Exposure apparatus

Abstract

In the exposure apparatus of the present invention, a sealed chamber defined by a first lens and a second lens in an input lens system on a plane of incidence of a fly-eye lens in an illumination optical system is provided. In a gas exchanging step, the impurity gas in the sealed chamber is first exhausted through an electromagnetic valve provided with a check valve and a gas exhaust pipe, using a gas exhaust pump and then, a high-purity nitrogen gas is supplied from a gas bomb through a gas supply pipe and an electromagnetic valve provided with a check valve to the sealed chamber. Using a pressure sensor provided in the sealed chamber, the gas exchanging step is repeated while maintaining an amount of change in pressure in the sealed chamber within a predetermined allowable range, to thereby reduce the concentration of impurities in the gas in the sealed chamber to a target value.

What is claimed is:  
     
         1 . An exposure apparatus for illuminating a pattern on a mask with exposure light passing through an illumination optical system, to thereby transfer said pattern on the mask to a substrate, comprising: 
 a sealed chamber provided in an optical path of said exposure light in said illumination optical system,    said sealed chamber containing a gas and shielded from a gas surrounding said sealed chamber in said illumination optical system; and    a gas exchanging device adapted to exchange the gas in said sealed chamber with a predetermined gas.    
     
     
         2 . The exposure apparatus according to    claim 1   , wherein said gas exchanging device comprises: 
 a gas exhausting system adapted to exhaust the gas in said sealed chamber;    a gas supplying system adapted to supply the predetermined gas to said sealed chamber;    a pressure sensor provided in said sealed chamber to detect a pressure in said sealed chamber; and    a control system adapted to control an operation of each of said gas exhausting system and said gas supplying system, based on said pressure in the sealed chamber detected by said pressure sensor, to thereby exchange the gas in said sealed chamber with the predetermined gas.    
     
     
         3 . The exposure apparatus according to    claim 2   , wherein when the gas in said sealed chamber is exchanged with the predetermined gas, said control system enables said gas exhausting system to exhaust the gas in said sealed chamber and said gas supplying system to supply the predetermined gas to said sealed chamber, while maintaining an amount of change in said pressure in the sealed chamber detected by said pressure sensor within a predetermined allowable range.  
     
     
         4 . The exposure apparatus according to    claim 1   , wherein said illumination optical system comprises: 
 a light source adapted to emit exposure light;    a shaping optical system adapted to shape said exposure light passing therethrough; and    an optical integrator adapted to enable said exposure light to have a uniform illuminance distribution after passing through said shaping optical system, and said sealed chamber is defined by two optical members constituting said shaping optical system.    
     
     
         5 . The exposure apparatus according to    claim 1   , wherein an inert gas is contained in said sealed chamber.  
     
     
         6 . The exposure apparatus according to    claim 1   , wherein said sealed chamber is provided at a position at which said exposure light exhibits high illuminance.  
     
     
         7 . The exposure apparatus according to    claim 1   , wherein said illumination optical system includes an input lens system and said sealed chamber is provided in said input lens system.  
     
     
         8 . The exposure apparatus according to    claim 1   , further comprising a device adapted to maintain a temperature of the gas in said sealed chamber at a predetermined level.  
     
     
         9 . The exposure apparatus according to    claim 1   , wherein the gas in said sealed chamber is exchanged periodically during idling of said exposure apparatus.  
     
     
         10 . The exposure apparatus according to    claim 1   , wherein the gas in said sealed chamber is exchanged during assembly and adjustment of said exposure apparatus.  
     
     
         11 . A method for conducting an exchange of gases in a sealed chamber provided in an exposure apparatus, comprising a gas exchanging step including: 
 a first sub-step of exhausting a gas in said sealed chamber from a gas exhaust side thereof, while said sealed chamber is closed on a gas supply side thereof; and    a second sub-step of supplying an inert gas to said sealed chamber from the gas supply side thereof, while said sealed chamber is closed on the gas exhaust side thereof,    wherein each of said first sub-step and said second sub-step is conducted in a substantially stationary state with respect to a pressure of the gas in said sealed chamber.    
     
     
         12 . The method according to    claim 11   , wherein said exchange of gases in said sealed chamber is conducted periodically during idling of said exposure apparatus.  
     
     
         13 . The method according to    claim 11   , wherein said exchange of gases in said sealed chamber is conducted during assembly and adjustment of said exposure apparatus.  
     
     
         14 . The method according to    claim 11   , wherein in said first sub-step, a part of the gas in said sealed chamber is exhausted from the gas exhaust side of said sealed chamber and said gas exchanging step is conducted at least twice, and said method further comprises a step of measuring a total gas exchange time by counting the number of times said gas exchanging step is conducted.  
     
