Wafer bevel shape inducing high defect density in shallow trench isolation process

The defect density reduction is one of the main challenges to increase the yield. This article presents a mechanism of defect formation specific to the STI module. This defect-flake like - appears during HDP-CVD process deposition. It comes from oxide bubbles localised at the bevel of the substrate. The suppression of this defect consists into the bevel shape optimization. Moreover, process improvement as resist strip post etch contributes to clean the bevel from polymer and reduces strongly the flakes density.