Optimized SiO2/InP structures prepared by electron cyclotron resonance plasma

A fabrication procedure for high quality SiO2/InP structures has been developed using electron cyclotron resonance plasmas. The oxidation of InP in an oxygen plasma was investigated by x-ray photoelectron spectroscopy (XPS) to prepare an appropriate interfacial layer made of a single phase native InP oxide. Silicon dioxide films were prepared on InP (100), using SiH4 and oxygen plasma. We studied the effect of plasma parameters (substrate temperature, flow rates, flow rate ratio, chamber pressure, and annealing conditions) on the structural and electrical properties of the films. The SiO2 films and the SiO2/InP interface were characterized in situ by XPS and ex situ by spectroellipsometry. Electrical C-V and I-V measurements were performed on metal-insulator-semiconductor structures. The films are stoichiometric for deposition temperatures ranging from 150 to 300 degrees C, with bulk properties very close to those of thermally grown silicon dioxide. Optimized SiO2/InP structures, with an interface state density of 10(11) cm(-2) eV(-1) and a long term drift that is lower than 0.2 eV after 10(3) s of stress under 4 V in accumulation, are obtained for a deposition temperature of 200 degrees C and with a 10 Angstrom thick single phase native oxide prepared in indirect plasma conditions. It was found that the electrical interfacial properties of the SiO2/InP structures are directly correlated to their interfacial chemistry. (C) 1996 American institute of Physics.