JP2010272654A - Solid-state image pickup device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image pickup device for obtaining high sensitivity, even if the pixel size becomes microscopic; and the manufacturing method thereof. <P>SOLUTION: There is provided the solid-state image pickup device equipped with a plurality of pixels arranged in a matrix. Each of the plurality of pixels includes a light receiving section that converts light to an electrical signal. The image pick-up device includes a color filter consisting of first and second color filter sections formed at the upper part of the light receiving section, which corresponds to each pixel. The first color filter section is formed in the center of the color filter in a surface direction of the pixel, and the second color filter section is formed in the peripheral part in the surface direction of the pixel having almost the same spectral characteristics as those of the first color filter. The refractive index of the first color filter section is higher than that of the second color filter section. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and a method for manufacturing the same, and more particularly to a solid-state imaging device in which a plurality of pixels are arranged and a light receiving unit that converts incident light into an electrical signal for each pixel and a manufacturing method thereof.

  In recent years, with the reduction in the chip size of the solid-state imaging device and the increase in the number of pixels, the digital still camera, the digital movie camera, the camera-equipped mobile phone, and the like have been reduced in size and performance. In the solid-state imaging device, the number of pixels has been increased to increase the resolution of the camera, and the size of the chip has been reduced with the miniaturization of the camera optical system.

  On the other hand, despite the fact that the pixel size is becoming smaller, there is a market demand for imaging with high sensitivity even at low illuminance. Therefore, various microlens structures have been proposed in order to increase the light collection effect on the light receiving portion in the pixel.

  However, as the pixel size becomes finer, the light condensing effect of the microlens structure becomes insufficient. That is, when the pixel size is reduced, the distance from the light receiving unit to the microlens is relatively increased, and the light collected by the microlens becomes difficult to be collected by the light receiving unit. Even if the light can be condensed on the light receiving unit, if the F-number of the camera lens is small, the sensitivity is reduced with respect to the oblique incident light. Here, the F value represents the brightness of the lens, and can be obtained by dividing the focal length by the effective aperture. The F value indicates that the smaller the number, the brighter the light from the oblique light is incident.

  A solid-state imaging device generally has a color filter, and the color filter is generally formed by patterning a photosensitive resin containing a dye by photolithography. Here, the color filter is a filter that allows light in a specific wavelength region in visible light to pass therethrough. In general, pigment-based color materials are often used as color materials for color filters. Here, the pigment is used as a coloring material to be colored, and is an opaque pigment that is insoluble in water, fats and oils, alcohol, organic chemicals, and the like in a fine powder form. However, if the pixel size is further reduced, light scattering due to pigment particles is unavoidable, and the sensitivity variation for each pixel increases and the image quality is impaired. As a countermeasure, it has been proposed to use a dye for the color material of the color filter. However, there is a problem that the dye oozes out to surrounding pixels when heated or immersed in a solvent. Here, the dye is used as a coloring material to be colored and can be dissolved in water, oils and fats. A conventional solid-state imaging device using a photosensitive dye material will be described below.

  FIG. 12 is a cross-sectional view of a conventional solid-state imaging device. A solid-state imaging device 800 illustrated in FIG. 12 includes a semiconductor substrate 811, a light receiving unit 812, a transfer electrode 813, a planarization film 814, color filters 815G and 815R, a microlens lower planarization layer 817, and a microlens 818. With. As shown in FIG. 12, in the solid-state imaging device 800, a plurality of light receiving portions 812 are formed on a semiconductor substrate 811, and a transfer electrode 813 is formed on the semiconductor substrate 811 between the plurality of light receiving portions 812. Further, a planarization film 814 is formed on the semiconductor substrate 811 so as to fill the convex portion formed by the transfer electrode 813, and the planarization film 814 is made of a resin containing a pasted pigment. Color filters 815R and 815G are formed. Further, a microlens lower planarization layer 817 is formed on the color filters 815R and 815G, and a microlens 818 is formed on the microlens lower planarization layer 817.

