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10 April 2007


GaN-on-glass process could yield 48% savings for LED epi, suggests cost of ownership model

BluGlass Ltd of Sydney, Australia (which was spun off from Macquarie University in mid-2005) has released figures suggesting that its remote plasma CVD (RPCVD) process for low-temperature deposition of GaN onto glass substrates (rather than conventional MOCVD on sapphire) can cut the cost of manufacturing GaN-based LEDs at both the epiwafer level and the assembled device level, according to an independent assessment commissioned from US-based firm Wright, Williams & Kelly Inc (WWK), a cost -of-ownership modeling group for the semiconductor industry.

The model compares the RPCVD process on 2-inch diameter buffered glass substrates versus the more conventional MOCVD process on similar-sized sapphire substrates, based on a 21 x 2”-wafer-capacity commercial production tool. MOCVD data was collected by an independent industry expert and includes current best estimates of material and other input costs and productivity for a US-based manufacturing facility.

Wafer-level analysis shows a cost saving of 48% for RPCVD, driven by a 70% reduction in materials and consumables costs (mainly due to using glass rather than sapphire substrate and replacing costly and toxic ammonia with nitrogen). In addition, over a projected useful reactor life of seven years, operating costs are almost $8m lower due to RPCVD’s operating temperature of 700°C being about 300°C lower than that of MOCVD.

Also (using an outside expert to provide a backend assembly process flow) an integrated downstream assembly cost model for a 0.35mm x 0.35mm square mesa-structured chip in a standard ‘Blue LED T1’ encapsulated package with a water-clear lens shows that the RPCVD process leads to a 10% cost advantage at the final assembly level for a simple blue LED device (assuming no difference in post-epiwafer processing costs between MOCVD-grown GaN-on-sapphire and RPCVD-grown GaN-on-glass).

The details have just been presented to several international LED equipment, materials, wafer and device manufacturers during a world tour by CEO David Jordan. “The reception to our BluGlass technology was very encouraging,” says Jordan. “They additionally valued our demonstrated ability to uniformly deposit GaN over large area and the prospect of tight process control,” he adds (BluGlass recently demonstrated good-uniformity nitride deposition over a 6-inch diameter wafer, and last November demonstrated highly uniform nitride deposition on 4-inch glass wafers).

“This is a very significant breakthrough for BluGlass in proving the potential of our technology to cut the cost of LED manufacture,” Jordan says. With millions of wafers and tens of billions of packaged LEDs produced each year, such cost savings translate to significant potential gains to LED makers. Current LED manufacturing costs have restricted their use to electronics, mobile handsets and special situations such as traffic lights and signage. The high cost of making LEDs has to date been one of the key factors in limiting their uptake in the general lighting market for homes, businesses and industry . The development of cheaper and more environmentally friendly LEDs should accelerate their penetration into the $100bn per annum market for general lighting products, reckons BluGlass. The market for high-brightness LEDs alone is valued at $4bn per annum and is expected to rise to more than $7bn per annum by 2009, according to market research firm Strategies Unlimited.

BluGlass will continue its progress in demonstrating device and process performance and developing a professionally engineered manufacturing tool, Jordan says. “In the coming months our new facility in Silverwater in Sydney will showcase the technology, the fabrication process and our commercial production demonstration equipment.”

See related item:

BluGlass touts 6-inch GaN-on-glass technology developments