Out-of-band insensitive polymer-bound PAG for EUV resist

Abstract

Out of band (OoB) radiation has been regarded as one of the key issues on Extreme Ultra Violet Lithography (EUVL). OoB light especially in the deep ultraviolet (DUV) region have a negative impact on image contrast and resist profile, since general photo acid generator (PAG) used in chemically amplified EUV resist are also sensitive for DUV. It is reported that a Spectral Purify Filter (SPF) would eliminate OoB radiation. However it expense a large reduction in EUV power and hence throughput, so it is reported that HVM EUV exposure tool would not employ SPF. Therefore, both EUV sensitive and DUV insensitive are required property to overcome OoB radiation issue by resist material itself. Consideration of PAG cation structure was proceeded to control absorption for DUV. Based on the concept, OoB insensitivity was investigated both on blend resist platform and Polymer Bound PAG (PBP) platform. OoB insensitive concept was confirmed with UV spectrum and sensitivity for KrF and ArF. The OoB insensitive PAG cation worked well on PBP, while dark loss are seen on blend resist platform due to lack of inhibition effect. Lithographic performance would be exhibited using Alpha Demo Tool (ADT) and NXE3100. Outgassing property on witness sample (WS) and Residual Gas Analysis (RGA ) will be also discussed.