Method of lateral oxidation of NFET and PFET high-k gate stacks
A method for fabricating a semiconductor circuit includes obtaining a semiconductor structure having a gate stack of material layers including a high-k dielectric layer; oxidizing in a lateral manner the high-k dielectric layer, such that oxygen content of the high-k dielectric layer is increased first at the sidewalls of the high-k dielectric layer; and completing fabrication of a n-type field effect transistor from the gate stack after laterally oxidizing the high-k dielectric layer of the gate stack.
1. A method for fabricating a semiconductor circuit, the method comprising the steps of:
obtaining a semiconductor structure having a gate stack of material layers including a high-k dielectric layer and a work-function conductor layer;
oxidizing in a lateral manner the high-k dielectric layer, such that an oxygen content of the high-k dielectric layer is increased first at sidewalls of the high-k dielectric layer, and oxidizing in a lateral manner the work-function conductor layer of the gate stack, such that an oxygen content of the work-function conductor layer is increased first at sidewalls of the work-function conductor layer; and
completing fabrication of a n-type field effect transistor from the gate stack after laterally oxidizing the high-k dielectric layer of the gate stack.
2. The method of claim 1 , wherein the oxidizing further comprises achieving complete lateral oxidation of the high-k dielectric layer of the gate stack, such that oxygen diffuses to the center of the high-k dielectric layer of the gate stack.
3. The method of claim 1 , wherein the oxidizing further comprises achieving partial lateral oxidation of the high-k dielectric layer of the gate stack, such that oxygen does not diffuse to the center of the high-k dielectric layer of the gate stack.
4. A method for fabricating a semiconductor circuit, the method comprising the steps of:
obtaining a semiconductor structure having a gate stack of material layers including a high-k dielectric layer;
oxidizing in a lateral manner the high-k dielectric layer, such that the oxygen content of the high-k dielectric layer is increased first at the sidewalls of the high-k dielectric layer;
completing fabrication of a n-type field effect transistor from the gate stack after laterally oxidizing the high-k dielectric layer of the gate stack;
removing material from the sidewalls of the gate stack of the semiconductor structure prior to the oxidizing step, such that the sidewalls of the gate stack of the semiconductor structure are exposed; and
fabricating sidewall spacers on the semiconductor structure after the oxidizing step, such that the fabricated sidewall spacers are in contact with the sidewalls of the gate stack.