Patent Publication Number: US-2009230490-A1

Title: Solid-state imaging device and method for manufacturing the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 on Patent Application No. 2008-65849 filed in Japan on Mar. 14, 2008, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a color solid-state imaging device and a method for manufacturing the same. More particularly, the present invention relates to a color solid-state imaging device having color filter layers which are made of a photosensitive resin, or the like, including dispersed therein a coloring agent such as a pigment, a dye, or the like, and a method for manufacturing the same. 
     A color solid-state imaging device includes color filter layers (pigment layers), each corresponding to a different photoelectric transducer, which are arranged in a predetermined pattern for obtaining color images (see, for example, Japanese Laid-Open Patent Publication No. 11-150252; hereinafter “Patent Document 1”). Each color filter layer used in a color solid-state imaging device is formed by applying, exposing, developing and curing a photosensitive resin, or the like, including dispersed therein a coloring agent such as a pigment, a dye, or the like, on a substrate. Referring to  FIGS. 15-20B , the structures of conventional solid-state imaging devices including color filter layers will be described. 
       FIG. 15  is a plan view showing color filter layers provided in a conventional solid-state imaging device as disclosed in Patent Document 1, for example, as viewed from the lens side. Typically, a single-chip color solid-state imaging device, which uses a color filter including color filter layers of three primary colors of light placed on a solid-state imaging device, often uses color filter layers arranged in a Bayer array. 
     As shown in  FIG. 15 , a color filter  20  includes green color filter layers  20 G arranged in a checker pattern, and includes blue color filter layers  20 B and red color filter layers  20 R alternating with each other by rows or by columns to fill the open spots in the checker pattern. In other words, a repetitive pattern of green, red, green, red, . . . , occurs in a row (e.g., a row along line XVIa-XVIa in  FIG. 15 ), and a repetitive pattern of blue, green, blue, green, . . . , occurs in the next row. Similarly, a repetitive pattern of green, red, green, red, . . . , occurs in a column, and a repetitive pattern of blue, green, blue, green, . . . , occurs in the next column. 
       FIGS. 16A to 17B  are schematic cross-sectional views showing a conventional solid-state imaging device as disclosed in Patent Document 1, wherein  FIGS. 16A and 17A  are cross-sectional views taken along line XVIa-XVIa in  FIG. 15 , and  FIGS. 16B and 17B  are cross-sectional views taken along line XVIb-XVIb in  FIG. 15 . 
     As shown in  FIGS. 16A to 17B , the conventional solid-state imaging device includes an N-type semiconductor substrate  11  and a P-type well layer  12  formed on the N-type semiconductor substrate  11 , with a plurality of photoelectric transducers  13  formed in an upper portion of the P-type well layer  12  for photoelectric conversion as an N-type semiconductor layer. A gate insulating film  14  is formed so as to cover the P-type well layer  12  and the photoelectric transducers  13 , and a transfer electrode  15  for transferring a signal is formed on the gate insulating film  14  between the photoelectric transducers  13 . An interlayer insulating film  16  is formed on the side surface and the upper surface of the transfer electrode  15  so that the transfer electrode  15  is covered by the interlayer insulating film  16 , and a light blocking film  17  is formed on the side surface and the upper surface of the interlayer insulating film  16  so that the interlayer insulating film  16  is covered by the light blocking film  17 . The light blocking film  17  is formed by tungsten, or the like, and serves to prevent unnecessary light from being incident on portions other than the photoelectric transducers  13 . A passivation film  18  is formed so as to cover the gate insulating film  14  and the light blocking film  17 . Since the layer underlying the passivation film  18  is not flat, the passivation film  18  is formed with depressed portions on the upper surface thereof. A first transparent flattening layer  19   a  is formed in the depressed portions of the passivation film  18 , and a second transparent flattening layer  19   b  of a thermosetting transparent resin is formed on the flattened upper surface of the passivation film  18  and the first transparent flattening layer  19   a . Moreover, the color filter  20  is formed on the second transparent flattening layer  19   b . The second transparent flattening layer  19   b  serves to improve the adhesion of the color filter  20  and also to reduce the development residue. The color filter  20  is a collection of color filter layers of predetermined pigments (green, red and blue) for different pixels, i.e., the green color filter layers  20 G, the red color filter layers  20 R and the blue color filter layers  20 B, wherein the color filter layers are arranged in an array as shown in  FIG. 15 . A third transparent flattening layer  19   c  is formed on the color filter  20 , and an array of microlenses  22  is formed on the third transparent flattening layer  19   c . Each microlens  22  is in a convex lens corresponding to the color filter layer and the photoelectric transducer  13  of one pixel, and serves to improve the efficiency in collecting light onto the photoelectric transducer  13  of the pixel. 
     In the conventional solid-state imaging device of Patent Document 1, the color filter  20  is formed as follows. That is, the green color filter layers  20 G, which account for the largest portion of the sensing area among the red, green and blue color filter layers, are formed on the flattening film  19   b  as the first layer of the color filter  20 . Therefore, since the green color filter layers  20 G have a large contact area with the underlying flattening film  19   b , the adhesion therebetween is improved and the exfoliation therebetween is prevented. Then, the second and third layers of the color filter  20 , e.g., the red color filter layers  20 R and the blue color filter layers  20 B, respectively, are formed as follows. That is, the red color filter layers  20 R or the blue color filter layers  20 B are formed so that the edge thereof overlaps the edge of the green color filter layers  20 G. Therefore, since not only the portion of the red color filter layers  20 R or the blue color filter layers  20 B in direct contact with the underlying layer, but also the overlapping portion is bonded, the adhesion is improved. In the color filter  20  with an overlap between edge portions, there is no gap between adjacent color filter layers, thereby increasing the area of the color filter  20  in direct contact with the underlying layer. The green color filter layer  20 G of each unit pixel has a larger area than the red color filter layer  20 R or the blue color filter layer  20 B to such an extent that there is no influence from adjacent pixels. Thus, the green color filter layer  20 G has an increased contact area with the underlying layer, thereby preventing the exfoliation and the peeling-off thereof. 
     When blue light is incident on a boundary portion between a green pixel and a red pixel in the conventional solid-state imaging device of Patent Document 1, the blue light is absorbed by the green color filter layer  20 G present in the boundary portion with only a small amount of the blue light passing through the green color filter layer  20 G to be diffusely reflected by the surface of the light blocking film  17 , etc. As a result, the amount of light to be received by a photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the red color filter layers  20 R does not substantially change. Although not shown in the figure, also when blue light is incident on a boundary portion between a green pixel and a blue pixel, the blue light is absorbed by the green color filter layer  20 G present in the boundary portion with only a small amount of the blue light passing through the green color filter layer  20 G to be diffusely reflected by the surface of the light blocking film  17 , etc. As a result, the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the blue color filter layers  20 B does not substantially change. Thus, even if blue light is incident on a pixel boundary portion, the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the red color filter layers  20 R will not be different from the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the blue color filter layers  20 B. 
