Reliability of ultra-thin oxides in CMOS circuits

Hyper-thin films (~1nm or thinner) of SiO2 or silicon oxynitride continue to be a critical component as the gate insulator in high-performance MOSFETs or as the interfacial layer in high-k stacks for low power applications. Controversy remains over the physical interpretation as well as the application of breakdown data, but there is general agreement that the reliability margin for hyper-thin oxide is greatly diminished compared to thicker films, if the time of first breakdown is assumed to correspond to product failure. However, the last few years have seen some new understanding of the breakdown process, and renewed attention to the actual effect of oxide breakdown on circuit performance, which may permit an improved reliability outlook. In this paper we review oxide reliability projections and discuss current topics such as progressive breakdown and implications for circuits.