Reactors, systems, and methods for electroplating microfeature workpieces

Abstract

Reactors, systems and methods for electroplating and/or electro-etching microfeature workpieces. Reactors in accordance with the invention have a first chamber configured to direct a first processing solution to a processing zone, a second chamber configured to contain a second processing solution different than the first processing solution, and an ion exchange membrane between the first chamber and the second chamber. The reactors also include (a) a support member in the first chamber that contacts the ion exchange membrane across the surface of the membrane, and (b) a counter electrode in the second chamber. The ion exchange membrane enables a low conductivity catholyte to be used in the first chamber and an inert counter electrode in the second chamber. More specifically, the ion exchange membrane prevents nascent oxygen that evolves from the inert counter electrode from reaching the catholyte to reduce oxidation of constituents of the catholyte, consumption of organic additives in the anolyte, and/or accumulation of bubbles and particulates at the workpiece.

1 . A reactor for electrochemical processing of microfeature workpieces, comprising: 
 a vessel;    a workpiece holder having an electrical contact to apply an electrical potential to a workpiece, wherein the workpiece holder is configured to position a workpiece in a processing zone relative to the vessel;    a first chamber in the vessel configured to direct a first processing solution to the processing zone;    an inlet at the first chamber;    a second chamber in the vessel configured to contain a second processing solution different than the first processing solution;    an ion exchange membrane between the first chamber and the second chamber, the ion exchange membrane having a first surface facing the first chamber and a second surface facing the second chamber;    a support member in the first chamber at the inlet, wherein the support member contacts the ion exchange membrane across the first surface of the ion exchange membrane and directs a flow of the first processing solution from the inlet toward the processing zone; and    an electrode in the second chamber.    
   
   
       2 . The reactor of  claim 1  wherein the support member comprises a flow distributor having plate, standoffs projecting from the plate and contacting the first surface of the ion exchange membrane, and openings through the plate.  
   
   
       3 . The reactor of  claim 2  wherein the standoffs and the openings are configured to direct a flow of the first processing solution across the first surface of the ion exchange membrane and upwardly through the openings.  
   
   
       4 . The reactor of  claim 2  wherein the plate has a first region and a second region, and wherein the openings include first openings in the first region and second openings in the second region that are configured to provide a first electrical field component relative to the first region and a second electrical field component relative to the second region.  
   
   
       5 . The reactor of  claim 1  wherein the support member spans across the first surface of the ion exchange membrane, and wherein the support member has a plenum over the first surface of ion exchange membrane and outlets above the plenum through which a flow of the first processing solution passes toward the workpiece processing zone.  
   
   
       6 . The reactor of  claim 1  wherein the support member comprises a plate having a first side contacting the first surface of the ion exchange membrane to control a profile of the ion exchange membrane across the vessel and a second side facing the processing zone.  
   
   
       7 . The reactor of  claim 6  wherein the plate has lands with bearing surfaces at the first side in contact with the ion exchange membrane and a flow channel configured to distribute a flow of the first processing solution across the first surface of the ion exchange membrane.  
   
   
       8 . The reactor of  claim 1  wherein the electrode in the second chamber comprises an inert anode.  
   
   
       9 . The reactor of  claim 1  wherein the electrode in the second chamber has a planar upper region and a curved central region with a slope that provides at least a substantially constant area of electrode surface relative to a radial position across the processing zone.  
   
   
       10 . The reactor of  claim 1 , further comprising a seal encompassing a peripheral edge of the ion exchange membrane.  
   
   
       11 . The reactor of  claim 10  wherein the seal comprises a ring having a C-shaped cross-section with a slot configured to receive a peripheral portion of the ion-exchange membrane.  
   
   
       12 . The reactor of  claim 11 , further comprises a clamp engaged with the seal to press a first portion of the seal against the first surface of the ion exchange membrane and a second portion of the seal against the second surface of the ion exchange membrane.  
   
   
       13 . The reactor of  claim 1 , further comprising a flow diffuser around the perimeter of the electrode.  
   
