JP2006269775A - Imaging device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the variation of the structure of a boundary of filters in respective colors of a color filter of an imaging device. <P>SOLUTION: A G color resist where green pigments are dispersed is applied to a flat film 104, and irradiated with exposure light to be developed to form G filters 103G of prescribed plane patterns. Next, a positive R color resist 113R where red pigments are dispersed is applied to the whole surface of the flat film 104 covering the G filters 103G, and irradiated with exposure light to be developed to form R filters 103R adjacently to the G filters 103G. The R color resist 113R is exposed using a mask having a light shielding part whose edge is positioned at a position entering area where the G filters 103G are formed from edges of the G filters 103G at boundaries with the G filters 103G in respective areas forming the R filters 103R. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device having a color filter for capturing a color image and a manufacturing method thereof.

  Conventionally, it is known to use a solid-state imaging device for capturing a color image in a video camera, a still camera, or the like. FIG. 11 is a cross-sectional view of a conventional solid-state imaging device.

  This solid-state imaging device has a plurality of pixel units, photoelectric conversion units 910 that generate signal charges according to the amount of incident light are formed on the semiconductor substrate 900 in a grid pattern, and each photoelectric conversion unit 910 includes each pixel. Assigned to the department. Each pixel portion is provided with a gate electrode 909 and wiring layers 905 and 907 of a transistor for processing a signal generated by the photoelectric conversion portion 910 and interlayer insulating films 906 and 908 therebetween.

A color filter 903 is provided on the uppermost wiring layer 905 with a first planarizing film 904 interposed therebetween. The color filter 903 is a multi-color filter (hereinafter referred to as a color including a pigment of each color) made of a material including one of the three primary color pigments of red (R), green (G), and blue (B). The filters are referred to as R filters, G filters, and B filters, respectively, arranged in a predetermined pattern, and function to split incident light. It is known that these color filters are arranged in a pattern called a Bayer array as shown in FIG. 12 so that any one of R, G, and B filters is provided in each pixel portion ( In FIG. 12, the shaded portion indicates the G filter, the hatched portion extending diagonally downward to the right indicates the B filter, and the shaded portion extending diagonally downward to the left indicates the R filter. The same applies to the plan view.)
On the color filter 903, a micro lens 901 is provided for each pixel portion with a second planarization film 902 interposed therebetween. The microlens 901 functions to collect incident light on each photoelectric conversion unit 910.

  In order to form the Bayer array color filter 903, a photolithography technique is usually used. FIG. 13 is a side cross-sectional view showing the procedure for forming the color filter 903 of the conventional example.

  When forming the color filter 903, first, a negative G color resist in which, for example, a green (G) pigment is dispersed is applied to the surface of the first planarization film 904. Subsequently, using a mask in which a light shielding portion is formed in a region excluding the position where the G filter 903 is to be formed, for example, ultraviolet rays having a wavelength of 365 nm are irradiated and developed. In this way, as shown in FIG. 13A, the G filter 903G is formed on the first planarizing film 904 with a predetermined pattern. The pattern dimension of the G filter 903G is, for example, 7.0 μm at the bottom portion (the portion on the first planarization film 904 side). In the manufacture of the color filter 903 using the photolithography technique in the pixel portion of the recent solid-state imaging device having a width of about several microns in this way, in order to realize accurate development, it is called a reduction projection exposure apparatus, so-called stepper. An exposure apparatus is used.

  Next, as illustrated in FIG. 13B, a negative R color resist 913 </ b> R in which a red (R) pigment is dispersed is applied to the entire surface of the first planarization film 904. At this time, the G filter 903G is covered with the R color resist 913R. Subsequently, using a mask in which a light shielding portion is formed in a region excluding the position where the R filter 903R is to be formed, for example, ultraviolet rays having a wavelength of 365 nm are irradiated and developed. Thereby, as shown in FIG. 13C, an R filter 903R is formed adjacent to the G filter 903G.

Thereafter, the B filter is similarly formed in a predetermined pattern. As a result, a color filter 903 in which R, G, and B filters are arranged in a predetermined pattern is formed.
JP-A-5-6849 JP-A-10-209410

  In the above-described conventional method for manufacturing a solid-state imaging device, for example, when the R filter 903R is formed in a region surrounded by the previously formed G filter 903G as in the example shown in FIG. 13, the R filter 903R is surrounded by the G filter 903G. Development is performed by irradiating with ultraviolet rays using a mask in which a transmission part having a width equal to the width of the region, that is, in the above example, a 7.0 μm wide transmission part is formed. In this case, since the R color resist 913R to be the R filter 903R is formed so as to cover the G filter 903, the R color resist 913R is raised at the edge of the region surrounded by the G filter 903G. As a result of being developed by being irradiated with ultraviolet rays, the edge portion of the R filter 903R in contact with the G filter 903G has a slightly raised shape as shown in FIG.

  Further, since the resolution of the color filter material is limited in the above-described method for manufacturing a solid-state imaging device, when forming a fine pattern, the corners of the color filter 903 have an arc shape as shown in FIG. Become. When the corners are arcuate in this way, gaps in which no color filters are formed are formed in the corners.

