Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
331 words
An improved apparatus for use in a microlithography system to align a semiconductor wafer having a plurality of dies, each die having fiducial marks, with the projected image of at least one pattern having further fiducial marks, said apparatus comprising : means (34-47) for directing a beam of light toward a reticle (20) ; shutter (43-44) means having an aperture (45) for permitting a fraction of said beam to illuminate the fiducial marks (28-30) of the reticle pattern ; a projection lens comprising : a spherical concave mirror (52) having an aperture (58) on its optical axis (51) ; a meniscus lens (53) having a first convex surface (D) facing said mirror and a concave surface (C) facing away from said mirror ; a plano-convex lens (55) having a second convex surface facing said concave surface (D) and a first flat surface (B) facing away from said mirror ; and first and second prisms (56, 57) for coupling light into and from separate fields on said first flat surface, each of said prisms having an optical path length and a second flat surface (A) facing one of the image and object planes of said projection lens, said image and object planes being spaced from said second flat surfaces, whereby said fraction of said beam passes through a reticle (20) positioned at the object plane to illuminate a wafer (10) positioned at the image plane ; means for moving a wafer (10) in said image plane to align the projected image of the fiducial marks of the reticle patterns with the further fiducial marks of a die on said wafer, and means (66) for detecting light scattered through said aperture (58) of said mirror (52) and for stopping said moving means when said protected image aligns with said further fiducial marks, characterized in that said shutter means comprises a filter for preventing passage of that portion of the spectrum of said beam normally used to expose a die (12) for microlithographic printing.
Claim 2
Dependent Claim
331 words
An improved apparatus for use in a microlithography system to align a semiconductor wafer having a plurality of dies, each die having fiducial marks, with the projected image of at least one pattern having further fiducial marks, said apparatus comprising : means (34-47) for directing a beam of light toward a reticle (20) ; shutter (43-44) means having an aperture (45) for permitting a fraction of said beam to illuminate the fiducial marks (28-30) of the reticle pattern ; a projection lens comprising : a spherical concave mirror (52) having an aperture (58) on its optical axis (51) ; a meniscus lens (53) having a first convex surface (D) facing said mirror and a concave surface (C) facing away from said mirror ; a plano-convex lens (55) having a second convex surface facing said concave surface (D) and a first flat surface (B) facing away from said mirror ; and first and second prisms (56, 57) for coupling light into and from separate fields on said first flat surface, each of said prisms having an optical path length and a second flat surface (A) facing one of the image and object planes of said projection lens, said image and object planes being spaced from said second flat surfaces, whereby said fraction of said beam passes through a reticle (20) positioned at the object plane to illuminate a wafer (10) positioned at the image plane ; means for moving a wafer (10) in said image plane to align the projected image of the fiducial marks of the reticle patterns with the further fiducial marks of a die on said wafer, and means (66) for detecting light scattered through said aperture (58) of said mirror (52) and for stopping said moving means when said protected image aligns with said further fiducial marks, characterized in that said shutter means comprises a filter for preventing passage of that portion of the spectrum of said beam normally used to expose a die (12) for microlithographic printing.
Claim 3
Dependent Claim
29 words
Apparatus according to claim 1, characterized in that said means for detecting comprises means for correcting for color shift introduced when said scattered light passes through said projection lens.
Claim 4
Dependent Claim
34 words
Apparatus according to claim 1, characterized in that said means for detecting comprises a plurality of apertures (70-72) selectively positionable to pass light scattered from fiducial marks on predetermined areas of said die (12).
Claim 5
Dependent Claim
57 words
Apparatus according to claim 1, characterized in that said means for detecting comprises mask means (68, 69) for blocking all scattered light except that from the area of a die (12) around the projected image of a fiducial mark on the reticle (20), and a photomultiplier (66) for detecting the intensity of light passing said mask means.
Claim 6
Dependent Claim
45 words
Apparatus according to claim 1, characterized in that said correcting means comprises means for shifting said scattered light away from said optical axis and lens means for receiving said scattered light after said shifting so that said scattered light passes off-center through said lens means.
Claim 7
Dependent Claim
104 words
Apparatus according to claim 1, characterized in that it comprises means including spaced apertures (70-72) selectively positionable to pass light scattered through said aperture (58) of said mirror (52) by said wafer means (10) from the projected image of the spaced fiducial marks of the reticle pattern ; means for moving the reticle (20) in the object plane to align the projected image of the spaced fiducial marks of the reticle pattern with said spaced apertures ; and means (66) for detecting light passed through said spaced apertures and for stopping said moving means when said projected image aligns with said spaced apertures (70-72).
Claim 8
Dependent Claim
36 words
Apparatus according to claim 6, characterized in that said means for detecting comprises a plurality of further apertures selectively positioned to pass light scattered from preselected projected images of the fiducial marks of the reticle pattern.