Semiconductor device and manufacturing method thereof

Abstract

A method includes forming a fin structure including a plurality of first semiconductor layers and a plurality of second semiconductor layers alternately stacked over a substrate. A dummy gate structure is formed across the fin structure. The exposed second portions of the fin structure are removed. A selective etching process is performed, using a gas mixture including a hydrogen-containing gas and a fluorine-containing gas, to laterally recess the first semiconductor layers. Inner spacers are formed on opposite end surfaces of the laterally recessed first semiconductor layers. Source/drain epitaxial structures are formed on opposite end surfaces of the second semiconductor layers. The dummy gate structure is removed to expose the first portion of the fin structure. The laterally recessed first semiconductor layers are removed. A gate structure is formed to surround each of the second semiconductor layers.