The preparation, characterization and application of plasma-enhanced chemically vapour deposited silicon nitride films deposited at low temperatures

Abstract

Silicon nitride films are successfully deposited using plasma-enhanced chemical vapour deposition (PECVD) at the low substrate temperature range between room temperature and 300°C. The composition, deposition rate, etch rate, film uniformity and refractive index of the low temperature silicon nitride films are measured as functions of deposition substrate temperature (room temperature to 300°C), reactant gas ratio ( NH 3: SiH 4 ratio from 0.5 to 20), and r.f. power (30–230 W). The silicon nitride films deposited at room temperature are found to have low total stress. The low temperature PECVD silicon nitride films have been used successfully in a lift-off process for the fabrication of self-aligned gate GaAs metal-semiconductor field effect transistors MESFET and InP metal-insulator-semiconductor field effect transistors MISFET.