Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B53/00—Devices or means for dressing or conditioning abrasive surfaces
  • B24B53/017—Devices or means for dressing, cleaning or otherwise conditioning lapping tools
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B53/00—Devices or means for dressing or conditioning abrasive surfaces
  • B24B53/001—Devices or means for dressing or conditioning abrasive surfaces involving the use of electric current
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P52/00—Grinding, lapping or polishing of wafers, substrates or parts of devices

Definitions

• the present disclosure relates broadly to pad conditioners for chemical mechanical planarization of semiconductor wafers and methods of their use.
• CMP Chemical Mechanical Planarization
• polishing/material-removal process in which a polishing pad and a polishing slurry are used.
• the polishing slurry is often corrosive. Due to glazing, the material removal efficiency of polishing pads usually declines after prolonged use.
• a pad conditioner is used to unglaze (i.e., condition) the polishing pad.
• microscratching i.e., micrometer scale scratches
• over-polishing i.e., micrometer scale scratches
• dishing Main contributors to microscratching include abrasive particles from the slurry, loose materials from polishing, loose diamonds from pad conditioners, and metal particles from the pad conditioner.
• some metals such as, for example, nickel may pose a contamination issue.
• embedded nickel particles in the wafer surface may result in shifts in electrical or reliability performance of active/passive devices and interconnects.
• MOSFET metal-oxide-semiconductor field-effect transistor
• copper interconnects can become electrical short circuited when nickel contamination causes electrical bridging between separate copper traces.
• the present disclosure provides a cathodically-protected pad conditioner for chemical mechanical planarization comprising: an abrasive member comprising a metallic substrate having an abrasive surface and a back surface opposite the abrasive surface, wherein the abrasive surface comprises abrasive particles affixed to the metallic substrate;
• a support carrier having a receiving surface and a peripheral edge adjacent the receiving surface, wherein the receiving surface is affixed and adjacent to the back surface of the abrasive member;
• a cathodic protection circuit configured to provide a cathodic protection current from the anode to the metallic substrate if contacted with an electrolyte solution.
• the cathodic protection circuit comprises an electric cell having positive and negative terminals, wherein the positive terminal is electrically coupled to the anode, and wherein the negative terminal is electrically coupled to the metallic substrate.
• the electric cell is at least partially disposed within a cavity in the support carrier.
• the negative terminal is at least partially affixed to the metallic substrate by conductive adhesive.
• the peripheral edge has a beveled portion adjacent the abrasive member, and the anode is disposed on the beveled portion.
• cathodically-protected pad conditioners according to the present disclosure are inhibited with respect to oxidation of the metallic substrate during chemical mechanical planarization of a semiconductor wafer that may result in microscratches on, and/or contamination of, the semiconductor wafer.
• Pad conditioners according to the present disclosure are useful, for example, for use during chemical mechanical planarization of a semiconductor wafer. Accordingly, in another aspect, the present disclosure provides a method of conditioning a pad, the method comprising using a pad conditioner according to the present disclosure during chemical mechanical planarization of a semiconductor wafer. In some embodiments, the cathodically-protected pad conditioner contacts the pad during chemical mechanical planarization of a semiconductor wafer.
• the foregoing embodiments may be implemented in any combination thereof, unless such combination is clearly erroneous in view of the teachings of the present disclosure. The features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.
• FIG. 1 is a perspective view of an exemplary pad conditioner 100 according to one embodiment of the present disclosure
• FIG. 2 is a cross-sectional side view of pad conditioner 100 shown in FIG. 1;
• FIG. 3 is a schematic top view of an exemplary pad conditioner 200;
• FIG. 4 is a schematic top view of an exemplary pad conditioner 300.
• exemplary cathodically-protected pad conditioner 100 for chemical mechanical planarization comprises abrasive member 110, support carrier 120, anode 130, and cathodic protection circuit 140.
• Abrasive member 110 comprises metallic substrate 112 which has abrasive surface 114 and back surface 116 opposite abrasive surface 114.
• Abrasive surface 114 comprises abrasive particles 118 affixed to metallic substrate 112.
• Support carrier 120 has receiving surface 122 and peripheral edge 124 adjacent to receiving surface 122.
• Receiving surface 122 is affixed and adjacent to back surface 116 of abrasive member 110 by layer of conductive adhesive 119.
• Anode 130 is affixed to peripheral edge 124.
• Cathodic protection circuit 140 is configured to provide a cathodic protection current from anode 130 to metallic substrate 112 if contacted with an electrolyte solution.
