AES STUDY OF BORON-DIFFUSION IN SILICON FROM A BORON-NITRIDE SOURCE WITH HYDROGEN INJECTION

Boron diffusion in silicon from a boron nitride source with a doping step in hydrogen was characterized with Auger electron spectrometry and depth profiling. The thickness and the composition of the boron-rich layer (BRL) which grows in this process were studied as a function of the oxygen concentration in the gas phase in the final cooling step. Oxygen diffuses to and through the BRL to the BRL/Si interface: The silicon in the boron-rich layer is preferentially oxidized, and a silicon dioxide layer grows for a high enough oxygen concentration. A chemical etch in hydrofluoric acid can then remove this oxide layer and lift away the remaining BRL. A range in oxygen concentration was found for which the doping level is practically the same as for sample diffused with no oxygen in the cooling step, but subjected to an oxidation at low temperature, which is the usual method for the BRL removal. © 1979, The Electrochemical Society, Inc. All rights reserved.