System and method for compensating for thermal expansion of lithography apparatus or substrate

• US 20070075315A1
• Filed: 10/25/2005
• Published: 04/05/2007
• Est. Priority Date: 10/04/2005
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Baselmans, Johannes, Venema, Willem
• Granted Patent: US 7,391,503 B2
• Time in Patent Office: Days
• US Class Current: 257/72
• CPC Class Codes: G03F 7/70275 Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: G03F 7/70791 Large workpieces, e.g. glass substrates for flat panel displays or solar panels
• CPC Class Codes: G03F 7/70875 Temperature, e.g. temperature control of masks or workpieces via control of stage temperature
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters

Abstract

To prevent a substrate from expanding significantly to generate overlay errors an exposure operation takes place in two parts. A first part exposes boundary areas and a second part exposes the larger, bulk areas. In one example, a portion of the substrate is fixed and the substrate is exposed progressively from parts furthest from the fixed portions towards the fixed portion. In another example, a plurality of high velocity scans take place instead of a single slow scan, and the substrate is allowed to cool between the high velocity scans. In another example, a lithographic apparatus is heated in order to maintain a temperature differential between the apparatus and the surrounding environment, and to minimize any fluctuation due to the exposing radiation.

Claims

1. A device manufacturing method comprising:

exposing a feature on a substrate, the feature having a boundary, comprising,

performing a first exposure by projecting a modulated radiation beam onto the substrate to expose areas of the feature within a predetermined distance of the boundary, and

performing a second exposure by projecting the modulated beam of radiation onto the substrate to expose at least a part of the feature unexposed during the first exposure.

2. The method of claim 1, wherein substantially all the area of the feature unexposed in the first exposure is exposed in the second exposure.

3. The method of claim 1, wherein:

a plurality of the features are exposed on the substrate; and

during the first exposure areas within a predetermined distance of all the boundaries of the features within a region of the substrate are exposed by projecting the modulated radiation beam onto the substrate.

4. The method of claim 1, wherein the step of exposing the feature further comprises:

performing a third exposure by projecting the modulated beam of radiation onto the substrate to expose at least a part of the feature unexposed in the first exposure.

26. A flat panel display manufactured according to the method of any one of claims 1.

27. An integrated circuit device manufactured according to the method of claims 1.

5. A device manufacturing method, comprising:

fixing a portion of a substrate to a reference object to form a fixed portion of the substrate, the rest of the substrate remaining unfixed relative to the reference plate; and

exposing the substrate progressively in such a way that when any point on the substrate is exposed no point between it and a closest part of the fixed portion has been exposed during a current exposure sequence.

6. The method of claim 5, wherein the fixing a portion step comprises using at least one of the following geometries:

an external edge of the substrate and a line or point not coincident with an external edge of the substrate.

7. The method of claim 5, wherein during the exposing step the substrate is moved progressively to expose different target portions of the substrate, the target portions being exposed in a sequence such that when any target portion is exposed no portion of the substrate between it and the closest part of the fixed portion has been exposed.

8. A lithographic apparatus, comprising:

a projection system that projects a modulated radiation beam onto a target portion of a substrate;

a fixing device that fixes a portion of the substrate to a reference object; and

a controller configured to control the lithographic apparatus to expose the substrate progressively in such a way that when any point on the substrate is exposed no point between it and the closest part of the fixed portion has previously been exposed during a current exposure sequence.

9. The lithographic apparatus of claim 8, wherein the reference object is a substrate table that supports the substrate.

10. A device manufacturing method, comprising:

using a projection system to project a modulated beam of radiation onto a substrate; and

heating, during the projection, at least one of the projection system and the substrate to at least a predetermined temperature, the predetermined temperature being significantly above a temperature of a surrounding environment.

11. The method of claim 10, wherein the heating of at least one of the projection system and the substrate is temperature controlled in order to maintain a substantially constant temperature.

12. The method of claim 10, wherein both the projection system and the substrate are heated to the at least a predetermined temperature.

