Die-level wafer contact for direct-on-barrier plating

Abstract

The present invention provides a semiconductor workpiece support and contact assembly for providing localized electrical connections with the device side of the workpiece. The additional contact points help overcome the terminal effect caused by very high sheet resistance of thin barrier layers and enable plating a conformal seed layer or feature filling directly on thin barrier layers. By utilizing the streets that separate individual dice on a workpiece to make electrical connections with the workpiece and provide localized distribution of plating chemistry, the present invention provides a more uniform and conformal metallization layer.

1 . A semiconductor contact assembly for use in a semiconductor electroplating apparatus used to plate a metal or metals onto a semiconductor workpiece having a plurality of streets, comprising: 
 an outer continuous shoulder that defines an inner area;    a plurality of conductive contact members connected to the outer continuous shoulder and extending into the open area to form a plurality of openings in the inner area; and    at least one recess formed in the outer shoulder.    
   
   
       2 . The semiconductor contact assembly of  claim 1 , wherein the plurality of conductive contact members lie within a common horizontal plane.  
   
   
       3 . The semiconductor contact assembly of  claim 1 , wherein the plurality of openings in the contact assembly are substantially square shaped.  
   
   
       4 . The semiconductor contact assembly of  claim 1 , wherein the plurality of openings in the contact assembly are substantially rectangular shaped.  
   
   
       5 . The semiconductor contact assembly of  claim 1 , wherein the at least one recess formed in the outer shoulder comprises two opposed recesses.  
   
   
       6 . The semiconductor contact assembly of  claim 1 , wherein the plurality of conductive contact members intersect one another to form a grid.  
   
   
       7 . The semiconductor contact assembly of  claim 1 , wherein the plurality of conductive contact members comprise a plurality of discrete contact points.  
   
   
       8 . The semiconductor contact assembly of  claim 1  further comprising an electrical connector to provide electrical power to the contact assembly.  
   
   
       9 . The semiconductor contact assembly of  claim 1 , wherein the plurality of conductive contact members have a width in a range of 0.5 to 5 mm.  
   
   
       10 . The semiconductor contact assembly of  claim 9 , wherein the width is in a range of 1 to 2 mm.  
   
   
       11 . The semiconductor contact assembly of  claim 1  further comprising a plate for distributing process fluid to the semiconductor workpiece that rests on the plurality of conductive contact members.  
   
   
       12 . The semiconductor contact assembly of  claim 11 , wherein the plate comprises a plurality of spaced apart cells projecting outwardly from a base, the cells configured to rest within the openings of the inner area and the space between the cells configured to receive the conductive contact members.  
   
   
       13 . The semiconductor contact assembly of  claim 12 , wherein each of the plurality of spaced apart cells has at least one aperture.  
   
   
       14 . The semiconductor contact assembly of  claim 13 , wherein each of the plurality of spaced apart cells has a plurality of apertures.  
   
   
       15 . A semiconductor support and contact assembly for use in plating a semiconductor workpiece having a plurality of microelectronic devices formed on one side, the plurality of microelectronic devices being separated from one another by streets, the semiconductor support and contact assembly comprising a plurality of point contacts provided on a frame having a plurality of openings, whereby upon placing the workpiece on the semiconductor support and contact assembly the plurality of point contacts make a plurality of electrical connections with the semiconductor workpiece along the streets.  
   
   
       16 . An apparatus for plating a metal onto a semiconductor workpiece, comprising: 
 a bowl assembly adapted to hold a plating fluid;    an anode positioned in the bowl assembly;    a contact assembly located in the bowl assembly, the contact assembly having a frame that defines an inner area and a plurality of conductive contact members connected to the frame and forming a plurality of openings in the inner area; and    a process head for placing the semiconductor workpiece onto the contact assembly.    
   
   
       17 . The apparatus of  claim 16  further comprising a plate having a plurality of apertures for distributing the plating fluid to the semiconductor workpiece.  
   
   
       18 . The apparatus of  claim 16 , wherein the contact assembly comprises a plurality of discrete contact points for making an electrical connection with the semiconductor workpiece.  
   
   
       19 . The apparatus of  claim 16  wherein the bowl assembly comprises a bowl having an inlet and outlet port for selectively introducing a electrolyte into the bowl.  
   
   
       20 . The apparatus of  claim 19 , wherein a membrane divides the bowl into first and second compartments.  
   
   
       21 . The apparatus of  claim 16  further comprising a power supply for selectively powering the plurality of conductive members.  
   
   
       22 . The apparatus of  claim 16 , wherein the workpiece has a plurality of streets and the contact members are electrically connected to the streets.  
   
   
       23 . The apparatus of  claim 22 , wherein conductive members are positioned within the streets and the contact assembly is in electrical contact with the conductive members of the streets.  
   
   
       24 . The apparatus of  claim 16 , wherein a portion of the contact members are covered with a material resistant to electrochemical plating.  
   
   
       25 . A method for plating a metal onto a surface of a semiconductor workpiece, comprising: 
 providing a semiconductor workpiece having a plurality of microelectronic devices and streets formed on one side thereof;    placing the semiconductor workpiece on a contact assembly having a plurality of conductive members wherein the conductive members contact the semiconductor workpiece at one of the streets;    applying a plating bath fluid to the one side of the semiconductor workpiece; and    electroplating a metal onto the semiconductor workpiece by passing electrical current through the plurality of conductive members and between the semiconductor workpiece and the contact assembly.    
   
   
       26 . The method of  claim 25 , wherein the contact assembly comprises a contact plate and a plate for distributing the plating bath fluid to the one side of the semiconductor workpiece.  
   
   
       27 . The method of  claim 26 , wherein the contact plate and the fluid distribution plate are generally co-planar.  
   
   
       28 . The method of  claim 25 , wherein the contact members lie within a common horizontal plane.  
   
   
       29 . The method of  claim 25 , wherein electrical current is passed through some but not all of the conductive members.  
   
   
       30 . The method of  claim 25 , wherein the contact assembly is comprised of a contact plate having a plurality point contacts and a plurality of openings.  
   
   
       31 . The method of  claim 30 , wherein the contact further comprises a plate having a plurality of apertures for distributing the plating bath fluid to the one side of the semiconductor workpiece.