Patent ID: 9698059
Date: 2017-07-04
CPC Classifications: H01L

Claim:
1. A method of forming a semiconductor device, comprising: providing a substrate; forming a dielectric layer on the substrate, wherein the dielectric layer comprises a first gate trench, a second gate trench and a third gate trench formed therein; performing a first threshold voltage implantation process in the first gate trench; performing a third threshold voltage implantation process in the third gate trench; after performing the third threshold voltage implantation process, forming a first work function layer in the first gate trench after the first threshold voltage implantation process; forming a second work function layer in the second gate trench, and on the first work function layer in the first gate trench, wherein the first work function layer and the second work function layer have a same conductive type; and forming a third work function layer in the third gate trench, and on the second work function layer formed in the second gate trench and the first gate trench, wherein the third work function layer has a different conductive type from that of the first work function layer.