Catadioptric system and exposure apparatus having the same

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;

• 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;
• -1<1/.beta.M<0.5
• 0.85<L.sub.1 /f.sub.2
• wherein .beta..sub.M is imaging magnification of said concave mirror, L.sub.1 is distance between said rear-side principal point position and the light-entering surface of said Second lens group, and f.sub.2 is focal length of said second lens group.

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 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.

An exposure apparatus comprising:

• 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.

An exposure apparatus comprising:

• 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:
• -<
• 1/.beta..sub.M <0.5
• 0.85<L.sub.1 /f.sub.2
• wherein .beta..sub.M is imaging magnification of said concave mirror, L.sub.1 is distance between said rear-side principal plane and the light-entering surface of said second lens group, and f.sub.2 is focal length of said second lens group.