WIDE MARGIN CMP FOR STI

The challenge in integrating oxide CMP for shallow trench isolation is to expose silicon nitride completely across all active regions, with minimal nitride loss and oxide dishing. Device patterns strongly influ ence the CMP process. Proper CMP tool settings minimize pattern depend ence and trench dishing as a function of overpolish, and a high select ivity slurry minimizes nitride loss. The combination of these two resu lts in a CMP process with a large process window.