Semiconductor device and method for forming the same

Abstract

A method for forming a semiconductor device includes forming a lower source / drain region adjacent first channel regions; forming an insulating layer over the lower source / drain region; forming a dummy source / drain region over the insulating layer, wherein the dummy source / drain region is adjacent second channel regions, wherein the second channel regions are over the first channel regions; after forming the dummy source / drain region, forming a gate structure over the first channel regions and the second channel regions; after forming the gate structure, removing the dummy source / drain region; forming an upper source / drain region adjacent the second channel regions; forming a silicide on the upper source / drain region; and forming a contact plug on the silicide, wherein an electrical conductivity of the silicide is between an electrical conductivity of the upper source / drain region and an electrical conductivity of the contact plug.