Auto focus alignment and measurement system and method

Claim 2

Apparatus for focusing on an object plane, said apparatus comprising: first imaging means (18), movably disposed along an optical axis, for providing a first focal plane disposed toward the object plane; second imaging means (30), disposed along the optical axis on the opposite side of the first imaging means from the object plane, for providing a second focal plane disposed away from the object plane; focus detection means (36), disposed along the optical axis at the second focal plane, for indicating focus of an image of the object plane; and control means (99), coupled to the focus detection means, for moving the first imaging means along the optical axis to position the first focal plane in coincidence with the object plane.

Claim 3

Apparatus for positioning a first planar object with respect to a second planar object separated from the first planar object by a finite distance, said apparatus comprising: first imaging means (18), movably disposed along an optical axis, for providing a first focal plane disposed toward the planar objects; second imaging means (30), disposed along the optical axis on the opposite side of the first imaging means from the planar objects, for providing a second focal plane disposed away from the planar objects; focus detection means (36), disposed along the optical axis at the second focal plane, for indicating focus of images of the planar objects; control means, coupled to the focus detection means, for moving the first imaging means from one position to another along the optical axis to position the first focal plane alternately in coincidence with adjacent surfaces of the planar objects; and

Claim 4

Apparatus for positioning a first planar object with respect to a second planar object separated from the first planar object by a finite distance, said apparatus comprising: first imaging means (18), movably disposed along an optical axis, for providing a first focal plane disposed toward the planar objects; second imaging means (30), disposed along the optical axis on the opposite side of the first imaging means from the planar objects, for providing a second focal plane disposed away from the planar objects; focus detection means (36), disposed along the optical axis at the second focal plane, for indicating focus of images of the planar objects; control means, coupled to the focus detection means, for moving the first imaging means from one position to another along the optical axis to position the first focal plane alternately in coincidence with adjacent surfaces of the planar objects; and

Claim 5

processing means, coupled to the control means, for determining the displacement between the aforementioned positions of the first imaging means, to determine the separation distance between the adjacent surfaces of the planar objects, said displacement being equal to the separation distance between those adjacent surfaces along the optical axis.

Claim 6

processing means, coupled to the control means, for determining the displacement between the aforementioned positions of the first imaging means, to determine the separation distance between the adjacent surfaces of the planar objects, said displacement being equal to the separation distance between those adjacent surfaces along the optical axis.

Claim 7

Apparatus as in claim 2 further comprising: displacement means for moving the first planar object in a direction parallel to the optical axis; and control means,coupled to the displacement means, for adjusting the separation distance between the adjacent surfaces of the planar objects to a preselected value.

Claim 8

Apparatus as in claim 2 further comprising: displacement means for moving the planar objects together in a plane perpendicular to the optical axis to allow determination of the separation distance between the adjacent surfaces of the planar objects at several locations; and rotation means for rotating the first planar object about orthogonal axes perpendicular to the optical axis to position the adjacent surfaces of the planar objects in parallel planes by equalizing the separation distances determined at the aforementioned locations.

Claim 9

Apparatus as in claim 3 or 4 further comprising: displacement means for translating and rotating the first planar object relative to the second planar object in a plane perpendicular to the optical axis; alignment sensing means for measuring the alignment between the two planar objects; and control means, coupled to the alignment sensing means and to the last-mentioned displacement means, for controlling the translation and rotation of the first planar object to position the first planar object in alignment with respect to the second planar object.

Claim 10

Apparatus for measuring the degree of flatness of a generally planar object, said apparatus comprising: first imaging means, movably disposed along an optical axis, for providing a first focal plane disposed toward the planar object: second imaging means, disposed along the optical axis on the opposite side of the first imaging means from the planar object, for providing a second focal plane disposed away from the planar object; focus detection means, disposed along the optical axis at the second focal plane, for indicating focus of an image of the planar object; displacement means for moving the planar object in a plane parallel to the first focal plane to successively position different areas of the planar object within the field of view of the first imaging means; control means, coupled to the focus detection means, for moving the first imaging means to successively position the first focal plane in coincidence with the aforementioned areas of the planar object; and processing means, coupled to the control means, for determining the displacement range of the first imaging means for the aforementioned areas of the planar object to determine the degree of flatness of the planar object.

