Photomask, exposure control method and method of manufacturing a semiconductor device

Abstract

A photomask transferring a light shield film pattern formed on a transparent substrate by a projection exposure apparatus, comprising a circuit pattern for transferring a predetermined pattern to a resist film, and an exposure monitor mark, the exposure monitor mark being formed in a manner that blocks having a predetermined width p, which are not resolved by the projection exposure apparatus, are intermittently or continuously arrayed along one direction, light shield and transmission portions are arrayed along one direction in each of the blocks, the blocks are arrayed so that a dimension ratio of the light shield and transmission portions of the blocks simply changes and the phase difference of exposure light passing through adjacent light transmission portions is approximately 180°.

1 . A photomask for transferring a light shield film pattern formed on a transparent substrate by a projection exposure apparatus onto a resist film formed on a wafer, comprising: 
 a mask pattern for the target pattern for transferring a predetermined pattern to a resist film; and    a mask pattern for the exposure monitor mark,    the mask pattern for the exposure monitor mark being formed in a manner that blocks having a predetermined width p, which are not resolved by the projection exposure apparatus, are intermittently or continuously arrayed along one direction, light shield and transmission portions are arrayed along one direction in each of the blocks, the blocks are arrayed so that a dimension ratio of the light shield and transmission portions of the blocks simply changes and a phase difference of exposure light passing through adjacent light transmission portions is approximately 180°.    
   
   
       2 . The photomask according to  claim 1 , wherein an optical film is formed on one of adjacent light transmission portions, and the thickness of the optical film is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       3 . The photomask according to  claim 1 , wherein the transparent substrate of one of adjacent light transmission portions is engraved, and the engraved rate of the transparent substrate is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       4 . The photomask according to  claim 1 , wherein when a wavelength of the exposure light of the projection exposure apparatus is set as λ, a numerical aperture of the substrate side of the projection exposure apparatus is set as NA, and a width of said one direction of a projection image corresponding to the block in projecting the mask pattern for the exposure monitor mark onto the resist film using the projection exposure apparatus when is set as P, the following relation is given: 
         P≦λ/ 2 NA.   
   
   
       5 . An exposure control method comprising: 
 preparing a projection exposure apparatus;    preparing a photomask which including a transparent substrate, and a light shield film which having patterns to be transferred to a resist film formed on a wafer by the projection exposure apparatus formed on the transparent substrate, the patterns including, a mask pattern for the target pattern to form a latent image predetermined pattern to the resist film, and a mask pattern for the exposure monitor mark to form an exposure monitor mark whose dimension changes in accordance with exposure to the resist film, the mask pattern for the exposure monitor mark being formed in a manner that blocks having a predetermined width p, which are not resolved by the projection exposure apparatus, are intermittently or continuously arrayed along one direction, light shield and transmission portions are arrayed along one direction in each of the blocks, the blocks are arrayed so that a dimension ratio of the light shield and transmission portions of the blocks simply changes and a phase difference of exposure light passing through adjacent light transmission portions is approximately 180°;    transferring the mask pattern for the exposure monitor mark to the resist film using the projection exposure apparatus to form a latent image of the exposure monitor mark on the resist film;    measuring a dimension of an exposure monitor mark obtained by developing the latent image of the exposure monitor mark and/or the resist film;    calculating a difference between an optimum exposure value when transferring the pattern formed on the photomask to the resist film and an predetermined exposure value preset in the projection exposure apparatus based on the measurement result; and    changing the predetermined exposure value in accordance with the calculated difference.    
   
   
       6 . The method according to  claim 5 , wherein an optical film is formed on one of adjacent light transmission portions, and the thickness of the optical film is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       7 . The method according to  claim 5 , wherein the transparent substrate of one of adjacent light transmission portions is engraved, and the engraved rate of the transparent substrate is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       8 . The method according to  claim 5 , wherein when a wavelength of the exposure light of the projection exposure apparatus is set as λ, a numerical aperture of the substrate side of the projection exposure apparatus is set as NA, and a width of said one direction of a projection image corresponding to the block in projecting the mask pattern for the exposure monitor mark onto the resist film using the projection exposure apparatus when is set as P, the following relation is given: 
         P≦λ/ 2 NA.   
   
