Method of lateral oxidation of NFET and PFET high-K gate stacks
View Patent ↗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:
obtaining a semiconductor structure having a first gate stack and a second gate stack, each containing material layers that include a high-k dielectric layer, the first gate stack including a work-function conductor layer, and the second gate stack including a work-function conductor layer;
oxidizing in a lateral manner (i) the high-k dielectric layer of the first gate stack, such that an oxygen content of the high-k dielectric layer of the first gate stack increases first at sidewalls of the high-k dielectric layer of the first gate stack, and (ii) the high-k dielectric layer of the second gate stack, such that an oxygen content of the high-k dielectric layer of the second gate stack increases first at sidewalls of the high-k dielectric layer of the second gate stack; and
fabricating (i) a n-type field effect transistor from the first gate stack after laterally oxidizing at least the high-k dielectric layer of the first gate stack, and (ii) a p-type field effect transistor from the second gate stack after laterally oxidizing at least the high-k dielectric layer of the second gate stack;
wherein the oxidizing comprises:
oxidizing in a lateral manner the work-function conductor layer of the first gate stack, such that oxygen content increases first near sidewalls of the work-function conductor layer of the first gate stack; and
oxidizing in a lateral manner the work-function conductor layer of the second gate stack, such that oxygen content increases first near sidewalls of the work-function conductor layer of the second gate stack.
2. The method of claim 1 , wherein the high-k dielectric layer of the first gate stack and the high-k dielectric layer of the second gate stack are comprised of the same selection of dielectric material.
3. The method of claim 1 , wherein the high-k dielectric layer of the first gate stack and the high-k dielectric layer of the second gate stack are not comprised of the same selection of dielectric material.
4. The method of claim 1 , wherein the oxidizing further comprises achieving complete lateral oxidation of the high-k dielectric layer of the first gate stack, such that oxygen diffuses to the center of the high-k dielectric layer of the first gate stack; and
achieving complete lateral oxidation of the high-k dielectric layer of the second gate stack, such that oxygen diffuses to the center of the high-k dielectric layer of the second gate stack.
5. The method of claim 1 , wherein the oxidizing further comprises achieving partial lateral oxidation of the high-k dielectric layer of the first gate stack, such that oxygen does not diffuse to the center of the high-k dielectric layer of the first gate stack; and
achieving complete lateral oxidation of the high-k dielectric layer of the second gate stack, such that oxygen diffuses to the center of the high-k dielectric layer of the second gate stack.
6. The method of claim 1 , wherein the oxidizing further comprises achieving complete lateral oxidation of the high-k dielectric layer of the first gate stack, such that oxygen diffuses to the center of the high-k dielectric layer of the first gate stack; and
achieving partial lateral oxidation of the high-k dielectric layer of the second gate stack, such that oxygen does not diffuse to the center of the high-k dielectric layer of the second gate stack.
7. The method of claim 1 , wherein the oxidizing further comprises achieving partial lateral oxidation of the high-k dielectric layer of the first gate stack, such that oxygen does not diffuse to the center of the high-k dielectric layer of the first gate stack; and
achieving partial lateral oxidation of the high-k dielectric layer of the second gate stack, such that oxygen does not diffuse to the center of the high-k dielectric layer of the second gate stack.
8. The method of claim 1 , wherein:
the work-function conductor layer of the first gate stack and the work-function conductor layer of the second gate stack are of the same work-function conductor material; and
the high-k dielectric layer of the first gate stack and the high-k dielectric layer of the second gate stack are of the same selection of dielectric material.
9. The method of claim 1 , wherein:
the work-function conductor layer of the first gate stack and the work-function conductor layer of the second gate stack are of the same work-function conductor material; and
the high-k dielectric layer of the first gate stack and the high-k dielectric layer of the second gate stack are not of the same selection of dielectric material.
10. The method of claim 1 , wherein:
the work-function conductor layer of the first gate stack and the work-function conductor layer of the second gate stack are not of the same work-function conductor material, and
the high-k dielectric layer of the first gate stack and the high-k dielectric layer of the second gate stack are of the same selection of dielectric material.
11. The method of claim 1 , wherein:
the work-function conductor layer of the first gate stack and the work-function conductor layer of the second gate stack are not of the same work-function conductor material; and
the high-k dielectric layer of the first gate stack and the high-k dielectric layer of the second gate stack are not of the same selection of dielectric material.