WO2002100593A2 - Polishing pads with polymer filled fibrous web, and methods for fabricating and using same - Google Patents
Polishing pads with polymer filled fibrous web, and methods for fabricating and using same Download PDFInfo
- Publication number
- WO2002100593A2 WO2002100593A2 PCT/US2001/043208 US0143208W WO02100593A2 WO 2002100593 A2 WO2002100593 A2 WO 2002100593A2 US 0143208 W US0143208 W US 0143208W WO 02100593 A2 WO02100593 A2 WO 02100593A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- fibers
- polishing
- pad
- polymer
- polishing pad
- Prior art date
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
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
- B24D11/008—Finishing manufactured abrasive sheets, e.g. cutting, deforming
-
- 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.
- the polishing pads of the present invention are especially useful in chemical-mechanical planarization of semiconductor wafers.
- the invention relates to pads of increased stiffness to prevent over polishing, and increased hardness and thickness for greater useful life.
- the present invention is also applicable to the polishing of other surfaces, for example optical glass and CRT and flat panel display screens.
- the present invention further relates to methods for fabricating and using the pads.
- VLSI very large scale integration
- ULSI ultra large scale integration
- the greater device densities require greater degrees of planarity to permit the higher resolution lithographic processes required to form the greater number of devices having smaller features as incorporated in current designs.
- copper because of its low resistance, is increasingly being used as interconnects.
- etching techniques are used to planarize conductive (metal) and insulator surfaces.
- certain metals desirable for their advantageous properties when used as interconnects (Au, Ag, Cu) are not readily amenable to etching, thus the need for chemical-mechanical polishing (CMP).
- the various metal interconnects are formed through lithographic or damascene processes.
- the damascene technique is described in U.S. Patent Number 4,789,648, to Chow, et al. assigned to the assignee of the present invention, the entire contents of which are incorporated herein by reference.
- a first blanket metal layer is deposited on a first insulating layer, following which electrical lines are formed by subtractive etching through a first mask.
- a second insulating layer is placed over the first metallized layer, and holes are patterned into the second insulating layer using a second mask. Metal columns or plugs are formed by filling the holes with metal.
- a second blanket metal layer is formed over the second insulating layer, the plugs electrically connecting the first and second metal layers.
- the second metal layer is masked and etched to form a second set of electrical lines. This • process is repeated as required to generate the desired device.
- VLSI uses aluminum for the wiring and tungsten for the plugs because of their susceptibility to etching.
- the resistivity of copper is superior to either aluminum or tungsten, making its use desirable, but copper does not have desirable properties with respect to etching.
- Variations in the heights of the upper surface of the intermetal dielectric layer have several undesirable characteristics.
- the optical resolution of subsequent photolithographic processing steps may be degraded by non-planar dielectric surfaces. Loss of optical resolution lowers the resolution at which lines may be printed.
- the coverage of a second metal layer over the dielectric layer may be incomplete, leading to open circuits.
- CMP chemical-mechanical polishing
- a chemical-mechanical polishing method is described in U.S. Patent 4,944,836, Beyer, et al., assigned to the assignee of the present invention, the entire contents of which are incorporated herein by reference.
- Conventional polishing pads are made of a relatively soft and flexible material, such as nonwoven fibers interconnected together by a relatively small amount of a polyurethane adhesive binder, or may be laminated layers with variations of physical properties throughout the thickness of the pad.
- Multilayer pads generally have a flexible top polishing layer backed by a layer of stiffer material.
- the CMP art combines the chemical conversion of a surface layer to be removed, with the mechanical removal of the conversion product. Ideally, the conversion product is soft, facilitating high polishing rates.
- CMP pads must resolve two constraints relevant to the present invention.
- the surface in contact with the substrate to be polished must be resilient. Of particular relevance to the present invention is the problem of local over polishing, also known as "dishing", resulting from too flexible a pad. This is one of the key problems encountered during CMP of metal substrates.
- an increased number and density of defects in the polished surface may be caused by frayed and loose fibers that develop as conventional fibrous pads become worn. Such defects correlate with low yields of product.