13A to 13D are diagrams for explaining a conventional method for manufacturing a solid-state imaging device.
First, as shown in FIG. 13A, a light receiving portion 812 and a transfer electrode 813 are selectively formed on a semiconductor substrate 811, and flattening for flattening a convex portion formed by the transfer electrode 813 on the semiconductor substrate 811. A film 814 is formed. Next, as shown in FIG. 13B, a photosensitive resin containing a dye is applied onto the planarizing film 814, exposed through a mask, developed, and then green as the first color filter 815G. Form a pattern. Next, as shown in FIG. 13C, a photosensitive resin containing a dye is applied onto the planarizing film 814 and the first color filter 815G, exposed through a mask, developed, and then subjected to a second process. The red pattern which is the color filter 815R is formed. Although omitted in FIGS. 13A to 13D, the blue filter is formed in the same manner as the second color filter 815R which is a red filter. Thereafter, as shown in FIG. 13D, microlenses 818 are formed at positions corresponding to the microlens lower planarizing layer 817 and the respective light receiving portions 812. As described above, the solid-state imaging device 800 is manufactured.

  In addition, as a structure for improving the light collecting power with respect to the conventional solid-state imaging device 800, a structure having a transparent region having a different refractive index around the color filter and serving as a color filter optical waveguide is also proposed. (For example, refer to Patent Document 1).

  FIG. 14 is a cross-sectional view showing the structure of the solid-state imaging device disclosed in Patent Document 1. The parts other than the color filter have the same configuration as that of the solid-state imaging device 800 shown in FIG. 12, and are assigned the same reference numerals. Hereinafter, the color filter portion of the solid-state imaging device 900 will be described. In the solid-state imaging device 900, the transmissive region 916 is formed on the planarization film 814 by patterning a transmissive material over the entire periphery of the color filters 815G and 815R to be formed. Thereafter, as described above, coating, exposure, and development steps are performed to form color filters 815G and 815R corresponding to the respective light receiving portions. In the solid-state imaging device 900 configured as described above, the alignment accuracy is determined by the pattern in which the transmissive region portion 916 is formed. For this reason, even when the alignment accuracy at the time of creating the color filters 815G and 815R is low, there is no variation in alignment between the color filters, and it is possible to prevent color mixing with respect to the misalignment.

  Further, since the solid-state imaging device 900 includes an optical waveguide formed of a transparent material on the outer peripheral side surfaces of the color filters 815G and 815R, not only color mixing can be prevented but also the light collecting power can be improved, so that high sensitivity can be realized. .

JP 2007-147738 A

  However, when the pixel size becomes fine, the conventional solid-state imaging device 800 shown in FIG. 12 cannot collect light with the microlens 818 alone, and thus high sensitivity cannot be realized. In addition, since the resin forming the color filters 815G and 815R contains a pasted pigment, the aggregation of the pigment is likely to occur when the thinning proceeds and the amount of the contained pigment increases. That is, S / N (Signal to Noise ratio) deteriorates due to variations in pigment particle diameter. In addition, when the resin forming the color filter 815 is a dye type, the resistance is deteriorated and the dye oozes out to the peripheral pixels.

  In addition, in the solid-state imaging device 900 illustrated in FIG. 14, in addition to the light that passes through the color filter 815, there is light that enters from the transmissive region around the color filter 815. For this reason, the transmittance of light incident on each light receiving unit is increased at all visible light wavelengths, and there is a problem in that the degree of color modulation and color reproducibility are greatly deteriorated.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a solid-state imaging device capable of realizing high sensitivity even when the pixel size is reduced and a manufacturing method thereof.

  In order to achieve the above object, the solid-state imaging device of the present invention is a solid-state imaging device in which a plurality of pixels are arranged and each pixel includes a light receiving unit that converts incident light into an electrical signal. A color filter comprising first and second color filter units, and the first color filter unit is formed at the center of the color filter in the pixel surface direction. The second color filter unit is formed in a peripheral portion of the first color filter unit in a plane direction of the plurality of pixels, has substantially the same spectral characteristics as the first color filter unit, and The refractive index of the color filter portion is higher than the refractive index of the second color filter portion.

  With this configuration, the color filter itself has a light condensing effect by making a difference in refractive index between the first color filter portion that is the inner layer and the second color filter portion that is the peripheral layer. Can be made. That is, since a color filter can have a lens function for condensing light and an optical waveguide function for guiding light, a solid-state imaging device capable of realizing higher sensitivity even when the pixel size becomes fine is provided. Can do.

  The ratio of the refractive index of the first color filter portion to the refractive index of the second color filter portion is preferably 1.04 or more.

The difference in refractive index is assumed up to about F2 when F of the camera lens is used at the open end. Since the maximum incident angle at F2 is 14 degrees, there is light incident on the side wall of the color filter at 90 degrees −14 degrees = 76 degrees. In order to totally reflect the light, if the refractive index of the inner layer is Nu and the refractive index of the peripheral layer is Ns, Snell's law
Nu × sin (76 degrees) = Ns × sin (90 degrees)
Here, since sin (90 degrees) = 1,
Nu / Ns = 1 / sin (76 degrees) = 1.031
Therefore, if Nu / Ns> 1.04, a sufficient effect can be exhibited.