   
       14 . The reactor of  claim 13 , further comprising a dielectric strap between the perimeter of the electrode and the flow diffuser.  
   
   
       15 . The reactor of  claim 1  wherein the first chamber comprises a catholyte compartment and the second chamber comprises an anolyte compartment.  
   
   
       16 . The reactor of  claim 1  wherein the ion exchange membrane comprise at least one of an anion exchange membrane and a cation exchange membrane.  
   
   
       17 . The reactor of  claim 1  wherein the first chamber has a first depth between the ion exchange membrane and the processing zone of approximately 0.5 inch to 6 inches and the second chamber has a gap between a perimeter portion of the electrode and the ion exchange membrane of approximately 0.05 inch to 2 inches.  
   
   
       18 . The reactor of  claim 1  wherein: 
 the plate has lands with bearing surfaces at the first side in contact with the ion exchange membrane and a flow channel configured to distribute a flow of the first processing solution across the first surface of the ion exchange membrane;    the electrode in the second chamber comprises an inert anode; and    the first chamber comprises a catholyte compartment and the second chamber comprises an anolyte compartment.    
   
   
       19 . The reactor of  claim 1  wherein: 
 the support member spans across the first surface of the ion exchange membrane, and wherein the support member has a plenum over the first surface of ion exchange membrane and outlets above the plenum through which a flow of the first processing solution passes toward the workpiece processing zone;    the electrode in the second chamber comprises an inert anode; and    the ion exchange membrane comprise at least one of an anion exchange membrane and a cation exchange membrane.    
   
   
       20 . The reactor of  claim 1  wherein: 
 the support member spans across the first surface of the ion exchange membrane, and wherein the support member has a plenum over the first surface of ion exchange membrane and outlets above the plenum through which a flow of the first processing solution passes toward the workpiece processing zone;    the electrode in the second chamber comprises an inert anode;    the ion exchange membrane comprise at least one of an anion exchange membrane and a cation exchange membrane; and    the first chamber has a first depth between the ion exchange membrane and the processing zone of approximately 0.5 inch to 6 inches and the second chamber has a gap between a perimeter portion of the electrode and the ion exchange membrane of approximately 0.05 inch to 2 inches.    
   
   
       21 . A reactor for electrochemical processing of microfeature workpieces, comprising: 
 a vessel;    a workpiece holder having an electrical contact to apply an electrical potential to a workpiece, wherein the workpiece holder is configured to position a workpiece in a processing zone relative to the vessel;    a first chamber in the vessel configured to direct a first processing solution to the processing zone;    a second chamber in the vessel configured to contain a second processing solution different than the first processing solution;    an ion exchange membrane between the first chamber and the second chamber, the ion exchange membrane having a first surface facing the first chamber and a second surface facing the second chamber;    a flow director in the first chamber juxtaposed to the first surface of the ion exchange membrane, the flow director being configured to (a) distribute the first processing solution across the first surface of the ion exchange membrane and (b) direct the first processing fluid to the processing zone; and    an electrode in the second chamber.    
   
   
       22 . The reactor of  claim 21  wherein the flow director comprises support member having plate, standoffs projecting from the plate and contacting the first surface of the ion exchange membrane, and openings through the plate.  
   
   
       23 . The reactor of  claim 22  wherein the standoffs and the openings are configured to direct a flow of the first processing solution across the first surface of the ion exchange membrane and upwardly through the openings.  
   
   
       24 . The reactor of  claim 22  wherein the plate has a first region and a second region, and wherein the openings include first openings in the first region and second openings in the second region that are configured to provide a first electrical field component relative to the first region and a second electrical field component relative to the second region.  
   
   
       25 . The reactor of  claim 22  wherein the flow director comprises a support member that spans across the first surface of the ion exchange membrane, and wherein the support member has a plenum over the first surface of ion exchange membrane and outlets above the plenum through which a flow of the first processing solution passes toward the workpiece processing zone.  
   
