Patent ID: 7276417
Filing Date: 2007-10-02
Classification: H01L

Abstract:
1. A method for forming a semiconductor structure, the method comprising: providing a semiconductor substrate including an NMOS device region and a PMOS device region; forming a hard mask layer over the semiconductor substrate; forming and patterning a photo resist over the hard mask layer; etching the hard mask layer and the semiconductor substrate to form trenches, wherein the trenches define a first active region in the NMOS device region and a second active region in the PMOS device region; filling the trenches with a high-shrinkage dielectric material; performing a chemical mechanical polish (CMP) to the high-shrinkage dielectric material; forming a mask over the high-shrinkage dielectric material in the NMOS device region, wherein the mask does not extend over the PMOS device region, and wherein the step of forming the mask is performed after the step of performing the CMP; performing a re-oxidization to the semiconductor substrate after the step of forming the mask; performing a densification anneal to the semiconductor substrate after the step of forming the mask, so that the high-shrinkage dielectric material substantially shrinks; removing the mask; performing a chemical mechanical polish (CMP); and removing the hard mask layer.