     This similarly holds true when the incident light is red light. When red light is incident on a boundary portion between a green pixel and a red pixel, the red light is absorbed by the green color filter layer  20 G present in the boundary portion with only a small amount of the red light passing through the green color filter layer  20 G to be diffusely reflected. As a result, the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the red color filter layers  20 R does not substantially change. Also when red light is incident on a boundary portion between a green pixel and a blue pixel, the red light is absorbed by the green color filter layer  20 G present in the boundary portion with only a small amount of the red light passing through the green color filter layer  20 G to be diffusely reflected. As a result, the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the blue color filter layers  20 B does not substantially change. Thus, even if red light is incident on a pixel boundary portion, the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the red color filter layers  20 R will not be different from the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the blue color filter layers  20 B. 
     Thus, the color filter  20  is formed so that the green color filter layer  20 G is larger than the pixel size and so that the edge of the green color filter layer  20 G overlaps the edge of the red color filter layer  20 R or the blue color filter layer  20 B. Then, the sensitivity of the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the red color filter layers  20 R or the blue color filter layers  20 B will not be different from that of others, thereby preventing line noise from occurring due to the arrangement of pixels forming rows and columns of the color filter  20 . 
       FIGS. 4A and 4B  are spectral characteristics showing the absorption of red light and blue light by the green color filter layers  20 G. As shown in  FIGS. 4A and 4B , red light and blue light are absorbed by green filter layers. 
     Therefore, in the color filter of Patent Document 1, the edge of the green color filter layers  20 G overlaps the edge of the red color filter layers  20 R or the blue color filter layers  20 B, thereby improving the adhesion between the color filter layers and preventing line noise from occurring due to sensitivity non-uniformity. 
       FIG. 18  is a plan view of a color filter of another conventional solid-state imaging device as disclosed in Japanese Laid-Open Patent Publication No. 2001-21715 (hereinafter “Patent Document 2”).  FIGS. 19A to 20B  are schematic cross-sectional views showing the structure of  FIG. 18 , wherein  FIGS. 19A and 20A  are cross-sectional views taken along line XIXa-XIXa in  FIG. 18 , and  FIGS. 19B and 20B  are cross-sectional views taken along line XIXb-XIXb in  FIG. 18 . 
     As shown in  FIG. 18 , a color filter of Patent Document 2 includes the green color filter layers  20 G arranged in a checker pattern, as are those in the conventional solid-state imaging device of Patent Document 1, with the green color filter layers  20 G being coupled together in diagonal directions by means of bridge portions. Then, the gap between pixels is filled up to improve the adhesion, and it is possible to eliminate the difference between the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed between the red color filter layers  20 R and the amount of light to be received by the photoelectric transducer  13 G located under the green color filter layer  20 G interposed by the blue color filter layers  20 B. 
     Thus, the color filter of Patent Document 2 employs a structure where the green color filter layers  20 G are coupled together in diagonal directions by means of bridge portions, whereby it is possible to improve the adhesion of the color filter and to prevent line noise from occurring due to sensitivity non-uniformity. 
     SUMMARY OF THE INVENTION 
     However, the conventional solid-state imaging devices of Patent Documents 1 and 2, which are provided with a color filter in which the green filter layer  20 G is larger than the pixel size, have the following problems. 
     First, as shown in  FIGS. 17A ,  17 B,  20 A and  20 B, where an oblique light beam “a” is incident on a pixel boundary portion, since the green filter layers  20 G are larger, the oblique light beam “a” may pass through the green filter layer  20 G and be incident on the red filter layer  20 R or the blue color filter layer  20 B. This causes mixture of colors, thereby failing to obtain a high-definition image. 
     Moreover, as shown in  FIGS. 17A ,  17 B,  20 A and  20 B, where an oblique light beam “b” is incident on a pixel boundary portion, the oblique light beam “b” may pass through the green color filter layer  20 G and then be incident on a photoelectric transducer  13 R of a red pixel located under the adjacent red filter layer  20 R. As a result, a portion of a short-wavelength component of the green wavelength range is added to the red spectral characteristics, thereby increasing the sensitivity for red. Similarly, where the oblique light beam “b” passes through the green color filter layer  20 G and is then incident on a photoelectric transducer  13 B of a blue pixel located under the adjacent blue filter layer  20 B, a portion of a long-wavelength component of the green wavelength range is added to the blue spectral characteristics, thereby increasing the sensitivity for blue. Then, the overall sensitivity will be inaccurate. 
     Moreover, where the green color filter layer  20 G is designed (resized) to be larger than the pixel size to suppress line noise, as in the color filter of Patent Document 1, it is difficult to optimize the amount of resizing for the particular solid-state imaging device. Specifically, it is very difficult to determine an amount of resizing with which oblique light beams have little influence and which is effective in suppressing line noise. 
     In order to realize desirable spectral characteristics, it is necessary to apply a color resist to be a color filter layer with a sufficient thickness. However, as the color resist becomes thicker, it is more likely that ultraviolet radiation (i line), for example, used in the exposure step in a photolithography process is absorbed by the color resist being irradiated with the i line, whereby the i line will not reach a deep portion. With the exposure of a deep portion being insufficient, the photopolymerization will be insufficient, whereby exfoliation occurs more easily. Moreover, it is very difficult to granulate pigment particles, and even if granulation is achieved, an increase in the secondary particle size due to the dispersion process is inevitable. Therefore, it is difficult to realize a thin pigment-dispersed color resist. The exposure time has been extended in order to prevent exfoliation due to insufficient photopolymerization. However, an increase in the exposure time also increases the amount of time over which the incident light repeats diffuse reflection by pigment particles, thereby deteriorating the edge shape. Then, high-definition images may not be obtained by the solid-state imaging device. 
     Moreover, in the conventional solid-state imaging device, since the color filter layer has a large thickness as described above, the edge thereof as seen in a cross-sectional view is not vertical to the substrate but is slanted at an angle. In other words, the green color filter layers  20 G to be formed in the first layer each have a trapezoidal cross section (upper side length&lt;lower side length). In the solid-state imaging device of Patent Document 1, the color filter layers in the second layer (e.g., the red color filter layers  20 R) and those in the third layer (e.g., the blue color filter layers  20 B) are formed so as to cover the edge of the pattern of the green color filter layer  20 G formed in the first layer, whereby the edge portion of the red color filter layer  20 R and the blue color filter layer  20 B stands higher from the photoelectric transducer  13  than the central portion thereof. As a result, as shown in  FIG. 17A , an oblique light beam is more likely to pass through the edge portion of the color filter layer of an adjacent pixel, thereby failing to realize desirable spectral characteristics and resulting in mixture of colors. 
