Lithographic apparatus and device manufacturing method
An immersion lithographic apparatus has a barrier member surrounding a space between the projection system and the substrate so as to at least partly confine liquid in the space. A jet of liquid is directed radially inwardly in a gap between the barrier member and the substrate and/or between the barrier member and the projection system, to help prevent escape of liquid.
1. A lithographic apparatus, comprising:
a projection system configured to project an image of a desired pattern through a liquid onto an image field;
a substrate table configured to hold a substrate so that a target portion on the substrate is positionable in the image field;
a barrier member configured to surround, and to at least partly confine liquid to, a space between the projection system and an immersion surface, the immersion surface being that of the substrate, the substrate table, or both the substrate and the substrate table, the barrier member comprising:
a surface facing the immersion surface so as to define a gap between the barrier member and the immersion surface;
an extraction outlet, having a sieve, to extract fluid from the gap, the sieve having a surface closest to the immersion surface farther from the immersion surface than another surface of the barrier member;
a plate located between the extraction outlet and the image field and extending around the image field; and
an inlet, located above the plate and between the plate and the projection system, for connection to a source of liquid, the inlet configured to supply liquid to the space in the form of a plurality of jets and in a direction toward the image field.
2. The apparatus of claim 1 , further comprising a liquid drain located between the inlet and the projection system to remove liquid.
3. The apparatus of claim 1 , wherein the inlet is located between the extraction outlet and the image field.
4. The apparatus of claim 1 , wherein the inlet comprises a plurality of nozzles spaced around the barrier member so as to substantially surround the image field.
5. The apparatus of claim 1 , wherein the barrier member comprises a further inlet located on the surface facing the immersion surface to supply liquid to the gap.
6. The apparatus of claim 1 , wherein, in use, the gap is smaller outward, relative to the image field, from the extraction outlet than at the extraction outlet or than inward, relative to the image field, of the extraction outlet.
7. The apparatus of claim 1 , wherein the barrier member has an outer surface that is outward, relative to the image field, from the extraction outlet and closer, in use, to the immersion surface than the sieve of the extraction outlet, the outer surface extending to the periphery of the barrier member and having no openings therein.
8. The apparatus of claim 1 , wherein the extraction outlet is a single phase extractor configured to extract substantially only liquid.
9. The apparatus of claim 1 , wherein the inlet is located between the plate and a final surface, nearest to the immersion surface, of the projection system.
10. A device manufacturing method, comprising:
supplying a liquid to a space between a projection system and a substrate in the form of a plurality of jets in a direction toward an image field using an inlet, the inlet located between a plate of a barrier member and the projection system and above the plate, wherein the barrier member surrounds the liquid and at least partly confines the liquid to the space;
flowing liquid through an aperture in the plate to a gap between the substrate and a surface of the barrier member facing the substrate, the plate located between an extraction outlet of the barrier member and the image field and the plate extending around the image field;
extracting fluid from the gap through an extraction outlet, the extraction outlet having a sieve, the sieve having a surface closest to the substrate farther from the substrate than another surface of the barrier member;
positioning the substrate so that a target portion on the substrate is positioned in the image field; and
projecting an image of a desired pattern through the liquid in the space between the projection system and the substrate onto the target portion of the substrate.
11. The method of claim 10 , further comprising removing liquid using a drain located between the inlet and the projection system.
12. The method of claim 10 , wherein the inlet is located between the extraction outlet and the image field.
13. The method of claim 10 , further comprising supplying liquid to the gap from a further inlet located on the surface facing the substrate.
14. The method of claim 10 , wherein extracting fluid from the gap through the extraction outlet comprises removing substantially only liquid.
15. A lithographic apparatus, comprising:
a projection system configured to project an image of a desired pattern through a liquid onto an image field;
a substrate table configured to hold a substrate so that a target portion on the substrate is positionable in the image field;
a barrier member configured to surround, and to at least partly confine liquid to, a space between the projection system and an immersion surface, the immersion surface being that of the substrate, the substrate table, or both the substrate and the substrate table, the barrier member comprising:
a surface facing the immersion surface so as to define a gap between the barrier member and the immersion surface;
an extraction outlet, having a sieve, to extract fluid from the gap;
a plate located between the extraction outlet and the image field and extending around the image field;
an inlet, located between the plate and the projection system, for connection to a source of liquid, the inlet configured to supply liquid to the space and in a direction toward the image field; and
a drain located between the inlet and the projection system to extract fluid from the space.
16. A lithographic apparatus, the apparatus comprising:
a projection system configured to project an image of a desired pattern through a liquid onto an image field;
a substrate table configured to hold a substrate so that a target portion on the substrate is positionable in the image field;
a barrier member configured to surround a space between the projection system and the substrate, the substrate table, or both the substrate and the substrate table, the barrier member configured to at least partly confine liquid to the space and having a surface facing the substrate, the substrate table, or both the substrate and the substrate table, so as to define a gap between the barrier member and the substrate, the substrate table, or both the substrate and the substrate table; and
a nozzle for connection to a source of liquid, the nozzle shaped and oriented to direct a jet of liquid into the gap and substantially angled towards the center of the image field and the nozzle having an opening which is the most radially outward positioned opening defined in the surface facing the substrate, the substrate table, or both the substrate and the substrate table, of the barrier member.
17. The apparatus of claim 16 , further comprising a liquid supply connected to the nozzle and arranged to supply liquid to the nozzle at a pressure such that a rate of momentum transfer from the jet to the liquid confined in the space is sufficient to prevent liquid flowing away from the space through the gap.
18. The apparatus of claim 16 , further comprising a liquid supply connected to the nozzle and arranged to supply liquid to the nozzle at a pressure such that a velocity of the liquid is greater than a relative speed of the substrate and the projection system during a scanned exposure.
19. A lithographic apparatus, the apparatus comprising:
a projection system configured to project an image of a desired pattern through a liquid onto an image field, the projection system having a bottom optical surface;
a substrate table configured to hold a substrate so that a target portion on the substrate is positionable in the image field;
a barrier member configured to surround, and to at least partly confine liquid to, a space between the projection system and an immersion surface, the immersion surface being that of the substrate, the substrate table, or both the substrate and the substrate table, the barrier member having a surface facing the projection system so as to define a gap between the barrier member and the projection system and having a plate portion located between the bottom optical surface and the image field and extending around the image field; and
a nozzle, located above the plate and between the plate and the projection system, for connection to a source of liquid, the nozzle having an outlet below the bottom optical surface and shaped and oriented to direct a plurality of jets of liquid into the gap.
20. The apparatus of claim 19 , wherein the nozzle is shaped and oriented to direct the jet downwards and toward the image field.