Electroplating method

Abstract

An electroplating method not that is especially suited for the filling of vias is provided. In this method, a current is applied in a forward method for a set period of time and then reversed for a set period of time. This method utilizes a rest time either before or after or both before and after the reverse current period.

What is claimed is:  
     
         1 . A method of electroplating a metal layer on a substrate comprising contacting the substrate with a metal electroplating bath and applying sufficient current density to deposit a desired metal layer, wherein the current density is applied for a cycle of 1 to 50 msec positive electrolysis time, 0.2 to 5 msec reverse electrolysis time and 0.1 to 20 msec rest time.  
     
     
         2 . The method of  claim 1  wherein the metal electroplating bath is a copper electroplating bath.  
     
     
         3 . The method of  claim 2  wherein the copper electroplating bath comprises copper sulfate.  
     
     
         4 . The method of  claim 1  wherein the metal electroplating bath comprises a grain refiner.  
     
     
         5 . The method of  claim 1  wherein the rest time is performed prior to the reverse electrolysis time.  
     
     
         6 . The method of  claim 1  wherein rest time is performed after the reverse electrolysis time.  
     
     
         7 . The method of  claim 1  wherein rest time is performed before and after the reverse electrolysis time.  
     
     
         8 . The method of  claim 1  wherein the substrate is a printed circuit board.  
     
     
         9 . The method of  claim 1  wherein the substrate is an integrated circuit substrate.  
     
     
         10 . An electroplating method wherein a current is applied for a cycle of 1 to 50 msec positive electrolysis time, 0.2 to 5 msec reverse electrolysis time and 0.1 to 20 msec rest time.