| 摘要 |
PROBLEM TO BE SOLVED: To realize a highly accurate alignment with a reduced noise component, by starting the operation for making a mask follow a photosensitive substrate, when the relative positional error between the mask with circuit patterns and the photosensitive substrate reaches a specific quantity. SOLUTION: A stage 2 of a reticle 1 with circuit patterns and a diffraction mark is connected with both an interferometer 43 and a motor 42, and a stage 5 of a wafer 4 with a diffraction mark is connected with both an interferometer 45 and a motor 46. An alignment light fed from a laser beam source 1 is projected on a bifocal optical system 21. Also, P and S polarized lights outgoing from the optical system 21 are imaged respectively on focuses 26a, 27a. The focuses 26a, 27a are made conjugate by a projection lens 3 respectively to imaging planes 26b, 27b coinciding with the surface of the wafer 4. Reflective diffraction lights fed from the diffraction marks of the reticle 1 and wafer 4 reach a photoelectric sensor 25. Sensing in a phase sensing system 40, the phase difference between the signal fed from the sensor 25 and a reference beat signal fed from a photoelectric sensor 19, the relative alignment of the reticle 1 with the wafer 4 is performed. |
