JP2005294647A - Solid state image pickup apparatus and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid state image pickup apparatus capable of preventing the generation of color mixing due to oblique light. <P>SOLUTION: A plurality of light receiving elements 2 are formed like a matrix on a light receiving area regulated on the main surface of a semiconductor substrate 1. A light shielding film 3 is formed on the upper layer of the light receiving area, and has a plurality of aperture areas 4 corresponding to respective light receiving elements 2. A color filter 6 is formed on the upper layer of each aperture area 4 to transmit only light having a prescribed color to the corresponding aperture area 4. A light shielding wall 7 divides mutually adjacent color filters 6 by its wall surfaces. The wall surfaces of the light shielding walls 7 exist in a continued state between the lower layer side main surface of the color filter 6 arranged on the lowermost layer and the upper layer side main surface of the color filter 6 arranged on the uppermost layer, at least in a plurality of the color filters 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device, and more specifically, relates to a solid-state imaging device including a color filter.

  Conventionally, as a solid-state imaging device, there is a CCD in which a color filter as shown in FIG. 11 is formed. Hereinafter, a conventional solid-state imaging device will be described with reference to FIG.

  The solid-state imaging device illustrated in FIG. 11 includes a semiconductor substrate 101, a photodiode 102, a light shielding film 103, an opening 104, a transparent film 105, a color filter 106, a planarizing film 108, and an on-chip microlens 109.

  A photodiode 102 is formed on the semiconductor substrate 101. The light shielding film 103 is formed so as to have an opening 104 in a region on the photodiode 102. A transparent film 105 is formed on the light shielding film 103. A color filter 106 is formed in a predetermined arrangement on the transparent film 105 so as to correspond to each photodiode 102. Specifically, a green color filter 106a is formed in a region above a plurality of photodiodes 102 formed in a matrix at equal intervals, for example, in a checkered pattern, and in a region other than the green color filter 106a. Red and Blue color filters 106b and c are alternately formed. Note that color filters made of Cyan, Yellow, Magenta, Green, White, and the like may be formed so as to correspond to the light receiving element regions in a predetermined arrangement.

  A planarizing film 108 is formed on the color filter 106. On-chip microlenses 109 are formed on the planarizing film 108 so as to correspond to the photodiodes 102.

  As described above, in the solid-state imaging device shown in FIG. 11, color images can be captured by forming the color filter 106 on-chip on the photodiode 102 so as to correspond to the opening 103 of the light shielding film 103. .

  However, in the solid-state imaging device shown in FIG. 11, after the light β (hereinafter referred to as oblique light) β incident on the solid-state imaging device is transmitted through the color filter 106 b of another color formed on the adjacent pixel. There is a problem in that the light enters the photodiode 102 and color mixing occurs.

  Therefore, there is a solid-state imaging device shown in FIG. 12 that can prevent color mixture due to oblique light. FIG. 12 is a diagram illustrating a cross-sectional structure of the solid-state imaging device.

The solid-state imaging device shown in FIG. 12 is obtained by providing black filters 110a, b, and c with anti-dye films 111a and 111b with respect to the solid-state imaging device of FIG. Thus, by newly providing the black filters 110a, b and c, the oblique light γ is shielded by the black filters 110a, b and c as shown in FIG. As a result, the incident light enters the photodiode 102 without fading the color filter 106 formed corresponding to the opening 104 of the adjacent pixel. Thereby, the problem of color mixing in the solid-state imaging device is reduced. (See Patent Document 1).
Japanese Patent Publication No. 8-8344

  However, the solid-state imaging device shown in FIG. 12 has a problem that color mixing occurs when oblique light having a large angle is incident. This will be described in detail below.

  In the solid-state imaging device shown in FIG. 12, the black filter 110 has a three-layer structure. Therefore, a gap exists between the black filters 110 adjacent in the vertical direction as shown in FIG. Therefore, the oblique light δ incident at a large angle with respect to the normal line of the main surface of the semiconductor substrate 101 passes through a gap between the black filters 110 as shown in FIG. As a result, the oblique light δ enters after passing through the color filter 106 of another color formed on the adjacent pixel, or directly enters the photodiode without passing through any color filter. That is, color mixing occurs. In addition, when the conditions that the film thickness of the dye-proof film 111 is sufficiently thin and the width of the black filter 110 is sufficiently large cannot be satisfied, a problem of color mixing occurs particularly noticeably.

