| 摘要 |
PURPOSE:To measure the gap on-line between a mask and a wafer subject to non-destruction and non-contact by a method wherein the gap between a pattern and a mirror is set up by measuring any positional deflection caused when a pattern and a vertical image of pattern on the mirror are observed in the oblique direction. CONSTITUTION:A wafer 2 below a mask 1 is vacuum-adsorbed on a wafer chuck 3 for setting up by vacuum 5. The wafer chuck 3 controls the wafer 2 set thereon by vertical inching mechanisms 4-1, 4-2 to make specified gap between the wafer 2 and the mask 1. The gap shall be set up with high precision since the gap between the mask 1 and the wafer 2 is radially irradiated with X-rays from a spot type exposure light source so that any transferred pattern width may change in response to the change in gap between the mask 1 and the wafer 2. Therefore, an illumination optical system 6, a detection optical system 7 and a pattern detector 8 are provided to measure the gap. In such a constitution, the gap between the mask 1 and the wafer 2 detected by the pattern detector 8 can be fedback to the vertical inching mechanisms 4-1, 4-2 to set up the gap with high precision. |
