A Comparison of the Mobility Models Defining MOSFET Threshold Voltage for Low Temperatures

Abstract

Accurate Technology Computer-Aided Design (TCAD) modeling of silicon integrated circuits (ICs) and semiconductor devices for cryogenic temperatures requires well-calibrated models of electrical parameters. One of these most important parameters is the mobility of charge carriers. In this paper, the mobility models used in TCAD Sentaurus and TCAD Silvaco were analyzed. Using various models, the temperature dependences of the threshold voltage were calculated for an n-channel metal-oxide-semiconductor field-effect transistor (M OSFE T) with a channel length of 1 μm, The contribution of various mobility models to this relationship has been evaluated. The work considered three models of bulk mobility, two models of mobility in an inverse layer, three models of carrier-carrier scattering and one model of mobility in strong electric fields. Comparison with experimental data showed that the main models are the mobility in the inverse layer and bulk mobility. Carrier-to-carrier scattering models do not affect the threshold voltage value. The contribution of the mobility model in strong electric fields is small. As a result, the models that give the most accurate value of the threshold voltage were identified.