  On the other hand, in the manufacture of the color filter 903 using the photolithography technique as described above, the manufacturing process has some variation, that is, the size and position of the mask, the distortion component of the exposure apparatus, the exposure amount and the exposure amount in each exposure shot. Variations in the in-plane distribution, alignment position, resist characteristics, etc. are inevitable. For this reason, the bulge-shaped portion and the gap as described above vary in dimensions and the like.

  Further, when the size of the transmission part of the mask is increased or the irradiation energy of ultraviolet rays is increased, as shown in FIG. 13D, the edge of the R filter 903R rides on the edge of the G filter 903G. Sometimes. On the other hand, when the dimension of the transmission part of the mask is reduced, a gap may be formed between the G filter 903G and the R filter 903R at portions other than the corners as shown in FIG. .

  Further, in the conventional method for manufacturing a solid-state imaging device, when forming the R filter 903R, there is a case where ultraviolet rays are irradiated using a mask having a transmission part slightly narrower than the width of the region surrounded by the G filter 903G. . Also in this case, an overlap or a gap may be formed between the G filter 903G and the R filter 903R due to variations in the manufacturing process.

  Such variations such as the raised shape, overlap, and gap between the filters of each color affect the captured image. That is, as incident light to the solid-state imaging device, in addition to what is incident on each microlens 901 as indicated by an arrow a in FIG. 11, as indicated by an arrow b, a boundary between microlenses 901, that is, a boundary between pixel portions. Is incident on the. As indicated by an arrow a, incident light incident on each microlens 901 is collected by the microlens 901 toward the photoelectric conversion unit 910, and is planarized films 902, 904, a color filter 903, interlayer insulating films 906, 908, and the like. The light that has passed through and reaches the photoelectric conversion unit 910 and thus condensed light becomes an input signal that has a dominant influence on the output signal of the photoelectric conversion unit 910. On the other hand, as shown by the arrow b, the light incident on the boundary between the pixel portions causes scattering, reflection, refraction, diffraction, and the like at the boundary of each color filter and the wiring layer of the color filter 903. A part of the components reaches the photoelectric conversion unit 910 and slightly affects the output signal of the photoelectric conversion unit 910.

  For example, if there is a gap at the boundary between the filters of each color, the absolute amount of light that enters beyond the color filter 903 portion is about three times that when a color filter is present in the gap. For this reason, when the width of the gap changes, the amount of light that enters the boundary between the pixel portions and reaches the photoelectric conversion portion due to scattering, reflection, refraction, diffraction, or the like changes.

  On the other hand, in the overlapping portion of the filters of each color, the two filters overlap and the light passes through the thickened portion, so the absolute amount of light entering beyond the color filter 903 portion is reduced, and again The amount of light reaching the photoelectric conversion unit among the light incident on the boundary between the pixel units changes according to the change in the overlap amount. Moreover, the mixed light reaches the photoelectric conversion unit by passing through the overlapping portions of adjacent filters of different colors.

  In addition, the overlap or gap between the filters of each color may affect the second planarization film 902 formed on the color filter 903. That is, as shown in FIG. 14B, when a gap is generated between the R filter 903R and the G filter 903G, the surface of the planarizing film 902 formed thereon is formed on the planarizing film. In order to enter the gap when the member forming 902 is applied, a minute recess may be formed. On the other hand, as shown in FIG. 14C, when the R filter 903R rides on the G filter 903G, a minute convex portion may be formed on the surface of the planarizing film 902. Thus, when convex portions or concave portions are formed on the surface of the planarizing film 902, the path of incident light changes due to the refraction of light on the surface of the planarizing film 902. This also affects the captured image. For example, the concave portion on the surface of the planarizing film 902 acts like a lens to disperse incident light, and as a result, out of the light incident on the boundary between the pixel portions, the concave portion disperses the photoelectric conversion. An optical component that reaches the unit 910 may be generated, thereby affecting the output signal of the photoelectric conversion unit 910.

  In this way, due to variations in the manufacturing process, the structure between the filters of each color, particularly gaps and overlaps, will vary, so that even if light from the subject is incident under the same conditions, it will be incident on the photoelectric conversion unit. Thus, the absolute amount of light that is different for each pixel portion. Further, depending on the pixel portion, a mixed color component and a shading component are included. Such variations in the amount of incident light, color mixing components, and shading components may occur between pixels in one chip due to the dimensional accuracy of the mask, and the mask position and exposure amount between exposure shots. Due to variations, it may occur between multiple chips.

  In the case of a general solid-state imaging device, the chip size is within a range (field size) that can be exposed by a single exposure shot by an exposure apparatus, and a pattern of the entire chip is formed by a single exposure process. . In this case, the gaps and overlaps between the color filters as described above tend to occur in a form that continuously changes two-dimensionally within the chip surface. For this reason, the light quantity of the incident light to the photoelectric conversion unit 910 changes in a form having a two-dimensional distribution in the chip surface. As a result, in the output image signal, there is a tendency that shading components and color mixing components corresponding to the width of the gap between the filters and the overlap amount are included in a form having a two-dimensional distribution on the image plane. In addition, the influence on the captured image tends to be large, such as a boundary portion having a difference in brightness corresponding to the distribution.

