Lithographic apparatus and device manufacturing method

• US 8,363,208 B2
• Filed: 02/04/2010
• Issued: 01/29/2013
• Est. Priority Date: 06/11/2003
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: De Smit, Joannes Theodoor, Banine, Vadim Yevgenyevich, Bisschops, Theodorus Hubertus Josephus, Modderman, Theodorus Marinus, Dierichs, Marcel Mathijs Theodore Marie
• Primary Examiner(s): Artman, Thomas R
• Application Number:
  US12/700,602
• Publication Number:
  US 20100128235A1
• Time in Patent Office: 1,090 Days
• Field of Search: 355/30, 355/50, 355/52, 355/53, 355/67, 355/72, 355/77
• US Class Current: 355/30
• 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 7/708 Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
• CPC Class Codes: G03F 7/70858 Environment aspects, e.g. pressure of beam-path gas, temperature pollution aspects G03F7/70916

Abstract

A lithographic apparatus and device manufacturing method makes use of a liquid confined in a reservoir between the projection system and the substrate. Bubbles forming in the liquid from dissolved atmospheric gases or from out-gassing from apparatus elements exposed to the liquid are detected and/or removed so that they do not interfere with exposure and lead to printing defects on the substrate. Detection may be carried out by measuring the frequency dependence of ultrasonic attenuation in the liquid and bubble removal may be implemented by degassing and pressurizing the liquid, isolating the liquid from the atmosphere, using liquids of low surface tension, providing a continuous flow of liquid through the imaging field, and/or phase shifting ultrasonic standing-wave node patterns.

Claims

1. A lithographic projection apparatus comprising:

a support structure configured to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern in its cross-section;

a substrate table configured to hold a substrate;

a projection system arranged to project the patterned radiation beam onto a target portion of the substrate;

a liquid supply system configured to at least partly fill a space between the projection system and the substrate table with a liquid; and

a cleaning device configured to dislodge bubbles or contaminants from the substrate, the substrate table, or both the substrate and substrate table.

2. An apparatus according to claim 1, wherein the cleaning device comprises an ultrasonic transducer.

3. An apparatus according to claim 1, further comprising a detector configured to detect bubbles or particles in liquid.

4. An apparatus according to claim 3, wherein at least part of the detector is located in a member configured to at least partly confine liquid in the space.

5. An apparatus according to claim 1, wherein the cleaning device is located in a member configured to at least partly confine liquid in the space.

6. An apparatus according to claim 5, wherein the cleaning device is mechanically isolated from, or at least in damped connection with, the member.

7. An apparatus according to claim 5, wherein the member is configured to at least partly confine liquid to substantially only cover an area on the substrate or substrate table less than the area of the whole substrate.

8. An apparatus according to claim 1, wherein the cleaning device is configured to couple directly to the liquid in the space.

9. An apparatus according to claim 1, configured to provide a continuous flow of liquid over the projection system and the substrate and/or substrate table in the space.

10. An apparatus according to claim 1, wherein the cleaning device is configured to be mechanically released from the projection system.

11. An apparatus according to claim 1, wherein the cleaning device is configured to dislodge bubbles or contaminants automatically.

12. An apparatus according to claim 11, wherein the cleaning device is configured to cycle on and off according to a rate of contamination.

13. A lithographic projection apparatus comprising:

a support structure configured to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern in its cross-section;

a substrate table configured to hold a substrate;

a projection system arranged to project the patterned radiation beam onto a target portion of the substrate;

a liquid supply system configured to at least partly fill a space between the projection system and the substrate table with a liquid;

a member configured to at least partly confine liquid in the space; and

a cleaning device, located in the member, configured to dislodge bubbles or contaminants.

14. An apparatus according to claim 13, wherein the cleaning device is configured to dislodge bubbles or contaminants from the projection system.

15. An apparatus according to claim 13, wherein the cleaning device comprises an ultrasonic transducer.

16. An apparatus according to claim 13, wherein the cleaning device is mechanically isolated from, or at least in damped connection with, the member.

17. An apparatus according to claim 13, wherein the cleaning device is configured to couple directly to liquid in the space.

18. An apparatus according to claim 13, wherein the member is configured to at least partly confine liquid to substantially only cover an area on the substrate or substrate table less than the area of the whole substrate.

19. An apparatus according to claim 13, configured to provide a continuous flow of liquid over the projection system and the substrate and/or substrate table in the space.