Substrate placement in immersion lithography

• US 20080106723A1
• Filed: 10/09/2007
• Published: 05/08/2008
• Est. Priority Date: 12/10/2004
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Nijmeijer, Gerrit, Cornelia Maria Van Eijck, Petrus Anton, Hoogendam, Christiaan, Cuperus, Minne
• Granted Patent: US 8,077,291 B2
• Time in Patent Office: Days
• US Class Current: 355/77
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01B 11/272 using photoelectric detection 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 7/707 Chucks, e.g. chucking or un-chucking operations or structural details
• CPC Class Codes: G03F 7/70716 Stages
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position
• CPC Class Codes: G03F 9/7011 Pre-exposure scan; original with original holder alignment; Prealignment, i.e. workpiece with workpiece holder

Abstract

A method for determining an offset between a center of a substrate and a center of a depression in a chuck includes providing a test substrate to the depression, the test substrate having a dimension smaller than a dimension of the depression, measuring a position of an alignment mark of the test substrate while in the depression, and determining the offset between the center of the substrate and the center of the depression from the position of the alignment mark.

Claims

1. A method for determining an offset between a center of a substrate and a center of a depression in a chuck, comprising:

providing a test substrate to the depression, the test substrate having a dimension smaller than a dimension of the depression;

measuring a position of an alignment mark of the test substrate while in the depression; and

determining the offset between the center of the substrate and the center of the depression from the position of the alignment mark.

2. The method according to claim 1, wherein providing the test substrate to the depression comprises loading the test substrate inside the depression using a substrate handler.

3. The method according to claim 1, wherein measuring the position of the alignment mark of the test substrate comprises measuring the position of the alignment mark relative to a reference mark of the chuck or vice versa.

4. The method according to claim 1, further comprising:

determining a position of the center of the depression relative to a position of a reference mark of the chuck or vice versa; and

determining a position of the center of the test substrate relative to the position of the alignment mark of the test substrate or vice versa.

5. The method according to claim 4, wherein measuring the position of the center of the test substrate is performed with a prealigner.

6. The method according to claim 1, wherein the dimension of the test substrate is such that, when the test substrate is in the depression, a gap between an edge of the test substrate and an edge of the depression is greater than a maximum offset.

7. The method according to claim 1, wherein measuring the position of the alignment mark of the test substrate is performed with an optical system.

8. The method according to claim 7, wherein the optical system comprises an interferometer and an optical alignment system.

9. The method according to claim 1, further comprising calibrating a substrate handler to take into account the offset.

10. The method according to claim 9, wherein calibrating the substrate handler includes shifting a positioning of substrates by the substrate handler to correct for the offset so that a subsequent substrate provided by the substrate handler to the depression is substantially centered inside the depression.

11. A method for determining an offset between a center of a substrate and a center of a depression in a chuck, comprising:

loading the substrate on a pin of the chuck and moving the substrate by translating the pin in a first direction until the substrate reaches an opening of the depression in the chuck;

determining to what extent the substrate should be translated in a plane substantially perpendicular to the first direction to allow the substrate to enter inside the depression without colliding with a surface of the chuck or an edge of the depression in the chuck; and

determining the offset of the substrate relative to the depression from determination of the translation in the plane.

12. The method according to claim 11, wherein determining to what extent the substrate should be translated comprises translating the substrate, in the plane on the pin relative to the chuck, translating the chuck, in the plane, relative to the substrate or the pin, or both, until a footprint of the substrate would fit into the depression.

13. The method according to claim 11, wherein loading the substrate on a pin of the chuck is performed with a substrate handler.

14. The method according to claim 11, further comprising calibrating the substrate handler to take into account the offset.

15. The method according to claim 14, wherein calibrating the substrate handler includes shifting positioning of substrates by of the substrate handler by an amount to correct for the offset so that a subsequently positioned substrate is substantially centered inside the depression.

16. The method according to claim 14, wherein calibrating the substrate handler includes correcting for substrate positioning so that the gap of a subsequently positioned substrate is equally wide inside the depression.