Method of electroplating low internal stress copper deposits on thin film substrates to inhibit warping

Abstract

Thin film substrates are electroplated with copper from low internal stress, high ductility acid copper electroplating baths. During the copper electroplating process the thin film substrates can warp or bow. To address the problem of warping or bowing during copper electroplating the thin film substrate is held by a securing means which inhibits the thin film substrate from excessive activity.

What is claimed is: 
     
         1 . A method of copper electroplating a thin film substrate comprising:
 a) providing the thin film substrate;   b) attaching the thin film substrate to a securing means to inhibit substantially all motion of the thin film substrate in relation to the securing means;   c) attaching one or more electrical contacts to the thin film substrate;   d) passing the thin film substrate attached to the securing means and with the one or more electrical contacts through a low stress, high ductility acid copper electroplating bath wherein the thin film substrate and securing means with the one or more electrical contacts remain substantially in a single plane while passing through the copper electroplating bath; and   e) electroplating low stress, high ductility copper on the thin film substrate with the low stress, high ductility copper electroplating bath.   
     
     
         2 . The method of  claim 1 , wherein the thin film substrate is 220 μm thick or less but greater than 0. 
     
     
         3 . The method of  claim 1 , wherein the thin film substrate attached to the securing means is passed through the low stress, high ductility copper electroplating bath by a conveyor. 
     
     
         4 . The method of  claim 3 , wherein the securing means is a plating jig joined to the conveyor. 
     
     
         5 . The method of  claim 1 , wherein the securing means is a conveyor comprising a grove for securing the thin film substrate during electroplating. 
     
     
         6 . The method of  claim 1 , wherein the securing means is a conveyor comprising a plurality of pairs of rolling balls securing the thin film substrate during electroplating. 
     
     
         7 . The method of  claim 1 , wherein the low internal stress, high ductility acid copper electroplating bath comprises one or more sources of copper ions, an electrolyte, one or more branched polyalkylenimines, one or more accelerators and one or more suppressors. 
     
     
         8 . The method of  claim 1 , wherein the low internal stress, high ductile acid copper electroplating bath comprises one or more sources of copper ions, an electrolyte, one or more polyallylamines, one or more accelerators and one or more suppressors.