JP2006019588A - Solid-state imaging apparatus and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus for correcting a chromatic aberration of every chromatic signal of a color filter, and to provide its manufacturing method. <P>SOLUTION: The solid-state imaging apparatus has a color filter over each photosensor as a light receiving part, and a boundary shape of a medium having a difference refraction factor over the photo sensor differs for every pixel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device that corrects chromatic aberration for each color signal of a color filter and a manufacturing method thereof.

  As the solid-state imaging device, a single-plate color CCD solid-state imaging device, a color CMOS solid-state imaging device, and the like are widely known. FIG. 11 shows an example of a schematic cross section of a conventional structure of a single-plate color CCD solid-state imaging device. In this single-plate color CCD solid-state imaging device 101, for example, the light receiving portions 103 serving as pixels are arranged in a matrix in the imaging region of the silicon semiconductor substrate 102, and the vertical transfer register 7 is formed corresponding to each light receiving portion row. Further, a color filter 112 and an on-chip microlens (hereinafter referred to as a microlens) 113 are formed on the imaging region via a silicon oxide layer 110 and a silicon nitride layer 111. The vertical transfer register 107 is configured by forming a transfer electrode 106 made of, for example, polycrystalline silicon through a gate insulating film 105 on a transfer channel region 104 formed on the surface of the substrate 102. On the surface of the substrate 102, a light shielding film 9 made of, for example, aluminum (Al) or tungsten (W) is formed in a region including the vertical transfer register 107 other than the light receiving portion 103 via an interlayer insulating film 108, and further silicon oxide A layer 110 and a silicon nitride layer 111 are formed. A color filter 112 made of each color filter component is formed on the silicon nitride layer 111, and a microlens 113 corresponding to each light receiving unit 103 is formed on the color filter 112.

  In the case of a single-plate color solid-state imaging device, the color filter 112 is formed on-chip, and the types are roughly classified into a primary color system and a complementary color system. The primary color system has good color reproducibility, and the complementary color system has a high transmittance of the color filter and is advantageous for sensitivity. The primary color filter and the complementary color filter are properly used according to the purpose. For example, the primary color filter 112 has a red (R) filter component 112R, a green (G) filter component 112G, and a blue (B) filter component 112B (not shown). Further, there are various color arrangements of the filter 112. Typical examples of the primary color filter arrangement include G stripe RB line sequential, G checkered RB line sequential (Bayer arrangement), RGB vertical stripe, and the like. . On the other hand, the complementary color filter arrangement includes Ye / Cy / Mg / G color difference line sequential, Ye / G / Cy vertical stripes, W / Ye / Cy vertical stripes, and the like. Regardless of which color arrangement is adopted, in order to finally perform color separation into R / G / B, at least three colors are required, and generally one pixel is constituted by one color.

  FIG. 12 shows the average refractive index of the medium in each layer above the photosensor in the representative wavelength regions of blue, green, and red of the solid-state imaging device. The refractive index of each medium varies depending on the wavelength of light, and the refractive index decreases as the wavelength increases, except for the color filter. Here, the solid-state imaging device is usually formed in the same structure regardless of the wavelength length of the pixel colors such as blue (B), green (G), and red (R). Therefore, due to the influence of the difference in refractive index due to the wavelength of light, as shown in FIG. 13A, at the center of the imaging region, the light collection depth position on the photosensor is different depending on the difference between the RGB color signals LR, LG, LB. It changes in the order of LR, LG, LB, and so-called chromatic aberration occurs. Further, considering the pixels around the solid-state imaging device at this time, as shown in FIG. 13b, the red signal LR is caused by the deviation of the condensing position in the lateral direction above the photosensor due to the difference between the RGB color signals LR, LG, LB. , LG, and LB in this order. If such a color shift occurs for each color signal, the sensitivity decreases from the center to the periphery of the imaging area, and so-called shading differs for each color signal, so each of the blue, green, and red signals around the imaging area. The balance (white balance) is lost and the color changes.

On the other hand, as a prior art of the present invention, Patent Document 1 discloses that the refraction of incident light when passing through a microlens differs depending on the wavelength of light, and the focal position of each color light of red, green, and blue is shifted for each color. In order to improve sensitivity variations and color balance variations, a solid-state imaging device has been proposed which is configured to have different color filter thicknesses so that the focal positions of the respective color lights are aligned.
JP 2002-94037 A

  By the way, in recent years, the surface area of the photosensor has been further reduced due to the miniaturization of the pixel size, and the influence of the lateral misalignment of the light collection as described above has increased. Therefore, there is a demand for a structure that does not cause so-called chromatic aberration, in which the condensing position of each color signal is shifted due to the wavelength dependence of the refractive index of light.

