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. © 2009 The Japan Society of Applied Physics.