Optical Engineering · 1995 · 20 citations · 0 references
EngineeringManufacturing EngineeringMetrologyMicroelectromechanical SystemsMicrofabrication3D PrintingHolographyMask FabricationMicrofabrication MetrologyOptical MetrologyOptical PrintingAlignment TechniquesLithographic AlignmentMask Aligner LithographyMask Aligner TechnologyMask AlignmentMeasurement AccuracyOverlay AccuracyOverlay Alignment
Holographic mask aligners represent the latest addition to commercially available lithographic technologies. Their combination of very high resolution (< 0.5 μm) and very large exposure field brings a new capability to the microelectronics industry, especially for the manufacture of flat panel displays. The machine is fully automated and includes a scanning laser illumination system, a dynamic focus system permitting patterns to be printed over poor-flatness substrates, and an alignment system providing 0.3-μm overlay accuracy. A higher-accuracy alignment system under development demonstrates 50-nm measurement accuracy. A step-and-repeat hologram recording method enables tighter control of feature linewidth.