High-Speed Reticle Qualification System

Wafer steppers play an important role in VLSI production. However, wafer exposure by a stepper requires both a perfect or defect-free reticle and an elaborate resist process. When a reticle is produced by mask shop its perfection or pattern integrity is guarantteed with a reticle inspection system. When introduced and used in the VLSI production, however, the reticle sometimes becomes defective due to falling particles and/or chrominum peel-off caused by inadequate reticle cleaning. Even with a pellicle, the reticle gets contaminated with dusts caused by careless handling. Therefore, the in-situ reticle inspection or reticle qualification is necessary to secure the exposure of product wafers.