Apparatus and method of evaluating electroplating solutions and conditions

Abstract

The present invention generally relates to an apparatus and method of evaluating electroplating solutions and conditions. In one embodiment, the method of evaluating electroplating solutions comprises utilizing an electrochemical measuring cell having a working electrode having a lid with at least one hole, a counter electrode, and a reference electrode. The working electrode, the counter electrode, and the reference electrode are immersed in at least one sample of at least one electroplating solution. The lid is disposed over the working electrode forming a chamber between the working electrode and the lid. The lid further has a hole to allow an electroplating solution to flow into the chamber and reach the working electrode. The potential of the working electrode in the sample of the electroplating solution is measured over time with a constant current supplied to the working electrode. The electrochemical measurements may be used to determine which solutions are capable of bottom-up filling and may be used to estimate the optimal electroplating parameters. In still another embodiment, the present invention relates to an apparatus for electroplating a substrate comprises a chamber body, an anode disposed in the chamber body, a contact ring disposed in the chamber body, one or more power supplies coupled to the anode and the contact ring, and an electrochemical measuring cell disposed in the chamber body or coupled to an electrolyte output coupled to the chamber body.

1 . Method of evaluating an electroplating solution, comprising: 
 immersing a working electrode, a counter electrode, and a reference electrode in a sample of an electroplating solution;    measuring a potential of the working electrode in the sample of the electroplating solution over time with a constant current supplied to the working electrode; and    identifying whether the electroplating solution is capable of obtaining bottom-up growth at the constant current in a feature of a substrate.    
     
     
         2 . The method of  claim 1 , wherein identifying whether the electroplating solution is capable of obtaining bottom-up growth at the constant current in a feature of a substrate comprises determining whether the potential of the working electrode over time exhibits a relative minimum at the constant current.  
     
     
         3 . The method of  claim 2 , further comprising estimating a time to initiate bottom-up growth in the feature from the relative minimum.  
     
     
         4 . The method of  claim 1 , wherein the electroplating solution comprises inhibitors and accelerators.  
     
     
         5 . The method of  claim 1 , wherein measuring the potential of the working electrode comprises utilizing a lid disposed over the working electrode, the lid forming a chamber between the working electrode and the lid, and the lid having at least one hole formed therethrough.  
     
     
         6 . The method of  claim 5 , wherein the chamber has a volume of less than about 100 mm 2  and the at least one hole has a total combined cross-sectional area equal to or less than about 30% of an exposed area of the working electrode.  
     
     
         7 . Method of evaluating an electroplating solution, comprising: 
 immersing a working electrode, a counter electrode, and a reference electrode in a sample of an electroplating solution;    measuring a potential of the working electrode in the sample of the electroplating solution over time with a constant current supplied to the working electrode; and    determining whether the potential of the working electrode over time exhibits a relative minimum at the constant current.    
     
     
         8 . The method of  claim 7 , wherein the electroplating solution comprises inhibitors and accelerators.  
     
     
         9 . The method of  claim 7 , wherein measuring the potential of the working electrode comprises utilizing a lid disposed over the working electrode, the lid forming a chamber between the working electrode and the lid, and the lid having at least one hole formed therethrough.  
     
     
         10 . The method of  claim 9 , wherein the chamber has a volume of less than about 100 mm 2  and the at least one hole has a total combined cross-sectional area equal to or less than about 30% of an exposed area of the working electrode.  
     
     
         11 . Method of evaluating an electroplating solution, comprising: 
 immersing a working electrode, a counter electrode, and a reference electrode in a sample of an electroplating solution, the electroplating solution comprising inhibitors and accelerators;    measuring a potential of the working electrode in the sample of the electroplating solution over time with a constant current supplied to the working electrode by utilizing a lid disposed over the working electrode, the lid forming a chamber between the working electrode and the lid, the lid having at least one hole formed therethrough, the chamber having a volume of less than about 100 mm 2  and the at least one hole having a total combined cross-sectional area equal to or less than about 30% of an exposed area of the working electrode; and    determining whether the potential of the working electrode over time exhibits a relative minimum at the constant current.    
     
