Doping Profile Optimization for Power Devices Using Topology Optimization

This paper proposes an optimization method with a high degree of freedom for the doping profile optimization of power devices. In this method, which is based on topology optimization, the design domain is divided into many elements, and the doping or dose densities of all of the elements are taken as the design variables to be optimized. An optimal structure is obtained by repeatedly modifying a given structure using mathematical programming. The proposed optimization method was applied to two design problems. First, the tradeoff between the breakdown voltage and ON-resistance was optimized for a p-n diode by using a function of the electric field strength as the objective function under a constraint to the ON-resistance. Second, for a junction termination extension structure, a robust optimization method considering the ion implantation process was applied to prevent the concentration of the electric field by dose fluctuation. The numerical results from these two problems demonstrate that the proposed method can be effectively used to derive an improved doping profile for power devices.