Illumination system for illuminating a mask in a microlithographic exposure apparatus

• US 9,599,904 B2
• Filed: 03/07/2016
• Issued: 03/21/2017
• Est. Priority Date: 12/21/2007
• Status: Expired due to Fees

• Current Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Inventors: Schubert, Erich, Kohl, Alexander, Ziegler, Gerhard-Wilhelm, Patra, Michael, Deguenther, Markus, Layh, Michael
• Primary Examiner(s): NGUYEN, HUNG
• Application Number:
  US15/062,531
• Publication Number:
  US 20160187789A1
• Time in Patent Office: 379 Days
• Field of Search: 355/52, 355/53, 355/55, 355 67- 71
• US Class Current: 1/1
• CPC Class Codes: G03F 7/70083 Non-homogeneous intensity distribution in the mask plane
• CPC Class Codes: G03F 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• CPC Class Codes: G03F 7/70433 Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors

Abstract

An illumination system of a micro-lithographic projection exposure apparatus is provided, which is configured to illuminate a mask positioned in a mask plane. The system includes a pupil shaping optical subsystem and illuminator optics that illuminate a beam deflecting component. For determining a property of the beam deflecting component, an intensity distribution in a system pupil surface of the illumination system is determined. Then the property of the beam deflecting component is determined such that the intensity distribution produced by the pupil shaping subsystem in the system pupil surface approximates the intensity distribution determined before. At least one of the following aberrations are taken into account in this determination: (i) an aberration produced by the illuminator optics; (ii) an aberration produced by the pupil shaping optical subsystem; (iii) an aberration produced by an optical element arranged between the system pupil surface and the mask plane.

Claims

1. A method of operating an illumination system of a microlithographic projection exposure apparatus, the illumination system configured to illuminate a mask positioned in a mask plane, the illumination system comprising a beam deflecting component that produces an intensity distribution in a pupil surface, the illumination system also comprising a beam deflection array of reflective or transparent beam deflecting elements, each deflecting element configured to illuminate a spot in the pupil surface having a position that can be varied by changing a deflection angle produced by the beam deflecting element, the method comprising:

a) determining a target intensity distribution in the pupil surface of the illumination system;

b) determining an arrangement of spots in the pupil surface that approximates the target intensity distribution determined in a);

c) determining a function assigned to a beam deflecting element, the function describing a relationship between;

i) positions of the spot illuminated by the beam deflecting element in the pupil surface; and

ii) the deflection angle produced by the beam deflecting element when illuminating the light spots;

d) determining deflection angles to obtain the arrangement of spots determined in c) by using the function determined in c); and

e) supplying control signals to the beam deflecting elements such that the deflection angles determined in d) are produced.

2. The method of claim 1, wherein c) comprises determining the function via simulation.

3. The method of claim 1, wherein c) comprises taking into account an aberration produced by optical elements that illuminate the beam deflecting component and/or by optical elements arranged between the beam deflecting component and the system pupil surface.

4. The method of claim 1, wherein c) comprises determining the function via measurements.

5. The method of claim 1, wherein the functions are discrete or continuous functions.

6. The method of claim 1, wherein the same function is assigned to a plurality of beam deflecting elements.

7. The method of claim 1, wherein functions assigned to the beam deflecting elements are different.

8. The method of claim 1, wherein b) further comprises determining individually for each beam deflecting element a shape of the spot and/or an intensity distribution within the spot.

9. The method of claim 1, wherein b) further comprises determining individually for each beam deflecting element a shape of the spot on a position of the spot in the pupil surface and/or an intensity distribution within the spot on a position of the spot in the pupil surface.

10. The method of claim 8, wherein b) further comprises using simulation to determine individually for each beam deflecting element a shape of the spot and/or an intensity distribution within the spot.

11. The method of claim 8, wherein b) further comprises using measurement to determine individually for each beam deflecting element a shape of the spot and/or an intensity distribution within the spot.

12. The method of claim 1, wherein e) comprises supplying control signals to the beam deflecting elements in accordance with a feed-forward control scheme.

13. The method of claim 1, wherein e) comprises supplying control signals to the beam deflecting elements in accordance with a closed-loop control scheme to which the deflection angles determined in d) are supplied as target value.

14. The method of claim 1, wherein the beam deflecting component comprises a diffractive optical element.

15. The method of claim 14, wherein the deflection angles produced by the diffractive optical element are constant over a surface of the diffractive optical element.

16. The method of claim 14, wherein c) comprises taking into account an aberration produced by optical elements that illuminate the beam deflecting component and/or by optical elements arranged between the beam deflecting component and the system pupil surface.

17. The method of claim 16, wherein the aberration comprises on-linear properties of optical elements between the diffractive optical element and the system pupil surface.

18. The method of claim 17, wherein the aberration comprises violations of the sine condition.

19. The method of claim 14, wherein the intensity distribution determined in a) comprises a continuous region in which there is a non-zero intensity and which has a sub-region which:

i) has a total area which is at least 80% of the total an of the region; and

ii) in which a maximum variations of the intensity with respect to a mean intensity are less than 20%.

20. The method of claim 19, wherein the maximum variations of the intensity with respect to the mean intensity in the sub-region are less than 10%.