JP2011249462A - Solid state image pickup device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid state image pickup device and its manufacturing method capable of reducing optical color mixture.SOLUTION: According to an embodiment, the solid state image pickup device is a backside illuminated type solid state image pickup device comprising a semiconductor substrate having a surface which has disposed thereon a plurality of photoelectric conversion sections including a first photoelectric conversion section and a second photoelectric conversion section adjacent to the first photoelectric conversion section and a reverse side opposite to the surface; a first color filter layer disposed on the reverse side of the first photoelectric conversion section so that a first color light will impinge upon the first photoelectric conversion section; and a second color filter layer disposed adjacent to the first color filter layer on the reverse side of the second photoelectric conversion section so that a second color light will impinge upon the second photoelectric conversion section. The first color filter layer includes a body section having a first thickness and an edge section disposed around the body section and having a second thickness thinner than the first thickness. The second color filter layer covers the edge section in a boundary region with the first color filter layer.

Description

  Embodiments described herein relate generally to a solid-state imaging device and a method for manufacturing the same.

  Conventionally, in a solid-state imaging device in which a plurality of color filters are arranged corresponding to the arrangement of a plurality of pixels (photodiodes), light that has passed through the color filters is incident on adjacent pixels instead of the corresponding pixels. Optical color mixing resulting from this is a problem. In such a prior art, it is desired to reduce optical color mixing.

JP 2001-28432 A

  An object of the embodiment of the present invention is to provide, for example, a solid-state imaging device capable of reducing optical color mixing and a manufacturing method thereof.

  According to the embodiment, the back-illuminated solid-state imaging device includes a plurality of photoelectric conversion units including a first photoelectric conversion unit and a second photoelectric conversion unit adjacent to the first photoelectric conversion unit. A semiconductor substrate having a disposed surface and a back surface opposite to the front surface, and the back surface side of the first photoelectric conversion unit so that light of the first color is incident on the first photoelectric conversion unit. The first color filter layer and the first color filter layer on the back surface side of the second photoelectric conversion unit so that the second color light is incident on the second photoelectric conversion unit. A second color filter layer disposed adjacent to the first color filter layer, wherein the first color filter layer is disposed around the main body portion and the first thickness. An edge having a thin second thickness, wherein the second color filter layer is in a boundary region with the first color filter layer. The solid-state imaging device is provided, characterized in that covers the edges that.

  Further, according to another embodiment, there is provided a method for manufacturing a backside illumination type solid-state imaging device, which is adjacent to the first photoelectric conversion unit and the first photoelectric conversion unit on the front surface side in the semiconductor substrate. A step of forming a plurality of photoelectric conversion units including a second photoelectric conversion unit, and a spectral transmission in a wavelength region of the first color in a region corresponding to the first photoelectric conversion unit on the back side of the semiconductor substrate Forming a first layer to be a first color filter layer having a rate peak, a main body having a first thickness, and being disposed around the main body and being thinner than the first thickness A step of selectively thinning the edge of the first layer so as to form the first color filter layer including an edge having a second thickness; and a back surface side of the semiconductor substrate. The spectral transmittance of the region corresponding to the second photoelectric conversion unit in the second color wavelength region is Forming a second color filter layer having a mark so as to cover the edge in a boundary region with the first color filter layer. Provided.

The figure which shows the structure of the solid-state imaging device concerning embodiment. The figure which shows the structure of the solid-state imaging device concerning embodiment. The figure which shows the manufacturing method of the solid-state imaging device concerning embodiment. The figure which shows the manufacturing method of the solid-state imaging device concerning the modification of embodiment. The figure which shows the manufacturing method of the solid-state imaging device concerning the other modification of embodiment. The figure which shows the structure of the solid-state imaging device concerning a comparative example. The figure which shows the structure of the solid-state imaging device concerning another comparative example.

Hereinafter, a solid-state imaging device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.
(Embodiment)

  The configuration of the solid-state imaging device 1 according to the embodiment will be described with reference to FIGS. 1-1 and 1-2. FIG. 1-1A shows a configuration of a cross section passing through a blue color filter layer and a green color filter layer. FIG. 1-1B shows a cross-sectional configuration passing through the red color filter layer and the green color filter layer. FIG. 1-2C illustrates a layout configuration of a plurality of color filter layers. 1-1 (a) corresponds to a cross section taken along line AA in FIG. 1-2 (c), and FIG. 1-1 (b) is a cross-sectional view along B- in FIG. 1-2 (c). Corresponds to the cross section cut along line B. FIG. 1-2D is a diagram schematically illustrating the dimming pattern.

  The solid-state imaging device 1 includes a semiconductor substrate 10, a planarization layer 20, a color filter array CFA, a planarization layer 30, and a microlens array MLA. The semiconductor substrate 10 has a front surface 10a and a back surface 10b. The solid-state imaging device 1 is a backside illumination type solid-state imaging device in which light enters from the back surface 10 b side of the semiconductor substrate 10.

