On the impact of mechanical stress on gate oxide trapping

Abstract

The electrical performance and reliability of MOSFETs and charge-trap flash memories are influenced by the traps in the gate dielectric. Trap properties depend on the atomic structure of the dielectric and are thus expected to be affected by mechanical stress, which modifies the bonds between atoms. Consequently, the mechanical stress, either engineered or created as a side effect of fabrication, needs to be considered in order to improve the device performance and reliability. This work demonstrates a systematic and controlled experimental study of the trapping process in individual gate oxide defects under externally applied mechanical stress. The significant and reversible impact of the mechanical stress on the trapping behavior is demonstrated and a theory to explain the observations is proposed.