Plasma Deposited Silicon Nitride for Gallium Arsenide Encapsulation

Abstract

The composition and annealing characteristics of plasma deposited silicon nitride encapsulating films on ion implanted gallium arsenide have been investigated. X‐ray photoelectron spectroscopy was employed to study the surface of the semi‐insulating substrates after cleaning in organic solvents, and , , and solutions prior to encapsulation. The composition of silicon nitride films deposited with 30 kHz RF excitation was determined through Auger electron spectroscopy and infrared spectroscopy as a function of the deposition conditions. Most of the films had a silicon to nitrogen ratio between 0.71 and 0.76 and a hydrogen concentration between 10 and 19%. substrates implanted with silicon at 100 keV to a dose of and annealed at 800°C had peak electron concentrations of at a depth of 0.1 μm. High frequency encapsulated substrates implanted at 100 keV to a dose of and 150 keV to a dose of had peak electron concentrations of and at depths of 0.1 and 0.12 μm respectively. A Schottky‐gate field effect transistor with a 3 μm gate length which was fabricated using the silicon nitride encapsulant had a transconductance of 30 mS/mm.