Evaluation of EUV resist materials for use at the 32 nm half-pitch node

The 2007 International Technology Roadmap for Semiconductors (ITRS) ¹ specifies Extreme Ultraviolet (EUV) lithography as one leading technology option for the 32nm half-pitch node, and significant world wide effort is being focused towards this goal. Readiness of EUV photoresists is one of the risk areas. In 2007, the ITRS modified performance targets for high-volume manufacturing EUV resists to better reflect fundamental resist materials challenges. For 32nm half-pitch patterning at EUV, a photospeed range from 5-30 mJ/cm² and low-frequency linewidth roughness target of 1.7nm (3σ) have been specified. Towards this goal, the joint INVENT activity (AMD, CNSE, IBM, Micron, and Qimonda) at Albany evaluated a broad range of EUV photoresists using the EUV MET at Lawrence Berkeley National Laboratories (LBNL), and the EUV interferometer at the Paul Scherrer Institut (PSI), Switzerland. Program goals targeted resist performance for 32nm and 22nm groundrule development activities, and included interim relaxation of ITRS resist performance targets. This presentation will give an updated review of the results. Progress is evident in all areas of EUV resist patterning, particularly contact/via and ultrathin resist film performance. We also describe a simplified figure-of-merit approach useful for more quantitative assessment of the strengths and weaknesses of current materials.