Liquid phase silylation of Shipley SPR500A-series resists using top surface imaging

Top Surface Imaging (TSI) is a well established technique to improve resolution of optical lithography, deep UV (248 nm) lithography and 193 nm lithography. The Positive Resist Image by Dry Etching (PRIME) process is a high-resolution single layer lithography scheme incorporating electron-beam exposure, near UV exposure (365 nm), silylation and dry development. In this paper, the liquid-phase silylation process step in PRIME with Shipley SPR500A-series resists is experimentally, investigated, and a new efficient process has been developed The impact of different silylating agents is characterised using FT-IR spectroscopy SIM spectrometry and cross-sectional SEM and TEM. Liquid-phase silylated patterns of SPR505 and SPR510 resist are presented, indicating almost vertical silylation sidewall profiles and high-silylation contrast when using Hexamethylcyclotrisiloxane (HMCTS) silylating agents. Results show that in case of e-beam exposure, a dose of 50 C/cm² at 30 keV is efficient to crosslink the resist and prevent silylation.