  In view of the above, the present invention provides a solid-state imaging device that corrects chromatic aberration for each color signal of a color filter and a manufacturing method thereof.

  The solid-state imaging device of the present invention is a solid-state imaging device including a color filter above each photosensor serving as a light receiving unit, and the boundary surface shape of a medium having a refractive index difference above each photosensor is in accordance with each color signal. It is different for each pixel.

  The solid-state imaging device of the present invention is a solid-state imaging device including a color filter above each photosensor serving as a light receiving unit, and the refractive index of the medium formed above the photosensor is an upper medium <lower medium, A medium boundary shape of a pixel having a large refractive index difference in a wavelength range corresponding to the color of each pixel is formed in a convex shape, and a medium boundary shape of a pixel having a small refractive index difference is formed in a concave shape. In this configuration, the medium boundary shape includes a combination of a convex shape and a concave shape, or a combination of a convex shape, a concave shape, and a flat shape according to a pixel having a difference in refractive index.

  The solid-state imaging device of the present invention is a solid-state imaging device including a color filter above each photosensor serving as a light receiving unit, and the refractive index of the medium formed above the photosensor is an upper medium <lower medium, The medium boundary shape is a convex shape, and the curvature of the convex shape increases as the refractive index difference in the wavelength range corresponding to the color of each pixel increases. In this configuration, the medium boundary shape includes a combination of all convex shapes according to the difference in refractive index, or a combination of a convex shape and a flat shape.

  The solid-state imaging device of the present invention is a solid-state imaging device including a color filter above each photosensor serving as a light receiving unit, and when the refractive index of the medium formed above the photosensor is higher medium> lower medium, A medium boundary shape of a pixel having a large refractive index difference in a wavelength range corresponding to the color of the pixel is formed in a concave shape, and a medium boundary shape of a pixel having a small refractive index difference is formed in a convex shape. In this configuration, the medium boundary shape includes a combination of a convex shape and a concave shape, or a combination of a convex shape, a concave shape, and a flat shape according to a pixel having a difference in refractive index.

  The solid-state imaging device of the present invention is a solid-state imaging device including a color filter above each photosensor serving as a light receiving unit, and when the refractive index of the medium formed above the photosensor is higher medium> lower medium, The boundary shape is a concave shape, and the curvature of the concave shape increases as the refractive index difference in the wavelength range corresponding to the color of each pixel increases. In this configuration, the medium boundary shape includes a combination of all concave shapes according to the difference in refractive index, or a combination of a concave shape and a flat shape.

  A manufacturing method of a solid-state imaging device according to the present invention is a manufacturing method of a solid-state imaging device including a color filter composed of a plurality of color filter components, which is a lower medium layer above a photosensor of each light receiving unit. A step of forming a first color filter component having a flat upper surface, and a second surface so that the upper surface of a portion other than the first color filter component has a concave shape on the entire surface including the first color filter component. Forming the second color filter material film, patterning the second color filter material film by a photolithography method to form a second color filter component having a concave upper surface, and a third color filter material Forming a film and patterning it by a photolithography method to form a third color filter; and heat reflowing the upper surface of the third color filter component Forming a shape, characterized by having a step of forming the micro lenses is the upper medium layer on each color filter.

  The method for manufacturing a solid-state imaging device according to the present invention is a method for manufacturing a solid-state imaging device including a color filter including a plurality of filter components above a photosensor of each light receiving unit, and includes a first pixel on the lower medium layer. Forming a convex portion in a portion to be, forming a resist layer having an opening in a portion to be the second pixel of the lower medium layer, performing isotropic etching through the opening, A step of forming a concave portion in the side medium layer, a step of laminating an upper medium layer having a refractive index larger than that of the lower medium layer after removing the resist layer, and each color filter component and a micro on the upper medium layer. It has the process of forming a lens, It is characterized by the above-mentioned.

  In the solid-state imaging device according to the present invention, the condensing position of incident light of each color on the photosensor is made different for each pixel by changing the shape of the boundary surface of the medium having a refractive index difference above the photosensor in accordance with each color signal. Can be aligned.

  In the solid-state imaging device of the present invention, when the refractive index of the medium formed above the photosensor is an upper medium <lower medium, the medium boundary shape of the pixel having a large refractive index difference in the wavelength range corresponding to the color of each pixel By forming a convex shape, the condensing position of incident light is shifted upward by the convex lens effect. Further, by forming the medium boundary shape of the pixel having a small refractive index difference into a concave shape, the condensing position of incident light is shifted downward by the concave lens effect. Therefore, the condensing position of the incident light of each color on each photosensor can be made uniform.

