Resists for lithography

Abstract

New routes involving multi-step reversible photo-chemical reactions using two-step techniques to provide non-linear resist for lithography are described in this disclosure. They may provide exposure quadratically dependant on the intensity of the light. Several specific examples, including but not limited to using nanocrystals, are also described. Combined with double patterning, these approaches may create sub-diffraction limit feature density.

We claim: 
     
         1 . A resist comprising:
 at least one matrix material;   a photoactive material; and   an acid generator attached to said photoactive material,   said photoactive material undergoing at least one plural-step reaction comprising absorption of at least one photon to generate a further photoactive material, said further photoactive material at least in part reversing to the first-mentioned photoactive material unless said further photoactive material absorbs at least another photon to activate said acid generator to change the solubility of said resist in response to light, wherein said solubility change is non-linearly dependent on the intensity of the light.   
     
     
         2 . The resist of  claim 1  wherein at least one of the first-mentioned and further photoactive materials comprises nanocrystals. 
     
     
         3 . The resist of  claim 1  wherein at least one of the first-mentioned and further photoactive materials comprises a semiconductor. 
     
     
         4 . The resist of  claim 1  wherein at least one of the first-mentioned and further photoactive materials comprises at least one organic molecule. 
     
     
         5 . The resist of  claim 1  wherein at least one of the first-mentioned and further photoactive materials comprises at least one inorganic molecule. 
     
     
         6 . The resist of  claim 1  wherein the acid generator forms an acid in a manner that is quadratically dependent on the intensity of the light. 
     
     
         7 . The resist of  claim 1  wherein said matrix material comprises a polymer or a molecular glass. 
     
     
         8 . The resist of  claim 1  wherein said resist further comprises additives to improve resolution and line edge roughness. 
     
     
         9 . The resist of  claim 8  wherein said additives comprise bases to quench photo-generated acids generated by the acid generator. 
     
     
         10 . The resist of  claim 1  wherein said solubility changes in the presence of a developer. 
     
     
         11 . The resist of  claim 1  further including responding to plural light illuminations separated in time. 
     
     
         12 . The resist of  claim 1  wherein said resist is configured for use in immersion lithography. 
     
     
         13 . A method of exposing a resist comprising:
 illuminating at least part of said resist with a light source;   inducing in said resist in a manner that is quadratically dependent on the intensity of said illuminating light,   at least one first photoactive material, wherein an acid generator is attached to said first photoactive material, said first photoactive material, in use, undergoing at least one plural-step reaction comprising, absorption of at least one photon to generate at least one second photoactive material, said second photoactive material at least in part reversing to the first photoactive material unless said second photoactive material absorbs at least another photon to activate said acid generator which ultimately leads to a change in solubility of said resist.   
     
     
         14 . The method of  claim 13  wherein said first photoactive material comprises nanocrystal photosensitive material. 
     
     
         15 . The method of  claim 13  wherein said first photoactive material comprises semiconductor photosensitive material. 
     
     
         16 . The method of  claim 13  wherein said first photoactive material comprises at least one organic molecule photosensitive material. 
     
     
         17 . The method of  claim 13  wherein said first photoactive material comprises at least one inorganic molecule photosensitive material. 
     
     
         18 . The method of  claim 13  wherein said illuminating comprises illuminating with at least one of the following light wavelengths: 157 nm, 193 nm, 248 nm, 257 nm, 198 nm, 121 nm and 365 nm. 
     
     
         19 . The method of  claim 13  wherein said illuminating comprises illuminating with 13.4 nm light. 
     
     
         20 . The method of  claim 16  wherein said illuminating comprises illuminating said resist multiple times separated by waiting times therebetween.