Lithographic apparatus and device manufacturing method

• US 20050259236A1
• Filed: 09/22/2004
• Published: 11/24/2005
• Est. Priority Date: 09/29/2003
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Straaijer, Alexander
• Granted Patent: US 7,158,211 B2
• Time in Patent Office: Days
• US Class Current: 355/72
• CPC Class Codes: G03F 7/70341 Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply chemical composition of immersion liquids G03F7/2041
• CPC Class Codes: G03F 7/707 Chucks, e.g. chucking or un-chucking operations or structural details

Abstract

A table configured to support a substrate has one or more projections which support the substrate. In an embodiment, the table also has a raised perimeter defining a space which is configured to be filled with a liquid. A pump is configured to remove liquid from the space via outlet passages to an optional inlet. The removal of liquid can create a pressure differential across the substrate which then clamps it in place. Liquid circulated to the inlet may be filtered by a filter to remove contaminants.

Claims

1. A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, comprising:

a table having a clamping surface, the clamping surface having one or more projections configured to support the substrate when clamped thereto; and

a pump configured to pump a liquid through a space between the clamping surface and the substrate, so that when liquid is pumped through the space, the liquid in the space is at a lower pressure that a fluid on an other side of the substrate such that a net force is exerted on the substrate to hold it on the clamping surface.

2. The apparatus according to claim 1, wherein the table has a passage within it, the passage having an opening on the clamping surface, and wherein the pump is configured to pump liquid through the passage to create a pressure differential across the substrate.

3. The apparatus according to claim 1, further comprising a filter configured to filter the liquid.

4. The apparatus according to claim 1, wherein the pump is configured to pump the liquid into a reservoir to supply the space so as to form a closed liquid circuit.

5. The apparatus according to claim 1, further comprising a controller configured to reverse the direction that the pump pumps the liquid.

6. The apparatus according to claim 1, comprising a liquid supply system configured to fill a space between a projection system used to transfer the pattern and the substrate with a liquid.

7. The apparatus according to claim 6, wherein the liquid supply system is configured to supply the liquid to only a localized area on the substrate.

8. The apparatus according to claim 1, comprising a raised perimeter configured to contain a level of the liquid sufficient to immerse a final element of a projection system used to transfer the pattern.

9. The apparatus according to claim 1, comprising a raised perimeter and an inlet to supply liquid to the space, both configured to keep a level of the liquid sufficient to cover only a lower surface of the substrate.

10. The apparatus according to claim 1, wherein the table has a plurality of projections and a plurality of passages between the projections and the pump is configured to pump liquid through the passages.

11. The apparatus according to claim 10, wherein the projections and passages are arranged to form a substantially evenly distributed pressure differential across the substrate.

12. A device manufacturing method comprising transferring a pattern from a patterning device onto a substrate, wherein the substrate is held on a clamping surface of a table by providing a liquid in the space between the substrate and the clamping surface that is at a lower pressure than a fluid on an other side of the substrate.

13. The method according to claim 12, comprising pumping the liquid through a passage in the table, the passage having an opening on the clamping surface, so as to create a pressure differential across the substrate.

14. The method according to claim 12, further comprising filtering the liquid to remove contaminants.

15. The method according to claim 12, comprising pumping the liquid into a reservoir to supply the space so as to form a closed liquid circuit.

16. The method according to claim 12, further comprising reversing the direction that the pump pumps the liquid.

17. The method according to claim 12, comprising filling a space between a projection system used to transfer the pattern and the substrate with a liquid.

18. The method according to claim 17, comprising supplying the liquid to only a localized area on the substrate.

19. The method according to claim 12, comprising maintaining a level of the liquid sufficient to immerse a final element of a projection system used to transfer the pattern.

20. The method according to claim 12, comprising maintaining a level of the liquid sufficient to cover only a lower surface of the substrate.

21. The method according to claim 12, wherein the table has a plurality of projections and a plurality of passages between the projections and comprising pumping the liquid through the passages.

22. The method according to claim 21, wherein the projections and passages arranged to form a substantially evenly distributed pressure differential across the substrate.