JPS6041872B2 - Color solid-state image sensor board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color solid-state image sensor, and more particularly to a color solid-state image sensing device in which a color separation filter consisting of a non-Al light-shielding layer and a colored filter element is disposed directly or via an adhesive layer on a light-receiving surface. Regarding an image sensor.

To date, as solid-state image sensors, CCD type, MO
Various methods such as the S method, the BBD method, and the CID method have been proposed and are in use.

In these solid-state image sensors, it is necessary to distinguish and output the difference in the amount of input light depending on the location of the light-receiving part or light-receiving surface, so the light-receiving part is divided into unit areas called pixels, and each pixel is divided into unit areas called pixels. play a role. This pixel is an independent functional element. It may also be a form in which the continuum is virtually divided. Such a solid-state image sensor can be thought of as a collection of point detectors, but in current image transmission or image recording systems such as television systems, if the output is parallel, subsequent signal processing and transmission will be difficult. The output is required to be a time-series signal because it is too complex to handle. In this sense, a solid-state image sensor is a device that has the function of converting incident light with a two-dimensional distribution into a time-series electrical signal, and basically consists of the following Ξ functions. Photoelectric conversion function: A function that converts incident light into an amount of electricity corresponding to its intensity in the photosensitive area of each pixel on the light-receiving surface, and is usually a process in which carriers are excited by the energy of the absorbed light. is often used.

To maintain resolution, independent photoelectric conversion is performed for each pixel. Charge accumulation function: An electrical signal is extracted as an output as a result of photoelectric conversion, but the output must be a time-series signal, and when considering individual moments, only the signal from one pixel is generated. will be output, and other pixels will be at rest during that time.

On the other hand, since the incident light always reaches the idle pixels, if this information is integrated and retained during the idle period, the incident light at that moment will be reflected at each moment of scanning to each pixel. Rather than outputting a corresponding output, the image sensor as a whole can output more output than the number of images. This is the accumulation function. Scanning/output function: In order to take out outputs according to the discharge state of the charges accumulated in each pixel sequentially over time, the MOS and CID methods take out the output using the XY designation method, and the CCD method, In the BBD method, output is extracted using a signal transfer method. In order to construct a color solid-state image sensor plate using a solid-state image sensor with such a Ξ function, conventionally, incident light is passed through a prism or a dichroic mirror to convert red light,
A three-plate system has been used in which green light and blue light are separated and irradiated to three solid-state image sensors individually. However, these three-plate systems not only require three solid-state image sensors, making the device expensive, but also use a prism or mirror system for color separation, which increases the weight and size of the image sensor, and also increases the registration cost. This is a major drawback of color solid-state imaging devices that aim to be small, lightweight, and low-priced. The present inventors have conducted research to improve the drawbacks of the conventional color solid-state imaging device described above and provide a compact, lightweight, and low-cost color solid-state imaging device. The photosensitive part (
(Throughout this specification, the term "solid-state image sensor plate" is used to refer to a solid-state image sensor that has a colored filter on its light-receiving surface.) (Showa 5 Detailed Patent Application No. 92991).

