Projection exposure apparatus, cleaning and maintenance methods of a projection exposure apparatus, and device manufacturing method

• US 20110170080A1
• Filed: 03/21/2011
• Published: 07/14/2011
• Est. Priority Date: 09/26/2003
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tani, Yasuhisa, Shiozawa, Masaki
• Granted Patent: US 8,724,076 B2
• Time in Patent Office: Days
• US Class Current: 355/30
• CPC Class Codes: B08B 3/10 with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration
• CPC Class Codes: G03F 7/2041 in the presence of a fluid, e.g. immersion; using fluid cooling means
• 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 7/70916 Pollution mitigation, i.e. mitigating effect of contamination or debris, e.g. foil traps
• CPC Class Codes: G03F 7/70925 Cleaning, i.e. actively freeing apparatus from pollutants, e.g. using plasma cleaning
• CPC Class Codes: G03F 7/70975 Assembly, maintenance, transport or storage of apparatus

Abstract

A projection exposure apparatus that exposes a substrate with a liquid interposed between a surface of the substrate and an optical element on the substrate side of a projection optical system; includes liquid supply and discharge mechanisms, which supply the liquid via a liquid supply tube as they recover the liquid via a liquid recovery tube, and an adhesion preventing mechanism that prevents an adhesion of impurities on member forming a flow path for the liquid.

Claims

1. A liquid immersion type projection exposure apparatus in which a gap between an optical element and an object of exposure is filled with a liquid and the object is exposed, the liquid immersion type projection exposure apparatus comprising:

a liquid supply system which supplies the liquid to the gap; and

cleaning means for removing adhering substances within a flow path of the liquid, the flow path being separate from the gap and supplying the liquid to the gap.

2. A projection exposure apparatus according to claim 1, wherein the cleaning means has a supply flow volume ascertainment unit, which ascertains a liquid supply flow volume per unit time, and a flow volume fluctuation control unit which causes the liquid supply flow volume per unit time to fluctuate.

3. A projection exposure apparatus according to claim 2, further comprising a liquid recovery system which recovers the liquid, wherein

the cleaning means has a recovery flow volume ascertainment unit, which ascertains a liquid recovery flow volume per unit time, and

the flow volume fluctuation control unit controls the liquid supply system and the liquid recovery system so that the liquid supply flow volume per unit time and the liquid recovery flow volume per unit time become linked and fluctuate.

4. A projection exposure apparatus according to claim 2, wherein the liquid supply flow volume per unit time fluctuates at an amplitude of 0.1% or more with respect to a time average value of the liquid supply flow volume.

5. A projection exposure apparatus according to claim 1, wherein the cleaning means removes the adhering substances from inside of the flow path by mixing one or more bubbles of a volume of 1 ml or less into the liquid.

6. A projection exposure apparatus according to claim 1, wherein the cleaning means operates to remove the adhering substances from the inside of the flow path when exposure has stopped.

7. A projection exposure apparatus according to claim 1, wherein the optical element is a synthetic calcium fluoride monocrystal.

8. A projection exposure apparatus according to claim 7, wherein a surface of the optical element that contacts the liquid is coated with magnesium fluoride.

9. A projection exposure apparatus according to claim 1, wherein purified water or an aqueous solution in which salts are dissolved is used as the liquid.

29. A device manufacturing method that uses a liquid immersion type projection exposure apparatus as recited in claim 1.

30. A device manufacturing method that uses a projection exposure apparatus as recited in claim 3.

10. A cleaning method of a liquid immersion type projection exposure apparatus in which a gap between an optical element and an object of exposure is filled with a liquid and the object is exposed, the method comprising:

causing, when supplying the liquid, a liquid supply volume and a liquid recovery flow volume to fluctuate to remove adhering substances in a flow path of the liquid.

11. A cleaning method of the projection exposure apparatus according to claim 10, wherein the adhering substances in the flow path are removed by causing fluctuation at an amplitude of 0.1% or more for the liquid supply volume per unit time with respect to a time average value of the liquid supply flow volume.

27. A device manufacturing method that uses the cleaning method of a liquid immersion type projection exposure apparatus as recited in claim 10.

12. A cleaning method of a liquid immersion type projection exposure apparatus in which a gap between an optical element and an object of exposure is filled with a liquid, the method comprising:

mixing, when supplying the liquid, one or more bubbles of a volume of 1 ml or less into the liquid to clean an inside of a flow path of the liquid.

28. A device manufacturing method that uses the cleaning method of a liquid immersion type projection exposure apparatus as recited in claim 12.

13. A liquid immersion type projection exposure apparatus that fills a space between a first object and a second object with a liquid and irradiates exposure light onto an object of exposure via the liquid, the liquid immersion type projection exposure apparatus comprising:

a liquid supply system which supplies the liquid to the space;

a liquid recovery system which recovers the liquid from the space; and

a cleaning device that cleans a flow path of the liquid, the flow path being separate from the space and discharging the liquid from the space.

14. A projection exposure apparatus according to claim 13, wherein the first object includes an optical element, and the exposure light is irradiated onto the object of exposure via the optical element and the liquid.

15. A projection exposure apparatus according to claim 13, wherein the second object is the object of exposure.

16. A projection exposure apparatus according to claim 13, wherein the flow path includes a liquid supply flow path for supplying the liquid.

17. A projection exposure apparatus according to claim 13, wherein the flow path includes a liquid recovery flow path for recovering the liquid.

18. A projection exposure apparatus according to claim 13, wherein the cleaning device removes impurities within the flow path.

19. A projection exposure apparatus according to claim 13, wherein the cleaning device performs cleaning of the flow path by causing the liquid flow volume within the flow path to fluctuate.

20. A projection exposure apparatus according to claim 13, wherein the cleaning device performs cleaning of the flow path by causing a liquid into which bubbles have been mixed to flow in the flow path.

21. A projection exposure apparatus according to claim 13, wherein the cleaning device operates during a stoppage of exposure.

22. A projection exposure apparatus according to claim 13, wherein purified water or an aqueous solution in which salts are dissolved is used as the liquid.

31. A device manufacturing method that uses a liquid immersion type projection exposure apparatus as recited in claim 13.

23. A maintenance method of a liquid immersion type projection exposure apparatus in which a gap between a first object and a second object is filled with a liquid and an object of exposure is exposed, the method comprising:

cleaning a flow path of the liquid, when exposure of the object is not being performed, the flow path being separate from the gap and supplying the liquid to the gap or discharging the liquid from the gap.

24. A maintenance method according to claim 23, wherein the cleaning of the flow path is performed by causing a liquid flow volume within the flow path to fluctuate.

25. A maintenance method according to claim 23, wherein the cleaning is performed by causing a liquid into which bubbles have been mixed to flow within the flow path.

26. A device manufacturing method that uses the maintenance method of a projection exposure apparatus as recited in claim 23.