Two-step annealing process boosts silicon carbide device efficiency and reliability

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 significantly improve device reliability.

The work has been published in Applied Physics Express.

SiC power devices offer superior energy efficiency compared to traditional silicon-based devices, making them ideal for applications like electric vehicles 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 and higher channel mobility. The devices demonstrated improved immunity against both positive and negative bias stress, expanding their operational voltage range.

This breakthrough has significant implications for the future of power electronics. 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 in applications 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. Takuma Kobayashi, 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.”