  The first color filter portion may be made of a material containing a dye, and the second color filter portion may be made of a material containing a pigment.

  With this configuration, the first color filter portion that is the inner layer is a dye type, and the second color filter portion that is the peripheral side layer is a pigment type, thereby preventing loss of color of the dye. A high S / N solid-state imaging device can be realized.

In order to achieve the above object, the manufacturing method of the present invention is a method of manufacturing a solid-state imaging device in which a plurality of pixels are arranged and each pixel includes a light receiving unit that converts incident light into an electrical signal.
Forming a light receiving portion constituting a pixel on a semiconductor substrate, and forming a color filter including first and second color filter portions above the light receiving portion in the corresponding pixel. The color filter forming step includes a first step of forming the first color filter at a central portion of the color filter in the surface direction of the pixel;
A second step of forming a second color filter having substantially the same spectral characteristic as that of the first color filter unit in a peripheral portion of the first color filter unit in the surface direction of the pixel, In the step, the refractive index of the first color filter portion is formed higher than the refractive index of the second color filter portion.

  In addition, in a camera including a solid-state imaging device having such an effect, high sensitivity, high color reproducibility, shading can be suppressed, and image quality can be improved.

  According to the present invention, it is possible to realize a solid-state imaging device capable of realizing high sensitivity even when the pixel size is reduced and a manufacturing method thereof.

It is sectional drawing of the solid-state imaging device in Embodiment 1 of this invention. 3 is a diagram illustrating a function of a color filter in the solid-state imaging device according to Embodiment 1. FIG. It is a figure for demonstrating the manufacturing method of the solid-state imaging device in Embodiment 1 of this invention. It is a figure for demonstrating the manufacturing method of the solid-state imaging device in Embodiment 1 of this invention. It is a figure for demonstrating the manufacturing method of the solid-state imaging device in Embodiment 1 of this invention. It is a figure for demonstrating the manufacturing method of the solid-state imaging device in Embodiment 1 of this invention. It is a figure for demonstrating the manufacturing method of the solid-state imaging device in Embodiment 1 of this invention. It is sectional drawing of the solid-state imaging device in Embodiment 2 of this invention. 6 is a diagram illustrating a function of a color filter in the solid-state imaging device according to Embodiment 2. FIG. It is a conceptual diagram of a camera lens with a short exit pupil distance. It is sectional drawing of the solid-state imaging device in Embodiment 3 of this invention. 6 is a diagram illustrating a function of a color filter in a solid-state imaging device according to Embodiment 3. FIG. It is sectional drawing of the solid-state imaging device in the modification 1 of Embodiment 3 of this invention. It is sectional drawing of the solid-state imaging device in the modification 2 of Embodiment 3 of this invention. It is a figure which shows one example of the shape of the color filter peripheral side layer which has a lens function or a waveguide function. It is sectional drawing of the conventional solid-state imaging device. It is a figure for demonstrating the manufacturing method of the conventional solid-state imaging device. It is a figure for demonstrating the manufacturing method of the conventional solid-state imaging device. It is a figure for demonstrating the manufacturing method of the conventional solid-state imaging device. It is a figure for demonstrating the manufacturing method of the conventional solid-state imaging device. It is sectional drawing which shows the structure of the solid-state imaging device in another prior art example.

  Hereinafter, a solid-state imaging device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
First, the configuration of the solid-state imaging device 100 according to Embodiment 1 of the present invention will be described. Here, the color filter is described below as being formed in a green checkered Bayer array of primary color filters.

FIG. 1 is a cross-sectional view of the solid-state imaging device according to Embodiment 1 of the present invention.
A solid-state imaging device 100 shown in FIG. 1 includes a semiconductor substrate 11, a light receiving unit 12, a transfer electrode 13, a planarizing film 14, color filters 15G and 15R, a microlens lower planarizing layer 17, and a microlens 18. With.

  The light receiving unit 12 is, for example, a photodiode that generates an electric charge according to the amount of incident light, and a plurality of the light receiving units 12 are formed on the semiconductor substrate 11.

  The transfer electrode 13 is for transferring charges generated in the light receiving unit 12, and is formed between adjacent light receiving units 12 on the semiconductor substrate 11.

