Temperature-accelerated breakdown in ultra-thin SiON dielectrics

Abstract

The temperature-dependent breakdown of silicon oxynitride gate dielectrics was studied to determine their reliability at and above operating temperatures. This paper demonstrates that the Weibull slopes of the ultra-thin layers are temperature dependent in the range from room temperature to 200 °C, and furthermore different behaviour is observed for pmos and nmos structures, with pmos structures not suffering any reliability loss at elevated temperature. We highlight that the improved reliability may simply be related to the problem of detecting the ‘real’ breakdown in the layers. Further to this we find an interesting effect where temperature and voltage can be used interchangeably to stress an oxide, and propose a method of normalizing stress data collected at a number of stress temperatures to one reference temperature. The findings support a voltage-dependent voltage acceleration.