By combining one of such solid-state image sensor plates with a lens, a solid-state image sensor corresponding to a single-plate system can be constructed extremely easily. Since such a solid-state imaging device uses only one solid-state imaging device, there is no registration problem, and there is no need for a color separation section using mirrors, prisms, etc., and the peripheral circuitry is also simplified. As a result, the imaging device can be dramatically reduced in weight and size. However, due to inertia, the solid-state image sensor used in the technology related to the above-mentioned patent application No. 92991 of 1972 has an A for light shielding on the non-light-sensitive area existing in each pixel of the light-receiving surface.
According to subsequent research by the present inventors, it was found that the use of such an A1 film for shielding light from non-exposed areas is not preferable. In other words, such an A1 film has been formed by etching the A1 film provided on one surface at the final stage of manufacturing a solid-state image sensor, together with each electrode wiring made of N, but the etching characteristics of the A1 film are not so good. Furthermore, as each pixel becomes smaller with the demand for smaller solid-state image sensors, pattern accuracy that can keep up with the smaller size becomes impossible. For this reason, 1 hO of the photosensitive area
There is a drawback that light enters a non-photosensitive area having a certain degree of photosensitivity, degrading the characteristics of the entire solid-state image sensor. In the present invention, a solid-state image sensor excluding a conventional N light-shielding film (the term "solid-state image sensor" used in the present specification for describing the present invention refers to A) a solid-state image sensor excluding a light-shielding film ), a non-N light-shielding film with excellent pattern accuracy is provided on the non-photosensitive area in conjunction with the manufacturing method, and
By providing a colored filter element on the photosensitive area that overlaps with the light-shielding film at the edges, the color separation characteristics of the color solid-state image sensor plate are improved, noise is reduced, and the formation of the colored filter element is facilitated. That is.

Hereinafter, the present invention will be explained in more detail in conjunction with the prior art with reference to the drawings.

The solid-state image sensor board according to the above-mentioned prior art has a solid-state image sensor 1'' (11 is a light receiving section, 11a is a pixel, 12 is a pixel, 1 is a storage section, 13 is a shift register section, and 14 is a bonding pad section for wire bonding), and a partially enlarged cross-sectional structure as shown in FIG. 2 taken along the line ■-■ in FIG. Si substrate, 22 is a channel stopper by diffusion or ion implantation, 22, 23 are non-photosensitive parts, 24 is an oxide film of SlO2, 25 is a polysilicon transport electrode, 26 is SiO2,
Starting from a solid-state image sensor 1'' having a passivation layer made of a thin film of an insulating material such as PSC (phosphosilicate glass) or Si3N4, and an A1 light-shielding film 27, the photosensitive portion 1 of each pixel is
As shown in FIG. 3, colored filter elements 3R, 3G, and 3B of different colors are formed on 1b. Also, 22,2
The non-photosensitive part 3 is not only used in the configuration shown in Fig. 2;
There are cases where a thick oxide film is used, a threshold electrode is used, etc. Furthermore, the configuration of the CCD is different if it uses an interline transfer method. On the other hand, in the color solid-state image sensor plate of the present invention, FIG.
Starting from the solid-state image sensor 1 whose cross-sectional structure is shown in FIG. 4 excluding
and 23, and at the same time, colored filter elements 3R, 3G, and 3B are formed on the photosensitive portion 11b to be wider than the area of each photosensitive portion, and are overlapped with the non-A1 light blocking film 28 at the ends thereof. It has a similar configuration.

A method for manufacturing such a solid-state image sensor plate will be described in detail below.

The solid-state imaging device 1 itself according to the present invention as shown in FIG. 4 can be obtained in exactly the same manner as the conventional one except that the A1 film is not provided on the non-photosensitive parts 22 and 23.

In other words, for commercially available silicon wafers,
As shown in FIG. 6, a plurality of solid-state image sensing devices 1 are manufactured on a wafer at once by ordinary wafer processes such as thin film formation, impurity diffusion, and photolithography. At this stage, the solid-state image sensor 1 is in the state shown in FIG. 1, and the light receiving section 11 is formed, for example, by a set of pixels 11a in a grid pattern as shown in FIG. 1, and the storage section 12 and The shift register section 13 is also divided into unit elements. Further, a passivation layer is provided on the light receiving section 11, the storage section 12, and the shift register section 13. In order to obtain the color solid-state image sensor plate of the present invention as shown in FIG. 5, first, as shown in FIG.
and 23, a non-Al light shielding film 28 is provided.

In this case, the non-A1 light-shielding film may be provided on the storage section 12 and the shift register section 13, and since these parts do not require particularly strict pattern accuracy, they may remain as A1 light-shielding films. Various types of non-A1 light shielding film 28 can be used.