     Particularly, in a structure where edges of color filter layers overlap each other, the color filter has an increased thickness and the distance from the photoelectric transducer  13  to the microlens  22  is longer in a boundary portion between adjacent pixels. This adversely influences the optical characteristics of the solid-state imaging device. 
     Another problem is that the alignment margin in the cross section of the color filter  20  decreases as the pixel size is reduced. If there is a misalignment, incident light passes through the peripheral portion of the color filter layer of an adjacent pixel, thus resulting in more significant mixture of colors, thereby failing to realize desirable spectral characteristics. 
     When green color filter layers are formed in a checker pattern in a color filter of the Bayer arrangement, the poor resolution of the color resist material may deteriorate the edge shape of the color filter layers in the peripheral region, and in some cases, the outline of the color filter layers may be deformed. Such an outline deformation has no regularity, and it is therefore difficult to address the problem with mask designs. 
     In the solid-state imaging device of Patent Document 2, in the formation of green filter layers being a colored pattern formed in the first layer, the checker pattern of unit pixels are coupled together by means of connecting portions. In practice, however, due to the poor resolution of the photosensitive colored resist, it is difficult to keep the shape of the connecting portions if the pixel size is reduced. As a result, the thickness and shape of the connecting portions will be non-uniform, and in worst cases, the connecting portions may not be formed at all or the shape of the unit pixel may be deformed. Moreover, the red and blue filter layers are formed afterwards in regions surrounded by the green filter layers. Therefore, if there is a misalignment, adjacent color filter layers may have a gap therebetween or the red and blue color filter layers may overlap the green filter layers. As a result, the obtained color filter will not be flat, whereby it is difficult to reduce the thickness of the flattening film under the microlens array, and the shape of the microlenses formed afterwards may be non-uniform. A solid-state imaging device manufactured with these problems will have poor optical characteristics due to sensitivity non-uniformity. Moreover, if a reduction in the thickness of a solid-state imaging device is not realized, it is expected that optical characteristics thereof, e.g., the sensitivity, the smear, the shading, etc., will be deteriorated. 
     In view of these problems in the prior art, the present invention has an object to address the reduction in the pixel sizes by realizing a large alignment margin and realizing the formation of a gap-less, stable color filter, whereby it is possible to prevent problems such as sensitivity non-uniformity and mixture of colors, and to realize desirable optical characteristics in terms of the sensitivity, the smear, the shading, etc. 
     In order to achieve the object set forth above, the present invention provides a solid-state imaging device in which one of color filter layers, which accounts for the largest portion of the sensing area, is formed in two separate steps. 
     Specifically, a solid-state imaging device of the present invention includes: photoelectric transducers arranged in a matrix pattern on a substrate; and a plurality of color filter layers of different colors formed above the photoelectric transducers so as to correspond to the photoelectric transducers, wherein one of the color filter layers of the color, which accounts for a largest area, is formed by two layers which are a bottom layer and a top layer of the color filter layers. 
     With the solid-state imaging device of the present invention, the edge portion of each pixel is formed precisely, thus improving the dimension non-uniformity. This reduces variations from line to line of the sensitivity for incident light, thus improving the mixture of colors, the line noise, the sensitivity non-uniformity, etc. In the exposure step of forming the bottom layer and the top layer, light is more likely to reach the inside, whereby it is possible to prevent the exfoliation due to insufficient photopolymerization. 
     In the solid-state imaging device of the present invention, it is preferred that the bottom layer is wider than the top layer. 
     This increases the contact area and the adhesion between the underlying layer and the bottom layer of the one of the color filter layers, which accounts for the largest portion of the sensing area. Moreover, since the top layer is formed on the bottom layer, the adhesion is reinforced. 
     In the solid-state imaging device of the present invention, it is preferred that the bottom layer is wider than the top layer, and the top layer is wider than any of the other color filter layers. 
     Then, the bottom layer and the top layer of the one of the color filter layers are each formed to be larger than the pixel size with a larger width than those of the other color filter layers, whereby it is possible to eliminate the gap between adjacent pixels. 
     In the solid-state imaging device of the present invention, it is preferred that: the one of the color filter layers has a thickness such that a sum of a thickness of the bottom layer and that of the top layer yields desirable spectral characteristics; and the thickness of the bottom layer is less than or equal to ½ the thickness of the one of the color filter layers. 
     Then, the shape of the edge portion of the bottom layer can be improved to be closer to being vertical to the substrate, and the dimension precision can be improved. Therefore, it is possible to form a bottom layer with a little deformation. Moreover, in the exposure step of forming the bottom layer, the bottom layer can be sufficiently photopolymerized. 
     In the solid-state imaging device of the present invention, it is preferred that the one of the color filter layers has a thickness such that a sum of a thickness of the bottom layer and that of the top layer yields desirable spectral characteristics; and the thickness of the top layer is greater than or equal to ½ the thickness of the one of the color filter layers. 
     Then, the thickness of the bottom layer can be made less than or equal to ½ the desired thickness of the one of the color filter layers, whereby it is possible to form the bottom layer with a little deformation. Moreover, in the exposure step of forming the one of the color filter layers, the bottom layer and the top layer can be sufficiently photopolymerized. 
     In the solid-state imaging device of the present invention, it is preferred that edge portions of the other color filter layers are interposed between the bottom layer and the top layer. 
     Then, it is possible to reduce the height and angle of the rise of the edge portions of the other color filter layers formed on the bottom layer. Thus, it is possible to improve the shape of the edge portions of the other color filter layers. The edge portions of the other color filter layers formed on the bottom layer are interposed between the bottom layer and the top layer, and the top layer is therefore formed so as to fill portions where the other color filter layers are absent. Thus, the edge portion of each pixel is formed precisely, and there will be no gap between adjacent pixels, thereby improving the dimension non-uniformity. Therefore, it is possible to prevent line noise occurring due to light being incident on a pixel boundary portion. The mixture of colors from adjacent color filter layers can be prevented even if a light beam oblique with respect to the substrate is incident on a pixel boundary portion, whereby it is possible to improve the mixture of colors, the line noise and the sensitivity non-uniformity. 
     In the solid-state imaging device of the present invention, it is preferred that the one of the color filter layers is a green color filter layer. 
