Comparative study of tri-gate- and double-gate-type poly-Si fin-channel split-gate flash memories

The tri-gate (TG)- and double-gate (DG)-type poly-Si fin-channel split-gate flash memories with a thin n
⁺
-poly-Si floating-gate (FG) have successfully been fabricated, and their electrical characteristics including the variations of threshold voltage (Vt) and S-slope have been comparatively investigated. It was experimentally found that better short-channel effect (SCE) immunity, smaller V
_t
variations, and a higher program speed are obtained in the TG-type flash memories than in the DG-type memories. Moreover, it was also confirmed that over-erase is effectively suppressed by split-gate structure.