  The planarizing film 14 is made of a light-transmitting material and is formed so as to be flattened by filling the convex portions generated by the transfer electrode 13.

  The color filter 15G is a green filter that is formed on the planarization film 14 at the position of the corresponding pixel in the solid-state imaging device 100 and transmits green light made of a resin containing a pigment such as a pigment. The color filter 15G includes a color filter inner layer 151G and a color filter peripheral side layer 152G.

  The color filter inner layer 151G is formed as a green filter with a size (referred to as an inner layer) smaller by about 0.3 μm than the pixel size on the planarizing film 14 at the corresponding pixel position. The color filter inner layer 151G may be any size smaller than the pixel size at the corresponding pixel position, and is not limited to the numerical values described above.

  The color filter peripheral layer 152G has a size substantially matching the pixel size on the outer side of the color filter inner layer 151G in the direction of the main surface of the semiconductor substrate 11, that is, on the peripheral layer of the color filter inner layer 151G. Green filters with different refractive indexes and the same system color are formed. The height (thickness) of the color filter peripheral side layer 152G in the normal direction of the main surface of the semiconductor substrate 11 is formed to be the same as the height (thickness) of the color filter inner layer 151G. Here, the same system color is synonymous with substantially the same spectral characteristics.

  Further, the color filter inner layer 151G and the color filter peripheral side layer 152G have different refractive indexes due to the difference in material, and the color filter inner layer 151G has a higher refractive index than the color filter peripheral side layer 152G. The refractive index ratio is preferably 1.04 or more. For example, if the refractive index of the color filter inner layer 151G is 1.6 and the refractive index of the color filter peripheral layer 152G is 1.5, the ratio is 1.067, and the color filter 15G collects green light. It has a lens function for making it light or a waveguide function for guiding green light.

The difference in refractive index is assumed to be up to about F2 when F of the camera lens is used at the open end. Since the maximum incident angle at F2 is 14 degrees, there is light incident on the side wall of the color filter peripheral layer 152 at 90 degrees minus 14 degrees = 76 degrees. In order to totally reflect the light, if the refractive index of the inner layer is Nu and the refractive index of the peripheral layer is Ns, Snell's law
Nu × sin (76 degrees) = Ns × sin (90 degrees)
Here, since sin (90 degrees) = 1,
Nu / Ns = 1 / sin (76 degrees) = 1.031
Therefore, if Nu / Ns> 1.04, a sufficient effect can be exhibited.

  Similarly, a color filter 15R is formed. That is, the color filter 15R is a red filter that is formed on the planarizing film 14 at the position of the corresponding pixel in the solid-state imaging device 100 and transmits red light made of a resin containing a pigment such as a pigment. The color filter 15R includes a color filter inner layer 151R and a color filter peripheral side layer 152G.

  The color filter inner layer 151R is formed as a red filter on the flattening film 14 at the corresponding pixel position with a size (referred to as an inner layer) smaller than the pixel size by about 0.3 μm.

  The color filter peripheral side layer 152R is formed on the outer side of the color filter inner layer 151R in the direction of the main surface of the semiconductor substrate 11, that is, on the peripheral side layer of the color filter inner layer 151R so as to have a size substantially matching the pixel size. The color filter peripheral layer 152R is formed as a red filter of the same color as a material having a refractive index different from that of the color filter inner layer 151R. The height (thickness) of the color filter peripheral layer 152R in the normal direction of the main surface of the semiconductor substrate 11 is formed to be the same as the height (thickness) of the color filter inner layer 151R.

  Further, the color filter inner layer 151R and the color filter peripheral side layer 152R have a difference in refractive index due to the difference in material. The color filter inner layer 151R has a higher refractive index than the color filter peripheral layer 152R. The refractive index ratio is preferably 1.04 or more. Accordingly, the color filter 15R has a lens function for condensing red light or a waveguide function for guiding red light.

  Although not shown in FIG. 1, the color filter 15B is similarly formed. Further, the color filters 15G, 15R, and 15B are arranged corresponding to the corresponding pixels, that is, the corresponding light receiving portions 12, and are arranged in a Bayer arrangement of, for example, a green checkered pattern. Therefore, FIG. 1 is a cross-sectional view in a direction in which the color filter 15B is not shown. Since the same applies to the following, description of the color filter 15B is omitted.

  The microlens lower planarizing layer 17 is formed on the color filters 15R and 15G. The upper surface of the microlens lower planarizing layer 17 is a substantially flat surface having almost no convex shape.

