Position transducer and exposure apparatus with same

Abstract

The exposure apparatus is provided in its main body portion with laser diodes each having different wavelengths, for illuminating light for alignment onto a mark of a grating form arranged on each of a reticle and a wafer. The main body portion of the exposure apparatus has photomultipliers for receiving the diffraction light returned from each of the reticle mark and the wafer mark. The alignment of the reticle mark with the wafer mark is implemented by comparing phase differences of optical beat signals converted photoelectrically by the photomultipliers and by means of a phase detection comparison system. The light fluxes are transmitted between photomultipliers the laser diodes and the alignment optical system disposed in the main body portion thereof through optical fibers. This arrangement enables the position transducer to reduce an influence of generated heat upon the position detection of the wafer as well as the exposure apparatus, even if a photodetector having a large calorific power is employed.

What is claimed is:  
     
         1 . A position transducer for detecting a position of an substrate, comprising: 
 an illumination optical system for illuminating a light flux for detecting the position of said substrate on a mark for position detection provided on said substrate;    a photodetector for receiving the light flux from said mark for position detection; and    plural optical guides for leading the light flux returning from said mark for position detection to said photodetector.    
     
     
         2 . A position transducer as claimed in    claim 1   , wherein: 
 said light flux for position detection comprises a light flux of multiple wavelengths; and    the light flux from said mark for position detection is led to said photodetector through said plural optical guide different for each wavelength.    
     
     
         3 . A position transducer as claimed in    claim 2   , wherein each of said plural optical guides comprises an optical fiber with a propagation efficiency optimized for the wavelength of the light flux as an object of propagation.  
     
     
         4 . A position transducer as claimed in any one of    claims 1    to    3   , wherein: 
 said mark for position detection comprises a mark of a diffraction grating form arranged by a predetermined pitch in a direction of measurement;  
 said illumination optical system comprises an optical system for illuminating mutually coherent multiple light fluxes as said light flux for position detection on the mark of the diffraction grating form from different directions;  
 said photodetector comprises first and second photodetectors, wherein:  
 the first photodetector is to receive first interference light comprised of multiple diffraction light generating in a direction parallel to a first direction from the mark of the diffraction grating form; and  
 the second photodetector is to receive second interference light comprised of multiple diffraction light generating in a direction parallel to a second direction yet different from the first direction from the mark of the diffraction grating form; and  
 said optical guide comprises two optical guides for leading said first and second diffraction light independently from each other to the respective photodetectors.  
 
     
     
         5 . A position transducer as claimed in any one of    claims 1    to    4   , wherein: 
 said light flux for position detection comprises light flux of multiple wavelengths; and  
 the light flux of multiple wavelengths is led to said illumination optical system via multiple optical guides different for each wavelength.  
 
     
     
         6 . A position transducer as claimed in any one of    claims 1    to    5   , wherein: 
 said first interference light comprised of multiple diffraction light generating in the direction parallel to the first direction from the mark of the diffraction grating form is led to said first photodetector via said optical guide after separation into each of the wavelengths of the light flux; and  
 said second interference light comprised of multiple diffraction light generating in the direction parallel to the second direction yet different from the first direction from the mark of the diffraction grating form is led to said second photodetector via said optical guide after separation into each of the wavelengths of the light flux.  
 
     
     
         7 . A position transducer as claimed in any one of    claims 1    to    5   , wherein: 
 said first interference light comprised of multiple diffraction light generating in the direction parallel to the first direction from the mark of the diffraction grating form is led to a position in the vicinity of said first photodetector via said optical guide before separation into each of the wavelengths of the light flux; and  
 said second interference light comprised of multiple diffraction light generating in the direction parallel to the second direction yet different from the first direction from the mark of the diffraction grating form is led to a position in the vicinity of said second photodetector via said optical guide before separation into each of the wavelengths of the light flux.  
 
     
     
         8 . An exposure apparatus for transcribing a mask pattern on a photosensitizable substrate, having a position transducer as claimed in any one of    claims 1    to    7   , wherein: 
 said mark for position detection on said photosensitizable substrate is detected given by said position transducer as a mark for position detection on the substrate to be detected; and  
 said photosensitizable substrate is aligned on the basis of a result of detection given by said position transducer.  
 
     
     
         9 . An exposure apparatus having a main body portion for transcribing a mask pattern on a photosensitizable substrate and a position detection system for detecting a position of a mark for position detection formed on said photosensitizable substrate and having said main body portion and said position detection system arranged so as to align said mask pattern with said photosensitizable substrate on the basis of a result of detection of a position of said mask pattern detected by said position detection system; wherein: 
 said position detection system comprises a laser light source for generating laser light with multiple wavelengths, an illumination optical system for illuminating the laser light from said laser light source onto the mark for position detection formed on said photosensitizable substrate, and a light recipient optical system for receiving light returning from said mark for position detection; and    said laser light source is isolated from said main body portion of said exposure apparatus.    
     
