CHEMICAL NATURE OF SILICON NITRIDE-INDIUM PHOSPHIDE INTERFACE AND RAPID THERMAL ANNEALING FOR INP MISFETS

Rapid thermal annealing (RTA) of the ion implanted indium phosphide (InP) compound semiconductors in pure nitrogen or hydrogen was investigated for the fabrication of metal-insulator-semiconductor field-effect transistors (MISFETs). InP was encapsulated during RTA by 500Å silicon nitride films made using PECVD at 300°C and 500 mtorr with a 13.56 MHz RF power density of 50 mW/cm2. A sequence of high-resolution x-ray photoelectron spectra were obtained at four depths through the silicon nitride-InP interfacial region for the In 3d5/2, P 2p, N 1s, Si 2p, and O 1s peaks to determine the chemical nature of the interface after encapsulated RTA. There was a component of the In 3d5/2 peak consistent with In(OH)3, InO-(OH), or InO2 which increased after RTA. No phosphate was observed in the P 2p peak. A significant decrease of the N-H or N-N component of the N 1s peak occurred after RTA. Secondary ion mass spectrometry atomic concentration profiles of InP implanted with silicon at 150 keV to a dose of 4 x 1013 cm−2 showed peak atomic concentrations of 2 x 1018 cm−3 at 0.2 µm for RTA of 15, 30, or 60s at 700°C in pure N2 or H2. The atomic concentration profiles showed no diffusion of the implanted silicon in the InP during RTA. A pure H2 RTA at 700°C for 30s followed by a furnace anneal at 400°C for 2h in forming gas of the phosphorus oxide/silicon dioxide gate insulator was determined to be the optimum thermal process for the fabrication of InP MISFETs. The MISFETs had threshold voltages of +1V, transconductance of 27 mS/mm, peak channel mobility of 1200 cm2 V−1 s−1, and drain current drift of only 7%. © 1990, The Electrochemical Society, Inc. All rights reserved.