  On the other hand, in a solid-state imaging device having a large chip size, the imaging region may be larger than the field size of the exposure apparatus. In this case, the imaging region is divided into a plurality of exposure regions (regions that are exposed by one exposure shot). It is known to employ a technique (divided exposure method) in which exposure is performed for each of the divided exposure areas, and the pattern formed by each exposure is joined to form a pattern of the entire imaging area. (See Patent Document 1). In the solid-state imaging device formed by the division exposure method in this way, the variation in the manufacturing process at the time of forming the color filter described above varies between exposure shots. Variations occur in the structure of the boundary between the filters of each color. As a result, the influence on the captured image tends to be further increased, such as a difference in brightness between the borders of the exposure areas.

  In recent years, in a video camera or the like, the definition of a captured image has been increased, and accordingly, the influence of the color filter 903 on the captured image due to the variation in the structure of the boundary of each color filter is affected. Further reduction is desired. That is, in order to increase the definition of a captured image, in a solid-state imaging device, the integration of pixels is advanced, and accordingly, even a small variation in the amount of light causes a significant effect on the captured image. Therefore, it is expected that by suppressing the variation, it can greatly contribute to the improvement of the image quality of the captured image.

  In this regard, the structure of the color filter 903, such as an overlap or a gap at the boundary between the filters of each color, is mainly caused by the exposure process as described above. Therefore, the amount of overlap and gaps can be reduced by increasing the accuracy of the mask size used for exposure, correcting mask misalignment, or correcting the exposure energy difference in each exposure area, and making the characteristics of the resist that becomes the color filter uniform. Is possible. However, it is impossible to completely suppress the variation in the manufacturing process to zero, and there is a limit in suppressing the variation in the structure of the boundary portion of each color filter by such a method.

  The present invention has been made to solve the above-described problems of the prior art, and the structure of the boundary portion of each color filter generated when a color filter is formed by a general photolithography technique. An object of the present invention is to provide a solid-state imaging device capable of reducing the variation of the image quality and improving the image quality of a captured image, and a manufacturing method thereof.

  In order to achieve the above object, a method for manufacturing a solid-state imaging device according to the present invention includes a solid filter having a color filter in which a plurality of color filters are arranged in a predetermined plane pattern so that filters of different colors are adjacent to each other. A method of manufacturing an image pickup device, comprising: applying a color resist of a first color on a predetermined film, irradiating with exposure light, and developing to form a first color filter having a predetermined plane pattern; The positive color resist of the second color to be the second color filter formed adjacent to the first color filter is applied to the region including the region for forming the second color filter. And coating the first color filter, irradiating and developing exposure light to form a second color filter, and exposing the second color resist to the second color. Of the first color in each region forming the filter of In the boundary between the filter, than the first edge color filter, a method of first edge in a position that has entered the color filters are formed within regions carried out using a mask having a shielding portion positioned.

  According to the present invention, it is possible to reduce the occurrence of variations in the structure of the boundary portion between the filters of each color of the color filter due to variations in the manufacturing process. As a result, the amount of incident light on the photoelectric conversion unit due to gaps or overlaps between the filters of each color varies among the photoelectric conversion units, in particular, such that the incidence changes continuously two-dimensionally within the imaging region. It is possible to suppress fluctuations in the amount of light and to suppress the occurrence of shading components and color mixing components due to gaps and overlaps between the filters of each color in the pixel signal output from the photoelectric conversion unit. Can be improved. Further, even when the color filter is formed by using the divided exposure method, it is possible to suppress variations in the filter structure between the exposure regions, and unevenness occurs in the captured image in a portion corresponding to each exposure region. Can be reduced.

(First embodiment)
FIG. 2 is a side sectional view showing the structure of the solid-state imaging device according to the first embodiment of the present invention.

  The solid-state imaging device includes a photoelectric conversion unit 110 that is formed in the vicinity of the surface of the semiconductor substrate 100 and generates a signal charge corresponding to the amount of incident light. The photoelectric conversion units 110 are arranged in a lattice pattern, and one photoelectric conversion unit 110 is provided for each of the plurality of pixel units.

  In each pixel unit, a pixel signal corresponding to the signal charge generated in the photoelectric conversion unit 110 is generated, and a horizontal scanning circuit (in accordance with a control signal from a vertical scanning circuit (not shown) provided at the edge of the solid-state imaging device). A drive circuit for transferring a pixel signal to (not shown) is formed. On the semiconductor substrate 100, a gate electrode 109 of a transistor constituting this drive circuit is formed for each pixel portion, and a plurality of wiring layers are formed thereon according to the circuit configuration of the drive circuit. In the example shown in FIG. 8, two wiring layers 105 and 107 are formed.

In the wiring layers 105 and 107, wiring obtained by patterning aluminum (Al) or the like into a desired shape is formed. The gate electrode 109 and the wiring layers 105 and 107 are insulated by interlayer insulating films 106 and 108 made of, for example, SiO ₂ . In addition, a diffusion layer (not shown) serving as a source / drain of the transistor is formed under the gate electrode 109 of the semiconductor substrate 100.

