An oxynitride pad layer and a masking layer are formed on an ultrathin
semiconductor-on-insulator substrate containing a top semiconductor layer
comprising silicon. A first portion of a shallow trench is patterned in a
top semiconductor layer by lithographic masking of an NFET region and an
etch, in which exposed portions of the buried insulator layer is recessed
and the top semiconductor layer is undercut. A thick thermal silicon
oxide liner is formed on the exposed sidewalls and bottom peripheral
surfaces of a PFET active area to apply a high laterally compressive
stress. A second portion of the shallow trench is formed by lithographic
masking of a PFET region including the PFET active area. A thin thermal
silicon oxide or no thermal silicon oxide is formed on exposed sidewalls
of the NFET active area, which is subjected to a low lateral compressive
stress or no lateral compressive stress.