| 摘要 |
PROBLEM TO BE SOLVED: To provide a refilling method of an etching solution in which the etching of a silicon wafer can continuously be performed with a chemical refilling amount dependent on an etching allowance without degrading etching capability. SOLUTION: After etching a wafer using an etching solution composed of a hydrofluoric acid, a nitric acid, a phosphorous acid, and deionized water, and satisfying a predetermined formula; the etching liquid consumed by single wafer etching is collected before refilling the nitric acid by weight z shown by a formula (6), the phosphorous acid by weight m shown by a formula (7), and the hydrofluoric acid by weight n shown by a formula (8), respectively. z=(Ax/B)+y (6), m=(Dx/B)+[(D-C)y/A] (7), n=Dx/B (8). In the formulas (6)-(8), A, B, C and D represent weights of the nitric acid, deionized water, phosphorous acid, and hydrofluoric acid contained in the etching solution before etching, x represents the weight of water produced by etching, and y represents the weight of the nitric acid consumed by etching. COPYRIGHT: (C)2008,JPO&INPIT
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