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

Abstract

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 V-th shift but without subthreshold slope degradation. However, charge pumping current (I-CP) 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 N-it located SiO2/Si has insignificant degradation due to reduction in stress electric field. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752456]