   
       26 . The reactor of  claim 21  wherein the flow director comprises a plate having a first side contacting the first surface of the ion exchange membrane to control a profile of the ion exchange membrane across the vessel and a second side facing the processing zone.  
   
   
       27 . A reactor for electrochemical processing of microfeature workpieces, comprising: 
 a workpiece holder having an electrical contact to apply an electrical potential to a workpiece, wherein the workpiece holder is configured to position a workpiece in a processing zone;    an ion exchange membrane having a first side and a second side;    a first flow cell on the first side of the ion exchange membrane configured to contain a first processing fluid, the first flow cell having a first inlet through which the first processing solution can flow;    a first flow distributor in the first flow cell configured to (a) direct a flow of the first processing solution from the inlet to the first side of the ion exchange membrane and (b) shape the first side of the ion exchange membrane;    a second flow cell on the second side of the ion exchange membrane configured to contain a second processing solution separately from the first processing solution; and    an electrode in the second flow cell, wherein the electrode is spaced apart from the ion exchange membrane by a gap through which a flow of the second processing solution can move radially outwardly across the second side of the ion exchange membrane.    
   
   
       28 . The reactor of  claim 27 , further comprising a flow diffuser around the perimeter of the electrode.  
   
   
       29 . The reactor of  claim 28 , further comprising a dielectric strap between the perimeter of the electrode and the flow diffuser.  
   
   
       30 . The reactor of  claim 27  wherein the first flow cell comprises a catholyte compartment and the second flow cell comprises an anolyte compartment.  
   
   
       31 . The reactor of  claim 27  wherein the ion exchange membrane comprise at least one of an anion exchange membrane and a cation exchange membrane.  
   
   
       32 . The reactor of  claim 27  wherein the first flow cell has a first depth between the ion exchange membrane and the processing zone of approximately 0.5 inch to 6 inches and the gap between the electrode and the ion exchange membrane is approximately 0.05 inch to 2 inches.  
   
   
       33 . An apparatus for electrochemically processing a seed layer on a microfeature workpiece, comprising: 
 a vessel;    a workpiece holder having an electrical contact to apply an electrical potential to a workpiece, wherein the workpiece holder is configured to position a workpiece in a processing zone relative to the vessel;    a first chamber in the vessel configured to direct a first processing solution to the processing zone;    a second chamber in the vessel configured to contain a second processing solution different than the first processing solution;    an ion exchange membrane between the first chamber and the second chamber, the ion exchange membrane having a first surface facing the first chamber and a second surface facing the second chamber; and    an inert electrode in the second chamber, wherein the electrode is spaced apart from the processing zone by a distance to provide a sufficient electrical field in a high pH processing solution suitable for seed layer processing using 120V power.    
   
   
       34 . The apparatus of  claim 33  wherein the distance between the electrode and the processing zone is approximately 1 inch to 6 inches.  
   
   
       35 . The apparatus of  claim 33  wherein the distance between the electrode and the processing zone is approximately 1.5-4 inches.  
   
   
       36 . An apparatus for electrochemically processing a microfeature workpiece, comprising: 
 a vessel;    a workpiece holder having an electrical contact to apply an electrical potential to a workpiece, wherein the workpiece holder is configured to position a workpiece in a processing zone relative to the vessel;    a first chamber in the vessel configured to direct a first processing solution to the processing zone;    a second chamber in the vessel configured to contain a second processing solution different than the first processing solution;    an ion exchange membrane between the first chamber and the second chamber, the ion exchange membrane having a first surface facing the first chamber and a second surface facing the second chamber; and    a seal encompassing a peripheral edge of the ion exchange membrane.    
   
   
       37 . The apparatus of  claim 36  wherein the seal comprises a ring having a C-shaped cross-section with a slot configured to receive a peripheral portion of the ion-exchange membrane.  
   
