Candela 8720

The KLA Candela 8720 is an advanced surface inspection system designed for compound semiconductor wafers. The system is used primarily in the LED, photonics, and communications markets. The Candela 8720 captures a variety of mission-critical substrate and epitaxial defects. The system supports wafer sizes of 4, 5, 6, and 8 inches.^[2][1][3]

The Candela 8720 employs proprietary optical technology to simultaneously measure scatter intensity at varying degrees of incidence, topographic variations, surface reflectivity, phase shift, and photoluminescence. The system uses red laser and violet laser illumination for its multiple detection channels. The tool can be operated in three modes: high-throughput, standard resolution, and high resolution. In high-throughput mode, the Candela 8720 functions as a simple particle counter. In the advanced classification mode, multiple detection channels enable accurate detection and classification of various defect types. The inspection method achieves full-surface coverage in minutes, producing high-resolution images and wafer maps with automatically classified defects.^[1][3]

The Candela 8720 is used after metal-organic chemical vapor deposition (MOCVD) epitaxial growth processes. The system enables automated wafer inspection with statistical process control (SPC) methodology. The tool helps minimize MOCVD reactor process excursions and increases MOCVD reactor uptime. Implementation of the Candela 8720 can significantly cut yield loss due to epi defects.^[1][3]

The Candela 8720 is intended for the LED, photonics, communications, and other compound semiconductor markets. The system is sensitive to common yield-impacting defects including micro-pits, cracks, hexagonal bumps, showerhead droplets, crescents, scratches, and other topographic defects. The system can detect and classify both macro and micro defects on compound semiconductor substrates such as silicon, sapphire, patterned sapphire (PSS), silicon carbide (SiC), and gallium nitride (GaN). The Candela 8720 is suitable for both process development and high-volume manufacturing process control.^[1][3]