| 摘要 |
PROBLEM TO BE SOLVED: To provide a material, which melts rapidly in an etching liquid and suppresses the generation bubbles even though a material that turns into gas is generated in large quantities locally in the vicinities of the reaction surfaces of porous bodies, by a method wherein, when the porous bodies are etched in the etching liquid, the etching is performed on the porous bodies while the etching liquid is subjected to deaeration treatment. SOLUTION: An etching liquid 113 is filled in an etching treatment tank 101 and wafers 104 having a porous layer on the surfaces thereof are put in this liquid 113 and are subjected to porous etching treatment. The liquid 113 overflows from the tank 101 to flow in an overflow tank 102 and is again fed from the tank 102 into the tank 101 by a pump 109 for circulation through a circulating line 108. At this time, a deaerator 110 is arranged in the middle of the line 108 and dissolved gas in the liquid 113 is removed to perform a deaeration treatment on the wafers 104. As a result, an increase in the efficiency of an etching of the wafers 104 and an increase in the uniformity of the etching become possible.
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