JP2008021699A - Solid-state imaging apparatus, its manufacturing method, and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus which is superior in line gray level characteristic. <P>SOLUTION: The solit-state imaging apparatus is provided with a plurality of light receivers 2 that are formed like a matrix in a semiconductor substrate 1, a transfer electrode 3, a first flattening film 4, a second flattening film 8, a microlens 9, and G-color filters 5, B-color filters 6 and R-color filters 7 that are arranged respectively on the light receivers 2. The G-color filter 5 is provided with a B-color filter 6' or an R-color filter 7' with different transparent wavelengths in the nearly central part of the G-color filter 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a color solid-state imaging device having a color filter formed on a light receiving portion, a manufacturing method thereof, and a camera having the color solid-state imaging device.

  In recent years, along with the reduction in the chip size of the solid-state imaging device and the increase in the number of pixels, digital cameras, digital movie cameras, camera-equipped mobile phones, and the like have been reduced in size and performance.

  In addition, color solid-state imaging devices including color filters are also known as these solid-state imaging devices. A conventional color solid-state imaging device is, for example, a primary color filter composed of a combination of red (R), blue (B) and green (G), or cyan (C), magenta (M), yellow (Y) and green ( A complementary color filter composed of a combination of G) is laminated on a light receiving surface of light receiving elements arranged in a matrix of solid-state image sensors in a predetermined pattern so that one color corresponds to one light receiving element. As described above, the color filter laminated on the light receiving surface of the light receiving element is generally referred to as an “on-chip filter”.

An example of a color solid-state imaging device is disclosed in Patent Document 1. As shown in FIG. 9, the color solid-state imaging device has a structure in which one pixel unit 11 is divided into a plurality of sections each storing a plurality of signal charges having different spectral sensitivities. That is, one pixel unit 11 is divided into a small pixel having an R spectral sensitivity, a small pixel having a G spectral sensitivity, and a small pixel having a B spectral sensitivity, and a transfer formed on the side of the pixel unit 11. A signal charge read from each small pixel is transferred by a path (not shown). According to this color solid-state imaging device, since the interval between small pixels having different spectral sensitivities can be narrowed, generation of false signals and false colors can be suppressed, and image data with excellent color reproducibility can be obtained.
JP 2004-172278 A

  By the way, in a color solid-state imaging device, since a color filter provided with Gr and Gb filters having different spectral characteristics is generally used, there is a problem that line shading is deteriorated.

  At this time, in the solid-state imaging device described in Patent Document 1, one pixel unit is further divided into a plurality of sections and a transfer path is formed on the side of the pixel unit. There is also a problem that the area decreases. There is also a problem that the manufacturing method becomes complicated. There is also a problem that color mixing from adjacent pixels is likely to occur.

  In view of the above problems, an object of the present invention is to provide a solid-state imaging device having good line density characteristics.

  In order to achieve the above object, a solid-state imaging device according to the present invention includes a plurality of light receiving portions formed in a matrix in a semiconductor substrate, and a color filter layer disposed on the plurality of light receiving portions, In the color filter layer on a predetermined light receiving portion, color filters having different transmission wavelengths are two-dimensionally arranged. In other words, the solid-state imaging device has a semiconductor substrate, a light receiving element formed in a matrix on the semiconductor substrate, and a color filter layer formed on the light receiving element and made up of three or more color filters. In the color filter layer, a plurality of color filters are two-dimensionally arranged on one light receiving element.

  Accordingly, the color filter has portions having different transmission wavelengths. Therefore, since a B color filter or an R color filter can be formed on a part of the G color filter and used as a Gr and Gb color filter, the spectral characteristics of Gr and Gb are prevented from differing. be able to. As a result, a color solid-state imaging device with good line shading characteristics can be realized.

  Further, the present invention is a method of manufacturing the solid-state imaging device, wherein a light receiving part forming step of forming a plurality of light receiving parts in a semiconductor substrate, a color filter is formed on the plurality of light receiving parts, A method for manufacturing a solid-state imaging device, comprising: a hole forming step for forming a hole in a color filter; and an embedding step for embedding a color filter having a transmission wavelength different from that of the color filter having the hole formed in the hole. You can also. In other words, the method includes a step of forming light receiving elements on a semiconductor substrate in a matrix, and a step of sequentially forming color filters of at least first to third colors on the light receiving element. In at least one of the steps of forming a color filter for a color, a color filter having the same color as the color filter formed in the step is formed in the center of any one of two color filters different from the color filter. It can also be set as the manufacturing method of the solid-state imaging device characterized by this.

  As a result, a color solid-state imaging device having good line shading characteristics can be manufactured.

  The present invention may also be a camera including the solid-state imaging device.