  The microlens 18 is a fine lens made of, for example, a transparent resin, and is formed on the upper surface of the microlens lower planarizing layer 17.

As described above, the solid-state imaging device 100 is configured.
FIG. 2 is a diagram illustrating the function of the color filter in the solid-state imaging device according to the first embodiment.

  In the solid-state imaging device 100, as shown in FIG. 2, the color filter peripheral side layer 152 and the color filter inner layer 151 formed of different refractive index materials constitute the color filter 15 in one pixel. As a result, the color filter 15 has a lens function for condensing light or a waveguide function for guiding light, and effectively condenses light that cannot be collected by the microlens 18 because the pixel size becomes fine. Can do. Therefore, the solid-state imaging device 100 can realize higher sensitivity.

  Next, a method for manufacturing the solid-state imaging device 100 having the above configuration will be described with reference to FIG.

  3A to 3E are diagrams for explaining a method of manufacturing the solid-state imaging device according to Embodiment 1 of the present invention.

  First, as shown in FIG. 3A, after forming the light receiving portion 12, the transfer electrode 13, and the planarizing film 14 on the semiconductor substrate 11, a photosensitive resin containing a dye is applied onto the planarizing film 14, After exposure through a mask, the photosensitive resin is developed to form the color filter inner layer 151G. Here, the color filter inner layer 151G containing a green pigment is formed in a pattern that is, for example, about 0.3 μm smaller than the size of the corresponding pixel.

  Next, as shown in FIG. 3B, a photosensitive resin having a color material of the same color as the colorant (green) of the color filter inner layer 151G is applied on the planarizing film 14, and exposed through a mask. The color filter peripheral layer 152G is formed by developing the photosensitive resin. Here, the color filter peripheral layer 152G containing a green pigment is formed in a pattern that is substantially the same as the size of the corresponding pixel.

  Next, as shown in FIG. 3C, a photosensitive resin containing a red pigment is applied on the planarizing film 14, exposed through a mask, and then the photosensitive resin is developed. Thus, the color filter inner layer 151R is formed. Here, the color filter inner layer 151R containing red (red) pigment is formed in a pattern smaller by about 0.3 μm, for example, than the corresponding pixel size.

  Next, as shown in FIG. 3D, a photosensitive resin having a colorant having the same color as the colorant (red) of the color filter inner layer 151R is applied on the planarizing film 14, and exposed through a mask. The color filter peripheral layer 152R is formed by developing the photosensitive resin. Here, the color filter peripheral side layer 152R containing a red (red) pigment is formed in a pattern so as to be approximately equal to the size of the corresponding pixel.

  Thereafter, as shown in FIG. 3E, a color filter 15R composed of the color filter inner layer 151R and the color filter peripheral side layer 152R, and a color filter 15G composed of the color filter inner layer 151G and the color filter peripheral side layer 152G Then, the microlens lower planarizing layer 17 is formed. Then, microlenses 18 are formed at positions corresponding to the respective light receiving portions 12 on the microlens lower planarizing layer 17.

  As described above, the solid-state imaging device 100 is manufactured.

(Embodiment 2)
In the second embodiment, another aspect of the color filter 15 (the color filter 15R and the color filter 15G) described in the first embodiment will be described.

  FIG. 4 is a cross-sectional view of the solid-state imaging device according to Embodiment 2 of the present invention. Elements similar to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The solid-state imaging device 200 illustrated in FIG. 4 includes the color filter inner layer 155R and the color filter peripheral side layer 156R that form the color filter 15R, and the color filter 15G with respect to the solid-state imaging device 100 according to the first embodiment. The configurations of the color filter inner layer 155G and the color filter peripheral side layer 156G are different.

  The color filter inner layer 155 </ b> R and the color filter inner layer 155 </ b> G are configured to have a forward tapered shape whose width becomes narrower upward from the surface of the semiconductor substrate 11. The color filter inner layer 155R and the color filter inner layer 155G having this shape can be easily formed by defocusing at the time of exposure.

  Further, as shown in FIG. 4, the color filter peripheral side layer 156R and the color filter peripheral side layer 156G are formed on the peripheral side layers so as to cover the forward tapered shape of the color filter inner layer 155R and the color filter inner layer 155G. Is formed. The rest of the configuration is the same as that of the color filter inner layer 151R and the color filter peripheral side layer 152R, and the color filter inner layer 151G and the color filter peripheral side layer 152G.

