WO1998045112A1 - Polishing pads and methods relating thereto - Google Patents

Polishing pads and methods relating thereto Download PDF

Info

Publication number
WO1998045112A1
WO1998045112A1 PCT/US1998/006757 US9806757W WO9845112A1 WO 1998045112 A1 WO1998045112 A1 WO 1998045112A1 US 9806757 W US9806757 W US 9806757W WO 9845112 A1 WO9845112 A1 WO 9845112A1
Authority
WO
WIPO (PCT)
Prior art keywords
fibers
polishing pad
pad
polishing
polymer solution
Prior art date
Application number
PCT/US1998/006757
Other languages
French (fr)
Inventor
Heinz F. Reinhardt
Elmer William Jensen
Original Assignee
Rodel Holdings, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rodel Holdings, Inc. filed Critical Rodel Holdings, Inc.
Publication of WO1998045112A1 publication Critical patent/WO1998045112A1/en

Links

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
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B24B37/20—Lapping pads for working plane surfaces
    • B24B37/24—Lapping pads for working plane surfaces characterised by the composition or properties of the pad materials
    • 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
    • B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
    • B24B13/01—Specific tools, e.g. bowl-like; Production, dressing or fastening of these tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
    • B24D11/001—Manufacture of flexible abrasive materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D13/00—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor
    • B24D13/14—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor acting by the front face
    • B24D13/145—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor acting by the front face having a brush-like working surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
    • B24D3/28—Resins or natural or synthetic macromolecular compounds

Definitions

  • the present invention relates to polishing pads used for creating a smooth, ultra-flat surface on such items as glass, semiconductors, dielectric/metal composites and integrated circuits.
  • Polishing generally consists of the controlled wear of an initially rough surface to produce a smooth specular finished surface. This is commonly accomplished by rubbing a pad against the surface of the article to be polished (the workpiece) in a repetitive, regular motion while a solution containing a suspension of fine particles (the slurry) is present at the interface between the polishing pad and the workpiece.
  • Polishing pads are normally produced by impregnation of felt with polymer solutions using water miscible solvents such as DMF followed by coagulation with water or water solvent blends, then drying and buffing or splitting/buffing.
  • the polymer solution is coated onto a substrate followed by coagulating.
  • This process leads to the formation of vertically oriented pores (VO pores) which serve as slurry reservoir during polishing.
  • VO pores vertically oriented pores
  • the impregnation/coagulating method gives material with mostly horizontally oriented fibers and the coating method results in a coating without any fiber reinforcement except the fibers present in the substrate.
  • the only way to make polishing material with vertically oriented fibers is by laminating horizontally oriented product to make a vertically oriented product such as described in USPatent No. 4,728,552.
  • a patent which shows one method of forming a polishing sheet material with pores on the surface to provide slurry reservoir is USPatent No. 4,753,838.
  • the pad surface is made of cellular polyurethane.
  • a polishing pad is provided which is comprised of vertically oriented fibers.
  • Such pads can be produced by electrostatically flocking fibers onto a substrate.
  • the fibers are hollow.
  • the pad comprised of vertically oriented fibers may be coated with a polymer solution to fill the voids between the fibers.
  • the surface of pads coated with a polymer solution may be sanded to remove polymer skin and open the hollow fiber ends.
  • a method for polishing a workpiece wherein polishing pads as described above are used to planarize a workpiece by contacting the surface of the polishing pad and a surface of the workpiece while there is motion between the polishing pad and the workpiece.
  • a process has been developed to make polishing pads containing vertically oriented fibers by electrostatically flocking fibers vertically onto substrates.
  • the material may then be coated with polymer solution to fill the voids between the fibers. No polymer coating/impregnation may be needed if the fibers are flocked very densely.
  • a process variation which uses hollow or multichannel fibers such as hollow polyester or nylon fibers. This results in surface structures with increased slurry reservoir. Hollow polyester and nylon fibers are commercially available as well as higher denier triocular and tetraocular nylon (Tynex, a trademark of the DuPont Company).
  • Hollow fiber felts made by electrostatic flocking and used for the impregnation/coagulating process give polishing surfaces with vertically oriented hollow fibers which act as slurry reservoir by themselves or in combination with the pores generated during coagulation. This process results in a new type of polishing pad which not only has vertically oriented fiber reinforcement but also has increased slurry uptake because of the hollow nature of the fiber used.
  • a variety of samples were prepared by flocking solid and one- or multichannel fibers electrostatically onto substrates with most of the fibers vertically oriented. Microscope examination of flocked fiber samples show nearly 100% vertical fiber orientation.
  • the fiber flock used was usually between 0.4 to 0.8 mm in length.
  • Hollow fibers used in the experiments included hollow polyester and 3- and 4- channel nylon. Some samples were coated with polyurethane solutions to fill the voids between the fibers. The coagulated material was sanded to remove the skin and to open the hollow fiber ends and pores in the polymer.
  • Fibers flocked onto a polymer film or onto a foamed backing provided surfaces which would make excellent pads for chemical mechanical planarization.
  • the surface was very uniform and choice of backing material makes it possible to obtain the desired stiffness or resilience for a given polishing operation.
  • Electrostatic flocking of short, high denier fibers is a well known art.
  • Any type of adhesive may be used to adhere the vertically oriented fibers to a substrate.
  • the adhesive may be a hot melt, aqueous based, or solvent based.
  • the adhesive needs to be resistant to water and alkaline conditions up to a pH of 12. Since polyurethanes are commonly used in the manufacture of pads for chemical mechanical polishing, they are a preferred material for the flocking process adhesive.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Abstract