     
         12 . Method of evaluating an electroplating solution, comprising: 
 performing a plurality of trials, each trial comprising: 
 immersing a working electrode, a counter electrode, and a reference electrode in a sample of an electroplating solution;  
 measuring a potential of the working electrode in the sample of the electroplating solution over time with a constant current supplied to the working electrode; and  
 identifying whether the electroplating solution is capable of obtaining bottom-up growth at the constant current in a feature of a substrate.  
   
     
     
         13 . The method of  claim 12 , wherein performing a plurality of trials comprises evaluating a plurality of electroplating solutions at the same constant current.  
     
     
         14 . The method of  claim 12 , wherein performing a plurality of trials comprises evaluating one electroplating solution at a plurality of constant currents.  
     
     
         15 . The method of  claim 12 , wherein performing a plurality of trials comprises evaluating a plurality of electroplating solutions at a plurality of constant currents.  
     
     
         16 . The method of  claim 12 , wherein performing a plurality of trials comprises evaluating at least one electroplating solution at one or more constant currents at a plurality of temperatures.  
     
     
         17 . The method of  claim 12 , wherein identifying whether the electroplating solution is capable of obtaining bottom-up growth at the constant current in a feature of a substrate comprises determining whether the potential of the working electrode over time exhibits a relative minimum at the constant current.  
     
     
         18 . The method of  claim 17 , further comprising estimating a time to initiate bottom-up growth in the feature from the relative minimum.  
     
     
         19 . The method of  claim 17 , further comprising comparing the slopes of the potentials of the trials which exhibit a relative minimum to determine a relative rate of bottom-up growth.  
     
     
         20 . The method of  claim 12 , wherein the electroplating solution comprises inhibitors and accelerators.  
     
     
         21 . Apparatus for evaluating electroplating solutions, comprising: 
 a working electrode;    a lid disposed over the working electrode and forming a chamber between the working electrode and the lid, the lid having at least one hole formed therethrough;    a counter electrode;    a reference electrode;    a galvanostat coupled to the working electrode and the counter electrode; and    a voltmeter coupled to the working electrode and the reference electrode.    
     
     
         22 . The apparatus of  claim 21 , wherein the lid has a bottom wall and a sidewall, the at least one hole being disposed in the bottom wall.  
     
     
         23 . The apparatus of  claim 21 , wherein the lid has a bottom wall and a sidewall, the at least one hole being disposed in the sidewall.  
     
     
         24 . The apparatus of  claim 21 , wherein the lid is removable.  
     
     
         25 . The apparatus of  claim 21 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 30% of an exposed area of the working electrode.  
     
     
         26 . The apparatus of  claim 21 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 10% of an exposed area of the working electrode.  
     
     
         27 . The apparatus of  claim 21 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 0.8 mm 2 .  
     
     
         28 . The apparatus of  claim 21 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 0.1 mm 2 .  
     
     
         29 . The apparatus of  claim 21 , wherein the chamber has a volume of less than about 100 mm 3 .  
     
     
         30 . The apparatus of  claim 21 , wherein the at least one hole comprises a single hole.  
     
     
         31 . The apparatus of  claim 21 , wherein the at least one hole comprises a plurality of holes.  
     
     
         32 . The apparatus of  claim 21 , wherein the at least one hole comprises a porous membrane.  
     
     
         33 . Apparatus for evaluating electroplating solutions, comprising: 
 a working electrode;    a lid disposed over the working electrode, the lid comprising at least one hole; and    a chamber formed between the working electrode and the lid.    
     
     
         34 . The apparatus of  claim 33 , wherein the lid has a bottom wall and a sidewall, the at least one hole being disposed in the bottom wall.  
     
