| 摘要 |
PROBLEM TO BE SOLVED: To provide a method which enables etching with a high etch selectivity when selectively etching a silicon nitride film formed on the surface of a substrate with respect to a silicon oxide film and does not call for a high performance and a strict control of the equipment. SOLUTION: A heated phosphoric acid aqueous solution 14 is stored in a treatment bath 10, and then the substrate W is dipped in the phosphoric acid aqueous solution 14 to selectively etch the silicon nitride film formed on the surface of the substrate with respect to the silicon oxide film. In this case, a hexafluorosilicic acid aqueous solution is added to the phosphoric acid aqueous solution 14 stored in the treatment bath 10, thus letting the phosphoric acid aqueous solution 14 contain a silicon component and a fluorine component. COPYRIGHT: (C)2008,JPO&INPIT
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