Gas Filtration Method

Abstract

The invention relates to the field of semiconductor preparation and in particular relates to a gas filtering method. Before a PECVD deposition process is performed by utilizing acetylene, acetylene stored in a steel cylinder is subjected to filtering and drying treatment. A phenomenon that other substances in the steel cylinder enter a PECVD machine stand along with the acetylene to be subjected to production so as to cause thickness drift of an amorphous carbon thin film can be effectively avoided.

Description

technical field [0001] The invention relates to the field of semiconductor preparation, in particular to a gas filtering method. Background technique [0002] Amorphous carbon film is a common mask material in integrated circuit manufacturing, and its advantage is that it is compatible with Si, SiO 2 Compared with other materials, it has a high etching selectivity ratio, and can be ashed and easily removed. It is usually formed by PECVD (Plasma Enhanced Chemical Vapor Deposition, plasma enhanced chemical vapor deposition), and the main reaction gas is acetylene (C 2 h 2 ). The reaction formula is: C 2 h 2 →C+H 2 . [0003] Acetylene is easy to decompose under high pressure, and is unstable and will explode. In order to store this dangerous gas stably in steel cylinders, it is necessary to fill the cylinder with a porous substance made of activated carbon, sawdust, pumice and diatomaceous earth. And infiltrate the acetone on the porous material as a solvent, when the ...

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Problems solved by technology

This leads to a very serious problem, that is, with the consumption of acetylene, under the same acetylene flow setting, the thickness of the amorphous carbon film deposited by the PECVD machine will become thinner and thinner, such as figure 1 shown

C 2 h 2 The corresponding thickness when the bottle is full is But under the same process conditions, C 2 h 2 When only 10% is consumed, the corresponding thickness is only In the process of manufacturing integrated circuits, there are precise requirements for the thickness of the film, and it is not allowed for the film thickness to fluctuate so much with the consumption of the gas source.

[0005] In order to minimize the drift of the film thickness, the engineer can adjust the deposition time or the flow setting to solve this problem according to the situation, but this will undoubtedly increase the burden on the engineer, and the decrease in thickness is directly related to the running volume of the machine, making the problem more complicated. more complicated

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