Reaction of hydrogen fluoride gas at high temperatures with silicon oxide film and silicon surface

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 sil icon dioxide film thickness can be observed below 1000 K, its surface is si gnificantly etched above 1000 K. Hydrogen fluoride gas in the temperature r ange of 500-1000 K in hydrogen ambient is experimentally shown to be nonrea ctive with silicon dioxide. The existence of water molecules is necessary f or hydrogen fluoride gas to etch silicon dioxide even at high temperatures. At temperatures above 873 K, hydrogen fluoride gas can react to roughen th e surface of the silicon substrate. The corrosion of silicon carbide by hyd rogen fluoride gas is also observed as the formation of pits at the surface .