METHOD FOR SELECTIVELY ETCHING SILICON USING WET ETCH

摘要

PURPOSE: A selective etch method of silicon is provided to perform a wet etch having a good etch selectivity between a doped silicon thin film and an undoped silicon thin film. CONSTITUTION: An undoped silicon thin film(22) and a doped silicon thin film(23) are stacked on a defined process completed structure(21). Then, a mask pattern(24) is formed by selectively etching a photoresist or a metal having a wet etch selectivity with a polysilicon. Then, the doped silicon thin film(23) is selectively removed by a wet etching using the mask pattern(24). At this time, the wet etching is performed using a mixed solution made of HF, a nitric acid and an acetic acid or another mixed solution made of the HF, the nit acid and water. The mixed solution oxidizes a silicon thin film using the nitric acid and simultaneously etches an oxide using the HF.