JP2006078766A - Color solid-state imaging element and its color filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging element having a color filter which has spectroscopic characteristics having good color separation even under high luminosity photo-irradiation. <P>SOLUTION: In a color solid-state imaging element (14), at least green and red color filters (12 and 11) are formed on a plurality of photoelectric conversion elements. The green and the red color filters (12 and 11) respectively have a two layer constitution. Among the two layers, one layer is a common color filter layer (21 or 23) including yellow pigments or yellow dyes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color solid-state imaging device having a color filter, and more particularly to the structure of a color filter used therein.

  A solid-state imaging device mounted on a digital camera, a color scanner, a color copy, or the like usually has a plurality of photoelectric conversion elements formed on a semiconductor thin film formed on a surface layer or an insulating substrate of a semiconductor substrate. For example, a CCD or the like is used as the photoelectric conversion element, and a plurality of color filters, generally red, blue, and green filters, are arranged on the front surface of each photoelectric conversion element to achieve colorization.

  Examples of a method for forming a color filter include a pigment dispersion method, a dyeing method, and a dye dispersion method (see, for example, Patent Documents 1 to 5). Each of these methods employs a method of patterning a primary color (red, blue, green) or complementary color (cyan, magenta, yellow) color resist by lithography.

  A color filter obtained by a dyeing method using a dye or a dye dispersion method has a problem in heat resistance and light resistance. For this reason, it is not suitable for a line image sensor mounted on, for example, a color copy, which requires heat resistance and light resistance. In addition, since there are few dyes that meet the required specifications of color filters for image sensors that require heat resistance and light resistance, there are few variations in color characteristics. Moreover, even if a high concentration coloring material is added to the binder resin, the color does not become dark and the coloring power is weak. For this reason, there exists a tendency for the film thickness of a color filter to become thick. Therefore, a dyeing method or a dye dispersion method is not suitable for a color filter for a solid-state imaging device that needs to resolve a size of several microns.

  For this reason, color filters obtained by a pigment dispersion method that excels in reliability, coloring power, and color separation, such as heat resistance and light resistance, are generally used for color filters of image sensors used in line image sensors and the like. Is.

  In color scanners and color copiers, the distance between a line image sensor as a solid-state image sensor and a light source is short. This is because very strong light intensity can be obtained. In addition, as a characteristic of these devices, there is a strong demand for color reproducibility for a solid-state imaging device. As shown in FIGS. 1 and 4, the spectral characteristics of the color filter are mainly three primary colors of red, blue and green. For example, the spectral characteristics of the color filter for the image sensor mounted on the color scanner shown in FIG. 1 are compared with the spectral characteristics of the color filter for the image sensor mounted on, for example, a mobile phone as shown in FIG. Strong characteristics are required.

In addition, with the increase in density and miniaturization of line image sensors and two-dimensional image sensors, miniaturization of color filters used for these is also required. For this reason, the exposure wavelength of lithography used in the color filter manufacturing process is also shortened. In the current exposure process, for example, the use of i-line (365 nm) has become common.
JP-A-11-14825 JP 11-209631 A JP 2000-95805 A JP 2000-44822 JP-A-6-67012

  FIG. 1 shows light transmittance characteristics of a color filter desirable for a color scanner, a color copier, and the like. This can be achieved by the present invention. The green filter has low transmittance of 400 to 450 nm and 610 to 700 nm, the red filter has low transmittance of 400 to 530 nm, and the blue filter has low transmittance of 550 to 700 nm.

  In other words, the spectral characteristics are such that the main sensitivities of each color (for example, 450 nm for blue, 530 nm for green, and 620 nm for red) do not mix colors. For this reason, the transmittance at a wavelength where the spectral characteristics of blue and green and green and red cross each other is particularly low. Note that the spectral characteristics excellent in color separation as described above are not only line image sensors used in color scanners, color copiers, etc., but also media that emphasize color characteristics such as single-lens reflex digital cameras, that is, two-dimensional. This characteristic is also required for image sensors.

  By the way, the method for forming the color filter as described above is not particularly limited to the following method, but a colorant such as a pigment is dispersed in a transparent resin and absorbed by ultraviolet rays such as i-line. It is considered that a method of patterning a color resist composed of an initiator, a monomer and the like having a pattern by lithography is common.

  However, when the color filter has a deep spectral characteristic as shown in FIG. 1, the transmittance at a short wavelength used for exposure, for example, i-line (365 nm), is close to zero, so that patterning is possible. It becomes extremely difficult. Alternatively, even if the patterning can be performed, a portion in which the color resist is not sufficiently cured due to insufficient light irradiation amount occurs. For this reason, the color resist portion after patterning, that is, the occurrence of a stain that forms a spot on the color filter, uneven color unevenness or uneven film thickness occurs, for example, and if the lower part of the resist is not sufficiently cured, There is a problem in that the edge of the portion patterned in the previous process is peeled off due to the infiltration of the developer in the process.

  In particular, the green colorant has a remarkably low transmittance at a short wavelength as used in miniaturized lithography. For this reason, green has a problem that it is extremely difficult to provide a color filter with good color separation.

  For example, a color filter using a pigment as a colorant has a thickness of 1 to 2 μm on a flattened layer on the surface of a semiconductor substrate obtained by dispersing a photosensitive resin composition in which a pigment having an average particle size of submicron order is dispersed in a transparent resin. The coating is formed and formed by sequentially processing the steps consisting of pre-baking, exposure, development, and thermosetting. In this case, it is necessary to increase the pigment concentration in order to form a color filter excellent in color separation as shown in FIG. That is, when a sufficient pigment concentration cannot be obtained, it is necessary to increase the film thickness. For example, in one case, it has been found that it is necessary to increase the film thickness to about 3 μm.

  When the pigment concentration is increased, the pigment particles are likely to remain as a residue after development. There is a problem that this residue causes noise. For this reason, for example, the pigment concentration of the pigment dispersion type color filter is desirably 50% or less by weight%, and more desirably 40% or less.

  On the other hand, when the film thickness is increased, for example, when exposure is performed using a normal stepper, there is a problem that defocusing is likely to occur and resolution is deteriorated. For example, when a color filter having a width of several microns is manufactured, there is a problem that the edge shape is deteriorated. Therefore, in a normal manufacturing process, it is desirable that the film thickness of the color filter not exceed 2.5 μm, more preferably not exceed 2 μm.

