Method for extreme ultraviolet lithography mask treatment

A reflective mask, comprising:

• a substrate comprising a front side and a back side;
• a conductive film on the back side of the substrate;
• a reflective multilayer over the front side of the substrate;
• a capping layer over the reflective multilayer;
• an absorber layer over the capping layer and comprising a top surface, wherein the absorber layer comprises tantalum boride;
• and
• a protection layer in direct contact with the top surface of the absorber layer,
• wherein a nitrogen concentration of the protection layer is greater than a nitrogen concentration of the absorber layer.

A reflective mask, comprising:

• a reflective multilayer disposed over a front side of a substrate;
• a capping layer disposed over the reflective multilayer;
• an absorber layer disposed over the capping layer and comprising a top surface and a sidewall surface;
• and
• a protection layer comprises a first portion extending along the top surface of the absorber layer and a second portion extending along the sidewall surface of the absorber layer, and the second portion is spaced apart from the reflective multilayer by the capping layer,
• wherein the absorber layer is formed of a first material and the protection layer is formed of a second material that is less easily to be oxidized than the first material.