System and method for compensating for radiation induced thermal distortions

• US 20070076180A1
• 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: Tinnemans, Patricius, Venema, Willem, Maria Zaal, Koen
• Granted Patent: US 7,830,493 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• CPC Class Codes: G03F 7/70725 control
• CPC Class Codes: G03F 7/70875 Temperature, e.g. temperature control of masks or workpieces via control of stage temperature
• CPC Class Codes: G03F 7/70891 Temperature

Abstract

A system and method are used to compensate for thermal effect on a lithographic apparatus. The system comprises a patterning device, a projection system, a substrate position controller, and a substrate-position-based expansion-compensator. The patterning device modulates a radiation beam. The projection system projects the modulated radiation beam onto a target portion of a substrate. The substrate position controller moves the substrate relative to the projection system sequentially through a plurality of exposure positions. The substrate-position-based expansion-compensator interacts with the substrate position controller to modify the exposure positions in order at least partially to compensate for thermally-induced geometrical changes of at least one of the substrate and projection system.

Claims

1. A lithographic apparatus, comprising:

a patterning device that modulates a radiation beam;

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

a substrate position controller that moves the substrate relative to the projection system sequentially through a plurality of exposure positions; and

a substrate-position-based expansion-compensator that interacts with the substrate position controller to modify the exposure positions to at least partially compensate for thermally-induced geometrical changes of at least one of the substrate and the projection system.

2. The lithographic apparatus of claim 1, wherein the substrate-position-based expansion-controller modifies the exposure positions based on:

data associated with a temperature of at least one portion of at least one of the substrate and the projection system; and

data associated with an effect on the at least one of the substrate and the projection system caused by the temperature.

3. The lithographic apparatus of claim 1, wherein:

the substrate position controller moves the substrate in a direction substantially parallel to a first axis; and

the substrate-position-based expansion-compensator modifies the exposure positions in a direction parallel to the first axis.

4. The lithographic apparatus of claim 3, further comprising:

a data processing system configured to convert a first representation of a desired dose pattern into a control signal, the data processing system comprising a control-signal-based expansion-compensator that adapts the control signal to at least partially compensate for thermal expansion of at least one of the substrate and the projection system,

wherein the patterning device comprises an array of individually controllable elements, and

wherein the control signal controls the array of individually controllable elements.

5. The lithographic apparatus of claim 4, wherein the control-signal-based expansion-compensator adapts the control signal to at least partially compensate for thermal expansion of the substrate only in a direction perpendicular to the first axis.

6. The lithographic apparatus of claim 2, further comprising:

a substrate temperature measurement system that measures the temperature of at least a portion of the substrate,

wherein the substrate-position-based expansion controller modifies the exposure positions based on measurements from the temperature measurement system.

7. The lithographic apparatus of claim 6, further comprising:

a memory device that stores calibration data relating substrate temperature measurements to corresponding substrate geometries,

wherein the substrate-position-based expansion-compensator modifies the exposure positions based on measurements from the temperature measurement system and the calibration data.

8. The lithographic apparatus of claim 6, wherein

the substrate-position-based expansion-compensator modifies the exposure positions based on measurements from the temperature measurement system and an associated predictive model of the thermally-induced changes in substrate geometry.

9. The lithographic apparatus of claim 2, further comprising:

a projection system temperature measurement system that measures the temperature of at least a portion of the projection system,

wherein the substrate-position-based expansion-compensator modifies the exposure positions based on measurements from the temperature measurement system.

10. The lithographic apparatus of claim 9, further comprising:

a memory device that stores calibration data relating projection system temperature measurements to at least one of corresponding errors in imaging properties of the projection system and corresponding errors in the pattern formed on the substrate,

wherein the substrate-position-based expansion-compensator is modifies the exposure positions based on measurements from the temperature measurement system and the calibration data.

11. The lithographic apparatus of claim 9, wherein:

the substrate-position-based expansion-compensator modifies the exposure positions based on measurements from the temperature measurement system and an associated predictive model of at least one of the thermally-induced imaging error of the projection system and the error in the pattern formed on the substrate due to thermal effects in the projection system.

