Fin field-effect transistor device and method of forming the same

Abstract

A method of forming a semiconductor device includes forming a first dummy gate structure and a second dummy gate structure over a fin protruding above a substrate, where the first dummy gate structure and the second dummy gate structure are surrounded by a dielectric layer; and replacing the first dummy gate structure and the second dummy gate structure with a first metal gate and a second metal gate, respectively, where the replacing includes: removing the first and the second dummy gate structures to form a first recess and a second recess in the dielectric layer, respectively; forming a gate dielectric layer in the first recess and in the second recess; forming an N-type work function layer and a capping layer successively over the gate dielectric layer in the second recess but not in the first recess; and filling the first recess and the second recess with an electrically conductive material.