The power semiconductor devices control the energy flow in virtually every electric and electronic system. Most common applications are: automotive, traction, consumer electronics, air conditioning, electric engines. The improvement in power devices results in improved power management circuits with increased efficiency. Reduced environmental pollution, reduced cost, reduced size, and longer battery life are only few of the advantages that derive from advancements in the design of power semiconductor devices. Dating from the invention of the transistor, a continuous research and development activity, driven by the huge market request, provided new device concepts, advanced design techniques, and new materials that largely improved the performance of the power semiconductor devices. A big step towards the ideal device is the introduction of the SuperJunction (SJ) in 1997 with inherent drastic reduction of the ON state resistance and of the conduction losses for power devices. SJ is not an improvement due to the use of a new material. It is an improvement derived by an innovative design technique for the sustaining layer that, instead of exhibiting a one dimensional structure, is manufactured with a complex two or three dimensional structure. SJ design technique is therefore applicable to many power devices but requires a design approach that differs from the one used for conventional power devices.