Photomask for off-axis illumination and method of fabricating the same

Abstract

A photomask that is capable of implementing off-axis illumination (OAI), and a method of fabricating the same, are provided. The photomask includes a transparent substrate, a plurality of opaque patterns formed on the front surface of the transparent substrate, for defining a floodlighting portion for forming patterns, and a plurality of phase gratings formed on the back surface of the transparent substrate, allowing off-axis illumination (OAI) of an incident light source beyond the OAI limit of exposure equipment, allowing use in the outmost region of an aperture, and allowing modified illumination having a shape suitable for the layout of the opaque patterns.

Dependencies are inferred from the claim text.