Illuminating optical system in an exposure apparatus

Claim 2

Apparatus including an illuminating optical system for illuminating an area of an object with light that is substantially equally spatially coherent along different directions in said area, said system comprising: means for producing a beam of light having spatial coherence that is different along different directions perpendicular to a propagation direction of said beam: means for dividing said beam into a plurality of beams; means for rotating at least one of said plurality of beams relative to the others about an axis substantially parallel to the direction of propagation thereof; and means for superposing said plurality of beams, including the at least one rotated beam, upon said area of said object; said rotating means rotating said at least one beam by an amount that causes light illuminating said area to have substantially equal spatial coherence along different directions in said area.

Claim 3

Apparatus according to claim 1, wherein said dividing means divides the produced beam into first and second beams, and said rotating means rotates said first and second beams relative to each other by about 90°.

Claim 4

Apparatus according to claim 2, wherein said rotating means includes a beam rotator provided in an optical path of said first beam.

Claim 5

Apparatus according to claim 3, wherein said beam rotator rotates the polarization of said first beam by about 90°, and said superposing means includes a polarizing beam splitter to which the rotated first beam and the second beam are applied, and further comprising a half-wave plate in the path of said rotated first beam before that beam is applied to said polarizing beam splitter.

Claim 6

Apparatus according to claim 1, wherein said dividing means includes a polarizing beam splitter which divides the produced beam according to directions of polarization thereof.

Claim 7

Apparatus according to claim 1, wherein said illuminating optical system comprises means for providing a substantially uniform light intensity distribution throughout said area of said object.

Claim 8

Apparatus according to claim 6, wherein said means for providing substantially uniform light intensity distribution follows said superposing means.

Claim 9

Apparatus according to claim 1, wherein the produced light beam has a substantially rectangular cross section in which the spatial coherence is different along orthogonal cross sectional directions.

Claim 10

Apparatus according to claim 8, wherein said illuminating optical system includes means for converting said substantially rectangular cross section to a substantially square cross section.

Claim 11

Apparatus according to claim 1, wherein said light beam producing means comprises a laser.

Claim 12

Apparatus according to claim 1, wherein said apparatus is an exposure apparatus for transferring a pattern provided on said area of said object onto a workpiece, and wherein said exposure apparatus includes a projection lens system having means for projecting an image of the illuminated area of said object onto said workpiece.

Claim 13

An exposure apparatus for transferring a pattern provided on an area of an object onto a workpiece, said exposure apparatus including an illuminating optical system for illuminating said area with light that is substantially equally spatially coherent along different directions in said area, said system comprising: means for producing a beam of light having spatial coherence that is different along different directions perpendicular to a propagation direction of said beam: means for dividing said beam into a plurality of beams; means for rotating at least one of said plurality of beams relative to the others about an axis substantially parallel to the direction of propagation thereof; and means for superposing said plurality of beams, including the at least one rotated beam, upon said area of said object; said rotating means rotating said at least one beam by an amount that causes light illuminating said area to have substantially equal spatial coherence along different directions in said area.

Claim 14

An exposure apparatus for transferring a pattern provided on an area of an object onto a workpiece, said exposure apparatus including an illuminating optical system for illuminating said area with light that is substantially equally spatially coherent along different directions in said area, said system comprising: means for producing a beam of light having spatial coherence that is different along different directions perpendicular to a propagation direction of said beam: means for dividing said beam into a plurality of beams; means for rotating at least one of said plurality of beams relative to the others about an axis substantially parallel to the direction of propagation thereof; and means for superposing said plurality of beams, including the at least one rotated beam, upon said area of said object; said rotating means rotating said at least one beam by an amount that causes light illuminating said area to have substantially equal spatial coherence along different directions in said area.

Claim 15

An exposure apparatus according to claim 12, wherein said exposure apparatus comprises a projection lens system including means for projecting an image of the illuminated area of said object onto said workpiece.

Claim 16

An exposure apparatus according to claim 12, wherein said dividing means divides the produced beam into first and second beams, and said rotating means rotates said first and second beams relative to each other by about 90°.

Claim 17

An exposure apparatus according to claim 14, wherein said rotating means includes a beam rotator provided in an optical path of said first beam.

Claim 18

An exposure apparatus according to claim 15, wherein said beam rotator rotates the polarization of said first beam by about 90°, and said superposing means includes a polarizing beam splitter to which the rotated first beam and the second beam are applied, and further comprising a half-wave plate in the path of said rotated first beam before that beam is applied to said polarizing beam splitter.

Claim 19

An exposure apparatus according to claim 12, wherein said dividing means includes a polarizing beam splitter which divides the produced beam according to the directions of polarization thereof.

Claim 20

An exposure apparatus according to claim 12, wherein said illuminating optical system comprises means for providing a substantially uniform light intensity distribution throughout said area of said object.

Claim 21

An exposure apparatus according to claim 18, wherein said means for providing substantially uniform light intensity distribution follows said superposing means.

Claim 22

An exposure apparatus according to claim 12, wherein the produced light beam has a substantially rectangular cross section in which the spatial coherence is different along orthogonal cross sectional directions.

Claim 23

An exposure apparatus according to claim 20, wherein said illuminating optical system includes means for converting said substantially rectangular cross section to a substantially square cross section.

Claim 24

An exposure apparatus according to claim 12, wherein said light beam producing means comprises a laser.