Growth and electronic properties of thin Si3N4 films grown on Si in a nitrogen glow discharge

Thin Si3N4 films were grown on Si by direct exposure to a low-temperature (250–650 °C) nitrogen glow discharge at 13.56 MHz. The activation energy for growth is 0.3±0.12 eV. Their chemical and electronic, bulk, and interfacial properties are studied as a function of the film thickness and growth temperature. The ultrathin films (d<100 Å) exhibit an average breakdown field of 10–12 MV/cm, a dielectric constant equal to 5.5, and are effective barriers against oxidation at 1000 °C. Conduction in ultrathin films is via Fowler–Nordheim tunneling over the temperature range 77–420 K. Deep-level transient spectroscopy analysis reveals the presence of two majority-carrier (hole) traps at the interface, with activation energies 0.1 and 0.35 eV, respectively. The trap at EV+0.35 eV is attributed to the Si dangling bond defect while the trap at EV+0.1 eV could be attributed to a structural defect that is in situ annealed at growth temperatures higher than 500 °C. The interface state concentration is a sensitive function of the growth temperature and varies in the range 8×1010–6×1012 cm−2.