Non-quasi-static modeling/implementation of BJT current crowding for seminumerical mixed-mode device/circuit simulation

VLSI technology CAD (TCAD) requires integrated, physics-based tools for predictive process, device, and (small-scale) circuit simulation. Computational efficiency is desirable, and indeed essential if the TCAD system is to be used in manufacturing CAD involving statistical simulation. Conventional TCAD systems comprise robust, numerical process and device simulators which drive optimization of empirical device model parameters for circuit simulation. This optimization can miss parametric correlations, and hence the integrated system, although CPU-intensive, could yield non-unique (erroneous) predictions. Numerical mixed-mode device/circuit simulation would obviate this deficiency, but with a high cost of computation time. Alternatively, improvement of the TCAD system can possibly be afforded by incorporation of semi-numerical device models into the circuit simulator which have physical parameters that relate directly to the device structure. The resulting tool is an application-specific, computationally efficient mixed-mode simulator that can easily be integrated with the process simulator by a program that evaluates the model parameters firom the doping profile. We are developing such a simulator (MMSPICE), and the program (SUMM) which integrates it with SUPREM-3.