Wet etch of titanium-tungsten film

Abstract

A conventional and economical method to etch TiW alloys and remove the etch residues therefrom is disclosed. The composition of the present invention contains periodic acid (PIA). Such compositions, when used in optimal conditions, are effective in etching TiW alloys, and also in removing the etch residues resulting from TiW alloys. Moreover, the composition of the present invention causes relatively little etching on Al, Cu, or AlCu layers.

What is claimed is:  
     
         1 . A TiW-selective composition comprising water and between about 5% and about 20% by weight of periodic acid, wherein the composition is effective in removing a TiW alloy and removing residues of etching of TiW alloy while removing a relatively small amount of Al, Cu, or an AlCu alloy, and wherein the pH of the composition is less than 7.  
     
     
         2 . The composition of  claim 1 , wherein the composition is substantially free of hydrofluoric acid.  
     
     
         3 . The composition of  claim 1 , wherein the pH of the composition is less than about 4.  
     
     
         4 . The composition of  claim 1 , wherein the pH of the composition is less than about 2.  
     
     
         5 . The composition of  claim 1 , wherein the composition contains periodic acid in an amount from about 7.5% to about 15% by weight of the composition.  
     
     
         6 . The composition of  claim 1 , wherein the composition contains periodic acid in an amount from about 8% to about 12% by weight of the composition.  
     
     
         7 . The composition of  claim 1 , wherein the composition contains periodic acid in an amount of about 10% by weight of the composition.  
     
     
         8 . A method of etching and cleaning a TiW alloy layer comprising: 
 providing a substrate comprising an exposed TiW alloy layer;    etching the TiW alloy by a method which results in formation of etching residue;    contacting the substrate with the composition of  claim 1  for a time and at a temperature sufficient to cause the composition to remove at least a portion of the TiW alloy and substantially all of the etching residue from the substrate; and    rinsing the substrate.    
     
     
         9 . The method of  claim 8 , wherein the substrate further comprises an exposed AlCu alloy, wherein the specificity of removal of TiW to AlCu, in terms of etch rate, is at least about 3.  
     
     
         10 . The method of  claim 9 , wherein the substrate further comprises an exposed AlCu alloy, wherein the specificity of removal of TiW to AlCu, in terms of etch rate, is at least about 5.  
     
     
         11 . The method of  claim 10 , wherein the substrate further comprises an exposed AlCu alloy, wherein the specificity of removal of TiW to AlCu, in terms of etch rate, is at least about 7.  
     
     
         12 . The method of  claim 8 , wherein the temperature at which the solution is used ranges from about 20° C. to about 100° C.  
     
     
         13 . The method of  claim 8 , wherein the temperature at which the solution is used ranges from about 30° C. to about 40° C.  
     
     
         14 . A method of etching and cleaning TiW layer comprising: 
 providing a substrate comprising a TiW alloy layer and etching residues from prior etching of the TiW layer;    contacting the substrate with a solution containing hydrogen peroxide for a time and at a temperature sufficient to cause the solution to substantially remove exposed TiW alloy;    contacting the substrate with the composition of  claim 1  for a time and at a temperature sufficient to substantially remove the residues from the substrate; and    rinsing the substrate.    
     
     
         15 . The method of  claim 14 , wherein the temperature at which the solution is used ranges from about 20° C. to about 100° C.  
     
     
         16 . The method of  claim 15 , wherein the temperature at which the solution is used ranges from about 30° C. to about 40° C.