Physical Mechanism of High-Programming-Efficiency Dynamic-Threshold Source-Side Injection in Wrapped-Select-Gate SONOS for NOR-Type Flash Memory

Abstract

For the first time, a programming mechanism for conventional source-side injection (SSI) (normal mode), substrate-bias enhanced SSI (body mode), and dynamic-threshold SSI (DTSSI) (DT mode) of a wrapped-select-gate SONOS memory is developed with 2-D Poisson equation and hot-electron simulation and programming characteristic measurement for NOR Flash memory. Compared with traditional SSI, DTSSI mechanisms are determined in terms of lateral acceleration electric field and programming current (I(PGM)) in the neutral gap region, resulting in high programming efficiency. Furthermore, the lateral electric field intersects the vertical electric field, indicating that the main charge injection point is from the end edge of the gap region close to the word gate.