Catadioptric system and exposure apparatus having the same
First Claim
1. A catadioptric optical system for forming a reduced image of a pattern of a first surface on a second surface, said catadioptric optical system comprising a first lens group, a beam splitter, a concave mirror having an enlarging magnification, and a second lens group;
- wherein light from said first surface passes through said first lens group and said beam splitter, in this order, so as to be directed to said concave mirror, whereas light reflected by said concave mirror passes through said beam splitter and said second lens group, in this order, so as to be directed to said second surface;
wherein a rear-side principal point position of said second lens group is on said second surface side with respect to a light-entering surface of said second lens group on which the light having passed through said beam splitter is incident; and
wherein said catadioptric optical system satisfies the following conditions;
space="preserve" listing-type="equation">-1<
1/β
.sub.M <
0.5
space="preserve" listing-type="equation">0.85<
L.sub.1 /f.sub.2wherein β
M is imaging magnification of said concave mirror, L1 is distance between said rear-side principal point position and the light-entering surface of said second lens group, and f2 is focal length of said second lens group.
1 Assignment
0 Petitions
Accused Products
Abstract
This invention relates to a catadioptric optical system in which, a large numerical aperture is attained on the image side and, while securing a sufficient working distance, the size of the beam splitter is reduced, thereby attaining a resolution of a quarter micron unit, and an exposure apparatus using the same. In order to form a reduced image of a pattern of a first surface on a second surface, this catadioptric optical system comprises, at least, a first lens group, a beam splitter, a concave mirror having an enlarging magnification, and a second lens group. These constitutional elements of the catadioptric optical system are disposed such that light from the first surface passes through the first lens group, the beam splitter, the concave mirror, the beam splitter, and the second lens group in this order. In particular, the rear-side principal plane of the second lens group is on the second surface side with respect to a light-entering surface of the second lens group on which the light having passed through the beam splitter is incident. In addition, the concave mirror functions to collimate the light having passed through the beam splitter and then make thus collimated light re-enter the beam splitter.
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Citations
24 Claims
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1. A catadioptric optical system for forming a reduced image of a pattern of a first surface on a second surface, said catadioptric optical system comprising a first lens group, a beam splitter, a concave mirror having an enlarging magnification, and a second lens group;
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wherein light from said first surface passes through said first lens group and said beam splitter, in this order, so as to be directed to said concave mirror, whereas light reflected by said concave mirror passes through said beam splitter and said second lens group, in this order, so as to be directed to said second surface; wherein a rear-side principal point position of said second lens group is on said second surface side with respect to a light-entering surface of said second lens group on which the light having passed through said beam splitter is incident; and wherein said catadioptric optical system satisfies the following conditions;
space="preserve" listing-type="equation">-1<
1/β
.sub.M <
0.5
space="preserve" listing-type="equation">0.85<
L.sub.1 /f.sub.2wherein β
M is imaging magnification of said concave mirror, L1 is distance between said rear-side principal point position and the light-entering surface of said second lens group, and f2 is focal length of said second lens group. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A catadioptric optical system for forming a reduced image of a pattern of a first surface on a second surface, said catadioptric optical system comprising a first lens group, a prism type beam splitter, a concave mirror having an enlarging magnification, and a second lens group;
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wherein light from said first surface passes through said first lens group and said beam splitter, in this order, so as to be directed to said concave mirror, whereas light reflected by said concave mirror passes through said beam splitter and said second lens group, in this order, so as to be directed to said second surface; and wherein said catadioptric optical system satisfies the following conditions;
space="preserve" listing-type="equation">-1<
1/β
M<
0.5
space="preserve" listing-type="equation">0.85<
L.sub.1 /f.sub.2wherein β
M is imaging magnification of said concave mirror, L1 is distance between said rear-side principal point position and the light-entering surface of said Second lens group, and f2 is focal length of said second lens group. - View Dependent Claims (11, 12, 23, 24)
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13. A catadioptric optical system for forming a reduced image of a pattern of a first surface on a second surface, said catadioptric optical system comprising:
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a beam splitter having a direction change surface for changing a traveling direction of light input from a predetermined direction; a first lens group which is disposed in an optical path between said first surface and said beam splitter so as to guide light from said first surface to said beam splitter; a second lens group which is disposed in an optical path between said beam splitter and said second surface so as to guide light from said beam splitter to said second surface; and a collimator for collimating light which has passed through said first lens group and whose traveling direction is to be changed by the direction change surface of said beam splitter and guiding thus collimated light to said beam splitter from said predetermined direction, wherein said collimator includes a concave mirror having an enlarging magnification. - View Dependent Claims (14, 15, 16)
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17. An exposure apparatus comprising:
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a first stage allowing a photosensitive substrate to be held on a main surface thereof; a second stage for holding a mask having a predetermined pattern; an illumination optical system for illuminating said mask with exposure light having a predetermined wavelength so as to transfer an image of the pattern of said mask to said substrate; and a catadioptric optical system provided between said first stage and said second stage so as to project a reduced image of the pattern on said mask upon said substrate, said catadioptric optical system comprising; a beam splitter having a direction change surface for changing a traveling direction of light input from a predetermined direction; a first lens group which is disposed in an optical path between said mask and said beam splitter so as to guide light from said mask to said beam splitter; a second lens group which is disposed in an optical path between said beam splitter and said substrate so as to guide light from said beam splitter to said substrate; and a collimator for collimating light which has passed through said first lens group and whose traveling direction is to be changed by the direction change surface of said beam splitter and guiding thus collimated light to said beam splitter from said predetermined direction, wherein said collimator of said catadioptric optical system includes a concave mirror having an enlarging magnification. - View Dependent Claims (18, 19, 20, 22)
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21. An exposure apparatus comprising:
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a first stage allowing a photosensitive substrate to be held on a main surface thereof; a second stage for holding a mask having a predetermined pattern; an illumination optical system for illuminating said mask with exposure light having a predetermined wavelength so as to transfer an image of the pattern of said mask to said substrate; and a catadioptric optical system provided between said first stage and said second stage so as to project a reduced image of the pattern on said mask upon said substrate, said catadioptric optical system comprising; a beam splitter having a direction change surface for changing a traveling direction of light input from a predetermined direction; a first lens group which is disposed in an optical path between said mask and said beam splitter so as to guide light from said first surface to said beam splitter; a second lens group which is disposed in an optical path between said beam splitter and said substrate so as to guide light from said beam splitter to said substrate; and a concave mirror for reflecting light which has passed through said first lens group and whose traveling direction is to be changed by the direction change surface of said beam splitter and guiding thus reflected light to said beam splitter from said predetermined direction, wherein said catadioptric optical system satisfies the following conditions;
space="preserve" listing-type="equation">-<
1/β
.sub.M <
0.5
space="preserve" listing-type="equation">0.85<
L.sub.1 /f.sub.2wherein β
M is imaging magnification of said concave mirror, L1 is distance between said rear-side principal plane and the light-entering surface of said second lens group, and f2 is focal length of said second lens group.
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Specification