Originally Structured High-Efficiency and High-Stability SiC Power Transistor
June 29, 2015
Sumitomo Electric Industries, Ltd.
*This press release was issued on June 4, 2015 in Japan.
Sumitomo Electric has developed a power transistor of an original structure consisting of silicon carbide (SiC) which is seen as a next-generation power semiconductor. The new transistor achieves low on-state resistance, high stability and other excellent performance characteristics that are required for electric vehicles (EV)/hybrid electric vehicles (HEV), solar power conditioners and other applications.
With recent growing need for energy saving, reducing power conversion loss is strongly required of power semiconductors. Compared with silicon (Si) that is used widely for power devices, SiC has higher blocking voltage and lower on-state resistance. Since these features enable dramatic reduction of the power loss of electric power apparatuses, SiC is seen as a next-generation power semiconductor. On the other hand, SiC is a compound semiconductor and its crystal defect poses a reliability-related problem.
The new SiC transistor is a V-groove metal oxide semiconductor field effect transistor (VMOSFET, Figure 1) that uses a particular plane orientation (0-33-8) for the channel that turns on/off the flow of electrons, enabling the formation of an oxide film interface with relatively low defects compared to a normal orientation (0001). As a result, the new transistor can achieve a blocking voltage of 1,200 V and a remarkably low on-state resistance of 2.0 mΩcm2. The low-defect performance of this transistor also significantly stabilizes the threshold voltage fluctuation (at 0.12 V or less at 175℃ for 1,000 h) that has prevented the practical use of SiC transistors.
Due to these advantages, the new SiC transistor is suitable for use in automotive electronic devices whose demand is expected to increase in future with computerization of EV/HEV and other vehicle drive systems. For photovoltaic and other regenerative energy generation system applications, the new transistor was installed in the solar power conditioner that is being developed by Sumitomo Electric's Power System R&D Center and has demonstrated the highest level of efficiency (97.6%) in the industry (Figure 2).
Sumitomo Electric prototyped the new transistor chip of 3 mm square, by epitaxial growth* on a 6-inch substrate. The company will use the preproduction line of the Tsukuba Power Electronics Constellations (TPEC) operated by the National Institute of Advanced Industrial Science and Technology to establish a mass-production technology for a new business.
A researcher of Sumitomo Electric reported these achievements at the 27th International Symposium on Power Semiconductor Devices & ICs (ISPSD), and he won the Charitat Award.