Claim 11

Apparatus for measuring the degree of flatness of a generally planar object, said apparatus comprising: first imaging means, movably disposed along an optical axis, for providing a first focal plane disposed toward the planar object: second imaging means, disposed along the optical axis on the opposite side of the first imaging means from the planar object, for providing a second focal plane disposed away from the planar object; focus detection means, disposed along the optical axis at the second focal plane, for indicating focus of an image of the planar object; displacement means for moving the planar object in a plane parallel to the first focal plane to successively position different areas of the planar object within the field of view of the first imaging means; control means, coupled to the focus detection means, for moving the first imaging means to successively position the first focal plane in coincidence with the aforementioned areas of the planar object; and processing means, coupled to the control means, for determining the displacement range of the first imaging means for the aforementioned areas of the planar object to determine the degree of flatness of the planar object.

Claim 12

Apparatus for aligning a semiconductor substrate with respect to a circuit mask separated from the substrate by a finite distance, said apparatus comprising: first imaging means, movably disposed along a first optical path, for providing a first focal plane disposed toward the mask and the substrate; second imaging means, disposed along the first optical path on the opposite side of the first imaging means from the mask and the substrate, for providing a second focal plane disposed away from the mask and the substrate; beam splitting means, disposed along the first optical path between the first imaging means and the second imaging means, for providing a second optical path; third imaging means,disposed along the second optical path, for providing an image of the mask and the substrate; focus detection means, disposed along the first optical path at the second focal plane, for indicating focus of images of the mask and the substrate; and control means, coupled to the focus detection means, for moving the first imaging means from one position to another along the first optical path to position the first focal plane alternately in coincidence with a surface of the mask and an adjacent surface of the substrate.

Claim 13

Apparatus for aligning a semiconductor substrate with respect to a circuit mask separated from the substrate by a finite distance, said apparatus comprising: first imaging means, movably disposed along a first optical path, for providing a first focal plane disposed toward the mask and the substrate; second imaging means, disposed along the first optical path on the opposite side of the first imaging means from the mask and the substrate, for providing a second focal plane disposed away from the mask and the substrate; beam splitting means, disposed along the first optical path between the first imaging means and the second imaging means, for providing a second optical path; third imaging means,disposed along the second optical path, for providing an image of the mask and the substrate; focus detection means, disposed along the first optical path at the second focal plane, for indicating focus of images of the mask and the substrate; and control means, coupled to the focus detection means, for moving the first imaging means from one position to another along the first optical path to position the first focal plane alternately in coincidence with a surface of the mask and an adjacent surface of the substrate.

Claim 14

Apparatus as in claim 7 further comprising illumination means for illuminating the aforementioned surface of the mask when that surface is in coincidence with the first focal plane and for illuminating the aforementioned adjacent surface of the substrate when that surface is in coincidence with the first focal plane.

Claim 15

Apparatus as in claim 8 further comprising first substrate displacement means for translating and rotating the substrate relative to the mask in a plane parallel to the first focal plane to move the substrate into alignment with respect to the mask.

Claim 16

Apparatus as in claim 7, 8 or 9 further comprising processing means, coupled to the control means, for determining the displacement between the aforementioned positions of the first imaging means to determine the separation distance between the aforementioned adjacent surfaces of the mask and the substrate, said displacement being equal to the separation distance between those adjacent surfaces along the first optical path.

Claim 17

Apparatus as in claim 10 further comprising: second substrate displacement means for moving the substrate in a direction perpendicular to the first focal plane; and control means, coupled to the second substrate displacement means and the processing means,for adjusting the separation distance between the adjacent surfaces of the substrate and the mask to a preselected value.

