Method and system for a maskless lithography rasterization technique based on global optimization

• US 20060209314A1
• Filed: 01/27/2006
• Published: 09/21/2006
• Est. Priority Date: 01/28/2005
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Latypov, Azat, Cebuhar, Wenceslao, Poultney, Sherman
• Granted Patent: US 7,469,058 B2
• Time in Patent Office: Days
• US Class Current: 358/1.100
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G03F 7/70508 Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus

Abstract

Provided are a method and system for determining states of spatial light modulator (SLM) pixels in a lithography system configured to print a desired pattern. The method includes determining diffraction orders associated with an ideal mask of a pattern to be printed by the lithography system, and then configuring the states of the SLM pixels to match all the diffraction orders that are relevant in the image formation.

Claims

1. A method for determining states of spatial light modulator (SLM) pixels in a lithography system configured to print a desired pattern, comprising:

determining diffraction orders associated with an ideal mask of a pattern to be printed by the lithography system; and

configuring the states of the SLM pixels to match determined diffraction orders related to the desired pattern.

2. The method of claim 1, wherein the diffraction orders are representative of characteristics associated with the SLM pixels.

3. The method of claim 1, wherein the pixel states are configured to substantially match the desired diffraction pattern.

4. The method of claim 3, wherein the match occurs within an extended projection optics (PO) of the lithography system.

5. The method of claim 4, wherein the determining includes a non-linear expression describing a pupil field within the PO.

6. The method of claim 4, wherein the determining includes linear graytone approximation.

7. The method of claim 6, wherein graytone approximation is a function of pixel state parameters.

8. The method of claim 1, wherein the configuring compensates for constraints associated with modulation characteristics of the SLM.

9. The method of claim 1, wherein the diffraction orders are a function of PO numerical aperture, coordinates of the extended pupil, and a illumination wavelength.

10. A method for performing optical rasterization of spatial light modulator (SLM) pixels in a lithography system as a function of a pupil of an ideal mask to rasterize and decompose a desired pattern, the method comprising:

generating pupil field diffraction orders corresponding to elementary objects associated with the desired pattern.

determining graytones for all of the SLM pixels to optimally approximate the generated diffraction orders within an essential pupil of the lithography system; and

selecting a state of each pixel to emulate a corresponding graytone assigned the pixel.

11. The method of claim 10, wherein the selecting includes (i) determining a complex valued distribution of the graytones and (ii) determining graytone matrix values to map the complex valued distribution of the graytones into the pupil field through the essential pupil.

12. The method of claim 10, wherein the elementary objects includes a union of polygons.

13. The method of claim 10, wherein the determining includes operation of complex-value techniques.

14. The method of claim 10, wherein the state include at least one from the group including tilt angle and voltage level.

15. An apparatus for determining states of spatial light modulator (SLM) pixels in a lithography system configured to print a desired pattern, comprising:

means for determining diffraction orders associated with an ideal mask of a pattern to be printed by the lithography system and

means for configuring the states of the SLM pixels to match determined diffraction orders related to the desired pattern.

16. The apparatus of claim 15, wherein the diffraction orders are representative of characteristics associated with the SLM pixels.

17. The apparatus of claim 15, wherein the pixel states are configured to substantially match the desired diffraction pattern.

18. The apparatus of claim 17, wherein the match occurs within an extended projection optics (PO) of the lithography system.

19. The apparatus of claim 18, wherein the determining includes a non-linear expression describing a pupil field within the PO.

20. The apparatus of claim 18, wherein the determining includes linear graytone approximation.

21. An apparatus for performing optical rasterization of spatial light modulator (SLM) pixels in a lithography system as a function of a pupil of an ideal mask to rasterize and decompose a desired pattern, the apparatus comprising:

means for generating pupil field diffraction orders corresponding to elementary objects associated with the desired pattern.

means for determining graytones for all of the SLM pixels to optimally approximate the generated diffraction orders within an essential pupil of the lithography system; and

means for selecting a state of each pixel to emulate a corresponding graytone assigned the pixel.

22. A computer readable medium carrying one or more sequences of one or more instructions for execution by one or more processors to perform a method for determining states of spatial light modulator (SLM) pixels in a lithography system configured to print a desired pattern, the instructions when executed by the one or more processors, cause the one or more processors to perform the steps of:

determining diffraction orders associated with an ideal mask of a pattern to be printed by the lithography system; and

configuring the states of the SLM pixels to match determined diffraction orders related to the desired pattern.