THE PREPARATION, CHARACTERIZATION AND APPLICATION OF PLASMA-ENHANCED CHEMICALLY VAPOR-DEPOSITED SILICON NITRIDE-FILMS DEPOSITED AT LOW-TEMPERATURES

Silicon nitride films are successfully deposited using plasma-enhanced chemical vapour deposition (PECVD) at the low substrate temperature range between room temperature and 300-degrees-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-degrees-C), reactant gas ratio (NH3:SiH4 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.