  In the solid-state imaging device of the present invention, when the refractive index of the medium formed above the photosensor is an upper medium <lower medium, a pixel having a larger refractive index difference in a wavelength range corresponding to the color of each pixel has a convex shape. By increasing the curvature, the condensing position of incident light of each color is controlled by the convex lens effect having different curvatures, and the condensing position of incident light of each color on the photosensor can be made uniform.

  In the solid-state imaging device of the present invention, when the refractive index of the medium formed above the photosensor is upper medium> lower medium, the medium boundary shape of the pixel having a large refractive index difference in the wavelength range corresponding to the color of each pixel is obtained. By forming the concave shape, the condensing position of the incident light is shifted to be shallower by the convex lens effect. By forming the medium boundary shape of the pixel having a small refractive index difference into a convex shape, the condensing position of the incident light is shifted deeper by the concave lens effect. Therefore, the condensing position of the incident light of each color on the photosensor can be made uniform.

  In the solid-state imaging device of the present invention, when the refractive index of the medium formed above the photosensor is upper medium> lower medium, the curvature of the concave shape increases as the refractive index difference in the wavelength range corresponding to the color of each pixel increases. By increasing the value, the condensing position of incident light of each color on the photosensor can be made uniform by the convex lens effect having different curvatures.

  In the method for manufacturing a solid-state imaging device according to the present invention, the shape of the color filter that is the lower medium layer is formed in an uneven shape for each color signal, and the microlens that is the upper medium layer is formed. A concave-convex lens can be selectively formed on the boundary surface between them.

  In the method for manufacturing a solid-state imaging device according to the present invention, the concave / convex lens can be selectively formed on the boundary surface between the upper medium layer and the lower medium layer.

  According to the solid-state imaging device of the present invention, the chromatic aberration of the incident light from the on-chip microlens can be removed by changing the shape of the boundary surface of the medium having a refractive index difference for each pixel, and to the photosensor. It is possible to eliminate the deviation of the light collecting position. As a result, there is no condensing shift in the peripheral pixels, and there is no difference in shading for each color signal, so that no white balance shift occurs, and color change around the chip can be eliminated.

  According to the solid-state imaging device of the present invention, when the refractive index of the medium formed above the photosensor is the upper medium <the lower medium, the pixel medium having a large refractive index difference in the wavelength range corresponding to the color of each pixel. Since the boundary shape is formed in a convex shape and the medium boundary shape of the pixel having a small refractive index difference is formed in a concave shape, the irregular shape on the boundary surface of the medium having a refractive index difference is changed for each pixel. The chromatic aberration of the incident light from the chip microlens can be removed, and the deviation of the light collection position on the photosensor can be eliminated. As a result, there is no condensing shift in the peripheral pixels, and there is no difference in shading for each color signal, so that no white balance shift occurs, and color change around the chip can be eliminated.

  According to the solid-state imaging device of the present invention, the solid-state imaging device includes a color filter above each photosensor serving as a light receiving unit, and the refractive index of the medium formed above the photosensor has an upper medium <lower medium. In this case, the medium boundary shape is a convex shape, and the curvature of the convex shape increases as the refractive index difference increases in the wavelength range corresponding to the color of each pixel. By changing for each pixel, the chromatic aberration of the incident light from the on-chip microlens can be removed, and the deviation of the condensing position on the photosensor can be eliminated. As a result, there is no condensing shift in the peripheral pixels, and there is no difference in shading for each color signal, so that no white balance shift occurs, and color change around the chip can be eliminated.

  According to the solid-state imaging device of the present invention, the solid-state imaging device includes a color filter above each photosensor serving as a light receiving unit, and the refractive index of the medium formed above the photosensor is such that the upper medium> the lower medium. The medium boundary shape of a pixel having a large refractive index difference in the wavelength range corresponding to the color of each pixel is formed in a concave shape, and the medium boundary shape of a pixel having a small refractive index difference is formed in a convex shape. By changing the concavo-convex shape of the boundary surface of a certain medium for each pixel, the chromatic aberration of the incident light from the on-chip microlens can be removed, and the deviation of the condensing position on the photosensor can be eliminated. As a result, there is no condensing shift in the peripheral pixels, and there is no difference in shading for each color signal, so that no white balance shift occurs, and color change around the chip can be eliminated.

  According to the solid-state imaging device of the present invention, the solid-state imaging device includes a color filter above each photosensor serving as a light receiving unit, and the refractive index of the medium formed above the photosensor is such that the upper medium> the lower medium. The boundary shape of the medium is a concave shape, and the curvature of the concave shape increases as the refractive index difference in the wavelength range corresponding to the color of each pixel increases. By changing for each pixel, the chromatic aberration of the incident light from the on-chip microlens can be removed, and the deviation of the condensing position on the photosensor can be eliminated. As a result, there is no condensing shift in the peripheral pixels, and there is no difference in shading for each color signal, so that no white balance shift occurs, and color change around the chip can be eliminated.

