Characteristics of oxide breakdown and related impact on device of ultrathin (2.2 nm) silicon dioxide

Abstract

The oxide breakdown characteristics of ultrathin oxide (2.2 nm) have been studied in this paper. Light emission microscopy (EMMI) analysis shows that each breakdown has a specific failure location with a random distribution. Gate leakage current increases for all soft breakdown events are similar. After soft breakdown, the I-V curve still shows the representative direct tunneling characteristics and can be fitted using a dual direct tunneling (DDT) model. Soft breakdown has no effect on the drain current of long-channel devices. Breakdown at the polyedge appears to be of the hard-breakdown mode and results in an abrupt increase in gate current. For short-channel devices, the polyedge is always within the damaged region of an oxide because the channel is shorter than the damaged region of the oxide. Hence, only hard breakdown resulting in permanent damage is observed in short-channel devices.