Lithographic apparatus and device manufacturing method

Abstract

A lithographic apparatus having a table including a target and/or a sensor and a liquid displacing device to displace liquid from the target and/or sensor using a localized gas flow is disclosed. The liquid displacement device may be positioned at various positions, e.g. mounted to a liquid handling device at an exposure station, adjacent or in a transfer path between the exposure station and a measurement station, at a load/unload station or adjacent a sensor.

1 . A lithographic apparatus comprising:
 a table configured to support a substrate, a sensor, or both the substrate and the sensor, the table having a sensor, a target for a sensor, or both the sensor and the target;   a liquid handling structure to confine liquid to a space adjacent the substrate and/or table; and   a liquid displacement device comprising a gas outlet configured to direct a localized gas flow toward the sensor and/or target so as to displace liquid from the sensor and/or target.   
     
     
         2 . The lithographic apparatus of  claim 1 , further comprising an alignment sensor and wherein the target includes a mark that is detectable by the alignment sensor. 
     
     
         3 . The lithographic apparatus of  claim 1 , further comprising a height sensor and wherein the target includes a reference plane for the height sensor. 
     
     
         4 . The lithographic apparatus of  claim 3 , wherein the height sensor is a gas gauge. 
     
     
         5 . The lithographic apparatus of  claim 1 , wherein the target includes a grid mounted to a surface of the table and the apparatus further comprises an encoder configured to measure displacement of the table in cooperation with the grid. 
     
     
         6 . The lithographic apparatus of  claim 1 , further comprising a positioner arranged to displace the table relative to the liquid displacement device. 
     
     
         7 . The lithographic apparatus of  claim 1 , wherein the gas flow is a gas knife. 
     
     
         8 . The lithographic apparatus of  claim 1 , wherein the liquid displacement device further comprises an opening configured to remove liquid. 
     
     
         9 . The lithographic apparatus of  claim 1 , further comprising:
 a measurement station having a sensor configured to measure a property of the table;   an exposure station having a projection system configured to project an image onto a substrate supported by the table; and   a table transfer device configured to transfer the table between the measurement and exposure stations along a transfer path,   wherein the liquid displacement device is positioned adjacent the transfer path.   
     
     
         10 . The lithographic apparatus of  claim 1 , further comprising a measurement station having a sensor configured to measure a property of the table, wherein the liquid displacement device is positioned in the measurement station. 
     
     
         11 . The lithographic apparatus of  claim 1 , further comprising a loading device configured to load a substrate onto the table, wherein the liquid displacement device is positioned adjacent the loading device. 
     
     
         12 . A device manufacturing method comprising:
 projecting an image of a pattern through an immersion liquid onto a first substrate held by a substrate table having a target, a sensor, or both the target and sensor;   unloading the first substrate from the substrate table;   loading a second substrate onto the substrate table;   measuring a property of the target or using the sensor; and   displacing liquid from the target and/or the sensor using a localized gas flow.   
     
     
         13 . The method of  claim 12 , wherein the displacing is performed at one or more of:
 after the unloading and before the loading;   in parallel with the unloading;   in parallel with the loading;   after the loading; or   after the projecting and before the unloading.   
     
     
         14 . The method of  claim 13 , wherein the displacing is performed after the projecting and after the unloading and the method further comprising transferring the substrate table from an exposure station to a loading station after the projecting and before the unloading, wherein the displacing is performed in parallel with the transferring, or before the transferring, or both. 
     
     
         15 . A device manufacturing method comprising:
 projecting an image of a pattern through an immersion liquid onto a first substrate held by a substrate table, the immersion liquid being provided between a projection system and the substrate by a liquid supply structure;   moving the liquid supply structure to a measurement table having a target, a sensor, or both the target and sensor, or moving the measurement table to the liquid supply structure;   unloading the first substrate from the substrate table;   loading a second substrate onto the substrate table;   measuring a property of the target or using the sensor; and   displacing liquid from the target and/or sensor using a localized gas flow.