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 compound semiconductors in pure nitrogen or hydrogen was investigated for the fabrication of metal‐insulator‐semiconductor field‐effect transistors (MISFETs). 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/cm 2 . A sequence of high‐resolution x‐ray photoelectron spectra were obtained at four depths through the silicon interfacial region for the In , 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 peak consistent with , , or 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 implanted with silicon at 150 keV to a dose of showed peak atomic concentrations of at 0.2 μ.m for RTA of 15, 30, or 60s at 700°C in pure or . The atomic concentration profiles showed no diffusion of the implanted silicon in the during RTA. A pure 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 MISFETs. The MISFETs had threshold voltages of +1V, transconductance of 27 mS/mm, peak channel mobility of 1200 cm 2 V −1 s −1 , and drain current drift of only 7%.