Solution and process for the activation of nonconductive area for electroless process

Abstract

The present invention discloses a novel activator system for electroless metallization deposition, particularly activators that may be free of tin and surfactants. Activators of the invention are preferably employed for electroless copper deposition.

1 . A method for depositing an electroless plating activator on a substrate, comprising:
 (a) providing a substrate;   (b) applying an activator composition to the substrate;   (c) applying a reducing agent to the substrate;   wherein the activator composition comprising at least one metal ion and at least one organic acid; wherein the organic acid has at least one carboxylic group and at least one hydroxyl group.   
     
     
         2 . The method of  claim 1 , wherein the organic acid is dicarboxyl acid terminated and has a formula:
   HOOC—R 1 —COOH  (I)
   wherein R 1  is chosen from linear or branched, substituted or unsubstituted (C 1 -C 6 )alcohol.   
     
     
         3 . The method of  claim 2 , wherein the organic acid is selected from the group consisting of tartaric acid, citric acid, malic acid, and 2,2-Bis(hydroxymethyl)malonic acid. 
     
     
         4 . The method of  claim 3 , wherein the organic acid is tartaric acid or malic acid. 
     
     
         5 . The method of  claim 1 , wherein the organic acid has a formula:
   R 2 —COOH  (II)
   wherein R 2  is chosen from linear or branched, substituted or unsubstituted (C 1 -C 6 )alcohol.   
     
     
         6 . The method of  claim 5 , wherein the organic acid is selected from the group consisting of glyceric acid, glycolic acid, and lactic acid. 
     
     
         7 . The method of  claim 6 , wherein the organic acid is glyceric acid. 
     
     
         8 . The method of  claim 1 , wherein the metal ion is selected from the group consisting of palladium, copper, silver, gold, platinum, iridium, aluminum, cobalt and nickel ions. 
     
     
         9 . The method of  claim 8 , wherein the metal ion is copper. 
     
     
         10 . The method of  claim 1 , wherein the pH of activator composition is greater than 9. 
     
     
         11 . The method of  claim 1 , wherein the reducing agent comprises DMAB or NaBH 4 . 
     
     
         12 . A method for forming an electroless copper plating film on a substrate, comprising:
 (a) depositing an electroless plating activator on the substrate by the method of  claim 1 ;   (b) electrolessly plating copper on the substrate.   
     
     
         13 . The method of  claim 12 , wherein the step (b) uses a plating bath comprising: tartrate, copper ions, formaldehyde, and 2,2-dipyridine.