  In general, red coloring agents have weak color coloring power. For this reason, for example, in order to set the transmittance in the wavelength region of 400 to 550 nm to 3% or less, when a pigment is used as the colorant, a pigment concentration of about 50% is necessary, and the film thickness at that time is about 2 μm. Thick, there were two problems, that is, generation of a residue during development and a decrease in resolution performance.

  The present invention has been made in view of such problems. The object is to provide a solid-state imaging device including a color filter having spectral characteristics with good color separation that can be patterned at a short wavelength that can be used for exposure even at high density. Another object of the present invention is to provide a color solid-state imaging device and a color filter for the imaging device that are excellent in resolution, have very little residual colorant during development, and are excellent in mass productivity.

  Specific means in the present invention will be described below. Further, the reason for adopting such means will be described.

  The color solid-state image pickup device described in the embodiment of the present invention is a color solid-state image pickup device in which at least green and red color filters are formed on a plurality of photoelectric conversion elements. The layer structure is such that one of the two layers is a color solid-state imaging device which is a common color filter layer containing a yellow colorant.

  By adopting such a configuration, it is possible to provide a color filter that has excellent resolution and mass productivity and has spectral characteristics with good color separation.

  The color solid-state imaging device described in the embodiments of the present invention is a color solid-state imaging device in which a plurality of color filters for red, green, and blue respectively corresponding to a plurality of photoelectric conversion devices are formed. The color filter is a color solid-state imaging device having a two-layer structure.

  Furthermore, in the solid-state imaging device, a color solid-state imaging device in which a yellow colorant is included in at least one of the two layers.

  The color solid-state imaging device described in the embodiments of the present invention is a color solid-state imaging device in which a plurality of color filters for red, green, and blue are respectively formed on a plurality of photoelectric conversion devices. The color filter is a color solid-state imaging device having a two-layer structure.

  Furthermore, in the solid-state imaging device, a color solid-state imaging device in which a yellow colorant is included in at least one of the two layers.

  In each of the color solid-state image sensors, the main component of the yellow colorant is C.I. Pigment Yellow 139, 150, or 185.

  The color filter described in the examples of the present invention is a green color filter having a two-layer structure, and the total spectral characteristic thereof is a transmittance of 5% or less for light having a wavelength of 400 to 450 nm, The transmittance for light with a wavelength of 620 to 670 nm is 5% or less, the wavelength of 30% transmittance is in the range of 490 nm to 520 nm on the short wavelength side, 570 to 600 nm on the long wavelength side, and the peak wavelength is 500 to 550 nm. The color filter has a transmittance of 60 to 80%.

  The color filter described in the examples of the present invention is a red color filter having a two-layer structure, and its total spectral characteristic is a transmittance of 5% or less with respect to light having a wavelength of 400 to 550 nm. The color filter has a wavelength of 50% transmittance in the range of 570 nm to 605 nm and a transmittance of 80% or more for light having a wavelength of 600 to 650 nm.

  Another color solid-state imaging device described in the embodiment of the present invention has a plurality of photoelectric conversion elements, and at least a part of the plurality of photoelectric conversion elements corresponds to the plurality of photoelectric conversion elements. Is a color solid-state imaging device in which a color filter having a two-layer structure is formed, and the color filter includes a first color filter layer composed of a plurality of band-like regions orthogonal to each other, and a first color filter layer here Has a crossing region, which is a portion where the orthogonal belt-shaped regions intersect, and a non-crossing region, which is a portion where the belt-shaped regions do not intersect, and a window section defined by the perpendicular belt-shaped regions is formed between the belt-shaped regions. A second color filter layer formed on the intersecting region, a third color filter layer formed on the non-intersecting region, and a predetermined photoelectric of the photoelectric conversion elements in the window portion. And a fourth color filter layer formed on the conversion element.

  Furthermore, the first color filter layer of the color solid-state imaging device is a color solid-state imaging device containing a yellow colorant.

  When forming a green color filter (hereinafter sometimes referred to as a green filter), if at least the transmittance of light having a wavelength of 400 to 450 nm is 5% or less, the transmittance of light at the exposure wavelength (365 nm) is 400 nm. It becomes below the transmittance | permeability in. For this reason, insufficient exposure to the color resist layer occurs, and in particular, the curing of the lower portion of the resist layer becomes insufficient. For this reason, peeling of the patterned resist is likely to occur.

  For example, in a green filter, when the transmittance at 400 nm is 5%, the transmittance at the exposure wavelength (365 nm) decreases to about 3%.

  On the other hand, the green filter is composed of several kinds of green colorants and yellow colorants, and in particular, the wavelength transmittance of 400 to 480 nm is adjusted with yellow colorants. Similarly, a red color filter (hereinafter sometimes referred to as a red filter) is composed of several red colorants and a yellow colorant, and in particular, in the 400 to 450 nm wavelength region, a yellow colorant. It is adjusted with.

  For the red filter, even if the transmittance at 400 to 450 nm is 5% or less, the transmittance at the exposure wavelength (365 nm) is rather increased due to the characteristics of the yellow and red colorants (pigments). For this reason, a sufficient amount of light for curing can be obtained even in the lower part of the resist, so that the problem of adhesion does not occur. Rather, the red colorant (pigment) has a characteristic that the transmittance increases at 400 to 420 nm. For this reason, sufficient color separation cannot be performed by itself.

  If it is formed as a single layer, the thick film becomes thick in relation to the colorant (pigment) concentration. In this case, there is a problem that a residue occurs and a problem that the resolution is lowered and the shape is deteriorated. For this reason, this problem can be solved by adopting a two-layer structure with a yellow colorant (pigment) color filter having a low transmittance at a wavelength of 400 to 480 nm. That is, a red filter excellent in color separation can be obtained.

  For example, yellow pigment C.I. I. In a color filter using Pigment Yellow 139, for example, when the transmittance at 400 nm is 2%, the transmittance in the exposure wavelength region (365 nm when using i-line) is 15%. For this reason, in the yellow color filter layer, the problem of adhesion due to insufficient transmitted light amount does not occur.

