Lithographic apparatus and device manufacturing method

1. A lithographic apparatus comprising:

an illumination system for conditioning a beam of radiation;

an article support for supporting a substantially flat article to be placed in said beam of radiation, said article support comprising a plurality of supporting protrusions for supporting the article, a boundary substantially surrounding said supporting protrusions, and at least one protective member located near said boundary for protecting at least a boundary portion of said supporting protrusions during release of said article; and

a releasing device for releasing said article from said article support.

2. A lithographic apparatus according to claim 1 , wherein said protective member is formed by the boundary portion of said supporting protrusions, individual supporting protrusions within said boundary portion having a supporting area that is larger than a supporting area of individual supporting protrusions located away from said boundary.

3. A lithographic apparatus according to claim 2 , wherein the supporting area of the supporting protrusions gradually decreases as a distance of said protrusions to said boundary increases.

4. A lithographic apparatus according to claim 2 , wherein said supporting area of said supporting protrusions within said boundary portion ranges from 2–50 times said supporting area of said supporting protrusions located away from said boundary.

5. A lithographic apparatus according to claim 2 , wherein the plurality of said supporting protrusions individually comprise a base cylinder of a first diameter and a supporting top cylinder of a second diameter smaller or equal to said first diameter, wherein the top cylinders of the protrusions forming the protective member are larger in diameter than the top cylinders of the protrusions away from said boundary.

6. A lithographic apparatus according to claim 1 , wherein said protective member defines a first gap between said plane of support and said protective member, so that said protective member contacts said article only during the release of the article.

7. A lithographic apparatus according to claim 6 , wherein said protective member extends away from said boundary.

8. A lithographic apparatus according to claim 7 , wherein said protective member has a strip form.

9. A lithographic apparatus according to claim 6 , wherein the plurality of said supporting protrusions individually comprise a base cylinder of a first diameter and a supporting top cylinder of a second diameter that is smaller than said first diameter, wherein the top cylinder has a length equal to said first gap, so that said protective member is formed by said base cylinder of said protrusion.

10. A lithographic apparatus according to claim 6 , wherein said article support comprises a boundary wall adjacent to said plurality of supporting protrusions, said boundary wall providing a second gap between said plane of support and said wall for providing a leaking seal, said second gap being larger than said first gap.

11. A lithographic apparatus according to claim 10 , wherein said protective member traverses said boundary wall.

12. A lithographic apparatus according to claim 1 , wherein at least a part of said article support is coated with a wear resistant layer.

13. A lithographic apparatus according to claim 12 , wherein said wear resistant layer is a TiN coating.

14. A lithographic apparatus according to claim 1 , wherein said article support is a support for supporting a patterning device, the patterning device configured to pattern the beam of radiation.

15. A lithographic apparatus according to claims 1 , wherein said article support is a substrate table for holding a substrate to be patterned by a patterned beam of radiation.

16. A device manufacturing method comprising:

conditioning a beam of radiation;

supporting a patterning device with an article support, said patterning device configured to pattern the beam of radiation, said article support comprising a plurality of supporting protrusions;

projecting said patterned beam of radiation onto a substrate;

releasing said patterning device from said article support with a releasing device; and

protecting at least a boundary portion of said plurality of supporting protrusions during said release of said patterning device.

17. A device manufacturing method comprising:

conditioning a beam of radiation;

patterning the beam of radiation with a patterning device;

supporting a substrate with an article support, said article support comprising a plurality of supporting protrusions;

projecting said patterned beam of radiation onto a target portion of said substrate;

releasing said substrate from said article support with a releasing device; and

protecting at least a boundary portion of said plurality of supporting protrusions during said release of said substrate.

18. An article support for supporting a substantially flat article to be placed in a lithographic apparatus, said article support comprising:

a plurality of supporting protrusions for supporting the article;

a boundary substantially surrounding said supporting protrusions; and

at least one protective member located near said boundary for protecting at least a boundary portion of said supporting protrusions during release of said article.

19. An article support according to claim 18 , wherein said protective member is formed by the boundary portion of said supporting protrusions, individual supporting protrusions within said boundary portion having a supporting area that is larger than a supporting area of individual supporting protrusions located away from said boundary.

20. An article support according to claim 19 , wherein the supporting area of the supporting protrusions gradually decreases as a distance of said protrusions to said boundary increases.