Sumitomo Metal Mining Co., Ltd. has set up a production line for large sapphire substrates at its fully-owned subsidiary Okuchi Electronics Co., Ltd., and has started mass production.

Sapphire substrates are used as a substrate for fabricating gallium nitride for use in white and blue LEDs. As the market for white LEDs expands from backlighting for large-size liquid crystal televisions to include general purpose lighting, demand from LED manufacturers for large sapphire substrates which offer an opportunity to improve productivity has also increased. Since the start of 2012, SMM has moved forward with the installation of new large crystal growth furnaces and an increase in the number of substrate processing lines at Okuchi Electronics. These operations are now complete and mass production of 6-inch-diameter large sapphire substrates has begun.

The production of 6-inch sapphire substrates necessitates technology for the growth of large crystals, and SMM has developed its own original techniques for growing large, single sapphire crystals based on the crystal growth technology it has developed over many years. SMM has established technologies that allow the rapid growth of large single sapphire crystals with a diameter of 30cm and a weight of 80kg, and has instituted a world-class mass production system for large substrates.

Furthermore, growth techniques for very large single sapphire crystals with a weight of 130kg that allow a further increase in productivity for large substrates have also been developed, with mass production due to start in FY2013.