Evolution of Silicon and Hydrogen Bonding in Silicon-Rich Nitride Films Prepared by Plasma-Enhanced Chemical Vapor Deposition and Annealed Under High Pressure

Hydrogenated silicon-rich nitride (SiN _x :H) film with stoichiometry parameter x close to 1.3 was deposited on Si substrate with the use of plasma-enhanced chemical vapor deposition at temperature 100 °C. Furnace annealing during 5 hours in Ar ambient at 1130 °C under atmospheric and high hydrostatic pressure (11 kbar, 1.1 GPa) was applied to modify the structure of the film. Its properties were studied using infrared absorption spectroscopy, Raman spectroscopy and photoluminescence. According to Raman spectroscopy data, the as-deposited film does not contain Si–Si bonds in amount which can be observed. Furnace annealing leads to segregation of excessive Si, so, local vibrations of Si–Si bonds were observed in Raman spectra. In the case of high pressure annealing, the amount of Si–Si bonds is higher compared with atmospheric pressure annealing. Surprisingly, after annealing with such high thermal budget, according to infrared spectroscopy data, the films contain hydrogen in the form of Si–H bonds. Peak due to absorbance by Si–H bond vibrations becomes even higher for the film annealed at atmospheric pressure. Dramatic changes in photoluminescence spectra and temperature dependence of photoluminescence were observed for the films annealed under high and atmospheric pressure.