Silicon Oxidation Studies: The Oxidation of Heavily B- and P-Doped Single Crystal Silicon

Abstract

The present oxidation study covers the 780°-1150°C temperature range using 0.001 Ω-cm Si which is heavily B- and P-doped Si (6-8 × 1019 cm-3) in dry O2 (<1 ppm H2O). Emphasis is on the lower temperatures thereby extending the scope of already published studies. For 0.001 Ω-cm Si at temperatures greater than 1000°C, the over-all oxidation rates were found to conform to the orderB doped > P doped > STD (where STD is 2 Ω-cm B-doped Si), which is in agreement with published results for the higher temperatures. However, for the lower oxidation temperatures of the present study (≥1000°C), the order for the over-all oxidation rates was found to be P doped > B doped ≤ STD The oxidation data was taken using an automated ellipsometer in situ and was analyzed using a linear-parabolic oxidation model. The resulting linear rate constants could be correlated with well-known B depletion and P accumulation effects near the Si-SiO2 interface while a consideration of the structural roles of B and P in the SiO2 network was necessary to explain the parabolic rate constants. Phase separation of B2O3 occurred in the SiO2 grown on B-doped Si and Si precipitation was observed in all the oxides grown at 1150°C but neither of these phenomena are believed to affect the oxidation kinetics. The extended temperature range showed non-Arrhenius behavior which could explain the divergent activation energies reported from published studies. © 1978, The Electrochemical Society, Inc. All rights reserved.