Two-dimensional polysilicon quantum-mechanical effects in double-gate SOI

Important quantum-mechanical poly quantization effects are demonstrated that reduce inversion capacitance and accentuate short-channel (DIBL) effects in fully depleted double gate SOI devices. Without considering the polysilicon quantization effects, /spl sim/20% over-estimated gate capacitance is predicted with L/sub g/ = 20 nm, t/sub si/ = 5 nm and t/sub ox/ = 1 nm. The polysilicon quantization effect is shown to be enhanced by the drain bias, which implies that DIBL of double-gate SOI is significant due to these effects. The QM effects become worse with increased gate doping, implying ultimate limitations in using polysilicon gates for sub-20 nm DG/FD SOI. Even highly-doped polysilicon gates degrade device performance for sub-20 nm DG/FD SOI due to the polysilicon quantization effects, just as low-doped polysilicon gates degrade performance due to polydepletion effects.