JPS6039601A - Production of color solid-state image pickup element - Google Patents

Abstract

PURPOSE:To prevent staining by an alkali metal and to improve spectral transmission characteristic by making dyeing operation in the presence of a non- alkali metallic buffer agent. CONSTITUTION:The aq. photosetting gelatin soln. (photosensitive liquid) prepd. by adding ammonium dichromate to gelatin in which the content of alkali metal ion is decreased by an ion exchange treatment is coated on a solid-state image pickup element wafer of a CCD type and the coated layer is subjected to masked exposure then the uncured part (unexposed part) is dissolved away. A non-alkali metallic buffer agent contg. a cyan dye is then prepd. and the cured gelatin layer from which the uncured part is removed is dipped therein to perform coloring operation; thereafter the wafer is washed with a rinse liquid for the non-alkali metallic buffer agent and is dried, by which a cyan filter is obtd. A yellow layer is further provided on said filter so as to overlap partly on the cyan layer by the similar method, by which the 4-color filter of cyan, yellow, green and white is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a color solid-state image sensor.

2. Description of the Related Art In VTR cameras and the like, color image pickup tubes in which a light receiving section is provided with a micro color filter have been commonly used in order to extract color signals corresponding to color images.

-In recent years, various solid-state image sensors have been developed as devices to replace image pickup tubes, such as TATOEFA, CCD, BBD, and MOS (7). The practical application of a color solid-state image sensor (solid-state color image sensor) that combines a solid-state image sensor and a micro color filter has been studied, and some have already been put into practical use.

A color solid-state image sensor consists of a photoelectric conversion element, which is generally called a micropixel, and a flat image sensor integrated circuit (IC) that integrates a scanning circuit. It consists of a micro color filter in which several types of minute color separation filter elements (colored resin films) such as red, green, blue, cyan, magenta, and yellow are combined in a mosaic or stripe pattern. .

Color solid-state image sensors are generally manufactured by a method called a "bonding method" or an "on-wafer method."

Among these methods, the bonding method involves forming a color separation filter element corresponding to each pixel of a solid-state image sensor on a transparent support such as a glass plate to produce a micro color filter, and then bonding this to the surface of the solid-state image sensor. This method is used to create a color solid-state image sensor. Therefore, in this method, when adhering independently manufactured micro color filters to the surface of a solid-state image sensor, the operation is strictly controlled so that each color separation filter element accurately corresponds to each pixel of the solid-state image sensor. Is required.

On the other hand, the on-wafer method is a method in which a micro color filter is formed directly on a solid-state image sensor. Therefore, this on-wafer method has the advantage of being able to be incorporated into the manufacturing process of a solid-state image sensor, making it easier to manufacture a solid-state image sensor.

Note that the on-wafer method involves simultaneously manufacturing a large number of color solid-state image sensors by forming color separation filter elements corresponding to each pixel of each solid-state image sensor on a wafer on which a large number of solid-state image sensors are arranged. A single color solid-state image sensor is manufactured by cutting out a single solid-state image sensor (chip) from a wafer in which a large number of solid-state image sensors are arranged, and forming a color separation filter element on each chip. Although several methods (on-chip method) are known, in this specification, any of these methods is included in the on-wafer method.

A typical method of manufacturing a color solid-state image sensor, that is, a method of forming a micro color filter on the surface of the light-receiving part of the solid-state image sensor to produce a color solid-state image sensor, is to use a photocurable polymer. A coating solution containing the material is applied to the surface of the light receiving part of the solid-state image sensor to form a photocurable resin coating layer, and then light is irradiated to obtain a cured resin layer (substrate layer).
Next, this cured resin layer is dyed with a dye to form a colored resin film, and the same operation is repeated as necessary to form a plurality of colored resin films, thereby attaching a micro color filter to the solid-state image sensor. Here are some methods.

