LED manufacturing highlights from Strategies in Light Day 2

February 9, 2012 — Day 2 of the 2012 Strategies in Light conference, and the first day of technical sessions, began with an adrenaline rush. The challenge posed to the audience was to identify the first ever Super Bowl TV commercial to feature a light emitting diode (LED) light. The first respondent would win $100, and it took only a few mental CPU cycles for someone to correctly shout out “Audi.” The conference has over 4,000 advance registrations, with a total of 5,000 attendees expected for conferences and to view the record 170 exhibitors.

Read Fury’s report from Day 1: Strategies in Light: Day 1, LED Lighting Report, New Start-ups

and from Day 3: Lithography, direct-attach LED architectures, packaging trends

The session was opened by Ella Shum, LED practice director at Strategies Unlimited. One prognosis is that China will soon be taking over the global sign market; it commanded 87% of the W/W market in 2011. Many smart phones are going to OLED displays. It was suggested that the iPhone will not go OLED until someone other than Samsung commands the majority of OLED manufacturing capacity. Even though the LED lighting market is growing at a 20% CAGR to 2016, the LED chip market is flat (CAGR -0.2%) because of price pressure even as unit growth is strongly positive.

Ling Wu, Secretary General of the Chinese Solid State Lighting Alliance, provided an overview of their strategy as captured in the next Five Year Plan. Energy savings is the dominant driver, with a target of 100B kWh saved. The 20M rural families still without electricity are driving a market for off-grid LED lighting.

Eric Kim of Soraa, Inc. took a holistic approach to LED lighting for space illumination. Readers are referred to an article in today’s (Feb 08, 2012) Wall Street Journal on the company. Unlike most LEDs that use blue emission to pump phosphors for their range of colors, the Soraa products use violet light to pump a different set of phosphors, giving characteristics distinct from others in the market.

Editor of LEDs Magazine Tim Whitaker provided his observations on the European LED lighting industry. General lighting LED market share is just shy of 10% in 2011, in spite of being two years into a mandated conversion roadmap away from incandescents. This transition is expected to inject €20B into the European economy.

Ned Tozun of d.light Design is turning to LED solutions for off-grid household lighting in third world rural areas. There is still a surprisingly large population that has no access to electricity, or unreliable limited access. The primary means for night lighting are kerosene lanterns and electric bulbs powered by lead acid batteries that must be carried to a local diesel generator  for daily recharging. In India, the government subsidy to keep kerosene prices affordable is ~$6B, approximately the same as the national budget for education. The sociological benefits from relatively low-tech implementations of solar chargers and LED lighting at night extend to increased study time and improved health for children due to the elimination of kerosene (which is typically several grades below what is available in the US in terms of adulterated effluents).

Figure 1. Population without electricity.

Overheard mid-morning: “I’m surrounded by a bunch of technical propeller-heads talking about LED chip manufacturing and I’m not sure I can keep up.” Funny, I felt like I was surrounded by marketeers who were excited about upside market potential but had no idea what the inside of a fab looks like, at least through the morning plenary session. Fortunately, I was able to take refuge all afternoon in the LED Manufacturing track, where my propeller spun freely.

Seth Coe-Sullivan of QD Vision opened the session on phosphors with his overview of the only company focused on quantum dots exclusively for the lighting industry. Their quantum dots can operate in both photoluminescent and electroluminescent (for QLEDs) modes. The underlying physics is said to provide greater efficiency and spectral purity than phosphor technology.

Iain Black of Philips Lumileds Lighting talked about the challenges of LED manufacturing from the perspective of rapidly delivering products to market that are responsive to rather fast changes in consumer mood. One important element is to move the product customization point as late in the production process as possible, allowing many products to draw from a common substock. Lumileds manufactures on 150mm wafers; most LED fabs still run smaller wafers.

Karen Savala, President of SEMI Americas gave the supplier-side perspective on consolidation, expansion and long-term planning for LED manufacturing. Global manufacturing is normalized to 4” wafer equivalents; capacity is expected to reach 2M wafers/month this year. Sapphire LED substrates are expected to reach 50% 6” wafers in 2014, and this wafer size is where the SEMI Standards activity is focused for LED.

Figure 2. LED dedicated fabs, 10-year span. SOURCE: SEMI Opto/LED Fab Forecast, November 2011.

Jacob Tam, President of TSMC Solid State Lighting Ltd., explored the question of whether a large semiconductor manufacturer can accelerate LED cost reduction. He started with a very nice spider chart comparing the state of manufacturing in the two technologies. Various manufacturing and design tools were compared between the two, but in the end he remained quite silent on the details of what TSMC had in mind for its own LED manufacturing future. One expectation is that binning control will be much tighter when leveraging TSMC’s process control experience.

Figure 3. The fundamental differences between semiconductors and LEDs.

James Broderick of US DOE talked about the government-industry roadmap for improving solid-state lighting manufacturing in the US. The underlying motivator is the creation of sustainable US manufacturing jobs. The metrics call for OEM lamps priced at $5 by 2020, compared to $23 today. There are ~$45M in projects funded today, with a planned pathway to $114M. A funded KLA inspection tool tested at Philips Lumileds reduced production costs by 10%.

Figure 4. DOE funding by program pathway.

Raja Parvez, CEO of Rubicon Technology spoke about the move to larger diameter sapphire wafers. Solid state lighting is the largest consumer of their products, followed by silicon on sapphire and optical windows (aerospace). Rubicon expects 6” wafer share to be 70% by 2020, with a subsequent trend to 8”, following the semiconductor trend.

Figure 5. Sapphire wafer diameter trends. SOURCE: Yole Developpement.
LED chip manufacturers transitioning to larger-diameter substrates to reduce cost
 –Several chip manufacturers announced plans to move into volume production on 6" substrates in 2011
 –We have been supplying R&D volumes of 8" epi-polished wafers and are ready for high-volume production.

Abdul Lateef of Plasma-Therm talked about the advancements of front end PECVD deposition in adapting to LED manufacturing. Real time process control using optical emission interferometry is one of the innovations contributing to higher production repeatability and yield, with a control resolution of 50nm.

Michael A. Fury, Ph.D., is director & senior technology analyst, Techcet Group in North Plains, OR.

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