  Therefore, an object of the present invention is to provide a solid-state imaging device that can more effectively prevent color mixing due to oblique light, and to provide a manufacturing method for manufacturing the solid-state imaging device.

  A solid-state imaging device according to the present invention includes a semiconductor substrate, a plurality of light receiving elements formed in a matrix in a light receiving region defined on a main surface of the semiconductor substrate, and a light receiving region formed on an upper layer of the light receiving region. A plurality of light-shielding films having a plurality of opening regions corresponding to each of the plurality of light-receiving films, and a plurality of light-transmitting films that are formed in an upper layer of each opening region and transmit only light having a predetermined color among incident light to the corresponding opening regions. A color filter and a light shielding wall that partitions between adjacent color filters by a wall surface are provided. The wall surface of the light shielding wall is continuous between at least the main surface on the lower layer side of the color filter located on the lowermost layer and the upper surface on the upper layer side of the color filter located on the uppermost layer among the plurality of color filters. Exists in a state.

  Moreover, the shape of the light shielding wall may have a lattice shape when projected onto the main surface of the semiconductor substrate.

  The light shielding wall may have a stripe shape when projected onto the main surface of the semiconductor substrate.

  Moreover, the shape of the light shielding wall may have a mesh shape when projected onto the main surface of the semiconductor substrate.

  In addition, the light shielding walls are formed such that the midpoints of those facing each other across the opening region are shifted in the center direction of the light receiving region with respect to the center of the opening region. The amount of deviation between the midpoint of the opposing light shielding walls and the center of the opening area may be a size corresponding to the distance from the center of the light receiving area.

  Further, the amount of deviation between the midpoint of the light shielding patterns facing each other across the opening area and the center of the opening area may increase as the distance from the center of the light receiving area increases.

  The solid-state imaging device according to the present invention may further include a plurality of microlenses formed on the upper layer of each color filter so as to correspond to each color filter. In this case, it is desirable that the light shielding wall has a structure in which the thickness of the wall becomes thinner as it goes from the lower layer to the upper layer.

  In addition, the solid-state imaging device according to the present invention may further include a light shielding wall disposed in a lower layer of the region where the light shielding wall is formed and in an upper layer region of the light shielding film.

  Further, the light shielding wall may be formed of a material having a property of absorbing light.

  The light shielding wall may be formed of a material having a property of reflecting light.

  The present invention is directed not only to a solid-state imaging device but also to a method for manufacturing the solid-state imaging device. Specifically, in the light receiving region defined on the semiconductor substrate, a plurality of light receiving elements are formed in a matrix, and a light shielding film having an opening region corresponding to each light receiving element is formed in an upper layer of the light receiving region, A plurality of color filters that transmit only light having the above colors are formed in the upper layer of each opening region, a transparent film is formed between and above the plurality of color filters, and each color filter is formed in the upper layer of the transparent film. A protective mask having an opening area in the shape of partitioning is formed, and the transparent film between the color filters is etched away using the protective mask to form a groove for partitioning between the color filters. The light shielding wall may be formed by embedding a light shielding material.

  Further, in the step of forming the light shielding wall, a mask pattern in which a photosensitive and light shielding resin is applied to the transparent film and the groove, and the exposure amount changes according to the distance from the center line of the groove. Is used to perform exposure processing on the resin, and the resin exposed in the exposure processing is removed by development processing, thereby forming a light-shielding wall whose wall thickness decreases from the lower layer to the upper layer. You may do it.

  Further, in the step of forming the light shielding wall, a light shielding resin may be applied to the transparent film and the groove, and the light shielding resin protruding from the groove may be removed by an etch back method.

  According to the present invention, the light blocking wall includes at least a main surface on the lower layer side of the color filter located in the lowermost layer and a main surface on the upper layer side of the color filter located in the uppermost layer among the plurality of color filters. Exists in a continuous state. As a result, oblique light is prevented from entering through the gap between the light shielding walls.

  The light shielding walls are formed such that the midpoints of the light shielding walls facing each other across the opening region are shifted in the center direction of the light receiving region with respect to the center of the opening region. The amount of deviation between the midpoint of the light shielding walls facing each other across the opening area and the center of the opening area is a size corresponding to the distance from the center of the light receiving area. Therefore, the difference in light receiving sensitivity between the central portion of the light receiving region and the peripheral region other than the central portion can be reduced.