  On the uppermost wiring layer 105, a first planarization film 104 made of, for example, acrylic resin is formed so as to cover the wiring. On the first planarization film 104, a color filter 103 for separating incident light is provided corresponding to each pixel. The color filter 103 has filters of each color formed using a photoresist containing pigments of three primary colors of red (R), green (G), and blue (B). It is arranged so that one color filter covers the part. A second planarizing film 102 is formed on the color filter 103, and a microlens 101 is formed thereon as a condensing lens for condensing incident light on the photoelectric conversion unit 110.

  In the solid-state imaging device of the present embodiment, the pixel pitch is, for example, 7 μm. The color filter 103 may have a configuration in which a Bayer array is provided in the same manner as the conventional solid-state imaging device shown in FIG.

  Next, a method for manufacturing a color filter of the image sensor of the present embodiment will be described with reference to FIG. FIG. 1 shows the manufacturing method of the present embodiment, taking as an example the procedure of first forming the G filter 103G and forming the R filter 103R between the G filters 103G. In the same procedure, a B filter (not shown) can be formed between the G filters 103G. Also, when the G filter 103G is formed after forming the R filter 103R and the B filter, the same procedure is performed. Can be used. As for the manufacturing method of the other components of the solid-state imaging device excluding the color filter 103, any known manufacturing method may be used as long as an optimum shape or the like can be obtained for each component. Then, detailed explanation is omitted. The same applies to the following embodiments.

  To form the G filter 103G, first, for example, a positive G color resist in which a green (G) pigment is dispersed is applied to the surface of the first planarization film 104. Subsequently, using a mask in which a light shielding portion is formed at a position where the G filter 103G is to be formed, for example, ultraviolet rays having a wavelength of 365 nm are irradiated and developed. As a result, a G filter 103G having a predetermined pattern is formed on the first planarization film as shown in FIG. At this time, the pattern dimension of the G filter 103G is 7.0 μm in the bottom portion (first planarization film 104 side) in this embodiment. The exposure may be performed with one exposure shot for the entire solid-state imaging device, or may be performed by a divided exposure method.

  Next, as shown in FIG. 1B, a positive R color resist 113R in which a red (R) pigment is dispersed is applied to the entire surface of the first planarizing film 104 so as to cover the G filter 103G. Apply. Subsequently, for example, ultraviolet rays having a wavelength of 365 nm are irradiated using a mask in which a light shielding portion is formed at a position where the R filter 103R is to be formed.

  At this time, in the method of manufacturing the solid-state imaging device of the present embodiment, the R filter 103R is formed so that no gap is formed between the R filter 103R and the G filter 103G even if the mask is displaced. A mask in which a light-shielding portion is formed in a region that should be, that is, a region slightly wider than a region surrounded by the G filter 103G is used. As an example, the light-shielding portion is 7.2 μm square so that each side thereof is located 0.1 μm away from the edge of the region surrounded by the G filter 103G.

  In this case, when the ultraviolet irradiation energy is small, after development, the R filter 103R is formed in a region corresponding to the light shielding portion of the mask, and as a result, as shown in FIG. The G filter 103G is formed on the edge of the G filter 103G. However, when the ultraviolet irradiation energy is increased, the region where the R filter 103R is formed becomes narrower than the region corresponding to the light shielding portion of the mask (overexposure). In this way, as shown in FIG. 1D, the dimension of the R filter 103R gradually decreases as the irradiation energy increases, and the position of the edge of the R filter 103G moves toward the edge portion of the G filter 103G. And move. When the irradiation energy of the ultraviolet rays is further increased, the height of the raised portion generated at the edge portion of the G filter 103G becomes lower as the irradiation energy increases, as shown in FIG. When the irradiation energy of ultraviolet rays is further increased, the R filter 103R is formed so as to be isolated within the region surrounded by the G filter 103G (not shown).

  Therefore, if the ultraviolet irradiation energy is set appropriately, the R filter 103R does not ride on the G filter 103G as shown in FIG. 1E, and an appropriate pattern that does not create a gap with the G filter 103G. Can be formed. At this time, in the formed R filter 103R, the size of the portion that rides on the G filter 103G decreases in a manner that is approximately proportional to the amount of increase in ultraviolet irradiation energy. On the other hand, when the edge of the formed R filter 103R is in the vicinity of the region in contact with the G filter 103G, the thickness of the applied R color resist 113R is thicker than other portions. Therefore, the change rate of the planar dimension of the formed R filter 103R with respect to the increase amount of the irradiation energy of the ultraviolet ray is smaller than that of the portion on the G filter 103G. In other words, in the vicinity of the region where the edge of the formed R filter 103R is in contact with the G filter 103G, the increase or decrease in irradiation energy appears in the form of a change in the height of the edge portion of the formed R filter 103R. Changes in the planar dimensions are suppressed.