  As a result, a camera with good line shading characteristics can be realized.

  According to the solid-state imaging device of the present invention, since B or R light is added to G light, the spectral characteristics of Gr and Gb can be made the same. As a result, line shading can be suppressed and image quality can be improved. Moreover, according to the method for manufacturing a solid-state imaging device of the present invention, a solid-state imaging device having such an effect can be manufactured. In addition, according to the camera of the present invention, since the solid-state imaging device having such an effect is provided, it is possible to realize a camera capable of suppressing line shading and improving image quality.

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

  First, the configuration of the color solid-state imaging device according to the present embodiment will be described. Here, a color solid-state imaging device in which the primary color filter is a green checkered Bayer array will be described.

  FIG. 1 is a plan view showing an example of the color arrangement of the primary color filter according to the present embodiment.

  As shown in FIG. 1, in the primary color filter according to the present embodiment, a B color filter 6 ′ or an R color filter 7 ′ is disposed at a substantially central portion of the G color filter 5.

  2A is a cross-sectional view of the color solid-state imaging device according to the present embodiment (cross-sectional view taken along line aa ′ in FIG. 1), and FIG. 2B is a cross-sectional view of the color solid-state imaging device ( It is sectional drawing in the bb 'line of FIG.

  As shown in FIGS. 2A and 2B, in the color solid-state imaging device according to the present embodiment, a well region 1a is formed in a semiconductor substrate 1, and one photodiode is formed in the well region 1a. A plurality of light receiving portions 2 formed of (light receiving elements) are formed in a matrix. A transfer electrode 3 is formed on the semiconductor substrate 1 so as to be positioned between the light receiving portions 2. On the semiconductor substrate 1 and the transfer electrode 3, a first planarizing film 4 having translucency is formed so as to fill the concave portion generated by the transfer electrode 3. On the first planarization film 4, a G color filter 5 having a transmission wavelength region in the green light wavelength region and a transmission wavelength region in the blue light wavelength region are positioned above each light receiving unit 2. B color filters 6 and 6 ′ and R color filters 7 and 7 ′ having a transmission wavelength range in the wavelength range of red light are respectively formed on the color filters. 2 A planarizing film 8 is formed. On the second planarizing film 8, microlenses 9 are formed so as to concentrate the incident light on each light receiving portion 2 so as to be positioned above each light receiving portion 2. ing.

  Here, in each G color filter 5, a B color filter 6 ′ or an R color filter is provided at a substantially central portion (above the substantially central portion of the light receiving portion 2 that receives light that has passed through the G color filter 5). 7 'is arranged, and a G color filter is arranged in a peripheral part thereof (above the peripheral part of the light receiving unit 2 that receives light that has passed through the G color filter 5). Different color filters are two-dimensionally arranged.

  As described above, according to the color solid-state imaging device of the present embodiment, each G color filter 5 has a portion in which a B color filter 6 'or an R color filter 7' having a different transmission wavelength is formed. Therefore, since B or R light is added to G light, it is possible to prevent the spectral characteristics from being different between Gr and Gb. As a result, a color solid-state imaging device with good line shading characteristics can be realized.

  Next, a method for manufacturing the solid-state imaging device according to the present embodiment will be described. 3 (a), 4 (a), 5 (a), 6 (a), 7 (a), and 8 (a) illustrate a method for manufacturing a color solid-state imaging device according to the present embodiment. It is sectional drawing for demonstrating (sectional drawing in the aa 'line of FIG. 1), FIG.3 (b), FIG.4 (b), FIG.5 (b), FIG.6 (b), FIG.7 (b) ) And FIG. 8B are cross-sectional views (cross-sectional view taken along the line bb ′ of FIG. 1) for explaining the method for manufacturing the color solid-state imaging device.

  First, as shown in FIGS. 3A and 3B, a plurality of light receiving portions 2 are formed in the semiconductor substrate 1 and a transfer electrode 3 is formed on the semiconductor substrate 1 by a known method. Acrylic resin is applied onto the entire surface of the semiconductor substrate 1 and the transfer electrode 3 by spin coating. Then, the 1st planarization film | membrane 4 is formed by heat-drying acrylic resin. Then, for example, a positive photoresist 5a colored in green is applied to the surface of the first planarizing film 4 so as to have a uniform thickness.