  In addition, according to the present invention, the light shielding wall has a structure in which the thickness of the wall decreases as it goes from the lower layer to the upper layer, so that the light transmitted through the microlens is more efficiently collected in the light receiving element.

  Further, according to the present invention, a new light shielding wall is disposed in a lower layer of the region where the light shielding wall is formed and in an upper layer region of the light shielding film. This more effectively prevents oblique light from entering the light receiving element.

  Moreover, according to the method for manufacturing a solid-state imaging device according to the present invention, the solid-state imaging device according to the present invention can be manufactured.

(First embodiment)
A solid-state imaging device according to an embodiment of the present invention will be described below with reference to the drawings. Here, FIG. 1 is a diagram showing a cross-sectional structure of the solid-state imaging device according to the present embodiment.

  As shown in FIG. 1, the pixel of the solid-state imaging device according to the present embodiment includes a semiconductor substrate 1, a photodiode 2, a light shielding film 3, an opening 4, a transparent film 5, a color filter 6, a light shielding wall 7, and a planarization film. 8 and an on-chip microlens 9. The solid-state imaging device according to the present embodiment is provided with a light shielding wall 7 penetrating from the lower surface to the upper surface of the color filter 6, so that light β (hereinafter referred to as “light β”) incident from an adjacent pixel as shown in FIG. (Referred to as oblique light) is prevented from entering the photodiode 2.

  In the light receiving region defined on the semiconductor substrate 1, a plurality of photodiodes 2 are formed in a matrix at equal intervals. The photodiode 2 generates a signal charge having a charge amount corresponding to the intensity reaching the photodiode 2 in the light α incident from above in FIG. Further, a light shielding film 7 is formed so as to cover the space between the plurality of photodiodes 2. The light shielding film 7 is a film for preventing light from entering between the photodiode 2 and the photodiode 2. An opening 4 is formed in a part of the light shielding film 7. The openings 4 are formed to allow light to enter the photodiodes 2, and are formed at regular intervals in a matrix form immediately above each photodiode 2.

  A transparent film 5 is formed on the light shielding film 3 and the opening 4. The transparent film 5 has electrical insulation, and is formed of, for example, a BPSG film formed by a CVD method or a resin film formed by coating. A color filter 6 is formed in a region that coincides with the region in which the opening 4 is formed when viewed from above with respect to the main surface of the semiconductor substrate 1 and in the upper layer of the transparent film 5. The color filters 6 are arranged in a matrix so as to correspond to the photodiodes 2 in a predetermined arrangement. Here, FIG. 2 is a diagram showing an example of the arrangement of the color filters 6. 2 is a diagram when the solid-state imaging device is viewed from above with respect to the main surface of the semiconductor substrate 1. FIG.

  As shown in FIG. 2, the color filter 6 transmits only light of a specific color from the incident light to the photodiode 4, and there are a color filter 6a, a color filter 6b, and a color filter 6c. Examples of the three types of color filters 6 include a filter that transmits Green light, a filter that transmits Red light, and a filter that transmits Blue light. For example, the color filter 6a is a green color filter, the color filter 6b is a red color filter, and the color filter 6c is a blue color filter.

  The color filter 6b is formed every other row in one column. Similarly, the color filter 6c is formed every other row in one column. The column in which the color filter 6b is formed and the column in which the color filter 6c is formed are alternately arranged. The color filter 6b and the color filter 6c are formed in a state where they are shifted one line so as not to contact each other. And the color filter 6a is formed in the part in which the color filter 6b and the color filter 6c are not formed. That is, the color filter 6a is formed in a so-called checkered pattern.

  The light shielding wall 7 is made of a material having a light shielding property, and plays a role of preventing color mixing caused by the oblique light β in FIG. 1 entering the photodiode 4. The light shielding wall 7 is formed in the upper layer of the light shielding film 3 so that the color filters 6 adjacent to each other are partitioned by a wall surface. The wall surface of the light shielding wall 7 (the side surface of the light shielding wall 7 in FIG. 1) needs to exist in a continuous state at least between the main surface on the lower layer side and the main surface on the upper layer side of the color filter 6. is there. Thereby, oblique light can be effectively prevented from entering the photodiode 4. Not all color filters 6 are formed on the same plane as shown in FIG. 1, but color filters may exist in a plurality of layers as shown in FIG. In this case, the light-shielding wall 7 is between the main surface on the lower layer side of the color filter located in the lowermost layer and the main surface on the upper layer side of the color filter located in the uppermost layer among the plurality of color filters 6. Must exist in a continuous state.

