Semiconductor device with low resistivity contact structure and method for forming the same

A method for forming a semiconductor device structure, comprising:

• providing a semiconductor substrate having a fin with an epitaxial source/drain region, wherein the epitaxial source/drain region comprises silicon, germanium or a combination thereof;
• forming an insulating layer over the fin;
• forming a contact opening in the insulating layer to expose the epitaxial source/drain region;
• performing a deposition process to form a metal layer over a sidewall and the bottom of the opening, so that a metal silicide or germanide layer is formed on the exposed epitaxial source/drain region by the deposition process;
• performing a first in-situ etching process using a metal halide as a process gas, so as to etch at least a portion of the metal layer;
• performing an in-situ nitridation treatment on the sidewall and the bottom of the opening, so as to form a nitrogen-containing metal silicide or germanide layer over the bottom of the opening;
• and
• forming a fill metal material layer over the nitrogen-containing metal silicide or germanide layer and in the opening.

A semiconductor device structure, comprising:

• a semiconductor substrate having a conductive region made of silicon, germanium or a combination thereof;
• an insulating layer over the semiconductor substrate;
• a fill metal material layer in the insulating layer;
• and
• a nitrogen-containing metal silicide or germanide layer between the conductive region and the fill metal material layer.