As described above, the solid-state imaging device 200 is configured.
FIG. 5 is a diagram illustrating the function of the color filter in the solid-state imaging device according to the second embodiment.

  In the solid-state imaging device 200, as shown in FIG. 5, the color filter inner layer 155, which is the inner layer of the color filter 15, is formed in a forward tapered shape, so that the light collecting effect can be further increased. That is, it is possible to efficiently collect the light even with respect to the oblique incident light and make the collected light incident on the light receiving unit 12. Thereby, for example, even when a camera lens with a short exit pupil distance as shown in FIG. 6 is used, it is possible to prevent problems such as shading. Here, FIG. 6 is a conceptual diagram of a camera lens with a short exit pupil distance.

  In addition, since the color filter peripheral side layer 156 having the same color is also provided outside the color filter inner layer 155, the optical path length passing through the color filter 15 is not impaired. Therefore, the solid-state imaging device 200 having excellent color reproducibility can be realized.

(Embodiment 3)
In the third embodiment, still another aspect of the color filter 15 (color filter 15R and color filter 15G) described in the second embodiment will be described.

  FIG. 7 is a cross-sectional view of the solid-state imaging device according to Embodiment 3 of the present invention. Elements similar to those in FIGS. 1 and 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The solid-state imaging device 300 shown in FIG. 7 differs from the solid-state imaging device 200 according to Embodiment 2 in the configuration of the color filter peripheral side layer 157, that is, the color filter peripheral side layer 157R and the color filter peripheral side layer 157G.

  As shown in FIG. 7, the color filter peripheral side layer 157R and the color filter peripheral side layer 157G are formed on the peripheral side layers so as to cover not only the peripheral side surfaces but also the upper surface of the color filter inner layer 155R and the color filter inner layer 155G. Is formed.

  In addition, since it is the same as that of the color filter peripheral side layer 152R and the color filter peripheral side layer 152G about others, description is abbreviate | omitted.

As described above, the solid-state imaging device 300 is configured.
FIG. 8 is a diagram illustrating the function of the color filter in the solid-state imaging device according to the third embodiment.

  In the solid-state imaging device 300, the color filter peripheral side layer 157R and the color filter peripheral side layer 157G are formed so as to cover not only the peripheral side surfaces of the color filter inner layer 155R and the color filter inner layer 155G but also the upper surface. The light collecting effect can be increased. That is, as shown in FIG. 8, it is possible to efficiently collect light even with respect to obliquely incident light and make the collected light incident on the light receiving unit 12. Thereby, for example, even when a camera lens with a short exit pupil distance as shown in FIG. 6 is used, it is possible to prevent problems such as shading.

(Modification 1)
The color filter inner layer 155 and the color filter peripheral side layer 157 have been described as being typically made of a resin containing a pigment type pigment, but are not limited thereto. For example, the color filter inner layer 155 may be made of a resin containing a dye type pigment, and the color filter peripheral layer 157 may be made of a resin containing a pigment type pigment. Such a case will be described with reference to FIG.

  FIG. 9 is a cross-sectional view of the solid-state imaging device according to Modification 1 of Embodiment 3 of the present invention. In addition, the same code | symbol is attached | subjected to the element similar to FIG. 7, and detailed description is abbreviate | omitted.

  The solid-state imaging device 310 shown in FIG. 9 is different from the solid-state imaging device 300 in that the color filter inner layer 255, that is, the color filter inner layer 255R and the color filter inner layer 255G are made of different materials. Consists of. Thereby, since the color filter 15 excellent in heat resistance and moisture resistance can be formed, the color loss of the dye can be prevented. Therefore, it is possible to realize the solid-state imaging device 310 having excellent durability and high S / N.

  In addition, the color material which forms the color filter inner layer 255 should just be made into the dye type using the formation method shown in FIG.

(Modification 2)
Further, the color filter peripheral side layer 157 may be made of a resin containing a dye type pigment, and the color filter peripheral side layer 157 is formed by utilizing the fact that the dye type pigment easily oozes from the resin by heating. It may be formed. In the second modification, such a case will be described.

  FIG. 10 is a cross-sectional view of the solid-state imaging device according to Modification 2 of Embodiment 3 of the present invention. In addition, the same code | symbol is attached | subjected to the element similar to FIG. 7, and detailed description is abbreviate | omitted.

  The solid-state imaging device 320 illustrated in FIG. 9 is different from the solid-state imaging device 310 in the material of the color filter peripheral side layer 257.

