a potential region having a high potential. Therefore, the electrons generated in the second semiconductor layer 20 below the green color filter 202 and shallower than the depth D <b> 2 are prevented from diffusing downward from the planar separation region 60. Therefore, the semiconductor region 102 can accumulate only charges corresponding to the wavelength component corresponding to the green color filter 202 at a position deeper than the depth D1 and shallower than the depth D2.

  With the above configuration, the green component transmitted through the green color filter 202 is photoelectrically converted in the region surrounded by the pixel separation region 40 and the plane separation region 60 in the second semiconductor layer 20. Electrons generated in the region are accumulated in the semiconductor region 102. In addition, since electrons generated outside the region cannot reach the semiconductor region 102, the semiconductor region 102 stores only electrons generated in the region.

  The red component transmitted through the red color filter 203 is photoelectrically converted in the region between the depths D2 and Dw in the second semiconductor layer 20. However, the semiconductor region 103 can accumulate not only the region below the red color filter 203 but also electrons generated in the region below the blue color filter 201 and the green color filter 202. For example, when the blue color filter 201 and the green color filter 202 have a transmission wavelength band that further transmits a red wavelength component, the semiconductor region 103 is a region below the blue color filter 201 and the green color filter 202 and has a red color. Electrons generated by light of wavelength components can also be accumulated, and the effective light receiving area of the red pixel Re can be expanded. For this reason, the spectral sensitivity of the red pixel Re can be improved.

  According to the imaging device 1 shown in FIGS. 2 and 3, it is possible to improve the light receiving sensitivity of the green pixel Gr and the red pixel Re while preventing crosstalk between the pixels. Further, even if the pixels are miniaturized, unnecessary charge crosstalk from adjacent pixels can be suppressed, and color mixing can be suppressed.

  FIG. 4 is a diagram showing the relationship between the substrate depth and the impurity concentration profile in the II portion of FIG. The impurity concentration is the sum of the first conductivity type (N-type in this example) and the second conductivity type (P-type in this example). The direction in which incident light is incident is defined as the horizontal axis (depth). The position where the incident light enters the second semiconductor layer 20 after passing through the color filter 200 is defined as depth 0.

  In the second semiconductor layer 20, the concentration of the P-type impurity is higher than that of the N-type impurity. The concentration of the P-type impurity is a constant concentration in the depth direction. However, the P-type impurity concentration has a maximum value in the plane separation region 50 of D1 in the substrate depth direction. Further, the P-type impurity concentration similarly becomes the maximum value in the plane separation region 60 of D2 in the substrate depth direction.

  The second semiconductor layer 20 is joined to the first semiconductor layer 10 at the position Dw in the depth direction. That is, a depletion layer is formed in the vicinity of Dw in the substrate depth direction. The P-type and N-type impurity concentrations are minimum values near Dw in the substrate depth direction. Note that since the region deeper than the depth Dw is the first semiconductor layer 10, the concentration of the N-type impurity is higher than that of the P-type impurity. In a region deeper than the depth Dw, the concentration of the N-type impurity is constant.

  FIG. 5 is a diagram showing the plane separation region 50 (first region) at the depth D1. The first region is provided discretely for each of the corresponding semiconductor regions 100. In this example, the planar separation region 50 is provided only in a region corresponding to the semiconductor region 101 (blue color filter 201) at the position of the depth D1 of the second semiconductor layer 20.

  FIG. 6 is a diagram illustrating the plane separation region 60 (second region) at the depth D2. The second region may be provided so as to have an opening for each of the corresponding semiconductor regions 100. For example, the planar separation region 60 is provided in a region other than the region corresponding to the semiconductor region 103 (red color filter 203) at the position of the depth D2 of the second semiconductor layer 20.

  FIG. 7 is a diagram illustrating the effective pixel region 301 of the green color filter 202 of the image sensor 1 according to the first embodiment of the present invention. When the sensitivity region of the semiconductor region corresponding to a certain color filter is extended to a region immediately below another color filter in addition to the region immediately below the color filter, the expanded sensitivity region is set as an effective pixel region.

