Abstract: For use with a sub-micron semiconductor process, a trench isolation process improves the etch profile of trenches among dense and isolated lines. In an example embodiment, a process forms a dielectric stack of silicon dioxide, silicon nitride and silicon oxynitride on a silicon substrate. Photolithography and etch define trench regions in the silicon substrate through the dielectric stack. Silicon oxynitride acts as a hard mask reducing differences in the sidewall slope among dense areas of the semiconductor device and the sparse areas of the semiconductor device.

Abstract: A method for preparing a semiconductor substrate for subsequent silicide formation. In one embodiment, the present invention subjects the semiconductor substrate to an ashing environment. In the present embodiment, the ashing environment is comprised of H2O vapor, and a gaseous fluorocarbon or a fluorinated hydrocarbon gas. In so doing, contaminants on the semiconductor substrate are removed. Next, the present invention subjects a mask covering a polysilicon stack to a mask-removal ashing environment. In the present embodiment, the mask-removal ashing environment is comprised of an O2 plasma. In so doing, the mask covering the polysilicon stack is removed. As a result, the semiconductor substrate and the top surface of the polysilicon stack are prepared for subsequent silicide formation thereon.