OXIDE WEAROUT, BREAKDOWN, AND RELIABILITY

Abstract

The subject of oxide wearout, breakdown, and reliability will be reviewed, largely, from an historical perspective. Five topics will be discussed: oxide breakdown, oxide leakage currents, trap generation, statistics, and reliability. An early model of oxide breakdown, developed by Klein and Solomon, will be described and will be shown to be generally applicable to oxide manufactured today, and to other solid insulators, as well. Both hard and soft breakdown were included in this model and will be discussed here. The importance of stress-induced-leakage-currents (SILCs) and direct tunneling currents will be discussed in the context of device applications, thinner oxides, and oxide reliability. The diminishing importance of breakdown in ultra thin oxides in ultra small devices will be contrasted with the increasing importance of oxide leakage currents. Trap generation is important in the triggering of breakdown and in the formation of SILCs. Trap generation will be discussed in some detail. Various statistical formulations of oxide breakdown, and how these distributions are related to trap generation, will be discussed. All of these effects will be related to oxide reliability and oxide integrity. An extensive bibliography has been included to help the reader obtain more detailed information concerning the concepts being discussed.