Philips NatLab – On Compact Models for High-voltage MOS Devices #SWI1999

Fast evaluation of integrated circuits(ICs) requires the availability of so-called compact models, i.e. simple-to-evaluate relations between the voltages and the currents in the IC-components. In this paper, the compact model for a particular IC-part, the LMDOS device, is studied. This model consists of coupled submodels, each of which describes a separate part of the LDMOS device. The purpose of the present work is the derivation of the submodel for the transition region of the LDMOS. As a preparation, a model for a neighboring region, the drift region, is derived in full detail. It is shown that the submodels for transition and drift regions are very similar, although the transition region seems to be more intricate as far as its geometry is concerned. The general form of the transition region model needs an evaluation of an integral. The expression can be reduced to an algebraic one if the voltages applied to the boundaries do not differ much. This insight may enhance the evaluation speed considerably.