Quantitative Analysis on the Hydroxyl Content of Photomask Glass Fabricated by Flame Hydrolysis

Abstract

Flame Hydrolysis Deposition(FHD) method is widely employed to deposit SiO2 soot, where utilizes the hydrolysis of SiCl4 in the high temperature H2-O2 flame and produces silica glasses. In this process, the control of hydroxyl content crucial for the optical transmission, optical durability, and film adhesion for subsequent process, so on. In this study, the convenient method to determine the hydroxyl content in silica glass was tried based on the FT-IR. Two types of the silica glass samples were prepared by Vapor-phase Axial Deposition(VAD) and FHD method and the hydroxyl contents were compared to various commercial products. The hydroxyl peak at ~3500cm-1 was analyzed qualitatively and quantitatively, and optical density was interpreted to hydroxyl content. To do this, standard extinction curves and the resulting optical extinction coefficient for each type of silica glass were determined.