2. D-MOSFET Structure

The first power MOSFET structure commercially introduced by the power semiconductor industry was the double-diffused or D-MOSFET structure. The channel length of this device could be reduced to sub-micron dimensions by controlling the diffusion depths of the P-base and N⁺ source regions without resorting to expensive lithography tools [1]. The device fabrication process relied up on the available planar gate technology used to manufacture CMOS integrated circuits. These devices found applications in power electronic circuits that operated at low (<100 V) voltages. The fast switching speed and ruggedness of the D-MOSFET structure were significant advantages compared with the performance of the available bipolar power transistor.