  The semiconductor region 102 immediately below the green color filter 202 has green light transmitted through the blue color filter 201 adjacent to the green color filter 202 in addition to electrons generated by the light of the green wavelength component transmitted through the green color filter 202. Electrons generated by light of wavelength components can also be accumulated.

  On the other hand, the semiconductor region 102 immediately below the green color filter 202 and the semiconductor region 103 immediately below the red color filter 203 are separated by the pixel separation region 40 and the planar separation region 60. Therefore, the semiconductor region 102 immediately below the green color filter 202 cannot accumulate electrons generated by the light of the green wavelength component that has passed through the red color filter 203 adjacent to the green color filter 202.

  Therefore, the sensitivity region of the green color filter 202 is extended to the blue color filter 201. The expanded area may have a triangular shape including one side of the blue color filter 201 adjacent to the green color filter 202 and the center of the blue color filter 201. However, the shape of the expanded region is not necessarily limited to the triangular shape.

  FIG. 8 is a diagram illustrating the effective pixel region 302 of the red color filter 203 of the image sensor 1 according to the first embodiment of the present invention. The semiconductor region 103 immediately below the red color filter 203 has a red color transmitted through the green color filter 202 adjacent to the red color filter 203 in addition to the electrons generated by the light of the red wavelength component transmitted through the red color filter 203. Electrons generated by light of wavelength components can also be accumulated.

  Since the blue color filter 201 does not pass the red wavelength band, there are no electrons generated by light of the red wavelength component. In addition, since the blue color filter 201 is separated from the red color filter 203 by the pixel separation region 30 and the plane separation region 50, the semiconductor region 103 immediately below the red color filter 203 is not included in the red color filter 203. It is not possible to store electrons generated by the light of the red wavelength component that has passed through the blue color filter 201 positioned in an opposite manner.

  Therefore, the sensitivity region of the red color filter 203 is extended to the green color filter 202 adjacent to the red color filter 203 on the left, right, upper, and lower sides. One of the expanded regions may have a triangular shape including one side of the green color filter 202 adjacent to the red color filter 203 and the center of the green color filter 202. However, one shape of the expanded area is not necessarily limited to a triangular shape.

  FIG. 9 is a diagram showing an AA cross section of the image sensor 2 according to the second embodiment of the present invention. The image sensor 2 has a plurality of pixels in the same manner as the image sensor 1 shown in FIG. Further, the position of the AA cross section in FIG. 9 is the same as the AA cross section of the image sensor 1. The image sensor 2 further includes a plane separation region 70 (third region) in addition to the configuration of the image sensor 1. Other configurations are the same as those of the image sensor 1.

The plane separation region 70 is provided at a depth D3 corresponding to the transmission wavelength band on the longest wavelength side among the transmission wavelength bands of the plurality of color filters 200. In this example, the depth D3 at which the planar separation region 70 is provided is deeper than the depth Dr at which the second semiconductor layer 20 absorbs light in the red wavelength band and shallower than the depth Dw. The plane separation region 70 is provided on a uniform surface at the depth D3. The uniform surface means that it does not have an opening like the plane separation region 60 shown in FIG. 6 and is provided for all of a plurality of pixels. The planar isolation region 70 has a higher impurity concentration than the second semiconductor layer 20. In this example, the second semiconductor layer 20 is a P-type semiconductor layer. Therefore, the plane separation region 70 is a P ⁺ region, like the plane separation region 50 and the plane separation region 60.

FIG. 10 is a diagram showing a BB cross section of the image sensor 2 according to the second embodiment of the present invention. The position of the BB cross section in FIG. 10 is the same as the BB cross section of the image sensor 1. The plane separation region 70 is provided on a uniform surface at the depth D3. For electrons generated in response to light in the red wavelength band, the P ⁺ region of the plane isolation region 70 is a potential region having a high potential, and therefore the plane isolation region 70 has a depth D3 in the second semiconductor layer 20. The electrons generated in the shallow region are prevented from diffusing into the first semiconductor layer 10. Therefore, the spectral sensitivity characteristic of the red pixel Re is improved.

