Electrochemical mechanical polishing apparatus conditioning method, and conditioning solution

Abstract

An electrochemical mechanical polishing apparatus is for use in polishing of a conductive material (e.g., metal) on a surface of a substrate by combination of electrochemical action and mechanical action. This apparatus includes a polishing table having divided electrodes and adapted to hold a polishing pad having a polishing surface, a polishing head adapted to hold a workpiece having a conductive film and to press the workpiece against the polishing surface, a second electrode for supplying an electric current to the conductive film, an electrolytic-solution supply section for supplying an electrolytic solution to the polishing surface, a detecting section adapted to detect a signal corresponding to a thickness of the conductive film, a variable resistance unit having the same number of variable resistors as the number of divided electrodes, a moving mechanism for providing relative movement between the workpiece and the polishing surface, and a control section adapted to control each of the variable resistors based on the signal from the detecting section.

1 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing table adapted to hold a polishing pad having a polishing surface, said polishing table having a first electrode including divided electrodes to be coupled to one of poles of a power source;   a polishing head adapted to hold a workpiece having a conductive film and to press the workpiece against the polishing surface;   a second electrode for supplying an electric current to the conductive film, said second electrode being coupled to another of the poles of the power source;   an electrolytic-solution supply section for supplying an electrolytic solution to the polishing surface;   a detecting section adapted to detect a signal corresponding to a thickness of the conductive film;   a variable resistance unit having the same number of variable resistors as the number of divided electrodes, said divided electrodes being coupled to the one of the poles of the power source via said variable resistors, respectively;   a moving mechanism for providing relative movement between the workpiece and the polishing surface; and   a control section adapted to control each of said variable resistors based on the signal from said detecting section.   
   
   
       2 . The electrochemical mechanical polishing apparatus according to  claim 1 , wherein
 each of said divided electrodes has a ring shape, and   said divided electrodes are arranged concentrically with a rotational center of said polishing table.   
   
   
       3 . The electrochemical mechanical polishing apparatus according to  claim 1 , wherein each of said variable resistors has a value of resistance that is variable in a range of 0.1 to 10 Ω. 
   
   
       4 . The electrochemical mechanical polishing apparatus according to  claim 1 , wherein said detecting section comprises an eddy current sensor. 
   
   
       5 . The electrochemical mechanical polishing apparatus according to  claim 1 , wherein said control section is operable to control a polishing rate of the conductive film such that a barrier film, underneath the conductive film, is exposed gradually from a central portion to a peripheral portion of the workpiece. 
   
   
       6 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing table adapted to hold a conductive polishing pad having a polishing surface, said polishing table having a first electrode coupled to one of poles of a power source;   a polishing head adapted to hold a workpiece having a conductive film and to press the workpiece against the polishing surface, said polishing head having a retainer ring shaped so as to surround a periphery of the workpiece;   a second electrode provided on said retainer ring so as to face the polishing pad and coupled to another of the poles of the power source, said second electrode being brought into contact with the polishing pad so as to supply an electric current to the conductive film via the polishing pad;   an electrolytic-solution supply section for supplying an electrolytic solution to the polishing surface; and   a moving mechanism for providing relative movement between the polishing pad and the workpiece held by said polishing head.   
   
   
       7 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing table adapted to hold a conductive polishing pad having a polishing surface, said polishing table having a first electrode coupled to one of poles of a power source;   a polishing head adapted to hold a workpiece having a conductive film and to press the workpiece against the polishing surface;   an electric-supply section having a second electrode coupled to another of the poles of the power source and arranged so as not to contact said polishing head, said second electrode being brought into surface contact with the polishing surface so as to supply an electric current to the conductive film via the polishing pad;   an electrolytic-solution supply section for supplying an electrolytic solution to the polishing surface; and   a moving mechanism for providing relative movement between the polishing pad and the workpiece held by said polishing head.   
   
   
       8 . The electrochemical mechanical polishing apparatus according to  claim 7 , further comprising a dresser operable to come into sliding contact with the polishing pad so as to dress the polishing pad, said electric-supply section being provided on said dresser. 
   
   
       9 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing table adapted to hold a conductive polishing pad having a polishing surface, said polishing table having a first electrode coupled to one of poles of a power source;   a polishing head adapted to hold a workpiece having a conductive film and to press the workpiece against the polishing surface;   an electric-supply section having a second electrode coupled to another of the poles of the power source, said second electrode being brought into contact with the polishing pad so as to supply an electric current to the conductive film via the polishing pad;   an electrolytic-solution supply section for supplying an electrolytic solution to the polishing surface; and   a moving mechanism for providing relative movement between the polishing pad and the workpiece held by said polishing head,   wherein said second electrode has a contact portion to be in contact with the polishing pad, and   the contact portion is movable relative to the polishing pad at a relative speed of not more than 0.1 m/s.   
   
   
       10 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing table adapted to hold a conductive polishing pad having a polishing surface, said polishing table having a first electrode coupled to one of poles of a power source;   a polishing head adapted to hold a workpiece having a conductive film and to press the workpiece against the polishing surface;   a second electrode coupled to another of the poles of the power source, said second electrode being brought into contact with the polishing pad so as to supply an electric current to the conductive film via the polishing pad;   an electrolytic-solution supply section for supplying an electrolytic solution to the polishing surface; and   a moving mechanism for providing relative movement between the polishing pad and the workpiece held by said polishing head,   wherein the polishing surface of the polishing pad has a non-contact area which does not contact the conductive film during polishing,   the polishing pad has through-holes therein, and   the non-contact area and at least a part of inner surfaces of the through-holes have been subjected to an insulating treatment.   
   
