Plating of a thin metal seed layer

Abstract

A method and apparatus for plating a metal layer onto a substrate is provided. The plating apparatus includes two or more segments of an anode and an auxiliary electrode. The plating method includes a first stage of plating a thin metal seed uniformly in the center of the substrate and near the edges of the substrate before metal gap filling and bulk metal plating are performed. The thin metal seed is plated on the substrate surface by applying a current pulse provided by a first power supply and a second power supply which are in electrical communication in reverse polarity with one segment of the anode and the auxiliary electrode. Thereafter, gap filling of features is performed by applying a second current pulse where current is provided to all segments of the anode.

1 . A method of plating a metal layer onto a substrate in a plating cell having a central anode segment, one or more other anode segments, and an auxiliary electrode, comprising: 
 plating a first portion of the metal layer on the surface of the substrate under a first processing condition to at least cover a large portion of the substrate, the first processing condition comprising electrically connecting a first power supply to the central anode segment and the substrate.    
     
     
         2 . The method of  claim 1 , wherein the first processing condition further comprises: 
 electrically connecting a second power supply to the auxiliary electrode and the substrate.    
     
     
         3 . The method of  claim 2 , wherein the first and the second power supply are connected to the central anode segment and the auxiliary electrode in reverse polarity.  
     
     
         4 . The method of  claim 2 , wherein the current going through the substrate is greater than the current going through the auxiliary electrode.  
     
     
         5 . The method of  claim 2 , wherein the current going through the central anode segment is greater than the current going through the auxiliary electrode.  
     
     
         6 . The method of  claim 1 , wherein the thickness of the metal layer is about 30 Å to about 250 Å.  
     
     
         7 . The method of  claim 1 , wherein the central anode segment is aligned with a middle region of the substrate.  
     
     
         8 . The method of  claim 1 , wherein the auxiliary electrode is located near the peripheral edges of the substrate.  
     
     
         9 . The method of  claim 1 , further comprising: 
 plating a second portion of the metal layer under a second processing condition to at least fill gaps between features on the surface of the substrate, wherein the second processing condition comprises electrically connecting a power supply to all anode segments and the substrate.    
     
     
         10 . The method of  claim 9 , wherein the thickness of the metal layer is between about 50 Å to about 1000 Å.  
     
     
         11 . The method of  claim 1 , further comprising: 
 plating a third portion of the metal layer under a third processing condition to deposit at least a portion of a bulk layer on the surface of the substrate, wherein the thickness of the metal layer is more than about 800 Å.    
     
     
         12 . The method of  claim 1 , wherein the central anode segment is aligned with a middle area of the substrate.  
     
     
         13 . The method of  claim 1 , wherein the metal layer comprises copper.  
     
     
         14 . A method of plating a metal layer onto a substrate in a plating cell having a first and a second electrode, comprising: 
 connecting a first power supply to a central segment of the first electrode and the substrate;    connecting a second power supply to the second electrode and the substrate; and    plating a first portion of the metal layer on the surface of the substrate at reverse polarity of the first and the second electrodes.    
     
     
         15 . The method of  claim 14 , wherein the current going through the substrate is greater than the current going through the second electrode.  
     
     
         16 . The method of  claim 14 , wherein the current going through the central segment of the first electrode is greater than the current going through the second electrode.  
     
     
         17 . The method of  claim 14 , wherein the thickness of the metal layer is about 30 Å to about 250 Å.  
     
     
         18 . The method of  claim 14 , further comprising: 
 plating a second portion of the metal layer under a second processing condition to at least fill gaps between features on the surface of the substrate, wherein the second processing condition comprises electrically connecting all segments of the first electrode.    
     
     
         19 . The method of  claim 14 , further comprising: 
 plating a third portion of the metal layer under a third processing condition to deposit at least a portion of a bulk layer on the surface of the substrate, wherein the thickness of the metal layer is more than about 800 Å.    
     
     
         20 . A method of plating a metal layer onto a substrate in a plating cell having two or more segments of an anode and an second electrode, comprising: 
 applying a first current pulse to the substrate to deposit a first portion of the metal layer on the surface of the substrate, the first current pulse being provided by a first power supply and a second power supply which are in electrical communication in reverse polarity with at least one segment of the anode and the second electrode, respectively; and    applying a second current pulse to the substrate to deposit a second portion of the metal layer on the surface of the substrate, the second current pulse comprising currents provided to all segments of the anode.    
     
     
         21 . The method of  claim 20 , wherein the at least one segment of the anode is aligned with a central region of the substrate.  
     
     
         22 . The method of  claim 20 , wherein the auxiliary electrode is located near the peripheral edges of the substrate.  
     
     
         23 . The method of  claim 20 , wherein the metal layer comprises copper.  
     
     
         24 . A method of plating a metal layer onto a substrate in a plating cell having two or more segments of an anode and an second electrode, comprising: 
 applying an electrical flux in a reverse direction toward the peripheral of the substrate to deposit a first portion of the metal layer on the surface of the substrate, the electrical flux being provided by a first power supply and a second power supply which are in electrical communication with at least one segment of the anode and the second electrode, respectively.    
     
     
         25 . A method of plating a metal layer onto a substrate in a plating cell having a central anode segment and one or more other anode segments, comprising: 
 plating the metal layer on the surface of the substrate under a first processing condition to at least cover a large portion of the substrate, the first processing condition comprising applying more current to the central anode segment than current applied to the one or more other anode segments;    plating under a second processing condition to at least fill gaps between features on the surface of the substrate; and    plating under a third processing condition to deposit at least a bulk portion of the metal layer on the surface of the substrate.    
     
     
         26 . The method of  claim 25 , further comprising: 
 deplating any contaminants from contact points of the plating cell; and    plating a thin metal layer on contact points of a plating apparatus in the absence of the substrate before plating the metal layer onto the substrate.    
     
     
         27 . The method of  claim 25 , wherein the metal coating comprises copper and the thickness of the metal coating is less than about 600 Å.