Soft breakdown of hafnium oxynitride gate dielectrics

Abstract

A detailed study of soft breakdown modes for hafnium oxynitride (HfON) gate dielectrics under stress is investigated. Two types of soft breakdown, digital and analog modes, are observed in HfON gate dielectrics, featuring gate voltage fluctuation accompanying random telegraph noise and nonswitching 1/f noise, respectively. The dependence of gate area, oxide thickness, and stress current density on breakdown modes is also studied. Thin oxide thickness and small gate area contribute to the enhancement of charge to breakdown (Q(bd)). Large Joule heat damage generated under stress inducing the analog soft breakdown for thick hafnium oxynitride films is proposed to clearly understand the breakdown of HfON gate dielectrics. (c) 2005 American Institute of Physics.