In this paper we describe the early stages of introduction of the inspection and metrology capabilities for the large area
mask repair tools. Commercially available MRT platform was used as a basis for integration of defect repair, metrology,
review, inspection, and verification functions into a single MiRT prototype system. This system was designed for large
area LCD/PDP photomasks of Generation 7 and beyond. Advanced DUV femtosecond laser technology was developed
for repair of both clear and opaque defects on Chrome-on-Glass masks using laser CVD and laser ablation. Specifics of
the system design and architecture is discussed. Laser processing module was based on the projection optics with imaged
aperture. Image formation in such optical system is reviewed and outcome of the computer simulation is compared with
the experimental data. For the first time, we report results of the feasibility study of grayscale photomask repair using
laser CVD technology. By carefully controlling process parameters, we were able to deposit films with different
thickness and therefore variable transmittance. We also discuss die-to-database inspection of half-tone masks and
capabilities of the integrated metrology and review of the repaired photomask sites. Proprietary die-to-database
inspection and verification algorithms combined with distributed super-fast computer architecture allowed effective
process control with accurate, repeatable, and timely measurements. Different subsystems that enable integration of
repair, metrology, and inspection functions into the MiRT system are discussed.
In this paper we report for the first time on the development and performance of commercially available large area
photomask repair tools of the MRT series. MRT+1500 / MRT+2000 are advanced laser-based tools specifically designed
to repair high quality FPD (LCD & PDP) binary photomasks of Generations 6, 7, and beyond. MRT+2000 is the world's
first commercial tool capable of handling and repairing Gen 7 photomasks with sizes up to two meters. Another unique
feature of these tools is that they use a single DUV femtosecond laser to repair both opaque and clear defects with submicron
laser spot size while a proprietary gantry motion system supports nanometer-scale accuracy and stability for edge
lock. Key tool specifications, system architecture, design parameters, and laser processing specifics are discussed.
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