JPH063802B2 - Semiconductor substrate surface protective agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface protective agent for a semiconductor substrate, and more particularly to a protective agent for protecting the substrate surface when the back surface of a wafer is smoothed.

"Prior Art" In a semiconductor substrate manufacturing process, a method of mechanically polishing or chemically etching is used to smooth the back surface of a wafer. In order to protect the pattern formed on the surface of the semiconductor substrate in this step, a method of applying a negative resist to the surface, attaching an adhesive tape, or a method of using both in combination is used. However, it is difficult to remove the protective agent after smoothing the back surface, and highly toxic chemicals are used.

In recent years, treatment methods with higher safety have been demanded from the viewpoints of wastewater pollution, air pollution labor safety, etc. From this viewpoint, some novolac type phenol resins have been put to practical use.

Novolak type phenolic resin has many advantages such as being able to be removed with milder chemicals and being able to be stripped with the same stripping solution as the positive type resist, but using an etchant with a high concentration of hydrofluoric acid will strip the film during etching. No protective agent has been found that can easily withstand this condition.

"Problems to be Solved by the Present Invention" The present invention protects a substrate surface against a strong etching agent for smoothing the back surface of a semiconductor substrate and a mechanical force,
Another object of the present invention is to provide an improved protective agent that can be removed with a low-toxic stripping solution common to positive resists.

"Means for Solving Problems" The present invention has been achieved by forming a protective film from a solution of a phenol-formaldehyde resin having at least one dibenzyl ether bond in one molecule dissolved in a suitable solvent. . Phenol-formaldehyde resin is a polycondensation product obtained by synthesizing phenol and formaldehyde using an acidic or basic catalyst, and the production method and the like are described in Large Organic Chemistry, Volume 23, Synthetic Polymer Compound II (1
985, 5, 15 published by Asakura Shoten).

Alkyl-substituted compounds such as cresol, xylenol, tertiary-butylphenol, nonylphenol and the like are also useful as the phenol. The position of the alkyl group with respect to the —OH group may be any of the ortho, meta and para positions. Halogen substitution products such as chloro, bromo, and fluorine are also known, and these substitution products are also useful. The substituents may be combined or may be a copolycondensate in which phenols having different substituents are combined. At least one dibenzyl ether group is necessary in one molecule, but preferably 0.2 mol or more per 1 mol of phenol.

The solvent is not particularly limited. Appropriately selected from the wettability of the solution when applied with a spinner, spreading, surface quality, etc., but typical ones are the following solvents,
These can be used alone or in combination. The main solvent is glycol ether-based methyl cellosolve,
Ethyl cellosolve, propyl cellosolve, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether and its acetate system, that is, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether Acetate, propylene glycol propyl ether acetate and the like are useful. Amyl acetate, butyl acetate, propyl acetate, and ethyl acetate are used for the acetate type, and methyl isobutyl ketone, methyl ethyl ketone, acetone, cyclohexanone are used for the ketone type, and amyl alcohol, butyl alcohol, propyl alcohol, ethyl alcohol, and methyl are used for the alcohol type. Dimethylformamide, dimethylsulfoxide, etc. are useful as alcohol, diacetone alcohol, and others, and each alkyl group may be a straight chain or branched isomer.

This resist may be added with a surfactant for improving the coating property, and for improving the adhesion, an adhesion aid such as vinyltris (beta-methoxyethoxy) silane, vinyltriethoxysilane, Vinyltrimethoxysilane, gamma- (methacryloxypropyl) trimethoxysilane, beta- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, N-beta- (aminoethyl) gamma-amino Propyltrimethoxysilane, N-beta (aminoethyl) gamma-aminopropylmethyldimethoxysilane, N-phenyl-gamma-aminopropyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-chloropropyltrimethoxy It may be added, such as orchids.

Further, a dye or a pigment may be added for the purpose of coloring.

The protective agent of the present invention is generally used by containing the resin of the present invention in an organic solvent in an amount of 10 to 65% by weight, preferably 20 to 50% by weight.

"Effects of the Invention" According to the present invention, even if an etching agent having a high hydrofluoric acid concentration and a strong etching power is used, there is no occurrence of cracking or peeling during the etching process, In the film peeling process, a film peeling liquid having high labor safety and easy waste liquid treatment (for example, the film peeling liquid M manufactured by Fuji Hunt Co., Ltd.)
Since S-2001) can be used, its industrial effect is extremely remarkable.

"Examples of the Invention" Examples PR-516 was formed on the surface of a patterned silicon wafer by a conventional method such as developing, rinsing, and etching of a resist film.
A 40% ethyl cellosolve acetate solution of 70 (cresol-formaldehyde resin having a dibenzyl ether bond, manufactured by Sumitomo Durize Co., Ltd.) was spinner-coated at 1
Apply at 500 rpm, dry and then 160 in oven
It was baked at ° C for 10 minutes to form a protective film. After cooling, 1 L of hydrofluoric acid aqueous solution (50%) and nitric acid aqueous solution (61%)
It was immersed in an etching solution of 20 L, etched for 3 minutes, washed with water and dried. The protective film was not damaged at all. After that, the protective film could be easily peeled off by a treatment of 100 ° C. for 5 minutes using the peeling liquid MS-2001 (manufactured by Fuji Hunt Co., Ltd.).

Comparative Example By the same method as in Example, a solution of PR-50904 (manufactured by Sumitomo Durize Co., Ltd., novolac type cresol-formaldehyde resin) in ethylcellosolve acetate was applied, and the same treatment was performed. The protective film was cracked on the entire surface during the etching, and more than half was peeled off in the washing step.

Claims (1)

[Claims] 1. A semiconductor substrate surface protective agent used for protecting the surface of a semiconductor substrate after pattern formation is composed of a phenol-formaldehyde resin having at least one dibenzyl ether bond in one molecule. Semiconductor substrate surface protective agent.