Focus measurement in projection exposure apparatus
AssigneeCanon Kabushiki Kaisha
InventorsYoshihiro Shiode, Izumi Tsukamoto, Hiroshi Morohoshi, Yoshio Kawanobe
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Abstract
A method of detecting focus information about an image projecting optical system includes performing mark projection through the optical system, and, based on illumination lights having different chief ray incidence directions, the mark projection is carried out so that mark images formed by the illumination lights, respectively, are superposed one upon another approximately upon an imaging plane, and detecting focus information about the optical system on the basis of information related to a deviation between the mark images superposed.
Claims48
A method of detecting focus information about an image projecting optical system, said method comprising the steps of:
- performing mark projection through the optical system and based on illumination lights having different chief ray incidence directions, the mark projection being carried out so that mark images formed by the illumination lights, respectively, are superposed one upon another approximately upon an imaging plane;
- and
- detecting focus information about the optical system on the basis of information related to a deviation between the mark images superposed.
An exposure apparatus, comprising:
- a projection optical system for projecting a reticle pattern onto a photosensitive substrate;
- and
- measuring means for measuring a best focus position of said projection optical system, said measuring means having a function for detecting focus information about said optical system on the basis of information related to a deviation between mark images produced by mark projection made through said projection optical system and being based on illumination lights having different chief ray incidence directions,
- wherein the mark projection is carried out so that mark images based on the illumination lights are superposed one upon another approximately on an imaging plane.
A device manufacturing method, comprising the steps of:
- performing mark projection through a projection optical system for projecting a reticle pattern onto a photosensitive substrate, and being based on illumination lights having different chief ray incidence directions, the mark projection being carried out so that mark images formed by the illumination lights, respectively, are superposed on upon another approximately upon an imaging plane;
- detecting focus information about the optical system on the basis of information related to a deviation between the mark images superposed;
- adjusting the projection optical system;
- projecting the pattern onto the photosensitive substrate through the adjusted projection optical system;
- and
- developing the photosensitive substrate, for formation of a circuit on the substrate.
A method of measuring an image plane of an image projection optical system, said method comprising the steps of:
- preparing plural marks in accordance with different image heights;
- performing mark projection in relation to each of the different image heights, made through the optical system and on the basis of illumination lights having different chief ray incidence angles;
- and
- detecting focus information of the optical system in relation to each of the different image heights, on the basis of information about a relative position between mark images as produced by the illumination lights,
- wherein the image plane measurement is performed on the basis of the focus information related to the different image heights.
An exposure apparatus, comprising:
- a projection optical system for projecting a reticle pattern onto a photosensitive substrate;
- and
- measuring means for measuring an image plane of said projection optical system, said measuring means having a function for detecting focus information about said optical system, in relation to each of different image height positions, on the basis of information related to a relative position of mark images produced by mark projection made through said projection optical system and being based on illumination lights having difference chief ray incidence directions.
A mask to be used in measurement for an image projecting optical system, said mask comprising:
- a transparent substrate;
- a plurality of marks provided on a surface of the substrate;
- and
- a light blocking portion and an opening portion formed on a surface opposite to a mark bearing surface of the substrate,
- wherein at least two marks and the opening portion are disposed so that, for projection of the marks through the optical system, the at least two marks are illuminated with illumination lights having different chief ray incidence angles.
A method of measuring astigmatism of a projection optical system, said method comprising the steps of:
- performing mark projection through the optical system and based on illumination light having different chief ray incidence directions;
- and
- detecting information about a deviation between mark images produced approximately on an imaging plane by the mark projection, wherein information related to the astigmatism of the optical system is detected on the basis of the deviation information.
An exposure apparatus, comprising:
- a projection optical system for projecting a reticle pattern onto a photosensitive substrate;
- and
- measuring means for measuring astigmatism of said projection optical system, said measuring means having a function for detecting information related to a deviation of mark images produced approximately on an imaging plane, by mark projection made through said projection optical system and being based on illumination lights having difference chief ray incidence directions.
A device manufacturing method, comprising the steps of:
- performing mark projection through a projection optical system for projecting a reticle pattern onto a photosensitive substrate, and being based on illumination lights having different chief ray incidence directions;
- detection information about a deviation of mark images to be produced approximately on an imaging plane, by the mark projection, wherein information related to the astigmatism of the optical system is detected on the basis of the deviation information;
- adjusting the optical system, on the basis of the astigmatism information;
- projecting the pattern onto the photosensitive substrate through the adjusted projection optical system;
- and
- developing the photosensitive substrate, for formation of a circuit on the substrate.
Dependencies are inferred from the claim text.