  In the well region 12 of the semiconductor substrate 10, a plurality of photoelectric conversion units (a plurality of pixels) are arranged on the surface 10 a side. The plurality of photoelectric conversion units are arranged two-dimensionally, for example. The well region 12 contains a first conductivity type (for example, P-type) impurity at a low concentration. Each photoelectric conversion unit is, for example, a photodiode and includes a charge accumulation region. The charge storage region includes a second conductivity type (for example, N type) impurity opposite to the first conductivity type in a concentration higher than the concentration of the first conductivity type impurity in the well region 12.

  The plurality of photoelectric conversion units include a photoelectric conversion unit (first photoelectric conversion unit) 11g, a photoelectric conversion unit (second photoelectric conversion unit) 11b, and a photoelectric conversion unit (third photoelectric conversion unit) 11r. The photoelectric conversion unit 11b is adjacent to the photoelectric conversion unit 11g in the direction along the line AA illustrated in FIG. The photoelectric conversion unit 11r is adjacent to the photoelectric conversion unit 11g in a direction crossing the adjacent direction of the photoelectric conversion unit 11b (a direction along the line BB illustrated in FIG. 1-2C).

  The planarization layer 20 covers the back surface 10 b of the semiconductor substrate 10. Thereby, the planarization layer 20 provides a flat surface on which the color filter array CFA is disposed.

  The color filter array CFA is disposed on the surface of the planarization layer 20. In the color filter array CFA, a plurality of color filter layers are arranged two-dimensionally, for example, corresponding to the array of the plurality of photoelectric conversion units.

  The planarization layer 30 covers a plurality of color filter layers. Thereby, the planarization layer 30 provides a flat surface on which the microlens array MLA is disposed.

  The microlens array MLA is disposed on the surface of the planarization layer 30. In the microlens array MLA, a plurality of microlenses are arranged two-dimensionally, for example, corresponding to the array of the plurality of photoelectric conversion units. For example, the micro lenses MLg, MLb, and MLr are arranged so as to be condensed on the photoelectric conversion units 11g, 11b, and 11r, respectively.

  Next, a specific configuration of the plurality of color filter layers in the color filter array CFA will be described.

  In the color filter array CFA, for example, as shown in FIG. 1-2C, the green color filter layers 40g1 and 40g2 arranged in the diagonal direction and the red arranged in the other diagonal direction according to the Bayer arrangement. The unit arrangement of the four color filter layers formed by the color filter layer 40r1 and the blue color filter layer 40b1 is two-dimensionally and repeatedly arranged. Therefore, in the following, a green color filter layer (first color filter layer) 40g1, a blue color filter layer (second color filter layer) 40b1, and a red color filter layer (third color filter layer) 40r1 will be described. A related configuration will be described as an example, but the same applies to configurations related to other corresponding color filter layers.

  The color filter layer (first color filter layer) 40g1 is arranged on the back surface 10b side of the photoelectric conversion unit 11g so that green (first color) light enters the photoelectric conversion unit 11g. That is, the color filter layer 40g1 is disposed so as to include the photoelectric conversion unit 11g when seen through from the direction perpendicular to the back surface 10b. The color filter layer 40g1 has a spectral transmittance peak in the green wavelength region.

  The color filter layer 40g1 includes a main body portion 40g11 and an edge portion 40g12. The main body 40g11 is disposed inside the edge 40g12. The edge portion 40g12 is disposed around the main body portion 40g11. The main body 40g11 is, for example, a substantially quadrangle (a quadrangle or a shape with rounded corners), and the edge 40g12 is, for example, a substantially square frame.

  The main body 40g11 has a thickness (first thickness) Dg11. The edge portion 40g12 has a thickness (second thickness) Dg12 smaller than the thickness Dg11. Accordingly, the main body portion 40g11 and the edge portion 40g12 cover the planarizing layer 20, and the height of the main body portion 40g11 from the back surface 10b of the semiconductor substrate 10 is from the back surface 10b of the semiconductor substrate 10 of the edge portion 40g12. (See FIGS. 1-1 (a) and 1-1 (b)).

  The color filter layer (third color filter layer) 40r1 is arranged on the back surface 10b side of the photoelectric conversion unit 11r so that red (third color) light enters the photoelectric conversion unit 11r. That is, the color filter layer 40r1 is disposed so as to include the photoelectric conversion unit 11r when seen through from the direction perpendicular to the back surface 10b. The color filter layer 40r1 has a spectral transmittance peak in the red wavelength region.

  The color filter layer 40r1 includes a main body (third main body) 40r11 and an edge (third edge) 40r12. The main body portion 40r11 is disposed inside the edge portion 40r12. The edge portion 40r12 is disposed around the main body portion 40r11. The main body 40r11 is, for example, a substantially quadrangle (a quadrangle or a shape with rounded corners), and the edge 40r12 is, for example, a substantially square frame.

  The main body 40r11 has a thickness (fifth thickness) Dr11. The edge portion 40r12 has a thickness (sixth thickness) Dr12 that is smaller than the thickness Dr11. Accordingly, the main body portion 40r11 and the edge portion 40r12 cover the planarization layer 20, and the height of the main body portion 40r11 from the back surface 10b of the semiconductor substrate 10 is from the back surface 10b of the semiconductor substrate 10 of the edge portion 40r12. (See FIG. 1-1 (b)).

