Variable illumination source

• US 7,317,506 B2
• Filed: 03/29/2005
• Issued: 01/08/2008
• Est. Priority Date: 03/29/2005
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Socha, Robert John, Flagello, Donis George, Greeneich, James Sherwood
• Primary Examiner(s): Assouad; Patrick
• Assistant Examiner(s): Fenwick; Warren K
• Application Number:
  US11/091,927
• Publication Number:
  US 20070013888A1
• Time in Patent Office: 1,015 Days
• Field of Search: None
• US Class Current: 355/53
• CPC Class Codes: G03B 27/54 Lamp housings; Illuminating means
• 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]

Abstract

An apparatus and method for providing a variable illumination field for use in lithographic imaging for semiconductor manufacturing includes providing a an illumination system including a variable optical element having an array of addressable elements, each addressable element constructed and arranged to have a variable transmittance.

Claims

1. A lithographic projection apparatus comprising:

an illumination system configured to condition a radiation beam;

a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam;

a substrate table constructed to hold a substrate;

a projection system configured to project the patterned radiation beam onto a target portion of the substrate; and

a variable optical element forming a part of the illumination system and comprising an array of addressable elements, each addressable element constructed and arranged to have a variable transmittance.

2. An apparatus according to claim 1, further comprising a controller, configured and arranged to produce control signals for controlling the addressable elements of the variable optical element such that at a pupil plane of the patterning device, a selected illumination pattern is formed.

3. An apparatus according to claim 2, wherein the selected illumination pattern is selected based at least in part on the pattern of the patterned radiation beam.

4. An apparatus according to claim 1, wherein the addressable elements comprise picture elements of a liquid crystal display panel.

5. An apparatus according to claim 4, wherein the picture elements of the liquid crystal display panel have a first, on, state and a second, off state.

6. An apparatus according to claim 4, wherein the picture elements of the liquid crystal display panel have a plurality of states, wherein the transmittance of the picture elements varies between about 0 and about 1.

7. An apparatus according to claim 1, wherein each addressable element comprises a heterojunction having a band gap and wherein the transmittance of the heterojunction is variable by changing the band gap.

8. An apparatus according to claim 7, wherein the band gap is changeable by changing a voltage applied to the heterojunction.

9. An apparatus according to claim 8, wherein the changing a voltage comprises changing an amplitude of the voltage.

10. An apparatus according to claim 8, wherein the changing a voltage comprises reversing the voltage.

11. A method of imaging a pattern onto a substrate comprising:

producing a beam of radiation;

varying the transmittance of a plurality of addressable elements of a variable optical element;

impinging the beam of radiation on to the variable optical element thereby patterning the beam of radiation according to a desired illumination pattern;

after the patterning according to the desired illumination pattern, illuminating an image patterning device with the beam of radiation; and

after the illuminating, projecting the beam of radiation onto the substrate.

12. A method of imaging according to claim 11 wherein the variable optical element forms the desired illumination pattern at a pupil plane of the patterning device.

13. A method according to claim 11, wherein the addressable elements comprise picture elements of a liquid crystal display panel.

14. A method according to claim 11, further comprising selecting the desired illumination pattern based at least in part on a pattern of the image patterning device.

15. A method according to claim 13 wherein the varying the transmittance of the addressable elements further comprises switching the picture elements between an off state and an on state.

16. A method according to claim 13, wherein the varying the transmittance of the addressable elements further comprises varying the picture elements among a plurality of states between and including an off state and an on state.

17. A method according to claim 11, wherein the addressable elements comprise a heterojunction having a band gap and wherein the varying the transmittance of the addressable elements further comprises changing the band gap.

18. A method according to claim 17, wherein the changing the band gap further comprises changing a voltage applied to the band gap.

19. A method according to claim 18, wherein the changing the voltage comprises changing an amplitude of the voltage and/or reversing the voltage.

20. A semiconductor device manufactured according to the method of claim 12.