The densities of fixed charge false(QOXfalse) and trapping centers false(NSSfalse) on thermally oxidized silicon surfaces have been measured by the MOS capacitance technique upon annealing in O2, N2, He, and vacuum at various temperatures from 600° to 1100°C. These surface characteristics are always determined by the conditions of the final high‐temperature process, except for QOX , which will never increase in neutral ambients. In all atmospheres, higher annealing temperatures yield lower QOX values. It was also found that the NSS values are very sensitive toward trace amounts of water in the high‐temperature ambient. They decrease for increasing water vapor pressure. Effects of other impurities were not observed in this study. Based on saturation values and kinetic data a discussion is given of some models for both types of centers.

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 CF4 and H2, hydrogen ions are implanted into the silicon surface to an approximate depth of 200~. Because the etch rate of silicon in CF4/H2 is slow, any resulting surface damage due to this plasma increases faster than can be removed by a fast silicon etch, like CF4 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.