Extreme ultraviolet (EUV) mask absorber and method for forming the same

An extreme ultraviolet (EUV) mask comprising:

• a multi-layer (ML) reflector positioned on a substrate;
• a capping layer on a top surface of the ML reflector, wherein the capping layer includes vertical sidewalls and is formed of a reflective material;
• and
• an absorber structure positioned on a top surface of the capping layer, the absorber structure including:
• a first absorber layer having a bottom surface contacting a top surface of the capping layer, and a top surface of the first absorber layer opposite the bottom surface, wherein the first absorber layer includes non-vertical sidewalls extending from the bottom surface of the first absorber layer to the top surface of the first absorber layer, and
• wherein an outer edge of the top surface of the first absorber layer is closer to a vertical axis passing through a central point of the bottom surface of the first absorber layer than to an outer edge of the bottom surface of the first absorber layer, and
• a second absorber layer having a bottom surface contacting the top surface of the first absorber layer, and a top surface of the second absorber layer opposite the bottom surface, wherein the second absorber layer includes non-vertical sidewalls extending from the bottom surface of the second absorber layer to the top surface of the second absorber layer, and
• wherein an outer edge of the top surface of the second absorber layer is closer to the vertical axis than to an outer edge of the bottom surface of the second absorber layer.