     In the solid-state imaging device of the present invention, it is preferred that the one of the color filter layers is a green color filter layer, and the other color filter layers are red and blue color filter layers. 
     A method of the present invention is a method for manufacturing a solid-state imaging device, the solid-state imaging device including photoelectric transducers arranged in a matrix pattern on a substrate, and a plurality of color filter layers of different colors formed above the photoelectric transducers so as to correspond to the photoelectric transducers, the method including the steps of: forming a first layer of one of the color filter layers, which accounts for a largest area, so that the first layer has a thickness less than or equal to ½ a thickness that yields desirable spectral characteristics; forming other color filter layers so that edge portions of the other color filter layers are provided on the first layer; and forming, on the first layer, a second layer of the one of the color filter layers having a width smaller than that of the first layer and a thickness greater than or equal to that of the first layer, so that the edge portions of the other color filter layers are interposed between the first layer and the second layer. 
     With the method for manufacturing a solid-state imaging device of the present invention, one of the color filter layers, which accounts for the largest portion of the sensing area, can be formed by two layers being the bottom layer and the top layer, forming a plurality of color filter layers. Moreover, it is possible to manufacture a solid-state imaging device in which the edge portions of the other color filter layers are interposed by the two layers of the one of the color filter layers, and the bottom layer and the top layer each having a larger width than those of the other color filter layers, with the bottom layer having a thickness less than or equal to that of the top layer. 
     In the method for manufacturing a solid-state imaging device of the present invention, it is preferred that the first layer and the second layer are formed by using the same photomask. 
     Then, it is possible to suppress an increase in the manufacturing cost. 
     In the method for manufacturing a solid-state imaging device of the present invention, it is preferred that one of the color filter layers is a green color filter layer. 
     In the method for manufacturing a solid-state imaging device of the present invention, it is preferred that one of the color filter layers is a green color filter layer, and the other color filter layers are red and blue color filter layers. 
     As described above, with the solid-state imaging device of the present invention and the method for manufacturing the same, it is possible to precisely form a color filter while preventing the exfoliation of color filter layers and the formation of a gap therebetween. Thus, it is possible to obtain a solid-state imaging device having desirable optical characteristics. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view showing a color filter of a solid-state imaging device according to an example embodiment. 
         FIGS. 2A and 2B  are cross-sectional views showing the solid-state imaging device according to the example embodiment, wherein  FIG. 2A  is a cross-sectional view taken along line IIa-IIa in  FIG. 1 , and  FIG. 2B  is a cross-sectional view taken along line IIb-IIb in  FIG. 1 . 
         FIGS. 3A and 3B  are cross-sectional views showing the solid-state imaging device according to the example embodiment where light is incident on a pixel boundary portion, wherein  FIG. 3A  is a cross-sectional view taken along line IIa-IIa in  FIG. 1 , and  FIG. 3B  is a cross-sectional view taken along line IIb-IIb in  FIG. 1 . 
         FIG. 4A  shows spectral characteristics, showing the absorption of blue light by green filter layers, and  FIG. 4B  shows spectral characteristics, showing the absorption of red light by green filter layers. 
         FIGS. 5A and 5B  are cross-sectional views showing the solid-state imaging device according to the example embodiment where an oblique light beam is incident on a pixel boundary portion, wherein  FIG. 5A  is a cross-sectional view taken along line IIa-IIa in  FIG. 1 , and  FIG. 5B  is a cross-sectional view taken along line IIb-IIb in  FIG. 1 . 
         FIG. 6  is a plan view showing a manufacturing process of the solid-state imaging device according to the example embodiment, at a point where the passivation film has been formed. 
         FIGS. 7A and 7B  show the manufacturing process of the solid-state imaging device according to the example embodiment, wherein  FIG. 7A  is a cross-sectional view taken along line VIIa-VIIa in  FIG. 6 , and  FIG. 7B  is a cross-sectional view taken along line VIIb-VIIb in  FIG. 6 . 
         FIG. 8  is a plan view showing the manufacturing process of the solid-state imaging device according to the example embodiment, at a point where first green filter layers have been formed. 
         FIGS. 9A and 9B  show the manufacturing process of the solid-state imaging device according to the example embodiment, wherein  FIG. 9A  is a cross-sectional view taken along line IXa-IXa in  FIG. 8 , and  FIG. 9B  is a cross-sectional view taken along line IXb-IXb in  FIG. 8 . 
         FIG. 10  is a plan view showing the manufacturing process of the solid-state imaging device according to the example embodiment, at a point where red filter layers and blue filter layers have been formed. 
         FIGS. 11A and 11B  show the manufacturing process of the solid-state imaging device according to the example embodiment, wherein  FIG. 11A  is a cross-sectional view taken along line XIa-XIa in  FIG. 10 , and  FIG. 11B  is a cross-sectional view taken along line XIb-XIb in  FIG. 10 . 
         FIG. 12  is a plan view showing the manufacturing process of the solid-state imaging device according to the example embodiment, at a point where second green filter layers have been formed. 
         FIGS. 13A and 13B  show the manufacturing process of the solid-state imaging device according to the example embodiment, wherein  FIG. 13A  is a cross-sectional view taken along line XIIIa-XIIIa in  FIG. 12 , and  FIG. 13B  is a cross-sectional view taken along line XIIIb-XIIIb in  FIG. 12 . 
         FIG. 14  is a diagram illustrating how to determine the size of a first green filter layer of the solid-state imaging device according to the example embodiment. 
         FIG. 15  is a plan view showing an example of a color filter of three primary colors of a conventional solid-state imaging device. 
         FIGS. 16A and 16B  are cross-sectional view showing the conventional solid-state imaging device, wherein  FIG. 16A  is a cross-sectional view taken along line XVIa-XVIa in  FIG. 15 , and  FIG. 16B  is a cross-sectional view taken along line XVIb-XVIb in  FIG. 15 . 
         FIGS. 17A and 17B  are cross-sectional views showing an oblique light beam being incident on a pixel boundary portion in a cross section of the conventional solid-state imaging device shown in  FIG. 15 . 
         FIG. 18  is a plan view showing another example of a color filter of three primary colors of a conventional solid-state imaging device. 
         FIGS. 19A and 19B  are cross-sectional views showing the conventional solid-state imaging device, wherein  FIG. 19A  is a cross-sectional view taken along line XIXa-XIXa in  FIG. 18 , and  FIG. 19B  is a cross-sectional view taken along line XIXb-XIXb in  FIG. 18 , showing light being incident on a pixel boundary portion. 
         FIGS. 20A and 20B  are cross-sectional views showing the conventional solid-state imaging device shown in  FIG. 18  where an oblique light beam is incident on a pixel boundary portion. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An example solid-state imaging device will now be described with reference to the drawings. 