13. A lithographic apparatus, comprising:

a substrate table that supports a substrate;

a projection system that projects a patterned beam onto a target portion of the substrate; and

a heating system that heats at least one of the projection system and the substrate table.

14. The lithographic apparatus of claim 13, further comprising:

a thermometer that measures a temperature of at least one of the projection system and the substrate.

15. A device manufacturing method, comprising:

providing a substrate at least partially covered with a layer of radiation-sensitive material;

projecting a first modulated beam of radiation, having a first wavelength, onto a substrate;

projecting a second beam of radiation, having a second wavelength onto the substrate;

wherein the first wavelength is a wavelength at which the radiation-sensitive material is sensitive and the second wavelength is a wavelength at which the radiation-sensitive material is not sensitive.

16. The method of claim 15, wherein the second beam of radiation is modulated with a negative image of the first modulated beam of radiation.

17. A lithographic apparatus, comprising:

an illumination system that conditions a radiation beam;

a patterning system that modulates the radiation beam;

a substrate table that supports a substrate at least partially covered in a layer of radiation-sensitive material; and

a projection system that projects the modulated radiation beam onto a target portion of the substrate, wherein the illumination system conditions a radiation beam at first and second wavelengths, the first wavelength being a wavelength at which the radiation-sensitive material is sensitive and the second wavelength being a wavelength at which the radiation-sensitive material is not sensitive.

18. A device manufacturing method, comprising:

providing a substrate table that supports a substrate; and

projecting a beam of radiation onto the substrate using a projection system,

wherein at least one of the substrate table or a part of the projection system is coated in a material that has a transition between a state in which large amounts of heat are generated when an electromagnetic field is applied to the material and a state in which small amounts of heat are generated when the electromagnetic field is applied to the material.

19. The method of claim 18, wherein the material is a resistive material that has a positive temperature coefficient and a phase transition between a state of relatively low resistivity below a transition temperature and a state of relatively high resistivity above the transition temperature.

20. The method of claim 19, wherein the phase transition occurs due to at least one of the following:

a magnetic phase transition, a structural phase transition.

21. The method of claim 19, further comprising:

passing an electric current through the layer of resistive material to raise and hold its temperature just below the temperature at which the phase transition occurs,

wherein any further heating from the projection beam causing the temperature of the resistive material to increase above the phase transition and causes a reduction in the heating provided by the electric current.

22. The method according to claim 18, wherein the material undergoes a phase transition between a magnetically ordered state below a transition temperature and a magnetically less ordered state above the transition temperature.

23. The method of claim 22, further comprising:

applying a varying magnetic field to the material, which causes hysteretic heating in the material when the material is below the transition temperature.

24. The method of claim 22, wherein the magnetically ordered state is one of ferromagnetic and ferrimagnetic.

25. The method of claim 22, further comprising:

applying a varying magnetic field to the coating of material in order to cause hysteretic heating and raise and hold a temperature just below the temperature at which the transition occurs, any further heating from the projection beam causing the temperature of the coating of material to pass above the transition temperature and cause a reduction in the hysteretic heating.

28. A lithographic apparatus, comprising:

a substrate table constructed to support a substrate;

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

wherein at least one of the substrate table or a part of the projection system is coated in a material that has a transition between a state in which large amounts of heat are generated when an electromagnetic field is applied to the material and a state in which small amounts of heat are generated when an electromagnetic field is applied to the material.

29. The apparatus of claim 28, wherein the material is a resistive material that has a positive temperature coefficient and a phase transition between a state of relatively low resistivity below a transition temperature and a state of relatively high resistivity above the transition temperature.

30. The apparatus of claim 28, wherein the projection system comprises an array of lenses, the array of lenses being supported by a frame and the frame being coated in the resistive material.

31. The apparatus of claim 28, wherein the material undergoes a phase transition between a magnetically ordered state below a transition temperature and a magnetically less ordered state above the transition temperature.

32. The apparatus of claim 31, further comprising:

a magnetic source that provides a magnetic field to the material.

33. The apparatus of claim 31, wherein projection system comprises an array of lenses, the array of lenses being supported by a frame and the frame being coated in the resistive material.