Lithographic apparatus and device manufacturing method with bearing to allow substrate holder to float with respect to substrate table
A lithographic apparatus includes 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 including a substrate holder constructed to hold a substrate; and a projection system configured to project the patterned radiation beam onto a target portion of the substrate, wherein the substrate table is constructed and arranged to reduce or eliminate slip and hysteresis in position and orientation between the substrate table and the substrate holder.
1. A lithographic apparatus comprising:
a support constructed to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam;
a substrate table comprising a substrate holder constructed and arranged to hold a substrate, the substrate table, in use, being movable in a plane substantially parallel with a top surface of the substrate; and
a projection system configured to project the patterned radiation beam onto a target portion of the substrate,
wherein the substrate table comprises a bearing configured to support the substrate holder, the bearing allowing the substrate holder to float with respect to the substrate table,
wherein the substrate holder is connected to the substrate table with at least one physical connection, and
wherein the at least one physical connection comprises a flexure that holds the substrate holder movably in a radial direction of the substrate with respect to the substrate table.
2. The apparatus according to claim 1 , wherein the substrate holder is connected to the substrate table at a plurality of locations.
3. The apparatus according to claim 2 , wherein the substrate holder is connected, at a side thereof, via the at least one physical connection to a side wall of a recess in the substrate table, said recess accommodating the substrate holder.
4. The apparatus according to claim 1 , wherein the flexure is a leaf spring.
5. The apparatus according to claim 1 , wherein the at least one physical connection is a series of folded leaf springs.
6. The apparatus according to claim 1 , wherein the bearing comprises a gas bearing.
7. The apparatus according to claim 1 , wherein the bearing comprises flexure bearings.
8. The apparatus according to claim 1 , wherein the bearing comprises an active bearing.
9. The apparatus according to claim 8 , wherein the active bearing comprises one or more variable reluctance actuators.
10. The apparatus according to claim 8 , wherein the active bearing comprises one or more Lorenz actuators.
11. The apparatus according to claim 1 , further comprising a substrate table drive comprising a long stroke module configured to exert a force on a long stroke mover and a short stroke module configured to exert a force between the long stroke mover and the substrate table.
12. The apparatus according to claim 11 , wherein the long stroke module is configured to exert a force between the long stroke mover and the rest of the lithographic apparatus.
13. The apparatus according to claim 11 , wherein the long stroke module is configured to exert a force between the long stroke mover and a balance mass moveable within the lithographic apparatus.
14. The apparatus according to claim 1 , wherein, in use, the substrate table is subjected to accelerations and deceleration forces in a plane substantially perpendicular to a path of the patterned radiation beam.
15. The apparatus according to claim 1 , wherein the bearing is configured to support the substrate holder in a manner such that an entire lower surface of the substrate holder is uncoupled to the substrate table.
16. The apparatus according to claim 1 , wherein the substrate holder includes one or more sensors configured to measure a position and orientation of the substrate holder with respect to the substrate table.
17. The apparatus according to claim 16 , wherein the one or more sensors are capacitive sensors or optical encoders.
18. An apparatus comprising:
an object table constructed and arranged to be moveable in the apparatus;
an object holder provided on the object table, the object holder constructed to hold an object, the object table, in use, being movable in a plane substantially parallel with a top surface of the object; and
an object holder positioning system comprising a table drive comprising a long-stroke module configured to exert a force on a long stroke mover and a short-stroke module configured to exert a force between the long stroke mover and the object table,
wherein the object table comprises a bearing configured to support the object holder, the bearing allowing the object holder to float in a frictionless manner with respect to the object table, and
wherein the object holder is connected to the object table with at least one physical connection, and
wherein the at least one physical connection comprises a flexure that holds the substrate holder movably in a radial direction of the substrate with respect to the substrate table.
19. A device manufacturing method comprising:
holding an object with an object holder provided on an object table, the object table, in use, being movable in a plane substantially parallel with a top surface of the object;
exerting a force between a long stroke mover and the object table with a short-stroke module provided on an object table drive;
exerting a force between the long stroke mover and a machine base frame or balance mass with a long-stroke module provided on the object table drive; and,
keeping the object holder floating with respect to the object table with a bearing,
wherein the object holder is connected to the object table with at least one physical connection, and
wherein the at least one physical connection comprises a flexure that holds the substrate holder movably in a radial direction of the substrate with respect to the substrate table.
20. A lithographic apparatus comprising:
a support constructed to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam;
a substrate table comprising a substrate holder constructed and arranged to hold a substrate, the substrate table, in use, being movable in a plane substantially parallel with a top surface of the substrate; and
a projection system configured to project the patterned radiation beam onto a target portion of the substrate,
wherein the substrate table comprises a contact free bearing configured to support the substrate holder, the contact free bearing permitting relative movement of the substrate holder relative to the substrate table,
wherein the substrate holder is connected to the substrate table with at least one physical connection, and
wherein the at least one physical connection comprises a flexure that holds the substrate holder movably in a radial direction of the substrate with respect to the substrate table.
21. The apparatus according to claim 20 , wherein the contact free bearing is configured to permit relative movement of the substrate holder relative to the substrate table along a direction substantially perpendicular to a plane defined by a lower surface of the substrate holder.