  On the upper layer of the color filter 6 and the light shielding wall 7, a planarizing film 8 having light transmittance is formed. On-chip microlenses 9 are formed in a matrix on the planarizing film 8 so as to correspond to the photodiodes 2. The on-chip microlens 9 collects light α incident from above on the photodiode 2.

  As described above, according to the solid-state imaging device according to the present embodiment, color mixing can be prevented more effectively than the conventional solid-state imaging device by having the structure shown in FIG. This will be described below with reference to FIG.

  In the conventional solid-state imaging device shown in FIG. 12, the black filter 110 has a multilayer structure. Therefore, there is a gap due to the stain-proof film 111 between the black filters 110 adjacent in the vertical direction. Therefore, as shown in FIG. 12, when oblique light δ having a large angle with respect to the normal line of the main surface of the semiconductor substrate 101 is incident, there is a problem that color mixing occurs.

  In contrast, in the solid-state imaging device according to the present embodiment, the light shielding wall 7 is disposed between the upper surface and the lower surface of the color filter 6 without interruption as shown in FIG. For this reason, there is no gap due to the antifouling film 111 present in FIG. As a result, the oblique light β having a large angle with respect to the main surface of the semiconductor substrate 101 is blocked by the light shielding wall 7. That is, the solid-state imaging device according to the present embodiment can prevent color mixing more effectively than the conventional solid-state imaging device.

  In the solid-state imaging device according to the present embodiment, as shown in FIG. 1, the light shielding wall 7 has a rectangular cross-sectional structure, but the structure of the light shielding wall 7 is not limited thereto. The light shielding wall 7 may have a cross-sectional structure as shown in FIGS. 3 and 4, for example. Specifically, the light shielding wall 7 shown in FIGS. 3 and 4 has a shape in which the thickness of the wall in the vicinity of the end portion in the upper layer direction becomes thinner as it goes from the lower layer to the upper layer. Thereby, the solid-state imaging device can efficiently collect the light transmitted through the on-chip microlens 9 in the photodiode while preventing color mixing.

  As shown in FIG. 5, in the solid-state imaging device according to the present embodiment, a light shielding wall 10 may be provided in addition to the light shielding wall 7. Specifically, a new light shielding wall 10 may be provided in the lower layer region of the light shielding wall 7 and in the upper layer region of the light shielding film 3. Thereby, color mixing is prevented more effectively.

(Second Embodiment)
A solid-state imaging device according to the second embodiment of the present invention will be described below with reference to the drawings. In the solid-state imaging device according to the first embodiment, the pixels having the structure shown in FIG. 1 are formed over the entire light receiving region, whereas in the solid-state imaging device according to the present embodiment, depending on the position in the light receiving region. The pixel structure is different. Here, FIG. 6 is a diagram illustrating a cross-sectional structure of the solid-state imaging device according to the present embodiment. Specifically, FIG. 6A is a diagram illustrating a cross-sectional structure of the solid-state imaging device in the vicinity of the left end of the light receiving region. FIG. 6B is a diagram illustrating a cross-sectional structure of the solid-state imaging device in the vicinity of the center of the light receiving region. FIG. 6C is a diagram illustrating a cross-sectional structure of the solid-state imaging device in the vicinity of the right end of the light receiving region.

  The solid-state imaging device according to this embodiment includes a semiconductor substrate 1, a photodiode 2, a light shielding film 3, an opening 4, a transparent film 5, a color filter 6, a light shielding wall 7, a planarizing film 8, and an on-chip microlens 9. . Since the roles of all these components are the same as those in the first embodiment, description thereof is omitted. Further, the positional relationship among the semiconductor substrate 1, the photodiode 2, the light shielding film 3, the transparent film 5, the color filter 6 and the planarizing film 8 is the same as that in the first embodiment, so that the description thereof is omitted.

  Hereinafter, the positional relationship among the opening 4, the light shielding wall 7, and the on-chip microlens 9, which is the difference between the present embodiment and the first embodiment, will be described with reference to FIG. 6.

