Lithographic apparatus, excimer laser and device manufacturing method

• US 20060146310A1
• Filed: 12/23/2005
• Published: 07/06/2006
• Est. Priority Date: 12/23/2004
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Buurman, Erik Petrus, De Klerk, Johannes Wilhelmus, Bruls, Richard Joseph, Castenmiller, Thomas Josephus Maria, De Kruif, Robertus Cornelis Martinus
• Granted Patent: US 7,595,863 B2
• Time in Patent Office: Days
• US Class Current: 355/69
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose
• CPC Class Codes: G03F 7/70575 Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength
• CPC Class Codes: G03F 7/70641 Focus

Abstract

A CD-pitch dependency for a lithographic pattern printing process is related to the spectral intensity distribution of radiation used for projecting the pattern. A CD-pitch dependency can vary from one system to another. This can result in an iso-dense bias mismatch between systems. The invention addresses this problem by providing a lithographic apparatus including an illumination system for providing a projection beam of radiation, a projection system for projecting a patterned beam onto a target portion of a substrate, and a substrate table for holding the substrate, with a controller to provide an adjustment of the spectral distribution of radiant intensity of the projection beam. The adjustment of the spectral intensity distribution is based on data relating to an iso dense bias, and comprises a broadening of the spectral bandwidth or a change of shape of the spectral intensity distribution.

Claims

1. A lithographic apparatus comprising:

a radiation system for conditioning a beam of electromagnetic radiation having a spectral distribution of radiant intensity;

a support structure for supporting a patterning device, the patterning device serving to impart the beam of radiation with a pattern in its cross-section;

a substrate table for holding a substrate;

a projection system for projecting the patterned beam of radiation onto a target portion of the substrate; and

a controller configured and arranged to provide an adjustment of said spectral distribution of radiant intensity based at least on data relating to exposure at a first focal position and exposure at a second focal position and representing a corresponding first printed size and second printed size of the feature.

2. A lithographic apparatus according to claim 1, wherein the spectral distribution of radiant intensity comprises a spectral intensity peak having a bandwidth and wherein said adjustment comprises a change of the bandwidth.

3. A lithographic apparatus according to claim 2, wherein the spectral distribution of radiant intensity is a superposition of a first and a second peaked spectral intensity distribution having a respective equal first and second bandwidth, and a respective equal first and second intensity, and a respective first and second peak wavelength, and wherein the adjustment comprises a change of difference between the first and second peak wavelength.

4. A lithographic apparatus according to claim 1, wherein the spectral distribution of radiant intensity comprises a spectral intensity peak having, with respect to a center wavelength, a symmetric shape and wherein said adjustment comprises a change of the symmetric shape into an asymmetric shape with respect to the center wavelength.

5. A lithographic apparatus according to claim 2, wherein the data represent a difference between the corresponding first printed size and second printed size of the feature.

6. A lithographic apparatus according to claim 5, wherein the data further comprise a target difference between the corresponding first printed size and second printed size of the feature.

7. A lithographic apparatus according to claim 6, wherein the adjustment of said spectral distribution of radiant intensity is arranged to match the difference to the target difference.

8. A lithographic apparatus according to claim 7, wherein the target difference is a difference between the corresponding first printed size and second printed size of the feature, as printed using the patterning device on a supplementary lithographic apparatus.

9. A lithographic according to any of the claims 1, wherein the radiation controller controls a source of the beam of radiation.

10. A lithographic apparatus according to claim 1, wherein the spectral distribution of radiant intensity is a superposition of a first and a second peaked spectral intensity distribution having a respective first and second bandwidth, first and second peak wavelength, and first and second intensity, and wherein said adjustment comprises a change of one or more of:

a difference between the first and second peak wavelength and difference between the first and second bandwidth,

a difference between the first and second peak wavelength and difference between the first and second intensity, and

a difference between the first and second peak wavelength and difference between the first and second bandwidth and difference between the first and second intensity.

11. A lithographic apparatus according to claim 10, wherein the difference between the first and second peak wavelength is selected from the group consisting of between 0 and 1 pm, and between 0 and 0.5 pm.

12. A lithographic apparatus according to claim 1, wherein the spectral distribution of radiant intensity comprises a spectral intensity peak having a bandwidth and wherein the radiation system comprises an excimer laser to provide the beam of radiation and having a bandwidth-controller arranged to control the bandwidth and whereby the bandwidth-controller is constructed and arranged to adjust one of the bandwidth, a peak wavelength of the spectral intensity distribution, a shape of the spectral intensity distribution, and the bandwidth and the peak wavelength, in reaction to a user supplied signal representative for a respective selected bandwidth, peak wavelength, shape, and bandwidth and peak wavelength of the spectral distribution.

13. A lithographic apparatus according to claim 12, whereby the signal representative for a selected bandwidth of the spectral distribution is provided by the controller.

14. An excimer laser having a bandwidth-controller arranged to control a bandwidth of the spectral distribution of radiant intensity, and whereby the bandwidth-controller is constructed and arranged to spectrally shift the bandwidth in reaction to a user supplied signal representative for a selected bandwidth shift of the spectral distribution.