Since color solid-state image sensors are naturally desired to have high spectral transmission characteristics, various studies have been conducted with the aim of improving spectral transmission characteristics. We have also conducted research and development into excellent color solid-state imaging devices, but in the course of this research, we discovered that the colored resin film obtained when a cured resin film is dyed with an ordinary dye solution according to conventional methods does not necessarily have the desired spectral transmission characteristics. We found a problem in that it does not necessarily indicate the

According to the inventor's study, the reason for this is that each dye has a specific PV suitable for dyeing and/or expressing spectral transmission characteristics.
Since there is an H region and the pH range is relatively narrow, it is not always easy to maintain the pH of the dye solution to 1, and when two or more colored resin films are formed in layers, it is difficult to maintain the pH of the dye solution. It was found that the spectral transmission characteristics of the layer formed on the layer were easily affected by the pH of the resin layer-forming solution that was later formed on top of it, resulting in fluctuations (desorption of the dye, changes in the spectrum, etc.). did.

As a result of further investigation, the present inventors determined that the pH maintenance of the dye solution and the pH maintenance of the colored resin film described above are suitable for dyeing the dye solution and/or developing the spectral transmission characteristics of the dye used. It has been found that this can be achieved by adding a buffer in the pH range. However, commonly used buffers consist of a combination of an acid and a compound containing an alkali metal such as sodium, or a combination of multiple compounds containing an alkali metal. A metal-containing buffer may cause alkali metal contamination of the color solid-state image sensor, and there is a risk that the normal operation of the solid-state image sensor may be adversely affected.

In other words, a solid-state image sensor is made up of a flat IC with a highly integrated photoelectric conversion element and a scanning circuit, as mentioned above, and for this reason, a solid-state image sensor is susceptible to dirt, dust, alkali metals, etc. Contamination by impurities is highly disliked. Solid-state imaging devices contaminated with such impurities often do not exhibit predetermined characteristics, and such contamination directly leads to a reduction in product yield. Therefore, even in the process of attaching a micro color filter to a solid-state image sensor, it is necessary to take great care to avoid contamination with such impurities as much as possible.

In particular, contamination with a large amount of alkali metals such as sodium and potassium is likely to cause malfunction of the solid-state imaging device. Therefore, in order to avoid deteriorating the reliability of such products, it is desirable to reduce the amount of alkali metal mixed into color solid-state image sensors as much as possible. When manufacturing a color solid-state image sensor chip with an area of about 0.5 crn', it is desirable that the alkali metal content per chip is looppm or less; 50ppm
It is said that the following is desirable.

For the reasons mentioned above, the present inventor came up with the idea of using a non-alkali metal buffer from which substantially all alkali metals have been removed from the buffer to maintain the pHIm of the dye solution and the pH of the colored resin film. The present invention has been completed.

The present invention provides a method for manufacturing a color solid-state image sensor with less contamination by alkali metals and excellent spectral transmission characteristics, and involves dyeing one or more layers of resin film formed on the light-receiving part of the solid-state image sensor. A method for manufacturing a color solid-state imaging device, characterized in that the dyeing operation is carried out in the presence of a non-alkali metal buffer;
This method consists of a manufacturing method for a solid-state image sensor.

A common method for producing colored resin layers for color solid-state image sensors is to form a cured resin layer (substrate layer) on the surface of the light-receiving part of the solid-state image sensor, and then dye it with a dye to form a colored resin layer. This method is based on operations, and as described above, this method is already known, and such known techniques can be used when implementing the method for manufacturing a color solid-state image sensor of the present invention.

Water-soluble proteins such as gelatin are generally used as the polymer material forming the above-mentioned cured resin layer (substrate layer). For example, ordinary gelatin contains sodium ions (Na ) is approximately 100 to 20
00 ppm, and especially about 20 to 200 ppm of potassium ions (K+).

However, it is quite difficult to obtain such a color solid-state image sensor with a low alkali metal content from gelatin with a high alkali metal content such as the one mentioned above. The alkali metal content in gelatin prepared by 1, for example, about 150 PPm when treated with lime,
In the case of acid treatment, the content is as high as about 500 ppm, and the use of these gelatins poses a risk of causing contamination of the resulting color solid-state imaging device.

