Silicon Damage Caused by Hydrogen Containing Plasmas

Abstract

This study shows that the damage observed in silicon slices after exposure to reactive ion etching in a hydrogen containing plasma is caused by physical bombardment of the surface by hydrogen ions. This conclusion is based primarily on extensive measurements of retention time, Rutherford backscattering, and Auger analysis data. When the etch gas is a mixture of and , hydrogen ions are implanted into the silicon surface to an approximate depth of 200Å. Because the etch rate of silicon in is slow, any resulting surface damage due to this plasma increases faster than can be removed by a fast silicon etch, like alone. However, the damaged layer can readily be removed by any dry or wet etching agent. Metal oxide semiconductor (MOS) measurements of charge retention indicate that an exposure to hydrogen containing plasmas for less than 5 min does not degrade the silicon surface sufficiently to be of concern for device fabrication on VLSI. Good product yields have been fabricated with a plasma that contains hydrogen.