Subthreshold conduction

About: Subthreshold conduction is a research topic. Over the lifetime, 6343 publications have been published within this topic receiving 131957 citations. The topic is also known as: Subthreshold leakage.

Modeling of deep-submicrometer MOSFETs: random impurity effects, threshold voltage shifts and gate capacitance attenuation

Abstract: The authors present simulation results for the subthreshold characteristics of n-channel MOSFETs with 0.1 /spl mu/m gate-length and 0.05 /spl mu/m gate-width obtained with our 3D-DD simulator. We also presented a new method that one can successfully use in a particle-based simulator to properly account for the short-range portions of the e-e and e-i interactions without double-counting the long-range portions of these two interaction terms.

Subthreshold behavior of thin-film LPCVD PolySilicon MOSFET's

Abstract: A physical model that characterizes the subthreshold drain current (gate-voltage swing) and the threshold voltage of thin-film LPCVD polysilicon MOSFET's is developed and supported experimentally. The model describes the influence of the grain boundaries and of the charge coupling between the front and back gates on the subthreshold behavior. Main predictions are that the gate-voltage swing depends strongly on grain-boundary properties but weakly on the charge-coupling effects, that the threshold voltage depends strongly on grain-boundary properties and charge-coupling effects, and that the charge-coupling effects diminish as the grain-boundary trap density, the thickness of the film, or the doping density in the film increases. Comparisons of model predictions and measured data for passivated (hydrogenated) and unpassivated devices indicate quantitatively how hydrogenation reduces the trap density and increases the carrier mobility in the channel.

Modeling and sizing for minimum energy operation in subthreshold circuits

Abstract: This paper examines energy minimization for circuits operating in the subthreshold region. Subthreshold operation is emerging as an energy-saving approach to many energy-constrained applications where processor speed is less important. In this paper, we solve equations for total energy to provide an analytical solution for the optimum V DD and V T to minimize energy for a given frequency in subthreshold operation. We show the dependence of the optimum V DD for a given technology on design characteristics and operating conditions. This paper also examines the effect of sizing on energy consumption for subthreshold circuits. We show that minimum sized devices are theoretically optimal for reducing energy. A fabricated 0.18-μm test chip is used to compare normal sizing and sizing to minimize operational V DD and to verify the energy models. Measurements show that existing standard cell libraries offer a good solution for minimizing energy in subthreshold circuits.

Circuits and Methods for Characterizing Random Variations in Device Characteristics in Semiconductor Integrated Circuits

Abstract: Circuits and methods for measuring and characterizing random variations in device characteristics of semiconductor integrated circuit devices, which enable circuit designers to accurately measure and characterize random variations in device characteristics (such as transistor threshold voltage) between neighboring devices resulting from random sources such as dopant fluctuations and line edge roughness, for purposes of integrated circuit design and analysis. In one aspect, a method for characterizing random variations in device mismatch (e.g., threshold voltage mismatch) between a pair of device (e.g., transistors) is performed by obtaining subthreshold DC voltage characteristic data for the device pair, and then determining a distribution in voltage threshold mismatch for the device pair directly from the corresponding subthreshold DC voltage characteristic data. The voltage threshold mismatch distributions of different device pairs of a given circuit design can then be used to determine voltage threshold variations of the constituent circuit devices. The voltage threshold variation of the devices can be used to characterize the random variations of the given circuit.