Progress in EUV resists towards high-NA EUV lithography

摘要

High-NA extreme ultraviolet lithography (EUVL) is going to deliver the high-volume manufacturing (HVM) patterningfor sub-7 nm nodes for the semiconductor industry. One of the critical challenges is to develop suitable EUV resists at highresolution with high sensitivity and low line-edge roughness (LER). The resist performance is generally limited by theresolution-LER-sensitivity (RLS) tradeoff and it is critical to find new resists that have a performance beyond this tradeoff.EUV interference lithography (EUV-IL) is a powerful and efficient technique that can print high resolution: half pitch(HP) down to 6 nm nanostructures. In this work, we evaluate the performance of the EUV resists, including molecularresist, inorganic resist, chemically-amplified (CAR) and metal sensitizer chemically-amplified resist (Metal-CAR). Sixresists with the best performance have been compared in dose-to-size, line-edge roughness, exposure latitude for half pitch16 nm and 14 nm. The molecular resist A showed lowest dose to resolve HP 16 nm (35 mJ/cm~2) and 14 nm (41 mJ/cm~2)but with high line edge roughness (LER 3.5 nm). CAR resist C provided lowest LER 1.9 and 1.8 nm for HP 16 nm andHP 14 nm, respectively, but with higher doses 74 mJ/cm~2 (HP 16 nm) and 69 mJ/cm~2 (HP 14 nm). The inorganic resistshowed comprehensive good performance, giving low LER of 2.1 nm with 50 mJ/cm2 and 42 mJ/cm~2 for HP 16 nm andHP 14 nm, respectively. Using the simplified Z-factor model, we showed that the LER of the resists was improved overthe last two years. As the inorganic resist could resolve HP 11 nm with dose 67 mJ/cm2, we conclude it to be the currentbest candidate to partially resolve the RLS tradeoff problem and could be the potential EUV resist for semiconductortechnological node printing.