  Therefore, according to the present embodiment, it is possible to optimize the ultraviolet irradiation energy with a sufficient margin, that is, by setting the ultraviolet irradiation energy appropriately, there is some variation in the irradiation energy. In addition, the R filter 103R can be formed in a pattern that hardly causes the R filter 103R to ride on the G filter 103G and the gap with the G filter 103G.

  At this time, when the size of the formed R filter 103R decreases as the energy irradiated during exposure increases, the reduction rate of the planar size after the stage where the R filter 103R comes into contact with the edge of the G filter 103G. In other words, the suppression of R means that the size of the R filter 103R is defined by the shape and size of the previously formed G filter 103G. Therefore, in the solid-state imaging device manufacturing method of this embodiment, in addition to the exposure irradiation energy variation, the mask size and position, the exposure device distortion component, the in-plane distribution of the exposure amount and the exposure amount in each exposure shot, and the alignment Even if there are other variations in the manufacturing process, such as position and resist characteristics, the size and position of the R filter 103R are defined by the pattern of the adjacent G filter 103G formed earlier, so that overlap and gaps occur. Therefore, the color filter 103 can be formed stably.

  As described above, according to the present embodiment, in a color filter in which a plurality of color filters are arranged in a grid-like plane pattern, it is possible to suppress the occurrence of an overlap or a gap between the filters of each color. As a result, the amount of incident light on the photoelectric conversion unit due to gaps or overlaps between the filters of each color varies among the photoelectric conversion units, in particular, such that the incidence changes continuously two-dimensionally within the imaging region. It is possible to suppress fluctuations in the amount of light and suppress the occurrence of shading components and color mixing components in the pixel signal output from the photoelectric conversion unit, and as a result, the image quality of the captured image can be improved.

  In addition, by applying this embodiment when using the divided exposure method for manufacturing color filters, even if there are variations in the manufacturing process between exposure shots, it is possible to suppress variations in the filter structure between exposure regions. it can. Thereby, it is possible to reduce the occurrence of unevenness in the captured image in a portion corresponding to between the exposure regions.

  The present inventor fabricated a solid-state imaging device according to the present example and performed imaging. As a result, there are very few shading components and color mixing components in the captured image, and even if the divided exposure method is used in the color filter manufacturing process, the captured image can be visually confirmed at the part corresponding to the boundary of each exposure region. No streak-like image unevenness was observed.

(Second embodiment)
FIG. 3 is a cross-sectional view showing the manufacturing procedure of the color filter of the solid-state imaging device according to the second embodiment of the present invention. Note that the solid-state imaging device shown in FIG. 3 may have a configuration in which the pixel pitch is 7 μm and the color filters are arranged in a Bayer array, as in the first embodiment. Further, the configuration of the solid-state imaging device other than the color filter may be the same as that of the first embodiment, and detailed description thereof is omitted.

  Also in this embodiment, in forming the color filter, first, for example, a positive G color resist in which a green (G) pigment is dispersed is applied to the surface of the first planarization film 304. Subsequently, development is performed by irradiating, for example, ultraviolet light having a wavelength of 365 nm using a mask in which a light shielding portion is formed at a position where the G filter 303G is to be formed. As a result, as shown in FIG. 3A, a G filter 303G is formed in a predetermined pattern on the first planarization film.

  In the present embodiment, when the G filter 303G is exposed, ultraviolet rays are irradiated so as to have an illuminance distribution. That is, exposure is performed by reducing the exposure contrast at the edge portion of the area to be exposed, whereby the edge of the G filter 303G becomes tapered as shown in FIG. At this time, the G filter 303G has a bottom portion (on the first planarization film 304 side) having a predetermined size that is slightly larger than the pixel pitch. In this embodiment, the size of the bottom portion is set to 7.2 μm so as to be 0.1 μm larger on both sides than the pixel pitch of 7 μm.

  As a method of reducing the exposure contrast at the edge of the exposure region, a method of shifting the focus of the exposure light from the mask surface can be used. Alternatively, the exposure contrast at the edge part of the exposure region can be lowered by changing the transmittance at the edge of each light shielding part of the mask stepwise to give gradation to the optical density of incident light through the mask. Good results can be obtained.

  Next, as shown in FIG. 3B, a positive type R color resist 313R in which a red (R) pigment is dispersed is applied to the entire surface of the first planarization film 304 so as to cover the G filter 303G. Apply. Subsequently, for example, ultraviolet rays having a wavelength of 365 nm are irradiated using a mask in which a light shielding portion is formed at a position where the R filter 303R is to be formed.

  At this time, also in this embodiment, exposure is performed using a mask having a light shielding portion wider than a region where the R filter 303R is to be formed. Specifically, a mask in which a 7.2 μm square light shielding portion that is 0.1 μm larger on both sides than the pixel pitch 7 μm is used, and the edge of the light shielding portion is surrounded by the G filter 303G (on the bottom side). Exposure is performed by arranging a mask so as to be 0.2 μm away from the edge of the 6.8 μm square region.

