Study of interface degradation of Hf-silicate gate dielectrics during thermal nitridation process

An evaluation of the effect of nitridation temperature on interface layer (IL) quality of Hf-silicate gate dielectric prepared by the atomic layer deposition method has been reported. An increase in IL density and IL roughness was observed by x-ray reflectivity as the nitridation temperature was increased. X-ray photoelectron spectroscopy showed preferential interface reaction at the dielectric-Si interface at higher temperatures. The progressive increase in IL roughness finally led to degradation of the breakdown voltage, a shift in flat band voltage (∼0.54 V), and deterioration of electron channel mobility by ∼20% in samples nitrided at 850 °C.