Structure and formation method of semiconductor device with backside conductive contact

Abstract

A method for forming a semiconductor device structure includes forming a fin structure over a substrate. The fin structure has a base layer, and the fin structure has multiple sacrificial layers and multiple semiconductor layers laid out in an alternating manner over the base layer. The method also includes partially removing the fin structure to form an opening exposing side surfaces of the semiconductor layers, the sacrificial layers, and the base layer. The method further includes partially or completely removing the base layer to form a recess, forming a protective structure in the recess, and forming an epitaxial structure filling the opening. In addition, the method includes partially removing the substrate from a backside surface of the substrate to form a contact opening exposing the protective structure and extending towards the epitaxial structure. The method includes forming a backside conductive contact in the contact opening.