Reaction of Hydrogen Fluoride Gas at High Temperatures with Silicon Oxide Film and Silicon Surface

Abstract

The chemical nature of hydrogen fluoride gas at high temperatures, 523–1173 K, for etching silicon dioxide in hydrogen ambient at atmospheric pressure is studied, for the first time. Although only a slight decrease in the silicon dioxide film thickness can be observed below 1000 K, its surface is significantly etched above 1000 K. Hydrogen fluoride gas in the temperature range of 500-1000 K in hydrogen ambient is experimentally shown to be nonreactive with silicon dioxide. The existence of water molecules is necessary for hydrogen fluoride gas to etch silicon dioxide even at high temperatures. At temperatures above 873 K, hydrogen fluoride gas can react to roughen the surface of the silicon substrate. The corrosion of silicon carbide by hydrogen fluoride gas is also observed as the formation of pits at the surface.