Investigation of Data Pattern Effects on Nitride Charge Lateral Migration in a Charge Trap Flash Memory by Using a Random Telegraph Signal Method

Abstract

Data pattern effects on nitride charge lateral migration and V-t retention loss in a charge trap flash memory is investigated. We use channel hot electron program and band-to-band tunneling hot hole erase to inject different amounts of electrons and holes at the two sides of a channel in a SONOS cell. An interface oxide trap near an injected charge packet and its associated random telegraph signal (RTS) are used as an internal probe to detect a local channel potential change resulting from trapped charge lateral migration. Vt retention loss and RTS in various charge storage patterns are characterized and analyzed. At a similar built-in electric field, nitride trapped holes are found to be more mobile than trapped electrons in lateral migration.