Specific examples and general manufacturing methods thereof are as follows.
(i) After forming a film using normal film forming techniques such as coating a black colored film solution of organic polymer resin, (i) Plate making (
For example, in the case of photosensitive resin, baking, printing, etc. (11) After forming the film, first color it by wet or dry dyeing, and then apply color to the colored resin film. Resist plate making and plasma etching. Alternatively, it is patterned by sputter etching or the like.

More specifically, dichromate, chromate, diazo compound, etc. are added as photosensitizers to water-soluble resins such as gelatin, gelatin, gelatin, polyvinyl alcohol, and polyvinylpyrrolidone. An aqueous solution of the resin is coated, dried, exposed through a mask having a pattern of non-exposed areas 23, developed, and the patterned resin film is colored with a desired black dye.

In addition, resin films made of cellulose resin, vinyl resin, acrylic resin, polyamide, polyester, urethane resin, etc. can be dyed with dyes such as disperse dyes, oil-soluble dyes, and cationic dyes before or after patterning. can. (b) CrlZr,. W. ．． Ti,. Metal thin films such as Ta are formed by vacuum evaporation, sputtering, etc., and patterned by ordinary photo-engraving techniques.

(c) Black films of organic dyes, pigments, and inorganic pigments These are formed into films by vacuum evaporation, sputtering, etc., and patterned using plate-making techniques.

Specifically, after resist plate making, patterning is performed by plasma etching, sputter etching, or ordinary wet etching. (iv) Inorganic black film For example, a metal film such as A1 is formed, and this is converted into a metal oxide film such as AI2O3 by anodizing or the like, and at the same time, dyeing properties are imparted and dyed.

Patterning can be performed by applying general plate-making techniques. (e) PbS. ．． SnS,. CuS. ．． FeO. ．．
Low reflective inorganic film such as CuO These can be formed by vacuum evaporation or sputtering, and patterned by photo-engraving technology.

(f) After forming a surface nitride film of a metal thin film such as Cr (approximately 1000 Å thick), CrNx is further formed to a thickness of 400 Å.

In the present invention, the light shielding film has an optical temperature of 2
．． The thickness is appropriately selected and determined so as to be 0 or more, preferably about 3.0 or more.

The thickness is preferably 0.1 to 2.0P771. The range shall be . Further, it is particularly preferable that the reflectance is 10% or less. Among these non-A1 light-shielding films, colored films of organic polymer resins are preferred because they are easy to manufacture, have insulating properties, have low reflectance, and have good pattern accuracy.

Next, as shown in FIGS. 7B, c, and d (detailed layer structure inside the solid-state image sensor 1 is omitted in these figures), a color separation filter consisting of three colors, for example, red, green, and blue, is formed. In this case, the red filter element 3R, the green filter element 3G, the blue filter element 3B, and the blue filter element 3B are sequentially formed on the photosensitive section 11b so that the area is larger than the area of each photosensitive section 11b, and their ends overlap with the non-A1 light shielding film 28. do.

(Of course, the formation order of 3R, 3G, and 3B is arbitrary). FIG. 7d is an example of the color solid-state imaging device plate of the present invention, which is the same as FIG. 5. Specific examples and general manufacturing methods of various colored filter elements are as follows.

(a) Colored film of organic polymer resin This is exactly the same as the formation of the non-N light-shielding film 28, except that the hue to be colored and therefore the dye etc. are different.

Note that colored filter elements 3R, 3G,
A photoresist, a dye resist, and a bleaching agent can be used as necessary to sequentially form 3B. (B)
Colored films of organic dyes or pigments themselves are obtained by forming detergents or pigments into films by vacuum evaporation or the like, followed by resist plate making and patterning by plasma etching, sputter etching, or the like.

(c) An inorganic colored film, such as an Al film, is anodized to form an insulating and dyeable Al. After forming the O3 film, it is colored with an alumite dye and patterned using a conventional method.

