Novel approaches to controlling photo-resist CD in double patterning processes

Numerical aperture (NA) has been significantly improved to 1.35 by the introduction of water-based immersion 193-nm exposure tools, but the realistic minimum feature size is still limited to 40 nm even with the help of robust resolution enhancement techniques (RETs). Double patterning processes are techniques that can be used for fabricating etching mask patterns for 32-nm nodes and possibly for 22-nm nodes as well, but the aspect ratio of such etching mask patterns have been reduced with scaling. At the same time, dramatic improvements in the etching durability of photo resist have not been made. This paper introduces a robust pattern-slimming process that maintains pattern height.