Furthermore, in the process of dyeing a cured resin film to obtain a colored resin film, dyes in the form of alkali metal salts have conventionally been used. However, these dyes in the form of alkali metal salts also pose a risk of causing alkali metal contamination of the colored resin film and, in turn, of alkali metal contamination of the solid-state imaging device.

The present inventors have developed an invention relating to the use of dyes that do not contain alkali metals (non-alkali metal dyes) in order to prevent alkali metal contamination as much as possible in the manufacturing process of conventional color solid-state image sensors as described above. , and the use of a water-soluble protein with a total alkali metal ion content of less than 20 ppmjJ as a base material for a colored resin film, and has already filed a patent application for these (Japanese Patent Application No. Application No. 139856, Application No. 57-154503, Application No. 57-178991, and Application No. 57-208563).

Therefore, in the present invention, it is desirable to use a polymer material with a low alkali metal content as the polymer material for forming the resin film, and it is also desirable to use a non-alkali metal dye as the dye.

For the above reasons, the present invention provides a method for manufacturing a color solid-state image sensor, which comprises dyeing one or more resin films formed on the light-receiving area of a solid-state image sensor, in which the resin film has a total content of alkali metal ions. A method for manufacturing a color solid-state image sensor is formed from a polymeric material with a concentration of 20 ppm or less, and the dyeing operation is carried out using an aqueous solution of a non-alkali metal dye in the presence of a non-alkali metal buffer. That is desirable.

Next, the present invention will be explained in detail using the above-mentioned preferred embodiments as an example.

In this preferred embodiment of the present invention, in the production of a color solid-state image sensor, the total content of alkali metal ions is 20p
By using a polymeric material (usually a water-soluble protein) below pm and carrying out the dyeing operation with a non-alkali metal dye aqueous solution in the presence of a non-alkali metal buffer,
The present invention aims to prevent the risk of contamination of a solid-state image sensor with alkali metals, etc., and improve the spectral transmission characteristics of a colored resin film, thereby making it possible to manufacture a highly reliable color solid-state image sensor.

Preferred polymeric materials used in the present invention include water-soluble synthetic polymeric materials and natural polymeric materials.

The materials commonly used for this purpose are water-soluble proteins, such as gelatin, casein, etc., which have been highly dealkalyzed with metal ions.

As a method for highly dealkalyzing metal ions from water-soluble proteins, a method using ion exchange treatment is preferably used because alkali metal ions can be removed particularly efficiently. Ion exchange treatment of water-soluble proteins can be carried out by using a known ion exchange resin having alkali metal ion exchange performance and passing an aqueous solution of water-soluble protein through a column filled with the ion exchange resin. .

In the present invention, preferred polymeric materials used as the base material of the colored resin film formed on the light receiving part of the solid-state image sensor are:
The total content of alkali metal ions in the dry state is 20. p
pm or less. And the total content of alkali metal ions is preferably less than or equal to loppm,
Particularly preferably, it is 5 ppm or less.

In the present invention, a water-soluble protein is an example of a preferably used polymeric material, and a particularly preferred water-soluble protein is gelatin.

In the present invention, it is preferable to attach the micro color filter to the light receiving section of the solid-state image sensor by an on-wafer method, which is carried out, for example, as follows.

First, the total content of alkali metal ions as mentioned above is 2
A photocurable resin solution is prepared by adding a photocurable substance to a water-soluble protein having a concentration of 0 ppm or less. This photocurable resin solution is applied to the surface of the light receiving part of the solid-state image sensor to form a photocurable resin coating layer, and the surface is irradiated with light that has passed through the exposure pattern to form a mosaic pattern on the resin coating layer. Alternatively, a cured resin layer in the form of a stripe is formed.Next, this layer is washed with an appropriate solvent to dissolve and remove the uncured portion, thereby obtaining a cured resin layer in the form of a mosaic or stripe.

