Laser device and exposure device using the same

Abstract

In a laser module, a laser beam which is emitted from a laser element is focused by a condensing optical system and caused to enter an incidence end of an optical fiber. A laser device is provided with a plurality of these laser modules. Emission end portions of the optical fibers are bundled to form a laser emission portion. A thickness of cladding h of each optical fiber is set to a value calculated in accordance with the following equation: cladding thickness ⁢   ⁢ h ≤ ( emission ⁢   ⁢ light ⁢   ⁢ amount of ⁢   ⁢ one ⁢   ⁢ laser ⁢   ⁢ module ⁢   ⁢ W required intensity ⁢   ⁢ C × packing ratio ⁢   ⁢ P - core diameter ⁢   ⁢ t ) ÷ 2 As a result, it is possible to emit a laser-beam with a high intensity that is required for functionality as a laser light source, for the purpose of raising resolution of an exposure apparatus.

1 . A laser device comprising: 
 laser elements;    optical fibers each including cladding surrounding a core, and including an incidence end;    laser modules including condensing optical systems which focus laser beams emitted from the laser elements and cause the laser beams to enter through incidence ends of the optical fibers;    a plurality of connective emission end portions at each of which a predetermined number of the optical fibers, which respectively lead out from the laser modules, are bundled to form a fiber bundle;    a plurality of multiplex optical fibers, an incidence end of each of which is connected at one of the connective emission end portions, the multiplex optical fiber including a core with a diameter corresponding to an area which exceeds an area of the bundle that corresponds to a region containing the cores of the plurality of bundled optical fibers, such that laser beams that are emitted through the connective emission end portion are multiplexed, and the multiplex optical fiber including a numerical aperture equal to or greater than a numerical aperture of the optical fibers that lead out from the laser modules; and    a laser emission portion at which emission end portions of the plurality of multiplex optical fibers are bundled to form a fiber bundle.    
     
     
         2 . The laser device of  claim 1 , further comprising a focusing lens and a housing at each connective emission end portion, 
 the housing including a structure such that a light beam that is emitted through the connective emission end portion, at which the plurality of optical fibers forms the first fiber bundle, is focused by the focusing lens and caused to enter the core of the multiplex optical fiber, and    the housing being structured in the form of a closed-structure container which encloses, all together, the connective emission end portion, the focusing lens and an incidence end portion of the multiplex optical fiber, a sealed atmosphere which includes an inactive gas being charged into the housing.    
     
     
         3 . The laser device of  claim 1 , further comprising, at each connective emission end portion: 
 a first transparent member, which is disposed at an emission end face of the connective emission end portion, at which the plurality of optical fibers form the first fiber bundle, for preventing adherence of contaminants and deterioration of laser characteristics;    a second transparent member, which is disposed at a face of the incidence end of the multiplex optical fiber for preventing adherence of contaminants and deterioration of laser characteristics; and    a focusing lens which is disposed between the first transparent member and the second transparent member such that a light beam which, after being emitted from the emission end face of the connective emission end portion, has passed through the first transparent member passes through the second transparent member and enters the core of the multiplex optical fiber.    
     
     
         4 . The laser device of  claim 1 , wherein an arrangement of the bundled emission end portions is determined on the basis of shapes of beam spots that are to be projected at an object of exposure.  
     
     
         5 . The laser device of  claim 1 , wherein the optical fibers that lead out from the laser modules each comprise one selected from the group consisting of step index-type optical fibers, graded index-type optical fibers and multiplex-type optical fibers.  
     
     
         6 . The laser device of  claim 1 , wherein a cladding diameter of the optical fibers that lead out from the laser modules is between 10 μm and 80 μm.  
     
     
         7 . The laser device of  claim 1 , wherein a cladding diameter of the optical fibers that lead out from the laser modules is between 10 μm and 60 μm.  
     
     
         8 . The laser device of  claim 1 , wherein a cladding diameter of the optical fibers that lead out from the laser modules is between 10 μm and 40 μm.  
     