  According to the method for manufacturing a solid-state imaging device of the present invention, the shape of the color filter that is the lower medium layer is formed in an uneven shape to form the microlens that is the upper medium layer. An uneven lens can be formed on the boundary surface according to the color signal. Therefore, it is possible to manufacture a solid-state imaging device in which no white balance deviation occurs due to the difference in shading for each color signal.

  According to the method for manufacturing a solid-state imaging device of the present invention, an uneven lens can be formed on the boundary surface between the upper medium layer and the lower medium layer according to each pixel. Therefore, it is possible to manufacture a solid-state imaging device in which no white balance deviation occurs due to the difference in shading for each color signal.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a single-plate color CCD solid-state image sensor applied to a solid-state image sensor according to the present invention.
The CCD solid-state imaging device 1 according to the present embodiment includes pixels arranged in a matrix in an imaging region of a semiconductor substrate, for example, a silicon semiconductor substrate (for example, a so-called epitaxial substrate obtained by growing an epitaxial layer on a semiconductor substrate) 2. Are formed, and vertical transfer registers 7 are formed corresponding to the three rows of the light receiving portions, and the color filter 12 is formed on the imaging region via the silicon oxide layer 10 and the silicon nitride layer 11. On-chip microlenses 13 arranged in an array are formed thereon. Each of the microlenses 13 is formed in an array at a position where light incident on the effective imaging region is condensed on each light receiving unit.

  The vertical transfer register 7 is configured by forming a transfer electrode 6 made of, for example, polycrystalline silicon via a gate insulating film 5 on a transfer channel region 4 formed on the substrate surface. On the substrate surface, an interlayer insulating film 8, a light shielding film 9 having an opening 9A in the light receiving portion 3, and a silicon oxide layer 10, a silicon nitride layer 11, and the like are further formed. As the color filter 12, a primary color filter composed of a red filter component 12R, a green filter component 12G, and a blue filter component 12B is formed in this example. In such a solid-state imaging device 1, in order to improve shading characteristics due to oblique light around the effective imaging region 15, the microlens 13 and the color filter components 12 </ b> R and 12 </ b> G are moved from the center of the effective imaging region 15 toward the periphery. , 12B is shifted from the center of the light receiving unit 3 toward the center of the effective imaging region, so-called exit pupil correction is performed.

Here, the refractive index of each medium constituting the upper layer of the light receiving unit 3 will be described. The refractive index relationship of each medium is microlens <color filter, color filter <silicon nitride, silicon nitride> silicon oxide, and the refractive index difference in each wavelength region of blue, green, and red is as shown in FIG. .
As shown in FIG. 2, at each RGB wavelength, the refractive index difference is caused by the difference in medium between the microlens and color filter constituting the solid-state imaging device, between the color filter and silicon nitride, and between silicon nitride and silicon oxide. Has occurred.
In this example, the refractive index difference between the microlens and the color filter is as follows: refractive index difference −0.02 when the blue (B) wavelength is 400 to 515 nm, and refractive index difference −0. When the red (R) wavelength is 570 to 650 nm, the refractive index difference is −0.18.
Next, the refractive index difference between the color filter and the silicon nitride layer is such that the refractive index difference is −0.44 when the blue (B) wavelength is 400 to 515 nm, and the refractive index difference is −0.37 when the green (G) wavelength is 490 to 590 nm. When the red (R) wavelength is 570 to 650 nm, the refractive index difference is −0.24.
Next, the refractive index difference between the silicon nitride layer and the silicon oxide layer is such that the refractive index difference is 0.61 when the blue (B) wavelength is 400 to 515 nm, and the refractive index difference is 0.57 when the green (G) wavelength is 490 to 590 nm. When the red (R) wavelength is 570 to 650 nm, the refractive index difference is 0.55.

  First, a boundary surface between a microlens and a color filter will be described for a first medium boundary example. The relationship between the refractive indexes of the media is microlens <color filter. The refractive index difference and its magnitude relationship in the blue, green, and red wavelength regions are 0.02 (blue) <0.06 (green) <0.18 (red), respectively. Here, when the boundary surface between the microlens 13 and the color filter 12 is considered as a plane as shown in FIG. 3, the blue, green, and red lights LB, LG, and LR that have passed through the microlens are respectively The focal position shifts upward in the order of red, green, and blue due to the difference in refractive index with wavelength.

