| 摘要 |
The present invention provides a regeneration process of the etching solution for the silicon nitride film, applying phosphoric acid aqueous solution, wherein multiple numbers of filters are connected to the piping path of etching solution extracted from the etching tank by switching alternately in parallel or in series; in both cases that said multiple numbers of filters are connected in parallel or in series, said extracted etching solution being supplied to a filter with a filter element of a high silicon removal rate of silicon compounds with already deposited silicon compounds, thus maintaining a high silicon removal rate of silicon compounds.
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