Litho-only double patterning approaches: positive–negative versus positive–positive tone

Double patterning is considered the most viable option for 32- and 22-nm complementary metal-oxide semiconductor (CMOS) node development and has seen a surge of interest due to the remaining challenges of next-generation lithography systems. Most double patterning approaches previously described require intermediate processing steps (e.g., hard mask etching, resist freezing, spacer material deposition, etc.). These additional steps can add significantly to the cost of producing the double pattern. Alternative litho-only double patterning processes are investigated to achieve a composite image without the need for intermediate processing steps. A comparative study between positive–negative (TArF-P6239+N3007) and positive–positive tone (TArF-P6239+PP002) imaging is described. In brief, the positive–positive tone approach is found to be a superior solution due to a variety of considerations.