Advanced self-aligned DP process development for 22-nm node and beyond

Although numerical aperture (NA) has been significantly improved to 1.35 by the introduction of water-bases immersion 193-nm exposure tools, 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. Although several double patterning processes have been introduced such as LELE[1], LLE[2] and the self-aligned spacer process, LELE and LLE suffer from the need for high overlay accuracy. The self-aligned spacer process[3], meanwhile, has drawn much attention as an effective means of forming repetitive patterns easily. This paper presents results of innovative experiments on the fabrication of 22-nm node patterns by the DP spacer process.