  The color filter layer (second color filter layer) 40b1 is disposed on the back surface 10b side of the photoelectric conversion unit 11b so that blue (second color) light is incident on the photoelectric conversion unit 11b. That is, the color filter layer 40b1 is disposed so as to include the photoelectric conversion unit 11b when seen through from the direction perpendicular to the back surface 10b. The color filter layer 40b1 has a spectral transmittance peak in the blue wavelength region.

  The color filter layer 40b1 includes a main body (second main body) 40b11, an edge (second edge) 40b12, and an extension 40b13. The main body 40b11 is disposed inside the edge 40b12. The edge portion 40b12 is disposed around the main body portion 40b11. The main body 40b11 is, for example, a substantially quadrangle (a quadrangle or a shape with rounded corners), and the edge 40b12 is, for example, a substantially square frame. The extending portion 40b13 extends from the corner adjacent to the color filter layer 40g1 and the color filter layer 40r1 in the edge portion 40b12 to the direction along the back surface 10b of the photoelectric conversion unit 11b between the color filter layer 40g1 and the color filter layer 40r1. It extends.

  The main body portion 40b11 has a thickness (third thickness) Db11. The edge portion 40b12 and the extending portion 40b13 have a thickness (fourth thickness) Db12 that is thinner than the thickness Db11. Accordingly, the main body portion 40b11, the edge portion 40b12, and the extending portion 40b13 are covered with the planarizing layer 30, and the semiconductor substrate 10 on the surface on the semiconductor substrate 10 side in each of the edge portion 40b12 and the extending portion 40b13. The height from the back surface 10b of the main body portion 40b11 is higher than the height from the back surface 10b of the semiconductor substrate 10 on the surface of the main body 40b11 (FIGS. 1-1A and 1-1B). reference).

  The edge part 40b12 in the color filter layer 40b1 does not cover the main body part 40g11 in the color filter layer 40g1, but covers the edge part 40g12 in the boundary region with the color filter layer 40g1 (see FIG. 1-1 (a)). The edge 40b12 has a spectral transmittance peak in the blue wavelength range, whereas the edge 40g12 has a spectral transmittance peak in the green wavelength range, so that light passing through the edge 40b12 passes through the edge 40g12. Difficult to pass. Thereby, the edge 40b12 and the edge 40g12 covered with the edge 40b12 function as a light reducing layer (hereinafter referred to as a first light reducing layer).

  The extending part 40b13 in the color filter layer 40b1 covers both the edge part 40g12 and the edge part 40r12 in the boundary region between the color filter layer 40g1 and the color filter layer 40r1. The extended portion 40b13 has a spectral transmittance peak in the blue wavelength region, whereas the edge portion 40g12 and the edge portion 40r12 have spectral transmittance peaks in the green and red wavelength regions, respectively. The light that has passed through is difficult to pass through each of the edge 40g12 and the edge 40r12. Accordingly, the extended portion 40b13 and the edge portion 40g12 and the edge portion 40r12 covered by the extended portion 40b13 function as a light reducing layer (hereinafter referred to as a second light reducing layer).

  The layout of the first dimming layer and the second dimming layer is schematically shown in FIG. The first dimming layer pattern (pattern indicated by a solid line) extending in a rectangular frame shape and the second dimming layer pattern (pattern indicated by a broken line) extending in a rectangular frame shape are vertically and horizontally in the drawing. They are two-dimensionally arranged at a pitch of 2 pixels with a shift of 1 pixel pitch. That is, the dimming pattern formed by the first dimming layer and the second dimming layer includes a plurality of dimming patterns so as to define the opening area of each color filter layer as shown in FIG. Between the main body portions of the color filter layers, the color filter layers extend in a lattice pattern. Thereby, the main body portion of each color filter layer becomes an opening region.

  Further, the pattern width W1 of the first dimming layer is smaller than the pattern width W2 of the second dimming layer. For example, the width of the overlap between the edge portion 40b12 and the edge portion 40g12 (see FIG. 1-1A) when seen through from the direction perpendicular to the back surface 10b of the semiconductor substrate 10 is set between the extension portion 40b13 and the edge portion 40g12. When the width is the same as the overlap width (see FIG. 1-1B), the pattern width W1 of the first dimming layer is about ½ of the pattern width W2 of the second dimming layer. Accordingly, the width OWb of the opening region of the color filter layer 40b1 can be made larger than the width OWg of the opening region of the color filter layer 40g1, and can be made larger than the width OWr of the opening region of the color filter layer 40r1. That is, the opening area of the color filter layer 40b1 can be larger than the opening area of the color filter layer 40g1, and can be larger than the opening area of the color filter layer 40r1.

  Next, a method for manufacturing the solid-state imaging device 1 according to the embodiment will be described with reference to FIG. 2A to 2G are process cross-sectional views illustrating a method for manufacturing the solid-state imaging device 1, and FIGS. 2H to 2N are plan views corresponding to FIGS. 2A to 2G, respectively. It is. The cross sections shown in FIGS. 2A to 2G correspond to the cross section taken along line AA in FIG. 1-2C, and the planes shown in FIGS. This corresponds to the plane shown in FIG. In the following, it is related to the green color filter layer (first color filter layer) 40g1, the blue color filter layer (second color filter layer) 40b1, and the red color filter layer (third color filter layer) 40r1. The method for manufacturing the portion will be described as an example, but the same applies to the method for manufacturing the portion related to other corresponding color filter layers.

