Electroplating solutions

Abstract

Aqueous electroplating solution for alkaline electroplating, comprising: [M(NH3)4]2+ ions, wherein M is selected from the group consisting of Pd or Pt; and organic anions selected from the group consisting of bicarbonate, carbonate, or a mixture thereof; wherein the following species, if present, are present in the following amounts: alkali metals in an amount of less than 5 g/L; compounds comprising phosphorus in an amount of less than 5 g/L; compounds comprising boron in an amount of less than 5 g/L. The invention also relates to an electroplating bath comprising the electroplating solution, and a method of forming a metal layer on a substrate by electroplating using the electroplating solution.

What is claimed: 
     
         1 . An aqueous electroplating solution for alkaline electroplating, comprising:
 [Pt(NH 3 ) 4 ] 2+  ions; and organic anions selected from the group consisting of bicarbonate, carbonate, or a mixture thereof;   
       wherein the molar ratio of Pt: (bicarbonate+carbonate) is approximately 1:2; and 
       wherein the following species, if present, are present in the following amounts:
 alkali metals in an amount of less than 5 g/L; 
 compounds comprising phosphorus in an amount of less than 5 g/L; 
 compounds comprising boron in an amount of less than 5 g/L. 
 
     
     
         2 . The aqueous electroplating solution according to  claim 1 , wherein the concentration of Pt in the solution is 1 to 30 g/litre, on a metal basis. 
     
     
         3 . The aqueous electroplating solution according to  claim 1 , wherein the concentration of Pt in the solution is 5 to 30 g/litre, on a metal basis. 
     
     
         4 . The aqueous electroplating solution according to  claim 1 , wherein the concentration of Pt in the solution is 5 to 25 g/litre, on a metal basis. 
     
     
         5 . The aqueous electroplating solution according to  claim 1 , wherein the pH of the solution is 8 to 14. 
     
     
         6 . The aqueous electroplating solution according to  claim 1 , comprising a pH adjusting agent selected from the group consisting of ammonia, urea, an alkylammonium hydroxide, ammonium hydroxide, ammonium bicarbonate and ammonium carbonate. 
     
     
         7 . The aqueous electroplating solution according to  claim 1 , wherein the content of alkali metals is less than 0.1 g/L. 
     
     
         8 . The aqueous electroplating solution according to  claim 1 , wherein the content of halide ions in the electroplating solution is less than 1 g/L. 
     
     
         9 . The aqueous electroplating solution according to  claim 1 , wherein the content of nitrite ions in the electroplating solution is less than 0.5 g/L. 
     
     
         10 . The aqueous electroplating solution according to  claim 1 , wherein the content of nitrate ions in the electroplating solution is less than 0.5 g/L. 
     
     
         11 . The aqueous electroplating solution according to  claim 1 , wherein the content of compounds containing silicon is less than 0.5 g/L. 
     
     
         12 . The aqueous electroplating solution according to  claim 1 , wherein the content of compounds containing sulfur is less than 0.5 g/L.