Apparatus and method for highly controlled electrodeposition

Abstract

An apparatus and method for highly controlled electrodeposition, particularly useful for electroplating submicron structures. Enhanced control of the process provides for a more uniform deposit thickness over the entire substrate, and permits reliable plating of submicron features. The apparatus includes a pressurized electrochemical cell to improve plating efficiency and reduce defects, vertical laminar flow of the electrolyte solution to remove surface gases from the vertically arranged substrate, a rotating wafer chuck to eliminate edge plating effects, and a variable aperture to control the current distribution and ensure deposit uniformity across the entire substrate. Also a dynamic profile anode whose shape can be varied to optimize the current distribution to the substrate. The anode is advantageously able to use metallic ion sources and may be placed close to the cathode thus minimizing contamination of the substrate.

What is claimed is:  
     
         1 . An apparatus for electrochemical deposition on a substrate, said apparatus comprising: 
 an anode;    a cathode with a vertical mounting surface;    a pressurized cell to contain electrolytic solution; and    an aperture disposed between said anode and said cathode;    wherein a vertical flow of said electrolytic solution is substantially laminar in a vicinity of said cathode.    
     
     
         2 . The apparatus of  claim 1  further comprising a reservoir.  
     
     
         3 . The apparatus of  claim 2  wherein the reservoir and cell comprise a closed system.  
     
     
         4 . The apparatus of  claim 2  further comprising at least one filter.  
     
     
         5 . The apparatus of  claim 4  wherein at least one of said at least one filter is a submicron filter.  
     
     
         6 . The apparatus of  claim 1  wherein the substrate comprises a semiconductor wafer.  
     
     
         7 . The apparatus of  claim 6  wherein the wafer is coated so that only certain features on the wafer receive the deposition.  
     
     
         8 . The apparatus of  claim 7  wherein said features are submicron features.  
     
     
         9 . The apparatus of  claim 1  wherein the cell is pressurized to at least approximately one atmosphere above ambient pressure.  
     
     
         10 . The apparatus of  claim 9  wherein the cell is pressurized to at least approximately two atmospheres above ambient pressure.  
     
     
         11 . The apparatus of  claim 1  wherein said cathode rotates about a horizontal axis perpendicular to said mounting surface.  
     
     
         12 . The apparatus of  claim 1  wherein said cell has a geometry that facilitates said laminar flow.  
     
     
         13 . The apparatus of  claim 12  wherein said cell comprises an inverted triangular or conical shape in a vicinity of an electrolyte inlet port.  
     
     
         14 . The apparatus of  claim 12  wherein said cell is of sufficient height to ensure that said flow is laminar in a vicinity of said cathode.  
     
     
         15 . The apparatus of  claim 1  wherein said aperture is electrically insulating.  
     
     
         16 . The apparatus of  claim 1  wherein said aperture comprises an opening.  
     
     
         17 . The apparatus of  claim 16  wherein said opening is circular.  
     
     
         18 . The apparatus of  claim 16  wherein a size of said opening is variable.  
     
     
         19 . The apparatus of  claim 18  wherein the size of said opening may be varied during operation of the cell.  
     
     
         20 . The apparatus of  claim 18  wherein said aperture comprises an iris.  
     
     
         21 . The apparatus of  claim 20  wherein said iris comprises at least three paddles.  
     
     
         22 . The apparatus of  claim 18  wherein the size of said opening is larger than a size of the substrate.  
     
     
         23 . The apparatus of  claim 18  wherein said opening can be completely closed.  
     
     
         24 . The apparatus of  claim 1  wherein said anode is situated less than approximately 5 cm from said cathode.  
     
     
         25 . The apparatus of  claim 24  wherein said anode is situated less than approximately 1 cm from said cathode.  
     
     
         26 . The apparatus of  claim 25  wherein said anode is situated less than approximately 0.5 cm from said cathode.  
     
     
         27 . The apparatus of  claim 1  wherein a metal ion source is situated behind said anode, thereby minimizing contamination from reaching the substrate while said anode retains a constant surface profile.  
     
     
         28 . The apparatus of  claim 1  wherein a surface profile of said anode is controllably variable.  
     
     
         29 . The apparatus of  claim 28  wherein said surface profile can be varied during operation of said cell.  
     
     
         30 . The apparatus of  claim 28  wherein said anode comprises parallel hollow electrically conducting tubes.  
     
     
         31 . The apparatus of  claim 1  further comprising a magnet.  
     
     
         32 . The apparatus of  claim 31  wherein said magnet comprises an electromagnet.  
     
     
         33 . The apparatus of  claim 31  wherein said magnet comprises at least one permanent magnet.  
     
     
         34 . The apparatus of  claim 31  wherein said magnet provides for codeposition of magnetic particles with electrochemical deposition on the substrate.  
     
     
         35 . The apparatus of  claim 34  wherein a strength of said magnet is adjusted to provide a desired concentration of magnetic particles on the substrate.  
     
