JPS5931029A - Etchant for silicon resin film - Google Patents

Abstract

PURPOSE:To etch in a short time easily and moreover uniformly the silicon resin film by a method wherein the etchant is prepared of hydrofluoric acid, ammonium fluoride and a surfactant. CONSTITUTION:The etchant for the silicon resin film contains ammonium fluoride and the surfactant together with hydrofluoric acid. Hydrofluoric acid contained in the etchant is the component to participate directly in etching of the silicon resin film, and it is desirable to make to be contained as hydrogen fluoride in the etchant at concentration of the degree of 2-10wt%. As the surfactant, any matter able to reduce surface tension of water is favorable. It is desirable to make ammonium fluoride to be contained in the extent of 4-40pts. wt. per 1pts.wt. of hydrofluoric acid aqueous solution, and moreover it is desirable to make the surface-active agent to be contained in the extent of 0.004- 40pts.wt. normally although it depends upon the kind thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an etching solution for silicone coatings, and more particularly to a practically excellent etching solution that can easily and uniformly etch silicone resin coatings in a short period of time.

In recent years, with the remarkable development of electronic materials, heat-resistant coatings have become necessary as element constituent materials such as interlayer insulating films or passivation films in multilayer wiring such as semiconductors, especially ICs, and LSIs. An example of a material that meets your needs is polyimide.

Nitrogen-containing resins and silicone resins such as polyquinoxaline, polyisoindoquinazolinedione, and polytriazine are preferred electronic materials because they have excellent heat resistance and do not contain ions with large electric mobility. Yes, and widely used.

These coatings are usually etched to form the desired pattern. Nitrogen-containing resin coatings can be effectively etched using an aqueous hydrazine solution, and are also used industrially.

On the other hand, for silicone resin coatings which are superior to nitrogen-containing resins, an aqueous solution containing hydrofluoric acid and nitric acid, which has been known as an etching solution for silicon oxide coatings, is used. However, since the silicone resin coating has water repellency, it takes a long time to process with the above-mentioned etching solution, and furthermore, it has the disadvantage that uniform etching cannot be obtained, so it was not an appropriate etching solution. In addition, as another method for etching silicone resin coating,
There is a dry etching method using plasma, but it not only requires sophisticated equipment but also requires a long etching time, so it is not suitable for large-scale production and cannot be used industrially.

The present inventors have developed an etching solution that can easily and uniformly etch a silicone resin coating with excellent insulation and heat resistance, which is extremely useful in the electronics industry, especially in the electronics-related field. As a result of extensive research, we have discovered an industrially satisfactory etching solution containing a combination of three types of components, and have arrived at the present invention.

That is, the present invention provides an etching solution for silicone resin coatings containing hydrofluoric acid, ammonium fluoride, and a surfactant.

In the present invention, the silicone resin forming the film to be etched includes silicone resins known as film-forming materials in the electronics technology field.
In particular, heat-resistant silicone resins, such as silicone ladder polymer (RS103//2)n, or -R8iOV2- or -RR' EIiO- [in the formula, R
and R' represents an alkyl group, an aryl group, or a substituted aryl group.

The fluorine arsenic acid contained in the etching solution of the present invention is
A component directly involved in the etching of silicone resin coatings, with a concentration of 2 to 10% hydrogen fluoride in the etching solution.
It is preferable to contain it at a concentration of approximately the weight ratio. Hydrofluoric acid is usually available as an aqueous solution containing 25 to 505 to 50 parts by weight of hydrogen.

The etching solution of the present invention must contain ammonium fluoride and a surfactant as well as hydrofluoric acid. The surfactant used in the etching solution of the present invention may be one that lowers the surface tension of water, such as m-alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, ethylene glycol, and glycerin. , diethylene glycol,
polyhydric alcohols and their ethers, such as triethylene glycol, phlopylene glycol, dipropylene glycol, monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol dibutyl ether;
Esters such as methyl acetate, ethyl acetate, propyl acetate, acetone, diacetone alcohol, ketones such as methyl ethyl ketone, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkylphenyl ether, polyhydric alcohol Nonionic surfactants such as fatty acid ester, polyoxyethylene polyhydric alcohol fatty acid ester, sucrose fatty acid ester, cationic surfactants such as halogenated trimethylaminoethyl alkylamide, alkylpyridinium sulfate, halogenated alkyltrimethylammonium, etc. These may be used alone or in combination of two or more.

