부산대학교 도서관

We investigate the sensitivity of silicon–oxide–nitride–silicon–oxide (SONOS) charge trapping memory technology to heavy-ion induced single-event effects. Threshold voltage ( $V_{T}$ ) statistics were collected across multiple test chips that contained in total 18 Mb of 40-nm SONOS memory arrays. The arrays were irradiated with Kr and Ar ion beams, and the changes in their $V_{T}$ distributions were analyzed as a function of linear energy transfer (LET), beam fluence, and operating temperature. We observe that heavy ion irradiation induces a tail of disturbed devices in the “program” state distribution, which has also been seen in the response of floating-gate (FG) flash cells. However, the $V_{T}$ distribution of SONOS cells lacks a distinct secondary peak, which is generally attributed to direct ion strikes to the gate-stack of FG cells. This property, combined with the observed change in the $V_{T}$ distribution with LET, suggests that SONOS cells are not particularly sensitive to direct ion strikes but cells in the proximity of an ion’s absorption can still experience a $V_{T}$ shift. These results shed new light on the physical mechanisms underlying the $V_{T}$ shift induced by a single heavy ion in scaled charge trap memory.