  Therefore, FIG. 4 is a configuration diagram showing the first embodiment of the solid-state imaging device according to the present invention. In this example, the refractive index of the medium formed above the photosensor is such that the upper medium <the lower medium. In the present embodiment, when the refractive index satisfies the relationship of microlens <color filter, the shape of the boundary surface between the microlens 13 [13R, 13G, 13B] and the color filter 12 [12R, 12G, 12B] is set. Depending on the pixel of each color. For a green pixel having an intermediate refractive index difference among the three colors, the shape of the boundary surface is made flat. No lens effect occurs between the green pixel micro lens 13G and the green color filter component 12G. With reference to the flat boundary surface shape of the green pixel, for the blue pixel having a small refractive index difference among the three colors, the boundary surface shape is made concave, and the red color having the large refractive index difference among the three colors is changed. For the pixels, the shape of the boundary surface is made convex so that each has a lens effect. A concave lens 21 is formed between the blue lens microlens 13B and the blue color filter component 12B, and a convex lens 22 is formed between the red pixel microlens 13R and the red color filter component 12R.

According to the solid-state imaging device according to the first embodiment, it is possible to eliminate the shift of the focal position of incident light of each color by changing the shape of the boundary surface between the microlens and the color filter to have a lens effect.
That is, as in this example, at the medium boundary where the refractive index is such that the microlens is smaller than the medium boundary example of the color filter, the blue light LB that has passed through the concave lens 21 on the boundary surface has a focal position downward. The focal point of the red light LR that has shifted and passed through the convex lens 22 on the boundary surface is shifted upward. At this time, the focal position can be adjusted for each color signal by adjusting the lens curvature formed at the boundary surface according to the refractive index difference between the media. Thereby, the focal positions of the blue light LB and the red light LR are aligned with the focal position of the green light LG.

FIG. 5 is a configuration diagram showing a second embodiment of the solid-state imaging device according to the present invention. In the case where the refractive index of the medium formed above the photosensor 3 is the upper medium <the lower medium, in this example, the relationship between the refractive indices of the respective media is when the microlens <the color filter. The shape of the boundary surface between the microlens 13 and the color filter 12 is all convex for each RGB color signal. That is, convex lenses 24, 25 and 26 are formed on the boundary surfaces corresponding to red, green and blue, respectively. The curvature of the convex shape (convex lens 24, 25, 26) of each boundary surface increases in the order of blue <green <red. That is, in this example, since the curvature of the convex shape on which the red signal is incident is increased and the effect as a lens is great, the focal position is shifted upward. For other green and blue signals, the focal position is adjusted by changing the curvature of the convex shape inside the microlens. At this time, the focal position can be adjusted for each color signal by adjusting the lens curvature of each boundary surface according to the refractive index difference between the media, and the deviation of the focal position can be eliminated.
In this way, by correcting the chromatic aberration due to the wavelength dependence of the refractive index of each medium boundary for each pixel, it is possible to eliminate the deviation of the condensing position on the photosensor 3 for each color signal.

  Next, a boundary surface between a silicon nitride layer and a silicon oxide layer will be described as a second medium boundary example shown in FIG. The relationship of the refractive index between the media is silicon nitride> silicon oxide. The refractive index difference and the magnitude relationship in the blue, green, and red wavelength regions are 0.61 (blue)> 0.57 (green)> 0.55 (red), respectively. Here, when the boundary surface between the silicon nitride layer 11 and the silicon oxide layer 10 is considered as a plane as shown in FIG. 6, the blue, green, and red lights LB, LG, and LR that have passed through the silicon nitride layer 11 are The focal position shifts downward in the order of blue, green, and red due to the difference in refractive index of each wavelength.

FIG. 7 is a configuration diagram showing a third embodiment of the solid-state imaging device according to the present invention. When the refractive index of the medium formed above the photosensor 3 is upper medium> lower medium, in this example, the relationship of the refractive index between the media is silicon nitride> silicon oxide.
For the blue pixel having a large refractive index difference among the three colors, the shape of the silicon nitride layer 11 and the boundary surface of the silicon oxide layer 10 is a convex shape, and the red pixel having a small refractive index difference among the three colors. With respect to, by making the shape of the silicon nitride layer 11 and the boundary surface of the silicon oxide layer 10 concave, each has a lens effect and can eliminate the deviation of the focal position. Here, in the green pixel, the shape of the boundary surface between the silicon nitride layer 11 and the silicon oxide layer 10 is made flat as in FIG. When the refractive index is in the relationship of upper medium> lower medium, the concave shape formed on the boundary surface of the red pixel corresponds to the convex lens 27 when viewed as a lens effect, and is formed on the boundary of the blue pixel. The convex shape is equivalent to the convex lens 28 when viewed as a lens effect.

