Process for etching silicon wafers

摘要

A semiconductor wafer etching process uses an etchant mixture which is formed by mixing nitric and hydrofluoric acids and optionally a surface active agent and which is subsequently topped up with hydrofluoric acid and optionally nitric acid. The novelty is that the etchant mixture is formed by mixing either ≥ 70 wt.% nitric acid and greater than 50 wt.% hydrofluoric acid or greater than 70 wt.% nitric acid and ≥ 50 wt.% hydrofluoric acid, preferably 73-98 wt.% nitric acid and greater than 60 to 95 wt.% hydrofluoric acid. The or each topping-up acid may have the same concentration or a 5-10% higher concentration than the corresponding acid used to form the mixture.