A Simple and Unambiguous Definition of Threshold Voltage and Its Implications in Deep-Submicron MOS Device Modeling

X. Zhou, Member, IEEE, K. Y. Lim, Student Member, IEEE, and D. Lim

Figures

Fig. 1 | Fig. 2 | Fig. 3 | Fig. 4

Fig-1

Fig. 1 Critical drain current (circle) measured at Vgs = Vt0 against drawn gate length, where Vt0 is the linear threshold voltage based on the maximum-gm definition.  Constant current (triangle) is also plotted as a comparison.  The inset shows the same data on a log-log scale.

Fig-2

Fig. 2 Ids - Vgs curves in saturation (Vds = 2.5 V) for different gate-length devices as indicated.  The critical currents and the corresponding threshold voltages are shown in symbols for the “Icrit@Vt0” definition (circle) and the CC definition with Id0 = 0.1 µA (triangle) and 1 µA (square).

Fig-3

Fig. 3 Measured saturation threshold voltages against drawn gate length for the “Icrit@Vt0” definition (circle), the CC definition with Id0 = 0.1 µA (triangle) and 1 µA (square), and the quadratic-extrapolation definition (diamond).

Fig-4

Fig. 4 Gate voltage shift due to a change in DVds = (0.1 - 2.5) V measured at different drain currents for three transistors with Lg = 3, 0.5, and 0.2 µm.