Variability analysis of scaled poly-Si channel FinFETs and tri-gate flash memories for high density and low cost stacked 3D-memory application

The threshold voltage (V_t) in scaled poly-Si channel FinFETs and tri-gate flash memories with poly-Si floating gate (FG) was systematically compared with crystal channel ones, for the first time. It was found that some superior I_d-V_g characteristics are observed in the scaled poly-Si channel FinFETs with gate length (L_g) down to 54 nm or less. The standard deviation of V_t (σV_t) of poly-Si channel FinFETs was 3 times higher than that of crystal channel ones at the same gate oxide thickness (T_ox). However, the σV_t of poly-Si channel tri-gate flash memories after one program/erase (P/E) cycle became comparable to that of crystal channel ones. Moreover, it was found that punch-through voltage of the poly-Si channel tri-gate flash memory is as high as 4.6 V even L_g was down to 76 nm.