Get Ready For A Mature HB LED Industry
Driven by rapid progress in technology, fast growth in display backlighting markets, and a potentially huge market for general lighting about to come, the high brightness LED sector is hurtling towards becoming a more mature volume manufacturing industry within the next few years. Though companies will of course maintain their unique core processes, the mature high volume manufacturing business will also require some changes, towards efficient supply chain management, towards more automation and towards more emphasis on tuning a controllable manufacturing process for consistent high yields. The industry is maturing very fast, much faster than the IC industry did, as it can learn from that experience," says Iain Black, Philips Lumileds VP of Worldwide Manufacturing Engineering & Innovation. “This is becoming a serious business. In the future we expect that with a smaller number of key players and a consolidating supply base, some of the custom variation will have to come out of industry. That will require standards, and they will need to be defined early enough to avoid delaying the development of the market, perhaps not in 2011, but certainly sooner rather than later." So some industry leaders are gathering to start to discuss these issues, at the first meeting of the newly formed SEMI North American HB LED Standards Committee November 11 in San Jose, California. The group is led by Black; Bill Quinn, chief technologist for MOCVD at Veeco Instruments; and Chris Moore, CEO of Semilab USA. SEMI invites participation from all interested parties. Parallel activities are expected to follow with committees in Europe, Taiwan and Japan. Contact Paul Trio at SEMI San Jose (firstname.lastname@example.org) for details. There is no charge, but participants must register beforehand. “I see standards as somewhat inevitable," adds Black, noting that it won’t be realistic to keep using all bespoke materials. “So it’s important to be involved in the process to have some input. It’s time to get the conversation started around what might be possible." Common ground in consistent input materials One key area of common ground is the characterization of incoming materials. Consistent measurement of purity for chemicals and benchmarks for LED grade materials like indium, gallium and metal hydrides, which all differ a bit from supplier to supplier, could be a start, and might not be too difficult because there are a limited number of suppliers. Substrate standards are typically a first step, but with the radically different processes used by major makers, some argue that even agreeing on a common thickness for 150mm sapphire wafers will be difficult. But others counter that one thinner ~1mm standard for those who thin the wafer down and prefer a thinner substrate, and another thicker ~ 1.3mm standard for those who remove the epi layer and prefer a thicker substrate, could probably handle most production needs, while doing away with much of the individual customization, enabling efficient supply chain management. Consistent measuring methods will help get more die in high value bins Another key area for potential gain from consensus on best practice is metrology and test. As the HB LED sector matures, and moves from the realm of the development engineer to the manufacturing engineer, it will begin to move away from its current focus on volume, to focus more on control of the established manufacturing process, and begin to pay more attention to the operational benefits of yield, identifying and tracking yield issues as early in the process as possible. But the process is currently hindered by everyone measuring different things in different ways. To measure something as basic as wavelength uniformity on the wafer, for example, some LED makers use electroluminescence tests, others use photoluminescence tests, some measure peak wave length, and others measure dominant wavelength--and all of those give different results. “If everyone could agree on one of those measures as best practice, it would get everyone talking about the same issues," argues Veeco’s Quinn. Materials, substrates, automation and metrology are usually the first areas to standardize as an industry matures, says Semilab’s Chris Moore, noting the accelerating speed with which some other sectors have moved up to consistent volume manufacture. The solar industry, which also differentiates on process IP, was skeptical of manufacturing standards several years ago, but has now embraced standards with amazing rapidity. Now two years in to starting standards discussions, there are now some 400 photovoltaic industry experts working to facilitate efficient volume manufacture, starting with coming to a consensus on the best measurement methodology for purity and setting benchmarks to define PV grade materials, and agreeing on carrier and equipment interfaces to facilitate automation. Get ready for automation Though small wafers, cheap labor and long batch processes have limited the need for automation so far, the LED industry is transitioning to more and more automation as it goes to larger wafers and higher volumes. Robotic wafer handling, automated glove boxes, interbay automation, mini-environments and standardized carriers such as SMIFS are all technologies that will become pervasive in LED fabs of the future, argues Clint Haris, senior VP of the Systems Solution group at Brooks Automation. He points out that LED makers are starting to look towards automation to improve yields and traceability. “The industry is rapidly evolving from manual operation to fully automated factories," he says, noting that the LED industry has seen change in the last five years that took 40 years in the semiconductor industry. “Things are moving so quickly, standards need to focus on the leading edge, 6-inch wafers, 6-inch cassettes, and some sort of wafer or carrier-level identification for traceability as the basics to enable automation."