Simultaneous SIMS/AES Measurements for the Characterization of Multilayer Systems

The interface region of silicon dioxide layers deposited on indium phosphide was investigated by simultaneous secondary ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES) depth profile measurements. The results of such measurements depend strongly on the ion species used for sputtering. With Ar⁺ primary ions an enhancement of the P- and In-SIMS signals occurs in the mixing zone at the interface. This effect can be explained by an increase of the ionization yield of In and P in the presence of oxygen from the SiO₂. The use of O₂ ⁺ as sputter ions enlarges the phosphorus peak at the interface while the enhancement of the In-signal diminishes. The simultaneously measured AES spectra give clear evidence of oxygen bonded In and P at the interface. Additionally, preferential sputtering of phosphorus occurs. The understanding of these effects which complicate the interpretation of SIMS and AES depth profile measurements of the system SiO₂/InP allows us to investigate the silicon dioxide layers and the interface region in order to optimize the SiO₂ deposition process, e.g. for surface passivation or MIS structures.