     
         36 . An apparatus for performing multiple electrochemical depositions on a substrate, said apparatus comprising: 
 an anode having a variable surface profile;    a cathode with a vertical mounting surface;    a pressurized cell to contain electrolytic solution;    a closed system for circulation of the solution; and    an aperture with a variably sized opening disposed between said anode and said cathode;    wherein a vertical flow of said electrolytic solution is substantially laminar in a vicinity of said cathode.    
     
     
         37 . The apparatus of  claim 36  wherein the multiple depositions are carried out without opening said cell between each deposition.  
     
     
         38 . The apparatus of  claim 36  wherein said surface profile of said anode is controllably varied as desired for each deposition.  
     
     
         39 . The apparatus of  claim 36  wherein a size of said opening is varied as desired for each deposition.  
     
     
         40 . The apparatus of  claim 36  further comprising a filter.  
     
     
         41 . A method of electrolytically depositing a material on a substrate, the method comprising the steps of: 
 providing an electrolytic cell;    providing an anode;    mounting the substrate on a cathode so that a surface of the substrate is vertically disposed;    disposing an aperture between the anode and cathode;    providing laminar flow of electrolyte solution through a cell;    pressurizing the solution to a desired pressure; and    providing an electric potential difference between the cathode and the anode.    
     
     
         42 . The method of  claim 41  wherein the step of providing laminar flow comprises filtering the solution.  
     
     
         43 . The method of  claim 41  further comprising the step of uniformly plating submicron features on the substrate.  
     
     
         44 . The method of  claim 41  wherein the mounting step further comprises rotating the substrate about a horizontal axis perpendicular to the surface.  
     
     
         45 . The method of  claim 41  wherein the disposing step further comprises varying a size of an opening of the aperture.  
     
     
         46 . The method of  claim 41  wherein the step of providing an anode comprises situating the anode less than approximately 5 cm from the cathode.  
     
     
         47 . The method of  claim 46  wherein the step of providing an anode comprises situating the anode less than approximately 1 cm from the cathode.  
     
     
         48 . The method of  claim 47  wherein the step of providing an anode comprises situating the anode less than approximately 0.5 cm from the cathode.  
     
     
         49 . The method of  claim 41  wherein the step of providing an anode comprises situating the anode between a metallic ion source and the cathode.  
     
     
         50 . The method of  claim 49  wherein the step of providing an anode comprises minimizing contamination from reaching the cathode while retaining a constant surface profile.  
     
     
         51 . The method of  claim 41  wherein the step of providing an anode comprises controllably varying a surface profile of the anode.  
     
     
         52 . The method of  claim 41  wherein the mounting step further comprises providing a magnetic field.  
     
     
         53 . The method of  claim 52  further comprising the step of using the magnetic field to codeposit magnetic particles with the material on the substrate.  
     
     
         54 . The method of  claim 53  further comprising varying the magnetic field to adjust the composition of the magnetic particles on the substrate.  
     
     
         55 . A method of performing multiple electrolytic depositions on a substrate, the method comprising the steps of: 
 a. providing a pressurized electrolytic cell;    b. providing an aperture with a variably sized opening;    c. optimizing deposition parameters of the cell including a pressure of the cell and a size of the opening for a desired deposition;    d. depositing a material on a substrate; and    e. repeating steps (a) through (d) without opening the cell.    
     
     
         56 . An anode for use in an electrochemical process, said anode comprising: 
 a plurality of parallel hollow electrically conducting tubes with sides in slideable contact with one another; and    a clamp circumferentially disposed around the plurality of tubes to prevent motion of the tubes.    
     
     
         57 . The anode of  claim 56  wherein the tubes are cylindrical.  
     
     
         58 . The anode of  claim 56  wherein the tubes have a cross section comprising a regular polygon.  
     
     
         59 . The anode of  claim 56  wherein a surface profile of the anode comprises positions of ends of each of the tubes which face a cathode.  
     
     
         60 . The anode of  claim 59  wherein the surface profile is adjustable by sliding the tubes relative to one another.  
     
     
         61 . The anode of  claim 56  wherein a shape of the surface profile is selected from the group consisting of flat, convex, hemispherical, conical, domed, curved, and pyramidal.  
     
     
         62 . The anode of  claim 56  comprising an electrically conducting material.  
     
     
         63 . The anode of  claim 56  comprising a soluble material.  
     
     
         64 . The anode of  claim 56  comprising an insoluble material.  
     
     
         65 . The anode of  claim 64  comprising a platinumized material.  
     
     
         66 . The anode of  claim 56  further comprising a receptacle for placement of an electrochemical ionic source media.  
     
     
         67 . The anode of  claim 66  wherein the media is a metallic ion source.  
     
     
         68 . The anode of  claim 66  wherein the receptacle is on a side of the anode opposite the surface profile.  
     
     
         69 . The anode of  claim 68  wherein the anode minimizes contamination from reaching a cathode while retaining a constant surface profile.  
     
     
         70 . The anode of  claim 56  wherein the process is selected from the group consisting of plating, electroplating, electrodeposition, chemical and mechanical polishing (CMP), electropolishing, etching, and electrolysis.