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Update(MM/DD/YYYY):01/08/2020

Development of SiC-based Next Generation Transistor Structures

– Significant reduction of on-resistance, which is an index of transistor efficiency –


Researcher: HARADA Shinsuke, Leader, SiC Device Process Team, Advanced Power Electronics Research Center

Points

  • Application of next generation structures to SiC-based transistors, and achievement of the world's lowest on-resistance
  • Demonstration that the developed transistors have superior performance, such as high temperature characteristics and dynamic characteristics that are important for practical use
  • Expected to contribute to downsizing and enhanced efficiency of power conversion systems and the creation of new power systems
Figure
The developed two types of SiC trench gate type super junction (SJ) MOSFET


Background

In order to promote the effective use of energy and realize a low-carbon society, it is necessary to dramatically increase efficiency, reduce size and weight, and enhance functions of power electronics equipment by advancing power electronics technology for power conversion (DC/AC conversion and voltage conversion) and control.

Silicon carbide (SiC) has physical properties that are advantageous for downsizing and enhancing the efficiency of power devices, so it is expected as a promising material for next generation power devices.


Summary

Through joint research with Fuji Electric Co., Ltd., Sumitomo Electric Industries, Ltd., Toyota Motor Corporation, Toshiba Corporation, and Mitsubishi Electric Corporation, the researcher has developed 1.2 kV withstand voltage class vertical super junction (SJ) MOSFETs that use semiconductor SiC and achieved the world's lowest on-resistance for a SiC transistor. The developed SJ-MOSFETs were also demonstrated to have superior high temperature characteristics and dynamic characteristics, which are important for practical use.

A SJ structure with alternating n-type and p-type pillars has been demonstrated to effectively reduce silicon (Si) transistor on-resistance. However, application to SiC transistors has not progressed due to the difficulty of fabricating SJ structures. The researcher applied AIST original SiC transistor fabrication technology to achieve well-controlled SJ structures with a narrow pitch. This made it possible to realize trench gate type MOSFETs with SJ structures that have a narrow pitch and low on-resistance, which significantly reduced the on-resistance of 1.2 kV withstand voltage class SiC-MOSFETs. The developed technology is expected to contribute to further downsizing and enhanced efficiency of electric vehicle power systems, to which SiC is expected to be applied, and the creation of new power systems.







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