12. The lithographic apparatus of claim 2, wherein the substrate-position-based expansion-compensator modifies the exposure positions as a function of the desired dose pattern.

13. The lithographic apparatus of claim 12, wherein:

the substrate-position-based expansion-controller uses a predictive model of the thermally-induced geometrical changes in substrate geometry that uses the desired dose pattern as input.

14. The lithographic apparatus of claim 12, wherein the substrate-position-based expansion-compensator uses a predictive model of the thermally-induced imaging error of the projection system that uses the desired dose pattern as input.

15. The lithographic apparatus of claim 12, further comprising:

a memory device that stores calibration data relating dose pattern characteristics to corresponding changes in substrate geometry,

wherein the substrate-position-based expansion-compensator modifies the exposure positions based on an expected change in substrate geometry identified by reference to the calibration data and the desired dose pattern.

16. The lithographic apparatus of claim 12, further comprising:

a memory device that stores calibration data relating dose pattern characteristics to corresponding changes in the imaging properties of the projection system,

wherein the substrate-position-based expansion-compensator is modifies the exposure positions based on an expected change in the imaging properties of the projection system identified by reference to the calibration data and the desired dose pattern.

17. The lithographic apparatus of claim 1, further comprising:

a substrate distortion measuring device that measures thermally-induced changes in the geometry of the substrate,

wherein the substrate-position-based expansion-compensator is modifies the exposure positions on based on measurements from the distortion measuring device.

18. The lithographic apparatus of claim 17, wherein:

the substrate distortion measuring device measures at least one of the relative position and orientation of a plurality of markers formed on the surface of the substrate and compares results of these measurements with data representing the relative position, orientation, or both, of the plurality of markers expected for an undistorted substrate.

19. The lithographic apparatus of claim 1, further comprising:

a projection system imaging error determining device that detects changes in the imaging properties of the projection system.

20. The lithographic apparatus of claim 19, wherein:

the projection system imaging error determining device measures the relative positions of at least two elements of the projection system.

21. The lithographic apparatus of claim 19, wherein:

the projection system projecting at least one of a first modulated radiation beam predominantly of a first wavelength and a second modulated radiation beam predominantly of a second wavelength, different from the first wavelength;

a resist formed on the substrate undergoes a reaction when exposed to radiation of the first wavelength, but not when exposed to radiation of the second wavelength; and

the projection system imaging error determining device detects radiation of the second wavelength reflected from markers on the substrate to derive information about an imaging error of the projection system.

22. A method of producing a compensated dose pattern for lithography, comprising:

modeling an expected distortion to a pattern formed on a substrate by a radiation beam that has been modulated according to a desired dose pattern, the distortion arising due to thermal effects that the modulated radiation beam would have on a projection system during projection; and

calculating a compensated dose pattern to counteract the expected distortion.

23. The method of claim 22, further comprising:

modulating a radiation beam according to the compensated dose pattern; and

projecting the modulated radiation beam onto a substrate.

24. The method of claim 23, wherein:

the desired pattern to be formed on the substrate is defined relative to a plurality of reference points on the substrate; and

the modeling takes into account thermally-induced changes to the relative positions of the reference points.

25. The method of claim 23, wherein the compensated dose pattern is produced using interpolation between the reference points.

26. A method of producing a compensated dose pattern for lithography, comprising:

defining a desired pattern formed on a substrate relative to a plurality of reference points on the substrate;

modeling an expected distortion to a pattern formed on the substrate by a modulated radiation beam that has been modulated according to the desired pattern, the distortion arising due to thermal effects that the modulated radiation beam would have on the substrate when projected thereon; and

calculating a compensated dose pattern to counteract the expected distortion,

wherein the modeling takes into account thermally-induced changes to the relative positions of the reference points and the compensated radiation beam is produced by interpolation between the reference points.

27. The method of claim 26, further comprising:

modulating a radiation beam according to the compensated dose pattern; and

projecting the compensated radiation beam onto the substrate.

28-46. -46. (canceled)