Focusing apparatus for projection optical system
AssigneeNippon Kogaku K. K.
InventorKyoichi Suwa
Life of this patent
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Abstract
A focusing apparatus for projection optical system is provided with a projection optical system and an image-forming optical system. The projection optical system is disposed to project an image of an alignment mark formed on a photo mask or reticle onto a light-reflective substrate and also to reverse-project onto the photo mask the light image of the alignment mark projected on and reflected by the substrate. The image-forming optical system forms an overlap image from the reverse-projected reflected image and the alignment mark on the photo mask.
Claims18
Apparatus for forming a light image of a photo pattern on a substrate member, said apparatus comprising:
- projection optical means disposed between said photo pattern and said substrate member for forming said light image;
- said substrate member having a light-reflective surface disposed to reflect the image-forming light from said projection optical means, the reflected light being incident upon said projection optical means and then directed to said photo pattern by said projection optical means;
- image-forming optical means for forming another light image of said photo pattern on a determined image plane, said reflected light after passing through said projection optical means and said photo pattern being directed to said another light image on said determined image plane through said image-forming optical means;
- means for positioning said substrate member in response to a distribution of light on said determined image plane so that said photo pattern and said reflective surface are conjugate with each other relative to said projection optical means;
- means for detecting a position of said reflective surface in a direction of an optical axis of said projection optical means to generate a detection signal;
- and
- means for calibrating said detecting means so that said detection signal is generated when said substrate member is positioned by said positioning means.
Apparatus for forming a light image of a photo pattern placed on a first plane on a second plane, said apparatus comprising:
- projection optical means disposed between said first and second planes for forming said light image;
- alignment mark means comprising a first mark provided on said photo pattern and a second mark provided on said second plane, said alignment mark means being used to attain the alignment in relative position between said photo pattern and said second plane;
- image-forming optical means for forming a light image of said first mark on a determined image plane, said image-forming optical means including adjustment means for focusing said light image of the first mark on said determined image plane;
- illumination means having a light source providing an illumination light beam illuminating said first and said second mark through said image-forming optical means and said projection optical means;
- and
- means for controlling the relative positional relation between said projection optical means and said second plane in a direction of an optical axis of said projection optical means so as to form said light image of the second mark on said determined image plane through said projection optical means and said image-forming optical means adjusted by said adjustment means.
Apparatus for forming a light image of a photo pattern placed on a first plane on a second plane, said apparatus comprising:
- projection optical means disposed between said first and second planes for forming said light image;
- alignment mark means comprising a first mark provided on said photo pattern and a second mark provided on said second plane, said alignment mark means being used to attain the alignment in relative position between said photo pattern and said second plane;
- image-forming optical means for forming a light image of said first mark on a determined image plane, said image-forming optical means including adjustment means for focusing said light image of the first mark on said determined image plane;
- and
- means for controlling the relative positional relation between said projection optical means and said second plane in a direction of an optical axis of said projection optical means, said controlling means controlling said positional relation so that said photo pattern and said second plane are not conjugate with each other relative to said projection optical means during said focusing by said adjustment means and controlling said positional relation so that said light image of the second mark is formed on said determined image plane through said projection optical means and said image-forming optical means adjusted by said adjustment means.
Dependencies are inferred from the claim text.