  As for the light shielding wall 7 of the solid-state imaging device according to the present embodiment, the midpoints of the light shielding walls 7 facing each other with the opening 4 interposed therebetween are shifted from the center of the opening 4 in the center direction of the light receiving region. It is formed. Specifically, in the pixel at the left end of the light receiving region, as shown in FIG. 3A, the light shielding wall 7 is disposed so as to be shifted to the right as compared with the light shielding wall 7 shown in FIG. The Further, in the pixel at the right end of the light receiving region, as shown in FIG. 3C, the light shielding wall 7 is arranged so as to be shifted to the left as compared with the light shielding wall 7 shown in FIG. The central pixel in the light receiving region has the same configuration as that in FIG.

  Further, in the pixel at the upper end of the light receiving region, the light shielding wall 7 is disposed so as to be shifted downward as compared to the light shielding wall 7 in FIG. 1 (not shown). In the pixel at the lower end of the light receiving region, the light shielding wall 7 is arranged so as to be shifted upward as compared to the light shielding wall 7 of FIG. 1 (not shown).

  Here, the magnitude | size of the shift | offset | difference of the light-shielding wall 7 is demonstrated using FIG. FIG. 7 is a diagram showing the positional relationship between the opening 4 and the light shielding wall 7. For simplification of description, the light receiving region has a matrix structure of 5 pixels × 5 pixels.

  As shown in FIG. 7, the openings 4 are formed in the light shielding film 3 in a matrix at equal intervals. Further, a light shielding wall 7 is formed on the light shielding film 3. The amount of deviation between the midpoint of the light shielding walls 7 facing each other across the opening 4 and the center of the opening 4 increases as the distance from the center of the light receiving region increases. In addition, the black circle in FIG. 7 is the point which showed the midpoint of light-shielding walls 7 which mutually oppose. Further, the black square in FIG. 7 is a point indicating the center of the opening 4. In this way, by arranging the light shielding wall 7 so as to be shifted toward the center of the pixel, the incident light at a position away from the center of the light receiving region can be efficiently collected in the photodiode 2. Become.

  As described above, according to the solid-state imaging device according to the present embodiment, it is possible to prevent oblique light from entering the photodiode 2 as in the solid-state imaging device according to the first embodiment, and between pixels in the light receiving region. Variation in light receiving sensitivity can be suppressed.

  In the solid-state imaging device according to the present embodiment, the amount of deviation of the light shielding wall 7 increases as the distance from the center of the light receiving region increases. However, the amount of deviation of the light shielding wall 7 is not limited thereto. For example, in the solid-state imaging device according to the present invention, the light-shielding wall 7 existing within a predetermined distance from the center of the light receiving region is not displaced and is present at a location away from the center of the light receiving region. The light shielding wall 7 may have a shift amount corresponding to the distance from the center of the light receiving region.

  In the first and second embodiments, it is desirable that the light shielding wall 7 be formed in a lattice shape, a stripe shape, or a mesh shape when the semiconductor substrate 1 is viewed from above.

  Moreover, in the solid-state imaging device according to the first and second embodiments, the light shielding wall 7 may be formed of a material that does not transmit light. Therefore, the material may have a property of absorbing light or a property of reflecting light. The material may have both of these properties. In addition, as a material which has the characteristic which absorbs light, the resin which contains the resin which has black, the inorganic film | membrane which has black, the metal which has black, or a black granule in a certain ratio or more is mentioned. Moreover, as a material which has the characteristic which reflects light, the inorganic film | membrane which contains a metal or resin which contains a metal particle in a ratio more than a fixed ratio, or a metal particle in a ratio more than fixed is mentioned, for example. Examples of the material having both characteristics of absorbing and reflecting light include a black resin containing metal particles at a certain ratio or a black inorganic film containing metal particles at a certain ratio. It is done.

  In the first and second embodiments, the color of light transmitted through the color filter 6 is Green, Red, and Blue. However, the color of light transmitted through the color filter is not limited to this. For example, the color of light transmitted through the color filter 6 may be Cyan, Yellow, Magenta, Green, White, or the like.

  In the first and second embodiments, the CCD type solid-state imaging device has been described. However, the solid-state imaging device according to the present invention is also effective in amplification type solid-state imaging devices such as a MOS type and an AMI type. Needless to say.

(Method for manufacturing solid-state imaging device)
Hereinafter, a method for manufacturing a solid-state imaging device according to the present invention will be described with reference to the drawings. Here, as an example of the solid-state imaging device according to the present invention, a method for manufacturing the solid-state imaging device shown in FIG. 3 will be described. 8 to 10 are diagrams showing a cross-sectional structure of the solid-state imaging device in each process of manufacturing the solid-state imaging device shown in FIG.

