Structure and formation method of semiconductor device with epitaxial structures

Abstract

A method for forming a semiconductor device structure includes forming a fin structure, and the fin structure has multiple sacrificial layers and multiple semiconductor layers laid out alternately. The method also includes forming a gate stack wrapped around the fin structure and forming a spacer layer extending along sidewalls of the fin structure and the gate stack. The method further includes partially removing the fin structure and the spacer layer to form a recess exposing side surfaces of the semiconductor layers and the sacrificial layers. A remaining portion of the spacer layer forms a gate spacer. In addition, the method includes forming an inner spacer layer along a sidewall and a bottom of the recess and partially removing the inner spacer layer using an isotropic etching process. Remaining portions of the inner spacer layers form multiple inner spacers. The method includes forming an epitaxial structure in the recess.