  Next, as shown in FIGS. 4A and 4B, the positive photoresist 5 a is irradiated with light using a mask 15. The positive photoresist 5a immediately below the portion of the mask 15 where the opening is formed and where there is no pattern is exposed by light transmitted through the opening. On the other hand, the positive photoresist 5a immediately below the portion of the mask 15 where the pattern is present is not exposed because light is blocked by the pattern. Therefore, after the light irradiation, when a development process is performed, the positive photoresist 5a remains only in a portion corresponding to the pattern of the mask 15, and the G color filter 5 is formed on the surface of the first planarizing film 4. It is formed. At this time, each of the G color filters 5 is provided on the mask 15 every other row direction and every other column direction with respect to the plurality of light receiving portions 2 formed in a matrix on the semiconductor substrate 1. A plurality of openings are formed so as to be arranged. That is, a plurality of openings are formed so that a plurality of G color filters 5 having a checkered pattern are formed on the light receiving surface. The mask 15 is formed with a plurality of openings for exposing the central portion of each G color filter 5 so that a hole is formed in the central portion of each G color filter 5. The shape of the hole in the central portion of the color filter 5 is not limited. For example, the hole may have a polygonal shape instead of a circular shape.

  Next, as shown in FIGS. 5A and 5B, a positive photoresist 6a colored in blue is spun so as to cover the entire G color filter 5 and the first planarizing film 4. Apply by coat.

  Next, as shown in FIGS. 6A and 6B, the positive photoresist 6 a is irradiated with light using a mask 16. The positive photoresist 6a immediately below the portion of the mask 16 where the opening is formed and where there is no pattern is exposed to light transmitted through the opening. On the other hand, the positive photoresist 6a directly under the portion where the pattern is present in the mask 16 is not exposed because light is blocked by the pattern. Therefore, after the light irradiation, after a development process, the positive photoresist 6a remains only in a portion corresponding to the pattern of the mask 16, and the B color filter 6 on the surface of the first planarizing film 4 6 'is formed. At this time, an opening is formed in the mask 16 so as to be positioned above the G color filter 5 in the portion of the mask 16 shown in FIG. 6A, and the mask 16 shown in FIG. In the portion, an opening is formed over the entire region.

  Next, as shown in FIGS. 7A and 7B, a positive photoresist 7a colored in red so as to cover the entire G color filter 5 and B color filters 6, 6 ′. Is applied by spin coating.

  Next, as shown in FIGS. 8A and 8B, the positive photoresist 7 a is irradiated with light using a mask 17. The positive photoresist 7a immediately below the portion of the mask 17 where the opening is formed and where there is no pattern is exposed by light transmitted through the opening. On the other hand, the positive photoresist 7a immediately below the portion where the pattern is present in the mask 17 is not exposed because light is blocked by the pattern. Therefore, after the light irradiation, after a development process, the positive photoresist 7a remains only in a portion corresponding to the pattern of the mask 17, and the R color filter 7 on the surface of the first planarizing film 4 7 'is formed. At this time, in the portion shown in FIG. 8A, an opening is formed over the entire area of the mask 17 so that the mask 17 is positioned above the G color filter 5 in the portion shown in FIG. 8B. An opening is formed.

  Finally, an acrylic resin is applied onto the color filter layer composed of the G color filter 5, the B color filters 6, 6 ', and the R color filters 7, 7' by spin coating, followed by heating and drying. Then, the second planarizing film 8 is formed. Thereafter, a microlens 9 is formed on the surface of the second planarizing film 8. As a result, the color solid-state imaging device shown in FIGS. 2A and 2B is completed.

  As described above, according to the manufacturing method of the color solid-state imaging device of the present embodiment, a color solid-state imaging device with good line density characteristics can be realized.

  As described above, the solid-state imaging device and the manufacturing method thereof according to the present invention have been described based on the embodiment. However, the present invention is not limited to this embodiment. The present invention includes various modifications made by those skilled in the art without departing from the scope of the present invention.

  For example, although the example in which the color filters are formed in the order of G, B, and R has been described in the above embodiment, the order in which the color filters are formed is not limited to this, and may be any order. Further, although a positive type photoresist is used, a negative type photoresist may be used. In this case, the patterns of the masks 15, 16, and 17 may be changed so that the light transmitting area and the blocking area are reversed. In the above embodiment, the color filter is formed by photolithography, but the color filter may be formed by etching. In this case, a hole is formed in the G color filter 5 by etching, and another B or R color filter is poured into the hole to form the R color filter 7 ′ and the B color filter 6 ′.

  In the above embodiment, primary color filters (red, green, and blue) are used as color filters, but complementary color filters (four colors of yellow, cyan, magenta, and green) may be used. In addition, it goes without saying that various filters are effective.

  In the above embodiment, the color solid-state imaging device is constituted by a CCD image sensor, but it goes without saying that the same effect can be obtained even if constituted by a CMOS image sensor.

  In the above embodiment, a Bayer color filter is used as the color filter. However, the present invention is not limited to this as long as color filters having different transmission wavelengths are arranged on the adjacent light receiving portions 2 and the color filters on the adjacent light receiving portions 2 are arranged in a two-dimensional array.

