KLA-Tencor has announced that Epistar, a leading Taiwanese manufacturer of LED chips, has adopted its Candela substrate and epwafer inspection system.

KLA says this order marks the growing adoption by LED device manufacturers worldwide of this advanced inspection system for wafer defect detection and classification at production-grade throughputs.

The introduction of the Candela tool to Epistar's manufacturing process provides automated inspection methods for sapphire substrates to ensure vendor quality, and provides greater visibility into the GaN epi process to help detect the root causes of defects and early prediction of process excursions.

According to an Epistar spokesperson, "Adoption of KLA-Tencor's Candela inspection has provided Epistar with improved sapphire quality control and MOCVD process control."

Substrate defects are known to impact epi process yield, and the Candela system provides increased sensitivity to these yield-limiting defects. With its proprietary optical design and detection technology, the Candela system detects and classifies sub-micron defects - including micro-cracks and -scratches, polishing and brushing streaks, and chemical residues.

As LED manufacturers transition production to larger wafer sizes and introduce new patterned sapphire substrate (PSS) processes, the economic impact of resulting process-induced defects is significant. For defects occurring during the epi process steps, the Candela tool can detect hexagonal pits and bumps which can lead to electrical failure and epi cracks that can adversely impact field reliability.

"The Candela system allows LED manufacturers to conduct root cause analysis to speed process development, quickly fine tune production processes to minimise process excursions, and ultimately achieve higher yield per wafer," said Jeff Donnelly, group vice president, Growth and Emerging Markets (GEM) Group at KLA-Tencor. "We are pleased to add Epistar to the growing list of Candela adopters."