  FIG. 11 is a diagram showing the relationship between the substrate depth and the impurity concentration profile in the II-II portion of FIG. The difference from the first embodiment is that the impurity concentration of the second semiconductor layer 20 becomes the maximum value even in the plane separation region 70 of D3 in the substrate depth direction.

  FIG. 12 is a diagram showing an image sensor 3 according to the third embodiment of the present invention. FIG. 12 also shows an enlarged view of the image pickup device 3. In the image pickup device 3, unit groups 6 composed of a plurality of pixels are continuously arranged in the row direction and the column direction. The unit group 6 has a so-called Bayer arrangement composed of four pixels of a green pixel Gr, a yellow pixel Ye, a cyan pixel Cy, and a magenta pixel Ma. The yellow pixel Ye has a yellow color filter 214 and receives light in the red wavelength band and the green wavelength band. The cyan pixel Cy has a cyan color filter 213 and receives light in the green wavelength band and the blue wavelength band. The green pixel Gr has a green color filter 212 and receives light in the green wavelength band. Further, the magenta color pixel Ma has a magenta color filter 211 and receives light in the blue wavelength band and the red wavelength band.

  For example, since the cyan color filter 213 transmits light in the blue wavelength band and the green wavelength band, the cyan color filter 213 is used as a blue pixel, and the yellow color filter 214 adjacent to the cyan color filter 213 is used. Charges generated by receiving the green wavelength band of the cyan color filter 213 can be accumulated. Therefore, the effective pixel area of the yellow color filter 214 can be expanded.

  FIG. 13 is a cross-sectional view of a single-lens reflex camera 400 including the imaging device 1 according to the fourth embodiment. The single-lens reflex camera 400 includes a lens unit 500 and a camera body 600. A lens unit 500 is attached to the camera body 600. The lens unit 500 includes an optical system arranged along the optical axis 410 in the lens barrel, and guides an incident subject light flux to the image sensor 1 of the camera body 600.

  The camera body 600 includes a main mirror 672 and a sub mirror 674 behind a body mount 660 coupled to the lens mount 550. The main mirror 672 is pivotally supported between an oblique position obliquely provided to the subject light beam incident from the lens unit 500 and a retracted position retracted from the subject light beam. The sub mirror 674 is pivotally supported with respect to the main mirror 672 so as to be rotatable.

  When the main mirror 672 is in the oblique position, most of the subject light beam incident through the lens unit 500 is reflected by the main mirror 672 and guided to the focus plate 652. The focus plate 652 is arranged at a position conjugate with the light receiving surface of the image sensor 1 and visualizes the subject image formed by the optical system of the lens unit 500. The subject image formed on the focus plate 652 is observed from the viewfinder 650 through the pentaprism 654 and the viewfinder optical system 656. Part of the subject light beam incident on the main mirror 672 at the oblique position passes through the half mirror region of the main mirror 672 and enters the sub mirror 674. The sub mirror 674 reflects a part of the light beam incident from the half mirror region toward the focusing optical system 680. The focusing optical system 680 guides a part of the incident light beam to the focus detection sensor 682.

  The focus plate 652, the pentaprism 654, the main mirror 672, and the sub mirror 674 are supported by a mirror box 670 as a structure. The mirror box 670 is attached to the image sensor 1. When the main mirror 672 and the sub mirror 674 are retracted to the retracted position and the front curtain and the rear curtain of the shutter unit 640 are in the open state, the subject luminous flux that passes through the lens unit 500 reaches the light receiving surface of the image sensor 1.

