Patent ID: 8895235

Claim:
A method for producing a photoresist pattern comprising: providing a photomask formed of a metal nanostructure for producing localized surface plasmon resonance, the metal nanostructure including a mask substrate having an irregular structure on a surface thereof and a metal film arranged on at least a protrusion of the irregular structure of the mask substrate; providing a photoresist film that is sensitive to light having a wavelength X, the photoresist being formed on a surface of a resist substrate; bringing the photomask into contact with the photoresist film; and transferring onto the photoresist film a pattern of the metal film of the photomask by generating a scattering component of light based on localized surface plasmon resonance at a surface of the metal film of the photomask by directing a light having a wavelength Y that is longer than wavelength X and 50 nm to 200 nm shorter than a peak wavelength of a plasmon resonance band of the metal nanostructure.