Patent ID: 7306681

Claim:
A method for cleaning a semiconductor substrate, comprising the steps of: (a)providing a semiconductor substrate comprising a gate electrode surrounded by a spacer, and a plurality of shallow trench isolations and a plurality of exposed regions of said semiconductor substrate between said gate electrode and said shallow trench isolations before performing a selective epitaxial growth; (b)cleaning a surface of said semiconductor substrate with a first acid solution consisting of hydrofluoric acid and deionized water, wherein said first acid solution is diluted with deionized water with a ratio of DI H 2 O:HF=100:1 to 300:1; and (c)cleaning the surface of said semiconductor substrate with a second acid solution consisting of hydrogen chloride acid and hydrogen peroxide (H 2 O 2 ) and deionized water, wherein said semiconductor substrate is not cleaned with a mixture of ammonium hydroxide (NH 4 OH), hydrogen peroxide (H 2 O 2 ) and deionized water, before the step (c) and after the step (b), whereby said selective epitaxial growth is performed on said semiconductor substrate after said steps (a), (b), and (c).