JPS6223282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a color filter.

Color filters of various solid-state imaging devices such as CCDs are mainly formed of organic substances such as proteins.

Proteins are used as materials for the photosensitive film of color filters because proteins are superior to other substances in terms of processability and dyeability. For this purpose, proteins such as casein, gelatin, etc. are mainly used as materials for color filters.

The spectral sensitivity (light transmittance characteristics) of the color filter is
It largely depends on the dyeing state and the base film thickness. Therefore, the base film thickness of the color filter is an extremely important factor in determining the spectral characteristics of the color filter.

By the way, proteins are unstable in an aqueous solution state and easily undergo polymerization, decomposition, etc., resulting in various inconveniences when used. In addition, various factors can be considered as factors that make the protein aqueous solution unstable. These factors include, for example, hydrolysis by chemicals, decomposition by microorganisms such as bacteria, polymerization due to changes in ionic strength in an aqueous solution, and polymerization due to oxidation (especially oxidation of SH groups contained in protein molecules). (Formation of S--S bond) etc. can be considered. Among these factors, factors other than polymerization due to oxidation can be suppressed by means such as selection of chemicals, use of preservatives, non-addition of salts, and non-dilution. Also,
In particular, in order to suppress decomposition by microorganisms such as bacteria, in addition to adding preservatives, a method of storing foods at low temperatures to suppress bacterial activity is actually adopted.

However, in addition to these factors, many proteins contain cysteine with an SH group, and this SH group is extremely easily oxidized, and is easily oxidized by oxygen in the air, forming S-S bonds. It has the property of forming and polymerizing. Therefore, it is impossible to suppress protein polymerization due to oxidation by the above-mentioned means. In order to prevent protein polymerization due to oxidation, it is possible to operate under oxygen-free conditions, but this requires special equipment, and it is difficult to set up such anoxic conditions. is expensive and difficult to handle, and is therefore not preferred in practice. As another method capable of suppressing oxidative polymerization of proteins without using such special conditions, the use of SH group-protecting reagents such as β-mercaptoethanol has been proposed and has been successful. However, since ammonium dichromate and the like, which can be used as a photosensitizer for forming color filters, are oxidizing agents, there are naturally some restrictions on the use of the above-mentioned SH group protecting reagent. Therefore, there has been a further desire for a method that can stabilize an aqueous protein solution in a short period of time without being subject to such restrictions.

In addition, if an aqueous protein solution is stored in its natural state or in a cold place such as a refrigerator for a long time, oxidation will progress and it will reach a certain level of viscosity, and if the solution is applied, a base coating film with a somewhat uniform thickness can be obtained. . However, in this case, it takes a long time for the aqueous protein solution to reach a certain level of viscosity, and since the aqueous protein solution is unstable, determining the time required requires forming a coating each time. This method requires time and effort such as measuring the film thickness, and is extremely inconvenient in practical use.

Therefore, the present invention particularly provides a method for producing a color filter that can increase the viscosity of an aqueous protein solution to stabilize it in a short period of time, and form a base coating film having a substantially uniform thickness. The purpose is to

The method for producing a color filter according to the present invention involves forcibly oxidizing a photosensitive composition for a color filter consisting of a protein and a photosensitizer in the presence of an oxygen-containing gas to increase the viscosity and stabilize it. The method is characterized in that it is applied to the substrate of a filter to form a base coating film having a uniform thickness, and then the base coating film is dyed.

The protein and photosensitizer used in the present invention are not particularly specified, and any protein that has been conventionally used for the same purpose can be used. In addition, as a protein, it is particularly preferable to use a protein containing cysteine having an SH group in its molecule as a component, but any protein that can be made to have a high viscosity by undergoing forced oxidation as described below can be used. can do.

The forced oxidation applied in the method according to the invention is carried out in the presence of an oxygen-containing gas. The oxygen-containing gas may be oxygen itself or a gas containing oxygen such as air, and the oxygen concentration in the gas is not particularly limited. Examples of methods for forced oxidation include physically stirring the aqueous protein solution. The time for performing this forced oxidation is generally about 1 to 3 hours, but it can be changed as appropriate depending on conditions such as the initial viscosity of the raw protein aqueous solution and the stirring speed before the start of forced oxidation. The time can be easily selected by one skilled in the art.

The aqueous protein solution made highly viscous through forced oxidation is applied to the substrate of the color filter by spin coating, screen printing, dipping, or other suitable means. The coating method may be a conventional method, and the conditions may be appropriately selected according to a conventional method. Further, there is no particular limitation on the thickness of the coating film, and in particular, a thickness of about 1 to 5 μm is sufficient.

Note that a photosensitizer such as ammonium dichromate is added to the aqueous protein solution applied to the substrate of the color filter, and the amount used may be the same as conventionally used.

The photoresist film of the aqueous protein solution applied as described above is formed on a color filter, for example, in the following manner. First, a mask of a predetermined shape is placed on this photoresist film, and after being selectively exposed to ultraviolet rays and cured, the unexposed areas are immersed in, for example, warm water to be dissolved and removed. Next, the base of this color filter is impregnated with a dye solution of a first color, for example, red, and
The exposed area is dyed to form a red filter component.

Then, in order to isolate this red filter component, the entire light-receiving surface containing this red filter component is coated with, for example, a polyvinyl cinnamate system (e.g.
TPR, KPR, etc.) Cyclized rubber-based (e.g.
Forms a photoresist film such as KTFR, OMR, etc. In order to form a filter component of a second color, for example green, on this photoresist film, a photoresist film is formed only on the light receiving portion in the same manner as described above. This photoresist film is processed in the same manner as described above to form a green filter component. A photoresist film is again formed over the entire light-receiving surface to isolate the green filter component. Next, in order to form a filter component of a third color, for example, blue, the same process as above is performed to form a blue filter component.

The color filter formed as above is
In particular, since the photosensitive aqueous protein solution used as the material is made to have a high viscosity through forced oxidation, the desired viscosity can be achieved in approximately 1 to 3 hours from the start of forced oxidation of the protein aqueous solution. A coating film having a uniform thickness can be obtained. On the other hand, if you do not perform such forced oxidation and only use natural oxidation by leaving it at room temperature, it will take about 20 minutes to achieve similar results.
It will take more time. Therefore, the present invention is extremely advantageous in practice.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 5 c.c. of casein aqueous solution containing ammonium dichromate obtained by stirring in air for 1 hour was placed on a wafer and spinner coated at 1000 rpm for 20 seconds in the first stage and at 2000 rpm in the second stage.
This was carried out for 10 seconds to obtain a photoresist film of approximately 1.5 μm. This photoresist film was processed in a conventional manner as described above to obtain a desired color filter.

Claims (1)

[Claims] 1 A photosensitive composition for a color filter consisting of a protein and a photosensitizer is forcibly oxidized in the presence of an oxygen-containing gas to make it highly viscous and stabilized, and then applied to the substrate of a color filter to form a uniform film. A method for producing a color filter, comprising forming a thick base coating film, and then dyeing the base coating film.