| 摘要 |
PURPOSE: To obtain a device with which position detection with high accuracy is possible even for alignment marks having a low difference in level by detecting the position of the marks in accordance with the first position information of the mark image in a first defocusing state and the second position information of the mark image in a second defocusing state. CONSTITUTION: The marks of the low difference in level having a height of, for example, several 10nm or below are commanded via a keyboard 26 in such a manner that the luminous flux for illumination regulated by a means 27 for regulating the opening state of illumination has the smallest possible illumination. The first position information of the mark image is detected in the first defocusing state in which the contrast higher than the best focusing state is obtainable. The second position information of the mark image is similarly detected in the second defocusing state in which the contrast higher than the contrast in the best focusing state is obtainable. As a result, the influence of the displacement of the telecentric property in accordance with the first and the second position information according to the first and the second defocusing state is corrected and the detection of the mark positions with the high accuracy is made possible. |
