eS 35 E-Beam

The KLA eS 35 is an e-beam inspection system manufactured by KLA. The system is classified under metrology and inspection equipment used in semiconductor manufacturing.^[1][2]

An e-beam inspection system generates a narrow beam of electrons from an electron source, typically a field-emission gun. The beam is focused and scanned over the wafer surface under high vacuum. Interactions between the primary electrons and the wafer material produce secondary electrons and backscattered electrons. Detectors collect these signals to form high-resolution images of the surface, revealing defects such as particles, pattern faults, and electrical anomalies.

In a semiconductor fabrication facility, e-beam inspection tools are typically deployed after optical inspection steps. Optical tools provide high-throughput defect detection across the full wafer, while e-beam tools are used for high-resolution review of suspected defect locations identified by optical scans. The e-beam system can also be used for direct inspection of critical layers where optical methods are inadequate.

E-beam inspection is commonly applied to advanced logic and memory devices at technology nodes below the resolution limit of brightfield or darkfield optical systems. The tool may be integrated into the defect monitoring loop for process development, yield ramp, and production monitoring.

Applications include process window qualification, reticle qualification, and monitoring of critical layers such as gate, contact, and metal interconnects. The high resolution of e-beam inspection makes it essential for technology nodes where defect sizes fall below the practical resolution of optical inspection.