| 摘要 |
PURPOSE:To contrive to extract a signal for detection of position in a high speed and with high precision by a method wherein a pattern to be detected is enlarged to be projected together with a referential pattern, scanned according to slits, brightness of transmitted light is photoelectrically converted, converted according to A/D conversion synchronizing with a referential pulse, and a computing process is performed according to the signal of a memory. CONSTITUTION:When the positioning pattern 4 of a substrate and a referential pattern 2 on a reticle are enlarged to be projected on the scanning surface of slits 7 through optical systems 5, 6, the patterns 2 is bright and the pattern 4 is dark. The rotation of a drum 16 is controlled 17, the image of the pattern 4 is scanned at a fixed speed by the slits 7, brightness of transmitted light is photoelectrically converted 9, and converted 12 according to A/D conversion synchronizing with a referential pulse 19 to be stored 14. Moreover the number of the pulses are counted 13 from the original point passing time of the slit 7, converted according to A/D conversion, and stored 14. When the counted number of the pulses 19 is indicated by (i), frequency is by (f), the position of the slit is by Xi, the scanning speed is by (v), and magnification of projection is indicated by A, relation between them can be expressed by Xi=(v/fA)i, and the axis of ordinates indicates brightness of transmitted light. The relative position (DELTA) of the centers of coordinates of the patterns 2, 4 are operated 15 to be detected according to statistical technique from the output signals thereof. When (f) is increased, resolution can be made high, and extraction of the signal at position detecting time can be performed at a high speed with high precision. |