     
         15 . The method according to    claim 14   , wherein said exchange of gases is conducted periodically during idling of said exposure apparatus and said method further comprises the steps of: 
 measuring an idling time of said exposure apparatus; and    comparing said idling time with said total gas exchange time, and when said total gas exchange time exceeds said idling time, a time for conducting said gas exchanging step at one time is reduced.    
     
     
         16 . An exposure apparatus comprising: 
 an illumination optical system adapted to emit exposure light, said exposure light being adapted to illuminate a mask pattern to thereby transfer said mask pattern to a substrate;    a sealed chamber provided in said illumination optical system; and    a gas exchanging device adapted to exhaust a gas in said sealed chamber and supply an inert gas to said sealed chamber.    
     
     
         17 . The exposure apparatus according to    claim 16   , wherein said illumination optical system includes an input lens system, said input lens system having at least one pair of lenses, and said sealed chamber is defined by said at least one pair of lenses.  
     
     
         18 . The exposure apparatus according to    claim 17   , wherein said gas exchanging device comprises: 
 a gas exhausting system adapted to exhaust an impurity gas in said sealed chamber;    a gas supplying system adapted to supply an inert gas to said sealed chamber; and    a control system adapted to control said gas exhausting system and said gas supplying system so that a change in pressure in said sealed chamber is within a predetermined range.    
     
     
         19 . The exposure apparatus according to    claim 18   , wherein said gas exhausting system includes: 
 a gas exhaust pipe adapted to exhaust said impurity gas from said sealed chamber;    an electromagnetic valve provided in said gas exhaust pipe to open and close said gas exhaust pipe, said electromagnetic valve being provided with a check valve; and    a gas exhaust pump connected to a gas exhaust side of said electromagnetic valve in the gas exhaust pipe,    wherein said gas supplying system includes:    a gas supply pipe adapted to supply said inert gas to said sealed chamber;    an electromagnetic valve provided in said gas supply pipe to open and close said gas supply pipe, said electromagnetic valve being provided with a check valve; and    a gas bomb connected to a gas supply side of said electromagnetic valve in the gas supply pipe, and    wherein said control system is adapted to control said electromagnetic valve in the gas exhaust pipe and said electromagnetic valve in the gas supply pipe.    
     
     
         20 . A projection exposure apparatus for transferring a pattern on a mask to a photosensitive substrate, comprising: 
 a light source adapted to emit exposure light having a wavelength range in which a photosensitive substrate is sensitive to said exposure light;    an illumination optical system provided between said light source and said mask;    a projection optical system provided between said mask and said photosensitive substrate;    a sealed chamber containing a gas and provided in an optical path of said exposure light between said light source and said photosensitive substrate; and    a gas circulating device connected to said sealed chamber,    said gas circulating device being adapted to exhaust the gas contained in said sealed chamber to an outside thereof, to thereby compensate for variations in intensity of said exposure light on said photosensitive substrate.    
     
     
         21 . The apparatus according to    claim 20   , wherein said sealed chamber is defined by at least two optical members provided in said illumination optical system.  
     
     
         22 . The apparatus according to    claim 20   , wherein said gas circulating device is adapted to supply nitrogen or helium to said sealed chamber.  
     
     
         23 . A projection exposure apparatus for transferring a pattern on a mask to a photosensitive substrate, comprising: 
 a light source adapted to emit exposure light having a wavelength range in which a photosensitive substrate is sensitive to said exposure light;    a sealed chamber provided in an optical path of said exposure light between said light source and said photosensitive substrate; and    a gas circulating device having a sensor and connected to said sealed chamber,    said sensor being adapted to detect and output information corresponding to a pressure in said sealed chamber, and    said gas circulating device being adapted to supply an inert gas to said sealed chamber in accordance with the information outputted from said sensor.    
     
     
         24 . A method for transferring a pattern on a mask to a photosensitive substrate, comprising the steps of: 
 illuminating said mask with exposure light, to thereby transfer said pattern on the mask to a photosensitive substrate; and    exchanging an inert gas contained in a sealed chamber with another gas,    said sealed chamber being provided in an optical path of said exposure light,    to thereby compensate for variations in light transmittance and light reflectance of an optical member provided in said optical path of the exposure light.    
     
     
         25 . An exposure apparatus for transferring a pattern on a mask to a photosensitive substrate, comprising: 
 an optical system adapted to allow exposure light to enter,    said exposure light being adapted to be irradiated to a photosensitive substrate; and    a device adapted to supply a gas capable of suppressing attenuation of said exposure light to said optical system, according to a change in light transmittance of said optical system which occurs due to entrance of said exposure light.    
     
     
         26 . A method for making an apparatus for transferring a pattern on a mask to a photosensitive substrate, comprising the steps of: 
 providing an optical system between a light source and a photosensitive substrate,    said light source being adapted to emit exposure light,    said exposure light being adapted to enter said optical system and irradiate said photosensitive substrate; and    providing a device adapted to supply a gas capable of suppressing attenuation of said exposure light to said optical system, according to a change in light transmittance of said optical system.