(d) Inorganic pigment thin film CdS. A colored filter is obtained by forming a thin film of a pigment such as CdSe in a vapor phase, and patterning it by sputter etching, wet etching, etc., or directly patterning it through a mask.

(e) Multilayer interference thin film MgF2, SlO. ．． Low refractive index material such as SjO2 and Zr
O2, TlO2, Zns. ．． After alternately depositing 7 to 11 layers of high refractive index material such as ceO2, wet etching and dry etching. Create a pattern by etching.

The formation of the colored filter itself is described in the above-mentioned Showa 5 Tsubo Patent Application No. 92991 and 9299? Since the invention is not particularly different from the invention of the above invention, the specifications of these applications may be used as reference as necessary. cormorant.

However, in the present invention, a non-Al light shielding film 28 is formed in place of the A1 light shielding film 27 on the non-photosensitive parts 22 and 23 of each pixel, and the photosensitive part 11a is placed over the light sensitive part 11a with the end thereof overlapping with the non-Al light shielding film 28. Colored filter element 3R with a larger area than 11a,
Form 3G and 3B. The first advantage of having a large colored filter element is that the color separation filter forming process can be performed on the premise that white light will not bypass the filter element and cause noise such as blooming. It should be easy.

That is, FIG. 8 is an example of the color solid-state image sensor plate of the present invention corresponding to FIG. 7d, which was obtained as a result of inaccurate mask alignment in the process of forming the colored filter element. . For example, when a negative photosensitive material is used as the layer to be colored, the width of the photosensitive area 11b is T1 non-N light shielding film 28
If the width of the mask is t, and the width of the white swath (light transmitting part corresponding to the element forming part) is T+t, the alignment of the mask for forming the filter element 3G is proper, but the position of the mask for forming the filter element 3G is
The R and 3B alignments are each t/to the left and right, respectively.
It's off by 2. However, the color separation filter shown in FIG. 8 obtained in this manner has no problems in terms of performance. That is, for example, when T=20μ and t=6μ, the alignment accuracy of the mask for forming colored filter elements is ±3μ.
(=t/2) is good. The second advantage of having a large colored filter element is that for the same reason as explained in FIG. 8, the precision of the mask for forming the colored filter element is as high as the conventional one (for example, ±0.25μ). Not necessary, ±t/2 (for example, if t=6μ, ±3μ)
This makes it easy to manufacture the mask.

In particular, a mask for forming a colored filter element requires high precision, so a repeater is used for its production, but in general, an unevenness of about 0.1 to 0.5 microns occurs during repeating. Conventionally, masks with such repeat unevenness could not be used, but in the case of the solid-state imaging device of the present invention, since the structure is as described above, even a mask with repeat unevenness can be used without problems. In the above, an example in which the non-A1 light-shielding film 28 and the colored filter elements 3R, 3G, and 3B are formed directly on the solid-state image sensor 1 has been described, but the solid-state image sensor plate of the present invention is shown in FIG. As shown in FIG.
Light shielding film 25 and colored filter elements 3R, 3G, 3B
to form the color separation filter plate 4, and the non-Al
It can also be obtained by accurately aligning the light-shielding film with the non-photosensitive parts 22 and 23 of the solid-state image sensor 1 as shown in FIG. 9b and bonding them together with an adhesive or the like.

Such an indirect method is effective in eliminating possible adverse effects on the solid-state image sensor in the process of forming the non-Al light-shielding film 28 and the colored filter elements 3R, 3G, and 3B. As long as the non-Al light-shielding film 28 formed on the transparent substrate is accurately formed and accurately aligned with the non-photosensitive parts 22 and 23 of the solid-state image sensor, during the formation of the colored filter element described above and the formation of the colored filter element. The effect of simplifying the time work can also be obtained. The above-mentioned manufacturing method for obtaining the color solid-state image sensor plate of the present invention may be applied from the beginning by guising the solid-state image sensor formed on a silicon wafer as shown in FIG. 6 into individual chips, but it is preferable. A method is adopted in which the method is applied as is to a solid-state image sensor formed on a wafer, and then diced.