- Some of the most commonly used polishing pads for manufacturing semiconductor chips are a very soft foam pad, or a soft nonwoven fiber pad.
- An advantage of a soft polishing pad is low defect density on the polished wafer and good within-wafer uniformity.
- soft CMP pads suffer from very short pad life requiring replacement after polishing about 50 wafers, and excessive dishing of the polished wafer because of the pad softness.
- a soft pad usually causes much more dishing compared with a hard pad.
- a hard polishing pad usually has better planarization capability than a soft pad.
- the defects count is much higher than with the soft pad and the within-wafer uniformity is usually much worse.
- hard pads may be conditionable, which means that the pad surface condition can be regenerated using a diamond disk or an abrasive roller to recondition the pad surface by removing worn areas and embedded debris. This reconditioning capability means that a hard pad may last much longer than a soft pad. Such reconditioning in situ also means that polishing tool down time for pad replacement is greatly reduced.
- the present invention addresses problems in the prior art and provides a relatively thick, stiff and hard pad comprising nonwoven fibers embedded in a polymer matrix.
- a nonwoven fiber mat is filled substantially completely with reactants for producing the polymer matrix before those reactants are fully cured. During curing, there may be some shrinkage producing voids in the matrix as the reactants are converted to the final hard polymer.
- the resulting fiber and polymer composite is sufficiently hard to be compatible with current and future CMP process chemistry, and is conditionable after use by grinding (dressing) with a diamond containing abrasive disk or roller to regenerate the working surface of the pad.
- the pad thickness may also be greater than previously used, which together with pad reconditionability, means that the pad life is significantly longer, such as polishing 500 to 1,000 wafers before pad replacement becomes necessary.
- Applications are envisioned in the semiconductor and optical industries.
- the present invention also relates to a method of making the above disclosed pads.
- the method comprises pressing the reactants into the interstices of a fibrous mat in a mold and then, when the interstices are substantially full, curing the reactants to produce the above disclosed polishing pad. Both heat and pressure are applied to cure the precursor system within the fibrous mat in the mold.
- the pad After curing and removal from the mold, the pad may be buffed with an abrasive disk or roller to remove a skin-like covering and to fracture a surface portion of the polymer to form a thin polishing surface layer of free fibers, segments of which remain embedded in the adjacent composite body.
- Typical materials suitable as a first fiber group are Rayon, polycarbonate, polyamide, polyphenylene sulfide, polyimide, Aramide fibers including Nomex and Kevlar, polyvinylchloride, Hemp, and combinations of these fibers.
- Typical materials suitable as a second fiber group are polyester, polypropylene, Nylon, acrylic, and polyethylene, and combinations of these fibers. The listed fibers are meant to be illustrative of the types that may be used, but the invention is not thereby limited to the enumerated types.
- the fibers of the first group are preferred because they provide pads having a higher hardness than the fibers of the second group. Combinations of the fibers of the first and second groups are also possible.
- the fibers and matrix polymers together typically have a hardness of about 30 Shore D to about 100 Shore D, and preferably about
- the fibers are preferably in the form of a web or mat, but may be individual fibers which are mixed with polymer precursors or to which polymer precursors are added.
- the fiber web may be a loose pile of fibers or may be formed by any well known nonwoven or woven production techniques, such as needle-punching, hydroentangling, chemical bonding, air-through bonding, weaving, knitting, felting or the like.
- the fiber mat alone preferably has a Durometer hardness from about 10 to about 90 Shore A, preferably from about 30 to about 70 Shore A, as measured by the aforesaid test method.
- the web of fibers, before impregnation with the polymer reactants (precursors), preferably has a thickness in the range of about 5 to about 130 mils, more preferably about 15 to about 100 mils, and most preferably about 50 to about 100 mils. During the molding process, these thicknesses may be reduced by about 10 to about 20%.
- the thickness of a new molded pad is preferably in the range from about 10 mils to about 100 mils. The pad is sufficiently strong and cohesive to be used and reconditioned down to a thickness of about 5 mils.
