The present disclosure provides a method is provided for fabricating a metal oxide semiconductor (MOS) gate stack on a semiconductor substrate. The method includes generating moisture on a surface of the semiconductor substrate to form an oxide layer less than 10 nanometers thin and performing a nitridation process on the thin oxide layer. After the nitridation process, the method includes performing a polysilicon deposition process on the surface of the semiconductor substrate, doping the polysilicon deposition to a level of 5×1015 at/cm3, and cleaning the doped polysilicon with a light ammonia solution.