| 摘要 |
PURPOSE:To search for an optimum focusing position without being affected by means of a scribe line, etc., by making a beam for focusing incident on the arbitrary position of a wafer through the use of a beam passage adjusting mechanism which can move a beam incident point on the wafer in parallel along the surface of the wafer. CONSTITUTION:When a placing plate 1 is moved up and down to the optimum focusing position with respect to an exposing optical system, the beam from a light projecting element for the focusing 7 is made incident on the position of a P1-point just under the optical axis of an exposing optical system by optical paths l1 l2 l3, and a reflected beam is made incident on the specific point P3 of a focusing photodetector 8 by optical paths l4 l5 l6. When mirrors 10 and 13 are interlocked each other and moved in the directions of the arrows 17 and 18, by the driving of pulse motors 11 and 14, the beam from the light projecting element 7 is made incident on a P2-point by optical paths l1 l7 l8, and the reflected beam is made incident on the specific point P3 of the photodetector 8 by optical paths l9 l10 l6. In other words, the incident point to the photodetector 8 is the P3-point without being changed, and a reflecting point is horizontally moved from the P1-point to the P2-point along the surface of the wafer 3. Thus, the focusing is carried out by using the height of the position which is properly deviated from the center of the wafer 3, as refer ence. |
