METHODS OF FABRICATING SEMICONDUCTOR DEVICES WITH DIFFERENTIALLY NITRIDED GATE INSULATORS

摘要

An insulation layer is formed on a substrate having an NMOS region and a PMOS region defined therein. A first conductive layer is formed on the insulation layer in the PMOS region, leaving a portion of the insulation layer in the NMOS region exposed. Nitriding is performed to produce a first nitrogen concentration in the insulation layer in the NMOS region and a second nitrogen concentration less than the first nitrogen concentration in the insulation layer in the PMOS region. A second conductive layer is formed on the insulation layer and the first conductive layer and the first and second conductive layers and the insulation layer are patterned to form a first gate structure and a second gate structure in the NMOS region and the PMOS region, respectively.