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Fuji Electric Develops “SiC-MOSFET with trench gate structure,” offering some of the lowest resistance in the world
June 26,2017
Fuji Electric Co., Ltd.
Tokyo, June 26, 2017 - Fuji Electric Co., Ltd. (TSE:6504) (“FE”), headquartered in Tokyo, Japan, led by President Michihiro Kitazawa, is pleased to announce that it has developed the “SiC-MOSFET*1 power semiconductor with a trench gate structure.” This product is capable of delivering some of the lowest resistance in the world and therefore contributing to significant energy efficiency improvements when used in power electronic devices.
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*1
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Metal-Oxide-Semiconductor-Field-Effect-Transistor
1．Background
Fuji Electric is in the process of enhancing its development of competitive products that make full use of the company’s extensive expertise in power electronics technologies. One of the key devices in this process is the power semiconductor. We’re now expecting the use of next-generation power semiconductors made from silicon carbide (SiC) rather than silicone (Si) to become increasingly common and widespread, and are projecting that Fuji Electric’s SiC power semiconductor market will grow to nearly three times its current size (to around JPY 120 billion) by 2020.
Compared to silicon power semiconductors, SiC power semiconductors offer lower power loss (low loss), an advance that can contribute significantly to energy efficiency improvements in the power electronic devices in which they are installed. In October 2013, Fuji Electric was a global pioneer in setting up an SiC power semiconductor production line (for six-inch wafers) at its Matsumoto Plant, accelerating product development. At the same time, we have been pushing to create more in-house power electronic device applications in our inverters, uninterruptible power supply (UPS) devices, and more.
Just recently, we have developed the “SiC-MOSFET1 power semiconductor with a trench gate structure,” a product that is capable of delivering some of the lowest resistance in the world*2. We are also aiming to make our All-SiC modules*3 commercially available by the end of fiscal 2017, while also installing them on our own power electronic devices as we strive to make our products ever more competitive.
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*2
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Fuji Electric has been participating in “Tsukuba Power Electronics Constellations (TPEC)” since fiscal 2012, making use of outcomes from its joint research with the National Institute of Advanced Industrial Science and Technology (AIST)
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*3
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Configured with an SiC-MOSFET and SiC-SBD (Schottky Barrier Diode)
2．Development overview
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Power semiconductors are formed by installing a transistor on a wafer, and come in two structures: “a planar gate structure” or “a trench gate structure.” Compared to a planar gate structure, in which the current path is created on a horizontal plane, the trench gate structure digs trenches in the wafer to create a current path in the perpendicular direction, shortening the width of the cell (see figure below) and allowing for more cells to be installed on an element of the same size. This in turn makes it possible for more electrical current to flow through the semiconductor.
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The key to developing a trench gate structure is finding a way to lower the electric resistance of the crystal face (the surface along which current flows) at the “gate” that controls whether the current is flowing (ON or OFF). Fuji Electric has used its proprietary technology to achieve some of the lowest specific on-resistance in the world—3.5 m Ω cm2 at a threshold voltage of 5 volts—without sacrificing reliability. We’ve thus succeeded in lowering electrical resistance by more than 50% compared to a planar gate structure.
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If an All-SiC Module equipped with our recently developed SiC-MOSFET element with trench gate structure is installed on an inverter (with an output of 7.5 kW and a frequency of 20 kHz), it is possible to reduce power loss by 78% compared to the use of a silicone (seventh-generation IGBT module) product.
The All-SiC Module soon to be installed with the element
Recently-developed SiC-MOSFET element with trench gate structure
3．Key performance features