STRUCTURE AND FORMATION METHOD OF SEMICONDUCTOR DEVICE WITH EPITAXIAL STRUCTURES

A semiconductor device structure and a formation method are provided. The method includes forming a protruding structure over a substrate. The protruding structure has multiple sacrificial layers and multiple semiconductor layers, and the sacrificial layers and the semiconductor layers have an alternating configuration. The method also includes forming a gate stack to wrap a portion of the protruding structure. The method further includes forming an epitaxial structure abutting edges of the semiconductor layers. The formation of the epitaxial structure includes forming a lower semiconductor portion on a bottom of the recess and forming an upper semiconductor portion over the lower semiconductor portion. The upper semiconductor portion and the lower semiconductor portion are oppositely doped.