Influences of Preparation Conditions of Sols on Hardening Behaviors of Silica Gel Films for Micro-Patterning.

Abstract

Changes in refractive index, thickness and structure of the poly (ethylene glycol), (PEG), -containing silica gel films, prepared under various concentrations of hydrochloric acid during the exposure to an ambient atmosphere at room temperature, have been investigated to determine the influence of preparation conditions on the hardening behavior of the films in a patterning process. The PEG-containing silica gel films, derived from silica sols which were prepared under lower hydrochloric acid concentration, showed a steep increase in refractive index and large shrinkage upon increasing the exposure time. The increase in refractive index and shrinkage of the films were found to reflect the decrease of Si-OH groups and the development of Si-O-Si network in the films, accoding to infrared absorption spectra. The process time to emboss micro-patterns was shortened by using the gel films derived from silica sols which were prepared under a low hydrochloric acid concentration. This result suggests that the silica gel film with a low degree of polymerization hardens rapidly.