Lithographic apparatus and device manufacturing method

• US 20060007419A1
• Filed: 07/07/2004
• Published: 01/12/2006
• Est. Priority Date: 07/07/2004
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Baselmans, Johannes Jacobus Matheus, Mulkens, Johannes Catharinus Hubertus, Streefkerk, Bob, Mertens, Jeroen Johannes Sophia Maria, Hoogendam, Christiaan Alexander, Donders, Sjoerd Nicolaas Lambertus
• Granted Patent: US 7,463,330 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• 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 7/70866 of mask or workpiece
• CPC Class Codes: G03F 9/7026 Focusing
• CPC Class Codes: G03F 9/7034 Leveling

Abstract

In immersion lithography after exposure of a substrate is complete, a detector is used to detect any residual liquid remaining on the substrate and/or substrate table.

Claims

1. A lithographic projection apparatus comprising:

a substrate table configured to hold a substrate;

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

a liquid supply system configured to supply liquid to a space between the projection system and the substrate; and

a residual liquid detector configured to detect liquid remaining on the substrate and/or the substrate table after an exposure is completed.

2. The apparatus according to claim 1, further comprising a drying station configured to dry the substrate, the substrate table, or both in the event that liquid is detected by the residual liquid detector.

3. The apparatus according to claim 1, wherein the residual liquid detector comprises a level sensor configured to measure the position of a surface in a direction substantially parallel to an optical axis of the projection system, a tilt of a surface about axes substantially perpendicular to the optical axis of the projection system, or both.

4. The apparatus according to claim 3, wherein detection of liquid on the substrate, substrate table, or both is effected by the level sensor giving a measurement outside a normal operating range.

5. The apparatus according to claim 1, wherein the residual liquid detector comprises an alignment sensor configured to measure the position of a marker in a direction substantially perpendicular to an optical axis of the projection system.

6. The apparatus according to claim 5, wherein detection of liquid on the substrate, substrate table, or both is effected by the alignment sensor giving a measurement outside a normal operating range.

7. The apparatus according to claim 1, wherein the residual liquid detector comprises one or more devices selected from the group comprising an air gauge, a capacitive sensor, an automatically focusing spot projector, a scatterometer, a camera, an infrared sensor, and a grazing angle laser beam and a detector to detect scattered light.

8. The apparatus according to claim 1, wherein the residual liquid detector comprises a monitoring circuit configured to monitor a force applied by an actuator to maintain the substrate table at a constant vertical position.

9. The apparatus according to claim 1, wherein the projection system is provided at an exposure station and the residual liquid detector is provided at a measurement station, the measurement station being physically separate from the exposure station.

10. The apparatus according to claim 1, wherein the residual liquid detector is configured to generate, upon detection of residual liquid, an alarm or error signal to instruct performance of a drying action.

11. A device manufacturing method comprising projecting, using a projection system of a lithographic apparatus, a patterned beam of radiation through a liquid onto a substrate, the substrate being held by a substrate table, and, after the projecting is complete, detecting residual liquid on the substrate and/or the substrate table.

12. The method according to claim 11, further comprising drying the substrate, the substrate table, or both in the event that residual liquid is detected.

13. The method according to claim 11, wherein detecting residual liquid comprises measuring the position of a surface in a direction substantially parallel to an optical axis of the projection system, a tilt of a surface about axes substantially perpendicular to the optical axis of the projection system, or both.

14. The method according to claim 13, wherein detecting of residual liquid on the substrate, substrate table, or both is effected by the measuring of the position, tilt, or both giving a measurement outside a normal operating range.

15. The method according to claim 11, wherein detecting residual liquid comprises measuring the position of a marker in a direction substantially perpendicular to an optical axis of the projection system.

16. The method according to claim 15, wherein detecting of residual liquid on the substrate, substrate table, or both is effected by the measuring of the position giving a measurement outside a normal operating range.

17. The method according to claim 11, wherein detecting residual liquid is performed by one or more devices selected from the group comprising an air gauge, a capacitive sensor, an automatically focusing spot projector, a scatterometer, a camera, an infrared sensor, and a grazing angle laser beam and a detector to detect scattered light.

18. The method according to claim 11, wherein detecting residual liquid comprises monitoring a force applied by an actuator to maintain the substrate table at a constant vertical position.

19. The method according to claim 11, wherein projecting the patterned beam of radiation is performed at an exposure station and detecting residual liquid is performed at a measurement station, the measurement station being physically separate from the exposure station.

20. The method according to claim 11, wherein detecting residual liquid is performed in parallel with projecting the patterned beam.