A SiOC film 7 exposed at the bottom of a contact hole 11 is changed to an altered layer 12 after the contact hole 11 is formed, so that a selection ratio of the altered layer 12 and a semiconductor substrate 1 can be increased and the altered layer 12 can be selectively removed by etching. Thus it is possible to suppress an amount of etching on a base substrate and form a contact while suppressing leakage from the substrate even when stacked layers are displaced from each other.