Method to improve reliability of replacement gate device

1. A method of fabricating a gate stack for a FinFET device, said method comprising steps of:

after removal of a dummy gate, providing a replacement gate structure by performing steps of:

growing a high-k dielectric layer over an area vacated by the dummy gate;

depositing a thin metal layer over the high-k dielectric layer;

depositing a sacrificial layer over the thin metal layer;

annealing the replacement gate structure comprising the high-k dielectric layer, thin metal layer, and sacrificial layer at a high temperature of not less than 800° C.;

performing a millisecond anneal;

removing the sacrificial layer; and

depositing a metal layer of low resistivity metal.

2. The method of claim 1 wherein performing the millisecond anneal comprises performing a millisecond anneal with a flash lamp.

3. The method of claim 1 wherein annealing the structure comprises performing a rapid thermal anneal at a temperature between 800° C. and 1100° C., inclusive, in ambient nitrogen.