       FIG. 1  is a plan view showing a color filter of a solid-state imaging device according to an example embodiment, as viewed from the lens side. 
     As shown in  FIG. 1 , the solid-state imaging device of the present embodiment includes a color filter including green color filter layers arranged in a checker pattern, and includes blue color filter layers and red color filter layers alternating with each other by rows or by columns to fill the open spots in the checker pattern, as in the conventional solid-state imaging device. 
       FIG. 2A  shows a cross section taken along line IIa-IIa in  FIG. 1 , i.e., along a row of the color filter layer arrangement, and  FIG. 2B  shows a cross section taken along line IIb-IIb in  FIG. 1 , i.e., along a diagonal line of the color filter. What is shown in each of these figures accounts for four photoelectric transducers. 
     As shown in  FIGS. 2A and 2B , a solid-state imaging device  10  of the present embodiment includes a semiconductor substrate  11  of a first conductivity type (e.g., N-type), and a semiconductor well (P well) layer  12  of a second conductivity type (e.g., P-type) opposite to the conductivity type of the semiconductor substrate  11 , with a plurality of photoelectric transducers  13  formed in an upper portion of the P well layer  12 . The photoelectric transducers  13  are formed by semiconductor regions of the first conductivity type, and are arranged in a matrix pattern as viewed from above. 
     A gate insulating film  14  is formed on the P well layer  12  and the photoelectric transducers  13 . Transfer electrodes  15  of polycrystalline silicon are formed on the gate insulating film  14  between the photoelectric transducers  13  as viewed from above. An interlayer insulating film  16  for an insulative coating is formed on the upper surface and the side surface of the transfer electrode  15 , and a light blocking film  17  of tungsten (W), or the like, is formed on the upper surface and the side surface of the interlayer insulating film  16  and on the upper surface of the semiconductor substrate  11  excluding the openings of the photoelectric transducers  13 . A passivation film  18  of a silicon oxynitride film (SiON), or the like, is formed on the upper surface of the gate insulating film  14  and the light blocking film  17 . Since the passivation film  18  is formed so as to cover the transfer electrodes  15 , the interlayer insulating film  16  and the light blocking film  17  formed on the gate insulating film  14 , the passivation film  18  is formed with depressed portions in portions where the passivation film  18  is in contact with the gate insulating film  14 , i.e., in portions above the openings of the photoelectric transducers  13 . A first transparent flattening layer  19   a  of a photosensitive transparent film whose main component is a phenol resin, or the like, is formed in the depressed portions, with the upper surface of the first transparent flattening layer  19   a  being flush with the upper surface of the passivation film  18 . 
     A second transparent flattening layer  19   b  of an acrylic thermosetting transparent resin is formed on the flush surface formed by the passivation film  18  and the first transparent flattening layer  19   a , and a color filter  20  including green filter layers  20 G, red filter layers  20 R and blue filter layers  20 B is formed on the second transparent flattening layer  19   b . Each color filter layer corresponds to one of the underlying photoelectric transducers  13 . 
     Each green filter layer  20 G includes a first green filter layer  21   a  being on the bottom layer of the color filter  20 , and a second green filter layer  21   b  formed on the first green filter layer  21   a  and being the top layer of the color filter  20 . The first green filter layer  21   a  and the second green filter layer  21   b  have thicknesses such that the first green filter layer  21   a  and the second green filter layer  21   b  together realize desirable spectral characteristics. Each green filter layer  20 G is formed to be wider than the opening of the photoelectric transducer  13  so that the green filter layers  20 G together from a checker pattern corresponding to the photoelectric transducers  13  as shown in  FIG. 1 . The first green filter layer  21   a  has a thickness less than or equal to that of the second green filter layer  21   b  and has an area greater than that of the second green filter layer  21   b . The first green filter layers  21   a  and the second green filter layers  21   b  are provided so that edge portions of the red filter layers  20 R and the blue filter layers  20 B are interposed therebetween, thus forming a sandwich structure. 
     A third transparent flattening layer  19   c  of a thermosetting transparent resin whose main component is an acrylic resin is formed on the color filter  20 , and an array of microlenses  22  is formed on the third transparent flattening layer  19   c  so that the microlenses  22  correspond to the pixels. 
     In the solid-state imaging device of the present embodiment, the color filter  20  is formed as follows. That is, the green filter layers  20 G, which account for the largest portion of the sensing area among the red, green and blue color filter layers corresponding to the photoelectric transducers  13 , are formed to be largest, wherein each green color filter layer  20 G includes the first green filter layer  21   a  and the second green filter layer  21   b , with the first green filter layer  21   a  being wider than, and having a thickness less than or equal to that of, the second green filter layer  21   b . Therefore, in terms of the area with respect to the photoelectric transducer  13 , the green filter layers  20 G, which account for the largest portion of the sensing area, are larger than the red filter layers  20 R or the blue filter layers  20 B, thereby improving the adhesion with the second transparent flattening layer  19   b . Moreover, with the green filter layer  20 G being divided into two layers each having a smaller thickness, it is possible to increase process margins such as the focus margin, the exposure margin, and the alignment margin. Particularly, a green color resist has a low transmittance for ultraviolet radiation (e.g., the i line) used in the exposure step, and the photopolymerization is likely to be insufficient in deep portions, thus resulting in exfoliation. In the present embodiment, however, the two layers of a color resist are each exposed separately, whereby incident light is more likely to reach deep portions of the color resist. Thus, the photopolymerization will be sufficient, thus preventing exfoliation. Moreover, since over-exposure is not needed, the resolution in the edge portion will not be deteriorated, whereby it is possible to obtain a high-definition image with the solid-state imaging device. 
     The green filter layer  20 G is formed by layering the second green filter layer  21   b  having a smaller area than the first green filter layer  21   a  on the first green filter layer  21   a , with the edge portion of the red filter layer  20 R and that of the blue filter layer  20 B being interposed therebetween, thus forming a sandwich structure. Therefore, the edge portion of the red filter layer  20 R and that of the blue filter layer  20 B are formed on the first green filter layer  21   a , whereby it is possible to prevent halation from the light blocking film  17 , etc., and to improve the resolution in the edge portion. With the second green filter layer  21   b  being layered on the first green filter layer  21   a , the adhesion therebetween is desirable, and the adhesion in the edge portion is also improved in a sandwich structure where the edge portion of the red filter layer  20 R and that of the blue filter layer  20 B are interposed therebetween, thus ensuring a sufficient margin for exfoliation. 
