| 摘要 |
PURPOSE:To achieve the position control of rapid response and good accuracy by providing the first position detector for setting plural drive quantities and the second position detector which corresponds to driving sources for feedback control of the plural driving sources. CONSTITUTION:The piezoelectric elements 23a, 23b and 23c (virtually, the element is formed by plurality of piezoelectric element chips laminated) arranged by equal angles through a wafer chuck base 21 are driven to move a wafer chuck 20 vertically in Z-direction (23c is not shown in the drawing.) Eddy current type position detectors 22a, 22b and 22c are attached in the position corresponding to each of the piezoelectric elements 23a, 23b and 23c and distances between overhangs of driving shafts of piezoelectric elements and the wafer chuck base 21 are measured thereby measuring the driving quantity of the piezoelectric elements. Also, nozzles 25a, 25b and 25c of an air microsensor are attached to the side part of a reduced projection lens 3 and the distances between the nozzles and the surface of the wafer are measured according to the change of backpressure or flow of the air blown off from the nozzle. |
