Method for forming a shallow trench isolation structure

摘要

A STI process for a semiconductor device includes the steps of depositing a SiOxCy film where x<2 in a trench by using a biased high-density-plasma-enhanced CVD system, and heat treating the SiOxCy film in an oxidizing ambient to remove carbon and voids therein to form a stoichiometric SiO2 film without causing volume expansion. The depositing step uses a higher ratio of deposited film/sputter-etched film for avoiding plasma damages to the silicon substrate.