Semiconductor multilevel interconnect structure

Abstract

A method of fabricating a semiconductor multilevel interconnect structure employs a dual hardmask technique in a dual damascene process. The method includes using amorphous carbon as a first hardmask layer capable of being etched by a second etch process, and a second hardmask layer capable of being etched by a first etch process, as a dual hardmask. By virtue of the selective etch chemistry employed with the dual hardmask, the method affords flexibility unattainable with conventional processes. The via is never in contact with the photoresist, thus eliminating residual photoresist at the trench/via edge and the potential “poisoning” of the intermetal dielectric layer. Since trench/via imaging is completed before further etching, any patterning misalignments can be easily reworked. Because the amorphous carbon layer and the second hardmask layer are used as the dual hardmask, the photoresist can be made thinner and thus optimized for the best imaging performance.

1 - 42 . (canceled)  
   
   
       43 . A structure for use in fabricating a dual damascene opening, said structure comprising: 
 a first layer comprising a metal portion;    a first protective layer on said first layer;    an intermetal dielectric layer on said first protective layer;    a second protective layer on said second intermetal dielectric layer;    an amorphous carbon layer as a first hardmask layer on said second protective layer; and    a second hardmask layer on said amorphous carbon layer.    
   
   
       44 . A structure according to  claim 43 , wherein said first protective layer comprises a material selected from the group consisting of silicon nitrides, silicon carbo-nitrides, and silicon carbides.  
   
   
       45 . A structure according to  claim 43 , wherein said second protective layer comprises a material selected from the group consisting of silicon nitrides, silicon carbides, and silicon carbo-nitrides.  
   
   
       46 . A structure according to  claim 43 , wherein said second hardmask layer comprises a material selected from the group consisting of silicon oxides, silicon nitrides, silicon carbo-nitrides, silicon carbides, and titanium nitrides.  
   
   
       47 . A structure according to  claim 43 , wherein said second protective layer is a dielectric antireflective coating.  
   
   
       48 . A structure according to  claim 43 , wherein said second hardmask layer is a dielectric antireflective coating.  
   
   
       49 . A structure according to  claim 43 , wherein said metal portion is Cu.  
   
   
       50 . A structure for use in fabricating a dual damascene opening, said structure comprising: 
 an amorphous carbon layer as a first hardmask layer;    a second hardmask layer on said amorphous carbon layer; and    a photoresist layer on said second hardmask layer, said photoresist layer having a thickness of from 1000 to 6000 Å.