- the pads of the present invention typically comprise about 30 to about 70 percent by weight and preferably about 40 to about 60 percent by weight of the fibers and correspondingly typically about 70 to about 30 percent by weight and preferably about 60 to about 40 percent by weight of the polymeric matrix. The percentages of the fibers and polymeric matrix are based upon the total of the fibers and polymeric matrix in the pad.
- the pads of the present invention preferably have densities of about 0.5 g/cc to about 1.1 g/cc, and the fiber mats from which the pads are made preferably have densities of about 0.15 g/cc to about 0.9 g/cc.
- the fiber mat comprises a relatively loose network of fibers and this network is substantially completely filled with the precursor reactants for forming the polymer matrix in which the fiber mat becomes embedded after the reactants are cured.
- the cured polymer preferably forms a relatively hard but friable matrix.
- a small thickness or depth of surface polymer is removed to leave a thin surface layer of free fibers, segments of at least a portion of which remain embedded in the adjacent composite body of polymer and fibers, as can be seen in Figs. 1, 2, and 3.
- this fibrous polishing surface helps to reduce up to or more than about 90% of the defects count caused by using a conventional hard pad.
- the solid matrix formed by the polymer densely filling the fiber mat makes the pad up to 50% harder than the hardest conventional CMP pad presently on the market.
- the pads may have multiple layers, as described in U.S. Patent Application Serial No. 09/599,514, to allow for independent optimization of pad stiffness and hardness in independent layers.
- a bottom support layer imparts mechanical stiffness to the pad.
- the stiffness of the bottom support layer is preferably optimized in relation to the malleability of the material comprising the surface to be worked.
- the top working layer is preferably optimized with respect both to the properties of the surface to be polished, and with respect to the chemical properties of the abrasive mixture used in the CMP process.
- the support layer(s) has stiffer fibers and is thicker than the layer carrying the free fibers used as the polishing surface, and is typically about 55% to about 90% of the total thickness of the pad.
- stacked nonwoven and other types of fibrous pads have been tried in the past in an attempt to obtain better CMP performance.
- thin (5 to 15 mil thick) fibrous pads are not sufficiently durable and do not survive the CMP process.
- a single body polishing pad or the working body of a multi-layer pad can be buffed down to 5 mils while still maintaining structural integrity during the
- the free fiber layer provides a scratch-free polishing surface and the hard underlying body reduces the excessive dishing which usually occurs during CMP with softer pads.
- the invention allows for independent control of the optimal properties to prevent over polishing, for compatibility with the substrate to be polished, and for compatibility with the polishing compound.
- the fibers may be precoated with the same or a different polymer prior to being embedded in the matrix polymer.
- polymers suitable for precoating the fibers are copolymers of styrene and an acrylate or methacrylate such as ethyl or methyl acrylate or methacrylate; acrylonitrile rubbers; and butadiene-styrene rubbers, polyurethanes, fluorocarbons, and epoxy resins.
- the precoating may help maintain the stability of the free fibers by enhancing adhesion of segments of these fibers to the polymer matrix and can be used in amounts of about 10 to about 90% by weight and preferably about 15 to 50% by weight based upon the total weight of the fibers and precoating.
- the pads of the present invention can be fabricated by forming a loose fibrous web or mat of one or more layers of nonwoven fibers, followed by applying a precoating, when used, to the loose fibrous mat such as by spraying, and then curing the precoat.
- each of the fiber layers can separately be precoated and then stacked upon each other, followed by partially curing the precoat such as to the B-stage.
- the fibrous mat structure is then embedded into the matrix. This can be accomplished by placing the mat into a pad-shaped mold and applying an unreacted viscous polymer precursor system on top of the mat, such as an isocyanate system known as ADIPRENE from Uniroyal or AIRFLEX from Air Products.
- the mold is then closed and sufficient differential pressure is applied for causing the polymer precursors to substantially completely fill in the spaces (interstices) between the fibers and thereby embed them in an essentially continuous polymer matrix.
- a vacuum such as about minus 10 psig, may be used to pull the polymeric reactants (precursors) into the fibrous mat.
- the mold is heated to affect either a partial or a final cure of the matrix polymer.