  According to the solid-state imaging device according to the third embodiment, the medium passes the convex lens 28 at the boundary surface between the silicon nitride layer 11 and the silicon oxide layer 10 at the medium boundary where the refractive index has a relationship of silicon nitride> silicon oxide. The focus position of the blue light LB is shifted downward, and the focus position of the red light LR that has passed through the concave lens 27 is shifted upward. At this time, the focal position can be adjusted by adjusting the lens curvature according to the refractive index difference between the media. As a result, the focal positions of the blue light LB and the red light LR are aligned with the green focal position. In this way, by correcting the chromatic aberration due to the wavelength dependence of the refractive index of each medium boundary for each pixel, it is possible to eliminate the shift of the light collection position on the photosensor 3 for each color signal.

FIG. 8 is a configuration diagram showing a fourth embodiment of the solid-state imaging device according to the present invention. When the refractive index of the medium formed above the photosensor 3 is upper medium> lower medium, in this example, the relationship of the refractive index between the media is silicon nitride> silicon oxide.
In the solid-state imaging device according to the fourth embodiment, the shape of the boundary surface between the silicon nitride layer 11 and the silicon oxide layer 10 corresponding to each color pixel of red, green, and blue is all concave (convex when viewed as a lens effect) Lenses 29, 30, 31), and the curvature of the concave shape (convex lenses 29, 30, 31) is made to increase in the order of blue <green <red. The larger the concave curvature of the boundary surface between the silicon nitride layer 11 and the silicon oxide layer 10, the greater the effect as a lens, and the focal position shifts upward. In this case, the concave shape of the boundary surface corresponds to a convex lens when viewed as a lens effect as described with reference to FIG. 7, and includes a convex lens 29 corresponding to a red pixel and a convex lens 30 corresponding to a green pixel. The curvature increases in the order of the convex lens 31 corresponding to the blue pixel. Therefore, it is possible to eliminate the shift of the focal position of the light beams LR, LG and LB of each color. In this way, by correcting the chromatic aberration due to the wavelength dependence of the refractive index of each medium boundary for each pixel, it is possible to eliminate the deviation of the condensing position on the photosensor 3 for each color signal.

  In the above-described embodiment, as a boundary surface shape of a medium having a refractive index difference, a combination of a concave shape, a convex shape, and a flat shape corresponding to each color pixel of red, green, and blue, all of which are only concave shapes. The example of combination and the example of combination only of convex shape were explained, but other examples of combination of concave shape and convex shape, example of combination of concave shape and flat shape, example of combination of convex shape and flat shape Can also be configured, and have the same effect.

FIG. 9 is a process diagram showing the embodiment of the method for manufacturing the solid-state imaging device according to the first embodiment shown in FIG.
It is.
First, as shown in FIG. 9A, after the photosensor 3, the vertical transfer register 7, the light shielding film 9, the silicon oxide layer 10, and the silicon nitride layer 11 of each light receiving unit are formed in the imaging region, A green filter component 12G having a flat surface is formed in a portion corresponding to the green pixel. At this time, the thickness of the green filter component 12G is set to be thicker than the blue filter component 12B to be formed later. Here, each color filter component can be formed of an organic material, for example, a material film containing a pigment in a photosensitive resin. The green filter component 12G is formed by applying a photoresist film having a green pigment, and exposing and developing a predetermined pattern using a photolithography method. After exposure, it is cured by heating while irradiating with ultraviolet rays.

  Next, as shown in FIG. 9B, a photoresist film containing a blue dye is applied to the entire surface of the silicon nitride layer 11 containing the green filter component 12G. At this time, by applying the photoresist film to be thinner than the film thickness of the green filter component 12G, the photoresist film is formed so that the surface is concave in a portion other than the green filter component 12G.

  Next, as shown in FIG. 9C, the surface is concaved by patterning using a photolithography method so that the blue dye-containing photoresist film corresponding to the pixel remains in blue. A blue filter component 12B is formed. Thereafter, the blue filter component 12B is cured in the same manner.

  Next, as shown in FIG. 9 (d), a photoresist film containing a red pigment is applied to the entire surface, and similarly, patterning is performed using a photolithography method to apply a red filter component 12R to a portion corresponding to a red pixel. Form. At this time, the pattern of the red filter component 12R is a small pattern so as not to overlap with the pattern of the adjacent filter components 12G and 12B. The surface of the red filter component 12R before curing has a concave shape.

  Next, as shown in FIG. 9 (e), the red filter component 12R is subjected to a thermal reflow process to form a surface convex red filter component 12R pattern.