Claim 18

Apparatus for aligning a semiconductor substrate with respect to a circuit mask separated from the substrate by a finite distance, said apparatus comprising: right first imaging means, movably disposed along a right first optical path, for providing a right first focal plane disposed toward the mask and the substrate; left first imaging means, movably disposed along a left first optical path parallel to the right first optical path, for providing a left first focal plane disposed toward the mask and the substrate: right second imaging means, disposed along the right first optical path on the opposite side of the right first imaging means from the mask and the substrate, for providing a right second focal plane disposed away from the mask and the substrate; left second imaging means, disposed along the left first optical path on the opposite side of the left first imaging means from the mask and the substrate, for providing a left second focal plane disposed away from the mask and the substrate; right beam splitting means, disposed along the right first optical path between the right first imaging means and the right second imaging means, for providing a right second optical path separate from the right first optical path; left beam splitting means, disposed along the left first optical path between the left first imaging means and the left second imaging means, for providing a left second optical path separate from the left first optical path: right third imaging means, disposed along the right second optical path, for providing an image of a right area of a surface of the mask and a corresponding right area of an adjacent surface of the substrate; left third imaging means, disposed along the left second optical path, for providing an image of a left area of a surface of the mask and a corresponding left area of an adjacent surface of the substrate; right focus detection means, disposed along the right first optical path at the right second focal plane, for indicating focus of images of the corresponding right areas of the aforementioned adjacent surfaces of the mask and the substrate; left focus detection means, disposed along the left first optical path at the left second focal plane, for indicating focus of images of the corresponding left areas of the aforementioned adjacent surface3of the mask and the substrate; right control means, coupled to the right focus detection means, for moving the right first imaging means from one position to another along the right first optical path to position the right first focal plane alternately in coincidence with the corresponding right areas of the aforementioned adjacent surfaces of the mask and the substrate; and left control means, coupled to the left focus detection means, for moving the left first imaging means from one position to another along the left first optical path to position the left first focal plane alternately in coincidence with the corresponding left areas of the aforementioned adjacent surfaces of the mask and the substrate.

Claim 19

Apparatus for aligning a semiconductor substrate with respect to a circuit mask separated from the substrate by a finite distance, said apparatus comprising: right first imaging means, movably disposed along a right first optical path, for providing a right first focal plane disposed toward the mask and the substrate; left first imaging means, movably disposed along a left first optical path parallel to the right first optical path, for providing a left first focal plane disposed toward the mask and the substrate: right second imaging means, disposed along the right first optical path on the opposite side of the right first imaging means from the mask and the substrate, for providing a right second focal plane disposed away from the mask and the substrate; left second imaging means, disposed along the left first optical path on the opposite side of the left first imaging means from the mask and the substrate, for providing a left second focal plane disposed away from the mask and the substrate; right beam splitting means, disposed along the right first optical path between the right first imaging means and the right second imaging means, for providing a right second optical path separate from the right first optical path; left beam splitting means, disposed along the left first optical path between the left first imaging means and the left second imaging means, for providing a left second optical path separate from the left first optical path: right third imaging means, disposed along the right second optical path, for providing an image of a right area of a surface of the mask and a corresponding right area of an adjacent surface of the substrate; left third imaging means, disposed along the left second optical path, for providing an image of a left area of a surface of the mask and a corresponding left area of an adjacent surface of the substrate; right focus detection means, disposed along the right first optical path at the right second focal plane, for indicating focus of images of the corresponding right areas of the aforementioned adjacent surfaces of the mask and the substrate; left focus detection means, disposed along the left first optical path at the left second focal plane, for indicating focus of images of the corresponding left areas of the aforementioned adjacent surface3of the mask and the substrate; right control means, coupled to the right focus detection means, for moving the right first imaging means from one position to another along the right first optical path to position the right first focal plane alternately in coincidence with the corresponding right areas of the aforementioned adjacent surfaces of the mask and the substrate; and left control means, coupled to the left focus detection means, for moving the left first imaging means from one position to another along the left first optical path to position the left first focal plane alternately in coincidence with the corresponding left areas of the aforementioned adjacent surfaces of the mask and the substrate.