- the curing of the matrix polymer is typically performed at temperatures of about 60° to about 250°F, preferably about 100°F to about 180°F; a pressure of about 1 psig to about 200 psig preferably about 10 psig to about 150 psig, more preferably about 50 psig to about 75 psig; for about 5 to about 24 hours.
- a final cure may be affected at ambient pressure in an oven or the like, the time and temperature of this cure depending on the polymer and extent of the partial cure.
- the present invention substantially completely fills the interstices of the fiber mat with the reactants for the polymer, such as an isocyanate system for polyurethane, to provide an extremely hard polymer matrix with embedded fibers.
- the pads of the invention also may be made of one or more such hard layers of fiber and polymer composite.
- the fibers of the mat used have fiber diameters preferably in the range of about 15 microns to about 70 microns, more preferably about 20 microns to about 50 microns, and most preferably about 25 microns. Because of the unusually hard matrix of the pad, it may be relatively inflexible.
- the pad may be provided with holes to increase its flexibility.
- holes are used to increase pad flexibility, they preferably pass all the way through the pad from the working side to the mounting side, and the size of the holes are preferably in the range of 1/16 inch to 1/4 inch in diameter, with the 1/4 inch holes being preferably spaced 1/2 inch apart and the 1/16 holes being preferably spaced about 1/4 inch apart.
- the pads of the present invention are especially amenable to grooving to provide a grooved polishing pad that is capable of consistently forming uniformly polished surfaces on high quality wafers.
- the apparatus for grooving a pad may comprise a platen with positioning post for holding the pad in position for engagement by a router to machine grooves in the working surface of the pad.
- a spacing mechanism may be used to provide a constant and precise separation between the working surface of the pad and the chuck for holding and rotating the router.
- the present pad design therefore offers a versatility of properties and performance required to give a high degree of planarization and global uniformity to a variety of polished substrates.
- the pads of the present invention can be used for polishing aluminum and aluminum alloys such as Al-Si and Al-Cu, Cu, Cu alloys, W, W alloys, a variety of adhesion and diffusion barriers such as Ti, Ti alloys, TiN, Ta, Ta alloys, TaN, Cr and the like, silicon oxide, polysilicon, silicon nitride, Au, Au alloys, as well as other metals and alloys, and glasses of various compositions.
- the polishing slurries employed can be any of the known CMP slurries.
- Particular examples are alumina in deionized water, or an acidic composition having a pH less than 3 obtained by the addition of hydrofluoric or nitric acid to the alumina and water slurry; and slurries with pH 3 or greater, including basic slurries having a pH above 7.
- An embodiment, suitable for the semiconductor industry is a substantially cylindrical pad having general dimensions such that it might be used in a polishing apparatus, for example in the equipment described in the IBM Technical Disclosure Bulletin. Vol. 15, No. 6, November 1972, pages 1760-1761, the entire contents of which are incorporated herein by reference.
- the polishing apparatus includes a polishing station having a rotatable platen on which is mounted a polishing pad, such as illustrated diagrammatically in Fig. 14 of Provisional Application Serial no. 60/214,774, referred to above.
- the pad in this embodiment is preferably about 10 to about 36 inches, more preferably about 24 inches in diameter, the latter being capable of polishing "eight-inch” or "twelve-inch” semiconductor wafers.
- the platen typically rotates the pad at speeds from 30 to 200 revolutions per minute, though speeds less than and greater than this range may be used.
- Semiconductor wafers are typically mounted on a rotatable carrier head using a vacuum chuck.
- the head presses the wafer against the pad causing polishing, for example with 1 to 10, preferably 2 to 8 pounds per square inch pressure, but greater or lesser pressures could also be used.
- polishing for example with 1 to 10, preferably 2 to 8 pounds per square inch pressure, but greater or lesser pressures could also be used.