  The color filter peripheral side layer 257 includes a color filter peripheral side layer 257G, a color filter peripheral side layer 257R, and a color filter peripheral side layer 257B (not shown).

  As shown in FIG. 10, the color filter peripheral side layer 257 is a region where the dye is oozed out by forming the color filter inner layer 255 with a dye type and then heat-treating it. The exuded area is used as the color filter peripheral side layer 257.

The color filter peripheral side layer 257 is formed as follows, for example.
First, on the planarizing film 14, a dye-containing photosensitive resin containing a green dye is applied, exposed through a mask, and developed. Thereby, the color filter inner layer 255G is formed with a pattern smaller by about 0.3 μm than the size of the corresponding pixel.

  Next, similarly, a red (red) dye-containing photosensitive resin is applied, exposed through a mask, and developed. Thereby, the color filter inner layer 255R is formed with a pattern smaller by about 0.3 μm than the corresponding pixel size. Although not described, the blue color filter inner layer 255B is formed in the same manner.

  Next, the dye of the color filter inner layer 255 bleeds out by performing, for example, a heat treatment of 200 to 250 degrees and 5 to 10 minutes, and the oozed area is used as the color filter peripheral side layer 257. . Here, since the refractive index is lower as the dye concentration is lower, as a result, the color filter peripheral layer 257 has a lower refractive index than the color filter inner layer 255. In this way, the color filter 15R composed of the color filter inner layer 255, the color filter peripheral side layer 257, and the like can be a color filter having a condensing effect.

  As described above, since the solid-state imaging device of the present invention can have a lens function for condensing light in a color filter and an optical waveguide function for guiding light, higher sensitivity can be realized. Further, by using a dye type for the inner layer and a pigment type for the peripheral layer, it is possible to prevent the color loss of the dye, so that it is possible to realize a solid-state imaging device with excellent durability and high S / N. Therefore, it is possible to provide a solid-state imaging device capable of realizing high sensitivity even when the pixel size is reduced and a manufacturing method thereof.

  Although the case where the color filter has a two-layer structure of the color filter peripheral side layer and the color filter inner layer has been described in the present embodiment, the present invention is not necessarily limited to two layers. When a lens function for condensing light or a waveguide function for guiding light is provided by the same method as described above, it may be formed of three or more layers.

  Further, the shape of the color filter peripheral side layer is not limited to the case described in the present embodiment. There is a difference of 0.1 or more in the refractive index between the color filter inner layer and the color filter peripheral side layer, and the color filter inner layer should have a higher refractive index than the color filter peripheral side layer. Specifically, the refractive index ratio may be 1.04 or more, and the color filter may have a lens function for condensing light or a waveguide function for guiding light. For example, the shape of the color filter peripheral side layer 356 as shown in FIG. 11 may be used. That is, the width of the color filter 15 may be formed so that the upper part is smaller than the lower part. FIG. 11 is a diagram showing an example of the shape of the color filter peripheral side layer having the lens function or the waveguide function, and the same reference numerals are given to the same elements as those in FIG.

  In the present embodiment, the case where all the color filters have a two-layer structure of the color filter peripheral side layer and the color filter inner side layer has been described. However, the present invention is not necessarily applied to all color filters. For example, it may be applied only to a color filter having a concern about characteristics. By doing so, the color balance can be adjusted, and a solid-state imaging device with good color reproducibility can be realized. In other words, application to all color filters is not limited.

  In this embodiment, the color filter is described as a primary color filter (red, green, and blue), but a complementary color filter (yellow, cyan, magenta, and green) may be used. Good. Further, it goes without saying that various filters may be used in addition to the filter defined by the CIE XYZ color matching function, for example.

  In the present embodiment, the case where the solid-state imaging device is configured as a CCD image sensor is described as an example. It is good.

  Further, by using the solid-state imaging device according to the present embodiment for a digital still camera or a digital movie camera, a camera with high sensitivity, high S / N ratio, high color reproducibility, shading, line shading, and flicker is realized. be able to.

  The solid-state imaging device of the present invention has been described above based on the embodiment. However, the embodiment is merely an example, and the solid-state imaging device of the present invention has the configuration shown in this embodiment. It is not limited. Unless it deviates from the meaning of this invention, the form which carried out the various deformation | transformation which those skilled in the art can think to this embodiment, and the structure constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention. .

  The present invention can be used for a solid-state imaging device and a manufacturing method thereof, and in particular, can be used for a solid-state imaging device used in the fields of a CCD sensor, a MOS sensor, a digital still camera, and the manufacturing method thereof.