  Therefore, in the color solid-state imaging element according to the invention, a filter layer mainly composed of a yellow colorant common to a color filter mainly composed of green and red colorants is referred to as a green or red color filter layer. Separately formed. By forming two color filter layers, the transmittance of the exposure wavelength in each layer can be increased. For this reason, even if it is a color filter with a high pigment density | concentration which has the spectral characteristic which is excellent in color separation, the resolution is excellent and the color solid-state image sensor provided with the color filter for green and red without a pattern peeling can be obtained. In this specification, a yellow pigment will be described as a common colorant. However, a colorant other than yellow (pigment / dye) may be included as long as it is a common colorant, and the other green or red color may be included. Spectral characteristics can be adjusted by adding a colorant (pigment / dye) excessively contained in one of the filter layers which is not common (not common) or common to the common color filter layer.

  By the way, the main sensitivities of a color solid-state imaging device provided with color filters composed of three primary colors are around 450 nm for blue, 530 nm for green, and 620 nm for red. If color separation is poor in each color filter, color noise is generated due to transmission of unnecessary light outside the desired wavelength region, and the light sensitivity of the solid-state imaging device is relatively deteriorated. For example, regarding the relative sensitivity, in the green color filter, when the transmittance of green is 80%, if the transmittance of a blue wavelength of 450 nm is 10%, the relative sensitivity to green blue is 70%.

  The green color filter in the present invention is a green color filter having a two-layer structure so that the resolution is improved and the residue is reduced. For this purpose, the total spectral characteristics of the two-layer structure are, for example, that the transmittance at 400 to 450 nm is 5% or less, the transmittance at 620 to 670 nm is 5% or less, and the wavelength of 30% transmittance is 490 nm to 520 nm on the short wavelength side. It has been found that it is particularly desirable that the transmittance is 60 to 80% in the range of 570 to 600 nm on the long wavelength side and the peak wavelength is in the range of 500 to 550 nm.

  The transmittance in the range of 500 to 550 nm is 60 to 80%, whereas the transmittance at 450 nm which is the main sensitivity of blue and 620 nm which is the main sensitivity of red is preferably as low as 5% or less. I understood it. With this configuration, the blue and red color noises of the green color filter can be kept low.

  In addition, the red color filter in the present invention is a red color filter having a two-layer structure so as to improve the resolution and reduce the residual, like the green color filter. For this purpose, the total spectral characteristics of the two-layer structure are such that the transmittance of light having a wavelength of 400 to 550 nm is 5% or less, the wavelength of 50% transmittance is in the range of 570 nm to 605 nm, and the transmittance of 600 to 650 nm is 80. % Or more was found to be particularly desirable.

  The transmittance for light having a wavelength of 600 to 650 nm, which is the main sensitivity of red, is 80% or more, whereas the transmittance is for light of 530 nm, which is the main sensitivity of green, and 450 nm, which is the main sensitivity of blue. Was found to be 5% or less. With this configuration, the green and blue color noises of the red color filter can be kept low.

  According to the present invention, a color filter having a sufficient colorant concentration so as to have spectral characteristics excellent in color separation, the color resist pattern in the exposure process has excellent resolution, color noise is suppressed, and the resist is cured. In addition, it is possible to obtain a color solid-state imaging device including a color filter which can supply a sufficient amount of light necessary for preventing the color resist pattern from being peeled off and generating stains and unevenness.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same symbols are assigned to the same elements.

  2 and 3 show a color solid-state imaging device according to the first embodiment of the present invention. FIG. 1 is a diagram showing the spectral characteristics of a color filter according to the present invention. FIG. 4 is shown for comparison with the spectral characteristics of the color filter according to the present invention, and shows an example of the spectral characteristics of a conventional color filter formed so as to be particularly excellent in sensitivity.

  FIG. 1 is a diagram showing the spectral characteristics of a color filter according to the present invention which is particularly configured to have excellent color separation. 1, 2 and 3 represent the spectral characteristics of the color filters for red, green and blue, respectively. The horizontal axis indicates the wavelength (nm), and the vertical axis indicates the transmittance for each color wavelength.

  FIG. 2 is a plan view of the color filter 10 of the color solid-state imaging device 14 according to the first embodiment of the present invention. In the color filter 10, the color filters 11, 12, and 13 for three colors of red (R), green (G), and blue (B) are arranged in a stripe pattern by a so-called linear arrangement. The arrangement of the color filter of the present invention is not limited to such a linear arrangement.

  FIG. 3 is a cross-sectional view of the color solid-state imaging device 14 according to the first embodiment of the present invention, and corresponds to the A-A 'portion of FIG.

  As shown in FIG. 4, the conventional color filter in which light sensitivity is important is compared with the case of the present invention in FIG. 1, the spectral characteristic 4 of the red color filter, the spectral characteristic 5 of the green color filter, and the blue color filter. Both of the spectral characteristics 6 of the color filter for use have high transmittance at wavelengths of main sensitivity (450 nm, 530 nm, and 620 nm) in each color. However, the transmittance at wavelengths (500 nm and 580 nm) where the spectral characteristics cross each other is high, and color separation is not sufficient for use in, for example, a color scanner or a color copier.

  The color solid-state imaging device 14 according to the first embodiment of the present invention is configured so that the unevenness of the light receiving portion is buried on the substrate 16 on which the plurality of photoelectric conversion elements 15 as the light receiving portions are formed, as shown in a cross section in FIG. The first flattening layer 17, the color filter 10 for color-separating incident light, and the second flattening layer 18 are sequentially formed. A part of the color filter 10 has a two-layer structure.

  In the case where the dimension of the light receiving surface of the photoelectric conversion element 15 is as small as several μm and sufficient photosensitivity is difficult to obtain, a microlens (not shown in FIG. 10) is formed on the second planarization layer 18. d) can also be formed.

  The green filter 12 shown in FIG. 2 is formed by overlapping a yellow color filter layer 21 formed as a first layer and a green color filter layer 22 formed as a second layer, as shown in the cross-sectional view of FIG. Is done. The yellow color filter layer 21 is a layer containing at least a yellow colorant. As the colorant, pigments or dyes or intermediates thereof can be used.

  The green color filter layer 22 is a layer containing at least a green colorant. Examples of the green pigment include, but are not limited to, C.I. I. Pigment Green 7, 36, and 37 can be used. Examples of the green dye include, but are not limited to, C.I. I. Acid green 25, 41 can be used. The spectral characteristic of the green filter 12 is shown as 2 in FIG.

