Synthesis and fidelity study of ultraviolet-curable hydrogen silsesquioxane analogue as an elastomeric stamp

Abstract

An analogue of hydrogen silsesquioxane (HSQ) with an epoxy-terminated inorganic polydimethylsiloxane spacer at tethered positions was prepared as a stamp for soft lithography. Nuclear magnetic resonance (NMR) spectroscopy and wide angle X-ray diffraction (WAXD) results proved the existence of a crystallite cage silsesquioxane structure embedded in an amorphous matrix. The fluid analogue was ultra-violet cured whose curing characteristic was closely related to catalyst concentration, post-bake time, and post-bake temperature. Spectroscopic analysis showed that the pattern was successfully replicated onto the HSQ analogue surface with high fidelity down to the sub-micron scale. The electron beam dosages affect the features of the replicated soft mould. The surface profile and roughness were almost identical between the hard and soft mould leading to a respectable surface roughness (R_a and R_q) of 3.0–4.5 nm and aspect ratio as high as 7.5. Synergistic effect of the rigid cage structure of silsesquioxane with a flexible organic spacer offers an efficient master mould filling.