| 摘要 |
PURPOSE:To previously detect a partial out-of-focus prior to exposing by measuring the heights of an object to be measured in the respective positions thereof by inclinations of angle detectors, thereby detecting the flatness of the object to be measured. CONSTITUTION:Focusing is first executed by an LED 18, lenses 19, 20, and a detector 21 constituting the conventional autofocus detection mechanism. The heights at the points (a), (b) on a wafer 16 are then measured by an LED 11a, a detector 12a, polarizing plates 13c, 13d, and the angle detectors 14a, 14b. The heights at the points (c), (d) on the wafer 16 are measured by an LED 11b, a detector 12b, the polarizing plates 13c, 13d, and the angle detectors 14c, 14d. The results of the measurements at the above-mentioned points (a)-(d) and the results of the measurements by the conventional detector 21 are compared by a comparator 22, by which the presence or absence of the out-of-focus is judged. An instruction is given to a central processing unit if there is the out-of-focus. Exposing is executed if there is no out-of-focus. |