It is preferable that the etching solution of the present invention contains ammonium fluoride in the range of 4 to 40 parts by weight per 1 part by weight of the aqueous hydrofluoric acid solution, and the surfactant may also include, depending on the type of surfactant, It is usually preferable to contain it in a range of 0.004 to 40 parts by weight.

Further preferred contents of each are 4 to 20 parts by weight and 0.4 to 32 parts by weight. If the content of ammonium fluoride or surfactant is too high or too low, the etching rate will be slow, which is not desirable industrially.

When the etching aqueous solution prepared under the above-mentioned compositional conditions comes into contact with the silicone resin coating, it uniformly etches it in a short period of time, and the desired etching can be easily obtained. Usually, the heat-resistant silicone resin coating is made of a liquid containing a condensable silicone oligomer, for example,
It is formed by heating at a temperature of 00°C and curing it, but the higher the heating temperature and the longer the heating time, the higher the water repellency. Although the phenomenon of uniform etching being formed is unavoidable, the use of the etching solution of the present invention makes it possible to extremely effectively etch even such highly water-repellent films. , it is possible to perform the desired uniform etching in a short time.

The etching solution of the present invention can be easily prepared by adding predetermined amounts of ammonium fluoride and a surfactant to an aqueous solution of hydrofluoric acid, ie, fluorine arsenide, and stirring well to homogenize.

Etching is carried out by immersing the object having a silicone resin coating in an etching solution. During the etching process, it is desirable to stir the etching solution, and stirring speeds up the etching speed and achieves uniform etching. be able to. In some cases, the film to be etched can also be etched by being sprayed or coated.

The etching solution of the present invention is a novel etching solution that has the excellent performance that has been conventionally desired as an etching solution for silicone resin coatings, and is suitable for etching highly heat-resistant silicone resin coatings that do not contain alkali metals or other conductive impurities. It is extremely desirable because it can be applied to

Next, the non-invention will be explained in more detail using a specific example. .

Examples 1 to 6, Comparative Examples 1 to 2 Coating liquid QC for forming silicon film! DTypθ-7 (trade name, manufactured by Tokyo Ohka) was applied onto a silicon wafer using a spinner, and the solvent was gradually removed using a pre-bake dryer at 140"C for semi-curing.
It was cured in a kiln maintained at 00°C. An etching mask is formed using a patterned resist on the obtained silicone resin film, and the silicon substrate is immersed in an etching solution having the composition shown in Table 1 for a predetermined time, washed with water, dried, and then coated with a stripping solution. The resist film on the mask was completely removed. Table 1 shows the processing conditions and results.

The organosilicon film subjected to etching in this example is a highly heat-resistant organosilicon film that does not contain interfering impurities such as alkali metals and is useful in the semiconductor field, and is conventionally considered difficult to etch. It is. However, the etching solution of the present invention enables easy and uniform etching in a short period of time, making it easy to use industrially.

From the above results, it has been found that the etching solution containing the three components of the present invention is capable of etching a silicone resin film, which is extremely useful in the electronics field, which has been considered difficult in the past, due to the mutual action of the three components. It can be completed in a short time, about less than a minute.

Furthermore, the etching condition was uniform and a particularly good finish was obtained, indicating that it is highly practical.

Patent applicant: Tokyo Denshi Kagaku Co., Ltd. Agent Akira Agata lO-

Claims (1)

[Claims] 1. An etching liquid for silicone resin coatings containing hydrofluoric acid, ammonium fluoride, and a surfactant. 27% ammonium per 1 part by weight of hydrofluoric acid
The etching solution according to claim 1, containing up to 40 parts by weight. 3 Surfactant at 0.00% per 1 part by weight of hydrofluoric acid
Claim 1 or 2 containing 4 to 40 parts by weight
Etching liquid described in section.