Exposing mask and production method therefor and exposing method

Abstract

An exposure mask forms a three-dimensional shape in simple structure and obtainable sufficient number of gray scales by exposure. In an exposure mask (M) for use in an exposure apparatus (S), the present invention is provided such that a plurality of pattern blocks constituted by a pair of a light blocking pattern blocking light emitted from the exposure apparatus (S) and a transmissive pattern transmitting the light are continuously arranged while a pitch of the continuous pattern blocks is constant and a ratio of the light blocking pattern to the transmissive pattern is varied gradually.

1 . An exposure mask for use in an exposure apparatus characterized by comprising: 
 a plurality of pattern blocks configured from a pair of a light blocking pattern for blocking illumination light emitted from said exposure apparatus and a transmissive pattern for transmitting said illumination light, said is plurality of pattern blocks being continuously arranged;    wherein a pitch of said continuous pattern blocks is constant and a ratio of said light blocking pattern to said transmissive pattern is varied gradually.    
     
     
         2 . The exposure mask according to  claim 1 , characterized in that: 
 said pitch of said continuous pattern block has a size such that light reaching an image formation plane through said pattern block is only 0th order light.    
     
     
         3 . The exposure mask according to  claim 1 , characterized in that a following equation is satisfied: 
           P<λ/{NA ×(1+σ)} 
       where said pitch of said continuous pattern block is P (converted on the wafer surface), an exposure wavelength of said exposure apparatus is λ, a numerical aperture of said exposure apparatus is NA, and a coherence factor (σ) indicative of a size of a secondary light source.  
     
     
         4 . The exposure mask according to  claim 1 , characterized in that: 
 said pattern block is configured such that said light blocking pattern and said transmissive pattern are formed with straight lines, respectively.    
     
     
         5 . The exposure mask according to  claim 1 , characterized in that: 
 said pattern block is constructed as a through-hole type or an island type by said light blocking pattern and said transmissive pattern.    
     
     
         6 . The exposure mask according to  claim 1 , characterized in that: 
 said pitch of said continuous pattern block is 1/an integer of a size of an element formed by exposure.    
     
     
         7 . The exposure mask according to  claim 1 , characterized in that: 
 said pattern block forms a cylindrical lens by exposure through said pattern block.    
     
     
         8 . The exposure mask according to  claim 1 , characterized in that: 
 said pattern block forms a spherical lens or an aspherical lens by exposure through said pattern block.    
     
     
         9 . The exposure mask according to  claim 1 , characterized in that: 
 said pattern block forms a prism array by exposure through said pattern block.    
     
     
         10 . A design and fabrication method of an exposure mask in which a plurality of pattern blocks constituted by a pair of a light blocking pattern blocking light emitted from an exposure apparatus and a transmissive pattern transmitting said light are continuously arranged, in order to form a three-dimensional shape by irradiating a predetermined amount light to a photosensitive material, is characterized by comprising the steps of: 
 calculating an exposure amount distribution to said photosensitive material from design data of said three-dimensional shape;    calculating a transmittance distribution of said exposure mask based on said exposure amount distribution;    calculating a pitch of said continuous pattern block from optical conditions of said exposure apparatus; and    arranging a plurality of said pattern blocks so as to be respective ratios by calculating a ratio of said light blocking pattern to said transmissive pattern within said pitch of said pattern blocks according to said transmittance distribution.    
     
     
         11 . The fabrication method of an exposure mask according to  claim 10 , characterized in that: 
 in said step of calculating an exposure amount distribution to said photosensitive material from design data of said three-dimensional shape, an effective exposure amount to which a flare amount of an optical system of said exposure apparatus is added is calculated as said exposure amount distribution.    
     
     
         12 . The fabrication method of an exposure mask according to  claim 11 , characterized in that: 
 said flare amount of an optical system of said exposure apparatus is quantified by performing an overexposure with a known pattern of light transmittance and obtaining an amount of exposure by which said overexposure removes remaining resist films.    
     
     
         13 . The exposure mask according to  claim 1 , characterized in that: 
 a first mask constituted by said light blocking pattern and said transmissive pattern linearly provided along one direction and a second mask constituted by said light blocking pattern and said transmissive pattern linearly provided perpendicular to said one direction are provided on a single base material.    
     
     
         14 . An exposure method for a photosensitive material using an exposure mask in which a plurality of pattern blocks configured from a pair of a light blocking pattern for blocking illumination light emitted from an exposure apparatus and a transmissive pattern for transmitting said illumination light, said plurality of pattern blocks being continuously arranged; and a pitch of said continuous pattern block is constant and a ratio of said light blocking pattern to said transmissive pattern is varied gradually; characterized by comprising the steps of: 
 first exposing for said photosensitive material using an exposure mask having a pattern block in which said light blocking pattern and said transmissive pattern linearly provided along one direction;    second exposing for said photosensitive material using an exposure mask having a pattern block in which said light blocking pattern and said transmissive pattern are linearly provided perpendicular to said one direction so as to superpose a portion where said first exposure performed.    
     
     
         15 . The exposure method according to  claim 14 , characterized in that: 
 after said first exposure is performed, said exposure mask used in said first exposure is rotated by 90° and said second exposure is performed.    
     
     
         16 . The exposure method according to  claim 14 , characterized in that: 
 an exposure mask for performing said first exposure and an exposure mask for performing said second exposure are provided on a single base material, after said first exposure performed, said second exposure is performed by selectively moving exposure position of said base material.    
     
     
         17 . The exposure mask according to  claim 1 , characterized in that: 
 a ratio of said light blocking pattern to said transmissive pattern is continuously varied according to transmittance of illumination light at said pattern block.    
     
     
         18 . The exposure mask according to  claim 5 , characterized in that: 
 said pattern block is arranged in rectangular form.    
     
     
         19 . The exposure mask according to  claim 1 , characterized in that: 
 a periphery pattern is provided at periphery of said continuous pattern block, as said periphery pattern, a light blocking pattern and a transmissive pattern having a same ratio of a light blocking pattern to transmissive pattern constituting a pattern block at outermost periphery or edge of said continuous pattern block is arranged.    
     
     
         20 . The fabrication method of an exposure mask according to  claim 10 , characterized in that: 
 in said step of calculating an exposure amount distribution to said photosensitive material from design data of said three-dimensional shape, said exposure amount distribution takes into account an etching conversion difference during etching at a later step.    
     
     
         21 . The fabrication method of an exposure mask according to  claim 10 , characterized in that: 
 said etching conversion differences are formed from values depending on a height of said photosensitive material before etching and being represented in a function or a table.