  A body substrate 620 and a rear display unit 634 are sequentially disposed behind the image sensor 1. A rear display unit 634 employing a liquid crystal panel or the like appears on the rear surface of the camera body 600. Electronic circuits such as a CPU 622 and an image processing ASIC 624 are mounted on the body substrate 620. The output of the image sensor 1 is delivered to the image processing ASIC 624 via a flexible substrate.

  In the above-described embodiment, the single-lens reflex camera 400 has been described as an example of the imaging apparatus. However, the camera body 600 may be regarded as an imaging apparatus. The imaging device is not limited to the interchangeable lens camera including the mirror unit, but may be a interchangeable lens camera that does not include the mirror unit or a lens-integrated camera regardless of the presence or absence of the mirror unit.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Image pick-up element, 2 Image pick-up element, 3 Image pick-up element, 5 unit group, 6 unit group, 10 1st semiconductor layer, 20 2nd semiconductor layer, 30 pixel separation area, 40 pixel separation area, 50 plane separation area, 60 plane separation Area, 70 plane separation area, 80 plural plane separation areas, 100 plural semiconductor areas, 101 semiconductor areas, 102 semiconductor areas, 103 semiconductor areas, 200 color filters, 201 blue color filters, 202 green color filters, 203 red color filters 211 magenta color filter, 212 green color filter, 213 cyan color filter, 214 yellow color filter, 400 single-lens reflex camera, 410 optical axis, 500 lens unit, 550 lens mount, 600 camera body, 620 Body substrate, 622 CPU, 624 Image processing ASIC, 634 Rear display, 640 Shutter unit, 650 Viewfinder, 652 Focus plate, 654 Pentaprism, 656 Viewfinder optical system, 660 Body mount, 670 Mirror box, 672 Main mirror, 674 Submirror , 680 focusing optical system, 682 focus detection sensor

Claims (5)

A first semiconductor layer of a first conductivity type;
A second conductive type second semiconductor layer provided on the incident light incident side with respect to the first semiconductor layer;
A plurality of semiconductor regions of the first conductivity type provided on the incident side with respect to the second semiconductor layer;
A color filter provided corresponding to each of the plurality of semiconductor regions so as to transmit the incident light;
The second semiconductor provided in the depth direction in which the incident light is incident on the second semiconductor layer so as to separate the plurality of semiconductor regions from each other, and having different depths corresponding to a transmission wavelength band of the color filter A pixel isolation region of the second conductivity type having a higher impurity concentration than the layer;
It said provided corresponding to the transmission wavelength band in a planar direction orthogonal to the depth direction in the second semiconductor layer, and a flat surface separating regions of high the impurity concentration than the second semiconductor layer and the second conductivity type With
The plane separation region has a first plane separation region and a second plane separation region provided at a position deeper than the first plane separation region in the depth direction,
The first plane isolation region and the second plane isolation region are provided in contact with an end portion of the pixel isolation region so as to surround the semiconductor region ,
The first plane separation region is discretely provided for each of the semiconductor regions provided with a color filter having a transmission wavelength band on the shortest wavelength side, and has a depth corresponding to the transmission wavelength band on the shortest wavelength side. Have
The second plane separation region is provided so as to have an opening with respect to each of the semiconductor regions in which the color filter of the transmission wavelength band on the longest wavelength side is provided, and has the shortest wavelength next to the shortest wavelength side Has a depth corresponding to the transmission wavelength band,
The closer the transmission wavelength band of the color filter provided correspondingly is to the shorter wavelength side, the shallower the depth of the pixel separation region,
The pixel separation region is an image pickup device in which a depth is determined based on a semiconductor region to which the color filter on the short wavelength side is assigned among the plurality of adjacent semiconductor regions . The planar isolation region, the imaging device according to claim 1 having a third planar isolation region of uniform surface provided in correspondence with the transmission wavelength band of the longest wavelength side. The color filters are red, green, image pickup device according to claim 1 or 2 including a blue filter. The color filters are cyan, magenta, the image pickup device according to claim 1 or 2 comprising a yellow filter. The imaging device provided with the image pick-up element of any one of Claim 1 to 4 .

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