Projection exposure apparatus and method

Abstract

Pattern transfer can be performed with improved exposure accuracy, by reducing the contamination caused by the attachment of a photosensitive agent or the like on an optical member of a projection optical member or the like. The pattern transfer onto a substrate W is performed after cleaning the objective member OB disposed at a given position by a cleaning device 8 at the time when pattern transfer is not performed, or while making flow a gas in a space between the substrate W and the optical member OB by a contamination protection device 98. Alternatively, the optical member OB disposed at a given position is inspected for contamination by a contamination inspection device 84 at the time when pattern transfer is not performed, and the pattern transfer or the cleaning or replacement of the optical member is performed based on the result.

1 . A projection exposure apparatus for transferring a pattern defined on a mask onto a substrate via a projection optical system, comprising: a cleaning device that cleans an optical member disposed at a given position  
     
     
         2 . The projection exposure apparatus according to  claim 1 , wherein the cleaning device is disposed on a stage for holding the substrate.  
     
     
         3 . The projection exposure apparatus according to  claim 2 , wherein the cleaning device is mounted on a vertical movement drive device provided on the stage.  
     
     
         4 . The projection exposure apparatus according to  claim 1 , wherein the cleaning device is mounted on a movable mechanism distinct from the stage for holding the substrate.  
     
     
         5 . The projection exposure apparatus according to  claim 4 , wherein the cleaning device comprises an ultrasonic cleaning device disposed on the movable mechanism to ultrasonically clean a part to be cleaned of the optical member by immersing the part to be cleaned of the optical member in a cleaning solution with ultrasonic vibration.  
     
     
         6 . The projection exposure apparatus according to  claim 4 , wherein the cleaning device comprises a cleaning member which contacts with the substrate-opposed surface of the optical member to the substrate-opposed surface.  
     
     
         7 . The projection exposure apparatus according to  claim 4 , wherein the cleaning device comprises a solution injector that emits a cleaning solution onto the substrate-opposed surface of the optical member.  
     
     
         8 . The projection exposure apparatus according to  claim 1 , wherein the cleaning device comprises an optical cleaning device that irradiates an irradiation light having an optically cleaning effect onto the surface of the optical member.  
     
     
         9 . The projection exposure apparatus according to  claim 8 , wherein the optical cleaning device comprises a gas supply device that supplies an oxidation-enhancing gas in the vicinity of the surface of the optical member.  
     
     
         10 . The projection exposure apparatus according to  claim 9 , wherein the optical cleaning device comprises a shield member disposed in the vicinity of the optical member to shield the atmosphere in the vicinity of the surface of the optical member, against the external environment.  
     
     
         11 . The projection exposure apparatus according to  claim 8 , wherein the optical cleaning device is adapted to irradiate the irradiation light onto the optical member through a replaceable window.  
     
     
         12 . The projection exposure apparatus according to  claim 1 , wherein the optical member is one disposed on the optical path of the exposure illumination light and in the most vicinity of the substrate.  
     
     
         13 . The projection exposure apparatus according to  claim 1 , wherein the optical member is, among a plurality of optical elements constituting the projection optical system, an optical element disposed in the most vicinity of the substrate.  
     
     
         14 . The projection exposure apparatus according to  claim 1 , wherein the optical member is one disposed at the end part of an optical system for alignment of the substrate.  
     
     
         15 . The projection exposure apparatus according to  claim 1 , wherein the apparatus includes a contamination inspection device that inspects the optical member for contamination.  
     
     
         16 . The projection exposure apparatus according to  claim 15 , wherein the cleaning device comprises a judging unit connected to the contamination inspection device to determine whether or not cleaning of the optical member is necessary, based on the inspection result from the contamination inspection device.  
     
     
         17 . A projection exposure apparatus for transferring a pattern defined on a mask onto a substrate via a projection optical system, comprising a contamination inspection device that inspects the optical member disposed in a given position for contamination.  
     
     
         18 . The projection exposure apparatus according to  claim 17 , the contamination inspection device comprises: 
 an irradiation optical system that irradiats light to the optical member;    a photodetector that detects the light from the optical member; and    a contamination inspection data processing unit connected to the photodetector to inspect the optical member for contamination based on the detection result from the photodetector.    
     
     
         19 . The projection exposure apparatus according to  claim 17 , wherein the optical member is one disposed on the optical path of the exposure illumination light and in the most vicinity of the substrate.  
     
     
         20 . The projection exposure apparatus according to  claim 17 , wherein the optical member is one disposed at the end part of an optical system for alignment of the substrate.  
     
     
         21 . The projection exposure apparatus according to  claim 18 , wherein the inspection device measures a reflectance of a reflection light reflected on the surface of the optical member or a transmittance of a transmission light passed through the surface of the optical member, and then determines the contamination level of the surface of the optical member based on the measurement result.  
     
     
         22 . The projection exposure apparatus according to  claim 21 , wherein the inspection device determines the contamination level of the surface of the optical member based on the comparison result between a preset given reflectance of transmittance and an actually measured real reflectance or transmittance, respectively.  
     
