Photomask used for fabricating semiconductor device, includes transparent substrate, opaque patterns and phase gratings

摘要

A photomask (50) comprises a transparent substrate; opaque patterns formed on a front surface of the substrate; and phase gratings (150) formed on a back surface of the substrate, allowing off-axis illumination (OAI) of an incident light source beyond an OAI limit of an exposure equipment. A photomask comprises a transparent substrate; opaque patterns formed on a front surface of the substrate, for defining a floodlighting portion for forming patterns; and phase gratings formed on a back surface of the substrate, allowing OAI of an incident light source beyond an OAI limit of exposure equipment, allowing use in an outmost region of an aperture and allowing modified illumination having a shape suitable for a layout of the opaque patterns. An independent claim is also included for a method of fabricating a photomask comprising forming opaque patterns for defining a floodlighting portion for forming patterns, on a front surface of a substrate; and forming phase gratings on a back surface of the substrate.