  FIG. 5 shows a spectral characteristic 31 of the yellow color filter layer 21, a spectral characteristic 32 of the green color filter layer 22, and a spectral characteristic 33 of the green filter 12 formed by superimposing the yellow color filter layer 21 and the green color filter layer 22. Indicates.

  Similarly, as shown in the cross-sectional view of FIG. 3, the red filter 11 shown in FIG. 2 is formed by superposing the yellow color filter layer 23 formed as the first layer and the red color filter layer 24 formed as the second layer. It is formed. The yellow color filter layer 23 is a layer containing at least a yellow colorant. The red color filter layer 24 is a layer containing at least a red colorant. Examples of red pigments include, but are not limited to, C.I. I. Any of CI Pigment Red 123, 155, 168, 177, 180, 217, 220 can be used. Examples of red dyes include, but are not limited to, C.I. I. Any of Acid Red 37, 50, 111, 114, 257, and 266 can be used. The spectral characteristic of the red filter 11 is shown as 1 in FIG.

  FIG. 5 shows the spectral characteristics 34 of the red color filter layer 24 and the spectral characteristics 35 of the red filter 11 formed by superimposing the yellow color filter layer 23 and the red color filter layer 24.

  In the first embodiment, the yellow color filter layers 21 and 23 are formed by the same process. For this reason, colorants of the same type and concentration can be included. The spectral characteristics of FIG. 5 are obtained when the yellow color filter layers 21 and 23 are formed by the same process. Although it is desirable to manufacture by the same process, the yellow color filter layers 21 and 23 can be sequentially formed in separate processes when the concentration of the colorant is different.

  The blue filter 13 shown in FIG. 2 is formed by only one blue color filter layer 25 as shown in the cross-sectional view of FIG. The blue color filter layer 25 is a layer containing at least a blue colorant. Examples of the blue pigment include, but are not limited to, C.I. I. Any of CI Pigment Blue 15, 15: 3, 15: 4, 15: 6, 6, 22, and 60 can be used. Examples of the blue dye include, but are not limited to, C.I. I. Any of Acid Blue 41, 83, 90, 113, and 129 can be used. The spectral characteristic of the blue filter 13 is shown as 3 in FIG.

  Each color filter layer 21, 22, 23, 24, 25 is a surface of a substrate 16 on which a photoelectric conversion element 15 is formed from a photosensitive resin composition in which a pigment having an average particle size of submicron order is dispersed in a transparent resin. The first planarizing layer 17 is formed by processing each process including coating, pre-baking, exposure, development, and thermosetting. For example, the yellow color filter layer 21 (and 23), the green color filter layer 22, the red color filter layer 24, and the blue color filter layer 25 are repeated in the same number of times corresponding to the number of colors. The structure shown in 3 is obtained.

  When the color solid-state imaging device 14 is used in, for example, a color copying machine, it is desirable to use a pigment dispersion method that is particularly excellent in heat resistance and light resistance as a coloring method of the color filter layers 21 to 25 in the present invention. However, the present invention is not limited to the pigment dispersion method. Depending on the application, for example, a so-called dyeing method in which a transparent resin such as PVA or casein is patterned and a dye is fixed to the transparent pattern to form a color filter may be used. In addition, a dye having at least one polymerizable functional group in the molecule is used as a monomer as it is or as a dyed polymer by polymerization, and a photosensitive agent (photoinitiator, etc.) is mixed to form a color resist. It is also possible to use a so-called dye dispersion method in which a resist is patterned by lithography to form a color filter.

  Examples of the dye having at least one polymerizable functional group in the molecule include anthraquinone dyes, nitroso dyes, nitro dyes, azo dyes (that is, monoazo dyes, diazo dyes, triazo dyes, polyazo dyes). Dyes, azoic dyes, stilbene dyes, carotenoid dyes, diphenylmethane dyes, triallylmethane dyes, xanthene dyes, acridine dyes, quinoline dyes, methine dyes, polymethine dyes, thiazole dyes , Indamine dyes, indophenol dyes, azine dyes, oxazine dyes, thiazine dyes, sulfur dyes, lactone dyes, amino ketone dyes, hydroxy ketone dyes, indigoid dyes, phthalocyanine dyes, natural organic dyes Products, oxides, inorganic pigments, etc. Yibin selected and can be used. A dye having no polymerizable functional group can be used after introducing a functional group.

  In the color solid-state imaging device 14 of the present invention, for example, as shown in the cross-sectional view of FIG. 3, the green filter 12 includes a yellow color filter layer 21 formed as a first layer and a green color filter layer formed as a second layer. It is formed by superposition of 22 pieces. Therefore, as shown in FIG. 1, the transmittance curve 2 of the green color filter intersects the transmittance curve 1 of the red color filter and the transmittance curve 3 of the blue color filter layer with low transmittance. Even when it is formed so as to have spectral characteristics excellent in color separation, the color filter layer is peeled off, the stain caused by the developer soaking into the bottom of the color resist pattern, and pattern deformation partially occur In addition, unevenness, which is an appearance defect observed when the pixel shape changes partially, does not occur.

  Further, by suppressing the transmittance of the green color filter layer 22 from 620 to 670 nm to be low, color separation from red having a main sensitivity at 620 nm increases, and color noise can be reduced.

  Also, C.I. having absorption at 400 to 450 nm. I. The yellow color filter 23 having Pigment Yellow 139 as the main pigment is formed as the first layer, and the red color filter layer 24 is formed thereon to form the red filter 11, so that the transmittance of the red filter 11 at 400 to 450 nm is increased. Since it can be suppressed more than the conventional red color filter (see FIG. 4), a color filter excellent in color separation can be obtained.

  A method for manufacturing the color solid-state imaging device 14 according to the first embodiment will be described below. A first planarization layer 17 is formed on a substrate 16 on which a plurality of photoelectric conversion elements 15 as shown in FIG.

  As the first planarizing layer 17, for example, a thermosetting acrylic resin can be used. An acrylic resin is applied and formed on the surface of the substrate 16 with a thickness of about 1 μm by spin coating, and is heated on a hot plate at 180 ° C. for about 10 minutes to be thermally cured.

  Next, yellow color filter layers 21 and 23 are formed on the first planarization layer 17. In order to form the yellow color filter layers 21 and 23, for example, C.I. I. Pigment Yellow 139 can be used. In this embodiment, C.I. I. A color resist layer containing a yellow pigment whose main pigment is Pigment Yellow 139 is applied and formed in a thickness of about 0.7 μm by spin coating. Subsequently, for example, temporary drying is performed for about 1 minute on a hot plate at 80 ° C.

