Patent ID: 8603904

Claim:
A manufacturing method of a semiconductor device, comprising: forming a contact hole in an interlayer insulating film over a semiconductor substrate, to expose a surface of the semiconductor substrate, whereby a natural oxide film is formed on the exposed surface of the semiconductor substrate; placing the semiconductor substrate on which the natural oxide film is formed, in a mixed gas including ammonia and HF at a temperature of less than 50° C., to form a silicon ammonium fluoride on the surface of the semiconductor substrate by reacting the natural oxide film with the ammonia and the HF; placing the semiconductor substrate on which the silicon ammonium fluoride is formed in an inert gas at a temperature higher than 100° C., to remove the silicon ammonium fluoride on the surface of the semiconductor substrate, resulting in removing the natural oxide film on the surface of the semiconductor substrate; and embedding a conductor in the contact hole to form a contact plug after removing the natural oxide film on the surface of the semiconductor substrate.