   
       11 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing pad having vertically-extending through-holes and having an upper surface serving as a polishing surface;   a polishing head adapted to press a substrate against said polishing surface;   a first electrode coupled to one of poles of a power source and arranged below said polishing pad;   a second electrode coupled to another of the poles of the power source and adapted to supply an electric current to a conductive film on the substrate;   an electrolytic-solution supply section for supplying an electrolytic solution to said polishing pad;   an electrolytic-solution path for directing an electrolytic solution, supplied from said electrolytic-solution supply section, to said through-holes from below said polishing pad; and   a moving mechanism for providing relative movement between said polishing pad and the substrate held by said polishing head.   
   
   
       12 . The electrochemical mechanical polishing apparatus according to  claim 11 , wherein
 said electrolytic-solution path includes:   an electrolytic-solution receiving section for receiving the electrolytic solution from said electrolytic-solution supply section;   communication holes configured to communicate respectively with said through-holes; and   communication grooves configured to communicate with said electrolytic-solution receiving section and to allow said communication holes to communicate with each other.   
   
   
       13 . The electrochemical mechanical polishing apparatus according to  claim 12 , wherein:
 said electrolytic-solution receiving section comprises an annular groove arranged concentrically with said polishing pad; and   said annular groove has a larger radius than a distance between a center of, said polishing pad and a circumferential surface of said polishing head in a polishing position.   
   
   
       14 . The electrochemical mechanical polishing apparatus according to  claim 11 , further comprising:
 a weir surrounding a circumferential surface of said polishing pad,   wherein said weir has an outer wall and an inner wall,   said outer wall has an upper end at a position higher than said polishing surface, and   said inner wall has an upper end at a position lower than said polishing surface.   
   
   
       15 . The electrochemical mechanical polishing apparatus according to  claim 11 , further comprising:
 a deformable liquid-permeable member surrounding a circumferential surface of said polishing pad; and   a liquid recovery section provided below said liquid-permeable member,   wherein said liquid-permeable member has an upper surface at a position higher than said polishing surface.   
   
   
       16 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing pad having vertically-extending through-holes and having an upper surface serving as a polishing surface;   at least one liquid-retaining member embedded in said polishing surface;   a polishing head adapted to press a substrate against said polishing surface;   a first electrode coupled to one of poles of a power source and arranged below said polishing pad;   a second electrode coupled to another of the poles of the power source and adapted to supply an electric current to a conductive film on the substrate;   an electrolytic-solution supply section for supplying an electrolytic solution to said polishing pad; and   a moving mechanism for providing relative movement between said polishing pad and the substrate held by said polishing head.   
   
   
       17 . The electrochemical mechanical polishing apparatus according to  claim 16 , wherein
 said at least one liquid-retaining member comprises plural liquid-retaining members disposed in said through-holes.   
   
   
       18 . The electrochemical mechanical polishing apparatus according to  claim 16 , wherein
 said liquid-retaining member is deformable, and   said liquid-retaining member has an upper surface at a position higher than said polishing surface.   
   
   
       19 . An electrochemical mechanical polishing apparatus, comprising:
 a polishing pad having vertically-extending through-holes and having an upper surface serving as a polishing surface;   a polishing head adapted to press a substrate against said polishing surface;   a first electrode coupled to one of poles of a power source and arranged below said polishing pad;   a second electrode coupled to another of the poles of the power source and adapted to supply an electric current to a conductive film on the substrate;   an electrolytic-solution supply section for supplying an electrolytic solution to said polishing pad; and   a moving mechanism for providing relative movement between said polishing pad and the substrate held by said polishing head,   wherein each of said through-holes has an upper opening with a smaller diameter than a diameter of a lower opening thereof.   
   
   
       20 . The electrochemical mechanical polishing apparatus according to  claim 19 , wherein
 a diameter of each of said through-holes is decreased gradually from said lower opening to said upper opening.   
   
   
       21 . The electrochemical mechanical polishing apparatus according to  claim 19 , wherein
 each of said through-holes comprises plural holes arranged vertically in series with different diameters.   
   
   
       22 . A method of conditioning a processing electrode and/or a polishing pad of an electrochemical mechanical polishing apparatus, said method comprising:
 polishing a conductive material of a workpiece by providing sliding contact between the conductive material and the polishing pad, which is arranged between the processing electrode and the conductive material, and by applying a voltage between the conductive material and the processing electrode in the presence of an electrolytic solution containing an organic acid and a corrosion inhibitor; and   before or after said polishing, conditioning the processing electrode and/or the polishing pad using a conditioning solution including components of the electrolytic solution other than the corrosion inhibitor.   
   
   
       23 . The method according to  claim 22 , wherein the conditioning solution further containing an oxidizing agent. 
   
   
       24 . The method according to  claim 22 , wherein the organic acid comprises at least one of acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, citric acid, aconitic acid, glyoxylic acid, glycolic acid, lactic acid, gluconic acid, malic acid, and tartaric acid. 
   
   
       25 . The method according to  claim 22 , wherein the organic acid comprises a strong acid having a sulfonic acid group. 
   
   
       26 . The method according to  claim 22 , wherein the strong acid having a sulfonic acid group comprises benzenesulfonic acid, methanesulfonic acid, taurine, cysteic acid, an alkylbenzene sulfonic acid having one to six carbons in an alkyl group, trifluoromethanesulfonic acid, and fluorosulfonic acid. 
   
   
       27 . A conditioning solution for use in conditioning a processing electrode and/or a polishing pad of an electrochemical mechanical polishing apparatus, said conditioning solution comprising:
 at least one organic acid or its salt; and   at least one strong acid having a sulfonic acid group,   wherein said conditioning solution does not contain a corrosion inhibitor.   
   
   
       28 . The conditioning solution according to  claim 27 , further comprising an oxidizing agent.