     Thus, the gap between adjacent the color filter layers along the edge portion of each pixel, particularly at the corner portions thereof, is substantially eliminated, whereby it is possible to maintain, at a certain level, the amount of scattered light of the incident light on the light blocking film  17 , thus eliminating the sensitivity non-uniformity between pixels. 
       FIGS. 3A and 3B  are cross-sectional views showing the solid-state imaging device of the present embodiment where light is incident on a pixel boundary portion, wherein  FIG. 3A  is a cross-sectional view taken along line IIa-IIa in  FIG. 1 , and  FIG. 3B  is a cross-sectional view taken along line IIb-IIb in  FIG. 1 . 
     Consider a case where a blue or red light beam substantially vertical to the semiconductor substrate  11  is incident on a pixel boundary portion, as shown in  FIGS. 3A and 3B . 
     Since the green filter layer  20 G is larger than the red filter layer  20 R and the blue filter layer  20 B, the green filter layer  20 G is present in the region where a blue light beam incident on a pixel boundary portion passes through. Since the first green filter layer  21   a  and the second green filter layer  21   b  absorb most of the blue spectrum, there is only a small amount of blue light to be scattered at the surface of the light blocking film  17 , etc. Therefore, there is substantially no increase in the amount of light to be received by the photoelectric transducer  13 G corresponding to the green filter layer  20 G surrounded by the blue filter layers  20 B or the amount of light to be received by the photoelectric transducer  13 G corresponding to the green filter layer  20 G surrounded by the red filter layers  20 R. Similarly, where red light is incident on a pixel boundary portion, since the green filter layer  20 G absorbs most of the red spectrum, there is only a small amount of red light to be scattered at the surface of the light blocking film  17 , etc. Therefore, there is substantially no increase in the amount of light to be received by the photoelectric transducer  13 G corresponding to the green filter layer  20 G surrounded by the blue filter layers  20 B or the amount of light to be received by the photoelectric transducer  13 G corresponding to the green filter layer  20 G surrounded by the red filter layers  20 R. 
     Therefore, no matter whether blue light or red light is incident, the amount of light to be received by the photoelectric transducer  13 G corresponding to the green filter layer  20 G surrounded by the blue filter layers  20 B is not substantially different from the amount of light to be received by the photoelectric transducer  13 G corresponding to the green filter layer  20 G surrounded by the red filter layers  20 R. Therefore, there is no line noise due to blue light and no line noise due to red light. 
       FIG. 4A  shows spectral characteristics, showing the absorption of blue light by green filter layers, and  FIG. 4B  shows spectral characteristics, showing the absorption of red light by green filter layers. In  FIGS. 4A and 4B , a dotted line represents the spectral characteristics of blue light or red light, a one-dot-chain line represents the spectral characteristics of the green filter layer, and a solid line represents the spectral characteristics of the absorption of blue light or red light by the green filter layer. 
     It can be seen from  FIGS. 4A and 4B  that blue light and red light are mostly absorbed by the green filter layer. It can also be seen that blue light or red light is transmitted intact through the filter if it does not pass through the green filter layer. Therefore, if the green filter layer  20 G is larger than the red filter layer  20 R and the blue filter layer  20 B so that light entering between adjacent pixels passes through a portion of the green filter layer  20 G, it is possible to substantially eliminate the influence of light entering between adjacent pixels and to prevent line noise. 
       FIGS. 5A and 5B  are cross-sectional views showing the solid-state imaging device of the present embodiment, where a light beam oblique with respect to the semiconductor substrate is incident on a pixel boundary portion, wherein  FIG. 5A  is a cross-sectional view taken along line IIa-IIa in  FIG. 1 , and  FIG. 5B  is a cross-sectional view taken along line IIb-IIb in  FIG. 1 . 
     As shown in  FIGS. 5A and 5B , even if a light beam at an inclined angle with respect to the semiconductor substrate is incident on a pixel boundary portion of the solid-state imaging device of the present embodiment, the incident light beam passes only through the green filter layer  20 G or passes through either the red filter layer  20 R or the blue filter layer  20 B, and it does not pass through both the green filter layer  20 G and the red filter layer  20 R or the blue filter layer  20 B. Specifically, for each pixel, the green filter layer  20 G is formed to be larger than the red filter layer  20 R or the blue filter layer  20 B, and the green filter layer  20 G includes two layers including the first green filter layer  21   a  being the lower layer and the second green filter layer  21   b  being the upper layer, with the first green filter layer  21   a  being wider than, and having a thickness less than or equal to that of, the second green filter layer  21   b , whereby even if an oblique light beam is incident on a pixel boundary portion, it is unlikely to be influenced by adjacent color filter layers. Therefore, it is possible to prevent mixture of colors in the blue filter layer  20 B or the red filter layer  20 R surrounded by the green filter layers  20 G, thereby obtaining a high-definition image. Moreover, the sensitivity of the blue filter layer  20 B or the red filter layer  20 R surrounded by the green filter layers  20 G will not be increased by mixture of colors from the adjacent green filter layers  20 G. 
     Thus, in the solid-state imaging device of the present embodiment, the thickness of the first green filter layer  21   a  is less than or equal to ½ the desirable thickness, whereby it is possible to reduce the height and angle of the rise, from the semiconductor substrate  11 , of the edge portion of the red filter layer  20 R and the blue filter layer  20 B formed on the first green filter layer  21   a . Moreover, since the edge portion of the red filter layer  20 R and the blue filter layer  20 B is formed on the first green filter layer  21   a , it is possible to reduce halation from the light blocking film  17 . Moreover, since the red filter layer  20 R and the blue filter layer  20 B are formed with thinner edge portions, it is possible to precisely form the edge portions of the color filter layers. 
     Next, a method for manufacturing the solid-state imaging device  10  of the present embodiment will be described with reference to  FIGS. 6 to 13B .  FIGS. 6 ,  8 ,  10  and  12  are plan views, and  FIGS. 7A ,  7 B,  9 A,  9 B,  11 A,  11 B,  13 A and  13 B are cross-sectional views. 
       FIG. 6  is a plan view showing a manufacturing step where the passivation film  18  has been formed on the semiconductor substrate  11 , as viewed from the side on which lenses are formed,  FIG. 7A  is a cross-sectional view taken along VIIa-VIIa in  FIG. 6 , and  FIG. 7B  is a cross-sectional view taken along line VIIb-VIIb in  FIG. 6 . 
     As shown in  FIGS. 6 ,  7 A and  7 B, the solid-state imaging device  10  of the present embodiment includes the semiconductor substrate  11  of the first conductivity type, e.g., the N-type, and the P well layer  12  of the second conductivity type being the opposite conductivity to the first conductivity type formed on the semiconductor substrate  11 , with a plurality of photoelectric transducers  13  being formed in an upper portion of the P well layer  12  from an N-type diffusion layer. As viewed from above, the photoelectric transducers  13  are arranged in a matrix pattern, and are formed by repeating the photolithography step, the ion implantation step and the thermal diffusion step. 
