| 摘要 |
PROBLEM TO BE SOLVED: To obtain a projection aligner whose AN is about 0.65 an which realizes an exposure area being aboutϕ27.3 mm, has a wide exposure area having the high NA and can project and expose a reticle pattern on a semiconductor wafer by using an aspherical surface. SOLUTION: This projection optical system for projecting an object image to an image surface is provided with 1st, 2nd, 3rd, 4th and 5th lens groups L1 to L5 having positive, negative, positive, negative and positive refractive power in this order from the object side. Assuming that the height of an on-axis marginal light beam is (h) and the height of the highest off-axis main light beam is hb, at least two of surfaces satisfying|hb/h|>0.35 are set as the aspherical surfaces, and assuming that the maximum aspherical amount from an optical axis to the effective diameter of the lens isΔASPH and the distance between the object images is L, the two aspherical surfaces satisfy|ASPH/ L|>1×10-6, and the system has an area where the change of local curvature power shows reverse sign to each other from the center of the surface to the peripheral part.
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