With the slipping of the insertion node for extreme ultraviolet lithography, demands on resist resolution have increased further stressing sensitivity requirements. A variety of resists, both chemically amplified and not, have been developed meeting resolution needs, but falling short on sensitivity and line-width roughness (LWR). Note that resolution is an absolute mandatory requirement, the true tradeoff that must be considered is between sensitivity and contact hole printing is a crucial application for extreme ultraviolet lithography and is particularly challenged by resist sensitivity due to inherent inefficiencies in darkfield contact printing. Checkerboard strong phase shift masks have the potential to alleviate this problem through a 4× increase in optical efficiency. The feasibility of this method is demonstrated using the SEMATECH-Berkeley Microfield Exposure Tool pseudo phase shift mask configuration and preliminary results are provided on the fabrication of an etched multilayer checkerboard phase shift mask.
2015 The Society of Photopolymer Science and Technology (SPST)