By Debra Vogler, senior technical editor
February 17, 2011 -- Veeco Instruments' new TurboDisc MaxBright GaN MOCVD multi-reactor system is poised to take advantage of what the company believes is an accelerated rate of LED TV penetration (Fig. 1). According to Jim Jenson, VP of marketing at Veeco, who cited DisplaySearch/Veeco estimates in a podcast interview with SST, LED TV penetration is expected to reach 50% in 2011 and increase to ~80% in 2013, or perhaps sooner. Among the reasons LEDs are replacing LCD TVs that are backlit with CCFL technology are:
- LEDs enable much thinner TVs and lower power consumption,
- LEDs have better display characteristics (e.g., LEDs can do local dimming in direct-lit displays),
- LEDs do not contain mercury, as do CCFLs.
Besides LED TVs, Jenson says many LED manufacturers are already positioning themselves to take advantage of the move to replace incandescent light bulbs and fluorescent tube lighting.
|Figure 1. LED TV opportunity. SOURCES: DisplaySearch Q4/10 and Veeco estimates.|
The new system targets manufacturing of high-brightness LEDs (HBLEDs) and is capable of single- or multi-chamber layer growth; this allows for LEDs to be manufactured either serially (individual layers of LEDs can be grown sequentially in each reactor) or in parallel (the entire LED is grown on a per reactor basis). Two to four different reactors can be mounted around a central handler, which can handle a higher capacity carrier, and according to Jenson, each reactor can handle 20% more wafers than the previous generation.
|Figure 2. a) Within-wafer uniformity and b) Wafer-to-wafer uniformity.|
An enabling feature of the tool is model-based temperature control, which uses a proprietary close-loop thermal control algorithm. Jenson explains that conventional closed-loop thermal control uses PID technology, which has a relatively slow settling time, taking a number of minutes for the temperature to stabilize after significant excursions. The new tool uses an algorithm that creates a 3D model in time of the entire thermal environment of the reactor; it requires about 500 differential equations being solved simultaneously every time there is a temperature change. "This results in very fast transitions, and very fast settling time between one temperature change and another," said Jenson. "We see a 5-10% throughout improvement."
According to Jenson, the tool has a >90% yield in a 5nm bin which means 90% of the LEDs on a platter, or 90% of the LEDs within a wafer, are within a wavelength range of 5nm (Fig. 2).