Patent ID: 7491474

Claim:
A method for fabricating a mask for a lithographic imaging of structures on the mask onto a semiconductor wafer, the mask having a transparent mask substrate with a surface, and the structures being formed by transparent and opaque, or semitransparent, phase-shifting sections in a first region of the mask and being formed by phase-shifting trenches in the mask substrate in a second region of the mask, the method comprising: providing a mask blank with the mask substrate; providing a light-absorbing absorber layer on or above the surface; providing a photosensitive first resist layer on the absorber layer; performing a lithography step to define a size and position of the second region with respect to the first region and to transfer the structures to be formed in the first and in the second region into the first resist layer; transferring the structures formed in the first resist layer into the absorber layer; after transferring the structures into the absorber layer, forming the transparent and opaque sections with the patterned absorber layer in the first region; after forming the transparent and opaque sections, defining the structures in the second region; after defining the structures in the second region, removing the first resist layer; applying a photosensitive second resist layer; patterning the second resist layer, the second resist layer being almost completely opened in the second region; etching the trenches into the uncovered mask substrate only with the patterned absorber layer in the second region as a hard mask; removing the hard mask; and removing the second resist layer.