     Then, the gate insulating film  14  is formed on the P well layer  12  and the photoelectric transducers  13 , and the transfer electrodes  15  of polycrystalline silicon are formed on the gate insulating film  14 . The transfer electrodes  15  are each formed in a region between the photoelectric transducers  13  as viewed from above, and the surfaces thereof, i.e., the side surface and the upper surface thereof, are covered by the interlayer insulating film  16  for electrical insulation, with the light blocking film  17  of tungsten, or the like, being further formed so as to cover the interlayer insulating film  16 . 
     Then, the passivation film  18  such as a boron-phosphorus silicon glass (BPSG film) or an SiON film is formed on the gate insulating film  14  and the light blocking film  17  by heat flow, for example. Although not shown in the figures, wiring of an aluminum alloy, or the like, is provided, and an SiON film, or the like, for example, is deposited in order to protect the wiring, and a bonding pad for electrode extraction is formed. At this point, there is a depressed portion in each region that is above the photoelectric transducer  13  and where the transfer electrode  15  is absent. 
       FIG. 8  is a plan view showing a manufacturing process at a point where the depressed portions in the passivation film  18  have been filled up with the first green filter layers  21   a  having been formed thereon, and  FIGS. 9A and 9B  are cross-sectional views taken along lines IXa-IXa and IXb-IXb, respectively, in  FIG. 8 . 
     As shown in  FIGS. 8 ,  9 A and  9 B, the depressed portions between protruding portions formed by the provision of the transfer electrodes  15  and wiring on the N-type semiconductor substrate  11  are filled up with the first transparent flattening layer  19   a  as a pre-treatment for improving the precision of color filter layers to be formed in a subsequent step. The first transparent flattening layer  19   a  is formed by applying a photosensitive transparent resist whose main component is a phenol resin, for example, and performing an exposure and development process (including bleaching and baking) using a predetermined photomask. The transmittance is increased by ultraviolet irradiation. Instead of applying a photosensitive transparent resist and then exposing and developing the photosensitive transparent resist to fill up the depressed portions, the first transparent flattening layer  19   a  may be formed by, for example, applying a transparent resist in a plurality of iterations and then flattening the surface thereof by a known etch-back process, by applying a transparent film and then flattening the transparent film by a heat flow process, or by using a combination of these methods to further improve the flatness. 
     Then, the second transparent flattening layer  19   b  is formed on the passivation film  18  and the first transparent flattening layer  19   a  as a pre-treatment for improving the adhesion with the color filter and reducing the development residue. The second transparent flattening layer  19   b  is formed by, for example, applying an acrylic thermosetting transparent resin or a hexamethyldisilazane (HMDS) film on the passivation film  18  and the first transparent flattening layer  19   a , and then performing a heat treatment to cure the applied film. 
     Then, the first green color filter layers  21   a  are formed in a checker pattern corresponding to the photoelectric transducers  13 , as viewed from above, on the second transparent flattening layer  19   b . The first green color filter layer  21   a  is formed by applying, on the second transparent flattening layer  19   b , a photosensitive negative-type green color resist containing a dye or a pigment that is prepared so that light of the green wavelength range is selectively transmitted, and then performing an exposure step and a development step using a predetermined photomask. The first green filter layer  21   a  is formed using a photomask such that the first green filter layer  21   a  can be formed to be wider than the corresponding pixel so that there is no gap between color filter layers at the pixel boundary portion. The photosensitive negative-type green color resist is applied so that the thickness of the first green filter layer  21   a  is less than or equal to ½ the desirable thickness. The thickness is set taking into consideration various factors, such as, for example, suppressing the height and angle of the rise of the edge portion of the red filter layer  20 R and the blue filter layer  20 B to be formed later, reducing halation from the light blocking film  17 , precisely defining the outline, and the possibility that the mask may be misaligned. Specifically, although a smaller thickness is preferred for suppressing the height and angle of the rise of the edge portion and the mask misalignment, a larger thickness is preferred for suppressing halation and precisely defining the outline. Taking into consideration a further reduction in the thickness, a green color resist for forming the first green filter layer  21   a  may be applied following the vapor deposition of an HMDS film, for example, instead of using the second transparent flattening layer  19   b.    
     The width of the first green filter layer  21   a  will now be described. 
       FIG. 14  is a cross-sectional view showing the width of the first green filter layer  21   a.    
     Referring to  FIG. 14 , where “a” denotes the width of a unit pixel in the cross section taken in the column direction of unit pixels of the solid-state imaging device and “b” denotes the width of each opening in the passivation film  18  above a photoelectric transducer, the width of the first green filter layer  21   a  is set to be greater than “a” and less than or equal to “2a−b”. If the with of the first green filter layer  21   a  is set to be large, although the amount of overlap between color filter layers will be increased, the mask alignment margin will be small. If the width of the first green filter layer  21   a  is set to be small, a gap may be formed between color filter layers. 
       FIG. 10  is a plan view showing a manufacturing process at a point where the red filter layers  20 R and the blue filter layers  20 B have been formed, and  FIGS. 11A and 11B  are cross-sectional views taken along lines XIa-XIa and XIb-XIb, respectively, in  FIG. 10 . 
     As shown in  FIGS. 10 ,  11 A and  11 B, after the formation of the first green filter layers  21   a , the red filter layers  20 R of the color filter  20  are formed. The red filter layers  20 R are formed in every other rows and in every other columns so as to fill pixel positions where the first green filter layers  21   a  are absent. The red filter layers  20 R are formed by applying a resist containing a dye or a pigment that is prepared so that light of the red wavelength range is selectively transmitted, and then performing an exposure step and a development step using a predetermined photomask, in a manner similar to that of the first green filter layers  21   a . The red filter layer  20 R is formed to be narrower than the first green filter layer  21   a  with the edge portion thereof being laid on the first green filter layer  21   a.    
     Then, after the formation of the red filter layers  20 R, the blue filter layers  20 B are formed. The blue filter layers  20 B are formed so as to fill pixel positions where the first green filter layers  21   a  and the red filter layers  20 R are absent. The blue filter layers  20 B are formed by applying a resist containing a dye or a pigment that is prepared so that light of the blue wavelength range is selectively transmitted, and then performing an exposure step and a development step using a predetermined photomask, in a manner similar to that of the red filter layers  20 R. The blue filter layer  20 B is formed to be narrower than the first green filter layer  21   a  with the edge portion thereof being laid on the first green filter layer  21   a.    