  The color solid-state imaging device according to the above embodiment may be used for a digital still camera or a digital movie camera. In this case, a camera with less line shading and flicker can be realized.

  The present invention can be used for a color solid-state imaging device, a manufacturing method thereof, and a camera.

It is a top view which shows an example of the color arrangement | positioning of the primary color filter which concerns on embodiment of this invention. (A) It is sectional drawing (sectional drawing in the a-a 'line of FIG. 1) of the color solid-state imaging device concerning this Embodiment. FIG. 2B is a sectional view of the color solid-state imaging device (a sectional view taken along line b-b ′ in FIG. 1). (A) It is sectional drawing (sectional drawing in the a-a 'line of FIG. 1) for demonstrating the manufacturing method of the color solid-state imaging device concerning this Embodiment. (B) It is sectional drawing for demonstrating the manufacturing method of the color solid-state imaging device (sectional drawing in the b-b 'line of FIG. 1). (A) It is sectional drawing (sectional drawing in the a-a 'line of FIG. 1) for demonstrating the manufacturing method of the color solid-state imaging device concerning this Embodiment. (B) It is sectional drawing for demonstrating the manufacturing method of the color solid-state imaging device (sectional drawing in the b-b 'line of FIG. 1). (A) It is sectional drawing (sectional drawing in the a-a 'line of FIG. 1) for demonstrating the manufacturing method of the color solid-state imaging device concerning this Embodiment. (B) It is sectional drawing for demonstrating the manufacturing method of the color solid-state imaging device (sectional drawing in the b-b 'line of FIG. 1). (A) It is sectional drawing (sectional drawing in the a-a 'line of FIG. 1) for demonstrating the manufacturing method of the color solid-state imaging device concerning this Embodiment. (B) It is sectional drawing for demonstrating the manufacturing method of the color solid-state imaging device (sectional drawing in the b-b 'line of FIG. 1). (A) It is sectional drawing (sectional drawing in the a-a 'line of FIG. 1) for demonstrating the manufacturing method of the color solid-state imaging device concerning this Embodiment. (B) It is sectional drawing for demonstrating the manufacturing method of the color solid-state imaging device (sectional drawing in the b-b 'line of FIG. 1). (A) It is sectional drawing (sectional drawing in the a-a 'line of FIG. 1) for demonstrating the manufacturing method of the color solid-state imaging device concerning this Embodiment. (B) It is sectional drawing for demonstrating the manufacturing method of the color solid-state imaging device (sectional drawing in the b-b 'line of FIG. 1). It is a top view which shows the structure of the conventional color solid-state imaging device of patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 1a Well area | region 2 Light-receiving part 3 Transfer electrode 4 1st planarization film 5 G color filter 5a, 6a, 7a Positive type photoresist 6, 6 'B color filter 7, 7' R color filter 8 First 2 Planarizing film 9 Microlens 11 Pixel part 15, 16, 17 Mask

Claims (7)

A plurality of light receiving parts formed in a matrix in a semiconductor substrate;
A color filter layer disposed on the plurality of light receiving parts,
A solid-state imaging device, wherein color filters having different transmission wavelengths are two-dimensionally arranged in the color filter layer on a predetermined light receiving unit. In the color filter layer on the predetermined light receiving portion, the color filter of the first transmission wavelength and the color filter of the second transmission wavelength are two-dimensionally arranged,
2. The solid-state imaging device according to claim 1, wherein a color filter having a third transmission wavelength is disposed in the color filter layer on the light receiving unit located next to the predetermined light receiving unit. In the color filter layer on the predetermined light receiving portion, the color filter having the first transmission wavelength is disposed above a substantially central portion of the predetermined light receiving portion, and a peripheral portion of the substantially central portion of the predetermined light receiving portion. The solid-state imaging device according to claim 1, wherein a color filter having the second transmission wavelength is disposed above. The first transmission wavelength is a wavelength of red light or blue light,
The solid-state imaging device according to claim 3, wherein the second transmission wavelength is a wavelength of green light. A method of manufacturing the solid-state imaging device according to claim 1,
A light receiving portion forming step of forming a plurality of light receiving portions in the semiconductor substrate;
Forming a color filter on the plurality of light receiving portions, and forming a hole in the color filter; and
A method of manufacturing a solid-state imaging device, comprising: embedding a color filter having a transmission wavelength different from that of the color filter having the hole formed therein. The method for manufacturing a solid-state imaging device according to claim 5, wherein the formation of the color filter, the perforation of the color filter, and the embedding of the color filter are performed by photolithography. A camera comprising the solid-state imaging device according to claim 1.

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