RESURF n-LDMOS Transistor for Advanced Integrated Circuits in 4H-SiC

The electrical behavior of lateral 4H-SiC n-laterally-diffused metal-oxide semiconductor (LDMOS) transistors with reduced surface field (RESURF) for integrated circuits was designed, measured, and modeled using different design variations. An additional implanted n-layer forming the drift region of the device in a p-doped epitaxy promotes a RESURF and thereby enhances the breakdown capability. The design rules of the presented power MOSFET are compatible to an existing technology for a novel 20-V 4H-SiC CMOS process. The dose of the additionally implanted RESURF region with a depth of approximately 390 nm was 3.5⋅1012 cm −2 . Breakdown voltages in the range of 372-981 V and ON-state resistances from 1000 down to 54 mO cm 2 were measured, depending on the design variations. The best measured figure-of-merit (FOM, V2BD/RON ) value results in 12.3 MW/cm 2 . Additionally, the electrical behavior of the presented n-LDMOS transistor was compared to a TCAD simulation model. Hereby, design guidelines concerning the length of the channel, drift region, and field plate were derived, which will be helpful for further investigations. Moreover, according to the simulations, a deeper RESURF region of 1 mm and a higher RESURF dose of 6⋅1012 cm −2 would even result in FOM values above 43 MW/cm 2.