Lithographic apparatus, article support member, and method

1. A lithographic apparatus comprising:

an illumination system arranged to provide a radiation beam;

an article support member configured to support an article to be placed in a beam path of said radiation beam on said article support member; and

a clamp configured to provide a clamping pressure to clamp said article against said article support member, wherein said article support member comprises a trimmed section configured to locally adjust said clamping pressure.

2. A lithographic apparatus according to claim 1 , wherein said trimmed section comprises at least one protrusion constructed to support said article or to provide a boundary of a pressure zone between said article and said article support member.

3. A lithographic apparatus according to claim 2 , wherein said protrusion comprises a cut out region that expands to an upper surface of said protrusion.

4. A lithographic apparatus according to claim 1 , wherein said trimmed section comprises a carved section obtained by cutting, milling or drilling.

5. A lithographic apparatus according to claim 1 , wherein said clamp comprises an electrostatic clamp comprising an electrode and a dielectric layer covering said electrode, wherein said dielectric layer is trimmed so as to vary a local thickness of said layer.

6. A lithographic apparatus according to claim 1 , wherein said article support member is a support configured to support a patterning device, said patterning device serving to impart said beam with a pattern in its cross-section.

7. A lithographic apparatus according claim 1 , wherein said article support member is a substrate table configured to support a substrate to be patterned by a patterned beam onto a target portion of said substrate.

8. An article support member configured to support an article; said article support member comprising:

a clamp configured to provide a clamping pressure to clamp the article against said article support member, and

wherein said article support member comprises a trimmed section configured to locally adjust said clamping pressure.

9. An article support member according to claim 8 , wherein said trimmed section comprises a protrusion that has a trimmed side wall, so that said protrusion has a geometric center that is moved with respect to a non-trimmed protrusion.

10. An article support member according to claim 9 , wherein an upper surface of said protrusion comprises a cut-out region.

11. An article support member according to claim 8 , wherein said trimmed section is a local depression in a side wall of a protrusion.

12. An article support member according to claim 8 , wherein said trimmed section is a section that extends along a side of a top surface of a protrusion.

13. An article support member according to claim 8 , wherein said trimmed section comprises a carved section obtained by cutting, milling or drilling.

14. An article support member according to claim 8 , wherein said article support member is a support configured to support a patterning device, which serves to impart a beam with a pattern in its cross-section.

15. An article support member according to claim 8 , wherein said article support member is a substrate table configured to support a substrate to be patterned by a patterned beam onto a target portion of the substrate.

16. A method of manufacturing an article support member configured to support an article to be placed in a beam path of a projection beam of radiation on the article support member in a lithographic apparatus comprising:

providing the article support member including a clamp configured to provide a clamping pressure for clamping the article against the article support member;

evaluating a flatness of the article support member; and

trimming at least one section of the article support member so as to locally adjust a clamping pressure of the clamp.

17. A method according to claim 16 , wherein the trimming is performed iteratively.