Further, although the above example shows an example in which the colored filter elements are arranged in a grid pattern corresponding to each pixel, the solid-state image sensor plate of the present invention can be arranged in other mosaic or stripe shapes. It can also be constructed using a colored filter element.

Furthermore, in addition to the CCD solid-state image sensor using the frame transfer method described above, there are also interline transfer method CCDl and other BBD. ．． The color solid-state image sensor plate of the present invention can also be obtained by applying the present invention to solid-state image sensors such as MOS. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A frame transfer method was used on a 3-inch wafer, with the surface shape shown in Figure 6 and the partial cross-sectional shape shown in Figure 4. After manufacturing a CCD solid-state image sensor using conventional wafer processes such as vapor phase growth, impurity diffusion, photolithography, and vapor deposition techniques, a 1.2μ aqueous photosensitive plate made of ammonium dichromate is placed on the light receiving surface. After coating and drying, a mask with a predetermined shape is accurately aligned, and after contact exposure, the non-exposed areas are removed with warm water and a colored film is formed on the non-exposed areas of the light receiving area of each solid-state image sensor. do.

After drying this colored film, it is dyed in a first black dye bath containing an acid dye, washed with water, dyed again in a second black dye bath containing hematin, washed again with water, and then post-treated in a third bath. Then, by further washing with water and drying, a non-N light-shielding film is formed. The dyeing bath composition and dyeing conditions for forming a non-A1 light-shielding film are as follows.

First black dye...80°C 14 minutes Karajan●
Flag-BGL (manufactured by Nippon Kayaku Co., Ltd.)
25yinoacetic acid 60cc water
2000cc second black dye...
・・60℃12 minutes Hechiman
10y water 1
000cc Third black dye...25°C, 2 minutes Potassium dichromate 50y water
The optical temperature of the 1500 cc non-N black light-shielding film obtained by the above method was 3.0.

Next, resist dyeing treatment is performed with tannic acid and ammonyl potassium tartrate solution.

This state is shown in FIG. 7a. Then, in the same manner, an aqueous photosensitive solution is applied to a thickness of 0.8 .mu.m, dried, exposed using a mask of a predetermined shape, developed, and dyed and resist dyed for the first colored filter element 3R.

This state is shown in FIG. 7b. Following the same process, C,
As shown in d, a second colored filter element 3G1 and a third colored filter element 3B are formed. In order to form these colored filter elements, a mask aligner is used to accurately align the positions and form a colored film, but since the tolerance is limited to the width of the non-A1 light-shielding film, workability is only greatly improved. Therefore, the manufacturing yield of the colored filter element part was greatly improved. Next, in order to protect the colored filter elements, etc., a transparent CBR resist of 1.0 μm, which is a cyclized butadiene-based negative resist manufactured by Japan Synthetic Rubber Co., Ltd., was applied.
After coating, exposure and development were carried out using a mask having a predetermined shape to form a protective film in areas other than the bonding pad region, followed by heat treatment at 160° C. for 30 rpm to produce a color solid-state imaging device plate of the present invention. Thereafter, a single-chip color solid-state camera was fabricated by performing dicing into chips, die bonding, wire bonding, packaging, etc. using conventional methods. The dye bath composition of each colored filter element is as follows.

