POSITION DETECTOR, ALIGNMENT METHOD, AND ALIGNER

摘要

PROBLEM TO BE SOLVED: To improve the alignment accuracy of a mask with a substrate by providing a stage having first and second areas for sine and search alignment and moving a substrate so as to position a mark to one of an index plate formed in the first area and a position corresponding to the first and second areas, and a processor which processes picture signals. SOLUTION: A wafer W is optically conjugately positioned to an index plate with respect to a synthesizing system composed of an objective lens 12 and an image forming lens 16 and the index plate 18 and the light receiving surface of a CCD 22 are conjugately arranged with respect to an image pickup lens 20. A reference mark FM is provided on a stage ST and used for measuring the distances between the projecting point of an index mark on the index plate 18 upon the wafer W and the projecting points of reticle alignment marks RM1 and RM2 on a reticle R upon the wafer W. Video signals from the CCD 22 are supplied to an analg-to-digital converter(ADC) and a processor reads digital waveform data stored in a RAM and performs prescribed waveform processing operation.