Silicon nitride and silicon dioxide films for MISFETs on indium phosphide

Phosphorus rich silicon nitride and silicon dioxide dielectric films were investigated as gate insulators for metal-insulator-semiconductor field-effect transistors (MISFETs) on indium phosphide compound semiconductors. The paper discusses the insulator depositions, film characterizations, MISFET fabrication and MISFET electrical results. The depositions were carried out in a direct plasma deposition chamber. The system is a capactively coupled Technics PEII-A system modified for depositions. The system uses a 13.56 mHz Rf generator as the plasma source. The insulators are deposited on Zn doped p-type InP with a thickness between 500A and 1000A. The silicon nitride is deposited using nitrogen, ammonia and silane. Flow rates, power, pressure and temperature were varied to obtain maximum dielectric characteristics. The deposition was done at 30 watts, 500 mTorr and 3000C. Film resistivity was of the order of 10/sup 14/ ohm cm. Silicon dioxide was deposited using nitrous oxide and silane at 30 watt, 2750C and 800 mTorr. The films have a resistivity of the order of magnitude at 10/sup 14/ ohm cm. The phosphorus rich interface was deposited using a red amorphous phosphorus in a crucible. The phosphorus was placed near the test sample and a nitrogen plamsa was done. Then a short nitrous oxide plamsa is done to form a phosphorous rich region. The nitrogen plasma was required to obtain this region as seen by Auger electron spectroscopy