Experimental and theoretical investigation of nonvolatile memory data-retention

Abstract

Data retention is one of the main issues affecting nonvolatile memory reliability due to the critical single-cell internal dimension scaling down. In this paper an extensive investigation of floating-gate memory charge retention is presented. We argue that the retention time, namely log(t/sub R/), varies linearly with temperature T rather than with 1/T as commonly assumed, yielding a drastic reduction in the extrapolated time-to-failure. The experimental evidence of the new "T Model" is proved by means of several experimental results. The physical consistency of the "T Model" is shown to reside in the temperature exponential behavior of the Fowler-Nordheim current. Indeed, a good physical modeling of both experimental current-temperature (J-T) and memory retention characteristics is achieved. Finally, it is shown that this new "T Model" reconciles seemingly controversial activation energy data from the literature.