Lithographic apparatus and device manufacturing method

• US 20070002300A1
• Filed: 05/18/2006
• Published: 01/04/2007
• Est. Priority Date: 05/16/2005
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV), CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Singer, Wolfgang, Flagello, Donis, Blahnik, Vladan, Geh, Bernd, Hansen, Steven
• Granted Patent: US 7,684,013 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70091 Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
• CPC Class Codes: G03F 7/70108 Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides
• CPC Class Codes: G03F 7/7025 Size or form of projection system aperture, e.g. aperture stops, diaphragms or pupil obscuration; Control thereof
• CPC Class Codes: G03F 7/70325 Resolution enhancement techniques not otherwise provided for, e.g. darkfield imaging, interfering beams, spatial frequency multiplication, nearfield lenses or solid immersion lenses

Abstract

A lithographic apparatus includes an illumination unit including a radiation source configured to generate a radiation bundle, an illumination optics with a numerical aperture NA₀ and an aperture system; a projection lens having a first numerical aperture NA_OB1; a support arranged between the illumination unit and the projection lens and configured to support a patterning device; a substrate support configured to support a substrate on which structures on the patterning device are imaged, wherein the first numerical aperture NA_OB1 of the projection lens is smaller than the numerical aperture NA₀ of the illumination unit.

Claims

1. A microlithographic projection apparatus comprising:

an illumination unit with at least one light source for generating a light bundle, with an illumination optics with a numerical aperture NA₀ and an aperture system, the apparatus comprising

a projection lens with at least a first numerical aperture NA_OB1,

a mask arranged between the illumination unit and the projection lens,

a substrate to which structures on the mask are imaged, wherein

the at least one first numerical aperture NA_OB1 of the projection lens is less than the numerical aperture NA₀ of the illumination unit.

2. The microlithographic projection apparatus of claim 1, wherein the projection lens has a second numerical aperture NA_OB2 greater than the numerical aperture NA₀ of the illumination unit.

3. The microlithographic projection apparatus of claim 1 or 2, wherein the numerical aperture NA₀ of the illumination unit is 1.5-fold in value up to 3-fold in value compared with the value of the first numerical aperture NA_OB1 of the projection lens.

4. The microlithographic projection apparatus of claim 1 or 2, wherein the mask can be illuminated from at least two direction α

₁ and α

₂ relative to an optical axis of the microlithographic projection apparatus, wherein sin α

₁ and sin α

₂ is the respective sinus between the optical axis and the respective direction of illumination, and wherein sin α

1>

NA₀ and/or sin α

₂<

NA₀.

6. Method for improving the resolution of a microlithographic projection apparatus according to claim 1, wherein an illumination setting with dark field components is matched to the illuminated structures during the illumination of the mask for imaging the structures of the mask on a substrate.

7. Method for improving the resolution of a microlithographic projection apparatus according to claim 2, wherein an illumination setting with dark field components is matched to the illuminated structures during the illumination of the mask for imaging the structures of the mask on a substrate.

8. Method of claim 6, wherein for a certain structure of the mask the dark field components are determined to inflate the image intensity of the conventional bright field component.

9. Method of claim 6, wherein in the interference pattern of the n-th and (n+1)-th diffraction order of the bright field an interference pattern of the (n+1)-th and (n+2)-th diffraction order of the dark field is superimposed.

10. Method of claim 6, wherein phase structures and normal structures are imaged, and wherein for the imaging of the phase structures dark field components are applied, and for the imaging of the normal structures bright field components are applied.

11. Method according to claim 6, wherein the bright field and dark field components of the illumination unit are determined by computer-assisted optimization.

12. Computer program for optimization of the dark field and bright field components in a microlithographic projection apparatus according to claim 1 or 2.

5. An illumination unit of a microlithographic projection apparatus with a projection lens, with at least a first numerical aperture NA_OB1, wherein the numerical aperture NA₀ of the illumination unit is greater than the at least one first numerical aperture NA_OB1 of the projection lens.