- the rate of polishing is controlled by the composition of the slurry, the rotation rates of the head and platen, and the contact pressure.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Polishing Bodies And Polishing Tools (AREA)
- Nonwoven Fabrics (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003503398A JP2004528997A (en) | 2000-11-20 | 2001-11-20 | Abrasive pad having a polymer-filled fibrous web and methods of making and using the same |
CA002441419A CA2441419A1 (en) | 2000-11-20 | 2001-11-20 | Polishing pads with polymer filled fibrous web, and methods for fabricating and using same |
EP01274075A EP1341643A4 (en) | 2000-11-20 | 2001-11-20 | Polishing pads with polymer filled fibrous web, and methods for fabricating and using same |
AU2001297847A AU2001297847A1 (en) | 2000-11-20 | 2001-11-20 | Polishing pads with polymer filled fibrous web, and methods for fabricating and using same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/715,184 US6712681B1 (en) | 2000-06-23 | 2000-11-20 | Polishing pads with polymer filled fibrous web, and methods for fabricating and using same |
US09/715,184 | 2000-11-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002100593A2 true WO2002100593A2 (en) | 2002-12-19 |
WO2002100593A3 WO2002100593A3 (en) | 2003-06-05 |
Family
ID=24872997
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/043208 WO2002100593A2 (en) | 2000-11-20 | 2001-11-20 | Polishing pads with polymer filled fibrous web, and methods for fabricating and using same |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1341643A4 (en) |
JP (1) | JP2004528997A (en) |
AU (1) | AU2001297847A1 (en) |
CA (1) | CA2441419A1 (en) |
WO (1) | WO2002100593A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101129905B1 (en) * | 2004-05-11 | 2012-03-23 | 이노패드, 인코포레이티드 | Polishing pad |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TWI409136B (en) | 2006-07-19 | 2013-09-21 | Innopad Inc | Chemical mechanical planarization pad having micro-grooves on the pad surface |
JP5234916B2 (en) * | 2007-01-30 | 2013-07-10 | 東レ株式会社 | Laminated polishing pad |
US8377351B2 (en) * | 2008-04-01 | 2013-02-19 | Innopad, Inc. | Polishing pad with controlled void formation |
KR101050274B1 (en) | 2009-12-31 | 2011-07-19 | 한국생산기술연구원 | Abrasive pad containing polishing pad and method for manufacturing same |
JP2012101298A (en) * | 2010-11-08 | 2012-05-31 | Ritsumeikan | Polishing pad |
JP2015127094A (en) * | 2015-03-04 | 2015-07-09 | 学校法人立命館 | Polishing pad |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4927432A (en) * | 1986-03-25 | 1990-05-22 | Rodel, Inc. | Pad material for grinding, lapping and polishing |
US5197999A (en) * | 1991-09-30 | 1993-03-30 | National Semiconductor Corporation | Polishing pad for planarization |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4728552A (en) * | 1984-07-06 | 1988-03-01 | Rodel, Inc. | Substrate containing fibers of predetermined orientation and process of making the same |
-
2001
- 2001-11-20 AU AU2001297847A patent/AU2001297847A1/en not_active Abandoned
- 2001-11-20 JP JP2003503398A patent/JP2004528997A/en active Pending
- 2001-11-20 CA CA002441419A patent/CA2441419A1/en not_active Abandoned
- 2001-11-20 EP EP01274075A patent/EP1341643A4/en not_active Withdrawn
- 2001-11-20 WO PCT/US2001/043208 patent/WO2002100593A2/en not_active Application Discontinuation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4927432A (en) * | 1986-03-25 | 1990-05-22 | Rodel, Inc. | Pad material for grinding, lapping and polishing |
US5197999A (en) * | 1991-09-30 | 1993-03-30 | National Semiconductor Corporation | Polishing pad for planarization |
Non-Patent Citations (1)
Title |
---|
See also references of EP1341643A2 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101129905B1 (en) * | 2004-05-11 | 2012-03-23 | 이노패드, 인코포레이티드 | Polishing pad |
Also Published As
Publication number | Publication date |
---|---|
AU2001297847A1 (en) | 2002-12-23 |
CA2441419A1 (en) | 2002-12-19 |
WO2002100593A3 (en) | 2003-06-05 |
EP1341643A4 (en) | 2004-06-09 |
EP1341643A2 (en) | 2003-09-10 |
JP2004528997A (en) | 2004-09-24 |
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