| 摘要 |
PROBLEM TO BE SOLVED: To provide a mixed acid liquid in etching which is suitably used for planarizing a semiconductor wafer or improving its glossiness required for the wafer. SOLUTION: The mixed acid liquid contains hydrofluoric acid, phosphoric acid, nitric acid and fluorophosphoric acid and has a fluorophosphoric acid concentration of 3-15 wt.%. In a preferred embodiment, the hydrofluoric acid concentration is 5-12 wt.%, the phosphoric acid concentration is 15-40 wt.% and the nitric acid concentration is 25-40 wt.%.
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