Characteristics of TaOxNy gate dielectric with improved thermal stability

We report the properties of novel gate dielectric TaOxNy prepared by low-pressure chemical vapor deposition using Ta(OC2H5)(5) and NH3. The metal-oxide-semiconductor (MOS) characteristics of TaOxNy/SiO2 gate dielectric are compared with those of Ta2O5/SiO2 stack gated with a W/WN electrode. The flat-band voltage shift (DeltaV(1b)) of TaOxNy in comparison with Ta2O5 is -0.17 V due to the nitrogen-induced positive charges accumulated at the SiO2/Si interface. The interface state density of W/WN/TaOxNy/SiO2/p-Si nMOS capacitors as determined by the conductance method is in the 0.85-1.5 x 10(11) eV(-1) cm(-2) range near the Si midgap. The leakage current level of the TaOxNy/SiO2/p-Si MOS capacitor is similar to - 10nA/cm(2) at -2.5 V at the effective oxide thickness (T-ett) of 31 Angstrom. The leakage current is four to five orders of magnitude lower than that of poly-Si-gated SiO2 in the -2- - 3 V range. The reliable characteristics of TaOxNy over Ta2O5 in terms of a smaller increase in T-eff and excellent breakdown field against selective oxidation at 950 degreesC allow us to maintain the standard complementary metal-oxide-semiconductor fabrication process and technology.