Correlation of EUV resist performance metrics in micro-exposure and full-field EUV projection tools

We describe progress in implementation of blur-based resolution metrics for EUV photoresists. Three sets of blur metrics were evaluated as exposure-tool independent comparison methods using the Sematech-LBNL EUV microexposure tool (MET) and ASML α-Demo Tool (ADT) full-field EUV scanner. For the two EUV resists studied here, deprotection blurs of 15 nm are consistently measured using blur estimation methods based on corner rounding, contact hole exposure latitude, and process window fitting using chemical amplification lumped parameter models. Agreement between methods and exposure tools appears excellent. For both resists, SRAM-type lithographic diagnostic patterns at 80 nm pitch are only modestly sensitive to OPC blur compensation and display robust printability (RELS ~ ILS near 50 μm-1 for multiple trench geometries) on the ASML ADT. These findings confirm the continuing utility of blur-based metrics in a) guiding resist selection for use in EUV process development and integration at the 22 nm logic node and below, and b) providing an exposure-tool independent set of metrics for assessing progress in EUV resist development.

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