  In the steps shown in FIGS. 2A and 2H, a semiconductor substrate having a well region containing a first conductivity type (for example, P-type) impurity at a low concentration is prepared. The semiconductor substrate is made of, for example, silicon. The P-type impurity is, for example, boron. Then, a plurality of photoelectric conversion units including the photoelectric conversion units 11g and 11b are formed on the surface side in the well region of the semiconductor substrate. Thereby, the semiconductor substrate 10 in which a plurality of photoelectric conversion units (a plurality of pixels) are arranged on the surface 10a side in the well region 12 is obtained. Each photoelectric conversion unit is a photodiode, for example, and is formed so as to include a charge accumulation region. The charge storage region is formed to contain a second conductivity type (for example, N type) impurity opposite to the first conductivity type at a concentration higher than the concentration of the first conductivity type impurity in the well region 12. . The N-type impurity is, for example, phosphorus or arsenic. Then, the planarizing layer 20 is formed on the back surface 10 b of the semiconductor substrate 10. The planarization layer 20 is formed with a predetermined resin, for example.

  In the step shown in FIGS. 2B and 2I, a layer (first layer) to be the color filter layer 40g1 in the region corresponding to the photoelectric conversion portion 11g on the back surface 10b side of the semiconductor substrate 10, that is, the surface of the planarization layer 20. Layer) 40g1i. Specifically, for example, a first resin layer to be the color filter layer 40g1 is applied to the surface of the planarizing layer 20 by spin coating. The first resin layer is formed of, for example, a resist material containing a green pigment or dye so as to have a spectral transmittance peak in the green wavelength region. Thereafter, the first resin layer is etched by photolithography into a pattern in which a plurality of square green layers are arranged in a checkered pattern (see FIG. 2I). Thereby, for example, the green layer 40g1i is formed.

  In the steps shown in FIGS. 2C and 2J, the layer 40r1i to be the color filter layer 40r1 is formed in the region corresponding to the photoelectric conversion portion 11r on the back surface 10b side of the semiconductor substrate 10, that is, the surface of the planarization layer 20. To do. Specifically, for example, a second resin layer to be the color filter layer 40r1 is applied to the exposed surface of the planarizing layer 20 by spin coating. The second resin layer is formed of, for example, a resist material containing a red pigment or dye so as to have a spectral transmittance peak in the red wavelength region. Thereafter, a pattern in which a plurality of square red layers are arranged in every other row of the plurality of exposed regions of the planarizing layer 20 by a photolithography method (FIG. 2 ( j) See)). Thereby, for example, the red layer 40r1i is formed.

  2D and 2K, the edge of each green layer including the green layer 40g1i and the edge of each red layer including the red layer 40r1i are selectively selected by, for example, photolithography. An exposed sacrificial film pattern 70 is formed. That is, the sacrificial film pattern 70 covers a portion to be a main body portion in each green layer, covers a portion to be a main body portion in each red layer, and covers an exposed surface of the planarizing layer 20. The sacrificial film pattern 70 is formed of, for example, a resist. The thickness of the sacrificial film pattern 70 depends on the difference between the thickness Dg11 of the main body 40g11 and the thickness Dg12 of the edge 40g12 in the color filter layer 40g1 (Dg11−Dg12, see FIG. 1-1A), the color filter The layer 40r1 is adjusted so as to correspond to the difference between the thickness Dr11 of the main body 40r11 and the thickness Dr12 of the edge 40r12 (Dr11-Dr12, see FIG. 1-1B).

  In the steps shown in FIGS. 2E and 2L, etch back processing is performed to etch the entire surface until the sacrificial film pattern 70 is completely removed. Thereby, the removal of the sacrificial film pattern 70 and the selective etching of the edge of each green layer and the edge of each red layer are performed in parallel. When the sacrificial film pattern 70 is completely removed, the edge portion of the green layer 40g1i is etched at a thickness corresponding to the difference (Dg11-Dg12). Similarly, when the sacrificial film pattern 70 is completely removed, the edge portion of the red layer 40r1i is etched at a thickness corresponding to the difference (Dr11-Dr12).

  As described above, in the steps shown in FIGS. 2D and 2K and the steps shown in FIGS. 2E and 2L, for example, the edge of each green layer including the green layer 40g1i and the red layer 40r1i. The edge of each red layer including the film is selectively thinned. Thereby, for example, a color filter layer 40g1 including a main body portion 40g11 having a thickness Dg11 and an edge portion 40g12 having a thickness Dg12 thinner than the thickness Dg11 is formed. At the same time, for example, a color filter layer 40r1 including a main body portion 40r11 having a thickness Dr11 and an edge portion 40r12 having a thickness Dr12 thinner than the thickness Dr11 is formed. Further, a groove extending in a lattice shape is formed between the main body portion of each green color filter layer and the main body portion of each red color filter layer (see FIG. 2L). The depth of the groove is a depth corresponding to the difference (Dg11−Dg12) or the difference (Dr11−Dr12).

