Polarized radiation in lithographic apparatus and device manufacturing method
View Patent ↗A lithographic apparatus uses polarized light to improve the imaging properties such as exposure latitude, while maintaining and extending the lifetime of an illumination system in a lithographic apparatus.
1. A lithographic apparatus, comprising:
an illumination system configured to condition a radiation beam and to provide multiple poles, the poles configured to maximize the amount of diffracted radiation within a lens pupil and having, per pole, a choice of polarized radiation in either a first or a second direction to maximize the content of transverse electric polarization;
a support constructed to support a patterning device, the patterning device being configured to impart 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,
wherein the lithographic apparatus comprises an optical element, the optical element being configured to provide a first portion of the radiation beam with a linear polarization in the first direction, or to provide a first portion of the radiation beam with a linear polarization in the first direction and a second portion of the radiation beam with a linear polarization in the second direction, the second direction being perpendicular to the first direction.
2. A lithographic apparatus according to claim 1 , wherein the optical element is located between the radiation source and the illumination system.
3. A lithographic apparatus according to claim 1 , wherein the substrate table is movable in a scanning direction with respect to the patterning device, and the first direction of polarization is perpendicular or parallel to the scanning direction.
4. A lithographic apparatus according to claim 1 , wherein the illumination system is configured to provide segmented point-symmetric illumination modes and/or non-symmetric illumination modes.
5. A lithographic apparatus according to claim 1 , wherein the illumination system is configured to provide dipole, a-symmetric, quadrupole, and hexa-pole illumination.
6. A lithographic apparatus according to claim 1 , wherein the optical element comprises two half-wavelength plates.
7. A lithographic apparatus according to claim 1 , wherein at least 95% of the radiation beam is polarized into either the first or second directions.
8. A lithographic apparatus according to claim 2 , wherein the lithographic apparatus is provided with a further optical element located between an illuminator and the projection system, the further optical element being configured to change the polarization state of the first portion of the radiation beam into a polarization state different from the polarization state of the radiation beam before entering the optical element.
9. A lithographic apparatus according to claim 8 , wherein the further optical element comprises a half-wavelength plate.
10. A lithographic apparatus according to claim 8 , wherein the further optical element comprises a quarter-wavelength plate.
11. A lithographic apparatus according to claim 8 , wherein the further optical element comprises a depolarizer.
12. A lithographic apparatus according to claim 6 , wherein the half-wavelength plates are substantially triangular in shape.
13. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are in a condensor, an adjusting device or an integrator of the lithographic apparatus.
14. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are both placed in a condensor of the lithographic apparatus.
15. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are both placed in an adjusting device of the lithographic apparatus.
16. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are both placed in an integrator of the lithographic apparatus.
17. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are placed in or near a pupil plane of a condensor of the lithographic apparatus.
18. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are placed in or near the pupil plane of an adjusting device of the lithographic apparatus.
19. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are placed in or near the pupil plane of an integrator of the lithographic apparatus.
20. A lithographic apparatus according to claim 6 , wherein the two half-wavelength plates are formed from quartz silica.
21. A lithographic apparatus according to claim 1 , wherein a lifetime of the illumination system is at least about 30×10 9 shots.
22. A lithographic apparatus according to claim 1 , wherein the projection system has a numerical aperture greater than about 1.0.
23. A lithographic apparatus according to claim 1 , wherein at least part of the lithographic apparatus is immersed in an immersion fluid.
24. A lithographic apparatus according to claim 23 , wherein the immersion fluid is water.
25. A device manufacturing method, comprising:
providing a radiation beam with multiple poles, the poles configured to maximize the amount of diffracted radiation within a lens pupil;
providing a first portion of the radiation beam with a linear polarization in a first direction, or providing a first portion of the radiation beam with a linear polarization in a first direction and a second portion of the radiation beam with a linear polarization in a second direction, the second direction being substantially perpendicular to the first direction, and having, per pole, a choice of polarized radiation in either the first or the second direction to maximize the content of transverse electric polarization;
imparting a pattern to the radiation beam; and
projecting the patterned beam of radiation onto a target portion of a substrate.