An advanced equation assembly module

We present an advanced equation assembly module which has been developed for the simulation of semiconductor devices based on the Finite Boxes discretization scheme and is currently used in the general purpose device and circuit simulator MINIMOS-NT. Such simulations require the solution of a specific set of nonlinear partial differential equations which are discretized on a grid. The resulting nonlinear problem is solved by a damped Newton algorithm that demands the solution of a linear equation system at each step. The presented module is responsible for assembling these systems and takes into account several requirements of the simulation process. The underlying concepts, namely the representation of boundary conditions, physically motivated variable transformation, preelimination and numerical conditioning, are presented together with some examples.