market analysis SiC devices & materials
The burgeoning SiC market
By the end of this decade SiC device sales will be netting a billion dollars and substrate revenues will be worth $350 million, according to market analyst Philippe Roussel from Yole Développement. He talks to Richard Stevenson about the chipmakers set to make the biggest splash and the type of substrate that they will be using.
Q a
After many years of waiting, some SiC chipmakers are now making transistors. Who is leading the charge?
Cree is definitely number one in terms of the
MOSFET. They are the first company to have developed and commercialised the SiC MOSFET, launching a 1.2 kV, 20 Amp device that will deliver 17 Amps at 100 °C. It’s a discrete design that was also developed for a US company Powerex. They made a field-effect module with a SiC MOSFET, which has the discrete as a die, not as a packaged chip.
Who else? If we stay with the MOSFET, the most advanced technology besides Cree is probably that of Mitsubishi Electric. It is making this device for internal purposes only, probably for motor control or inverters for AC systems.
Fuji Electric is developing MOSFET devices and involved in a product with AIST in Japan. It is supposed to open a SiC line that will be an open fab. Fuji’s is an interesting MOSFET technology, but it’s not fully developed yet. Northrop Grumman was developing a SiC MOSFET too. The company is very defence orientated and issues very little information. And Rohm and Toshiba are also active in this area.
Q a
What about other types of SiC transistor?
SemiSouth introduced the SiC JFET in the market place three year’s ago in very limited quantities. They were the first company with normally-on and normally-off JFETs. One of the key advantages of these transistors is that they are much easier to manufacture – and probably less expensive as well – because there is no oxide and the geometry is simpler. Yields depend on the micropipe density. So they depend on what type of substrate you start with, and how big your device is. With a MOSFET, die are quite big, so the chances of being on top of a micropipe can be huge. To increase the yield, you have to start with zero micropipe wafers that are much more
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www.compoundsemiconductor.net June 2011
Q a
Q a
That is a big advantage. So why are some manufacturers pursuing the MOFSET?
The MOSFET is a discrete device, offering chip-to-
chip replacement with an IGBT or silicon MOSFET. The JFET has to be driven a bit differently. But if you can operate it in normally-off mode, the industry is not reluctant to use it.
Does SemiSouth face competition in the JFET market?
Infineon is trying to enter this business. One of the key added values of its JFET is that they are pushing to it higher current densities to reduce the die size and the cost. Today, 50 percent of the cost is related to the substrate and epi, so if you can save space and size, you can save a lot of cost. As far as we understand, Infineon is looking at normally-on JFETs cascode-mounted, using silicon transistors to turn a normally-on JFET into a normally-off JFET. For high temperature applications, using silicon is probably an issue. Northrop Grumman is also involved in JFET development.
Q a
In addition to the MOSFET and the JFET, some other types of device are under commercial development, aren’t they?
Yes, there is the BJT transistor. Leading its development is TranSiC, the Swedish company; and Shindengen, a Japanese company. Shindengen is an advanced silicon-Schottky-diode developer, so it’s a key competitor of ST Microelectronics. It is really active in SiC, even if it is not that visible. The BJT is not in production yet. Cree is also doing some IGBT
expensive. You have some of these problems with JFETs, but the current density is much higher. So for the same current range you have much smaller die and less risk of being affected by micropipes.
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