iSIM: Ultra-deep submicron MOSFET physical model for analog and low power digital circuits

The goal of the research presented in this thesis is to remove various shortcomings in existing short-channel MOSFET models and to extend the scope and applicability of the deep-submicron MOSFET model down to the future 0.1 $\mu$m Si technology. As the device dimensions shrink and the scale of integration grows considerably, a more accurate, physical, and efficient model has been in strong demand to account for the device characteristics in the circuit simulation. In particular, since the design trend for ULSI circuits and systems has been moving toward mixed analog-digital low power chips, the modeling strategy has been changed to accurately model the weak and moderate inversion regions with a single equation model and with a continuous and smooth characteristics near all the device-operation boundaries. Furthermore, the charge (capacitance) modeling has become significantly important, while very little attention has been paid to the C-V characteristics for over 20 years.iSIM (illinois Short-Channel IGFET Model) is a new physical model developed with emphasis on deep-submicron technology effects such as the nonuniform substrate doping, mobility reduction due to several scattering mechanisms, carrier velocity saturation, drain-induced barrier lowering, channel-length modulation, lightly doped drain device, and source-to-drain series resistance. For analog circuit applications, not only the weak and moderate inversion characteristics, but also small-signal AC capacitances have been modeled accurately with a single equation for both DC and AC models in iSIM. Comparisons of iSIM results with measured I-V characteristics of state-of-the-art MOS transistors from industry show an excellent fit for both long channels and short channels down to about a quarter micron.For an ultrasmall device below 0.25 $\mu$m, the nonlocal stationary carrier transport effect becomes significantly important. The effect results in increased current-driving capability over what is expected for stationary carrier transport theory. The accurate and compact model presented in this thesis includes the nonlocal stationary carrier transport effect and is a first model which can accurately predict the characteristics of an ultrasmall device below 0.25 $\mu$m. The model is computationally inexpensive and predictive and enables designers to obtain quick and accurate estimates of the performances of their future generation technology.iSIM has been implemented in SPICE3 and tested with many benchmark circuits. In all benchmark tests, iSIM shows an excellent convergence characteristic due to the continuous and smooth characteristics of our model equation.U of I OnlyETDs are only available to UIUC Users without author permissio