     
         9 . A laser device comprising: 
 a plurality of laser modules, each including 
 at least one laser element,  
 an optical fiber including cladding surrounding a core, and including an incidence end, and  
 a condensing optical system which focuses a laser beam emitted from the at least one laser element and causes the laser beam to enter through the incidence end of the optical fiber;  
   a plurality of connective emission end portions, at each of which the optical fibers that lead out from a predetermined number of the laser modules are bundled to form a first fiber bundle;    a plurality of multiplex optical fibers each including an incidence end and an emission end portion, the incidence end being connected at one of the connective emission end portions, the multiplex optical fiber including a core with a diameter corresponding to an area which encompasses an area that corresponds to the cores of the bundled optical fibers and the multiplex optical fiber including a numerical aperture equal to or greater than a numerical aperture of the bundled optical fibers, such that laser beams that are emitted through the connective emission end portion are multiplexed; and    a laser emission portion at which the emission end portions of the plurality of multiplex optical fibers are bundled to form a second fiber bundle.    
     
     
         10 . An exposure device comprising: 
 a laser device which emits a light beam for exposure, wherein the laser device comprises: 
 laser elements;  
 optical fibers each including cladding surrounding a core, and including an incidence end and an emission end portion; and  
 a laser emission portion at which emission end portions of a plurality of the optical fibers are arranged in the form of a bundle and integrated for emitting a single emission beam, the laser emission portion being provided with a plurality of laser modules that include condensing optical systems which focus laser beams emitted from the laser elements and cause the laser beams to enter through incidence ends of the optical fibers, wherein a thickness h of the cladding of each of the plurality of optical fibers is set to a value calculated in accordance with the following equation:  
               cladding             thickness   ⁢           ⁢   h           ≤       (                 emission   ⁢           ⁢   light   ⁢           ⁢   amount               of   ⁢           ⁢   one   ⁢           ⁢   laser   ⁢           ⁢   module   ⁢           ⁢   W                   required             intensity   ⁢           ⁢   C           ×         packing             ratio   ⁢           ⁢   P                 -         core             diameter   ⁢           ⁢   t             )     ÷   2           
   a light modulation device at which a plurality of modulation elements, which respectively change light modulation states thereof, the spatial light modulation device being for modulating the light beam, which is emitted from the laser device and incident at the plurality of modulation elements, at each of the modulation elements;    a microlens array at which a plurality of microlenses are arranged with a pitch corresponding to the plurality of modulation elements, the microlens array being for condensing light beams, which have been modulated by the modulation elements, at the respective microlenses; and    a focusing optical system for focusing the light beams which have been condensed by the microlens array onto a surface to be exposed.    
     
     
         11 . An exposure device comprising: 
 a laser device which emits a light beam for exposure, wherein the laser device comprises: 
 laser elements;  
 optical fibers each including cladding surrounding a core, and including an incidence end;  
 laser modules including condensing optical systems which focus laser beams emitted from the laser elements and cause the laser beams to enter through incidence ends of the optical fibers;  
 a plurality of connective emission end portions at each of which a predetermined number of the optical fibers, which respectively lead out from the laser modules, are bundled to form a fiber bundle;  
 a plurality of multiplex optical fibers, an incidence end of each of which is connected at one of the connective emission end portions, the multiplex optical fiber including a core with a diameter corresponding to an area which exceeds an area of the bundle that corresponds to a region containing the cores of the plurality of bundled optical fibers, such that laser beams that are emitted through the connective emission end portion are multiplexed, and the multiplex optical fiber including a numerical aperture equal to or greater than a numerical aperture of the optical fibers that lead out from the laser modules; and  
 a laser emission portion at which emission end portions of the plurality of multiplex optical fibers are bundled to form a fiber bundle;  
   a light modulation device at which a plurality of modulation elements, which respectively change light modulation states thereof, the spatial light modulation device being for modulating the light beam, which is emitted from the laser device and incident at the plurality of modulation elements, at each of the modulation elements;    a microlens array at which a plurality of microlenses are arranged with a pitch corresponding to the plurality of modulation elements, the microlens array being for condensing light beams, which have been modulated by the modulation elements, at the respective microlenses; and    a focusing optical system for focusing the light beams which have been condensed by the microlens array onto a surface to be exposed.    
     
     
         12 . The exposure device of  claim 11 , wherein the laser device further comprising a focusing lens and a housing at each connective emission end portion, 
 the housing including a structure such that a light beam that is emitted through the connective emission end portion, at which the plurality of optical fibers forms the first fiber bundle, is focused by the focusing lens and caused to enter the core of the multiplex optical fiber, and    the housing being structured in the form of a closed-structure container which encloses, all together, the connective emission end portion, the focusing lens and an incidence end portion of the multiplex optical fiber, a sealed atmosphere which includes an inactive gas being charged into the housing.