According to one aspect of the invention, there is provided a semiconductor device fabrication method having: forming a film on a semiconductor substrate; forming a mask comprising a predetermined pattern on the film; etching one of the film and the semiconductor substrate by using the mask; and performing at least one of the steps of performing a treatment using one of an aqueous solution of at least one of ammonia and amine, the amine being selected from primary amine, secondary amine, tertiary amine, and quaternary amine, a treatment using a liquid chemical containing fluorine and at least one of amine, the amine being selected from primary amine, secondary amine, tertiary amine, and quaternary amine and fluorine, and a treatment using a liquid chemical containing at least ammonia and fluorine and including a pH of not less than 6, particularly, not less than 9.