Here, the convex shape is adjusted by the pattern size at the time of patterning of the red filter 12R, the temperature and time of thermal reflow. Thus, a desired structure can be obtained.

  Thereafter, microlenses 13 are formed on the color filter components 12R, 12G, and 12B. As a result, a target solid-state imaging device in which the boundary surface between the microlens 13 and the color filter components 12R, 12G, and 12B has a convex shape, a flat shape, and a concave shape is obtained.

  According to the method for manufacturing a solid-state imaging device according to the present embodiment, the shape of the upper surface of the color filter is changed for each pixel, and the microlens is formed on the color filter. The shape can be changed as shown in FIG. 4, and the chromatic aberration due to the wavelength dependence of the refractive index of each medium boundary between the microlens and the color filter is corrected for each pixel, and the condensing position on the photosensor 3 for each color signal It is possible to manufacture a solid-state imaging device that can eliminate the deviation.

FIG. 10 is a process diagram showing another embodiment of the method of manufacturing the solid-state imaging device according to the third embodiment shown in FIG.
First, as shown in FIG. 10A, after forming the photosensor 3, the vertical transfer register, the light shielding film 9, and the silicon oxide layer 10 of each pixel, a blue pixel that forms a convex shape on the silicon oxide layer 10 is formed. A photoresist pattern is selectively formed on the portion corresponding to the above by a photolithography technique, and a convex surface resist pattern is formed by thermal reflow.

  Subsequently, as shown in FIG. 10B, anisotropic etching is performed under the condition that the selection ratio of resist to silicon oxide is 1, and the resist pattern 40 is transferred to the silicon oxide layer 10. Thereby, the silicon oxide layer 10 whose surface has a convex shape 10B is formed. At this time, since the silicon oxide layer 10 becomes thin, the film thickness to be etched here is added in advance to a necessary film thickness. The convex shape is adjusted by the resist film thickness for forming the lens shape, the thermal reflow temperature, and the like.

  Next, as shown in FIG. 10C, a photoresist pattern 42 is formed so that the window 41 opens in a portion corresponding to the red pixel forming the concave shape.

  Thereafter, as shown in FIG. 10D, the silicon oxide layer 10 is etched by isotropic etching using the resist pattern 42 as a mask, and the concave shape 10R is formed on the silicon oxide layer 10 corresponding to the red pixel. Form. The concave shape 10R is adjusted by changing the conditions such as adding anisotropy to the isotropic etching.

  Next, as shown in FIG. 10E, the mask resist 42 is peeled off. As a result, the silicon oxide layer 10 having a surface convex shape 10B corresponding to the blue pixel, a surface flat shape corresponding to the green pixel, and a surface concave shape corresponding to the red pixel is formed.

  Next, as shown in FIG. 10F, a silicon nitride layer 11 having a different refractive index is formed on the silicon oxide layer 10. Thereby, a lens for each color signal can be formed between the silicon oxide layer 10 and the silicon nitride layer 11. For a blue pixel having a large refractive index difference, the shape of the silicon nitride layer 11 and the boundary surface of the silicon oxide layer 10 is a convex shape, and for a red pixel having a small refractive index difference among the three colors, a silicon nitride layer is used. The shape of the boundary between the silicon oxide layer 10 and the silicon oxide layer 10 is made concave to give a lens effect to each of the green pixels. A target solid-state imaging device that eliminates the deviation is obtained.

  According to the manufacturing method of the solid-state imaging device according to the present embodiment, the lens for each color signal is formed on the boundary surface between the silicon oxide layer 10 and the silicon nitride layer 11, and thus the refractive index of each medium boundary is formed in this way. Thus, it is possible to manufacture a solid-state imaging device capable of correcting the chromatic aberration due to the wavelength dependence for each pixel and eliminating the shift of the condensing position on the photosensor 3 for each color signal.

  The solid-state imaging device and the manufacturing method thereof according to the present embodiment have been described using the RGB three-color filter. However, the present invention can also be applied to a case where four or more color filters and complementary color filters are provided.

  The solid-state imaging device according to this embodiment can be applied to any of a frame transfer method, an interline transfer method, and a frame interline transfer method.

  Although the solid-state imaging device and the manufacturing method thereof according to the present embodiment have been described using the CCD solid-state imaging device, it can also be applied to a CMOS solid-state imaging device.

