Electrical properties of high-quality ultrathin nitride/oxide stack dielectrics

The electrical properties of ultrathin nitride/oxide (N/O) stack dielectrics (2-4 nm), produced by in-situ jet vapor deposition (JVD), have been studied in some detail. Both theoretical calculation and experimental data show that the leakage current in the N/O stack is substantially lower than that in the single oxide layer of the same equivalent oxide thickness (EOT). When compared to the single nitride layer, the N/O stack yields a lower leakage current in the 3-nm thickness regime. In the 2-nm thickness regime, however, the leakage currents in the single nitride layer and the N/O stack are comparable. The tunneling current in the N/O stack depends not only on the thickness combination of the nitride and the oxide layers, but also on the injection polarity. Other important electrical properties of the N/O stack, including time-dependent-dielectric-breakdown (TDDB), stress-induced leakage current (SILC), carrier trapping, and interface characteristics are also reported. High quality field-effect transistors have been made of the N/O stack, and their properties will be reported