Investigation of Discrete Dopant Fluctuation Effects in Sub-45-nm Silicon–Oxide–Nitride–Oxide–Silicon Flash Memory Cell

Abstract

The effects of discrete dopant fluctuation in sub-45-nm silicon–oxide–nitride–oxide–silicon (SONOS) flash memory cells are studied for the first time. In addition to the well-known fluctuation in threshold voltage, the wide threshold voltage distribution also affects cell retention, which results in a severe reliability problem in planar SONOS flash memory cells beyond the 22 nm generation. Similar discrete dopant effects are observed in the fin field-effect transistor (FinFET) structure. The FinFET SONOS flash memory cell having a nearly un-doped channel is shown to be promising for sub-22-nm SONOS technologies.