Abstract: A method of fabricating a semiconductor device wherein, when etching a single-crystal silicon film or polysilicon film according to a dry etching process in which SF.sub.6 is used as a main etching gas, a deposition film is formed beforehand on the surface of the material to be etched by performing etching using a fluorine family etching gas which contains C and H. In the initial stage of etching, by using this deposition film as a mask to prevent etching in the vertical direction (direction of depth), etching of the material advances in the horizontal direction and thus the material having tapered etched shape is obtained. In doing so, there are accomplished good filling properties and good coverage and levelness.