Structure and formation method of semiconductor device with semiconductor nanostructures

Abstract

A semiconductor device structure and a formation method are provided. The method includes forming a fin structure over a substrate, and the fin structure has multiple sacrificial layers and multiple semiconductor layers laid out in an alternating manner. The method also includes forming a dummy gate stack extending across a portion of the fin structure and forming gate spacers over sidewalls of the dummy gate stack. The gate spacers extend across portions of the fin structure. The method further includes removing the dummy gate stack to form a trench exposing the portion of the fin structure and trimming the semiconductor layers exposed by the trench. Each of the semiconductor layers covered by the gate spacers becomes wider than each of the semiconductor layers that is trimmed. In addition, the method includes removing the sacrificial layers and forming a metal gate stack wrapped around the semiconductor layers.