US Patent 7355226 Power semiconductor and method of fabrication

This invention is generally concerned with power semiconductors such as power MOS transistors, insulated gate by bipolar transistors (IGBTs), high voltage diodes and the like, and method for their fabrication. A power semiconductor, the semiconductor comprising a power device, said power device having first and second electrical contact regions and a drift region extending therebetween; and a semiconductor substrate mounting said device; and wherein said power semiconductor includes an electrically insulating layer between said semiconductor substrate and said power device, said electrically insulating layer having a thickness of at least 5 μm.