A Predictor/CAD Model for Buried-Channel MOS Transistors

An analytical predictor/CAD model for a short-channel buried-channel MOSFET is reported. The proposed model can be used to predict the anomalous threshold voltage shift associated with the short-channel buried-channel MOSFET. The characteristic is shown to be caused by the shifting of the operational mode from the surface to the buried channel. Current equations which are applicable to the short-channel buried-channel device are derived. For the purpose of circuit simulations, a computationally efficient CAD current model is also developed. The current characteristics calculated from the model equation are found to be in good agreement with experimental results. By using the CAD current equations, a charge model for the intrinsic buried-channel device is formulated. The charge model equations can be used to model the intrinsic capacitances for SPICE simulations.