A comparative study of depth profiling of interface states using charge pumping and low frequency noise measurement in SiO 2/HfO 2 gate stack nMOSFETs

Abstract

Charge pumping and low frequency noise measurements for depth profiling have been studied systematically using a set of gate stacks with various combinations of IL and HfO 2 thicknesses. The distribution of generated traps after HCI and PBTI stress was also investigated. The drain-current power spectral density made up all of the traps of IL in 0 < z < T IL and the traps of HfO 2 in T IL < z < T HK. The traps near the Si/SiO 2 interface dominated the 1/ f noise at higher frequencies, which is common in SiO 2 dielectrics. For the HfO 2/SiO 2 gate stack, however, the magnitude of the 1/ f noise did not significantly change after HCI and PBTI because of more traps in the bulk HfO 2 film than at the bottom of the interface.