     
         10 . An exposure apparatus as claimed in    claim 9   , wherein the laser light of multiple wavelength from said laser light source is led to said illumination optical system through the optical guides different for each wavelength.  
     
     
         11 . An exposure apparatus as claimed in    claim 9    or    10   , wherein said light recipient optical system is to receive diffraction light generated in a predetermined direction by said laser light from said mark for position detection.  
     
     
         12 . An exposure apparatus as claimed in    claim 8   , wherein: 
 said illumination optical system is to illuminate said laser light of multiple wavelengths on a mark of a linear dot arrangement as said mark for position detection and to detect a position of the mark of the linear dot arrangement on the basis of a light amount of the diffraction light to be received by said light recipient optical system.    
     
     
         13 . An exposure apparatus comprising: 
 a main body portion having an illumination optical system and arranged to transcribe a mask pattern of a reticle on a wafer by light for exposure generating from said illumination optical system;    an alignment optical system for illuminating a light flux for alignment comprised of multiple light fluxes having different wavelengths on a mark for position detection provided on each of said reticle and said wafer;    a first photomultiplier for receiving diffraction light of said light flux for alignment from said mark for position detection of said reticle;    a second photomultiplier for receiving diffraction light of said light flux for alignment from said mark for position detection of said wafer;    a phase difference detector for detecting a phase difference between said reticle and said wafer on the basis of electrical signals converted photoelectrically by said first and second photomultipliers;    an alignment device for aligning said reticle with said wafer on the basis of the phase difference detected by said phase difference detector; and    an optical guide for leading each of the diffraction light from said mark for position detection of said reticle and the diffraction light from said mark for position detection of said wafer to said respective first and second photomultipliers.    
     
     
         14 . An exposure apparatus as claimed in    claim 13   , wherein: 
 the diffraction light from each of said marks for position detection of said reticle and said wafer comprises a light flux of multiple wavelengths; and    the light flux returning from each of said marks for position detection of said reticle and said wafer is led to said photomultiplier through the optical guide different for each wavelength after separation into each wavelength.    
     
     
         15 . An exposure apparatus as claimed in    claim 14   , wherein: 
 each of said multiple optical guides comprises an optical fiber with a propagation efficiency optimized for a wavelength of the light flux as an object of propagation.    
     
     
         16 . An exposure apparatus as claimed in any one of    claims 13    to    15   , wherein: 
 said mark for position detection is a mark of a diffraction grating form arranged by a predetermined pitch in a direction of measurement; and  
 said alignment optical system is an optical system for illuminating mutually coherent multiple light fluxes onto said mark of the diffraction grating form from different directions.  
 
     
     
         17 . An exposure apparatus as claimed in any one of    claims 13    to    16   , wherein: 
 said light flux for alignment comprises a light flux of multiple wavelengths; and  
 said light flux is led to said alignment optical system through an optical guide different for each of the multiple wavelengths constituting the light flux.  
 
     
     
         18 . An exposure apparatus as claimed in    claim 16    or    17   , wherein: 
 said first interference light comprised of multiple diffraction light generating from said mark of the diffraction grating form in a direction parallel to a first direction is led to said first photomultiplier by said optical guide after separation into a light flux of each wavelength; and  
 said second interference light comprised of multiple diffraction light generating from said mark of the diffraction grating form in a direction parallel to a second direction yet different from the first direction is led to said second photomultiplier by said optical guide after separation into a light flux of each wavelength.  
 
     
     
         19 . An exposure apparatus as claimed in    claim 16    or    17   , wherein: 
 said first interference light comprised of multiple diffraction light generating from said mark of the diffraction grating form in a direction parallel to a first direction is led to a position in the vicinity of said first photomultiplier by said optical guide before separation into a light flux of each wavelength; and  
 said second interference light comprised of multiple diffraction light generating from said mark of the diffraction grating form in a direction parallel to a second direction yet different from the first direction is led to a position in the vicinity of said second photomultiplier by said optical guide before separation into a light flux of each wavelength.  
 
     
     
         20 . An exposure apparatus as claimed in    claim 9   , wherein: 
 said light recipient optical system contains a light recipient element for photoelectrically converting the light returning from said mark for alignment; and    said light recipient element is disposed in a position isolated from the main body portion of the exposure apparatus.    
     
     
         21 . A method for detecting a position of a substrate, comprising: 
 illuminating multiple pairs of light for position detection onto a mark formed on the substrate from two different directions;    receiving the light from the mark by a light recipient element;    detecting the position of the substrate on the basis of optical information from said light recipient element; and    leading the multiple pairs of the light for position detection to the substrate through an optical guide.    
     
     
         22 . A method as claimed in    claim 21   , wherein: 
 the light from said mark is led to said light recipient element through a guide.    
     
     
         23 . A method for exposing a mask pattern to a substrate, comprising: 
 illuminating different rays of light for position detection onto a mark formed on said substrate;    receiving the light from the mark by a light recipient element;    detecting the position of the substrate on the basis of optical information from said light recipient element; and    leading the light for position detection to the substrate from outside of a chamber with said substrate disposed therein.