  First, as shown in FIG. 8A, the photodiodes 2 are formed in the light receiving region of the semiconductor substrate 1 so as to form a matrix at equal intervals. Next, as shown in FIG. 8B, a light shielding film 3 having a light shielding property is formed so as to cover a plurality of the photodiodes 2. Specifically, a W (tungsten) thin film is formed by a PVD method or a CVD method. Thereafter, the W thin film located on the upper portion of the photodiode 2 is selectively removed by dry etching. As a result, the light shielding film 3 as shown in FIG. 8B and the opening 4 are formed.

  Next, as shown in FIG. 8C, a transparent film 5 is formed on the light shielding film 3 and the opening 4. For example, the transparent film 5 is deposited by a CVD method using a BPSG film. Thereafter, the BPSG film is reflowed by heat treatment to flatten the surface. Thereby, the transparent film 5 is formed.

  Next, as shown in FIG. 8D, the color filter 6 is formed in the region above the transparent film 5 and above the opening 4. The color filter 6 is formed in a matrix so as to correspond to each photodiode 2 in a predetermined arrangement. The color filter 6 is a dyeing method for obtaining a desired colored pattern by a dyeing process after forming a pattern to be dyed, or a color resist method for obtaining a colored pattern by a photolithography method using a photosensitive material containing a dye or a pigment. And the like.

  Next, in order to improve the flatness of the surface after the color filter 6 is formed, a planarization film 17 is formed on the color filter 6 as shown in FIG. The planarizing film 17 is made of, for example, a transparent resin material.

  Next, as shown in FIG. 9 (f), a resist pattern 16 having an opening region in the shape of partitioning between the color filters 6 is formed on the planarizing film 17 by photolithography.

  Next, dry etching using CF-based gas or oxygen gas is performed, and the end portions of the planarizing film 17 and the color filter 6 existing below the opening region of the resist pattern 16 are formed using the resist pattern 16 as a protective mask. The groove 20 is formed by selective removal. In the dry etching process, the planarizing film 17 is removed so that the bottom of the groove 20 reaches the main surface on the lower layer side of the color filter 6. The width of the groove 20 can be determined according to the light shielding ability required for the light shielding wall 7. For example, when the light shielding property is increased, the width of the groove 20 is thick, and when the light shielding property may be weak, the groove 20 may be formed thin. Thereafter, as shown in FIG. 9G, the resist pattern residue is removed using a resist stripping solution made of an organic solvent.

  Next, as shown in FIG. 10H, a light shielding material is applied so as to fill the groove 20 to form the light shielding wall film 18. The material used for the light shielding wall film 18 is desirably a resin having light shielding properties and photosensitivity.

  Next, as shown in FIG. 10I, a part of the light shielding wall film 18 is removed by photolithography to expose the planarizing film 17, and the thickness of the wall in the vicinity of the end on the upper layer side. As a result, the light shielding wall 7 is formed which becomes thinner as it goes from the lower layer to the upper layer. Specifically, first, an exposure process is performed using a mask pattern 19 whose exposure amount changes according to the distance from the center line of the groove 20. Next, the exposed portion of the light shielding film 18 is removed by developing. In the present embodiment, the mask pattern 19 having an exposure amount that increases as the distance from the center of the groove 20 increases.

  Next, as shown in FIG. 10 (j), in order to improve the flatness of the surface on the planarizing film 17 and the light shielding wall 7, for example, a transparent film is used by using the same transparent resin material as the planarizing film 17. The additional formation. Thereby, the planarizing film 8 is formed.

  Finally, an on-chip microlens 8 is formed on the planarizing film 8. Specifically, the on-chip microlens 8 is formed by heat-melting transparent resin or resist heat reflow transfer on the upper part thereof. Through the steps as described above, a solid-state imaging device having a structure as shown in FIG. 3 is completed.

  In the solid-state imaging device according to the present embodiment, when the light shielding wall 7 is formed, a black pattern having a light shielding property may be formed by photolithography and a staining method after applying a film having no light shielding property.

