Semiconductor device and manufacturing method thereof

Abstract

A method includes forming a fin structure over a substrate, wherein the fin structure comprises first semiconductor layers and second semiconductor layers alternately stacked over a substrate; forming a dummy gate structure over the fin structure; removing a portion of the fin structure uncovered by the dummy gate structure; performing a selective etching process to laterally recess the first semiconductor layers, including injecting a hydrogen-containing gas from a first gas source of a processing tool to the first semiconductor layers and the second semiconductor layers; and injecting an Fgas from a second gas source of the processing tool to the first semiconductor layers and the second semiconductor layers; forming inner spacers on opposite end surfaces of the laterally recessed first semiconductor layers of the fin structure; and replacing the dummy gate structure and the first semiconductor layers with a metal gate structure.