A polishing pad is provided which is comprised of vertically oriented fibers. Such pads can be produced by electrostatically flocking fibers onto a substrate. Preferably the fibers are hollow.

Description

POLISHING PADS AND METHODS RELATING THERETO
This application claims the benefit of U. S. Provisional Application No. 60/043405 filed on April 4, 1997.
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to polishing pads used for creating a smooth, ultra-flat surface on such items as glass, semiconductors, dielectric/metal composites and integrated circuits.
Description of Related Art Polishing generally consists of the controlled wear of an initially rough surface to produce a smooth specular finished surface. This is commonly accomplished by rubbing a pad against the surface of the article to be polished (the workpiece) in a repetitive, regular motion while a solution containing a suspension of fine particles (the slurry) is present at the interface between the polishing pad and the workpiece.
Polishing pads are normally produced by impregnation of felt with polymer solutions using water miscible solvents such as DMF followed by coagulation with water or water solvent blends, then drying and buffing or splitting/buffing. In another process the polymer solution is coated onto a substrate followed by coagulating. This process leads to the formation of vertically oriented pores (VO pores) which serve as slurry reservoir during polishing. The impregnation/coagulating method gives material with mostly horizontally oriented fibers and the coating method results in a coating without any fiber reinforcement except the fibers present in the substrate. The only way to make polishing material with vertically oriented fibers is by laminating horizontally oriented product to make a vertically oriented product such as described in USPatent No. 4,728,552.
A patent which shows one method of forming a polishing sheet material with pores on the surface to provide slurry reservoir is USPatent No. 4,753,838. The pad surface is made of cellular polyurethane.
SUMMARY OF THE INVENTION
A polishing pad is provided which is comprised of vertically oriented fibers. Such pads can be produced by electrostatically flocking fibers onto a substrate. Preferably the fibers are hollow. Optionally, the pad comprised of vertically oriented fibers may be coated with a polymer solution to fill the voids between the fibers. The surface of pads coated with a polymer solution may be sanded to remove polymer skin and open the hollow fiber ends.
A method for polishing a workpiece is provided wherein polishing pads as described above are used to planarize a workpiece by contacting the surface of the polishing pad and a surface of the workpiece while there is motion between the polishing pad and the workpiece.
DETAILED DESCRIPTION OF THE INVENTION A process has been developed to make polishing pads containing vertically oriented fibers by electrostatically flocking fibers vertically onto substrates. The material may then be coated with polymer solution to fill the voids between the fibers. No polymer coating/impregnation may be needed if the fibers are flocked very densely. Of particular interest is a process variation which uses hollow or multichannel fibers such as hollow polyester or nylon fibers. This results in surface structures with increased slurry reservoir. Hollow polyester and nylon fibers are commercially available as well as higher denier triocular and tetraocular nylon (Tynex, a trademark of the DuPont Company). Hollow fiber felts made by electrostatic flocking and used for the impregnation/coagulating process give polishing surfaces with vertically oriented hollow fibers which act as slurry reservoir by themselves or in combination with the pores generated during coagulation. This process results in a new type of polishing pad which not only has vertically oriented fiber reinforcement but also has increased slurry uptake because of the hollow nature of the fiber used. A variety of samples were prepared by flocking solid and one- or multichannel fibers electrostatically onto substrates with most of the fibers vertically oriented. Microscope examination of flocked fiber samples show nearly 100% vertical fiber orientation. The fiber flock used was usually between 0.4 to 0.8 mm in length. Hollow fibers used in the experiments included hollow polyester and 3- and 4- channel nylon. Some samples were coated with polyurethane solutions to fill the voids between the fibers. The coagulated material was sanded to remove the skin and to open the hollow fiber ends and pores in the polymer.
Fibers flocked onto a polymer film or onto a foamed backing (such as foamed rubber) provided surfaces which would make excellent pads for chemical mechanical planarization. The surface was very uniform and choice of backing material makes it possible to obtain the desired stiffness or resilience for a given polishing operation.
Electrostatic flocking of short, high denier fibers is a well known art. Any type of adhesive may be used to adhere the vertically oriented fibers to a substrate. The adhesive may be a hot melt, aqueous based, or solvent based. For the purpose of making the surface layer of a pad useful for chemical mechanical polishing of a workpiece, such as a semiconductor wafer, the adhesive needs to be resistant to water and alkaline conditions up to a pH of 12. Since polyurethanes are commonly used in the manufacture of pads for chemical mechanical polishing, they are a preferred material for the flocking process adhesive.
The scope of the invention is limited only by the claims which follow.

