Description
Silicon carbide (SiC) has been at the heart of the commercial power semiconductor industry for over two decades, owing to its larger breakdown electric field and superior thermal conductivity compared to silicon. In that time, there has been significant research and development into optimizing these devices. The main SiC rectifier is the SiC Schottky diode, which is formed simply using an interface between a metal and n-type SiC. However, concerns about the reverse bias leakage and the surge current capability led to the development of the Junction Barrier Schottky (JBS) and the merged PiN Schottky (MPS) architectures, which incorporate ion-implanted p-type regions inside the active area under the metal. The addition of ion-implantation complicates the fabrication and necessitates costly additional processing; furthermore, these devices, which now have regimes of bipolar operation, can suffer from “bipolar degradation”, which is a significant reliability issue in SiC. Given more recent developments in SiC device physics and engineering, we must ask: Are these implants still needed? We present here results of SiC Schottky diodes fabricated without any implantation processes. The homogeneous metal-semiconductor interface is formed on a plasma etched surface and exhibits nearly theoretical current-voltage characteristics in both conduction directions and over a wide temperature range. We implement an edge termination using an epitaxial p-type ring with a carefully designed angled etch profile, rather than an implant process, which is effective and enables us to reach reverse bias voltages up to 10 kV without destructive breakdown. Together, these allow us to design devices with comparable and even improved forward and reverse current characteristics compared to commercial JBS and MPS devices. Additionally, we demonstrate superior surge current capability than commercial MPS diodes. Our results highlight that the issues introduced by ion-implantation are not required to produce high performance SiC rectifiers.
| I am the presenting author | Yes |
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