13. Method for the imaging of semiconductor structures on a photosensitive substrate, using a mask, a projection lens with an object-sided numerical aperture and an illumination system, the illumination system providing an illumination setting, the imaging comprising first image parts generated by interference of diffraction orders which comprise the 0-th diffraction order, the imaging also comprising second image parts generated by interference of diffraction orders without the 0-th diffraction order, wherein the first and the second image parts are superimposed during the imaging.

14. The method according to claim 13, wherein the illumination setting comprises first and second illumination components, wherein the first illumination component is exclusively formed by illumination directions with angles less than the object-sided numerical aperture of the projection lens, and wherein the second illumination component is exclusively formed by illumination directions with angles greater than the object-sided numerical aperture of the projection lens.

15. The method according to claim 13, wherein the mask comprises a first and a second structure F1 and F2, wherein these structures are different from each other by alignment, periodicity or shape.

16. The method according to claim 14, wherein the mask comprises a first and a second structure F1 and F2, wherein these structures are different from each other by alignment, periodicity or shape.

17. The method according to claim 15 or 16, wherein at least one of the two structures comprise phase structures.

18. The method according to claim 16, wherein the second illumination component images essentially only image parts of the second structure F2 on the photosensitive substrate.

19. Method for determining the illumination setting used in claims 13 or 14.

20. Projection exposure apparatus for the imaging of semiconductor structures on a photosensitive substrate, comprising a mask, a projection lens with an object-sided numerical aperture and an illumination system providing an illumination setting, wherein first image parts generated by interference of diffraction orders which comprise the 0-th diffraction order, and second image parts generated by interference of diffraction orders without the 0-th diffraction order are superimposed on the photosensitive substrate.

21. A lithographic apparatus comprising:

an illumination unit configured to condition a radiation beam and including a illumination optics, the illumination unit having a numerical aperture NA₀;

a support configured to support a patterning device, the patterning device configured to pattern the radiation beam to form a patterned radiation beam;

a substrate support configured to support a substrate; and

a projection lens having a first numerical aperture NA_OB1 and configured to project the patterned radiation beam onto the substrate, the first numerical aperture NA_OB1 of the projection lens being smaller than the numerical aperture NA₀ of the illumination unit.

22. The apparatus of claim 21, wherein the projection lens includes a second numerical aperture NA_OB2 that is greater than the numerical aperture NA₀ of the illumination unit.

23. The apparatus of claim 21, wherein the patterning device is illuminated from at least two direction α

₁ and α

₂ relative to an optical axis of the lithographic apparatus, wherein sin α

₁ and sin α

₂ is the respective sinus between the optical axis and the respective direction of illumination, and wherein sin α

₁>

NA₀ and/or sin α

₂<

NA₀.

24. A method of improving a resolution of a lithographic apparatus according to claim 21, the method comprising:

configuring an illumination setting having a dark field component in relation with a pattern to be imaged onto the substrate;

illuminating the pattern of the patterning device with the illumination setting; and

projecting an image of the illuminated pattern onto the substrate.

25. The method of claim 24, further comprising superimposing an interference pattern of the n-th and (n+1)-th diffraction order of a bright field with an interference pattern of the (n+1)-th and (n+2)-th diffraction order of the dark field component.

26. A computer program for configuring dark field and bright field components in a lithographic apparatus according to claim 21, the computer program having machine executable instructions, the instructions being executable by a machine to perform a method of improving a resolution of the lithographic apparatus, the method comprising:

configuring an illumination setting having a dark field component in relation with a pattern to be imaged onto the substrate;

illuminating the pattern of the patterning device with the illumination setting; and

projecting an image of the illuminated pattern onto the substrate.

27. A method of imaging a pattern onto a substrate, using a patterning device, a projection lens having an object-side numerical aperture and an illumination system, the illumination system providing an illumination setting, the method comprising:

superimposing a first and a second image part of the pattern onto the substrate, the first image part generated by interference of diffraction orders that include a 0-th diffraction order, the second image part generated by interference of diffraction orders without the 0-th diffraction order.

28. The method of claim 27, wherein the patterning device comprises a first and a second structure wherein the first and the second structure differ from each other in alignment, periodicity or shape.