Dielectrically isolated high-voltage power devices

High voltage power devices in dielectrically isolated (Dl) structure for power integrated circuits (PICs) applications have been proposed in this research by extending the REduced SURface electric Field (RESURF) principle of junction isolation (JI) technology. With the new DI RESURF technique, thin silicon layer DI wafers made by the direct-wafer-bonding (DWB) method have been utilized successfully to fabricate various lateral high voltage power devices. JI devices were simultaneously fabricated and their characteristics were compared to the new DI device structures.; Extensive two-dimensional computer simulations and analytic derivation were performed to obtain relationship of the breakdown voltage to major DI structure parameters such as silicon layer thickness, isolating oxide thickness, drift region doping concentration, and drift region length. Experimental results showed that breakdown voltages over 700 volts could be obtained in lateral p-i-n diode structure.; The high voltage lateral insulated gate bipolar transistor (LIGBT) has been investigated as a demonstration of the DI RESURF principle. Three different LIGBT collector structures were studied. These are the conventional collector with n-buffer layer, a shorted-collector, and a hybrid Schottky collector. Higher forward voltage drop in all three collector structures of DI devices were found compared to the JI case, but the switching speed of the DI devices was observed to be faster by an order of magnitude. The cause of these differences is due to the additional current flow that occurs into the substrate in the JI devices. With shorter turn-on pulse width, the turn-off time was greatly reduced as verified by measurement. In comparison with JI devices, DI'S have superior trade-off performance.; The lateral emitter switched thyristor (LEST), a new lateral MOS-gated device, was analyzed, designed, and fabricated in DI and JI technologies with three anode constructions. Two basic LESTs, the conventional and dual channel structures, were studied. The breakdown voltage of DI LESTs attained could be predicted by DI RESURF principle. Analogous to LIGBTs, the forward voltage drop of DI LESTs was slightly higher than that of JI devices, and DI's were faster in switching speed. High voltage current saturation has been observed up to 200 V in dual channel LEST. However, forward characteristic of dual channel LEST were slightly poorer than the conventional LEST due to the space needed for second channel. In addition, LESTs only showed comparable dc and switching characteristics to LIGBTS. This is attributed to a larger cell area required for incorporating the floating cathode in LEST structure and a considerable part of current flow through the MOSFET channel in LEST.