Method for fabricating an attenuated phase shift photomask by separate patterning of negative and positive resist layers with corresponding etching steps for underlying light-shielding and phase shift layers on a transparent substrate

摘要

A method for fabricating a photomask includes the steps of forming a phase shift layer, a light-shielding layer, and a negative resist layer in that order on a transparent substrate, forming a first resist pattern including a pattern corresponding to a transfer pattern by performing first exposure and development on the negative resist layer, forming a light-shielding pattern by etching the light-shielding layer using the first resist pattern as a mask, removing the first resist pattern, and then forming a positive resist layer thereon, forming a second resist pattern including a pattern corresponding to a light-absorbing pattern by performing second exposure and development on the positive resist layer, and forming a phase shift pattern by etching the phase shift layer using the second resist pattern as a mask.