OFF-AXIS PROJECTION OPTICS SYSTEM AND EXTREME ULTRA VIOLET LITHOGRAPHY APPARATUS APPLYING THE SAME

摘要

Example embodiments are directed to an off-axis projection optical system including first and second mirrors that are off-axially arranged. The tangential and sagittal radii of curvature of the first mirror may be RSUB1t /SUBand RSUB1s/SUB, respectively. The tangential and sagittal radii of curvature of the second mirror may be RSUB2t /SUBand RSUB2s/SUB, respectively. The incident angle of the beam from an object point to the first mirror 10 may be iSUB1/SUB, and an incident angle of the beam reflected from the first mirror 10 to the second mirror 30 is iSUB2/SUB. The values of RSUB1t/SUB, RSUB1s/SUB, RSUB2t/SUB, RSUB2s/SUB, iSUB1 /SUBand iSUB2 /SUBmay satisfy the following Equation ?in-line-formulae description="In-line Formulae" end="lead"?RSUB1t /SUBcos iSUB1/SUB=RSUB2t /SUBcos iSUB2/SUB?in-line-formulae description="In-line Formulae" end="tail"? ?in-line-formulae description="In-line Formulae" end="lead"?RSUB1s/SUB=RSUB1t /SUBcosSUP2/SUPiSUB1/SUB?in-line-formulae description="In-line Formulae" end="tail"? ?in-line-formulae description="In-line Formulae" end="lead"?RSUB2s/SUB=RSUB2t /SUBcosSUP2/SUPiSUB2/SUB.?in-line-formulae description="In-line Formulae" end="tail"?