Claims

1. A polishing pad comprised of vertically oriented fibers said pad being produced by electrostatically flocking fibers onto a substrate.
2. A polishing pad according to claim 1 wherein said fibers are hollow.
3. A polishing pad according to claim 1 wherein said pad comprised of said fibers electrostatically flocked onto said substrate is coated with a polymer solution to fill the voids between said fibers.
4. A polishing pad according to claim 2 wherein said pad comprised of said fibers electrostatically flocked onto said substrate is coated with a polymer solution to fill the voids between said fibers. 5. A polishing pad according to claim 4 wherein the surface of said coated pad is sanded to remove polymer skin and open the hollow fiber ends. 6. A polishing pad according to claim 4 wherein said polymer solution is a urethane polymer solution. 7. A polishing pad according to claim 2 wherein said fibers are polyester or nylon. 8. A polishing pad according to claim 1 wherein said fibers are between about 0.4 and 0.8 mm in length.
. A polishing pad according to claim 2 wherein said fibers are between about 0.4 and 0.8 mm in length.
10. A method for polishing a workpiece comprising: (a) providing a polishing pad comprised of vertically oriented fibers said pad being produced by electrostatically flocking fibers onto a substrate, (b) planarizing said workpiece by contacting the surface of said polishing pad and said workpiece while there is motion between said polishing pad and said workpiece.
11. A method according to claim 10 wherein said fibers are hollow. 12. A method according to claim 10 wherein said pad comprised of said fibers electrostatically flocked onto said substrate is coated with a polymer solution to fill the voids between said fibers.
13. A method according to claim 11 wherein said pad comprised of said fibers electrostatically flocked onto said substrate is coated with a polymer solution to fill the voids between said fibers.
14. A method according to claim 13 wherein the surface of said coated pad is sanded to remove polymer skin and open the hollow fiber ends.
15. A method according to claim 13 wherein said polymer solution is a urethane polymer solution.
16. A method according to claim 11 wherein said fibers are polyester or nylon.
17. A method according to claim 10 wherein said fibers are between about 0.4 and 0.8 mm in length.
8. A method according to claim 10 wherein said fibers are between about 0.4 and 0.8 mm in length.
PCT/US1998/006757 1997-04-04 1998-04-03 Polishing pads and methods relating thereto WO1998045112A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US4340597P 1997-04-04 1997-04-04
US60/043,405 1997-04-04

Publications (1)

Publication Number Publication Date
WO1998045112A1 true WO1998045112A1 (en) 1998-10-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1998/006757 WO1998045112A1 (en) 1997-04-04 1998-04-03 Polishing pads and methods relating thereto

Country Status (1)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1057590A1 (en) * 1999-06-01 2000-12-06 Etablissements D Curt Société Anonyme Consumable polishing element, specially for finishing optical glasses
US6589106B1 (en) 1997-04-04 2003-07-08 Etablissements D Curt, Societe Anonyme Consumable polishing element, particularly for finishing optical glass
WO2004021855A1 (en) 2002-09-05 2004-03-18 3M Innovative Properties Company Flocked substrates for use as scouring materials

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3772132A (en) * 1972-04-03 1973-11-13 Malden Mills Inc Flocked fabric and method for making same
US5569521A (en) * 1995-04-21 1996-10-29 Francoeur, Sr.; Normand Flexible cleaning pad

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3772132A (en) * 1972-04-03 1973-11-13 Malden Mills Inc Flocked fabric and method for making same
US5569521A (en) * 1995-04-21 1996-10-29 Francoeur, Sr.; Normand Flexible cleaning pad

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6589106B1 (en) 1997-04-04 2003-07-08 Etablissements D Curt, Societe Anonyme Consumable polishing element, particularly for finishing optical glass
EP1057590A1 (en) * 1999-06-01 2000-12-06 Etablissements D Curt Société Anonyme Consumable polishing element, specially for finishing optical glasses
FR2794390A1 (en) * 1999-06-01 2000-12-08 D Curt Ets CONSUMABLE POLISHING ELEMENT, ESPECIALLY FOR THE FINISHING OF OPTICAL LENSES
WO2004021855A1 (en) 2002-09-05 2004-03-18 3M Innovative Properties Company Flocked substrates for use as scouring materials

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