  In the solid-state imaging device according to the present embodiment, in forming the light shielding wall 7, after filling the groove 20 by applying a resin containing black resin material or metal particles at a certain ratio, The light shielding wall 7 may be formed by a method of exposing the planarization film 17 by an etch back method or a CMP method. However, in this case, the light shielding film 7 has a shape as shown in FIG.

  As a method of processing the light shielding wall film 18 into the light shielding wall 7, a resist pattern having an opening region having a shape partitioning each of the color filters 6 is formed by photolithography, and then the resist pattern is used as a protective mask. Alternatively, the light shielding wall film 18 existing under the region where the resist pattern is not formed may be selectively removed by dry etching or wet etching.

  By controlling the anisotropy and isotropy during etching, the light shielding wall 7 can be processed so as to have a structure in which the wall thickness decreases in the vertical direction from the lower layer to the upper layer direction. . Specifically, after the light shielding wall film 18 having a certain thickness is removed by anisotropic etching, the remaining light shielding wall film 18 is exposed so that the planarization film 17 is exposed by isotropic etching. You may form by removing.

  In addition, as an example in the case where the light shielding wall 7 is processed so that the cross-sectional structure in the vertical direction has a structure in which the wall thickness decreases from the lower layer toward the upper layer, a transparent film is added again after the light shielding wall 7 is formed. The example of the manufacturing method to form was demonstrated and demonstrated. However, when the unevenness of the surface after forming the light shielding wall 7 has sufficient flatness for forming the on-chip microlens 9, the additional formation of the transparent film after forming the light shielding wall 7 is omitted. May be.

The transparent film 5 formed on the light-shielding film 3 may be formed by forming a thin film having insulating properties and light transmittance, and then performing a planarization process on the thin film. In addition, as a method of forming a thin film having insulating properties and light transmittance, for example, a method of applying a resin system such as SOG, a method of depositing TEOS-based SiO ₂ / BPSG by a CVD method, or a bias high density plasma method And a method of depositing a SiO ₂ -based film by the above method. Further, as the planarization treatment, for example, an etch back or a CMP method can be given. Further, the planarizing film may be SiON instead of SiO ₂ .

  As a method of processing the light shielding wall 7 from the light shielding wall film 18, an example using a positive photoresist has been shown, but the same processing can be realized even with a negative resist.

  In the method for manufacturing the solid-state imaging device, the method for manufacturing the solid-state imaging device shown in FIG. 3 has been described. Here, when the solid-state imaging device shown in FIG. 1 is manufactured, the photolithography process of FIG. When the solid-state imaging device according to the second embodiment shown in FIG. 6 is manufactured, the opening area of the register pattern 16 formed in FIG. 9F is the opening 4 formed in the light shielding film 3. The midpoints of those facing each other across the gap must be shifted from the center of each opening 4 toward the center of the light receiving region. Note that the amount of deviation between the midpoint of the light shielding films 3 facing each other across the openings 4 and the center of each opening 4 increases as the distance from the center of the light receiving region increases. In this case, the on-chip microlens 9 is desirably formed at a position shifted in the center direction of the light receiving region with respect to the center of the opening 4 in accordance with the amount of shift of the light shielding wall 7.

  The solid-state imaging device according to the present invention has an effect of further preventing color mixing due to oblique light, and is useful as a solid-state imaging device including a color filter.

The figure which showed an example of the cross-section of the solid-state imaging device which concerns on the 1st Embodiment of this invention A diagram showing how the color filters are arranged The figure which showed the other example of the cross-section of the solid-state imaging device which concerns on the 1st Embodiment of this invention The figure which showed the other example of the cross-section of the solid-state imaging device which concerns on the 1st Embodiment of this invention The figure which showed the other example of the cross-section of the solid-state imaging device which concerns on the 1st Embodiment of this invention The figure which showed the cross-section of the solid-state imaging device concerning the 2nd Embodiment of this invention The figure which looked at the solid-state imaging device concerning a 2nd embodiment of the present invention from the upper part The figure which showed the cross-sectional structure at the time of manufacture of the solid-state imaging device concerning the 1st Embodiment of this invention The figure which showed the cross-sectional structure at the time of manufacture of the solid-state imaging device concerning the 1st Embodiment of this invention The figure which showed the cross-sectional structure at the time of manufacture of the solid-state imaging device concerning the 1st Embodiment of this invention A diagram showing a cross-sectional structure of a conventional solid-state imaging device A diagram showing a cross-sectional structure of a conventional solid-state imaging device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Photodiode 3 Light-shielding film 4 Opening part 5 Transparent film 6 Color filter 7 Light-shielding wall 8 Flattening film 9 On-chip microlens 10 Light-shielding wall 11 Dye-proof film 16 Resist pattern 17 Flattening film 18 Light-shielding wall film 19 Mask pattern 20 groove

