Method of making a lithography mask

A method of forming a lithography mask comprising:

• providing a low thermal expansion material (LTEM) substrate;
• forming an opaque layer on the LTEM substrate;
• forming a hard mask (HM) on the opaque layer;
• patterning the HM;
• patterning the opaque layer through the patterned HM to form a patterned mask;
• removing the patterned HM;
• and
• applying a vacuum ultraviolet irradiation (VUVI) stress-relief treatment to the patterned mask, wherein the VUVI has a wavelength range from about 13.5 nm to about 350 nm.

A method of making a lithography mask comprising:

• forming a conductive chromium nitride (CrN) layer at a first surface of a substrate;
• providing a reflective multilayer (ML) at a second, opposite surface of the substrate;
• forming an opaque layer on the ML;
• patterning the opaque layer to form a patterned mask;
• and
• applying a stress-relief treatment to the patterned mask by exposing the patterned mask to radiation, wherein the radiation has a wavelength range from about 13.5 nm to about 1064 nm, wherein the stress-relief treatment is applied to one of the first surface and the second surfaces of the patterned mask.