Endpoint detection and novel chemicals in copper stripping

Abstract

An endpoint detection system for copper stripping using a colorimetric analysis of the change in concentration of a component is described, Wet copper stripping chemicals are used to strip copper from a wafer whereby an eluent is produced. The eluent is continuously analyzed by colorimetric analysis for the presence of copper. The copper stripping process is stopped when the presence of copper is no longer detected. Also novel compounds or chemicals for use in an endpoint detection system for copper stripping using a colorimetric analysis of the change in concentration of the novel compounds or chemicals are described. A composition of matter that serves as an indicator of the presence of copper by colorimetric analysis comprises: 1) Fast Sulphon Black F indicator and an ammonium ion-containing solution or 2) a complexing agent, comprising a diamine, an amine macrocycle, or a monoamine.

What is claimed is:  
     
         1 . A method of copper stripping in the fabrication of an integrated circuit comprising: 
 stripping copper using wet copper stripping chemicals whereby an eluent is produced;    continuously analyzing said eluent for the presence of copper; and    stopping said copper stripping process when said presence of copper is no longer detected.    
     
     
         2 . The method according to  claim 1  where said step of continuously analyzing said eluent is performed by a colorimeter.  
     
     
         3 . The method according to  claim 1  where said step of continuously analyzing said eluent is performed by a spectrophotometer.  
     
     
         4 . The method according to  claim 1  wherein said presence of said copper is detected by a reaction of said copper with an indicator added to said wet stripping chemicals.  
     
     
         5 . The method according to  claim 4  where said indicator comprises Fast Sulphon Black F indicator and an ammonium ion-containing solution.  
     
     
         6 . The method according to  claim 5  wherein said ammonium ion-containing solution comprises one of the group containing: ammonium acetate, ammonium carbonate, ammonium hydroxide, ammonium nitrate, ammonium perchlorate, ammonium sulfate, ammonium tetrafluoroborate, ammonium trifluoroacetate, ammonium trifluoromethanesulfonate [NH 4 (CF 3 SO 3 )], and a mixture of ammonium fluoride, water, and ethylenediamine.  
     
     
         7 . The method according to  claim 4  where said indicator comprises a complexing agent.  
     
     
         8 . The method according to  claim 7  wherein said complexing agent comprises one of the group containing: diamines, amine macrocycles, and monoamines.  
     
     
         9 . The method according to  claim 8  wherein said complexing agent is a diamine and comprises one of the group containing: H 2 NCH 2 CH 2 N(C 2 H 5 ) 2 (ethylenediamine), (C 2 H 5 ) 2 NCH 2 CH 2 N(C 2 H 5 ) 2 , (N,N,N′,N′-tetraethylenediamine),  
       
         
           
           
               
               
           
         
       
       (EDTA), 1,10-phenanthroline, and 2,2′-bipyridine-4,4′-dicarboxylic acid.  
     
     
         10 . The method according to  claim 8  wherein said completing agent is an amine macrocycle.  
     
     
         11 . The method according to  claim 10  wherein said complexing agent is 1,4,8-triazacycloundecane.  
     
     
         12 . The method according to  claim 10  wherein said completing agent is 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane.  
     
     
         13 . The method according to  claim 10  wherein said complexing agent is 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid dihydrachloride.  
     
     
         14 . The method according to  claim 8  wherein said complexing agent is a monoamine and comprises one of the group containing: triethylamine, tripropylamine, tribenzylamine, 1-methyl 2-piperidinemethanol, and N,N-diethylethanolamine (HOCH 2 CH 2 N(C 2 H 5 ) 2 ).  
     
     
         15 . A method of copper stripping in the fabrication of an integrated circuit comprising: 
 stripping copper using wet copper stripping chemicals whereby an eluent is produced;    continuously analyzing said eluent by colorimetric analysis for the presence of copper; and    stopping said copper stripping process when said presence of copper is no longer detected.    
     
     
         16 . The method according to  claim 15  wherein said presence of said copper is detected by a reaction of said copper with an indicator added to said wet stripping chemicals.  
     
