Light reflecting mask, exposure apparatus, and measuring method

Abstract

A light reflecting mask includes a reflecting layer which is provided on a substrate and reflects light, an absorbing layer which is provided on the reflecting layer and absorbs light, a device pattern which is formed in a first region of the absorbing layer, and a reflectance measuring pattern which is formed in a second region of the absorbing layer. The reflectance measuring pattern is a diffraction grating.

1 .- 6 . (canceled) 
     
     
         7 . An exposure apparatus comprising:
 a first light source which emits exposure light;   a holding mechanism which holds a light reflecting mask having a reflectance measuring pattern; and   a first photosensor which detects an intensity of light reflected by the reflectance measuring pattern.   
     
     
         8 . The apparatus according to  claim 7 , wherein the first photosensor detects diffraction light of not lower than first order. 
     
     
         9 . The apparatus according to  claim 7 , wherein
 the light reflecting mask further includes a device pattern, and   the first photosensor is arranged outside a path of the exposure light reflected by the device pattern.   
     
     
         10 . The apparatus according to  claim 9 , further comprising an illumination optical system which illuminates the device pattern and the reflectance measuring pattern with the exposure light. 
     
     
         11 . The apparatus according to  claim 7 , further comprising a second photosensor which detects the intensity of the exposure light before illuminating the reflectance measuring pattern. 
     
     
         12 . The apparatus according to  claim 7 , further comprising a second light source which illuminates the reflectance measuring pattern with measuring light. 
     
     
         13 . The apparatus according to  claim 12 , wherein the first photosensor detects diffraction light of the measuring light. 
     
     
         14 . The apparatus according to  claim 7 , wherein the exposure light is extreme ultraviolet (EUV) light. 
     
     
         15 . A measuring method comprising:
 arranging a light reflecting mask having a device pattern and a reflectance measuring pattern;   illuminating the device pattern and the reflectance measuring pattern with exposure light; and   detecting an intensity of light reflected by the reflectance measuring pattern.   
     
     
         16 . The method according to  claim 15 , wherein detecting the intensity of the light is performed in an exposure process using the device pattern. 
     
     
         17 . The method according to  claim 15 , further comprising arranging a photosensor outside a path of the exposure light reflected by the device pattern,
 wherein the photosensor detects the intensity of the light.   
     
     
         18 . The method according to  claim 17 , wherein the photosensor detects diffraction light of not lower than first order. 
     
     
         19 . The method according to  claim 15 , further comprising detecting the intensity of the exposure light before illuminating the reflectance measuring pattern. 
     
     
         20 . The method according to  claim 19 , further comprising arranging a photosensor outside a path of the exposure light illuminating the reflectance measuring pattern,
 wherein the photosensor detects the intensity of the exposure light.