Next, this cured resin layer is dyed with one of red, green, blue, cyan, magenta, or yellow dyes to form a color separation filter element (colored resin film) I.

Various acid dyes, direct dyes, and reactive dyes are already known as dyes used for this dyeing, but in the present invention, non-alkali metal dyes are used to prevent alkali metal contamination. It is preferable.

Non-alkali metal dyes preferably used in the present invention include those of the general formula (I): D-(SOsX)m (I) ( However, D is a dye moiety such as an azo dye, a bisazo dye, or a phthalocyanine dye; Examples include dyes that do not contain .

Similarly, preferred non-alkali metal dyes include:
This method is also disclosed in Japanese Patent Application No. 57-154503 and No. 57-178991 filed by the present applicant.

In the above general formula (I), examples include those in which X is a hydrogen atom, and those in which X is a mixed system of a cation consisting of a plurality of nonmetallic atoms and a hydrogen atom.

In addition, the dyeing solution used for dyeing the resin film in the present invention contains a non-alkali metal buffer that imparts a pH11 pH value suitable for the dye used.

Various compositions are known as buffers that provide various pH buffer systems depending on the purpose, but most of them are a combination of an acid and a compound containing an alkali metal such as sodium, or a combination of an acid and a compound containing an alkali metal such as sodium. Such an alkali metal-containing buffer causes alkali metal contamination of the color solid-state image sensor as described above, and is therefore not suitable for the purpose of the present invention. Not yet.

Therefore, in the present invention, non-alkali metal buffers are used in place of these alkali metal-containing buffers. Such non-alkali metal buffers can be obtained, for example, by replacing the alkali metal moiety of the compound forming the alkali metal-containing buffer with ammonia or various organic amines.

That is, for example, a buffer composition consisting of acetic acid and sodium acetate (pH = 3.6 to 5.6) is changed to a buffer composition consisting of acetic acid and ammonium acetate, so that the buffering capacity is not significantly changed. It can be a non-alkali metal buffer without any Similarly, a buffer composition (pH
= 8°94-11.37) by using a buffer composition consisting of ammonium carbonate and ammonium hydrogen carbonate, and by using a buffer composition consisting of citric acid and disodium hydrogen phosphate (pH = 2. 2 to 8.0) can be made into non-alkali metal buffers without significantly changing the respective buffering capacities by using a buffer composition consisting of citric acid and diammonium hydrogen phosphate.

In addition, the buffering agent mentioned above should be used at a pH suitable for the dye used.
It can be easily selected in consideration of the H region.

After the above staining operation is completed, a washing operation is performed using a rinsing solution. In the present invention, it is preferable to use an aqueous solution containing a non-alkali metal buffer as this rinsing solution. Examples of non-alkali metal buffers include those mentioned above.

By adding a non-alkali metal buffer to the staining solution and rinsing solution as described above, it is possible to improve the spectral transmission characteristics of the colored resin film while avoiding alkali metal contamination. The durability of the liquid in use (pH stability during repeated use) is significantly improved.

Next, a color contamination prevention layer is formed on the color separation filter element formed in this way, and a colored resin film is further formed on it in the same manner, and the surface is irradiated with light that has passed through another exposure pattern. Then, another mosaic or stripe-like cured portion is generated in the resin layer. Then, in the same manner, the uncured resin portion is removed and the cured resin layer is dyed with another dye to form a color separation filter element (colored resin film) M. Further, if necessary, the operation for forming color separation filter elements is repeated to form a desired color separation filter group, and finally, a surface coating layer is formed to complete the formation of the micro color filter.

In addition, during or before and after each of the above operations,
Although operations such as exposing the bonding pad portion necessary for circuit formation may also be included, since these operations are not directly related to the present invention, their explanation will be omitted.