   
       9 . A method of manufacturing a semiconductor device, comprising: 
 preparing a projection exposure apparatus;    preparing a photomask which including a transparent substrate and, and a light shield film which having patterns to be transferred to a resist film formed on a wafer by the projection exposure apparatus formed on the transparent substrate, the patterns including, a mask pattern for circuit pattern to form a latent image of a predetermined circuit pattern to a resist film; and a mask pattern for the exposure monitor mark to form a latent image of an exposure monitor mark whose dimension changes in accordance with exposure to the resist film, the mask pattern for the exposure monitor mark being formed in a manner that blocks having a predetermined width p, which are not resolved by the projection exposure apparatus, are intermittently or continuously arrayed along one direction, light shield and transmission portions are arrayed along one direction in each of the blocks, the blocks are arrayed so that a dimension ratio of the light shield and transmission portions of the blocks simply changes and a phase difference of exposure light passing through adjacent light transmission portions is approximately 180°;    transferring the mask pattern for the exposure monitor mark to the resist film using the projection exposure apparatus to form a latent image of the exposure monitor mark on the resist film;    measuring a dimension of an exposure monitor mark obtained by developing the latent image of the exposure monitor mark and/or the resist film;    calculating a difference between an optimum exposure value when transferring the pattern formed on the photomask to the resist film and an predetermined exposure value preset in the projection exposure apparatus based on the measurement result; and    changing at least one of exposure of the projection exposure apparatus, heat treatment time in a heat process after exposure, heat treatment temperature in the heat process, development time in a development process, developer temperature or developer concentration in accordance with the calculated difference.    
   
   
       10 . The method according to  claim 9 , wherein an optical film is formed on one of adjacent light transmission portions, and the thickness of the optical film is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       11 . The method according to  claim 9 , wherein the transparent substrate of one of adjacent light transmission portions is engraved, and the engraved rate of the transparent substrate is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       12 . The method according to  claim 9 , wherein when a wavelength of the exposure light of the projection exposure apparatus is set as λ, a numerical aperture of the substrate side of the projection exposure apparatus is set as NA, and a width of said one direction of a projection image corresponding to the block in projecting the mask pattern for the exposure monitor mark onto the resist film using the projection exposure apparatus when is set as P, the following relation is given: 
         P≦λ/ 2 NA.   
   
   
       13 . A method of manufacturing a semiconductor device, comprising: 
 preparing a projection exposure apparatus;    preparing a photomask which including a transparent substrate and, and a light shield film which having patterns to be transferred to a resist film formed on a wafer by the projection exposure apparatus formed on the transparent substrate, the patterns including, a mask pattern for circuit pattern to form a latent image of a predetermined circuit pattern to a resist film; and first and second mask patterns for the exposure monitor mark to form each latent image of exposure monitor mark whose dimension changes in accordance with exposure to the resist film, the first mask pattern for the exposure monitor mark being formed in a manner that first blocks having a predetermined width p, which are not resolved by the projection exposure apparatus, are intermittently or continuously arrayed along one direction, first light shield and transmission portions are arrayed along one direction in each of the first blocks, the first blocks are arrayed so that a dimension ratio of the first light shield and transmission portions of the first blocks simply changes and a phase difference of exposure light passing through adjacent first light transmission portions is approximately 180°, the second mask pattern for the exposure monitor mark being formed in a manner that second blocks having a predetermined width p, which are not resolved by the projection exposure apparatus, are intermittently or continuously arrayed along one direction, second light shield and transmission portions are arrayed along one direction in each of the second blocks, the second blocks are arrayed so that a dimension ratio of the second light shield and transmission portions of the second blocks simply changes and a phase difference of exposure light passing through adjacent second light transmission portions is approximately 0°;    transferring the first and second mask patterns for the exposure monitor mark to the resist film using the projection exposure apparatus to form each latent image of the first and second exposure monitor marks on the resist film;    measuring each dimension of the first and second exposure monitor marks obtained by developing the latent image of the first and second exposure monitor mark and/or the resist film;    calculating a first effective exposure based on the dimension of the first exposure monitor mark;    calculating a second effective exposure based on the dimension of the second exposure monitor mark; and    changing at least one of deposit condition of a front-end formed under the resist film or resist film coating condition if the first and second effective exposure have a relation different from each other.    
   
   
       14 . The method according to  claim 13 , wherein an optical film is formed on one of adjacent light transmission portions, and the thickness of the optical film is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       15 . The method according to  claim 13 , wherein the transparent substrate of one of adjacent light transmission portions is engraved, and the engraved rate of the transparent substrate is adjusted so that a phase difference between an exposure light passing through one light transmission portion and an exposure light passing through the other light transmission portion becomes 180°.  
   
   
       16 . The method according to  claim 13 , wherein when a wavelength of the exposure light of the projection exposure apparatus is set as λ, a numerical aperture of the substrate side of the projection exposure apparatus is set as NA, and a width of said one direction of a projection image corresponding to the block in projecting the mask pattern for the exposure monitor mark onto the resist film using the projection exposure apparatus when is set as P 1 , the following relation is given: 
         P   1 ≦λ/2 NA.