     Although the blue filter layers  20 B are formed after the formation of the red filter layers  20 R in the illustrated example, the order of formation may be reversed as long as the red filter layers  20 R and the blue filter layers  20 B are formed after the formation of the first green filter layers  21   a.    
       FIG. 12  is a plan view showing a manufacturing process at a point where the second green filter layers  21   b  have been formed on the first green filter layers  21   a , and  FIGS. 13A and 13B  are cross-sectional views taken along lines XIIIa-XIIIa and XIIIb-XIIIb, respectively, in  FIG. 12 . 
     Referring to  FIGS. 12 ,  13 A and  13 B, a photosensitive negative-type green color resist similar to a resist used for the first green filter layers  21   a  is applied over the first green filter layers  21   a , the red filter layers  20 R and the blue filter layers  20 B. The photosensitive negative-type green color resist is applied to a thickness such that the combined green filter layer including the first and second green filter layers  21   a  and  21   b  will have a desirable thickness. 
     Then, an exposure process is performed using the same photomask as that used for the formation of the first green filter layers  21   a . The exposure conditions are selected so that the width of the second green filter layer  21   b  is smaller than that of the first green filter layer  21   a . Then, a development step is performed to form the second green filter layers  21   b.    
     The second green filter layer  21   b  is formed as described above on the first green filter layer  21   a  with a smaller width than that of the first green filter layer  21   a , with the edge portions of the red filter layers  20 R and the blue filter layers  20 B being interposed between the first green filter layers  21   a  and the second green filter layers  21   b.    
     Then, although not shown in the figure, the third transparent flattening layer  19   c  is formed so that the microlenses  22  can be formed precisely. A thermosetting transparent resin whose main component is an acrylic resin, for example, is applied on the color filter  20 , including the green filter layers  20 G, the red filter layers  20 R and the blue filter layers  20 B, and the applied resin is cured by baking using a hot plate, or the like. The process is repeated a plurality of times to thereby form the third transparent flattening layer  19   c , thus flattening the upper surface of the color filter  20 . Then, in order to shorten the distance to the surface of the color filter  20  for the purpose of improving the sensitivity and also improving the dependency on the angle of incidence, the third transparent flattening layer  19   c  is etched to be as thin as possible by a known etch-back process. 
     Then, a photosensitive positive-type resist whose main component is a phenol resin is applied on the third transparent flattening layer  19   c  in positions above the photoelectric transducers  13 , and an exposure and development process (including bleaching and baking) is performed, thereby forming the microlenses  22  each having a convex upper surface. The transmittance of the microlenses  22  is increased by ultraviolet irradiation. It is preferred that the post-baking of the microlenses  22  is performed at a temperature of 200° C. or less in order to prevent deterioration of the spectral characteristics of the color filter  20 . 
     The solid-state imaging device  10  as shown in  FIGS. 1 ,  2 A and  2 B is manufactured through steps as described above. 
     By the method for manufacturing a solid-state imaging device of the present embodiment, the green filter layer  20 G is formed by two layers of the first green filter layer  21   a  and the second green filter layer  21   b , with the edge portion of the red filter layer  20 R and the blue filter layer  20 B being interposed therebetween, thus forming a sandwich structure. Therefore, it is possible to prevent the formation of a gap between pixels, enabling the production of stable color filters. Thus, it is possible to prevent an oblique light beam incident on a pixel boundary portion from causing mixture of colors with adjacent color filter layers, and to eliminate the sensitivity non-uniformity. Moreover, it is possible to improve the optical characteristics such as line noise and color non-uniformity. 
     Moreover, with the green filter layer  20 G being in a two-layer structure, it is possible to prevent the formation of a gap between pixels and to reduce the height and angle of the rise of the edge portion of the red filter layer  20 R and the blue filter layer  20 B formed on the first green filter layer  21   a , whereby it is possible to shorten the distance from the lower surface of the microlens  22  to the photoelectric transducer  13 . Therefore, it is possible to obtain a high-definition image with the solid-state imaging device. 
     Moreover, since the color filter layers can be formed with thin peripheral portions, it is possible to form the color filter  20  with a high precision. Therefore, it is possible to prevent color non-uniformity between pixels, and to improve line noise and color shading of the solid-state imaging device. 
     Moreover, the first green filter layers  21   a  and the second green filter layers  21   b  can be formed by using the same photomask. Thus, the characteristic structure of the solid-state imaging device of the present embodiment can be realized while suppressing an increase in the manufacturing cost. 
     The solid-state imaging device of the present embodiment and the method for manufacturing the same are not limited to the embodiment described above, but can be realized in various other embodiments without departing from the scope of the present invention. 
     For example, while the present embodiment is directed to a color filter of the primary color scheme for use in a solid-state imaging device where a higher priority is placed on the color tone, the present invention may be applied to a color filter of the complementary color scheme for use in a solid-state imaging device where a higher priority is placed on the resolution and the sensitivity. In the complementary color scheme, magenta, green, yellow and cyan light color filter layers are formed in a predetermined pattern according to a known color arrangement. 
     While color filter layers are formed in the present embodiment by using a resist containing a dye or a pigment prepared so that light of a predetermined wavelength is selectively transmitted, the resist containing a dye or a pigment may be a known dye-added color resist, a known pigment-dispersed color resist, or the like, or may be a combination of these resists. 
     Moreover, instead of using a photosensitive transparent resin and a known photolithography process, the first transparent flattening layer  19   a  may be formed by repeatedly applying a thermosetting transparent resin material and thermally curing the applied resin material, followed by an etch-back process of a known method. 
     While the second transparent flattening layer  19   b  is formed for the purpose of improving the adhesion of the color filter, it may be omitted as long as a sufficient adhesion strength is ensured. 
     The present embodiment of the invention is also applicable to a structure where an upward convex lens or a downward convex lens is formed on the photoelectric transducer  13  to further reinforce the light-collecting property. 
     The present embodiment of the invention is also applicable to a structure where a photomask which has been subjected to an exit pupil correction depending on the application is used for the formation of the color filter and the microlenses  22 . 
     While the present embodiment is directed to a CCD-type solid-state imaging device, the present embodiment of the invention is also applicable to solid-state imaging devices of an amplification type such as a MOS type, or any other suitable type of solid-state imaging devices. 
     As described above, with the solid-state imaging device of the present invention and the method for manufacturing the same, it is possible to precisely form a color filter while preventing the exfoliation of color filter layers and the formation of a gap therebetween. Thus, the present invention is useful for a color solid-state imaging device including a color filter, a method for manufacturing the same, etc.