More efficient and reliable SiC devices for a greener future
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Researchers at The University of Osaka have developed a novel technique to enhance the performance and reliability of silicon carbide (SiC) metal-oxide-semiconductor (MOS) devices, a key component in power electronics.This breakthrough utilizes a unique two-step annealing process involving diluted hydrogen, to eliminate unnecessary impurities and significantlyimprove device reliability.
A conceptual diagram of diluted hydrogen annealing of SiO2/SiC structure. The background scenery is inside the Class 1 cleanroom located in Graduate School of Engineering, The University of Osaka.
The University of Osaka
SiC power devices offer superior energy efficiency compared to traditional silicon-based devices, making them ideal for applications like electricvehicles and renewable energy systems. However, previous attempts to improve SiC MOS device performance relied on introducing impurities like nitrogen,which unfortunately compromised reliability and limited operating voltage range. This necessitated strict gate drive design, hindering wider adoption.
The University of Osaka team discovered that a two-step high-temperature hydrogen annealing process, performed before and after gate oxide deposition,could drastically improve both performance and reliability without the need for these problematic impurities. This process effectively removes defects at the oxide/SiC interface, resulting in a lower interface state density andhigher channel mobility. The devices demonstrated improved immunity againstboth positive and negative bias stress, expanding their operational voltagerange.
This breakthrough has significant implications for the future of powerelectronics. By enhancing the reliability and performance of SiC MOS devices, this technique paves the way for their wider adoption and contributes towards a more energy-efficient future. This will be particularly beneficial inapplications requiring high power and switching frequencies, such as electric vehicle inverters and renewable energy converters.
"SiC MOS devices, despite being in mass production, haven't yet reached their full potential in terms of performance and reliability," explains Prof. TakumaKobayashi, the lead researcher. "Our findings offer a solution to this long-standing challenge and open up exciting new possibilities for SiC power devices. We overcame many hurdles during this research, and I'm grateful to all my co-authors for their contributions."
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