Patent ID: 7833855

Claim:
A method of forming a field effect transistor, comprising the steps of: forming a gate insulating layer on a semiconductor substrate comprising a P-MOS transistor region and an N-MOS transistor region; forming a metal nitride layer on the gate insulating layer by exposing the gate insulating layer to a tantalum amine derivative comprising Ta(NR 1 )(NR 2 NR 3 ) 3 , wherein R 1 , R 2 and R 3 are each independently selected from the group consisting of H and C 1 -C 6 alkyl; and implanting nitrogen into the metal nitride layer, wherein the implanting step comprises selectively implanting nitrogen into a first portion of the metal nitride layer in the P-MOS transistor region, but not into a second portion of the metal nitride layer in the N-MOS transistor region.