DAMASCENE REPLACEMENT METAL GATE PROCESS WITH CONTROLLED GATE PROFILE AND LENGTH USING Si1-xGex AS SACRIFICIAL MATERIAL
A method of forming a metal gate in a wafer. PolySi 1-x Ge x and polysilicon are used to form a tapered groove. Gate oxide, PolySi 1-x Ge x , and polysilicon is deposited on a wafer. A resist pattern is formed. A portion of the polysilicon, PolySi 1-x Ge x , and gate oxide is removed to provide a tapered profile. The resist is removed; a dielectric liner is deposited, and then at least a portion of the dielectric liner is removed, thereby exposing the polysilicon and leaving the dielectric liner in contact with the polysilicon, PolySi 1-x Ge x , and gate oxide. A dielectric is deposited, and a portion is removed thereby exposing the polysilicon. The polysilicon, PolySi 1-x Ge x , and gate oxide is removed from inside the dielectric liner, thereby leaving a tapered gate groove. Metal is then deposited in the groove.
1 . A metal gate in a wafer comprising: a groove which has a tapered profile which converges from an opening to a base; metal in the groove, thereby providing said metal gate.
2 . A metal gate as recited in claim 1 , further comprising a dielectric liner on a side of said groove.
3 . A metal gate as recited in claim 2 , further comprising a dielectric layer, said dielectric liner being disposed between said dielectric layer and said metal.