“Air Water built up a plant to produce SiC substrate for power devices (SiC on Si substrate) of its own technology in Nagano Prefecture in April of this year, and is now shipping samples to the domestic device manufacturers.

As already reported, the substrate is used to produce gallium nitride (GaN) targeting at high-frequency devices for mobile communication instruments like a cell phone. It is most characteristic to have formed a thin film of silicon carbide (SiC) on the existing silicon substrate to enable easy formation of GaN film. They say that the substrate enables to produce the GaN substrate which costs lower than SiC bulk substrates.

The device using GaN of compound semiconductor is said to have better frequency responses than the existing Si device. The use of GaN device can make usable the high frequency communication range which is out of use at present. This feature is said to enhance a higher function of the mobile communication like a smartpnone and expand a new demand. Furthermore, in case that the GaN is used for a power supply of personal computer, household power outlet or automobile power device, we can expect realization of down-sizing, high temperature performance and higher speed which has been deemed to be impossible with the current Si device.

For one thing, however, a GaN device substrate is more expensive and not so easy to have any larger diameter comparing with Si. For commercialization, therefore, it has been indispensable to realize cost reduction and mass production.

Air Water has made it possible to supply an inexpensive GaN substrate with a large diameter (8 inch) by forming a thin SiC film on the existing Si substrate which is well compatible with GaN.

In order to develop the substrate, Air Water applied and attained to use practically the technology which has been fostered by atmospheric-pressure plasma and NV nitriding which is based on its own VCE (high-vacuum epitaxial) equipment. The new plant is capable to produce SiC on Si substrates from 2 to 8 inch, and also with GaN film (2 to 6 inch) formed on thin SiC film. The production capacity is 2000 sheets per month at maximum at 8 inch.

Ichiro Hide of SiC Business Division says,”As the GaN device market is expected to grow up to a level of 88 billion in 2020, we would like to tackle the needs for replacements from the current Si devices and new demands for distinctive GaN particularly. We first try to respond to user needs by delivering samples.” Although the compound power devices (SiC or GaN) to replace the existing Si devices are surely highly functional and energy-saving device materials, their production cost becomes higher than Si. Therefore, it would be a subject for commercialization whether the increased cost can be made up for by added values from users.

Hide added, “We can attain cost reduction as a whole system by changing into SiC or GaN which needs less or no refrigeration. It will also be necessary to propose a new business model so that such merits may be reflected on the cost for devices.””