| 摘要 |
PURPOSE:To detect a position rapidly, by moving a stage linearly in the scanning direction which intersects the X direction and by detecting registering marks in the X and Y directions simultaneously. CONSTITUTION:A control unit 17 moves an optical axis obliquely in the 45 deg. direction along the line connecting the center CC of a chip and the point of intersection P0 of line segments l1 and l2. When a registering mark M passes across the light point LA along the scanning track SC, a photoelectric signal SA has the peak value. A processing circuit 16 processes a position data from a length measuring device 3 and the signal SA to detect the peak position coordinates x0 and y0. Thus, the positional relation between the optical axis and the point P0 can be determined. The processing circuit 16 outputs to the control unit 17 while the position of the mark M (x0+DELTAx, y0+DELTAy) where DELTAx and DELTAy are predetermined offsets for the mark M is set as the target value. The control unit 17 servo controls a table 2 such that the positional data PD reaches the target value. Consequently, the optical axis of the lenses is allowed to pass the center CC of the chip correctly and a wafer is aligned precisely. According to this construction, the marks Mx and My can be detected simultaneously, and therefore the position can be detected rapidly. |
