Method of stabilizing additive concentrations in an electroplating bath for interconnect formation

Abstract

Embodiments of the invention may further provide an electrochemical plating cell. The cell includes a fluid basin configured to contain an electrolyte plating solution, a fluid tank in fluid communication with the fluid basin and being configured to supply the electrolyte plating solution thereto, and an electrolyte solution stabilization device in fluid communication with the fluid tank. The stabilization device includes a fluid container having a fluid inlet and a fluid outlet, and an absorbent material positioned in the fluid container in a fluid path between the fluid inlet and the fluid outlet, wherein the absorbent material is configured to leach a solution additive into the electrolyte plating solution to maintain the solution additive within a processing window during an electrochemical plating process.

1 . A method for controlling additive concentration in an electrochemical plating cell, comprising: 
 saturating an absorbent material positioned in a container having a fluid inlet and a fluid outlet with a solution additive;    leaching the solution additive into the electrochemical plating solution when a concentration of the additive in the electrochemical plating solution falls below a predetermined concentration; and    absorbing the solution additive from the electrochemical plating solution when the concentration of the additive increases above the predetermined concentration.    
   
   
       2 . The method of  claim 1 , wherein the absorbent material comprises at least one of charcoal, polypropylene, glass, minerals, ion-exchange resins, resins for chromatography, and combinations thereof.  
   
   
       3 . The method of  claim 2 , comprising positioning the container in a fluid conduit between the electrochemical plating cell and a fluid supply tank.  
   
   
       4 . The method of  claim 2 , comprising positioning the container in a fluid supply tank in fluid communication with the electrochemical plating cell.  
   
   
       5 . The method of  claim 3 , further comprising filtering the electrochemical plating solution between the container and the fluid supply tank.  
   
   
       6 . A method for maintaining an additive concentration in an electrochemical plating solution within a processing window, comprising: 
 positioning a container having a fluid inlet and a fluid outlet in fluid communication with a fluid conduit connecting a plating cell and a fluid supply tank;    saturating an absorbent material positioned in an interior of the container with the additive;    dispensing the additive from the absorbent material into the electrochemical plating solution when a concentration of the additive in the plating solution is below a desired concentration; and    absorbing the additive from the plating solution into the absorbent material when the concentration of the additive in the plating solution is above the desired concentration.    
   
   
       7 . The method of  claim 6 , wherein the absorbent material comprises charcoal.  
   
   
       8 . The method of  claim 6 , wherein the absorbent material comprises polypropylene, glass, minerals, ion-exchange resins, resins for chromatography, or combinations thereof.  
   
   
       9 . The method of  claim 7 , wherein the container comprises a column.  
   
   
       10 . The method of  claim 7 , further comprising filtering fluid exiting the fluid outlet for particulate matter.  
   
   
       11 . The method of  6 , further comprising positioning the container in a lower portion of the fluid supply tank.  
   
   
       12 . The method of  claim 6 , wherein the dispensing comprises leaching the additive contained in the absorbent material in proportion to a fluid flow through the absorbent material.  
   
   
       13 . The method of  claim 6 , wherein the dispensing comprises leaching the additive contained in the absorbent material in proportion to fluid pressure supplied to the container.  
   
   
       14 . A method of electrochemically plating a layer on a substrate, comprising: 
 providing an electrolyte having a solution additive;    providing an electrochemical plating cell assembly that comprises: 
 an electrochemical plating cell;  
 a fluid circulation loop that comprises: 
 an electrolyte supply tank; and  
 a pump that is adapted to cause the electrolyte to flow between the electrolyte supply tank and the electrochemical plating cell; and  
 
 an absorbent material that is in fluid communication with the electrolyte positioned in the fluid circulation loop, wherein the absorbent material is adapted to absorb and leach the solution additive to stabilize the concentration of the solution additive in the electrolyte; and  
   depositing a layer on a substrate that is in fluid contact with the electrolyte that is positioned in the electrochemical plating cell.    
   
   
       15 . The method of  claim 14 , wherein the absorbent material comprises charcoal.  
   
   
       16 . The method of  claim 14 , wherein the absorbent material comprises polypropylene, glass, minerals, ion-exchange resins, resins for chromatography, or combinations thereof.  
   
   
       17 . The method of  claim 14 , wherein the absorbent material is positioned in a fluid conduit that fluidly connects the electrolyte supply tank to the electrochemical plating cell.  
   
   
       18 . The method of  14 , wherein the absorbent material is positioned in the electrolyte supply tank.  
   
   
       19 . The method of  claim 14 , wherein the solution additive is an organic material selected from a group consisting of levelers, suppressors, accelerators, and combinations thereof.  
   
   
       20 . The method of  claim 14 , wherein the electrolyte-to-absorbent volume ratio is between about 1:1 and about 100:1.