| 摘要 |
PURPOSE:To enable a table to be positioned without deteriorating the accuracy due to shifting, etc., of the table by a method wherein the table is positioned by using phase angles of Moire fringes, the distance of an object up to target positions as well as the position of the table at the time of measurement. CONSTITUTION:After reading out the position of Moire fringes on a frame memory 12 by an image sensor 7, Moire fringe base periodic component is extracted by Fourier analysis using a processor 16 to calculate the topological angle for checking the relative movements of a mask 20 and a wafer 14. The position of wafer table 15 whereon the mask 20 and the wafer 14 are overlapped each other on a specified position is constantly read out from an interferometer 9 to a driving circuit 10 while said position is calculated by an adder 18 to control a driving motor 13 for positioning the wafer table 15. Through these procedures, the mask 20 and the wafer 14 being subjected to position measurement can avert the effect of movement and vibration of wafer table 15 so that they may be overlapped each other in the specified position with high accuracy. |
