Drain leakage current characteristics due to the band-to-band tunneling in LDD MOS devices

Drain leakage current characteristics due to band-to-band tunneling in very thin-gate-oxide LDD (lightly doped drain) MOSFETs are described. It is shown that the electrical characteristics of LDD devices strongly depend on complicated generation regions of the band-to-band tunneling current. Effects of sidewall oxidation and LDD concentrations on this leakage current have been clarified using measured data and a newly developed numerical model for the band-to-band tunneling. A novel dependence of subbreakdown voltage on LDD concentrations is found, and then related to the generation regions of the band-to-band tunneling. The gate bird's beak is more effective in suppressing the gate-induced drain leakage current in low-concentration LDD devices than in high-concentration devices.<
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