News Article
KLA Launches Candela 8620 Inspection System for HBLEDs
The tool is designed to enable improved substrate and MOCVD process control yield for high brightness LEDs.
KLA-Tencor Corporation, a supplier of process control and yield management solutions for the semiconductor and related industries, has introduced its new Candela 8620 substrate and epitaxy (epi) wafer inspection system.
Designed for high brightness light emitting diode (HBLED) manufacturers, the Candela 8620 provides automated defect inspection for LED materials such as gallium nitride, sapphire, and silicon carbide. This should enable enhanced quality control of both opaque and transparent substrates, faster time-to-root cause, and improved Metal Organic Chemical Vapor Deposition (MOCVD) reactor uptime and yield.
With its proprietary optical design and detection technology, the Candela 8620 detects and classifies sub-micron defects that are not consistently identified by current inspection methods, thereby enabling a production line monitor for these yield-limiting defects.
According to industry sources, as HBLED manufacturers transition production to larger wafer sizes and introduce new patterned sapphire substrate (PSS) processes, the economic impact of resulting process-induced defects is estimated at millions of dollars in lost product revenue per year, and MOCVD epi process issues may result in as much as 40 % of overall defect-induced yield loss.
"The enhanced performance of KLA-Tencor's Candela 8620 is an important part of our yield and cost reduction efforts," commented Iain Black, VP of manufacturing engineering and innovation at Philips Lumileds, an early adopter of the Candela 8620 system. "The system has been an important element in accelerating our process ramp as we transition to 150 mm substrates and is allowing us to select sapphire vendors with the highest quality."
Defects from substrate and epi processes impact device performance, yield and field reliability. The Candela 8620 can detect substrate defects such as micro-scratches and micro-cracks which can create epi process defects and directly impact LED yield and reliability.
It can also detect defect sources from lithography and etch processes for patterned sapphire such as missing bumps and resist voids, resulting in epi defects or reduced lumen output. Macro- and micro- defects in MOCVD processes, including hexagonal pits and bumps leading to electrical failure, and epi cracks which can adversely impact field reliability are also highlighted.
LED substrate and epitaxy layers pose significant inspection challenges due to high levels of background signal and nuisance defects. The Candela 8620's imaging and detection system is optimized to enhance the signal from relevant defects-of-interest while suppressing background noise. Aided by its multi-channel detection optics, the system additionally allows high purity classification of such defects, thereby allowing comprehensive statistical process control of critical MOCVD processes.
"KLA-Tencor is leveraging more than three decades of expertise in semiconductor process control to benefit customers in emerging markets like HBLED," said Jeff Donnelly, group VP of Growth and Emerging Markets at KLA-Tencor. "Recently, several HBLED manufacturers have installed the Candela 8620 system, and the system's proven ability to identify hard-to-detect defects allows customers to realize higher substrate quality and maximize return on MOCVD investment."