  In the steps shown in FIGS. 2F and 2M, for example, a blue color filter layer 40b1 is formed in the region corresponding to the photoelectric conversion portion 11b on the back surface 10b side of the semiconductor substrate 10, that is, on the surface of the planarization layer 20 and the groove. Form. Specifically, for example, a third resin layer to be the color filter layer 40b1 is applied to the exposed surface of the planarization layer 20 and the groove by spin coating. At this time, the application amount of the material of the third resin layer is set so that the height from the back surface 10b of the semiconductor substrate 10 is uniform between the surface of the third resin layer, the color filter layer 40g1, and the color filter layer 40r1. Can be adjusted. The third resin layer is formed of a resist material containing, for example, a blue pigment or dye so as to have a spectral transmittance peak in the blue wavelength region. Thereafter, the third resin layer is etched by a photolithography method into a pattern (see FIG. 2 (m)) arranged in the exposed regions of the planarizing layer 20 and the groove. If the third resin layer can be selectively applied to the exposed surface of the planarization layer 20 and the groove by adjusting the application amount of the material of the third resin layer, this etching process is not performed. May be.

  Thereby, for example, the color filter layer 40b1 is formed so that the edge 40b12 in the color filter layer 40b1 does not cover the main body 40g11 in the color filter layer 40g1, but covers the edge 40g12 in the boundary region with the color filter layer 40g1. Can be done. At the same time, for example, the color filter layer 40b1 is formed so that the extending part 40b13 in the color filter layer 40b1 covers both the edge part 40g12 and the edge part 40r12 in the boundary region between the color filter layer 40g1 and the color filter layer 40r1. obtain.

  That is, for example, a light reducing layer (hereinafter referred to as a first light reducing layer) including the edge 40b12 and the edge 40g12 covered with the edge 40b12 can be formed. In addition, for example, a light-reducing layer (hereinafter referred to as a second light-reducing layer) including the extending part 40b13 and the edge part 40g12 and the edge part 40r12 covered by the extending part 40b13 can be formed. At this time, the dimming pattern formed by the first dimming layer and the second dimming layer, as shown in FIG. 1-2 (c), defines the opening area of each color filter layer, The plurality of color filter layers extend between the main body portions in a lattice pattern. Thereby, the main body portion of each color filter layer becomes an opening region.

  In the steps shown in FIGS. 2G and 2N, the planarizing layer 30 that covers the plurality of color filter layers including the color filter layers 40g1, 40b1, and 40r1 is formed. The planarization layer 30 is made of a predetermined resin, for example. Then, a plurality of microlenses including the microlenses MLg, MLb, and MLr are formed on the surface of the planarization layer 30. For example, the microlenses MLg, MLb, and MLr are formed in regions corresponding to the photoelectric conversion units 11g, 11b, and 11r on the surface of the planarization layer 30, respectively.

  As described above, the solid-state imaging device 1 according to the embodiment is manufactured.

  Here, suppose that, as shown in FIG. 5B, in the back-illuminated solid-state imaging device, adjacent color filter layers are not overlapped in the boundary region. In this case, as shown in FIG. 5A, for example, the green color filter layer 140g1 corresponds to the photoelectric conversion unit 11g, and the blue color filter layer 140b1 corresponds to the photoelectric conversion unit 11b. At this time, for example, the light IL101 incident on the color filter layer 140b1 in the vicinity of the boundary region between the blue color filter layer 40b1 and the green color filter layer 40g1 is refracted or scattered in the boundary region (boundary surface) and the corresponding It tends to enter not the photoelectric conversion unit 11b but the adjacent photoelectric conversion unit 11g. Alternatively, for example, the light IL102 incident on the color filter layer 140g1 in the vicinity of the boundary region between the blue color filter layer 40b1 and the green color filter layer 40g1 is refracted or scattered in the boundary region (boundary surface) and correspondingly. It tends to be incident not on the photoelectric conversion unit 11g but on the adjacent photoelectric conversion unit 11b. As described above, the backside illumination type solid-state imaging device does not have a wiring layer that defines an opening region on the incident optical path, that is, between the color filter layer and the photoelectric conversion unit, as compared with the frontside illumination type solid-state imaging device. Color mixing tends to occur.