3R Dye Bath Kayano Remilling Red RS (manufactured by Nippon Gunpowder Co., Ltd.) 1 part acetic acid
3 parts water 1 (1) part 3G dyebath Brilliant in Blue (manufactured by Hoechst) 1 part Suminol Yellow MR (manufactured by Sumitomo Chemical Co., Ltd.) 1 part acetic acid
3 parts water
1 Ube 3B Dye bath Kayanol Saiani'/6B (manufactured by Nippon Gunpowder Co., Ltd.) 1
Part acetic acid 3 parts Water 1 (1) part Example 2 After forming a two-layer structure CrOx/Cr film by depositing 200A of CrOx and 700A of Cr on a glass substrate of 47Tgf1t, plate making and etching were carried out. Then, a non-A1 light-shielding film made of a CrOx/Cr layer is formed as shown at 28 in FIG. 9a so as to correspond to the non-photosensitive parts 22 and 23 of the solid-state image sensor.

Next, the colored filter elements 3R, 3G, and 3B are sequentially formed by the usual manufacturing method for dyed filters with bar.

The method for forming a stone-colored filter element is to apply an aqueous photosensitive solution consisting of ammonium dichromate, dry it,
After accurately aligning a mask with a predetermined shape and contact exposure, it is developed and colored. After the film is formed, it is washed with each dye bath so that it has a predetermined spectral transmittance. Thereafter, resist dyeing treatment may be performed as in Example 1, or a transparent resin layer such as acrylic may be formed as an intermediate layer to prevent color mixing. Each dye bath for each colored filter element was the same as in Example 1. The same one was used. Further, for the purpose of protecting the colored filter elements, a transparent acrylic resin was applied and cured by heating to produce a color separation filter section having a non-Al light-shielding film having the structure shown in FIG. 9a. In this case as well, even if a work error occurs in the formation position of the colored filter/element by the width of the non-A1 light-shielding film made of CrOx/Cr, there is no problem and the manufacturing yield can be improved. Next, the color separation filter plate is cut using a dicing saw to match the size of the light receiving portion of the solid-state image sensor.

For the color separation filter plate, multiple chips may be formed on the same substrate and then cut. In this way, a color separation filter plate is manufactured, and after a wafer process, a solid-state image sensor having the structure shown in FIG.
After wire bonding and packaging are completed, the adhesive is accurately aligned and bonded using a mixture of epoxy adhesive Cemedine 1565 and curing agent D in a ratio of 100:15. A single-plate color solid-state image sensor plate was fabricated using this method.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view of one solid-state image sensor formed on a silicon wafer, FIG. 6 is a plan view of a silicon wafer on which a plurality of silicon wafers are formed, and FIGS. 9 to 9 are partial sectional views of a solid-state image sensor, a solid-state image sensor plate, or a semi-finished product taken along the line ■-■ in FIG.
The figure shows a conventional solid-state image sensor, FIG. 3 shows a solid-state image sensor plate according to the prior art, and FIG. 4 shows a solid-state image sensor used in the present invention.
FIG. 5 is an example of the solid-state imaging cable plate of the present invention, and FIGS. 7a-d
8 shows a misaligned solid-state image sensor plate of the present invention corresponding to FIG. 5, and FIGS. 9 a-b show a manufacturing method of the solid-state image sensor plate of the present invention using a bonding method. are shown respectively. 1... Solid-state image sensor (1'' is a conventional solid-state image sensor), 11... Light receiving section, 11a... Pixel, 11b... Pixel photosensitive section, 12... ...accumulation section, 1
3...Shift register part, 14...Bonding pad part, 21...Si substrate, 22,
23... Non-photosensitive area (22... Drain, 2
3... Channel stopper), 24... Oxide film, 25... Transfer electrode, 26... Passivation layer, 27... AI light shielding film, 28...
... Non-A1 light shielding film, 3R, 3G, 3B ... Colored filter element, 4 ... Color separation filter plate, 41 ... Transparent substrate.

Claims (1)

[Claims] 1. Non-A is placed on the non-photosensitive area of each pixel on the light-receiving surface of the solid-state image sensor.
1. A color solid-state image sensor plate, characterized in that a light-shielding film is formed, each colored filter element is formed on a photosensitive part to be wider than the area of each light-sensitive part, and the ends thereof are overlapped with a non-Al light-shielding film. .