Technology:
A research team led
by Shinichi Shikada of the Diamond Research Laboratory of Advanced Industrial Scienceand Technology built a substrate made of artificial diamond. It is 4 cm deep, 2
cm wide, and 0.5 mm thick. The research team enlarged the area of microscopic crystals
using methane gas. It plans to build a disc-shaped substrate 5 cm in diameter
toward next March. Because it will be put on the production line of LSIs, it
will allow for continuous production of power semiconductors. The diamond
substrate can resist more than 30 times higher voltage than the silicon
substrate and about four times higher voltage than the silicon carbide
substrate. In addition, the diamond substrate can reduce the power loss in
operation by up to one tenth.
Silicon carbide and
gallium nitride are expected to replace silicon as the material of substrate. Mitsubishi Electric is testing subway cars that incorporate silicone carbide power
semiconductors in Tokyo, and it successfully reduced the power loss of the
inverter by 30%. Because diamond has a higher ability to resist high voltage,
it is expected to contribute to energy saving. In addition, should it be used
for the power conversion equipment of an electric vehicle, the cooling system
will be downsized to make an electric vehicle smaller.
It was generally
believed that the practical application of a diamond power semiconductor will
be after 2025, but the technology to have built a larger than 5 cm disc-shaped
substrate will accelerate the development. A research firm predicts that the
world power semiconductor market will increase from 1,860 billion yen in 2011
to about 3,000 billion yen in 2020. Some estimate that replacing silicone by
silicon carbide as the material of all power semiconductors will save power
equivalent to 8 nuclear power plants with one million kW each in 2020. Diamond
and gallium nitride will save power greater than silicon carbide.
A silicon carbide
substrate developed by Denso
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