US Patent 7445981 Method for forming a dual metal gate structure

A method includes forming a first gate dielectric layer over a semiconductor layer having a first and a second well region, forming a first metal gate electrode layer over the first gate dielectric, forming a sidewall protection layer over the first metal gate electrode layer and adjacent sidewalls of the first gate dielectric layer and first metal gate electrode layer, forming a channel region layer over the second well region, forming a second gate dielectric layer over the channel region layer, forming a second metal gate electrode layer, and forming a first gate stack including a portion of each of the first gate dielectric layer and first metal gate electrode layer over the first well region and forming a second gate stack including a portion of each of the second gate dielectric layer and second metal gate electrode layer over the channel region layer and over the second well region.