     
         35 . The apparatus of  claim 33 , wherein the lid has a bottom wall and a sidewall, the at least one hole being disposed in the sidewall.  
     
     
         36 . The apparatus of  claim 33 , wherein the lid is removable.  
     
     
         37 . The apparatus of  claim 33 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 30% of an exposed area of the working electrode.  
     
     
         38 . The apparatus of  claim 33 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 10% of an exposed area of the working electrode.  
     
     
         39 . The apparatus of  claim 33 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 0.8 mm 2 .  
     
     
         40 . The apparatus of  claim 33 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 0.1 mm 2 .  
     
     
         41 . The apparatus of  claim 33 , wherein the chamber has a volume of less than about 100 mm 3 .  
     
     
         42 . The apparatus of  claim 33 , wherein the at least one hole comprises a single hole.  
     
     
         43 . The apparatus of  claim 33 , wherein the at least one hole comprises a plurality of holes.  
     
     
         44 . The apparatus of  claim 33 , wherein the at least one hole comprises a porous membrane.  
     
     
         45 . An apparatus for electroplating a substrate; comprising: 
 a chamber body;    an anode disposed in the chamber body;    a contact ring disposed in the chamber body;    one or more power supplies coupled to the anode and the contact ring; and    an electrochemical measuring cell having a working electrode, a counter electrode, and a reference electrode.    
     
     
         46 . The apparatus of  claim 45 , wherein the electrochemical measuring cell is disposed in the chamber body.  
     
     
         47 . The apparatus of  claim 46 , wherein the electrochemical measuring cell is disposed in the chamber body outside a flow of electroplating solution from the anode to the contact ring.  
     
     
         48 . The apparatus of  claim 45 , further comprising an electrolyte output coupled to the chamber body, the electrochemical measuring cell being coupled to the electrolyte output.  
     
     
         49 . The apparatus of  claim 45 , further comprising: 
 an electrolyte input supply coupled to the chamber body; and    a controller coupled to the electrochemical measuring cell and the electrolyte input supply.    
     
     
         50 . The apparatus of  claim 49 , wherein the controller is adapted to control the electrolyte input supply to add a chemical solution to the chamber body.  
     
     
         51 . The apparatus of  claim 50 , wherein the electrolyte input supply is a regeneration element adapted to recirculate electroplating solution to the chamber body.  
     
     
         52 . The apparatus of  claim 45 , further including a galvanostat coupled to the working electrode and the counter electrode of the electrochemical measuring cell and a voltmeter coupled to the working electrode and the reference electrode of the electrochemical measuring cell.  
     
     
         53 . The apparatus of  claim 45 , wherein the electrochemical measuring cell has a lid disposed over the working electrode and forming a chamber between the working electrode and the lid, the lid having at least one hole formed therethrough.  
     
     
         54 . The apparatus of  claim 53 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 30% of an exposed area of the working electrode.  
     
     
         55 . The apparatus of  claim 53 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 10% of an exposed area of the working electrode.  
     
     
         56 . The apparatus of  claim 53 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 0.8 mm 2 .  
     
     
         57 . The apparatus of  claim 53 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 0.1 mm 2 .  
     
     
         58 . The apparatus of  claim 53 , wherein the chamber has a volume of less than about 100 mm 3 .  
     
     
         59 . The apparatus of  claim 53 , wherein the at least one hole comprises a single hole.  
     
     
         60 . The apparatus of  claim 53 , wherein the at least one hole comprises a plurality of holes.  
     
     
         61 . The apparatus of  claim 53 , wherein the at least one hole comprises a porous membrane.  
     
     
         62 . An apparatus for electroplating a substrate; comprising: 
 a chamber body;    an anode disposed in the chamber body;    a contact ring disposed in the chamber body;    one or more power supplies coupled to the anode and the contact ring; and    an electrochemical measuring cell having a working electrode, a counter electrode, a reference electrode, and a lid disposed over the working electrode,    wherein the lid forms a chamber between the working electrode and the lid, and the lid has at least one hole having a total combined cross-sectional area equal to or less than about 30% of an exposed area of the working electrode formed therethrough.    
     