Claims (14)

A semiconductor substrate;
In the light receiving region defined on the main surface of the semiconductor substrate, a plurality of light receiving elements formed in a matrix, and
A light shielding film formed in an upper layer of the light receiving region and having a plurality of opening regions corresponding to each of the light receiving elements;
A plurality of color filters that are formed in an upper layer of each of the opening regions and transmit only light having a predetermined color among incident light to the corresponding opening regions;
A light shielding wall that partitions the color filters adjacent to each other by a wall surface;
The wall surface of the light shielding wall is a continuous state between the lower principal surface of the color filter located in the lowermost layer and the upper major surface of the color filter located in the uppermost layer among the plurality of color filters. A solid-state imaging device, characterized in that:   The solid-state imaging device according to claim 1, wherein the shape of the light shielding wall has a lattice shape when projected onto the main surface of the semiconductor substrate.   The solid-state imaging device according to claim 1, wherein the shape of the light shielding wall has a stripe shape when projected onto the main surface of the semiconductor substrate.   2. The solid-state imaging device according to claim 1, wherein the light shielding wall has a mesh shape when projected onto a main surface of the semiconductor substrate. The light shielding wall is formed such that a midpoint between those facing each other across the opening region is shifted in a center direction of the light receiving region with respect to a center of the opening region,
The amount of deviation between the midpoint between the light shielding walls facing each other across the opening region and the center of the opening region is a size according to the distance from the center of the light receiving region, The solid-state imaging device according to claim 2.   6. The shift amount between the midpoint of the light shielding patterns facing each other across the opening region and the center of the opening region increases as the distance from the center of the light receiving region increases. Solid-state imaging device. In order to correspond to each of the color filters, further comprising a plurality of microlenses formed in the upper layer of each color filter,
2. The solid-state imaging device according to claim 1, wherein the light shielding wall has a structure in which the thickness of the wall becomes thinner from the lower layer to the upper layer.   2. The solid-state imaging device according to claim 1, further comprising a new light-shielding wall disposed in a lower layer of the region where the light-shielding wall is formed and in an upper layer region of the light-shielding film.   The solid-state imaging device according to claim 1, wherein the light shielding wall is formed of a material having a characteristic of absorbing light. The solid-state imaging device according to claim 1, wherein the light shielding wall is formed of a material having a property of reflecting light. Forming a plurality of light receiving elements in a matrix in a light receiving region defined on a semiconductor substrate;
Forming a light shielding film having an opening region corresponding to each of the light receiving elements in an upper layer of the light receiving region;
Forming a plurality of color filters that transmit only light having a predetermined color in an upper layer of each of the opening regions;
Forming a transparent film between and above the plurality of color filters;
Forming a protective mask having an opening region in a shape partitioning the color filters on the transparent film;
Using the protective mask, the transparent film between the color filters is etched away to partition the color filters, and the main surface of the color filter placed on the lowermost side of the color filters Forming a groove whose bottom is positioned on the lower layer side, and
And a step of forming a light shielding wall by embedding a light shielding material in the groove. The step of forming the light shielding wall includes:
Applying a photosensitive and light-shielding resin to the transparent film and the groove;
A step of performing an exposure process on the resin using a mask pattern in which an exposure amount changes according to a distance from a center line of the groove;
The step of forming a light-shielding wall in which the thickness of the wall decreases as it goes from the lower layer to the upper layer by removing a part of the resin exposed by the exposure process by a development process. Manufacturing method of solid-state imaging device. The step of forming the light shielding wall includes:
Applying a light-shielding resin to the transparent film and the groove;
The method for manufacturing a solid-state imaging device according to claim 11, further comprising: removing the light-shielding resin protruding from the groove by an etch back method. The step of forming the light shielding wall includes:
Applying a light-shielding resin to the transparent film and the groove;
Applying a resist material on the light-shielding resin;
Forming a resist pattern on the groove;
The method for manufacturing a solid-state imaging device according to claim 11, comprising: removing the light-blocking resin protruding from the groove by etching using the resist pattern as a protective mask.

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