Accuracy and validation issues for the simulation of power semiconductor devices

CAE techniques, although widely used in the design and manufacture of VLSI devices, have so far failed to make much impact on power device technology. Important features such as switching performance and non uniform behaviour are typically difficult to study using standard device simulation packages. Common assumptions used in the discretisation of the semiconductor device equations are shown to have serious shortcomings when applied to typical power structures. Techniques for error estimation and validation are discussed. Comparison of the results of GTO thyristor turn-off simulations performed on fixed and adaptive meshes demonstrate the importance of choosing the correct discretised mesh. It is concluded that the accurate modelling of power devices requires a consistent formulation of the semiconductor device equations, adaptive meshing and a reliable means for validation of the results