Showa Denko to build 4-inch GaN LED fab
Showa Denko (SDK) has revealed plans to build a new GaN wafer fab at its existing site in Chiba, Japan.
The chemicals giant, which is already scaling up its production of AlGaInP LEDs (see related story), says that it has developed a new epiwafer fabrication process that is compatible with 4-inch sapphire substrates.
According to SDK, the new deposition method is a hybrid of conventional MOCVD and its proprietary "plasma-assisted physical deposition", or PPD. The company also says that X-ray analysis of nitride crystals grown on sapphire using the new process shows a significant improvement in quality when compared with those grown by MOCVD.
The Japanese firm adds that PPD not only allows 4-inch wafer production, but has also enabled it to develop the brightest blue LEDs on the market today.
"SDK will start commercial shipment of these blue LEDs within this year," said the firm. Thanks to the 4-inch upgrade, SDK is expecting to increase its blue LED production from the current level of 30 million units per month to 100 million units per month by the end of 2007.
The production scale-up is another part of SDK's self-titled "Passion" project, under which the Japanese company is expanding its high-brightness LED business aggressively.
SDK sees large LCD backlighting and general illumination as two key markets that it can penetrate with its latest generation of emitters.
GaN LEDs are typically manufactured on 2-inch sapphire wafers, although many believe that a scale-up to 4-inch production will be necessary before the technology can be produced cheaply enough to seriously penetrate the market for general illumination, such as lighting in homes and offices.
The US chip manufacturer Cree, which fabricates its LEDs on SiC substrates, recently revealed that it had qualified some of its processes for 4-inch wafer production (see related story).
However, scaling up sapphire-based production from 2-inch to 4-inch wafers has been a problem in the past, partly because of the increased warp of the larger material, and partly because local variations in temperature across the larger wafers created during the epitaxial process are more exaggerated (see related magazine features).