Claim 20

Apparatus as in claim 12 further comprising: right illumination means for illuminating the right area of the aforementioned surface of the mask when that area is in coincidence with the right first focal plane and for illuminating the right area of the aforementioned adjacent surface of the substrate when that area is in coincidence with the right first focal plane; and left illumination means for illuminating the left area of the aforementioned surface of the mask when that area is in coincidence with the left first focal plane and for illuminating the left area of the aforementioned adjacent surface of the substrate when that area is in coincidence with the left first focal plane.

Claim 21

Apparatus as in claim 13 further comprising first substrate displacement means for translating and rotating the substrate relative to the mask in a plane perpendicular to the right and left first optical paths to move the substrate into alignment with respect to the mask.

Claim 22

Apparatus as in claim 14 further comprising: processing means, coupled to the right and left control means, for determining the displacement between the aforementioned positions of the right first imaging means to determine the right separation distance between the corresponding right areas of the aforementioned adjacent surfaces of the mask and the substrate and for determining the displacement between the aforementioned positions of the left first imaging means to determine the left separation distance between the corresponding left areas of the aforementioned adjacent surfaces of the mask and the substrate; second substrate displacement means for rotating the substrate about an axis perpendicular to the right and left first optical paths; and control means, coupled to the second substrate displacement means and the processing means, for rotating the substrate to equalize the right and left separation distances.

Claim 23

Apparatus as in any of the preceding claims 1, 2, 6, 7 and 12 wherein each first imaging means comprises a single convergent lens.

Claim 24

Apparatus as in claim 16 wherein each second imaging means comprises a convergent lens.

Claim 25

Apparatus as in claim 17 wherein each second imaging means further comprises a convergent magnifying lens.

Claim 26

Apparatus as in any of the preceding claims 1, 2, 6, 7 and 12 wherein each control means comprises: a piezoelectric transducer, coupled to the respective first imaging means, for displacing that first imaging means in proportion to the magnitude of an applied voltage; and drive means, coupled to the piezoelectric transducer and the respective focus detection means, for driving the piezoelectric transducer with an applied voltage of a magnitude for effecting displacement of the respective first imaging means to a position at which the respective focus detection means indicates focus of the aforementioned image.

Claim 27

Apparatus as in claim 7 or 12 wherein each third imaging means comprises first and second convergent lenses for providing a focused and magnified view of the mask and the substrate.

Claim 28

Apparatus as in claim 7 or 12 wherein each third imaging means comprises a television camera and an associated television monitor for providing a focused and magnified view of the mask and the substrate.

Claim 29

Apparatus as in claim 8 or 13 wherein each illumination means comprises a strobe light timed to flash when a first focal plane coincides with the aforementioned surface of the mask or the aforementioned adjacent surface of the substrate.

Claim 36

A method as in claim 25 further comprising the step of measuring the displacement of the first optical lens from a position at which the image of the first planar object is focused at the focal plane of the second optical lens to a position at which the image of the second planar object is focused at the focal plane of the second optical lens to determine the separation distance between the first and second planar objects.

Claim 37

A method as in claim 26 further comprising the step of moving the first planar object in a direction parallel to the optical axis of the first optical lens to adjust the separation distance between the first and second planar objects to a preselected value.

Claim 38

A method as in claim 26 or 27 further comprising the steps of: measuring the separation distance between the first and second planar objects at a plurality of spaced-apart locations; and rotating the first planar object about orthogonal axes perpendicular to the optical axis of the first optical lens to equalize the separation distances measured at the aforementioned locations.

Claim 41

A method as in claim 25, 26, 27 or 29 wherein: the first planar object comprises a semiconductor substrate; and the second planar object comprises a circuit mask.