Patent ID: 7524620

Claim:
A pattern formation method using a photomask having a mask pattern formed on a transparent substrate and a transparent portion of said transparent substrate where said mask pattern is not formed, the pattern formation method comprising the steps of: (a) forming a resist film on a substrate; (b) irradiating said resist film with said exposing light through said photomask; and (c) forming a resist pattern by developing said resist film having been irradiated with said exposing light, wherein in said photomask, said mask pattern includes a main pattern to be transferred through exposure and an auxiliary pattern that diffracts exposing light and is not transferred through the exposure, said main pattern is composed of a first semi-shielding portion that has first transmittance for partially transmitting said exposing light and transmits said exposing light in an identical phase with respect to said transparent portion, and a phase shifter that transmits said exposing light in an opposite phase with respect to said transparent portion, said auxiliary pattern is made from a second semi-shielding portion that has second transmittance for partially transmitting said exposing light and transmits said exposing light in the identical phase with respect to said transparent portion, and a pattern width of said auxiliary pattern is smaller than that of said main pattern.