  On the other hand, in the embodiment, in the backside illumination type solid-state imaging device 1, for example, the edge 40b12 in the color filter layer 40b1 does not cover the main body 40g11 in the color filter layer 40g1, and the boundary with the color filter layer 40g1. The edge 40g12 in the region is covered (see FIG. 1-1 (a)). The edge 40b12 has a spectral transmittance peak in the blue wavelength range, whereas the edge 40g12 has a spectral transmittance peak in the green wavelength range, so that light passing through the edge 40b12 passes through the edge 40g12. Difficult to pass. Thereby, the edge part 40b12 and the edge part 40g12 covered with the edge part 40b12 function as a light reducing layer (first light reducing layer). As a result, as shown in FIG. 1-1A, the light IL1 incident on the color filter layer 40b1 in the vicinity of the boundary region between the blue color filter layer 40b1 and the green color filter layer 40g1 is a dimming layer. It is dimmed and hardly enters the adjacent photoelectric conversion unit 11g. In addition, the light IL2 incident on the color filter layer 40g1 in the vicinity of the boundary region between the blue color filter layer 40b1 and the green color filter layer 40g1 is dimmed by the light reduction layer and hardly enters the adjacent photoelectric conversion unit 11b. . Thus, according to the embodiment, optical color mixing can be reduced in the backside illumination type solid-state imaging device 1. For example, since the layer on the semiconductor substrate 10 side in the light reduction layer becomes the edge in the green or red color filter layer, the optical color mixing of medium to long wavelength light in the visible region can be effectively reduced.

  Alternatively, as shown in FIG. 6A, consider a case where adjacent color filter layers each having a uniform thickness are overlapped in a boundary region in a back-illuminated solid-state imaging device. In this case, as indicated by the oblique lines in FIG. 6B, a light reducing layer can be formed in the boundary region between adjacent color filter layers. However, for example, when the color filter layer 240b1 covers the color filter layer 240g1 in the boundary region between the blue color filter layer 240b1 and the green color filter layer 240g1, the step ST in the boundary region has a thickness D240b1 of the color filter layer 240b1. A large value corresponding to. Accordingly, in order for the planarization layer 230 to relax the step ST and provide a flat surface on which the microlens is to be disposed, the thickness D230 of the planarization layer 230 needs to be significantly larger than the step ST. . As a result, for example, since the distance between the microlenses MLg and MLb and the photoelectric conversion units 11g and 11b is increased, the light collection efficiency to the photoelectric conversion units 11g and 11b is reduced.

  On the other hand, in the embodiment, in the back-illuminated solid-state imaging device 1, the edge portions where the thicknesses of the adjacent color filter layers are reduced are overlapped in the boundary region. For example, as illustrated in FIG. 1-1, the color filter layer 40g1 includes a main body portion 40g11 having a thickness Dg11 and an edge portion 40g12 having a thickness Dg12 smaller than the thickness Dg11. The color filter layer 40b1 includes a main body portion 40b11 having a thickness Db11 and an edge portion 40b12 having a thickness Db12 that is thinner than the thickness Db11. The edge 40g12 in the color filter layer 40g1 and the edge 40b12 in the color filter layer 40b1 overlap in the boundary region between the color filter layer 40g1 and the color filter layer 40b1. Thereby, the level | step difference in a boundary area | region is reduced significantly. In particular, when the adjustment is made so that Dg12 + Db12≈Dg11≈Dg12, the step in the boundary region can be made substantially zero. Thus, since the level difference in the boundary region between adjacent color filter layers can be greatly reduced, the thickness D30 for the planarization layer 30 to provide a flat surface on which the microlenses are to be disposed can also be significantly reduced. As a result, for example, the distance between the microlenses MLg and MLb and the photoelectric conversion units 11g and 11b can be reduced, so that the light collection efficiency to the photoelectric conversion units 11g and 11b can be improved.

  In the comparative example shown in FIG. 6B, the opening area of each color filter layer has a uniform size.

  On the other hand, in the embodiment, as shown in FIG. 1-2C, the pattern width W1 of the first light reducing layer is smaller than the pattern width W2 of the second light reducing layer. For example, the width of the overlap between the edge portion 40b12 and the edge portion 40g12 (see FIG. 1-1A) when seen through from the direction perpendicular to the back surface 10b of the semiconductor substrate 10 is set between the extension portion 40b13 and the edge portion 40g12. When the width is the same as the overlap width (see FIG. 1-1B), the pattern width W1 of the first dimming layer is about ½ of the pattern width W2 of the second dimming layer. Accordingly, the width OWb of the opening region of the color filter layer 40b1 can be made larger than the width OWg of the opening region of the color filter layer 40g1, and can be made larger than the width OWr of the opening region of the color filter layer 40r1. That is, the opening area of the blue color filter layer 40b1 can be larger than the opening area of the green color filter layer 40g1, and can be larger than the opening area of the red color filter layer 40r1. As a result, for example, the sensitivity and the sensitivity ratio of each part can be arbitrarily adjusted by suppressing the opening area, for example, by suppressing the blue light receiving sensitivity from becoming weaker than that of red and green. As a result, the red and green light receiving sensitivities and the blue light receiving sensitivity can be equalized.

  In addition, for example, the edge 40b12 in the blue color filter layer 40b1 covers the edge 40g12 in the green color filter layer 40g1, thereby forming the first dimming layer. At the same time, the extended portion 40b13 in the color filter layer 40b1 covers the edge portion 40g12 and the edge portion 40r12 in the region adjacent to the edge portion 40b12, that is, in the boundary region between the color filter layer 40g1 and the color filter layer 40r1. Is formed. That is, the first dimming layer and the second dimming layer have a structure suitable for forming in a lump (by a simple process).

