Acid copper electroplating bath and method for electroplating low internal stress and good ductiility copper deposits

Abstract

Acid copper electroplating baths provide improved low internal stress copper deposits with good ductility. The acid copper electroplating baths include one or more branched polyalkylenimines and one or more accelerators. The acid copper electroplating baths may be used to electroplate thin films on relatively thin substrates to provide thin film copper deposits having low internal stress and high ductility.

What is claimed is: 
     
         1 . An acid copper electroplating bath comprising one or more sources of copper ions, an electrolyte, one or more branched polyalkylenimines, one or more accelerators and one or more suppressors. 
     
     
         2 . The acid copper electroplating bath of  claim 1 , wherein the one or more branched polyaklyleneimines have a formula: 
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , R 3 , R 4  and R 5  may be hydrogen or a moiety having a general formula: 
       
       
         
           
           
               
               
           
         
         where R 6  and R 7  are the same or different and are hydrogen or a moiety having a general formula: 
       
       
         
           
           
               
               
           
         
         with the proviso that at least one of R 1 , R 2 , R 3 , R 4  and R 5  is the moiety having formula (II) and n, p, q, r, s, t and u may be the same or different and are integers of 2 to 6 and m is an integer of 2 or greater. 
       
     
     
         3 . The acid copper electroplating bath of  claim 2 , wherein the one or more branched polyalkylenimines are compounds having formula: 
       
         
           
           
               
               
           
         
         wherein m is an integer of 2 or greater. 
       
     
     
         4 . The acid copper electroplating bath of  claim 1 , wherein the one or more branched polyalkylenimines are dendrimers. 
     
     
         5 . The acid copper electroplating bath of  claim 1 , wherein the one or more accelerators are chosen from 3-mercapto-1-propane sulfonic acid, ethylenedithiodipropyl sulfonic acid, bis-(ω-sulfobutyl)-disulfide, methyl-(ω-sulfopropyl)-disulfide, N,N-dimethyldithiocarbamic acid (3-sulfopropyl) ester, (O-ethyldithiocarbonato)-S-(3-sulfopropyl)-ester, 3-[(amino-iminomethyl)-thiol]-1-propanesulfonic acid, 3-(2-benzylthiazolylthio)-1-propanesulfonic acid, bis-(sulfopropyl)-disulfide and alkali metal salts thereof. 
     
     
         6 . The acid copper electroplating bath of  claim 5 , wherein the one or more accelerators are chosen from (O-ethyldithiocarbonato)-S-(3-sulfopropyl)-ester, 3-mercapto-1-propane sulfonic acid and alkali salts thereof. 
     
     
         7 . A method comprises:
 a) contacting a substrate with a copper electroplating bath comprising one or more sources of copper ions, an electrolyte, one or more branched polyalkylenimines, one or more accelerators and one or more suppressors; and   b) electroplating low internal stress high ductility copper on the substrate.   
     
     
         8 . The method of  claim 7 , wherein the one or more branched polyalkylenimines have a formula: 
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , R 3 , R 4  and R 5  may be hydrogen or a moiety having a general formula: 
       
       
         
           
           
               
               
           
         
         where R 6  and R 7  are the same or different and are hydrogen or a moiety having a general formula: 
       
       
         
           
           
               
               
           
         
         with the proviso that at least one of R 1 , R 2 , R 3 , R 4  and R 5  is the moiety having formula (II) and n, p, q, r, s, t and u are the same or different and are integers of 2 to 6 and m is an integer of 2 or greater. 
       
     
     
         9 . The method of  claim 7 , wherein the one or more accelerators are chosen from 3-mercaptopropane-1-sulfonic acid, ethylenedithiodipropyl sulfonic acid, bis-(ω-sulfobutyl)-disulfide, methyl-(ω-sulfopropyl)-disulfide, N,N-dimethyldithiocarbamic acid (3-sulfopropyl) ester, (O-ethyldithiocarbonato)-S-(3-sulfopropyl)-ester, 3-[(amino-iminomethyl)-thiol]-1-propanesulfonic acid, 3-(2-benzylthiazolylthio)-1-propanesulfonic acid, bis-(sulfopropyl)-disulfide and alkali metal salts thereof.