  The yellow pigment is not limited to these examples. I. Pigment Yellow 139, C.I. I. Pigment yellow 150 and C.I. I. Pigment Yellow 185 or the like can be used alone or in combination. FIG. 6 shows the transmittance of the yellow filter layer using C.I. Pigment Yellow 139, 150, and 185 with respect to wavelength. 37 is C.I. I. Pigment Yellow 139 and 38 are C.I. I. Pigment Yellow 150 and 39 are C.I. I. This is a spectral characteristic when Pigment Yellow 185 is used alone. Examples of yellow dyes include, but are not limited to, C.I. I. Acid yellow 17, 49, 67, 72, 127, 110, etc. can be used.

After temporary drying, the yellow color filter layers 21 and 23 are patterned by a photolithographic method. For pattern formation, for example, an i-line stepper manufactured by Nikon Corporation can be used. For example, i-line is irradiated at an exposure amount of 300 mJ / cm ² through a mask having a light transmission region corresponding to the shape of the resist pattern.

  An i-line stepper is generally used as an exposure machine, but an aligner that irradiates light including far ultraviolet rays can be used. For example, a g-line (405 nm) stepper can also be used.

  Next, for example, spray development is performed for 1 minute with a developer of an organic alkaline aqueous solution mainly containing TMAH (tetramethylammonium hydroxide), and then rinse with pure water and spin drying are performed.

  Next, the yellow color filter layers 21 and 23 can be formed by heating for about 10 minutes on a hot plate at 180 ° C. and thermosetting the patterned color resist layer.

  In this embodiment, the yellow color filter layers 21 and 23 are finally selectively formed on the photoelectric conversion elements 15 (G) and 15 (R) whose main sensitivities are green and red. The film thickness of the yellow color filter layers 21 and 23 in the present embodiment can be set to 0.7 μm, for example.

  Next, a resist layer for the green color filter layer 22 containing a green colorant as a main coloring material is formed by the same process as the yellow color filter layers 21 and 23. Similar to the yellow color filter layer, it is patterned by photolithography.

The green color filter layer 22 is selectively formed on the yellow color filter layer 21 previously formed on the photoelectric conversion element 15 (G) whose main sensitivity is finally green. The exposure amount at this time is 1000 mJ / cm ² , and the film thickness of the green color filter layer 22 can be 1.8 μm.

Next, a resist layer for the red color filter layer 24 is formed by a photolithographic method using a red color resist containing a red colorant as a main coloring material in the same manner as the yellow and green color filter layers 21, 23, and 22. Form. The red color filter layer 24 is selectively formed on the yellow color filter layer 23 previously formed on the photoelectric conversion element 15 (R) having red as the main sensitivity. The exposure amount at this time is 400 mJ / cm ² , and the film thickness of the red color filter layer 24 can be 1.5 μm.

Next, a blue color filter layer 25 containing a blue colorant as a main coloring material is formed by a photolithographic method in the same manner as the yellow, green, and red color filter layers 21, 23, 22, and 24. The blue color filter layer 25 is selectively formed on the first flattening layer on the photoelectric conversion element 15 (B) finally having blue as the main sensitivity. The exposure amount at this time is 900 mJ / cm ² , and the film thickness of the blue color filter layer 25 can be 2 μm.

  Finally, a second planarization layer 18 is formed in the same manner as the first planarization layer 17 for planarizing the surface of the color filter 10. A thermosetting acrylic resin is applied and formed on the surfaces of the green, blue and red color filter layers 22, 25 and 24 with a film thickness of 1 μm. Then, it heats for about 10 minutes on a 180 degreeC hotplate, and is hardened.

  The line width of the color filter shown in FIG. 2 formed in this way can be set to 10 μm, for example, for all of green, red, and blue.

  Through the above steps, peeling of the bottom of the filter layer can be prevented, and occurrence of spots and unevenness in the filter layer can be prevented. Further, it is possible to prevent a residue from being generated after development by the photolithographic method. For this reason, a sharp and well-shaped color filter was obtained.

  The spectral characteristics of the green filter 12 composed of the yellow color filter layer 21 and the green color filter layer 22 are as shown in the transmittance curve 2 of FIG. 1, and the transmittance is 2% or less at wavelengths of 400 to 450 nm and 620 to 680 nm. The peak transmittance near 530 nm was 68%, and the spectral characteristics excellent in color separation were obtained.

  Further, in the green filter 12, the total spectral characteristic is a transmittance of 5% or less with respect to light having a wavelength of 400 to 450 nm by adjusting the film thicknesses of the yellow and green color filter layers 21 and 22 and the colorants of the respective layers. The transmittance for light having a wavelength of 620 to 670 nm is 5% or less, the wavelength of 30% transmittance is in the range of 490 nm to 520 nm on the short wavelength side, 570 to 600 nm on the long wavelength side, and the peak wavelength is 500 It was found that the transmittance was in the range of ˜550 nm and the transmittance could be adjusted to be 60 to 80%. Such spectral characteristics are suitable as a green color filter for a solid-state imaging device used in a color scanner or a color copier.

  Further, the spectral characteristics of the red filter 11 composed of the yellow color filter layer 23 and the red color filter layer 23 are as follows. As shown in the transmittance curve 1 of FIG. 1, the transmittance is 1% or less in a wavelength range of 400 to 550 nm. The transmittance at a wavelength of 620 nm was 90%, and a spectral characteristic excellent in color separation was obtained.

  Further, with respect to the red filter 11, by adjusting the film thickness of the yellow and red color filter layers 23 and 24 and the kind and concentration of the colorant of each of the above layers, the total spectral characteristic has a transmittance with respect to light having a wavelength of 400 to 550 nm. It was found that the wavelength of 5% or less, the wavelength of 50% transmittance is in the range of 570 nm to 605 nm, and the transmittance for light having a wavelength of 600 to 650 nm can be adjusted to 80% or more. A color filter having such spectral characteristics is suitable as a color filter for red used in, for example, a solid-state imaging device used in a color scanner or a color copier.

  An example in which the first embodiment according to the present invention is compared with other similar color filter forming methods will be described below.

