US Patent 7632729 Method for semiconductor device performance enhancement

A method of manufacturing a semiconductor device is disclosed. The method provides a semiconductor substrate with at least a PMOS device and at least an NMOS device thereon. A first insulating layer is formed overlying the NMOS and PMOS devices. A second insulating layer is formed overlying the first insulating layer. The second insulating layer overlying the PMOS device is thinned to leave portion of the second insulating layer. A first thermal treatment is performed on the NMOS and PMOS devices. The second insulating layer overlying the NMOS device and the remaining portion of the second insulating layer overlying the PMOS device are removed and the first insulating layer overlying the NMOS and PMOS devices is thinned to leave a remaining portion thereof.