  In this case, when the ultraviolet irradiation energy is small, after development, the R filter 303R is formed on the (upper) edge of the G filter 303G as shown in FIG. On the other hand, as a result of overexposure, the dimension of the R filter 303R gradually decreases with increasing irradiation energy as shown in FIG. 3D, and the position of the edge of the R filter 303G becomes the edge of the G filter 103G. Move to the partial side. By increasing the irradiation energy of the ultraviolet rays and optimizing the irradiation energy as in the first embodiment, as shown in FIG. 1E, the (upper) edge of the R filter 303R to be formed is formed. However, it is possible to make the position substantially coincident with the (upper) edge of the G filter 303R.

  In the present embodiment, the edge of the formed R filter 303R has a reverse taper shape in accordance with the taper shape of the edge of the G filter 303G, and the edge portion of the R filter 303R and the edge portion of the G filter 303G are the filter surface. They overlap each other when viewed in the direction perpendicular to the filter (thickness direction of the filter). As a result, even if the position of the (upper) edge of the formed R filter 303R slightly enters the formation area of the R filter 303R from the position of the (upper) edge of the G filter 303G, it is in the region between these edges. The G filter 303G exists and does not form a complete gap. As a result, the formation of a gap between the R filter 303R and the G filter 303G can be more effectively suppressed. As described above, in order to suppress the occurrence of a gap between adjacent filters, the overlapping amount of the tapered portion of the edge between adjacent filters is preferably 0.1 μm or more, and is preferably 0.2 μm or more. More desirable.

  In the present embodiment, the edge of the G filter 303G is formed in a tapered shape, so that when the R filter 303R is formed, even if there is local deformation or the like in the edge of the G filter 303G, Defects such as voids are less likely to occur at the boundary portion of the R filter 303R.

  In addition, since it is possible to suppress the occurrence of an overlap or gap at the boundary between the R filter 303R and the G filter 303G, as shown in FIG. 4, when the second planarization film 302 is formed on the color filter, the surface thereof is formed. Protrusions and recesses can also be suppressed. That is, as shown in FIG. 4A, if there is no overlap or gap at the boundary between the R filter 303R and the G filter 303G, the surface of the color filter is substantially flat even at this boundary, and as a result, The surface of the planarization film 302 can be easily planarized. Further, as shown in FIGS. 4B and 4C, the R filter 303R is shaped like riding on the G filter 303G, or the position of the (upper) edge of the R filter 303R is ( Even when the R filter 303R is entered from the position of the edge on the upper side, as described above, the amount of overlap and the shift width can be kept relatively small. There is almost no unevenness on the surface. This also applies to the first embodiment. According to the first and second embodiments, when the second planarization film is formed on the color filter, the surface is prevented from being uneven. The effect is obtained. At this time, in the second embodiment, even when the position of the (upper) edge of the R filter 303R enters the R filter 303R formation region side from the position of the (upper) edge of the G filter 303G, Since the G filter 303G exists in this area, the unevenness formed on the surface of the color filter, and hence the unevenness formed on the surface of the second planarization film can be further reduced.

  Thus, by suppressing the formation of irregularities on the surface of the second planarization film, the amount of incident light reaching the photoelectric conversion unit due to the irregularities on the surface of the second planarization film can be reduced. It is possible to suppress the variation between the two and contribute to the improvement of the image quality.

  As described above, also in this embodiment, it is possible to suppress the occurrence of overlap and gaps between the filters of the respective colors constituting the color filter, and in particular, it is possible to effectively suppress the generation of gaps. This is the same regardless of whether each color filter is formed by a single exposure shot or when the divided exposure method is used. As shown in FIG. 5, the structure between filters of each color over the entire area of the solid-state imaging device. Can form a substantially uniform color filter. As a result, the disturbance of the captured image that continuously changes two-dimensionally within the exposure region, and the occurrence of unevenness in the captured image that occurs at the boundary portion of the exposure region when using the divided exposure method, The image quality of the captured image can be improved.

  In this embodiment, the edge of each color filter does not need to be tapered or inversely tapered, and may be any shape as long as the edge portions of adjacent filters overlap each other, that is, between adjacent filters. It is possible to effectively suppress the occurrence of a gap in the surface. As such a modification, the edge portions of the filters of the respective colors may be wedge-shaped in cross section as shown in FIGS. 6 (a) and 6 (b), for example. In such a configuration, as shown in FIGS. 7A and 7C, first, for example, the edge portion of the G filter 303G is formed in a wedge shape, and thereafter, as shown in FIGS. 7B and 7C. As shown, it can be obtained by forming, for example, an R filter 303R in the same manner as the above procedure. Thus, in order to form the edge portion of the G filter 303G in a desired shape such as a wedge shape, in the exposure of the color resist, a method of changing the exposure contrast at the edge portion of the exposure region, and / or during development, A technique that utilizes the difference in the dissolution characteristics of the resist in the depth direction with respect to the developer can be used.

(Third embodiment)
FIG. 8 is a cross-sectional view showing the manufacturing procedure of the color filter of the solid-state imaging device of the third embodiment of the present invention. Note that the solid-state imaging device shown in FIG. 8 may have a configuration in which the pixel pitch is 7 μm and the color filters are arranged in a Bayer array, as in the first embodiment. Further, the configuration of the solid-state imaging device other than the color filter may be the same as that of the first embodiment, and detailed description thereof is omitted.

