Patent ID: 7314834

Claim:
A semiconductor device fabrication method, comprising: forming, on a substrate, a positive type photoresist film comprising an underlying resist layer formed of a diazo novolac photoresist and a surface resist layer for being inverted into a negative type by only heat treatment after light exposure; inverting the surface resist layer into a negative type by applying a mask and performing light exposure and heat treatment; exposing the entire surface of the photoresist film to light; developing the entire-surface-exposed photoresist film to thereby be processed into a resist pattern, where the surface resist layer is in an inverse tapered shape, while the underlying resist layer is in an undercut shape relative to the surface resist layer; forming, on the resist pattern, a metal film for forming electrodes and wiring; and performing a patterning by dissolving the resist pattern with a solvent and removing the metal film on the resist pattern.