| 摘要 |
PROBLEM TO BE SOLVED: To provide a wet etching system in which etching can be carried out while prolonging the lifetime of etching liquid by controlling the concentration of Si ions in the etching liquid to a constant level and sustaining the etching selectively of an Si<SB>3</SB>N<SB>4</SB>film and an SiO<SB>2</SB>film at a constant level, by depositing SiO<SB>2</SB>in the etching liquid forcibly while taking out a part thereof from an etching liquid pressure circulation passage during an etching process and collecting the deposited SiO<SB>2</SB>. SOLUTION: In the wet etching system where a semiconductor material W on which an Si<SB>3</SB>N<SB>4</SB>film and an SiO<SB>2</SB>film are formed is immersed into high temperature etching liquid M of phosphoric acid in an etching tank 1 and the Si<SB>3</SB>N<SB>4</SB>film is removed selectively by etching, an air vent passage 6 is branched from the way of a passage 2 for pressure circulating the etching liquid M in the etching tank 1 toward the etching tank 1. The air vent passage 6 is coupled with a unit 7 for collecting and removing SiO<SB>2</SB>produced in the etching liquid M while being deposited forcibly by means of cold water or air cooling and oxidation. Consequently, the etching liquid M can be purified by removing SiO<SB>2</SB>during the etching process. COPYRIGHT: (C)2003,JPO
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