Numerical confirmation of inelastic trap-assisted tunneling (ITAT) as SILC mechanism

Abstract

This paper presents a quite comprehensive procedure covering both the stress-induced leakage current (SILC) and oxide breakdown, achieved by balancing systematically the modeling and experimental works. The underlying model as quoted in the literature features three key parameters: the tunneling relaxation time /spl tau/, the neutral electron trap density N/sub t/, and the trap energy level E/sub t/. First of all, 7-nm thick oxide MOS devices with wide range oxide areas are thoroughly characterized in terms of the optically induced trap filling, the charge-to-breakdown statistics, the gate voltage developments with the time, and the SILC I-V. The former three are involved together with a percolation oxide breakdown model to build N/sub t/ explicitly as a function of the stress electron fluence. Then the overall tunneling probability is calculated, with which a best fitting to SILC I-V furnishes /spl tau/ of 4.0/spl times/10/sup -13/ s and E/sub t/ of 3.4 eV. The extracted /spl tau/ is found to match exactly that extrapolated from existing data. Such striking consistencies thereby provide evidence that inelastic trap-assisted tunneling (ITAT) is indeed the SILC mechanism. Differences and similarities of the involved physical parameters between different studies are compared as well.