Design methodology and simulation tool for floating ring termination technique

A new methodology to optimize the design of floating ring (FR) termination technique for high voltage device is presented. The basic idea is to simulate the blocking capability of the structure with only one guard ring and then extend the results to a multiple FR system. A second advantage of our method is to include the ring width in the optimization process. The effectiveness and efficiency of our methodology is illustrated by optimizing a FR structure with a junction depth x(j) = 5 mu m and Si substrate doping 2.10(14) cm(-3). A seven rings structure is optimized giving 85% efficiency in respect to the ideal plane parallel junction breakdown voltage V-BD = 840 V. The simulation results are generated by the user-oriented simulation program POWER2D for studying the voltage handling capability of arbitrary shaped power semiconductor devices. A special algorithm is implemented ensuring very fast and automatic search of the breakdown via the ionization integrals calculus. An efficient numerical algorithm to drastically reduce the number of iterations when adjusting the quasi-fermi potential of the floating rings has also been developped. (C) 1998 Elsevier Science Ltd. All rights reserved.