Lithographic apparatus and device manufacturing method

Abstract

A map of the surface of a substrate is generated at a measurement station. The substrate is then moved to where a space between a projection lens and the substrate is filled with a liquid. The substrate is then aligned using, for example, a transmission image sensor and, using the previous mapping, the substrate can be accurately exposed. Thus the mapping does not take place in a liquid environment.

1 - 3 . (canceled) 
     
     
         4 . A method of patterning a substrate, the method comprising:
 measuring a substrate while a target portion of the substrate is submerged in a first liquid;   after the measuring, removing the first liquid from the target portion, and   after the removing, providing a second liquid in a space between a projection system and the substrate and projecting a patterned beam through the second liquid onto the target portion of the substrate.   
     
     
         5 . The method of  claim 4 , wherein the first liquid is different from the second liquid. 
     
     
         6 . The method of  claim 4 , further comprising, after removing the first liquid and before providing the second liquid, moving the substrate from a first location where the substrate is measured to a second location under the projection system. 
     
     
         7 . The method of  claim 6 , wherein a measurement station is provided at the first location. 
     
     
         8 . The method of  claim 7 , wherein the measurement station is configured to provide a level of the substrate. 
     
     
         9 . The method of  claim 4 , wherein the measuring comprises measuring a height, a tilt, or both, of each of a plurality of points on the substrate. 
     
     
         10 . The method of  claim 4 , wherein measuring the substrate at least partially overlaps in time with exposure of a further substrate using the projection system. 
     
     
         11 . The method of  claim 10 , wherein the substrate and the further substrate are arranged on separate substrate tables. 
     
     
         12 . The method of  claim 11 , wherein the separate substrate tables are each movable between a measurement station where the measuring is performed and an exposure station where the projection system is located. 
     
     
         13 . The method of  claim 4 , comprising generating a map of the substrate based on the measuring. 
     
     
         14 . The method of  claim 4 , wherein the measuring is performed at a measurement station and the projecting is performed at an exposure station and wherein the measurement station is physically separated from the exposure station. 
     
     
         15 . The method of  claim 14 , further comprising supplying the first liquid with a first liquid supply system in the vicinity of the measurement station and supplying the second liquid with a second liquid system. 
     
     
         16 . The method of  claim 4 , wherein said second liquid is in contact with a last element of the projection system and the substrate during projection of the patterned beam of radiation. 
     
     
         17 . A lithographic apparatus, comprising:
 a measurement station configured to measure a substrate while a target portion of the substrate is submerged in a first liquid;   an exposure station including a projection system configured to project a patterned beam of radiation through a second liquid onto the target portion of a substrate, and   a liquid retrieval system configured to remove the first liquid from the target portion after the substrate is measured at the measurement station and before the second liquid is provided between the projection system and the substrate.   
     
     
         18 . The lithographic apparatus of  claim 17 , wherein the first liquid is different from the second liquid. 
     
     
         19 . The lithographic apparatus of  claim 17 , further comprising a substrate table to support the substrate, the substrate table being movable from the measurement station to the exposure station. 
     
     
         20 . The lithographic apparatus of  claim 17 , wherein the measurement station is configured to provide a level of the substrate. 
     
     
         21 . The lithographic apparatus of  claim 17 , wherein the measurement station is configured to measure a height, a tilt, or both, of each of a plurality of points on the substrate. 
     
     
         22 . The lithographic apparatus of  claim 17 , wherein a measurement of the substrate at the measurement station least partially overlaps in time with exposure of a further substrate using the projection system. 
     
     
         23 . The lithographic apparatus of  claim 22 , wherein the substrate and the further substrate are arranged on separate substrate tables.