LEDs are fundamentally semiconductors, running up against fab and packaging issues, says Philips Lumileds

Meredith Courtemanche, digital media editor

May 18, 2011 — Iain Black, VP WW Manufacturing Engineering, Technology & Innovation, Philips Lumileds, presented "LED Market & Technology" in The ConFab’s final session, which focused on emerging semiconductor technologies.

LEDs are fundamentally semiconductors, Black notes. Just like semiconductors, the die is integrated into a package (which is designed to increase illumination), then assembled into an array, and eventually an end device.

LED manufacturing starts with indium gallium nitride (InGaN) epitaxy growth on a sapphire wafer (2" to 6"). The epi step is accomplished using metal organic chemical vapor deposition (MOCVD). The LED industry is highly interested in using silicon in the future as a substrate. Wafer processing (lithography, etc.) forms the LED, then phosphor is applied at the packaging stage. LEDs are tested, much like semiconductors, before array assembly. Phosphors create LED light colors.

Like in chips, different device architectures are used to form LEDs. Black described vertical thin film devices, which are lower cost but with limited options; lateral die; and thin film flip chips on ceramic substrates, which are AC compatible.

Unlike chip manufacturing, the supplier base is fairly small, Black said, with 2 dominant suppliers for MOCVD tools, for example. And processes lack the level of automation seen in the semi chip fab industry. Wafer size transitions are occuring rapidly, and thicknesses also vary. The forefront of LED fab, much like chip fab, is wafer level packaging (WLP), cluster tools for automation, and advanced substrate materials. Black said "LED devices may just be the ultimate analog compound semiconductor products," if issues such as clear device technology path, performance and cost metrics are met. Standards will go a long way toward this.

The argument for LED bulbs over traditional incandescents is fairly clear from a performance standpoint: 50% efficiency over 5%, 25x longer life, 12W energy consumption to 60W bulb. The initial cost is prohibitive, $40 compared to about 50 cents, but cost over 25,000 hours remains $40, while incandescents will ring up to $165.

Consumer/commercial lighting isn’t the only available market, with camera flash, electronics displays (TVs), and automotive lighting showing sizeable market opportunities. LED market penetration (versus traditional light sources) is accelerating, says Black, with significant upside in outdoor illumination through 2015, steady growth in automotive, and ramping usage for displays and flash. LEDs are a large, and growing, market. Not surprisingly, Taiwan, China, Japan, and Korea dominate LED production by capacity. Vertical integration of LED & Lighting businesses may be a critical success factor here (Philips, Osram, Samsung, LGI, Sharp).

See a summary of Black’s Session 5 co-presenter, David Icke, MC10 Inc., on flexible silicon nano-ribbons here. 

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