<Comparative Example 1>
In Comparative Example 1, an attempt was made to obtain the same spectral characteristics as in the first embodiment of the present invention using only a single color filter instead of employing a two-layer color filter as in the present invention. This is the case.

The steps up to the step of forming the first planarizing layer are the same as in the first embodiment. In order to form a green color filter on the first planarizing layer, a green color obtained by mixing the yellow pigment contained in the yellow color filter layer of the first embodiment of the present invention and the green pigment contained in the green color filter layer is mixed. A color resist was applied and formed in a thickness of about 2.5 μm by spin coating. Subsequently, after temporary drying on a hot plate at 80 ° C. for 1 minute, an exposure dose of 2000 mJ / cm ² was irradiated through the same mask as in the first embodiment using a Nikon i-line stepper. did.

  Subsequently, spray development was performed for 1 minute with a developer of an organic alkali aqueous solution containing TMAH as a main component, followed by rinsing with pure water and spin drying.

In the case of this comparative example, most of the green filter after development was peeled off from the first planarization layer by development. When the thickness of the color resist layer is as thick as 2.5 μm, it is considered that curing is insufficient even by irradiation with an exposure amount of 2000 mJ / cm ² .

<Comparative example 2>
The exposure amount of Comparative Example 1 was increased to the limit of a normal stepper device of 2000 mJ / cm ² or more and irradiated, and the green filter after development was observed. The green filter was only partially formed, most of which Was peeling. It is considered that a portion that is not sufficiently cured is generated even by irradiation with an exposure amount exceeding 2000 mJ / cm ² .

<Comparative Example 3>
The development time of Comparative Example 1 was shortened from 1 minute to 30 seconds in Comparative Example 1, and the green filter after development was observed. Although the green filter was patterned, the residue was so large that the flattened layer was visually observable, and a stain was generated on the bottom of the edge of the green filter. This is probably because the green color resist is not sufficiently removed because the development time is short.

  FIG. 7 shows a pattern of each layer and a manufacturing procedure of the color filter 41 according to the second embodiment of the present invention formed on the surface of the substrate 40 including the photoelectric conversion element, and a cross section of the color solid-state image sensor 14.

  As shown in FIG. 7A, a yellow color filter layer 43 including a plurality of band-like regions 42 orthogonal to each other is first formed on a substrate 40. The formation and patterning of the resist layer can be performed by the same method as in the first embodiment. Since the plurality of belt-like regions 42 are orthogonal to each other, each belt-like region 42 is formed by a plurality of quadrangular intersections 44 and a plurality of quadrangular non-intersections 45. In addition, a rectangular window 46 that is a through hole for the yellow color filter layer 43 partitioned by the band-like region is formed between the band-like regions.

  In this embodiment, the intersection 44 is located on a red photoelectric conversion element (not shown), the non-intersection 45 is located on a green photoelectric conversion element (not shown), and the window 46 is blue. Corresponds to the position of the photoelectric conversion element (not shown). The present invention is not limited to such a combination.

  Next, as shown in FIG. 7B, a rectangular green color filter layer 47 having the same shape as the non-intersecting portion is formed on the non-intersecting portion 45. The formation and patterning of the resist layer can be performed by the same method as in the first embodiment.

  Next, as shown in FIG. 7C, a square red color filter layer 48 having the same shape as the intersection is formed on the intersection 44. The formation and patterning of the resist layer can be performed by the same method as in the first embodiment.

  Next, as shown in FIG. 7D, a rectangular blue color filter layer 49 having the same shape as the window is formed on the substrate 40 exposed by the window 46. Formation and patterning of the filter film can be performed by the same method as in the first embodiment.

  In this way, a green color filter having a two-layer configuration of a yellow color filter layer 43 and a green color filter layer 47, a red color filter having a two-layer configuration of a yellow color filter layer 43 and a red color filter layer 48, and The color solid-state imaging device 14 having the color filter 41 having the blue color filter composed of the single blue color filter layer 49 can be formed. In the second embodiment, the ratio of the green color filter, red color filter, and blue color filter is 2: 1: 1.

  FIG. 7E is a cross-sectional view of the color solid-state imaging device according to the second embodiment. This corresponds to the A-A ′ portion of FIG.

  FIG. 8 shows a pattern of each layer of the color filter 41 formed on the surface of the substrate 40 including the photoelectric conversion element, a manufacturing procedure, and a cross-sectional view of the color solid-state imaging element.

  As shown in FIG. 8A, first, a yellow color filter layer 43 composed of a plurality of substantially band-like regions 50 orthogonal to each other is formed on the substrate 40. Formation and patterning of the filter film can be performed by the same method as in the first embodiment. In FIG. 8, the substantially band-like region 50 is formed so as to be orthogonal to each other in the vertical direction and the horizontal direction. For this reason, the substantially band-like region 50 is formed by a plurality of substantially square intersections 51 and a plurality of substantially square non-intersections 52. In addition, a first window portion 53 that is a rectangular through hole with rounded four corners defined by the belt-like region is formed between the substantially belt-like portions.

  The intersection 51 is located on a red photoelectric conversion element (not shown), the non-intersection 52 is located on a green photoelectric conversion element (not shown), and the first window 53 is blue photoelectric conversion. This corresponds to the position of an element (not shown).

  Next, as shown in FIG. 8B, a green color filter layer 54 corresponding to the shape of the substantially band-like region 50 is formed. In this case, the intersecting portion 51 is formed with a second window portion 55 that is a rectangular through hole with rounded corners. Formation and patterning of the filter film can be performed by the same method as in the first embodiment.

  Next, as shown in FIG. 8C, a quadrilateral red color filter layer 56 is formed by rounding the four corners of the shape filling the second window portion 55. The formation and patterning of the resist layer can be performed by the same method as in the first embodiment.

  Next, as shown in FIG. 8D, a rectangular blue color filter layer 57 having the same shape as the first window portion is formed on the substrate 40 exposed by the first window portion 53. The formation and patterning of the resist layer can be performed by the same method as in the first embodiment.

  In this way, a green filter having a two-layer structure of a yellow color filter layer 43 and a green color filter layer 54, a red filter having a two-layer structure of a yellow color filter layer 43 and a red color filter layer 56, and a single blue layer The color solid-state imaging device 14 having the color filter 41 having the blue filter made of the color filter layer 57 can be formed.

