Imec has found a way to reduce the amount of light needed for an EUV exposure, thereby increasing scanner throughput. By increasing oxygen concentration during the post-exposure bake, the Leuven-based research hub reports a 15-20 percent faster photo-speed.
Metal-oxide resists (MORs) are prime candidates for advanced EUV, outperforming chemically amplified resists in resolution, line-edge roughness and dose-to-size behavior. They’re particularly attractive for the smallest metal layers patterned with high-NA EUV. Imec now shows that their dose response can be further tuned not by changing chemistry, but by adjusting the ambient during the critical heat step between exposure and development. The research was presented at this week’s SPIE Advanced Lithography + Patterning Conference in San Jose.
The results were achieved using Beforce, a research tool developed by Imec to investigate the role of the ambient environment on critical dimension (CD) stability and performance of MORs. “The wafer transfer and post-exposure bake are isolated from the cleanroom atmosphere and can be performed in precisely controlled environments allowed by gas injection and mixing systems. This unique ability, in combination with an integrated photo-speed measurement, was key to revealing the role of oxygen in boosting MOR’s dose response,” says Kevin Dorney, R&D team lead at Imec.
