JPH04325599A - Sulfuric acid composition having low surface tension - Google Patents

Abstract

PURPOSE:To provide a sulfuric acid compsn. having a low surface tension and being suitable as a sulfuric acid for use in the semiconductor-fabricating step. CONSTITUTION:The title compsn. comprises a fluoroalkylsulfonamide of formula R<1>-SO2-NR<2>-CH2-CHOR<3>-CH2 OR<4> wherein R<1> is a fluoroalkyl group; R<2> is a 1-6C alkyl group; R<3> and R<4> may be the same or different each other and are each a hydrogen atom or a sulfo group and sulfuric acid.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sulfuric acid composition, and particularly to a sulfuric acid composition useful as a cleaning agent in semiconductor manufacturing processes.

0002

[Prior Art] In recent years, microfabrication technology represented by integrated circuits has been increasingly improving its processing accuracy. Taking dynamic random access memory (DRAM) as an example,
Currently, submicron processing technology has been established as a mass production level technology. In microfabrication technology, particles present on a wafer have a significant effect on processing accuracy, and in each process such as photolithography, it is customary to use a cleaning agent such as sulfuric acid to remove particles on the wafer. As the degree of integration of the above-mentioned integrated circuits increases, patterns become finer, irregularities become more complex, etc., and the removal of particles required in the cleaning process is also becoming more demanding.

[0003] Sulfuric acid is used alone or in combination with other substances for cleaning silicon substrates, removing resist films, etc. in semiconductor manufacturing processes. However, when conventional high-purity sulfuric acid is used, it has a large surface tension and poor wettability, which makes it difficult for the cleaning agent to penetrate between fine patterns, resulting in insufficient cleaning. Japanese Patent Publication No. 2-2402
No. 85 teaches a low surface tension sulfuric acid composition in which a fluorosurfactant is added to sulfuric acid.

0004

SUMMARY OF THE INVENTION In view of the above background, an object of the present invention is to provide a sulfuric acid composition that has low surface tension and good wettability.

[0005]

[Means for Solving the Problems] In order to solve these problems, as a result of various studies, we discovered that the purpose could be achieved by using a specific fluorine-based surfactant, and developed the present invention. completed. That is, the gist of the present invention is the general formula R1 -SO2 -NR2 -CH2 -CHOR
3 -CH2OR4 (1) (in the formula, R1 represents a fluoroalkyl group, R2 has a carbon number of 1
-6 alkyl groups, and R3 and R4 may be the same or different and represent a hydrogen atom or a sulfo group. )
A sulfuric acid composition having a low surface tension is obtained by blending a fluoroalkylsulfonamide compound represented by the following with sulfuric acid.

The present invention will be explained below. The above general formula (1
), the fluoroalkyl group represented by R1 is usually an alkyl group having 3 or more carbon atoms, preferably 5 to 20 carbon atoms, in which a portion of the hydrogen atoms are substituted with fluorine atoms, and the substitution rate is preferably 50% or more. is 80% or more. R
Examples of the alkyl group represented by 2 include methyl, ethyl, linear or branched propyl, butyl, pentyl,
It is an alkyl group having 1 to 6 carbon atoms such as hexyl, and an alkyl group having 2 to 5 carbon atoms is particularly preferable.

In the low surface tension sulfuric acid composition of the present invention, it is essential to add and dissolve an appropriate amount of the fluoroalkylsulfonamide compound represented by the above general formula (1), and the amount added is as follows: 0.00 for sulfuric acid
The amount is 1 to 0.1% by weight, and the more preferable amount is 0.0% by weight.
05 to 0.05% by weight. If the amount added is too small, the effect will not be sufficient, and if it is too large, no further effect will be obtained and it is meaningless.

[0008] Furthermore, if the sulfuric acid (aqueous solution) added is too dilute, the cleaning effect will not be sufficient, so generally 60% by weight or more, preferably 70% by weight or more is used. The fluoroalkylsulfonamide compound used in the present invention is sufficiently stable even in sulfuric acid at the above-mentioned high concentration and/or high temperature, and fully exhibits its effects. In addition, sulfuric acid is sometimes used for cleaning by mixing with hydrogen peroxide solution, but the fluoroalkylsulfonamide compound used in the present invention is stable even in such a strongly oxidizing atmosphere, and can be used at high temperatures. The effect is fully demonstrated even at the bottom. Since the sulfuric acid composition of the present invention is primarily intended for use in semiconductor manufacturing processes, it is necessary to use highly purified raw materials, sulfuric acid and sulfonamide.

[0009]

EXAMPLES Next, the present invention will be explained in more detail with reference to specific examples, but the present invention is not limited in any way by the examples unless the gist of the invention is exceeded. Examples 1 to 4 and Comparative Examples 1 to 2 A predetermined amount of the sulfonamide listed in Table 1 was added to 89% sulfuric acid, and the surface tension at 22°C was measured by the Wilhelmi method. In addition, for comparison, the surface tension was similarly measured when no sulfonamide was added (Comparative Example 1) and when a sulfonamide of the following formula (A) having a similar structure to the sulfonamide used in the present invention was used (Comparative Example 2). was measured. The results are shown in Table-1.

Comparative Example Sulfonamide C8 H17SO2 N(C3 H7)-(
CH2 CH2 O)20H (A)

[
0011

[Table 1] Example-5 A mixed composition obtained by mixing the sulfuric acid composition used in Example-2 and 30% by weight hydrogen peroxide solution at a ratio of 4:1 (volume ratio) is shown in Table-2. The surface tension of the composition was measured at 22° C. after being heated and maintained for a period of time and sampled over time. The results are shown in Table-2.

0012

[Table 2]

[0013]

According to the present invention, it is possible to provide a sulfuric acid composition that has a low surface tension and is stable even in a highly oxidizing atmosphere and at high temperatures, which is highly advantageous in the industrial production of highly integrated circuits.

Claims (1)

[Claims] [Claim 1] General formula R1 -SO2 -NR2 -CH2 -CHOR
3 -CH2OR4 (1) (wherein, R1 represents a fluoroalkyl group, R2 represents an alkyl group having 1 to 6 carbon atoms, and R3 and R4 may be the same or different and represent a hydrogen atom or a sulfo group. )
A sulfuric acid composition having a low surface tension obtained by blending a fluoroalkylsulfonamide compound represented by sulfuric acid with sulfuric acid.