Substrate distortion measurement

• US 20070008531A1
• Filed: 07/06/2005
• Published: 01/11/2007
• Est. Priority Date: 07/06/2005
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Smeets, Erik
• Granted Patent: US 8,139,218 B2
• Time in Patent Office: Days
• US Class Current: 356/401
• CPC Class Codes: G03F 7/70716 Stages
• CPC Class Codes: G03F 7/70783 Handling stress or warp of chucks, masks or workpieces, e.g. to compensate for imaging errors or considerations related to warpage of masks or workpieces due to their own weight
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load

Abstract

A substrate distortion measurement apparatus comprising one or more optical detectors arranged to measure the locations of pits or holes provided in a substrate, a memory arranged to store previously determined locations of the pits or holes in the substrate, and a comparator arranged to compare the measured locations of the pits or holes with the previously determined locations of the pits or holes, to determine distortion of the substrate.

Claims

1. A method comprising:

(i) measuring the locations of marks on a substrate;

(ii) comparing the measured locations with previously determined locations of the marks to determine distortions in the substrate;

(iii) exposing the substrate to patterned radiation.

2. The method of claim 1, wherein said marks include pits.

3. The method of claim 2, wherein said pits have a width in the range of 100-1000 nm.

4. The method of claim 1, wherein distortions in an area of the substrate are determined prior to exposing the area of the substrate.

5. The method of claim 4, wherein said marks face away from said area of the substrate.

6. The method of claim 4, wherein said patterned radiation is provided using a contrast device.

7. The method of claim 6, further comprising adjusting a pattern of the contrast device relative to the determined distortions in said area of the substrate prior to exposing the area of the substrate to radiation.

8. The method of claim 1, wherein said substrate comprises a plastic layer.

9. The method of claim 1, wherein said substrate comprises a glass layer.

10. The method of claim 1, wherein said measuring the locations of marks on a substrate is effected using a laser.

11. The method of claim 10, wherein the marks are provided in a layer of the substrate which is opaque and reflective to light at a wavelength used to measure the locations of the pits, and one or more other layers of the substrate are substantially transparent to the wavelength.

12. The method of claim 1, further comprising measuring the size of the marks.

13. An article obtained by the method of claim 1.

14. A substrate comprising

a photosensitive layer;

and

a mark layer having at least 1000 marks.

15. The substrate of claim 14, wherein said photosensitive layer is a resist layer.

16. The substrate of claim 14, wherein said marks face away from said photosensitive layer.

17. The substrate of claim 14, wherein said substrate comprises a plastic layer.

18. The substrate of claim 14, wherein said substrate is a polygonal substrate.

19. The substrate of claim 18, wherein at least one side of side polygonal substrate has a length of at least 50 cm.

20. The substrate of claim 14, wherein said mark layer comprises at least 1000000 marks.

21. The substrate of claim 14, wherein said marks include pits.

22. The substrate of claim 14, wherein said marks are arranged in rows.

23. A substrate distortion measurement apparatus comprising:

(i) a detector arranged to measure locations of marks provided on a substrate,

(ii) a memory arranged to store previously measured locations of the marks that are located on the substrate, and

(iii) a comparator arranged to compare the measured locations of the marks with the previously measured locations of the marks.

24. An apparatus according to claim 23, wherein one or more optical sources are arranged to direct light onto the substrate such that the light is reflected from the substrate towards the one or more optical detectors, the light being modulated by the marks in the substrate.

25. An apparatus according to claim 23, wherein each of the one or more optical sources is mounted on a servo and is arranged to track marks on the substrate.

26. An apparatus according to claim 25, wherein the servo is arranged to provide an output which indicates movement of the servo when tracking the row of pits on the substrate.

27. An apparatus according to claim 26, wherein the output of the servo is connected to the comparator.

28. An apparatus according to claim 24, wherein an output from each optical detector is connected to the comparator.

29. A lithography apparatus comprising the apparatus of claim 23.

30. The lithography apparatus of claim 29, further comprising an array of moveable mirrors arranged to form a pattern to be projected onto the substrate, and control electronics arranged to adjust the pattern formed by the moveable mirrors to compensate for the determined distortion of the substrate.