   
       38 . The apparatus of  claim 36 , further comprising a clamp engaged with the seal to press a first portion of the seal against the first surface of the ion exchange membrane and a second portion of the seal against the second surface of the ion exchange membrane.  
   
   
       39 . A method of electrochemically processing microfeature workpieces, comprising: 
 directing a flow of a first processing solution across a first surface of an ion exchange membrane and to a workpiece processing zone in a first flow cell of a vessel;    directing a flow of a second processing solution across a second surface of the ion exchange membrane facing a second flow cell of the vessel, wherein the first processing solution is different than the second processing solution; and    supporting a middle portion of the first surface of the ion exchange membrane while directing the flow of the second processing solution across the second surface of the ion exchange membrane.    
   
   
       40 . The method of  claim 39 , further comprising providing a support member extending across the first flow cell, wherein the support member has a first side contacting a middle portion of the first surface of the ion exchange membrane and a flow channel through which the flow of first processing solution flows across the first surface of the ion exchange membrane.  
   
   
       41 . The method of  claim 40 , wherein the support member further comprises openings facing the processing zone, and wherein directing the flow of the first processing solution comprises passing the first processing solution through the openings to the workpiece processing zone.  
   
   
       42 . The method of  claim 39  wherein the first processing solution comprises a catholyte and the second processing solution comprises an anolyte.  
   
   
       43 . The method of  claim 42 , further comprising passing an electrical current between an electrode in the second flow cell and a workpiece at the processing zone in the first flow cell.  
   
   
       44 . The method of  claim 42 , further comprising passing an electrical current between an inert electrode in the second flow cell and a workpiece at the processing zone in the first flow cell.  
   
   
       45 . The method of  claim 44 , further comprising using the first processing solution for more than 2,000 Amp-minutes before changing out the first processing solution.  
   
   
       46 . The method of  claim 44 , further comprising using the first processing solution for more than 8,000 Amp-minutes before changing out the first processing solution.  
   
   
       47 . The method of  claim 39 , further comprising: 
 raising the second processing solution to contact the second surface of the ion exchange membrane;    passing an electrical current between an inert electrode in the second flow cell and a workpiece at the processing zone in the first flow cell while the second processing solution contacts the second surface of the ion exchange membrane; and    lowering the second processing solution from the second surface of the ion exchange membrane after processing a surface of the workpiece.    
   
   
       48 . The method of  claim 39 , further comprising: 
 providing a first processing solution comprising a low conductivity, high pH catholyte;    passing an electrical current between an inert electrode in the second flow cell and a workpiece at the processing zone in the first flow cell while the second processing solution contacts the second surface of the ion exchange membrane; and    lowering the second processing solution from the second surface of the ion exchange membrane after processing a surface of the workpiece.    
   
   
       49 . The method of  claim 48 , further comprising using the first processing solution for more than 2,000 Amp-minutes before changing out the first processing solution.  
   
   
       50 . The method of  claim 48 , further comprising using the first processing solution for more than 8,000 Amp-minutes before changing out the first processing solution.  
   
   
       51 . The method of  claim 48 , further comprising plating material onto an ultra-thin seed layer while passing the electrical current between the inert electrode and the workpiece.  
   
   
       52 . The method of  claim 48 , further comprising plating material onto an ultra-thin seed layer and exposed portions of a barrier layer under the seed layer while passing the electrical current between the inert electrode and the workpiece.  
   
   
       53 . The method of  claim 48 , further comprising plating material directly onto a barrier layer while passing the electrical current between the inert electrode and the workpiece.  
   
   
       54 . The method of  claim 39  wherein the first processing solution comprises a catholyte and the second processing solution comprises an anolyte, and wherein the method further comprises using the second processing solution for a cycle period before changing out the second processing solution such that a desired conductivity and ion concentration gradient are maintained in the first processing solution.  
   
   
       55 . The method of  claim 39  wherein the first processing solution comprises a catholyte and the second processing solution comprises an anolyte, and wherein the method further comprises using the second processing solution for at least 400 Amp-minutes before changing out the second processing solution.