Diffusion of Ion-Implanted Arsenic in Thermally Grown SiO₂Films

Abstract

The diffusion of As implanted in thermally grown SiO2was studied at temperatures in the range 1000°-1200°C using N2and O2as ambients. Concentrations were between 3 x 1015and 3.5 x 1016As+ions cm-2. Energies of 60 and 340 keV were used. Because of As loss due to evaporation, significant quantitative data could only be obtained for deep implants. N2-annealed samples exhibit low diffusion rates at high concentrations (above the middle of the 1019cm-3range). Larger diffusion rates are observed at lower concentrations. In the samples treated in 02, the opposite concentration dependence of the diffusivity is observed. The shape of the profiles suggests that in both cases a high and a low concentration phase exists. A model is presented assuming that in 02a fully oxidized structure and in N2an oxygen deficient network is obtained as a first step in the annealing process. There are indications that the ambient also affects the diffusion rate during further high temperature treatment of these structures, probably through the concentration of oxygen vacancies. © 1984, The Electrochemical Society, Inc. All rights reserved.