Lithographic apparatus and device manufacturing method
A porous member is used in a liquid removal system of an immersion lithographic projection apparatus to smooth uneven flows. A pressure differential across the porous member may be maintained at below the bubble point of the porous member so that a single-phase liquid flow is obtained. Alternatively, the porous member may be used to reduce unevenness in a two-phase flow.
1. A lithographic projection apparatus configured to project a patterned beam onto a substrate using a projection system and configured to supply liquid to a space between the projection system and the substrate using a liquid supply system, the apparatus comprising:
a substrate table configured to hold a substrate, the substrate table comprising a recess configured to receive the substrate, wherein the recess is larger than the substrate such that a trench is provided around an edge of the substrate when the substrate is held by the substrate table, the trench configured to collect at least part of the liquid;
a liquid confinement member configured to at least partly confine the liquid in the space between the projection system and a surface of the substrate, the substrate table or both; and
a removal opening comprising a porous member facing the substrate and vertically spaced apart from a bottom surface of the substrate, when the substrate is located under the projection system and the removal opening configured to remove at least part of the liquid through the porous member.
2. The apparatus of claim 1 , wherein the removal opening is configured to remove liquid through the porous member in a two phase flow.
3. The apparatus of claim 2 , wherein the removal opening is connected to a chamber configured to remove liquid in a two phase flow.
4. The apparatus of claim 1 , wherein the removal opening comprises a rectangular shape around a path of the patterned beam.
5. The apparatus of claim 1 , wherein the liquid confinement member comprises a surface configured to form a passage with a facing surface of the substrate and/or substrate table, the removal opening provided in the surface configured to form the passage.
6. The apparatus of claim 1 , wherein liquid or gas is selectively removed from the trench.
7. The apparatus of claim 1 , further comprising a liquid channel connected to the trench, the liquid channel configured to drain liquid separately from gas via the trench.
8. The apparatus of claim 1 , wherein the trench is configured to collect and remove liquid so that there is a flow of liquid downwards.
9. The apparatus of claim 1 , wherein the liquid confinement member has an inner periphery and wherein, at a bottom end of the inner periphery, the inner periphery closely conforms to the shape of the image field.
10. The apparatus of claim 9 , wherein the image field is essentially rectangular.
11. The apparatus of claim 9 , wherein, at an upper end of the inner periphery, the inner periphery closely conforms to the shape of the projection system.
12. A lithographic projection apparatus configured to project a patterned beam onto a substrate using a projection system, the lithographic projection apparatus comprising:
a liquid supply system configured to supply a liquid to a space between the projection system and the substrate;
a substrate table configured to support the substrate, the substrate table comprising a recess to receive the substrate so that a trench is formed around the edge of the substrate, the trench arranged to collect at least part of the liquid;
a liquid confinement member configured to at least partly confine liquid to the space, the liquid confinement member comprising:
a porous member located in an undersurface of the liquid confinement member, and through which liquid is extracted from the space;
a manifold configured to receive a fluid flow from the porous member, the manifold configured to separate liquid and gas present in the fluid flow.
13. The apparatus of claim 12 , wherein the manifold comprises a gas outlet that is located at the top of the manifold and configured to remove gas from the manifold.
14. The apparatus of claim 12 , wherein the manifold comprises a liquid removal pipe, a liquid opening of the liquid removal pipe towards the bottom of the manifold, the liquid opening and liquid removal pipe configured to remove liquid from the manifold under suction.
15. The apparatus of claim 12 , wherein the manifold is thermally isolated from its surroundings.
16. The apparatus of claim 12 , wherein the porous member is configured to remove liquid through the porous member in a two phase flow.
17. The apparatus of claim 12 , wherein the porous member comprises a rectangular shape around a path of the patterned beam.
18. The apparatus of claim 12 , wherein the liquid confinement member has an inner periphery and wherein, at a bottom end of the inner periphery, the inner periphery closely conforms to the shape of the image field.
19. The apparatus of claim 12 , wherein the trench is configured to collect and remove liquid so that there is a flow of liquid downwards.
20. A device manufacturing method, comprising:
holding a substrate in a recess of a substrate table, wherein the recess is larger than the substrate such that a trench is provided around an edge of the substrate when the substrate is held by the substrate table;
supplying a liquid, using a liquid supply system, into a space between a projection system and a substrate;
projecting a patterned beam through the liquid onto a substrate using the projection system, the substrate supported by a substrate table and the projection system located above the substrate, the liquid located in a space between the projection system, and the substrate, the substrate table or both;
confining the liquid to the space at least partly using a liquid confinement member;
removing at least part of the liquid through a porous member, the porous member provided in a removal opening and the porous member facing the substrate and vertically spaced apart from a bottom surface of the substrate; and
collecting at least part of the liquid in the trench.