     
         17 . The method according to  claim 16  where said indicator comprises Fast Sulphon Black F indicator and an ammonium ion-containing solution.  
     
     
         18 . The method according to  claim 17  wherein said ammonium ion-containing solution comprises one of the group containing: ammonium acetate, ammonium carbonate, ammonium hydroxide, ammonium nitrate, ammonium perchlorate, ammonium sulfate, ammonium tetrafluoroborate, ammonium trifluoroacetate, ammonium trifluoromethanesulfonate [NH 4 (CF 3 SO 3 )], and a mixture of ammonium fluoride, water, and ethylenediamine.  
     
     
         19 . The method according to  claim 16  where said indicator comprises a complexing agent.  
     
     
         20 . The method according to  claim 19  wherein said complexing agent comprises one of the group containing: diamines, amine macrocycles, and monoamines.  
     
     
         21 . The method according to  claim 19  wherein said complexing agent is a diamine and comprises one of the group containing: H 2 NCH 2 CH 2 N(C 2 H 5 ) 2 (ethylenediamine), (C 2 H 5 ) 2 NCH 2 CH 2 N(C 2 H 5 ) 2 (N,N,N′,N′-tetraethylenediamine),  
       
         
           
           
               
               
           
         
       
       (EDTA), 1,10-phenanthroline, and 2,2′-bipyridine-4,4′-dicarboxylic acid.  
     
     
         22 . The method according to  claim 19  wherein said complexing agent is an amine macrocycle.  
     
     
         23 . The method according to  claim 19  wherein said complexting agent is a monoamine and comprises one of the group containing: triethylamine, tripropylamine, tribenzylamine, 1-methyl 2-piperidinemethanol, and N,N-diethylethanolamine (HOCH 2 CH 2 N(C 2 H 5 ) 2 ).  
     
     
         24 . A composition of matter that serves as an indicator of the presence of copper by colorimetric analysis comprising: 
 Fast Sulphon Black F indicator; and    an ammonium ion-containing solution.    
     
     
         25 . The composition of matter according to  claim 24  wherein said ammonium ion-containing solution comprises one of the group containing: ammonium acetate, ammonium carbonate, ammonium hydroxide, ammonium nitrate, ammonium perchlorate, ammonium sulfate, ammonium tetrafluoroborate, ammonium trifluoroacetate, ammonium trifluoromethanesulfonate [NH 4 (CF 3 SO 3 )], and a misture of ammonium flouride, water, and ethylenediamine.  
     
     
         26 . A composition of matter that serves as an indicator of the presence of copter by colorimetric analysis comprising a complexing agent.  
     
     
         27 . The composition of matter according to  claim 26  wherein said complexing agent comprises one of the group containing: diamines, amine macrocycles, and monoamines.  
     
     
         28 . The composition of matter according to  claim 26  wherein said complexing agent is a diamine and comprises one of the group containing: H 2 NCH 2 CH 2 N(C 2 H 5 ) 2 (ethylenediamine), (C 2 H 5 ) 2 NCH 2 CH 2 N(C 2 H 5 ) 2 , (N,N,N′,N′-tetraethylenediamine),  
       
         
           
           
               
               
           
         
       
       (EDTA), 1,10-phenanthroline, and 2,2′-bipyridine-4,4′-dicarboxylic acid.  
     
     
         29 . The composition of matter according to  claim 26  wherein said complexing agent is an amine macrocycle.  
     
     
         30 . The method according to  claim 29  wherein said coulplexing agent is 1,4,8-triazacycloundecane.  
     
     
         31 . The method according to  claim 29  wherein said complexing agent is 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotradecane.  
     
     
         32 . The method according to  claim 29  wherein said complexting agent is 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid dihydrachloride.  
     
     
         33 . The composition of matter according to  claim 26  wherein said complexing agent is a monoamine and comprises one of the group containing: triethylamine, tripropylamine, tribenzylamine, 1-methyl 2-piperidinemethanol, and N,N-diethylethanolamine (HOCH 2 CH 2 N(C 2 H 5 ) 2 ).