1 is a cross-sectional configuration diagram showing an embodiment of a solid-state imaging device according to the present invention. It is a figure which shows the refractive index difference of each medium of FIG. It is a block diagram which shows the principal part of the conventional solid-state imaging device. 1 is a configuration diagram illustrating a first embodiment of a solid-state imaging device according to the present invention. It is a block diagram which shows 2nd Embodiment of the solid-state imaging device which concerns on this invention. It is a block diagram which shows the principal part of the conventional solid-state imaging device. It is a block diagram which shows 3rd Embodiment based on this invention. It is a block diagram which shows 4th Embodiment based on this invention. a to e are process diagrams illustrating a method of manufacturing the solid-state imaging device according to the present embodiment in FIG. 4. FIGS. 8A to 8F are process diagrams illustrating a method for manufacturing the solid-state imaging device according to the present embodiment in FIGS. It is sectional drawing which shows the conventional solid-state imaging device. It is a figure which shows the refractive index of each medium of FIG. a It is sectional drawing which shows the principal part of the center of the conventional imaging region. b is a cross-sectional view showing a main part around a conventional imaging region.

Explanation of symbols

  1 .... Solid-state imaging device 2 .... Silicon substrate 3 .... Photo sensor 4 .... Channel region 5 .... Gate insulation film 6 .... Transfer electrode 7 .... Vertical transfer register 8 .... Interlayer insulation Film 9 .. light shielding film 10.. Silicon oxide layer 11 silicon nitride layer 12 [12R, 12G, 12B] color filter 13 micro lens 21 concave lens 22 24, 25, 26, 27, 28, 29, 30, 31,... Convex lens, 40, 42 .. resist pattern, 41... Window, 101... Solid state imaging device, 102. ..Photosensor, 104 ..Channel region, 105 ..Gate insulating film, 106 ..Transfer electrode, 107 ..Vertical transfer register, 108 ..Interlayer insulating film, 109 ..Light-shielding film, 110. 111 ... silicon nitride layer, 112 ... color filter, 113 ... microlenses

Claims (7)

A solid-state imaging device including a color filter above each photosensor serving as a light receiving unit,
A solid-state imaging device, wherein a boundary surface shape of a medium having a refractive index difference above a photosensor is different for each pixel in accordance with each color signal. A solid-state imaging device including a color filter above each photosensor serving as a light receiving unit,
When the refractive index of the medium formed above the photosensor is an upper medium <lower medium,
The medium boundary shape of the pixel having a large refractive index difference in the wavelength range corresponding to the color of each pixel is formed in a convex shape,
A solid-state imaging device, wherein a medium boundary shape of a pixel having a small refractive index difference is formed in a concave shape. A solid-state imaging device including a color filter above each photosensor serving as a light receiving unit,
When the refractive index of the medium formed above the photosensor is an upper medium <lower medium,
A solid-state imaging device, wherein the medium boundary shape is a convex shape, and the curvature of the convex shape increases as the refractive index difference in the wavelength range corresponding to the color of each pixel increases. A solid-state imaging device including a color filter above each photosensor serving as a light receiving unit,
When the refractive index of the medium formed above the photosensor is higher medium> lower medium,
The medium boundary shape of the pixel having a large refractive index difference in the wavelength range corresponding to the color of each pixel is formed in a concave shape,
A solid-state imaging device, wherein a medium boundary shape of a pixel having a small refractive index difference is formed in a convex shape. A solid-state imaging device including a color filter above each photosensor serving as a light receiving unit,
When the refractive index of the medium formed above the photosensor is higher medium> lower medium,
A solid-state imaging device characterized in that the medium boundary shape is a concave shape, and the curvature of the concave shape increases as the refractive index difference in the wavelength range corresponding to the color of each pixel increases. A method for manufacturing a solid-state imaging device including a color filter composed of a plurality of color filter components, which is a lower medium layer above a photosensor of each light receiving unit,
Forming a first color filter component having a flat upper surface among the color filters;
Forming a second color filter material film on the entire surface including the first color filter component so that the upper surface of the portion other than the first color filter component has a concave shape;
Patterning the second color filter material film by a photolithography method to form a second color filter component having a concave upper surface;
Forming a third color filter material film and patterning by a photolithography method to form a third color filter;
Forming a convex shape by heat reflowing the upper surface of the third color filter component;
A method of manufacturing a solid-state imaging device, comprising: forming a microlens as an upper medium layer on each color filter. A method of manufacturing a solid-state imaging device including a color filter including a plurality of filter components above a photosensor of each light receiving unit,
Forming a convex portion in a portion to be the first pixel on the lower medium layer;
Forming a resist layer having an opening in a portion to be the second pixel of the lower medium layer;
Performing isotropic etching through the opening to form a concave portion in the lower medium layer;
Laminating an upper medium layer having a refractive index larger than that of the lower medium layer after removing the resist layer;
A method of manufacturing a solid-state imaging device, comprising: forming each color filter component and a microlens on the upper medium layer.

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