Threshold Voltage Instability and Low Frequency Noise in Hafnium-Based Gate Dielectrics

摘要

This paper focus on two of the main reliability problems observed in Hafnium-based gate dielectrics: threshold voltage instability and low frequency noise. Both issues are ascribed to the Hf-Si bonds generated at the HfO{sub}2/polysilicon interface. These defects act as charge capture centers whose trapping probability decreases with the inverse of the number of injected charges. In the case of HfO{sub}2/polysilicon gate stack the drain low frequency noise increases of two orders of magnitude and the gate low frequency noise increases of three orders of magnitude with respect to SiO{sub}2/polysilicon gate stack. By using HfSiON as gate dielectrics or metal as gate electrode both reliability problems are strongly reduced.