Characteristics of TaOxNy gate dielectric with improved thermal stability

We report the properties of novel gate dielectric TaOxNy prepared by low-pr essure chemical vapor deposition using Ta(OC2H5)(5) and NH3. The metal-oxid e-semiconductor (MOS) characteristics of TaOxNy/SiO2 gate dielectric are co mpared 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 -0.1 7 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 capac itors as determined by the conductance method is in the 0.85-1.5 x 10(11) e V(-1) cm(-2) range near the Si midgap. The leakage current level of the TaO xNy/SiO2/p-Si MOS capacitor is similar to - 10nA/cm(2) at -2.5 V at the eff ective 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 o f a smaller increase in T-eff and excellent breakdown field against selecti ve oxidation at 950 degreesC allow us to maintain the standard complementar y metal-oxide-semiconductor fabrication process and technology.