  Alternatively, let us consider a case where the steps shown in FIGS. 2D and 2K and the steps shown in FIGS. 2E and 2L are not performed when a back-illuminated solid-state imaging device is manufactured. In this case, since each filter layer is formed with a uniform thickness, for example, a solid-state imaging device having a structure as shown in FIG. 5 or FIG. 6 is manufactured.

  On the other hand, in the embodiment, in the steps shown in FIGS. 2D and 2K and the steps shown in FIGS. 2E and 2L, for example, the edge of each green layer including the green layer 40g1i. And the edge of each red layer including the red layer 40r1i are selectively thinned. Thereby, for example, a color filter layer 40g1 including a main body portion 40g11 having a thickness Dg11 and an edge portion 40g12 having a thickness Dg12 thinner than the thickness Dg11 is formed. At the same time, for example, a color filter layer 40r1 including a main body portion 40r11 having a thickness Dr11 and an edge portion 40r12 having a thickness Dr12 thinner than the thickness Dr11 is formed. Further, a groove extending in a lattice shape is formed between the main body portion of each green color filter layer and the main body portion of each red color filter layer (see FIG. 2L). 2 (f) and 2 (m), for example, a blue color filter is formed in the region corresponding to the photoelectric conversion portion 11b on the back surface 10b side of the semiconductor substrate 10, that is, on the surface of the planarization layer 20 and the groove. Layer 40b1 and the like are formed. Thereby, the light reduction layer (henceforth a 1st light reduction layer) containing edge 40g12 covered with edge 40b12 and edge 40b12 can be formed, for example. In addition, for example, a light-reducing layer (hereinafter referred to as a second light-reducing layer) including the extending part 40b13 and the edge part 40g12 and the edge part 40r12 covered by the extending part 40b13 can be formed.

  Furthermore, in the embodiment, in the steps shown in FIGS. 2G and 2N, the planarization layer 30 that covers the plurality of color filter layers in which the level difference in the boundary region is significantly reduced is formed. Thereby, as described above, the thickness D30 for providing the flat surface on which the microlens is to be disposed can be significantly reduced (see FIG. 1-1A). As a result, for example, it is easy to form the microlenses MLg and MLb on the surface of the planarizing layer 30 so that the distance between the microlenses MLg and MLb and the photoelectric conversion units 11g and 11b is reduced.

  Note that the backside illumination type solid-state imaging device 1j shown in FIGS. 3 (g) and 3 (n) has a blue color filter layer and a red color as shown in FIGS. 3 (f) and 3 (m). The structure which replaced the filter layer may be sufficient. Even in this case, optical color mixing can be reduced in the backside illumination type solid-state imaging device 1j. For example, since the layer on the semiconductor substrate 10 side in the light reduction layer becomes an edge portion in the green color filter layer 40g1 or the blue color filter layer 40b1j, for example, optical mixing of short to medium wavelength light in the visible region is effectively performed. Can be reduced. Further, for example, the opening area of the red color filter layer 40r1j can be larger than the opening area of the green color filter layer 40g1, and can be larger than the opening area of the blue color filter layer 40b1j. As a result, for example, it is possible to suppress the red light receiving sensitivity from being weaker than that of blue and green, and to equalize the blue and green light receiving sensitivities and the red light receiving sensitivity.

  Further, in the manufacturing method of the backside illumination type solid-state imaging device 1j, in the steps shown in FIGS. 3D and 3K, the edge of each green layer including the green layer 40g1i and the blue color are formed by, for example, photolithography. A sacrificial film pattern 70j that selectively exposes the edge of each blue layer including the layer 40b1ji is formed. In the steps shown in FIGS. 3E and 3L, etch back processing is performed to etch the entire surface until the sacrificial film pattern 70j is completely removed. That is, in the steps shown in FIGS. 3D and 3K and the steps shown in FIGS. 3E and 3L, for example, the edge of each green layer including the green layer 40g1i and the blue layer 40b1ji are included. The edge of each blue layer is selectively thinned. Thereby, for example, the color filter layer 40g1 is formed and the color filter layer 40b1j is formed. Further, a groove extending in a lattice shape is formed between the main body portion of each green color filter layer and the main body portion of each blue color filter layer (see FIG. 3L). 3F and 3M, in the region corresponding to the photoelectric conversion portion 11r on the back surface 10b side of the semiconductor substrate 10, that is, the surface of the planarization layer 20, and the groove, for example, the red color filter layer 40r1j Form.

  Alternatively, as shown in FIGS. 4F and 4M, the backside illumination type solid-state imaging device 1k shown in FIGS. 4G and 4N has the blue color filter layer and the green color in the embodiment. The structure which replaced the filter layer may be sufficient. Even in this case, optical color mixing can be reduced in the backside illumination type solid-state imaging device 1k. For example, since the layer on the semiconductor substrate 10 side in the light reduction layer becomes an edge portion in, for example, the red color filter layer 40r1 or the blue color filter layer 40b1k, optical color mixing of short / long wavelength light in the visible region is effectively performed. Can be reduced. Further, for example, the opening area of the green color filter layer 40g1k can be made larger than the opening area of the red color filter layer 40r1, and can be made larger than the opening area of the blue color filter layer 40b1k. As a result, for example, it is possible to suppress the green light receiving sensitivity from being weaker than that of blue / red, and to equalize the blue light receiving sensitivity and the green light receiving sensitivity.