15. A device manufacturing method comprising:

providing a beam of electromagnetic radiation having a spectral distribution of radiant intensity;

patterning the beam of radiation with a pattern in its cross-section using a patterning device;

projecting the patterned beam of radiation onto a target portion of a substrate; and

adjusting said spectral distribution of radiant intensity at least in part in accordance with data relating to exposure at a first focal position and exposure at a second focal position and representing a corresponding first printed size and second printed size of the feature.

16. A method according to claim 15, wherein the spectral distribution of radiant intensity comprises a spectral intensity peak having a bandwidth and wherein said adjusting comprises changing the bandwidth.

17. A method according to claim 15, wherein the spectral distribution of radiant intensity comprises a spectral intensity peak shaped symmetrically with respect to a center wavelength and wherein said adjusting comprises changing the spectral intensity peak into a spectral intensity peak shaped asymmetrically with respect to the center wavelength.

18. A method according to claim 16, wherein the data represent a difference between the corresponding first printed size and second printed size of the feature.

19. A method according to claim 18, wherein the data further comprise a target difference between the corresponding first printed size and second printed size of the feature.

20. A method according to claim 19, wherein the adjusting of said spectral distribution of radiant intensity comprises matching the difference to the target difference.

21. A method according to claim 20, wherein the target difference is a difference between the corresponding first printed size and second printed size of the feature, as printed using the patterning device on respectively a first lithographic apparatus and a second lithographic apparatus.

22. A method according to claim 15, wherein the adjusting is provided during one of a scanning exposure of a target portion on a substrate and a plurality of scanning exposures of a corresponding plurality of target portions on a substrate.

23. A microelectronic device manufactured according to the method of claim 15.

24. A lithographic apparatus comprising:

an illumination system for providing a beam of radiation;

a support structure for supporting a patterning device, the patterning device serving to impart the beam of radiation with a pattern in its cross-section;

a substrate table for holding a substrate;

a projection system for projecting the patterned beam of radiation onto a target portion of the substrate; and

a controller configured and arranged to change an energy spectrum of the beam of radiation such that the energy spectrum is asymmetric.

25. A lithographic apparatus as claimed in claim 24, wherein for a particular lithographic process to be performed on the lithographic apparatus, a process window is substantially symmetric with respect to focus.

26. A lithographic apparatus as claimed in claim 24, wherein the controller changes the energy spectrum by superimposition of at least two wavelength spectra with a wavelength difference and a bandwidth difference.

27. A lithographic apparatus as claimed in claim 26, wherein the wavelength difference is selected from the group consisting of between 0 and 4 pm, and between 0 and 1 pm, and the bandwidth difference (E95) selected from the group consisting of between 0 and 1.0 pm, and approximately 0.5 pm.

28. A lithographic apparatus as claimed in claim 26, wherein the at least two wavelength spectra further have different intensities.

29. A lithographic apparatus as claimed in claim 28, wherein the intensities differ by more than 10%.

30. A lithographic apparatus as claimed in claim 28, wherein

$1.1\le$



I left 



I right 

⁢

or ⁢

 

⁢

 

⁢

0.9 ≥



I left 



I right 

, where I_left is an intensity of a first wavelength spectra, and I_right is an intensity of a second wavelength spectra.

31. A lithographic apparatus as claimed in claim 24, further comprising:

a beamsplitter constructed and arranged to split the beam into at least two components having different wavelengths;

an optical component selected from the group consisting of a wavelength shifter constructed and arranged to shift an energy spectrum of at least one of the components, and an attenuator constructed and arranged to attenuate at least one of the components; and

a beam recombinator constructed and arranged to recombine the components.

32. A lithographic apparatus as claimed in claim 24, comprising a plurality of radiation sources.

33. A lithographic apparatus as claimed in claim 32, wherein the radiation sources have discrete and separate output peaks.

34. A lithographic apparatus as claimed in claim 33, wherein the separation of the discrete peaks is selected from the group consisting of between 0 and 1.0 pm and between 0 and 0.5 pm.

35. A lithographic apparatus as claimed in claim 24, wherein the asymmetric energy spectrum comprises at least two wavelength spectra which are exposed upon the substrate substantially simultaneously.

36. A lithographic apparatus as claimed in claim 24, wherein the asymmetric energy spectrum comprises at least two wavelength spectra which are exposed upon the substrate sequentially.

37. A device manufacturing method comprising:

patterning a beam of radiation with a pattern in its cross-section;

projecting the patterned beam of radiation onto a target portion of a substrate; and

controlling an energy spectrum of the beam of radiation to be asymmetric.

38. A device manufacturing method as claimed in claim 37, wherein the energy spectrum is made asymmetric within an illumination system of a lithographic apparatus used in the method.

39. A device manufacturing method as claimed in claim 37, wherein the energy spectrum is made asymmetric at a source of the radiation.

40. A device manufacturing method as claimed in claim 37, wherein the controlling further comprises:

splitting the beam into at least two components having different wavelengths;

shifting an energy spectrum of one of the components;

attenuating the shifted component; and

recombining the components to re-form the beam.

41. A device manufacturing method as claimed in claim 37, wherein the controlling further comprises controlling optical components of an illumination system of a lithography system used in the method.

42. A microelectronic device manufactured according to the method of claim 37.