Extreme ultraviolet mask and method of manufacturing the same

A method of forming a mask, the method comprising:

• providing a mask blank, the mask blank including a reflective multilayer over a substrate, a capping layer disposed on the reflective multilayer, an absorber layer directly over the capping layer, and a hard mask layer directly over the absorber layer;
• forming a middle layer over the hard mask layer, wherein the middle layer comprises a plurality of sublayers, the plurality of sublayers comprising a first sublayer comprising a silicon-containing material, and a second sublayer comprising Pd or Ni, wherein the first and second sublayers are an alternating pair;
• forming a photo resist layer over the middle layer;
• patterning the photo resist layer to generate a patterned photo resist layer;
• etching the middle layer through the patterned photo resist layer to generate a patterned middle layer;
• removing remaining photo resist layer after etching the middle layer;
• after removing the remaining photo resist layer and etching the middle layer, applying a dry-etching process to the hard mask layer through the patterned middle layer to pattern the hard mask layer to generate a patterned hard mask layer;
• after the hard mask layer is patterned, removing the middle layer;
• and
• patterning the absorber layer using the patterned hard mask layer as an etching mask,
• wherein the dry-etching process has a first removal rate of the hard mask layer and a second removal rate of the middle layer, and a ratio of the first removal rate of the hard mask layer to the second removal rate of the middle layer is greater than 5, and
• wherein a thickness ratio of the photo resist layer to the middle layer is 1:1 and a thickness ratio of the middle layer to the hard mask layer is 1:1.

A method of forming a mask, the method comprising:

• forming a middle layer on a mask film stack comprising a substrate, a reflective multilayer on the substrate, a capping layer on the reflective multilayer, an absorber layer directly on the capping layer and a hard mask layer directly on the absorber layer;
• forming a photo resist layer over the middle layer, wherein the middle layer comprises polysiloxanes;
• patterning the photo resist layer;
• patterning the middle layer by using the patterned photo resist layer to generate a patterned middle layer;
• removing remaining photo resist layer after patterning the middle layer;
• patterning the hard mask layer by using the patterned middle layer to generate a patterned hard mask layer after removing the remaining photo resist layer;
• and
• patterning the absorber layer by using the patterned hard mask layer as an etching mask,
• wherein the middle layer comprises a plurality of sublayers, wherein at least one of the sublayers comprises Pd or Ni and at least another of the sublayers comprises polysiloxanes,
• wherein patterning the hard mask layer includes etching the hard mask layer via a dry-etching process using to the patterned middle layer as a mask, wherein the dry-etching process has a first removal rate of the hard mask layer and a second removal rate of the middle layer, and a ratio of the first removal rate of the hard mask layer to the second removal rate of the middle layer is greater than 5, and
• wherein a thickness ratio of the photo resist layer to the middle layer is 1:1 and a thickness ratio of the middle layer to the hard mask layer is 1:1.