Further, by subjecting each colored resin film to a surface modification treatment for preventing color staining, it is also possible to omit the provision of the color stain preventing layer. This color stain prevention treatment method is as follows:
A method of preventing color staining of the colored resin film by treating the surface of the colored resin film obtained by dyeing with an aqueous solution of tannic acid and acetic acid and an aqueous solution of an alkali metal salt of antimonyl tartrate can be mentioned. Note that by changing the alkali metal salt of antimonyl tartrate to ammonium antimonyl tartrate, one of the objects of the present invention, which is to prevent alkali metal contamination of a solid-state imaging device, can be more effectively achieved. A non-alkali metal buffer may be added to this color stain prevention treatment solution, and prior to such color stain prevention treatment, treatment with an aqueous hardening agent solution and/or heat treatment may be used. It is also preferable to perform a hardening treatment, and for the colored resin film that has been subjected to color stain prevention treatment, it is preferable to wash it using a rinsing solution containing a non-alkali metal buffer, as in the case after the staining treatment described above. You may do so.

In the present invention, since the colored resin film can easily maintain a desired pH value, its spectral transmission characteristics are improved, and it is possible to stably maintain its excellent spectral transmission characteristics for a long period of time.

Furthermore, a polymer material with highly reduced alkali metal ion content is used as the base material of the colored resin film formed on the solid-state image sensor, and a non-alkali metal dye is used as the dye. When an aqueous solution containing a non-alkali metal buffer is used in the operation, the resulting color solid-state image sensor is particularly effectively protected from contamination by harmful alkali metal ions, which improves the reliability of the color solid-state image sensor. Therefore, it is possible to manufacture a practically excellent color solid-state image sensor.

Next, examples of the present invention will be shown.

[Example 1] Ammonium dichromate was added to gelatin whose alkali metal ion content had been reduced by ion exchange treatment to prepare a photocurable gelatin aqueous solution (photosensitive solution). When the alkali metal ions contained in this gelatin photosensitive solution were analyzed by atomic absorption spectrometry, the Na+ content was 1.65 ppm, and the + content was 0.50 ppm.

This gelatin photosensitive liquid is applied onto a CCD-type solid-state image sensor wafer (which contains a large number of CCD-type solid-state image sensors and has a protective layer made of phosphosilicate glass on its surface) to form a coating layer. formed. A mask (exposure pattern) consisting of a mosaic pattern was placed on the gelatin photosensitive liquid coated layer, and exposure was performed. Next, the exposed coating layer is washed with hot water to remove the uncured areas (unexposed areas).
By dissolving and removing the hardened gelatin layer (resin film; each convex part of the hardened gelatin layer is
A solid-state image sensing device wafer was obtained in which a solid-state image sensing device wafer was attached with a photosensitive portion (formed at a portion corresponding to each of the photosensitive portions (pixels) of the solid-state image sensing device).

A non-alkali metal buffer solution (pH = approximately 6; containing 29.6 g of ammonium acetate and 0.960 mJl of acetic acid per IJI of water) separately containing a cyan dye ((tetra)pyridinium of copper phthalocyanine (tetra)sulfonic acid IM) The above-mentioned hardened gelatin layer (resin film) was immersed in the gelatin layer (resin film) and colored.Next, the colored resin film was soaked in a non-alkali metal buffer rinse solution (pH=about 4.
4; 2.31 g of ammonium acetate and acetic acid per 1A of water.
20 mjL) and then dried.

The spectral transmission characteristics of the cyan filter formed as described above were determined by the conventional method using an alkali metal-containing cyan dye (
The spectral transmission characteristics were equivalent to those of a cyan filter manufactured by dyeing with (tetra)sodium salt of copper phthalocyanine (tetra)sulfonic acid).

[Example 2] According to the method of Example 1, a cyan filter was formed on a CCD solid-state image sensor wafer.

Separately, Megitol N, B, S, Liquid (
BAYER@) diluted 40 times with water and adjusted to pH 4 with acetic acid.
Prepare a resist dyeing treatment bath adjusted to 40%
After heating to ℃, add 4 of the above cyan filters to it.
The zero-order cyan filter that had been immersed for 2 minutes was washed by immersing it in a buffer solution (pH 4.4) prepared from acetic acid and ammonium acetate for 2 minutes, and then left in an oven at 150° C. for 30 minutes for heat treatment.