• the metallic substrate includes one or more metals and/or metal alloys, and may include a brazing alloy around the abrasive particles.
• suitable metals include stainless steel, chromium, titanium, titanium alloys, zirconium, zirconium alloys, nickel, and alloys thereof.
• the substrate may be formed by any suitable process including, for example, brazing or electroplating (e.g. of nickel).
• Exemplary nickel alloys include a nickel alloy including about 80 percent nickel and about 20 percent chrome.
• the metallic substrate may be rigid, semi-rigid, or flexible, and may be relatively thin (e.g., a foil) or thick, as desired.
• the abrasive member can be formed, for example, by sintering a matrix material formed into an appropriate shape (e.g., a disc) with abrasive particles disposed on a major surface of the matrix material.
• the matrix material comprises a brazing alloy and a sintered corrosion resistant metallic powder. When heated to a predetermined temperature, the brazing alloy becomes liquid and flows around the abrasive particles. In addition, the brazing alloy reacts with and forms a chemical bond with the abrasive particles. In order to form the chemical bond, the composition of the brazing alloy includes an element known to react with the particular abrasive particle, thereby forming the chemical bond.
• the brazing alloy may include at least one of the following elements which may react and form a chemical bond with the diamond: chromium, tungsten, cobalt, titanium, zinc, iron, manganese, or silicon.
• the brazing alloy may include at least one of aluminum, boron, carbon and silicon which may form the chemical bond with the abrasive particles
• the brazing alloy may include at least one of aluminum, boron, carbon, and silicon. It will be recognized, however, that the brazing alloy may also contain various inert elements in addition to the element or elements which react with and form the chemical bond with the abrasive particles.
• Exemplary abrasive particles include abrasive particles having a Mohs hardness of at least 8 and, more typically, at least 9.
• Suitable abrasive particles include, for example, fused aluminum oxide, ceramic aluminum oxide, heat treated aluminum oxide, silicon carbide, boron carbide, tungsten carbide, alumina zirconia, iron oxide, diamond (natural and synthetic), ceria, cubic boron nitride (CBN), diamond, garnet, carborundum, boron suboxide, and combinations thereof.
• the abrasive particles may further include a surface treatment or coating, such as a coupling agent or a metal or ceramic coating.
• Abrasive particles useful in the present disclosure typically have an average size in a range of from 20 to 1000 micrometers, although other sizes may also be used. More typically, the abrasive particles have an average size of about 45 to 625 micrometers, or about 75 to 300 micrometers.
• the abrasive member is shaped as a disk or annulus or portion thereof, although other shapes may also be used. If multiple abrasive members are mounted on the support carrier, it is desirable that a respective cathodic protection circuit be present for each abrasive member. A portion of the abrasive surface, typically adjacent the edge of the disk, may be substantially free of abrasive particles. Exemplary abrasive disks suitable for use as the abrasive member are also described in U.S. Patent Nos. 5,620,489 (Tselesin) and 6,123,612 (Goers).
• the abrasive member is affixed to the support carrier such that the abrasive surface of the abrasive member is exposed and available for abrading.
• the support carrier is adapted to be mountable in a CMP apparatus, with variations in shape and size being dependent on the equipment to be used.
• the support carrier is substantially disk-shaped, although this is not a requirement.
• the support carrier has a receiving surface and a peripheral edge.
• the peripheral edge includes a beveled portion.
• the support carrier may be formed of, for example, synthetic polymeric materials (e.g., plastics or thermosets), ceramic materials, and/or suitable corrosion resistant metals.
• the support carrier is formed of polycarbonate.
• the abrasive member can be affixed to the support carrier using any suitable fastening technique including, for example, adhesives (e.g., conductive adhesives) and/or mechanical fasteners provided that sufficient cathodic protection circuitry is maintained.
• adhesives e.g., conductive adhesives
• mechanical fasteners provided that sufficient cathodic protection circuitry is maintained.
• anode The selection of material for the anode will be influenced by the materials used in the CMP process, and is within the ability of those skilled in the art.
• exemplary anodes include those anodes known for impressed current cathodic protection (ICCP).
• ICCP impressed current cathodic protection
• the anode may have any shape that does not interfere unduly with the abrading function of the abrading member.
• at least a portion of the anode is mounted on the support carrier at about the same height as the abrasive surface, such that the slurry will be able to simultaneously contact the anode and metallic substrate during the CMP process.
• anode 130 may be mounted to beveled portion 126 (i.e., chamfer) of peripheral edge 124 as shown in FIG. 1.
