| 摘要 |
PURPOSE:To prevent a wafer from shifting in position laterally even at the time of leveling after the stepping of a wafer stage responding to one shot by providing a specific leveling stage to a Z stage equipped with a plane mirror for an interferometer. CONSTITUTION:The Z stage 4 equipped with the plane mirror 8 for the interferometer 10 in two orthogonal directions on an XY stage 6 is provided with the leveling stage 2 where the wafer W is mounted. This stage 2 is provided with arm parts 2a formed of a radial bearing 26, a doughnut-shaped leaf spring 20a, etc., at intervals of 120 deg. and the wafer W is leveled through a motor-driven slanting nut 28. The spring 20a has its operation center point OA concentrically with a circular stage 2 and is coincident with a reference plane R in a neutral state, and the quantity of lateral shifting at the time of the bearing of the wafer W is an extremely small value represented by the cosine function of a tilt angle theta and ignored substantially. Consequently, the wafer never shifts in position laterally even at the bearing after the stepping of the wafer stage to one shot. |