     
         63 . The apparatus of  claim 62 , wherein the at least one hole has a total combined cross-sectional area equal to or less than about 10% of an exposed area of the working electrode.  
     
     
         64 . The apparatus of  claim 62 , wherein the chamber has a volume of less than about 100 mm 3 .  
     
     
         65 . The apparatus of  claim 62 , wherein the at least one hole comprises a single hole.  
     
     
         66 . The apparatus of  claim 62 , wherein the at least one hole comprises a plurality of holes.  
     
     
         67 . The apparatus of  claim 62 , wherein the at least one hole comprises a porous membrane.  
     
     
         68 . An apparatus for electroplating a substrate; comprising: 
 a chamber body;    an anode disposed in the chamber body;    a contact ring disposed in the chamber body;    one or more power supplies coupled to the anode and the contact ring;    an electrolyte input supply coupled to the chamber body,    an electrochemical measuring cell having a working electrode, a counter electrode, and a reference electrode, and    a controller coupled to the electrochemical measuring cell and the electrolyte input supply.    
     
     
         69 . The apparatus of  claim 68 , wherein the controller is adapted to control the electrolyte input supply to add a chemical solution to the chamber body.  
     
     
         70 . The apparatus of  claim 69 , wherein the electrolyte input supply is a regeneration element adapted to recirculate electroplating solution to the chamber body  
     
     
         71 . A method of evaluating an electroplating solution, comprising: 
 contacting an electrochemical measuring cell with an electroplating solution of an electroplating chamber, the electrochemical measuring cell comprising a working electrode, a counter electrode, and a reference electrode; and    measuring a potential of the working electrode over time with a constant current supplied to the working electrode to provide a potential trace.    
     
     
         72 . The method of  claim 71 , wherein contacting the electrochemical measuring cell with the electroplating solution comprises disposing the electrochemical measuring cell within a chamber body of the electroplating chamber.  
     
     
         73 . The method of  claim 71 , wherein contacting the electrochemical measuring cell with the electroplating solution comprises coupling the electrochemical measuring cell to an electrolyte output of the electroplating chamber.  
     
     
         74 . The method of  claim 71 , further comprising evaluating the potential trace.  
     
     
         75 . The method of  claim 74 , wherein evaluating the potential trace comprises determining whether the potential trace exhibits a relative minimum.  
     
     
         76 . The method of  claim 75 , wherein evaluating the potential trace further comprises determining a time interval when the relative minimum occurs.  
     
     
         77 . The method of  claim 74 , wherein evaluating the potential trace comprises evaluating the slope of the potential trace.  
     
     
         78 . The method of  claim 74 , wherein evaluating the potential trace comprises comparing the potential to at least one other potential trace.  
     
     
         79 . The method of  claim 71 , further comprising adding a chemical solution to the electroplating chamber based upon the potential trace.  
     
     
         80 . The method of  claim 79 , wherein adding the chemical solution to the electroplating chamber is automatically performed by a controller coupled to the electrochemical measuring cell.  
     
     
         81 . The method of  claim 71 , wherein the electroplating solution comprises inhibitors and accelerators.  
     
     
         82 . A method of evaluating an electroplating solution, comprising: 
 contacting an electrochemical measuring cell with an electroplating solution of an electroplating chamber, the electrochemical measuring cell comprising a working electrode, a counter electrode, and a reference electrode;    measuring a potential of the working electrode over time with a constant current supplied to the working electrode to provide a potential trace; and    and adding a chemical solution to the electroplating chamber based upon the potential trace.    
     
     
         83 . The method of  claim 82 , wherein adding the chemical solution to the electroplating chamber is automatically performed by a controller coupled to the electrochemical measuring cell.  
     
     
         84 . The method of  claim 82 , wherein the electroplating solution comprises inhibitors and accelerators.