Patent ID: 8518783

Claim:
A method of forming a gate structure of a field effect transistor, the method comprising: forming a gate stack comprising, in order: a SiO 2 -based layer adjacent a channel region of the field effect transistor; a high-K dielectric layer on the SiO 2 -based layer; and a gate electrode on the high-K dielectric layer; performing an Al introduction step, whereby Al is introduced into the SiO 2 -based layer to form an Al x Si y O z interfacial layer in between the high-K dielectric layer and the channel region; performing a heating step to allow Al introduced into the channel region during said Al introduction step to diffuse out of the channel region into the interfacial layer; and compensating for a p-type tuning effect on the work function of the gate electrode due to the Al introduction step by adding n-type dopants to the gate electrode.