Enhanced lithographic resolution through double exposure

Abstract

A system and method for enhancing the image resolution in a lithographic system, is presented herein. The invention comprises decomposing a reticle pattern into at least two constituent sub-patterns that are capable of being optically resolved by the lithographic system, coating a substrate with a pre-specified photoresist layer, and exposing a first of the at least two constituent sub-patterns by directing a projection beam through the first sub-pattern such that the lithographic system produces a first sub-pattern image onto the pre-specified photoresist layer of the substrate. The invention further comprises processing the exposed substrate, exposing a second of the at least two constituent sub-patterns by directing the projection beam through the second sub-pattern such that the lithographic system produces a second sub-pattern image onto the pre-specified photoresist layer of the substrate, and then combining the first and second sub-pattern images to produce a desired pattern on the substrate.

1 . A method of enhancing the image resolution in a lithographic system, comprising: 
 decomposing a pattern into at least two constituent sub-patterns;    coating a substrate with a pre-specified photoresist layer, said pre-specified photoresist layer having reduced memory reaction characteristics;    exposing a first of said at least two constituent sub-patterns by directing a projection beam onto said first sub-pattern such that said lithographic system produces a first sub-pattern image onto said pre-specified photoresist layer of said substrate;    processing said exposed substrate;    exposing a second of said at least two constituent sub-patterns by directing said projection beam onto said second sub-pattern such that said lithographic system produces a second sub-pattern image onto said pre-specified photoresist layer of said substrate,    wherein said exposing results in a combination of said first and second sub-pattern images to produce a desired pattern on said substrate.    
   
   
       2 . The method of  claim 1 , wherein said lithographic system is capable of optically resolving pattern features that correspond to a half-pitch lower limit k 1  greater than 0.25 and said desired pattern includes features that correspond to a half-pitch lower limit k 1 , less than or equal to 0.25.  
   
   
       3 . The method of  claim 1 , wherein said processing includes, 
 baking said substrate having said first sub-pattern image on said photoresist layer, and    shifting said substrate, in said lithographic system, by a certain distance, in order to interleave said second sub-pattern image with said first sub-pattern image.    
   
   
       4 . The method of  claim 3 , further including applying a developer solution to said substrate.  
   
   
       5 . The method of  claim 3 , wherein said processing is optimized by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k 1  less than or equal to 0.25.  
   
   
       6 . The method of  claim 1 , wherein said pre-specified photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.  
   
   
       7 . The method of  claim 3 , wherein said processing further includes, 
 applying a developer solution to said substrate, and    shifting said substrate, in said lithographic system, by a certain distance, in order to combine said second sub-pattern image with said first sub-pattern image.    
   
   
       8 . The method of  claim 7 , further including baking said substrate having said second sub-pattern image and a developed first sub-pattern image on said photoresist layer.  
   
   
       9 . The method of  claim 8 , wherein said processing is optimized by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k 1  less than or equal to 0.25.  
   
   
       10 . The method of  claim 9 , wherein said pre-specified photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.  
   
   
       11 . The method of  claim 3 , further comprising shifting said substrate before exposing the second of said at least two constituent sub-patterns, in said lithographic system, by a certain distance, in order to interleave said second sub-pattern image with said first sub-pattern image.  
   
   
       12 . An enhanced image resolution lithographic system, comprising: 
 a coating station configured to apply a photoresist layer onto a substrate, said photoresist layer configured to exhibit reduced memory reaction characteristics;    an exposure apparatus to expose a pattern onto said substrate; and    a processing station configured to process a substrate exposed by said exposure apparatus,    wherein said pattern is decomposed into at least two constituent sub-patterns that can be optically resolved by said exposure apparatus,    wherein a first of said at least two constituent sub-patterns is exposed onto said substrate by said exposure apparatus to produce a first sub-pattern image onto said photoresist layer of said substrate and said exposed substrate is processed by said processing station, and    wherein a second of said at least two constituent sub-patterns is exposed onto said substrate by said exposure apparatus to produce a second sub-pattern image onto said photoresist layer of said substrate and said first and second sub-pattern images are combined to produce a desired pattern.    
   
   
       13 . The system of  claim 12 , wherein said exposure apparatus is capable of optically resolving pattern features that correspond to a half-pitch lower limit k 1  greater than 0.25 and said desired pattern includes features that correspond to a half-pitch lower limit k 1  less than or equal to 0.25.  
   
   
       14 . The system of  claim 12 , wherein said processing station includes a baking station configured to bake said substrate having said first sub-pattern image on said photoresist layer.  
   
   
       15 . The system of  claim 14 , configured to shift said substrate by a certain distance, in order to combine said second sub-pattern image with said first sub-pattern image.  
   
   
       16 . The system of  claim 14 , configured to apply a developer solution to said substrate.  
   
   
       17 . The system of  claim 14 , configured to optimize attributes of a baking of said substrate by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k 1  less than or equal to 0.25.  
   
   
       18 . The system of  claim 12 , wherein said photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.  
   
   
       19 . The system of  claim 12 , wherein said processing station further includes: 
 a baking station configured to bake said substrate having said first sub-pattern image on said photoresist layer, and    a developer station to apply developer solution to said substrate.    
   
   
       20 . The system of  claim 19 , configured to shift said substrate by a certain distance, in order to combine said second sub-pattern image with said first sub-pattern image.  
   
   
       21 . The system of  claim 20 , further configured to bake said substrate having said second sub-pattern image and a developed first sub-pattern image on said photoresist layer.  
   
   
       22 . The system of  claim 21 , configured to optimize attributes of a baking of said substrate by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k 1  less than or equal to 0.25.  
   
   
       23 . The system of  claim 22 , wherein said photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.