Accurate Threshold Voltage Measurement for Use with SOISPICE

The thin-film nature of silicon on insulator (SOI) material complicates considerably the extraction of accurate threshold voltage (VTf) values. This work assesses the accuracy of the standard VTf extraction techniques and presents an alternative method, independent of series resistance, with improved accuracy. The improved accuracy of the threshold voltage measurement enables physical parameters such as flatband voltages and oxide thicknesses to be calculated more accurately. As SOI technology is an important contender for low voltage/low power, high temperature and ULSI circuit applications it is imperative to have an established, accurate modelling facility such as SOISPICE. We show that our method of measuring VTf is compatible with SOISPICE. Simulation results show that using an inappropriate VTf extraction technique can cause significant errors in the transient response of SOI circuits at low voltages.