Method for the post-etch cleaning of multi-level damascene structures having underlying copper metallization

Abstract

A method for the post-etch cleaning of multi-level, damascene structures which minimizes, or substantially prevents, localized corrosion of underlying copper metallization comprises subjecting an intermediate structure in the fabrication of a multi-level, damascene structure, which structure includes an underlying copper metallization layer and an opening etched therein which exposes at least a portion of the underlying copper metallization layer, to an aqueous or acidic wash solution, in an environment substantially shielded from ambient light, to substantially remove any post-etch residues which may be present on the structure. In one embodiment, the aqueous or acidic wash solution has a nonzero static etch rate when applied to both the copper and conventional dielectric materials, e.g., silicon dioxide.

1 . A method for post-etch cleaning of a damascene structure having a barrier layer disposed over at least a portion of a copper metallization layer and a dielectric layer disposed over at least a portion of the barrier layer, comprising: 
 etching at least one opening through a dielectric layer and a barrier layer to expose at least a portion of a copper metallization layer and to form an etched structure; and    subjecting the etched structure to an aqueous solution in an environment wherein the etched structure is substantially shielded from ambient light, wherein the aqueous solution comprises hydrofluoric acid.    
   
   
       2 . The method of  claim 1 , wherein subjecting the etched structure to an aqueous solution in an environment wherein the etched structure is substantially shielded from ambient light comprises removing residues from sidewalls of the at least one opening.  
   
   
       3 . The method of  claim 1 , wherein subjecting the etched structure to an aqueous solution in an environment wherein the etched structure is substantially shielded from ambient light comprises removing copper residues or dielectric material residues from sidewalls of the at least one opening.  
   
   
       4 . The method of  claim 1 , wherein subjecting the etched structure to an aqueous solution in an environment wherein the etched structure is substantially shielded from ambient light comprises removing copper residues or dielectric material residues from sidewalls of the at least one opening at a static etch rate of about 15 Å/minute.  
   
   
       5 . The method of  claim 1 , wherein subjecting the etched structure to an aqueous solution in an environment wherein the etched structure is substantially shielded from ambient light comprises subjecting the etched structure to the aqueous solution for a period of time ranging from about 30 seconds to about 2 minutes.  
   
   
       6 . The method of  claim 1 , further comprising forming a diffusion barrier over the etched structure subsequent to subjecting the etched structure to the aqueous solution while maintaining the etched structure in the environment wherein the etched structure is substantially shielded from ambient light.  
   
   
       7 . The method of  claim 6 , further comprising: 
 forming a bulk copper layer over the diffusion barrier such that the at least one opening is filled therewith; and    planarizing the bulk copper layer to a surface of the dielectric layer.    
   
   
       8 . A method of post-etch cleaning of a damascene structure, comprising: 
 subjecting at least a portion of a copper metallization layer to an aqueous solution in an environment wherein the at least a portion of the copper metallization layer is substantially shielded from ambient light, wherein the aqueous solution comprises hydrofluoric acid.    
   
   
       9 . The method of  claim 8 , wherein subjecting at least a portion of a copper metallization layer to an aqueous solution in an environment wherein the at least a portion of the copper metallization layer is substantially shielded from ambient light comprises subjecting the at least a portion of the copper metallization layer to an aqueous solution that comprises about 7.0% by weight of acetic acid, about 0.4% by weight of nitric acid, and about 0.15% by weight of hydrofluoric acid.  
   
   
       10 . The method of  claim 8 , wherein subjecting at least a portion of a copper metallization layer to an aqueous solution in an environment wherein the at least a portion of the copper metallization layer is substantially shielded from ambient light comprises removing residues from sidewalls of at least one opening through which the at least a portion of the copper metallization layer is exposed.  
   
   
       11 . The method of  claim 8 , wherein subjecting at least a portion of a copper metallization layer to an aqueous solution in an environment wherein the at least a portion of the copper metallization layer is substantially shielded from ambient light comprises removing copper residues or dielectric material residues from sidewalls of at least one opening through which the at least a portion of the copper metallization layer is exposed.  
   
   
       12 . The method of  claim 8 , wherein subjecting at least a portion of a copper metallization layer to an aqueous solution in an environment wherein the at least a portion of the copper metallization layer is substantially shielded from ambient light comprises removing copper residues or dielectric material residues at a static etch rate of about 15 Å/minute from sidewalls of at least one opening through which the at least a portion of the copper metallization layer is exposed.  
   
   
       13 . The method of  claim 8 , wherein subjecting at least a portion of a copper metallization layer to an aqueous solution in an environment wherein the at least a portion of the copper metallization layer is substantially shielded from ambient light comprises subjecting the at least a portion of the copper metallization layer to the aqueous solution for a period of time ranging from about 30 seconds to about 2 minutes.