  Also in this embodiment, first, a positive G color resist in which, for example, a green (G) pigment is dispersed is applied to the surface of the first planarizing film 604, and then a position where a G filter 603G is to be formed. The G filter 603G is formed by irradiating, for example, ultraviolet rays having a wavelength of 365 nm using a mask having a light shielding portion formed thereon, and developing the same as in the previous embodiments. At this time, in this embodiment as well, as in the second embodiment, ultraviolet rays are irradiated so as to have an illuminance distribution during the exposure of the G filter 603G, and the edge portion is tapered as shown in FIG. The G filter 603G is formed so that The pattern size of the G filter 603G is also 7.2 μm at the bottom part (the first planarization film 604 side) as in the second embodiment.

  Next, as shown in FIG. 8B, a positive type R color resist 613R in which a red (R) pigment is dispersed is applied to the entire surface of the first planarizing film 604 so as to cover the G filter 603G. Application is performed, and ultraviolet rays having a wavelength of 365 nm, for example, are irradiated using a mask in which a light shielding portion is formed at a position where the R filter 603R is to be formed. At this time, as in the second embodiment, the width of the region surrounded by the G filter 603G is 6.8 μm, and in this embodiment as well, 0.2 μm away from the edge (on the bottom side) of the 6.8 μm square region. A mask on which a 7.2 μm square light-shielding portion with an edge at the position is formed is used. Further, in this embodiment, ultraviolet rays are irradiated so as to have an illuminance distribution in a region that forms the R filter 603R and is surrounded by the G filter 603G. In other words, exposure is performed with the exposure contrast at the edge of each area to be exposed lowered.

  After development, when the irradiation energy of ultraviolet rays is small, the formed R filter 603R is formed so as to partially ride on the G filter 603G as shown in FIG. As shown in d), the edge of the R filter 603R approaches the edge of the G filter 603G as in the previous embodiment. Similarly, the rate of change in the edge position of the formed R filter 603R decreases as the irradiation energy increases near the edge of the G filter 603G. Therefore, by utilizing this, the irradiation energy can be optimized, and as shown in FIG. 8E, it is possible to hardly get on the boundary between the G filter 603G and the R filter 603R and generate almost no gap.

  In the present embodiment, since the edge of the R filter 603R is also formed in a tapered shape, it is possible to more effectively reduce the occurrence of a ride or a gap at the boundary between the G filter 603G and the R filter 603R. As a result, the disturbance of the captured image that continuously changes two-dimensionally within the exposure region, and the occurrence of unevenness in the captured image that occurs at the boundary portion of the exposure region when using the divided exposure method, The image quality of the captured image can be improved.

(Fourth embodiment)
FIG. 9 is a plan view of a color filter showing the configuration of the solid-state imaging device according to the fourth embodiment of the present invention.

  Unlike the side portions, the corner portions of the filters of the respective colors have low contrast during exposure, and the pattern shape is likely to change due to variations in the manufacturing process. In the present embodiment, as shown in FIGS. 9A to 9C, the corners of the filters of each color that reduce the exposure contrast are filled with any one of the filters of each color in contact with each corner. In this configuration, the gap is eliminated. 9A shows an example in which a G filter is formed at the corner, FIG. 9B shows an example in which a B filter is formed at the corner, and FIG. 9C shows an R filter at the corner. An example in which is formed is shown.

  In the production of the color filter of this embodiment, a positive type resist can be used as a resist used to form a filter pattern of a color that fills corners. The color filter having the above-described configuration can be formed by providing a fine light-shielding pattern that fills a portion corresponding to a corner portion in a mask used for exposure when forming a color filter that fills the corner portion.

  In this way, by filling each corner of each color filter with one of the filters, it is possible to reduce variations in the pattern shape due to variations in the manufacturing process at the corner. As a result, it is possible to suppress the occurrence of shading components and color mixing components in the captured image due to variations in the pattern shape at the corners, and in particular, it continuously changes two-dimensionally within the exposure region. Such disturbance of the captured image and occurrence of unevenness in the captured image occurring at the boundary portion of the exposure region when the divided exposure method is used can be suppressed, and the image quality of the captured image can be improved.

  In addition, this embodiment can be implemented in combination with the manufacturing method of the first to third embodiments, so that the structure of the pattern shape or the like can be obtained in the side portion or the corner portion of each color boundary in the color filter. Variations can be suppressed and the image quality of the captured image can be effectively suppressed.

(Application examples for digital cameras)
FIG. 10 shows an example of a circuit block of an example camera using the solid-state imaging device according to the present invention as the solid-state imaging device 1004. A shutter 1001 is provided in front of the taking lens 1002 and controls exposure. The amount of light is controlled by the diaphragm 1003 as necessary, and an image is formed on the solid-state imaging device 1004. A signal output from the solid-state imaging device 1004 is processed by a signal processing circuit 1005 and converted from an analog signal to a digital signal by an A / D converter 1006. The output digital signal is further processed by a signal processing unit 1007 to generate captured image data. The processed digital signal is stored in the memory unit 1010 or sent to an external device through the external I / F 1013. An image can also be recorded on the recording medium 1012, and for this purpose, the output digital signal is recorded through the recording medium control I / F unit 1011 controlled by the overall control / arithmetic unit. The solid-state imaging device 1004, the imaging signal processing circuit 1005, the A / D converter 1006, and the signal processing unit 1007 are controlled by a timing generation unit 1008, and the entire system is controlled by an overall control / arithmetic unit 1009.

