| 摘要 |
PURPOSE:To improve the degree of freedom in arranging marks on a mask, by providing a movable member moving in correspondence with a movement of alignment optical systems and providing a means for detecting a position of the movable member so as to enable a collision between the alignment optical systems to be sensed beforehand. CONSTITUTION:A block 7 housing an objective lens system 70 is attached on a Y stage 6 on an X stage 2. The optical axis OX of the lens system 70 is in parallel with a mask R and a light ray passing orthogonally to a mark Rm is made coincident with the optical axis OX by mirrors M1 and M2 attached to the end of a pivotable arm 15. A distance D from the end of the lens system 70 to the optical axis OX' is approximately coincident with a distance from the center to the periphery of a mask R. Sensing plates 8 and 9 movable similarly to the arm and the block are carried on the Y stage 6 by means of 10a and 10b so as to keep the distance from the center of the arm 15. A leaf spring is attached to the tip end of the sensing plate while a switch 11 is attached thereunder. The sensing plate 9 is applied against the switch to turn it OFF before light-hand and left-hand optical devices strike against each other and, thereby, driving sources 3 and 5 are stopped. During exposure, the arm 15 is lifted up. In this manner, the degree of freedom in arranging registering marks can be improved remarkably. |
