Thin SiON film grown at low temperature (400 °C) by microwave-excited high-density Kr/O₂/N₂ plasma

It is demonstrated that thin oxynitride (SiON) films can be grown on single crystal (100) silicon substrates at a growth temperature of 400 °C, yielding high-quality electrical insulating and reliability properties which are compatible with the IC industry requirements. This is a drastic reduction in the growth temperature with respect to thermally grown SiO₂ films at 1000 °C, which are conventionally used in semiconductor device fabrications. The realization of this growth method is made through the employment of high-density Kr/O₂/N₂ microwave-excited (2.45 GHz) plasma techniques. It is found that the electrical properties of the oxynitride films are strongly affected by the amount of the N₂ added to the process gas mixture. For a properly selected mixture, the characteristics of the plasma-grown oxynitride films are shown to exhibit clear advantages with respect to those of SiO₂ gate insulator films, grown by a conventional dry oxidation at 1000 °C, presently used in the IC industry. They demonstrate higher charge-to-breakdown (Q_BD) values, lower stress-induced leakage currents, and significantly lower gate voltage shifts (δV_G). Accordingly, it is suggested that oxynitride films grown by the Kr/O₂/N₂ plasma technique are promising candidates for gate insulator films in scaled down MOS devices for the realization of future ultralarge-scale integration.