On top of the cyan filter that has been subjected to resist dyeing treatment as described above,
A yellow colored resin film (yellow filter) was formed by the same operation as that for forming the cyan filter. However, for the yellow dyeing operation, a non-alkali metal buffer solution (pH = approximately 5; 8 g of ammonium acetate IO per 1 U of water) in which a pyridinium salt of Suminol Milling Kai Yellow MR (manufactured by Sumino Kagaku Kogyo ■) was dissolved was used. This was carried out by immersing the cured resin film for 8 minutes in acetic acid (containing 4 ml. After washing with 19 parts of water (containing 2.31 g of ammonium acetate and 4.2 mft of acetic acid per portion), this was left in an oven at 150° C. for 30 minutes and heat treated.

The spectral transmission characteristics of the yellow filter formed as described above were determined by the conventional method using an alkali metal-containing yellow dye (
Suminol Milling Yellow MR: Sodium salt)
The spectral transmission characteristics were equivalent to those of a yellow filter manufactured by dyeing with .

Further, even after forming the yellow filter, the spectral transmission characteristics of the cyan filter showed the same level as before forming the yellow filter.

The colored resin layer formed as above allows cyan, yellow, green (overlapping part of cyan and yellow),
A micro color filter was formed consisting of four colors: white (non-resin portion) and white (non-resin portion).

On the above micro color filter, a copolymer of ethyl p-phenylene diacrylate and equimolar amount of 1,4-bis(β-hydroxyethoxy)-cyclohexane (as a sensitizer, 2-benzoylmethylene-1- Methyl-β-
Contains 2% naphthothiazoline by weight)
A resin coating layer was formed, and this was heat-treated (prebaked) by leaving it in an oven at 150°C for 30 minutes. The bonding pad part and the guising cut part were covered on this, and the pixel part was exposed. Place the exposure no turn,
This resin coating layer was then exposed to ultraviolet rays and developed with γ-butyrolactone to elute and remove the unexposed portions of the resin (the bonding pad portion and the guising cut portion). This was heat-treated (post-baked) by leaving it in an oven at 170°C for 40 minutes.

As a result of the above, a color solid-state imaging device with a low alkali metal content and excellent spectral transmission characteristics was obtained.

Patent applicant - Fuji Photo Film Co., Ltd. Agent Patent attorney Yasuo Yanagawa

Claims (1)

[Claims] l. A method for manufacturing a color solid-state image sensor, which comprises dyeing one or more resin films formed on a light-receiving part of a solid-state image sensor, characterized in that the dyeing operation is carried out in the presence of a non-alkali metal buffer. Manufacturing method of color solid-state image sensor. 2゜The total amount of alkali metal ions in the resin film is 20p.
The color solid-state imaging device according to claim 1, wherein the color solid-state imaging device is formed from a polymeric material having a particle size of pm or less, and the dyeing operation is carried out using an aqueous solution of a non-alkali metal dye in the presence of a non-alkali metal buffer. Device manufacturing method. 3. The method for producing a color solid-state imaging device according to claim 2, characterized in that a water-soluble protein having a total alkali metal ion content of 110 PP or less is used as the polymer material for forming the 3° resin film. 4゜Water-soluble protein has a total content of alkali metal ions of 5
4. The method for producing a color solid-state image sensor according to claim 3, wherein the gelatin is less than ppm. 5. The color solid-state imaging device according to claim 4, wherein the water-soluble protein is gelatin whose alkali metal ion content is reduced by ion exchange treatment and whose total alkali metal ion content is 5 ppm or less. manufacturing method. 6. After the dyeing operation, the colored resin film obtained is washed with an aqueous solution containing a non-alkali metal buffer, the method for producing a color solid-state image sensor according to claim 1. . 7. Force 2 - A method for manufacturing a color solid-state image sensor according to any one of claims 1 to 6, characterized in that the solid-state image sensor is manufactured on-wafer.