| 摘要 |
PURPOSE:To make it possible to improve aligning accuracy and to perform highly accurate pattern printing at high resolution by providing wafer holding grooves and radial grooves, which are arranged from the vicinity of the center of the upper surface of a wafer mounting stage to the vicinity of the inside of an outer edge, on the upper surface of the wafer mounting table so that the grooves are communicated to vacuum sources. CONSTITUTION:On the upper surface of a wafer mounting stage 20 constituting a wafer chuck 1, a plurality of concentric grooves 3 are formed. Two radial grooves 2 are formed from the vicinity of the center of the stage 20 to the inside part of the outer edge of the stage 20. The two radial grooves 2 are formed symmetrically with respect to the center C and communicated to a vacuum source by way of a through hole 4. The concentric grooves 3 are communicated to a vacuum source by way of a through hole 14. When vacuum pressure is applied to the radial grooves 2 and the concentric grooves 3 through solenoid valves 8 and 18, a wafer 5 is adequately deformed at the parts of the radial grooves 2, and gas between the wafer 5 and a mask 6 is escaped. Thus the yield of a gap trap is prevented. At this time, since the width of the groove is small at the part of the concentric groove 3, the wafer 5 is hardly deformed. Therefore, adhesion degree between the mask 6 and the wafer 5 is improved, and highly accurate pattern printing at high resolution can be performed. |