  Further, in the manufacturing method of the backside illumination type solid-state imaging device 1k, in the steps shown in FIGS. 4D and 4K, the edge of each red layer including the red layer 40r1i and the blue layer are formed by, for example, photolithography. A sacrificial film pattern 70k that selectively exposes the edge of each blue layer including the layer 40b1ki is formed. In the steps shown in FIGS. 4E and 4L, etch back processing is performed to etch the entire surface until the sacrificial film pattern 70k is completely removed. That is, in the steps shown in FIGS. 4D and 4K and the steps shown in FIGS. 4E and 4L, for example, the edge of each red layer including the red layer 40r1i and the blue layer 40b1ki are included. The edge of each blue layer is selectively thinned. Thereby, for example, the color filter layer 40r1 and the color filter layer 40b1k are formed. Further, a groove extending in a lattice shape is formed between the main body portion of each red color filter layer and the main body portion of each blue color filter layer (see FIG. 4L). 4F and 4M, in the region corresponding to the photoelectric conversion portion 11g on the back surface 10b side of the semiconductor substrate 10, that is, the surface of the planarization layer 20, and the groove, for example, a green color filter layer 40g1k Form.

  1, 1j, 1k solid-state imaging device, 10 semiconductor substrate, 10a front surface, 10b back surface, 11b, 11g, 11r photoelectric conversion part, 40b1, 40b1j, 40b1k, 40g1, 40g1k, 40g2, 40r1, 40r1j color filter layer, 40b1ji, 40b1ki , 40g1i, 40r1i layer, 40b11, 40g11, 40r11 body part, 40b12, 40g12, 40r12 edge part, 40b13 extension part, CFA color filter array, MLA micro lens array

Claims (6)

A back-illuminated solid-state imaging device,
A semiconductor substrate having a surface on which a plurality of photoelectric conversion units including a first photoelectric conversion unit and a second photoelectric conversion unit adjacent to the first photoelectric conversion unit are disposed, and a back surface opposite to the surface; ,
A first color filter layer disposed on the back side of the first photoelectric conversion unit so that light of the first color is incident on the first photoelectric conversion unit;
A second color filter disposed adjacent to the first color filter layer on the back side of the second photoelectric conversion unit so that light of the second color is incident on the second photoelectric conversion unit. Layers,
With
The first color filter layer includes
A body portion having a first thickness;
An edge portion disposed around the body portion and having a second thickness less than the first thickness;
Including
The solid-state imaging device, wherein the second color filter layer covers the edge in a boundary region with the first color filter layer. The second color filter layer includes
A second body portion having a third thickness;
A second edge disposed around the second body portion and having a fourth thickness less than the third thickness;
Including
The edge of the first color filter layer and the second edge of the second color filter layer overlap in a boundary region between the first color filter layer and the second color filter layer. The solid-state imaging device according to claim 1, wherein: The second edge and the edge covered by the second edge function as a light reducing layer for defining an opening region;
The solid-state imaging device according to claim 2, wherein an opening area of the second color filter layer is larger than an opening area of the first color filter layer. The plurality of photoelectric conversion units further include a third photoelectric conversion unit adjacent to the first photoelectric conversion unit in a direction intersecting with a direction adjacent to the second photoelectric conversion unit,
The solid-state imaging device is disposed adjacent to the first color filter layer on the back surface side of the third photoelectric conversion unit so that the third color light is incident on the third photoelectric conversion unit. A third color filter layer,
The third color filter layer includes
A third body having a fifth thickness;
A third edge disposed around the third body portion and having a sixth thickness less than the fifth thickness;
Including
The second color filter layer further includes an extending portion that covers both the edge portion and the third edge portion in a boundary region between the first color filter layer and the third color filter layer. The solid-state imaging device according to claim 2, wherein the solid-state imaging device is provided. A method of manufacturing a back-illuminated solid-state imaging device,
Forming a plurality of photoelectric conversion units including a first photoelectric conversion unit and a second photoelectric conversion unit adjacent to the first photoelectric conversion unit on a surface side in the semiconductor substrate;
A first layer to be a first color filter layer having a spectral transmittance peak in the wavelength region of the first color is formed in a region corresponding to the first photoelectric conversion unit on the back surface side of the semiconductor substrate. And a process of
The first color filter layer including a main body portion having a first thickness and an edge portion disposed around the main body portion and having a second thickness smaller than the first thickness is formed. And selectively thinning the edge of the first layer;
A second color filter layer having a spectral transmittance peak in the wavelength region of the second color in a region corresponding to the second photoelectric conversion unit on the back surface side of the semiconductor substrate, and the first color filter layer A step of covering the edge in the boundary region with
A method for manufacturing a solid-state imaging device. Forming a planarization layer covering the first color filter layer and the second color filter layer;
Forming a first microlens for condensing on the first photoelectric converter and a second microlens for condensing on the second photoelectric converter on the surface of the planarizing layer; When,
The method of manufacturing a solid-state imaging device according to claim 5, further comprising:

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