Improvement in electrical properties of hafnium and zirconium silicates by postnitriding

Hafnium and zirconium silicate films were deposited on a silicon substrate and the effects of postannealing on their electrical properties were investigated. When the films are postannealed in nitrogen monoxide (NO), the leakage current becomes lower by more than one order of magnitude as compared with that of the as-deposited films. The capacitance-voltage (C-V) hysteresis width is also decreased drastically by the NO postannealing. From electron spin resonance spectroscopy, it is indicated that paramagnetic defects at the interface between the film and the substrate are responsible for the leakage current and the C-V hysteresis. It is also indicated by x-ray photoelectron spectroscopy that the postnitridation effectively terminates these interface defects and contributes to the improvement in electrical properties.