     
         23 . The projection exposure apparatus according to  claim 22 , wherein the inspection device measures a reflectance of a reflection light reflected on the surface of the optical member or a transmittance of a transmitted light passed through the surface of the optical member, and then determines a real reflectance or transmittance from the comparison result between a photoelectric signal for the irradiation light received after reflected on the surface of the optical member or after passed through the surface of the optical member and a photoelectric signal for the irradiation light received without the presence of the optical member.  
     
     
         24 . The projection exposure apparatus according to  claim 17 , wherein the apparatus includes a cleaning device that cleans the optical member.  
     
     
         25 . The projection exposure apparatus according to  claim 24 , wherein the cleaning device comprises an optical cleaning device that irradiates an irradiation light having an optical cleaning effect onto the surface of the optical member.  
     
     
         26 . A projection exposure apparatus for transferring a pattern defined on a mask onto a substrate via a projection optical system, comprising a contamination protection device that makes flow the a gas between the optical member disposed in the vicinity of the exposure surface of the substrate and the substrate to prevent the approach of contaminants generated from the substrate to the optical member.  
     
     
         27 . The projection exposure apparatus according to  claim 26 , wherein the contamination protection device comprises: 
 a flow-path setting member that sets the flow path of the gas in the vicinity of the substrate-opposed surface of the optical member; and    a gas supply unit communicated with the flow-path setting member to supply the gas to the flow path set by the flow-path setting member.    
     
     
         28 . The projection exposure apparatus according to  claim 27 , wherein the optical member is one disposed on the optical path of the exposure illumination light and in the most vicinity of the substrate.  
     
     
         29 . The projection exposure apparatus according to  claim 27 , wherein the optical member is one disposed at the end part of an optical system for alignment of the substrate.  
     
     
         30 . A projection exposure method for transferring a pattern defined on a mask onto a substrate via a projection optical system, the method comprising: 
 removing the contamination on an optical member disposed at a given position; and    transferring a pattern defined on the mask onto the substrate via the projection optical system.    
     
     
         31 . The projection exposure method according to  claim 30 , wherein the optical member is one disposed on the optical path of the exposure illumination light and in the most vicinity of the substrate.  
     
     
         32 . The projection exposure method according to  claim 30 , wherein the method further comprises, prior to the cleaning step, determining the relation between the contamination level of the optical member and the number of pattern transfer operations and then determining the limit in number of pattern transfer operations, which is the number of exposure operations during which the clean substrate-opposed surface of the optical member is contaminated to a predetermined impermissible level; and the cleaning step is performed before the number of pattern transfer operations performed after the previous cleaning step exceeds the limit.  
     
     
         33 . A projection exposure method for transferring a pattern defined on a mask onto a substrate via a projection optical system, the method comprising: 
 inspecting an optical member disposed at a predetermined for contamination; and    determining whether or not pattern transfer may be performed based on the inspection result obtained in the inspection step.    
     
     
         34 . The projection exposure method according to  claim 30 , wherein the cleaning step comprises irradiating an irradiation light having an optical cleaning effect onto the contamination attached on the optical member.  
     
     
         35 . The projection exposure method according to  claim 33 , wherein the method further comprises: removing the contamination on the optical member based on the inspection result obtained in the inspection step.  
     
     
         36 . A method for assembling a projection exposure apparatus for transferring a pattern defined on a mask onto a substrate via a projection optical system, the method comprising: providing a cleaning device that cleans an optical member disposed at a given position, to the projection exposure apparatus.  
     
     
         37 . The method according to  claim 36 , wherein the cleaning device is an optical cleaning device that irradiats an irradiation light having an optical cleaning effect onto the contamination attached on the optical member.  
     
     
         38 . The method according to  claim 37 , wherein the method further comprises providing a contamination inspection device that inspects the optical member for contamination, to the projection exposure apparatus.  
     
     
         39 . A projection exposure apparatus for transferring a pattern defined on a mask onto a substrate via a projection optical system, comprising: a cleaning device that cleans an optical member disposed in the vicinity of the substrate.  
     
     
         40 . A projection exposure apparatus for transferring a pattern defined on a mask onto a substrate via a projection optical system, comprising: a contamination inspection device that inspects an optical member disposed in the vicinity of the substrate for contamination.  
     
     
         41 . A projection exposure method for transferring a pattern defined on a mask onto a substrate via a projection optical system, the method comprising: 
 removing the contamination on an optical member disposed in the vicinity of the substrate; and    transferring a pattern defined on the mask onto the substrate via the projection optical system.    
     
     
         42 . A projection exposure method for transferring a pattern defined on a mask onto a substrate via a projection optical system, the method comprising: 
 inspecting an optical member disposed in the vicinity of the substrate for contamination; and    determining whether or not pattern transfer may be performed based on the inspection result obtained in the inspection step.    
     
     
         43 . A method for assembling a projection exposure apparatus for transferring a pattern defined on a mask onto a substrate via a projection optical system, the method comprising: providing a cleaning device that cleans an optical member disposed in the vicinity of the substrate, to the projection exposure apparatus.