  FIG. 8E shows a cross-sectional view of the color solid-state imaging device according to the third embodiment. This corresponds to the A-A ′ portion of FIG.

  The four corners of the first and second window portions 53 and 55 are rounded. For this reason, the shapes of the red color filter layer 56 and the blue color filter layer 57 to be formed later are appropriately formed. In addition, it does not swell at the four corners and is difficult to peel off.

  FIG. 9 is a cross-sectional view of the pattern and manufacturing procedure of each layer of the color filter 41 according to the fourth embodiment of the present invention formed on the surface of the substrate 40 including the photoelectric conversion element (not shown), and the color solid-state imaging device. Indicates.

  As shown in FIG. 9A, first, a yellow color filter layer 43 including a plurality of substantially band-like regions 50 orthogonal to each other is formed on the substrate 40. Similar to the third embodiment, the substantially band-like region 50 is formed so as to be orthogonal to each other in the vertical and horizontal directions in FIG. For this reason, the substantially band-like region 50 is formed by a plurality of substantially square intersections 51 and a plurality of substantially square non-intersections 52. In addition, a first window portion 53 that is a rectangular through hole with rounded four corners defined by the belt-like region is formed between the substantially belt-like portions.

  The intersection 51 is located on a red photoelectric conversion element (not shown), the non-intersection 52 is located on a green photoelectric conversion element (not shown), and the first window 53 is blue photoelectric conversion. This corresponds to the position of an element (not shown).

  Next, as shown in FIG. 9B, a rectangular green color filter layer 60 having four rounded corners is formed on the non-intersecting portion 52. For this reason, the second window 61, which is a through hole having small radially extending portions 62 at the four corners, is formed in the intersecting portion 51.

  Next, as shown in FIG. 9C, a square red color filter layer 63 having four rounded corners is formed in the second window portion 61.

  Next, as shown in FIG. 9D, a rectangular blue color filter layer 64 having the same shape as the first window is formed on the substrate 40 exposed by the first window 53.

  In this way, a green filter having a two-layer structure of a yellow color filter layer 43 and a green color filter layer 60, a red filter having a two-layer structure of a yellow color filter layer 43 and a red color filter layer 63, and a single blue layer The color solid-state imaging device 14 having the color filter 41 having the blue filter made of the color filter layer 64 can be formed.

  9E to 9G are sectional views of the color solid-state imaging device 14 according to the fourth embodiment. FIG. 9E corresponds to the A-A ′ portion in FIG. 9D, FIG. 9F corresponds to the B-B ′ portion, and FIG. 9G corresponds to the C-C ′ portion.

  The green color filter layer 60, the red color filter layer 63, and the blue color filter layer 64 to be formed later are formed so that the four corners are rounded. For this reason, these shapes are formed appropriately. In addition, it does not swell at the four corners and is difficult to peel off.

  FIG. 10 shows a fifth embodiment in which a plurality of microlenses 78 for condensing incident light on each photoelectric conversion element 79 are provided on the color filter 73. Also in the fifth embodiment, for example, as described in the second to fourth embodiments, a color filter including two layers and one layer is formed corresponding to each of the plurality of photoelectric conversion elements.

  As shown in FIG. 10D, for example, the color solid-state imaging device according to the fifth embodiment has a color filter layer 70 composed of a single layer on a substrate 40 on which a photoelectric conversion device 79 is formed, and A color filter 73 having two layers of a lower layer 71 and an upper layer 72 can be formed. A plurality of microlenses 78 are arranged at positions corresponding to the respective photoelectric conversion elements 79. Although not limited to this method, a method for forming a microlens 78 as shown in FIG.

  As shown in FIG. 10A, first, a transparent resin layer 75 having a film thickness of about 1.1 μm is formed on the color filter 73 by using, for example, an acrylic resin coating solution. Next, as shown in FIG. 10B, for example, a lens matrix material 76 made of, for example, a phenol resin having alkali solubility, photosensitivity, and heat flow property is formed on the transparent resin layer 75 to a thickness of 0.6 μm. Apply.

  Next, using a known photolithography process, the lens matrix material 76 is patterned, leaving a region that becomes the lens matrix 77. A lens matrix 77 as shown in FIG. 10C is made of a phenol resin in the above-described region, and is formed into a round and hemispherical shape by flowing the lens matrix material 76 remaining after patterning by heat treatment at 200 ° C. It is. The lens matrix 77 can be formed as a smooth hemispherical lens matrix having a gap between the lens matrices of, for example, 0.24 μm, with a substantially appropriate flow amount of 0.1 μm on one side.

  Next, using a mixed gas of chlorofluorocarbon gases CF4 and C4F8 in a dry etching apparatus, the lens matrix 77 is used as a mask, the previously formed transparent resin layer 75 is subjected to a transfer process, and a transfer lens. That is, the microlens 78 is formed. When the lens matrix 77 and the transparent resin layer 75 are uniformly etched from above, the etching proceeds downward while maintaining the shape of the lens matrix 77, so that the shape of the transparent resin layer 75 is the same as that of the lens matrix 77. Can be etched. The height of the micro lens 78 is. For example, 1 μm. The gap between the microlenses 78 can be processed into a narrow gap of 0.04 μm, for example.

  In the transfer using the lens matrix 77, even if the etched portion reaches the surface of the lower color filter 73, the transparent resin layer 75 is dry-etched, and a part of the color filter 73 is part of the microlens. If it can be used as a part, the distance between the microlens 78 and the photoelectric conversion element 79 becomes shorter, so that the aperture ratio increases and a wide range of light can be taken in.

  As shown in FIG. 10, when the upper color filter layer 72 is formed to be smaller than the lower color filter layer 71, an extension line (L in FIG. 10D) of the upper surface of the color filter layer is formed. Even if etching is advanced beyond this, the lower end portion 80 of the microlens 78 digs through the transparent resin layer 75 instead of the color filter layer.

  The color filter layer is easily roughened by dry etching, and the etching rate is low and etching is difficult to proceed. However, the acrylic resin layer 75 does not have such a problem. Therefore, even when the lower end portion 80 of the microlens 78 enters between the color filter layers, the surface of the microlens 78 is formed smoothly and can be etched deeply, so that a large microlens can be formed. it can.

  As described above, according to the present invention, a color solid-state imaging device having a color filter for green and red, which is excellent in mass separation and excellent in color separation and resolution, and has no pattern peeling or residue, and its color filter are provided. it can.

