Importance

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Abstract

Position-detection apparatus (alignment sensors) are disclosed for determining the position of an object (e.g., wafer, bearing a position-detection mark) as required in microlithography processes for manufacturing semiconductor devices and displays. The apparatus comprises an irradiation optical system, a condenser optical system, a first photoelectric detector, a fiducial body bearing a fiducial mark, a combining optical system, a second photoelectric detector, and a processor. The position-detection and fiducial marks are illuminated with coherent illumination light from the irradiation optical system. Light diffracted from the marks is condensed by the condenser optical system. The first photoelectric detector receives the condensed diffracted light and produces first electrical signals. The combining optical system receives the diffracted light from the fiducial mark. The second photoelectric detector receives multiple diffracted light beams from the fiducial mark and produces second electrical signals. From the electrical signals, the processor determines the position of the position-detection mark relative to the fiducial mark.

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First Claim