Abnormal interface state generation under positive bias stress in TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors

This Letter studies positive bias stress-induced abnormal interface state on TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors. It can be found that the degradation is associated with electron trapping, resulting in Vth shift but without subthreshold slope degradation. However, charge pumping current (ICP) shows a significant degradation after stress. Accordingly, the impact ionization-induced Nit located HfO2/SiO2 is proposed to demonstrate the ICP degradation. The AC stress with several frequencies is used to evidence the occurrence of impact ionization. Further, the device with additional pre-existing Nit located SiO2/Si has insignificant degradation due to reduction in stress electric field.