  Although the principle of the present invention has been described above by specific embodiments, it is obvious that the above description is merely an example and does not limit the technical scope of the present invention. A person skilled in the art can freely change the contents described in the above embodiments within the scope of the present invention.

It is a figure which shows the spectral characteristic of the color filter in this invention. 1 is a plan view of a color filter 10 included in a color solid-state imaging device 14 according to a first embodiment of the present invention. It is sectional drawing of the color solid-state image sensor 14 by the 1st Example of this invention. It is a figure which shows an example of the spectral characteristic of the conventional color filter formed so that a sensitivity might be especially excellent. Spectral characteristics 31 (yellow), 32 (green), 34 (red) of a yellow color filter layer 21, a green color filter layer 22, a red color filter layer 24, and a red and green color filter having a two-layer structure in which these layers are superposed. It is a figure which shows 33 (two layers of green and yellow) and 35 (two layers of red and yellow). It is a figure which shows the transmittance | permeability with respect to the wavelength of the yellow filter layer using C.I. pigment yellow 139, 150 and 185 which is a yellow pigment. It is a figure which shows the cross-section of the pattern manufacturing procedure and color solid-state image sensor of each layer of the color filter which concerns on 2nd Example of this invention. It is a figure which shows the cross-sectional view of the pattern manufacture procedure of each layer of the color filter which concerns on the 3rd Example of this invention, and a color solid-state image sensor. It is a figure which shows the cross-sectional view of the pattern manufacturing procedure and color solid-state image sensor of each layer of the color filter which concerns on the 4th Example of this invention. It is a figure shown about the structure and manufacturing process of the color solid-state image sensor which concerns on the 5th Example which provided the micro lens on the color filter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transmittance curve of color filter for red, 2 ... Transmittance curve of color filter for green, 3 ... Transmittance curve of color filter for blue, 4 ... Transmittance curve of color filter for red, 5 ... Color filter for green 6. Transmission curve of blue color filter, 10. Color filter, 10 ... Color filter, 11 ... Red filter, 12 ... Green filter, 13 ... Blue filter, 14 ... Color solid-state imaging device, 15 ... Photoelectric conversion device, 16 DESCRIPTION OF SYMBOLS ... Substrate, 17 ... First flattening layer, 18 ... Second flattening layer, 21 ... Yellow color filter layer, 22 ... Green color filter layer, 23 ... Yellow color filter layer, 24 ... Red color filter layer, 25 ... Blue color filter layer, 31 ... Spectral characteristic, 32 ... Spectral characteristic, 33 ... Spectral characteristic, 34 ... Spectral characteristics, 35 ... Spectral characteristics, 40 ... Substrate, 41 ... Color filter, 42 ... Striped region, 43 ... Yellow color filter layer, 44 ... Crossing part, 45 ... Non-crossing part, 46 ... Window part, 47 ... Green color filter 48, a red color filter layer, 49 ... a blue color filter layer, 51 ... an intersection, 52 ... a non-intersection, 53 ... a first window, 54 ... a green color filter layer, 55 ... a second window, 56 ... red color filter layer, 57 ... color filter layer, 60 ... green color filter layer, 61 ... second window part, 62 ... expansion part, 63 ... red color filter layer, 64 ... blue color filter layer, 70 ... 1 Color filter composed of layers, 71 ... lower color filter layer, 72 ... upper color filter layer, 73 ... color fill 75 ... Transparent acrylic resin layer, 76 ... Lens matrix material, 78 ... Microlens, 79 ... Photoelectric conversion element 80 ... Lower end of microlens

Claims (10)

In a color solid-state imaging device in which color filters for at least green and red are formed on a plurality of photoelectric conversion devices,
Each of the color filters for green and red has a two-layer structure,
One of the two layers is a color solid-state imaging device in which one layer is a common color filter layer containing a yellow colorant. In a color solid-state imaging device in which a plurality of corresponding color filters for red, green, and blue are respectively formed on a plurality of photoelectric conversion devices,
A color solid-state imaging device, wherein the red color filter has a two-layer structure.   The color solid-state imaging device according to claim 2, wherein a yellow colorant is contained in at least one of the two layers. In a color solid-state imaging device in which a plurality of corresponding color filters for red, green, and blue are formed on a plurality of photoelectric conversion devices,
A color solid-state imaging device in which the green color filter has a two-layer structure.   The color solid-state imaging device according to claim 4, wherein a yellow colorant is contained in at least one of the two layers.   The main component in the yellow colorant is C.I. I. The color solid-state imaging device according to claim 1, wherein the color solid-state imaging device is any one of CI Pigment Yellow 139, 150, and 185. It is a color filter for green consisting of two layers, and the total spectral characteristics are
The transmittance for light having a wavelength of 400 to 450 nm is 5% or less, the transmittance for light having a wavelength of 620 to 670 nm is 5% or less,
Color with a 30% transmittance wavelength in the range of 490 nm to 520 nm on the short wavelength side, 570 to 600 nm on the long wavelength side, and a peak wavelength in the range of 500 to 550 nm, with a transmittance of 60 to 80% filter. It is a red color filter consisting of two layers, and the total spectral characteristics are
The transmittance is 5% or less for light having a wavelength of 400 to 550 nm,
A color filter having a wavelength of 50% transmittance in the range of 570 nm to 605 nm and a transmittance of 80% or more for light having a wavelength of 600 to 650 nm. A color solid-state imaging device having a plurality of photoelectric conversion elements, and corresponding to the plurality of photoelectric conversion elements, wherein a color filter having at least a part of a two-layer structure is formed on the plurality of photoelectric conversion elements. ,
The color filter is
A first color filter layer composed of a plurality of belt-shaped regions orthogonal to each other, and wherein the first color filter layer includes a non-intersecting region that is a portion that does not intersect with a crossing region that is a portion where the orthogonal belt-shaped regions intersect And a window section defined by orthogonal belt-like regions is formed between the belt-like regions,
A second color filter layer formed on the intersection region;
A third color filter layer formed on the non-intersecting region;
A color solid-state imaging device having a fourth color filter layer formed on a predetermined photoelectric conversion device among the photoelectric conversion devices in the window portion.   10. The color solid-state imaging device according to claim 9, wherein the first color filter layer includes a yellow colorant.

Images