| 摘要 |
PURPOSE:To position objects rapidly and with high accuracy, by a method in which a correction is performed without proceeding to a high-accuracy measurement when a deflection obtained by a low-accuracy measurement is large, while the high-accuracy measurement is performed for correcting the deflection only when the deflection obtained by the low-accuracy is small. CONSTITUTION:Positional indices of objects to be positioned with each other are scanned once to determine a deflection with low accuracy at 104. It is judged whether the first deflection lies in a range for switching measuring accuracies at 105. If the first deflection lies in that range, the positional indices of the objects are scanned further several times so that a second deflection is determined with high precision at 106 by averaging the values obtained by the several scannings. Subsequently, it is judged whether the second deflection lies in target accuracies at 107. If the second deflection lies therein, the alignment procedures are finished at 110. If it is not, the relative position of the objects is readjusted at 108, and the high-accuracy measurement 106 and the readjustment 108 are repeated until the second deflection lies in the target accuracies can be obtained. If the first deflection is outside the range for switching the measuring accuracies, the relative position of the objects is readjusted at 108, and the low-accuracy measurement 104 and the readjustment 108 are repeated until the first deflection comes in that range can be obtained. |
