| 摘要 |
PROBLEM TO BE SOLVED: To obtain a projection aligner constituted so that a reticle pattern can be projected and exposed on a semiconductor wafer with such a high-NA and wide exposure area of about NA 0.65 and the exposure area ofϕ27.3 mm achieved by using an aspherical surface. SOLUTION: This projection optical system is provided with plural lens groups including the lens groups having positive and negative refractive power and projecting the image of an object toward an image surface. When conjugate length is defined as L and the sum of the power of the respective negative lens groups is defined asψo, the expression that|L×ψo|<17ϕo=Σϕoi and (ϕoi) is the power of the (i)th negative lens group is obtained. When the height of an axial marginal light beam is defined as (h) and that of the most off-axis light beam is defined as (hb), at least two surfaces out of the surfaces satisfying the expression of|hb/h|>0.35 are formed to be aspherical and the aspherical surface amount of the aspherical surface is defined asΔASPH, the expression of|ΔASPH/L|>1.0×10-6 is satisfied. At least two aspherical surfaces are provided with such areas that the change of local curvature power are mutually reverse codes extending over the peripheral parts from the centers thereof. |
