Thermal stability of TaSixNy films deposited by reactive sputtering on SiO2

The thermal stability of TaSixNy/SiO2/p-type Si metal-insulator-semiconductor structure has been evaluated by measuring equivalent oxide thickness (EOT) from capacitance-voltage curves and gate leakage current as a function of annealing temperatures. TaSixNy films were deposited using reactive sputtering from a TaSi2 target, varying the nitrogen/argon flow ratio. A reaction between Ta53Si47 and SiO2 was observed after a 1000degreesC anneal, resulting in the increase of interfacial roughness and oxide thickness in the TaSixNy/SiO2/p-Si structures. Cross-sectional transmission electron microscopy shows no indication of an interfacial reaction or crystallization in Ta22Si29N49 on SiO2 up to 1000degreesC as manifested by the negligible change in EOT and the stable leakage currents density (2.0x10(-6) A/cm(2) at V-g=-1 V). The presence of Si-N bonds is attributed to cause the amorphous nature of the high N-containing TaSixNy films. This may retard the formation of an interface layer and improve the chemical-thermal stability of the gate electrode/dielectric interface and oxygen diffusion barrier properties under high-temperature annealing. (C) 2003 The Electrochemical Society.