11, 811 Semiconductor substrate 12, 812 Light receiving part 13, 813 Transfer electrode 14, 814 Flattening film 15, 15G, 15R, 15B Color filter 17, 817 Microlens lower planarization layer 18, 818 Microlens 100, 200, 300, 310, 320, 400, 800, 900 Solid-state imaging device 151, 151G, 151R, 155, 155G, 155R, 255, 255G, 255R Color filter inner layer 152, 152G, 152R, 156, 156G, 156R, 157, 157G, 157R 257, 257G, 257R, 356 Color filter peripheral side layer 916 Transparent region portion

Claims (17)

A solid-state imaging device in which a plurality of pixels are arranged and each pixel includes a light receiving unit that converts incident light into an electrical signal,
A color filter formed on the light receiving portion of the corresponding pixel, the color filter including first and second color filter portions;
The first color filter portion is formed at a central portion of the color filter in the surface direction of the pixel,
The second color filter portion is formed in a peripheral portion of the first color filter portion in the plane direction of the plurality of pixels, and has substantially the same spectral characteristics as the first color filter portion,
The refractive index of the first color filter unit is higher than the refractive index of the second color filter unit. The solid-state imaging device according to claim 1, wherein a ratio between a refractive index of the first color filter unit and a refractive index of the second color filter unit is 1.04 or more. The solid-state imaging device according to claim 1, wherein the first color filter unit has a width in the surface direction of the plurality of pixels that decreases from the light receiving unit toward the corresponding pixel. The solid-state imaging according to any one of claims 1 to 3, wherein the second color filter unit is further formed on an upper portion of the first color filter unit in a normal direction of the plurality of pixels. apparatus. The second color filter in one adjacent pixel and the second color filter in the other adjacent pixel among the plurality of pixels are in contact with each other. Solid-state imaging device. 5. The solid-state imaging device according to claim 1, wherein the width of the color filter in the surface direction of the plurality of pixels is smaller in the upper part in the normal direction of the plurality of pixels than in the lower part. The solid-state imaging device according to claim 1, wherein the first color filter unit is made of a material containing a dye, and the second color filter unit is made of a material containing a pigment. Both the first color filter part and the second color filter part are made of a material containing a dye,
The solid-state imaging device according to claim 1, wherein a concentration of the dye in the first color filter unit is higher than a concentration of the dye in the second color filter unit. The solid-state imaging device further includes:
A transparent film formed on the color filter;
The solid-state imaging device of any one of Claims 1-8 provided with the micro lens formed on the said transparent film. The solid-state imaging device according to claim 1, wherein spectral characteristics of the first color filter unit and the second color filter unit are different from each other among adjacent pixels of the plurality of pixels. A method of manufacturing a solid-state imaging device, in which a plurality of pixels are arranged and each pixel includes a light receiving unit that converts incident light into an electrical signal,
Forming a light receiving portion constituting a pixel on a semiconductor substrate;
A color filter forming step of forming a color filter composed of first and second color filter portions above the light receiving portion in the corresponding pixel;
The color filter forming step includes a first step of forming the first color filter at a central portion of the color filter in a plane direction of the pixel;
A second step of forming a second color filter having substantially the same spectral characteristics as the first color filter unit on the periphery of the first color filter unit in the surface direction of the pixel,
In the first step, the refractive index of the first color filter portion is formed higher than the refractive index of the second color filter portion. The manufacturing method according to claim 11, wherein, in the first step, the first color filter unit is formed such that a width in a surface direction of the plurality of pixels decreases from the light receiving unit toward the corresponding pixel. Method. The manufacturing method according to claim 12, wherein, in the first step, the first color filter portion is formed by performing defocus exposure on a photosensitive material to be the first color filter portion. In the second step, the second color filter unit is further formed on the upper part of the first color filter unit in the normal direction of the plurality of pixels. The manufacturing method as described in. The width of the color filter in the surface direction of the plurality of pixels is formed in the color filter forming step so that the upper part in the normal direction of the plurality of pixels is smaller than the lower part. The manufacturing method of any one of Claims. In the first step, the first color filter portion is formed of a material containing a dye,
The manufacturing method according to claim 11, wherein in the second step, the second color filter portion is formed by causing the dye to ooze out from the material. further,
Forming a transparent film on the color filter;
The process of forming a microlens on the said transparent film | membrane. The manufacturing method of any one of Claims 11-16.

Images