| 摘要 |
PURPOSE:To keep the accuracy of a position, where an optical sensor is provided, regardless of the operation of an X-Y table, by facing the light emitting means and the light receiving means of the optical sensor, and supporting both means through a wafer, which is mounted on the X-Y table. CONSTITUTION:An X-Y table 4 has a structure, in which three tables are stacked at a lower stage 4a, a middle stage 4b and an upper stage 4c. When the upper table 4c is moved in the direction of an arrow X and comes to a position 4c', a wafer which is sucked and kept by the table 4c, comes to a position 1'. An alignment pattern 1b', which is provided on the wafer 1', faces an objective lens 5. Under this state, the middle table 4b' is precisely and finely moved in the direction of Y-Y', and the upper table 4c' is precisely and finely moved in the direction of an arrow X-X'. The alignment pattern 1b' of the wafer 1' is precisely aligned by an optical system including the objective lens 5. For example recess parts are provided in the top surface of the upper table 4c, and phototransistors 10-1 and 10-2 are provided at positions corresponding to a point P1 and a point P2. LEDs 11-1 and 11-2 are provided so as to face the transistors, respectively, and supported by supporting arms 12 with respect to the lower base member 4a. |
