Aug. 7, 2008  5  US 2008/0188162 Al  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 mis.  [0046]  The second electrode may have a roller as the con› tact portion (an electric supply contact). In this case, a rota› tional speed (a linear velocity of rotation) of the roller and a  rotational speed of the polishing pad are adjusted such that a  relative speed between the roller and the rotating pad is zero,  for example. Alternatively, the roller may be rotatably sup› ported with its rotational friction being nearly zero, so that the  roller can be rotated by friction between the roller and the  polishing pad. These structures can reduce the friction  between the electric supply contact (roller) and the polishing  pad, and can thus prevent the polishing pad from being dam› aged and removed from the polishing table. Because the  damage to the polishing pad is prevented, reliable current  supply can be secured without deteriorating polishing prop› erties.  [0047]  Another aspect of the present invention is an elec› trochemical mechanical polishing apparatus including: a pol› ishing table adapted to hold a conductive polishing pad hav› ing a polishing surface, the polishing table having a first  electrode coupled to one of poles of a power source; a pol› ishing 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, the 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 work› piece held by the polishing head. 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. The non-contact area and at least a part  of inner surfaces of the through-holes have been subjected to  an insulating treatment.  [0048]  Since the non-contact area and the inner surface of  the through-holes of the conductive polishing pad, which may  be made of mainly carbon, have been subjected insulating  treatment, an electrolytic reaction at the surface of the pol› ishing pad ( conductive pad) can be minimized. Therefore,  formation of pits in the surface of the conductive film and a  drop in polishing rate due to oxygen generated at the surface  of the polishing pad can be prevented.  [0049]  Usable methods of insulating part of the conductive  polishing pad include an insulating coating treatment and a  surface modification treatment. Examples of such an insulat› ing coating treatment include coating of a surface with an ink,  a paint, an adhesive, or the like. Examples of the surface  modification treatment include modifying of a surface by  means of a chemical treatment, graft polymerization, irradia› tion with a light, an electron beam or an ion beam, a plasma  treatment, or plating.  [0050]  According to the present invention, the surface of  the conductive film ( e.g., a copper film on a surface of a  substrate) is not damaged, and reliable supply of an electric  current can be performed with a uniform electric potential  being provided over the surface of the conductive film, even  when a rotary type is employed. Further, because the non› contact area (i.e., an area which is not used for polishing) of  the conductive polishing pad is covered with the insulating  material, an electrolytic reaction (production of oxygen) on  the surface of the polishing pad can be minimized. As a result,  production of a defect in the conductive film during polishing  can be suppressed.  [0051]  Another aspect of the present invention is an elec› trochemical mechanical polishing apparatus including: a pol› ishing 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 the pol› ishing surface; a first electrode coupled to one of poles of a  power source and arranged below the 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 the polishing pad; an  electrolytic-solution path for directing an electrolytic solu› tion, supplied from the electrolytic-solution supply section, to  the through-holes from below the polishing pad; and a mov› ing mechanism for providing relative movement between the  polishing pad and the substrate held by the polishing head.  [0052]  In a preferred aspect of the present invention, the  electrolytic-solution path includes: an electrolytic-solution  receiving section for receiving the electrolytic solution from  the electrolytic-solution supply section; communication  holes configured to communicate respectively with the  through-holes; and communication grooves configured to  communicate with the electrolytic-solution receiving section  and to allow the communication holes to communicate with  each other.  [0053]  In a preferred aspect of the present invention, the  electrolytic-solution receiving section comprises an annular  groove arranged concentrically with the polishing pad; and  the annular groove has a larger radius than a distance between  a center of the polishing pad and a circumferential surface of  the polishing head in a polishing position.  [0054]  In a preferred aspect of the present invention, the  electrochemical mechanical polishing apparatus further  includes a weir surrounding a circumferential surface of the  polishing pad. The weir has an outer wall and an inner wall,  the outer wall has an upper end at a position higher than the  polishing surface, and the inner wall has an upper end at a  position lower than the polishing surface.  [0055]  In a preferred aspect of the present invention, the  electrochemical mechanical polishing apparatus further  includes: a deformable liquid-permeable member surround› ing a circumferential surface of the polishing pad; and a liquid  recovery section provided below the liquid-permeable mem› ber. The liquid-permeable member has an upper surface at a  position higher than the polishing surface.  [0056]  Another aspect of the present invention is an elec› trochemical mechanical polishing apparatus including: a pol› ishing pad having vertically-extending through-holes and  having an upper surface serving as a polishing surface; at least  one liquid-retaining member embedded in the polishing sur› face; a polishing head adapted to press a substrate against the  polishing surface; a first electrode coupled to one of poles of  a power source and arranged below the polishing pad; a  second electrode coupled to another of the poles of the power  source and adapted to supply an electric current to a conduc› tive film on the substrate; an electrolytic-solution supply sec› tion for supplying an electrolytic solution to the polishing  pad; and a moving mechanism for providing relative move› ment between the polishing pad and the substrate held by the  polishing head. 