High Quality of Ultra-Thin SiO x N y Films Prepared in Nitrous Oxide Ambients Using Thermal Low-Pressure Oxynitridation.

The thermal low-pressure oxynitridation of Si(100) in N2O has been studied for ultra-thin (<5 nm) SiOxNyfilms. The nitrogen concentration and depth profiles were accurately determined by secondary ion mass spectrometry. It has been found that small amounts of nitrogen uniformly distribute in the dielectrics, and the kinetics of the oxynitridation (i.e., thickness vs. time) can be accurately expressed as a logarithmic equation. Meanwhile, the electrical properties of the oxynitride films: the average breakdown equivalent fields of dioxide (EBD), the breakdown time (TBD), the fixed charge (Qf), and the interface state density (Dit) have been characterized and analyzed by the current–voltage (I–V), the time-dependent dielectric breakdown, the capacitance–voltage (C–V), and the conductance–frequency (G–W), respectively. The oxynitride films with EBD ≈ 15.46 MV cm−1and TBD ≈ 2.39 E4ms were prepared successfully by processing optimization. The result reveals that the thermal low-pressure oxynitridation is helpful to obtain excellent gate dielectrics with low interface state density (Ditwith an order from 2.0 E9to 3.0 E10 ev−1 cm−2). Such a result can be attributed to nitrogen incorporation and slow growth rate during low-pressure processes. It is concluded that the characteristics of the oxynitride films are suitable for applications in metal-oxide-semiconductor and nonvolatile memory devices. [ABSTRACT FROM AUTHOR]