Multilayer Coatings For EUV Mask Substrates

Abstract

Techniques, methods, and structures disclosed in relation to extreme ultraviolet (EUV) lithography in semiconductor processing. In one exemplary implementation, a method may comprise using ion beam deposition to deposit a first multilayer stack of thin films on a substrate to planarize and smooth surface defects on the substrate. The method includes using atomic layer deposition to deposit a second multilayer stack of thin films on the first multilayer stack of thin films. The second multilayer stack of thin films may comprise an extreme ultraviolet reflective multilayer stack. The second multilayer stack of thin films may comprise fewer surface defects than the first multilayer stack of thin films. The method may further comprise processing an extreme ultraviolet mask blank to form an extreme ultraviolet reflective mask.

1 . A method, the method comprising: 
 using ion beam deposition to deposit a first multilayer stack of thin films on a substrate to planarize and smooth surface defects on the substrate; and    using atomic layer deposition to deposit a second multilayer stack of thin films on the first multilayer stack of thin films, the second multilayer stack of thin films comprising an extreme ultraviolet reflective multilayer stack.    
     
     
         2 . The method of  claim 1 , wherein the first multilayer stack of thin films comprises alternating layers of thin film layers, the alternating layers of thin film layers comprise one of Molybdenum and Silicon thin films, Molybdenum and Beryllium thin films, and Molybdenum and Silicon compound thin films, wherein the Silicon compound comprises one of Silicon Nitride and Silicon Dioxide.  
     
     
         3 . The method of  claim 1 , wherein the second multilayer stack of thin films comprises alternating layers of thin film layers, the alternating layers of thin film layers comprise one of Molybdenum and Silicon thin films, Molybdenum and Beryllium thin films, and Molybdenum and Silicon compound thin films, wherein the Silicon compound comprises one of Silicon Nitride and Silicon Dioxide.  
     
     
         4 . The method of  claim 1 , wherein the first multilayer stack of thin films comprises 20 to 40 alternating layers of thin film layers, wherein the alternating layers of thin films comprise a first film and a second film with different optical properties.  
     
     
         5 . The method of  claim 1 , wherein the second multilayer stack of thin films comprises 40 to 60 alternating layers of thin film layers, wherein the alternating layers of thin films comprise a first film and a second film with different optical properties.  
     
     
         6 . The method of  claim 1 , wherein the second multilayer stack of thin films comprises fewer surface defects than the first multilayer stack of thin films.  
     
     
         7 . The method of  claim 1 , further comprising processing an extreme ultraviolet mask blank to form an extreme ultraviolet reflective mask.  
     
     
         8 . The method of  claim 7 , the processing an extreme ultraviolet mask blank to form an extreme ultraviolet reflective mask comprising: 
 depositing a buffer layer on the second multilayer stack of thin films;    depositing an absorber layer on the buffer layer; and    depositing a resist layer on the buffer layer.    
     
     
         9 . The method of  claim 8 , the processing an extreme ultraviolet mask blank to form an extreme ultraviolet reflective mask further comprising: 
 patterning and developing the resist layer;    pattering the absorber layer;    removing the resist layer; and    patterning the buffer layer.