• exemplary suitable anode materials include: mixed metal oxides; platinum; platinized titanium, tantalum, and/or niobium; gold; palladium; silver-palladium; and graphite.
• Graphite has a low potential for adverse contamination of the wafer during processing but is more prone to environmental deterioration, especially in low pH aqueous environments.
• the anode must be insulated from the metallic substrate or a short circuit will result. Accordingly, it may be necessary to place the anode on an insulating pad or otherwise insulate it from the support carrier if the support carrier is conductive. If the support carrier is a dielectric material (e.g., an insulator), this is typically not a concern.
• the anode may be affixed to the support carrier by any suitable means including, for example, adhesives and/or mechanical fasteners.
• cathodic protection is that by connecting an external anode to the material to be protected from corrosion, and passing of an electrical DC current of sufficient strength and voltage, all areas of the material become cathodic and do not corrode. As practiced in the present disclosure, this is achieved by a cathodic protection circuit.
• the cathodic protection circuit electrically couples the anode to the positive terminal of an electric cell while electrically coupling the metallic substrate of the abrasive member to the negative terminal of the electric cell.
• the circuit When not in use, the circuit is open.
• electrolyte in the slurry used in the CMP process closes the circuit by bridging the metallic substrate and the anode.
• an exemplary cathodic protection circuit 140 includes electric cell 150, anode 130, and metallic substrate 112.
• Electric cell 150 which is disposed within cavity 128, includes negative terminal 152 and positive terminal 154 that are electrically coupled to anode 130 through insulated wires 158 disposed in channel 129 adjacent cavity 128.
• a corrosion resistant electrically insulating material 160 such as, for example, a
• thermosetting silicone resin available as 3M ESPE VINYL POLYSILOXANE
• cavity 128 may vary depending on the type and number of electric cells used.
• exemplary pad conditioner 200 has abrasive member 110, anode 130, and cavity 228, adapted to contain two coin cells (not shown) and adjacent channel 229.
• another exemplary pad conditioner 300 has abrasive member 110, anode 130, and cavity 328, adapted to contain three coin cells (not shown) and adjacent channel 329.
• electric cell 150 is a coin cell, although other cell designs are also useful.
• the selection of voltage for the electric cell is typically influenced by the composition of the metallic substrate and design parameters of the pad conditioner; for example, as discussed hereinbefore.
• the voltage of the electric cell should be sufficient to reduce oxidized metal species resulting from the metallic matrix.
• an electric cell with a voltage of at least 3 volts, 6 volts, or more is sufficient for many implementations of the cathodically protected pad conditioners, although lesser voltages may be useful in certain implementations.
• the electric cell is typically selected to have sufficient current capacity to last for the useful life of the cathodically protected pad conditioner, although this is not a requirement.
• a 4.25-inch (10.8-cm) diameter cathodically-protected pad conditioner was prepared generally as shown in FIGS. 1 and 2.
• the support carrier was made of polycarbonate.
• the anode was made of Ag-Pd alloy. 3M ESPE VINYL
• the abrasive member was substantially the same as the abrasive member used in a 3M A188 DIAMOND PAD CONDITIONER marketed by 3M Company.
• the 3M A188 DIAMOND PAD CONDITIONER has the abrasive member, which can be removed and cleaned, attached by means of a pressure-sensitive adhesive to a polycarbonate carrier.
• the metal matrix of the abrasive member is composed primarily of nickel, includes chromium as a minor alloying element, and may contain other minor components and impurities such as P, Si, Fe, C, and Mn.
• a pad conditioner was prepared as in Example 1, but without the electric cell.
• the comparative pad conditioner and the pad conditioner of Example 1 were separately contacted with a CMP polishing slurry available as SEMI-SPERSE W2000 - POLISHING SLURRY FOR ADVANCED TUNGSTEN CMP from Cabot

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Grinding-Machine Dressing And Accessory Apparatuses (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Polishing Bodies And Polishing Tools (AREA)
• Electroplating Methods And Accessories (AREA)
• Prevention Of Electric Corrosion (AREA)

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• 2010
  • 2010-07-15 US US12/837,055 patent/US8496511B2/en active Active
• 2011
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  • 2011-06-24 CN CN201180035149.8A patent/CN103003026B/zh active Active
  • 2011-06-24 JP JP2013519695A patent/JP5972264B2/ja not_active Expired - Fee Related
  • 2011-06-24 KR KR1020137003514A patent/KR20130128370A/ko not_active Ceased
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