Abstract
Abstract Critical design issues for 4H-SiC lateral devices on a semi-insulating substrate with a RESURF structure have been investigated and verified through simulation and experiment. The dependence of breakdown voltage on surface charges, field plates, and charge imbalance conditions was simulated. From simulation results, it is evident that the field plates help reducing the electric field crowding and the surface charges play a critical role in the charge imbalance analysis. Compared to single zone, a two-zone RESURF structure is able to create an additional peak in the electric field profile, thus increasing the Breakdown Voltage ( BV) from 5880 to 8000 V for a device with a drift region length of 100 μm. The lateral High-Voltage devices on semi-insulating substrate including PN diode, JFET, MOSFET, and IGBT were fabricated and characterized to verify the advantages of the proposed structure. Various process improvement, such as N2O annealing, lifetime enhancing, was also done to better the forward characteristic. To check the feasibility of integrating High-voltage with low-voltage devices on a chip, a CMOS inverter was fabricated and tested. The main achievements of this study are (1) The two-zone lateral JFET with Ld of 100 μm exhibits a specific on-resistance of 454 mΩ-cm2 and a BV of 4200 V, having a figure of merit of 38.8 MW/cm2. (2) The single-zone lateral MOSFET with Ld of 40 μm shows a Ron,sp of 115 mΩ-cm2 and a BV of 2460 V. The FOM is as high as 52 MW/ cm2. (3) A 4H-SiC lateral High-Voltage IGBT on semi-insulating substrate is demonstrated for the first time. An Ron,sp of 425 mΩ-cm2 and a BV of 2670 V was obtained for sin-gle-zone lateral IGBT with Ld of 80 μm. PN diodes and IGBTs with carrier lifetime enhancement exhibit a preliminary improvement in forward characteristics. For PN, a 5.5% voltage drop reduction was reached. For IGBT, a common base current gain of 0.3 was obtained. The influence of temperature, injection efficiency and lifetime on IGBT performance was investigated and summarized.