4. SC-MOSFET Structure

As discussed in Chap. 2, the first power MOSFET structure commercially introduced by the power semiconductor industry was the D-MOSFET structure with the planar gate architecture. The fast switching speed and ruggedness of the D-MOSFET structure were significant advantages compared with the performance of the available bipolar power transistor. In order to reduce the specific on-resistance of the structure, the planar gate topology was replaced with a trench gate topology in the 1990s by creating the power U-MOSFET structure. The significant reduction of the specific on-resistance achieved using this approach has been described in Chap. 3. It has been found that the high input capacitance and large gate transfer charge for the power U-MOSFET structure offsets the benefits of the low specific on-resistance in high frequency applications such as the voltage-regulator-modules (VRMs) used to provide power to microprocessors.