Properties of the ultra-thin silicon-oxynitride films deposited by using plasma-assisted N₂O oxidation for semiconductor device applications

In this paper, we report our investigation on the effect of the presence of a high concentration of nitrogen in a silicon-oxide layer deposited by using plasma-assisted nitrous-oxide oxidation. The results of the ellipsometric measurement, the capacitance-voltage characterization studies, and the processing conditions are presented. P-type silicon wafers with 10-20 ohm-cm resistivities, 4-inch diameter; and (100) orientations were used for the fabrication of metal-insulator-semiconductor (MIS) capacitors. The silicon-oxynitride films deposited using by an inductively-coupled-plasma chemical-vapor deposition (ICPCVD) method under three different process conditions. In the first case, the RF power and the substrate temperature were kept constant while the deposition time was varied from 1 to 30 minutes. In the second case, the substrate temperature and the deposition time were kept constant while the RF power was varied from 50 to 450 W. In the thirds experiment, the RF power and deposition time were fixed while the substrate temperature was varied from 150 to 550°C In all above processes, the nitrous-oxide flow and the working pressure were kept constant. The results of the present study indicate the suitability of the deposited films for applications in ultra very thin film transistors (UVTFT) and NVM (nonvolatile memory) devices.