Silicon substrate isolation trenches etching method for use during manufacturing of DRAM cells, involves aligning etching gas components such that etching depth at two different sized upper surface sections of substrate has same size

摘要

The method involves opening a mask on an upper surface of a silicon substrate. Uncovered surface sections are exposed to etching gas having etching gas components etching silicon, passive gas components passivating the silicon and the etching gas components etching a passivation section. The components are aligned one over other such that etching depth at two different sized upper surface sections has same/approximately same size. The etching gas component etching the silicon is a gas mixture containing silicon chloride and silicon fluoride. The etching gas component etching a passivation section is a gas mixture containing methane, gas mixture containing tri fluoro methane, gas mixture containing nitrogen fluoride and gas mixture containing sulphur hexa fluoride.