Lithographic apparatus and device manufacturing method
A liquid confinement system for use in immersion lithography is disclosed in which the meniscus of liquid between the liquid confinement system and the substrate is pinned substantially in place by a meniscus pinning feature. The meniscus pinning feature comprises a plurality of discrete outlets arranged in a polygonal shape.
1. A lithographic projection apparatus having a projection system to project a pattern from a patterning device onto a substrate, the apparatus comprising a liquid confinement structure to at least partly confine a liquid to a space between the projection system and the substrate, the liquid confinement structure comprising:
a plurality of outlets in a bottom surface of the liquid confinement structure, the plurality of outlets configured to remove liquid from the space and gas from outside the space to substantially pin a meniscus of the liquid in the space due to the creation of a gas flow, the outlets being distributed around the space such that the meniscus extends around the space, each outlet having a cross-sectional dimension of 0.2 mm or greater, and being, in plan, spaced apart from each other between 0.25 and 10 times their maximum plan dimension and two or more outlets of the plurality of the outlets not being at the bottom of a groove in the bottom surface.
2. The apparatus of claim 1 , wherein each of the outlets are attached to a separate suction source.
3. The apparatus of claim 1 , wherein each of the outlets is shaped such that two phase substantially annular flow exits through the outlets.
4. The apparatus of claim 1 , wherein a surface of the liquid confinement system comprises a step change in distance between 0.2 mm and 10.0 mm radially outwardly of the outlets, the surface, in use, facing the substrate and the step change in distance extending away from the outlets in a direction away from the substrate.
5. The apparatus of claim 1 , wherein each of the outlets is an outlet of an elongate passageway whose longitudinal axis is substantially perpendicular to the substrate.
6. The apparatus of claim 1 , wherein the outlets are positioned relative to each other to form, in plan, a polygonal shape.
7. The apparatus of claim 1 , further comprising a gas knife positioned radially outwardly of the outlets.
8. The apparatus of claim 7 , wherein there is a continuous surface without an inlet or outlet, extending between the plurality of outlets and the gas knife.
9. The apparatus of claim 7 , wherein the gas knife is positioned at a plan distance of between 0.2 mm and 3.0 mm from the outlets.
10. A device manufacturing method comprising:
projecting a patterned beam of radiation onto a substrate through a liquid provided in a space adjacent the substrate; and
containing the liquid in the space at least in part by pinning a meniscus of the liquid between adjacent outlets in a bottom surface of a liquid confinement structure using a gas flow generated by extraction of gas, from outside of the space, through the outlets, the outlets being distributed around the space such that the meniscus extends around the space, each outlet having a cross-sectional dimension of 0.2 mm or greater, and being, in plan, spaced apart from each other between 0.25 and 10 times their maximum plan dimension and two or more outlets of the plurality of the outlets not being at the bottom of a groove in the bottom surface.
11. The method of claim 10 , wherein each of the outlets are attached to a separate suction source.
12. The method of claim 10 , wherein each of the outlets is shaped such that two phase substantially annular flow exits through the outlets.
13. The method of claim 10 , wherein a surface of the liquid confinement system comprises a step change in distance between 0.2 mm and 10.0 mm radially outwardly of the outlets, the surface, in use, facing the substrate and the step change in distance extending away from the outlets in a direction away from the substrate.
14. The method of claim 10 , further comprising removing liquid through a further outlet positioned adjacent a corner of a plan shape in which the outlets are arranged.
15. The method of claim 10 , wherein each of the outlets is an outlet of an elongate passageway whose longitudinal axis is substantially perpendicular to the substrate.
16. The method of claim 10 , wherein the outlets are positioned relative to each other to form, in plan, a polygonal shape.
17. The method of claim 10 , further comprising supplying a gas from an inlet of the liquid confinement structure positioned radially outwardly of the outlets.
18. The method of claim 17 , wherein there is a continuous surface without an inlet or outlet, extending between the adjacent outlets and the inlet.
19. The method of claim 17 , wherein the inlet is positioned at a plan distance of between 0.2 mm and 3.0 mm from the outlets.
20. A liquid confinement structure to at least partly confine a liquid to a space between a projection system to project a patterned beam of radiation and a substrate, the liquid confinement structure comprising:
a plurality of outlets in a bottom surface of the liquid confinement structure, the plurality of outlets configured to remove liquid from the space and gas from outside the space to substantially pin a meniscus of the liquid in the space due to the creation of a gas flow, the outlets being distributed around the space such that the meniscus extends around the space, each outlet having a cross-sectional dimension of 0.2 mm or greater, and being, in plan, spaced apart from each other between 0.25 and 10 times their maximum plan dimension and two or more outlets of the plurality of the outlets not being at the bottom of a groove in the bottom surface.
21. The structure of claim 20 , wherein each of the outlets are attached to a separate suction source.
22. The structure of claim 20 , wherein each of the outlets is shaped such that two phase substantially annular flow exits through the outlets.
23. The structure of claim 20 , wherein a surface of the liquid confinement system comprises a step change in distance between 0.2 mm and 10.0 mm radially outwardly of the outlets, the surface, in use, facing the substrate and the step change in distance extending away from the outlets in a direction away from the substrate.
24. The structure of claim 20 , wherein each of the outlets is an outlet of an elongate passageway whose longitudinal axis is substantially perpendicular to the substrate.
25. The structure of claim 20 , further comprising a gas knife positioned radially outwardly of the outlets.
26. The structure of claim 25 , wherein there is a continuous surface without an inlet or outlet, extending between the plurality of outlets and the gas knife.
27. The structure of claim 25 , wherein the gas knife is positioned at a plan distance of between 0.2 mm and 3.0 mm from the outlets.