| 摘要 |
PURPOSE:To detect the position of a mark in a short time by each adding the density data of a TV picture in the X direction and the Y direction and detecting the direction of displacement of a relative position with a pattern for detecting positions on the basis of the data. CONSTITUTION:A wafer is held at a predetermined position, and moved up to a position where an alignment mark on the wafer enters in the visual field of an objective for pre-aligning a TV. The mark is detected by a pickup tube. A detected video signal is digitized 32, outputted to an addition block Y in the Y direction and an addition block X in the X direction, each added by adders 34, 38, and each made to be contained in a Y integrating memory 36 and an X integrating memory 40. When a fixed number of frames are added completely, the accesses of the memories 36 and 40 are executed, and read data are read to a microprocessor through a data bus 44. The microprocessor detects the direction of relative positional displacement with a pattern for detecting positions on the basis of integrated picture density data at a plurality of positions, and moves the wafer in the detecting direction. |
