Patent ID: 9748358
Date: 2017-08-29
CPC Classifications: H01L

Claim:
1. A method for fabricating a semiconductor device, the method comprising: forming a replacement gate structure on a semiconductor layer of a substrate, the replacement gate structure at least comprising a polysilicon layer; after forming the replacement gate structure, forming a gate spacer on the replacement gate structure; implanting atoms in an upper portion of the polysilicon layer, the implanting expanding the upper portion of the polysilicon layer and a corresponding upper portion of the gate spacer in at least a lateral direction beyond a lower portion of the polysilicon layer and a lower portion of the gate spacer, respectively; after the implanting, removing the polysilicon layer to form a gate cavity surrounded by the gate spacer; and forming a metal gate stack within the gate cavity and in contact with sidewalls of the gate spacer, the metal gate stack comprising a upper portion having a width that is greater than a width of a lower portion of the metal gate stack.