The measurement of surface boron on silicon wafers annealed in vacuum and gas ambients

Abstract

Thermal desorption of surface oxide from silicon wafers has been studied in ultrahigh vacuum and in hydrogen by secondary-ion mass spectrometry. Heating in 132 Pa hydrogen virtually eliminates residual boron contamination which creates a p-type surface layer on vacuum-annealed wafers. Lower pressures of hydrogen and substitution of nitrogen have proved less efficient in reducing surface boron concentration. In-situ ellipsometry indicates differences in reaction kinetics for oxide desorption in vacuum and in hydrogen.