FIG. 3 is a cross-sectional view showing the procedure for manufacturing the color filter of the solid-state image sensor of the first embodiment of the present invention. It is sectional drawing which shows the whole structure of an example solid-state image sensor in which the color filter of FIG. 1 was mounted. It is sectional drawing which shows the manufacture procedure of the color filter of the solid-state image sensor of 2nd Example of this invention. It is sectional drawing which expands and shows the principal part of the shape example of the color filter formed by the manufacturing procedure of FIG. It is a schematic diagram which shows the whole structure of the color filter formed by the manufacturing procedure of FIG. 3, (a) is a top view, (b), (c) is sectional drawing. It is sectional drawing which expands and shows the principal part of the shape example of the color filter which the solid-state image sensor of the modification of 2nd Example has. It is sectional drawing which shows the manufacture procedure of each color filter of FIG. It is sectional drawing which shows the manufacture procedure of the color filter of the solid-state image sensor of 3rd Example of this invention. It is a top view which shows the structure of the color filter of the solid-state image sensor of 4th Example of this invention. It is a block diagram which shows the structure of an example camera using the solid-state image sensor of this invention. It is a sectional side view which shows the structure of the solid-state image sensor of a prior art example. It is a schematic diagram which shows the whole structure of the color filter formed using the division | segmentation exposure method of a prior art example, (a) is a top view, (b), (c) is sectional drawing. It is sectional drawing which shows the manufacture procedure of the color filter of the solid-state image sensor of a prior art example. It is sectional drawing which expands and shows the principal part of the shape example of the color filter of the solid-state image sensor of a prior art example.

Explanation of symbols

103 color filter 103G G filter (first color filter)
103R R filter (second color filter)
113R R color resist (second color resist)

Claims (11)

A method of manufacturing a solid-state imaging device having a color filter in which a plurality of color filters are arranged in a predetermined plane pattern so that the filters of different colors are adjacent to each other,
Applying a color resist of a first color on a predetermined film, irradiating with exposure light and developing to form the filter of the first color of a predetermined plane pattern;
A positive-type second color resist that is the second color filter formed adjacent to the first color filter is applied to a region including a region for forming the second color filter. Coating the first color filter, irradiating with exposure light and developing to form the second color filter,
The exposure to the color resist of the second color is performed from the edge of the filter of the first color at the boundary with the filter of the first color in each region forming the filter of the second color. Using a mask having a light shielding portion where an edge is located at a position where the filter of the first color is formed,
Manufacturing method of solid-state image sensor.   2. The method of manufacturing a solid-state imaging device according to claim 1, wherein the exposure to the second color resist is performed by overexposure with irradiation energy larger than a standard at an edge of each exposure region.   At least one of an edge of each exposure region at the time of forming the first color filter and an edge of each exposure region at the time of forming the second color filter; The manufacturing method of the solid-state image sensor of Claim 1 or 2.   The focus position of the exposure light is shifted from the standard at least one of an edge of each exposure region when the first color filter is formed or an edge of each exposure region when the second color filter is formed. Item 4. A method for manufacturing a solid-state imaging device according to Item 3.   The transmittance of the edge portion of the light-shielding portion is stepwise at least one of the edge of each exposure region when the first color filter is formed or the edge of each exposure region when the second color filter is formed. The method for manufacturing a solid-state imaging device according to claim 3, wherein the exposure is performed using a mask changed to. The multi-color filter is a solid-state imaging device having a color filter configured to be arranged in a predetermined plane pattern so that the filters of different colors are adjacent to each other,
The edge of the filter of each color has a predetermined pattern in the thickness direction so that the edge portions of the filters of different colors adjacent to each other overlap each other in the thickness direction to have a predetermined thickness. Solid-state image sensor.   The solid-state imaging device according to claim 6, wherein the edge portion of the filter has a tapered shape in the thickness direction.   The solid-state imaging device according to claim 6, wherein a shape of an edge portion of the filter in a thickness direction is a wedge shape.   9. The solid-state imaging device according to claim 6, wherein the width of the portion where the edge portions of the filters of different colors adjacent to each other are combined in the thickness direction is 0.1 μm or more. . A multi-color filter is a solid-state imaging device having a color filter configured so that the filters of different colors are arranged adjacent to each other in a lattice pattern,
The solid-state image sensor in which the corner | angular part of each grid | lattice-like pattern of the said filter is filled with any one of the said filter of the color which touches the said corner | angular part.   An imaging system comprising: the solid-state imaging device according to any one of claims 6 to 10; and means for generating captured image data according to an output signal of the solid-state imaging device.

Images