EFFECT OF REACTIVE-ION BOMBARDMENT ON THE PROPERTIES OF SILICON-NITRIDE AND OXYNITRIDE FILMS DEPOSITED BY ION-BEAM SPUTTERING

Silicon nitride and oxynitride films of very low hydrogen content have been deposited on silicon at low temperatures (150-200-degrees-C) usi ng ion-beam sputtering. A dual-ion-beam sputtering technique, making s imultaneous use of an energetic argon-ion beam to sputter silicon nitr ide from a target and a low-energy oxygen or nitrogen ion beam to reac t with the sputtered films on the substrate, has been employed to cont rol the composition of the films. A precise control of film compositio n independent of deposition rate has been achieved through the control of oxygen/nitrogen ion-beam parameters and gas flow ratios. The films have been characterized by the measurement and study of refractive in dex, chemical etch rate, infrared absorption, and x-ray photoelectron spectra. A direct correlation between film properties with oxygen cont ent has been obtained for silicon oxynitride films. The electrical pro perties have been studied by the measurement of the characteristics of metal-insulator-semiconductor capacitors fabricated using the deposit ed films. In situ ion-beam oxidation of silicon prior to the oxynitrid e deposition has resulted in a film with a low insulator charge number density (3.5 x 10(11) Cm-2) and interface trap density (4 x 10(11) CM -2 eV-1), which is suitable for device applications.