WO2012138705A2

WO2012138705A2 - A self-conditioning polishing pad and a method of making the same

Info

Publication number: WO2012138705A2
Application number: PCT/US2012/032089
Authority: WO
Inventors: Scott DASKIEWICH
Original assignee: Universal Photonics, Inc.
Priority date: 2011-04-05
Filing date: 2012-04-04
Publication date: 2012-10-11
Also published as: WO2012138705A3

Abstract

The present invention is directed to a self-conditioning polishing pad. The self-conditioning polishing pad comprises a water-insoluble polymeric foam matrix and water-insoluble polymeric foam particles within the foam matrix. The particles are coated with a water-soluble component over a portion of the surface area of the particle. The particles may have a diameter in the range of 5 to 2000 microns in diameter.

Description

A SELF-CONDITiONING POLISHING PAD AND

A METHOD OF MAKING THE SAME The present invention is generally related to a self-conditioning polishing pad, comprising a water-insoluble polymeric foam matrix containing water-insoluble polymeric foam particles coated with a water-soluble component,

Background Of The Iraventioa

in the common use of a polyurethane polishing pad, the pad sirrface which contacts the part to be polished is typically conditioned before and during polishing. One problem encountered during the use of polyurethane foam polishing pads is the continuous need to recondition the pad. Conditioning in most polishing applications involves moving a conditioning tool across the pad contact surface which creates a nap of sheared polyurethane, flattens out pad topography, and cleans out accumulated slurry and swarf from pores, A conditioning tool comprised of a metal puck thai is impregnated on one side with diamond powder or another similarly hard abrasive material. In the normal course of polishing, a polishing pad will experience a decline in performance (i.e., Stock removal, part flatness, part defects, and/or surface roughness) that is related to the flattening of the polyurethane nap, changes in the pad topography, and clogging of pores with slurry and swarf.

Polishing pads are useful in many applications. Two such applications are polishing glass and polishing wafers. Regardless of the application, a polishing pad is moved relative to the object (e.g., glass, Si wafer, Sapphire wafer, etc.) being polished. This relative movement may be created by a rotating the polishing pad, by rotating the object being polished, or a combination of such movements. Other linear or any useful relative motion may be used between the polishing pad and the object being polished. In some embodiments, a force may be applied to press the polishing pad in contact with the wafer.

The polishing may be performed to varying degrees such as to remove larger imperfections, to achieve a mirror finish and/or final flatness, etc.

Conventionally, the process of polishing silicon semiconductor substrate wafers to improve flatness is accomplished by a mechanochernieai process in which one or more polishing pads, typically made of urethane, is used with an alkaline polishing solution (slurry), commonly comprising fine abrasive particles such as silica or cerium. The silicon 9 wafer is supported between a platen covered with a polishing pad and a carrier to which the wafer is attached, or, in the case of double-sided polishing, the wafer is held between two platens, each covered with a polishing pad. The pads are typically about 1 mm thick and pressure is applied to the wafer surface. The wafer is mechanochemieaily polished by relative movement between the platen and the wafer.

During polishing, pressure is applied to the wafer surfaces by pressing the pad and the wafer together in a polishing tool, whereby a uniform pressure is generated over the entire surface owing to the compressive deformation of pads. Polishing tools often have dynamic heads which can be rotated at different rates and at varying axes of rotation. This removes material and evens out any irregular topography, making the wafer flat or planar.

Unfortunately, typical prior art polishing pads tend to need to be conditioned and therefore replaced frequently because conditioning removes a portion of the pad thickness. For example, such polishing pads may need to be replaced every 5-10 days. It is desirable to have a polishing pad that can maintain its optimal polishing performance longer before conditioning is necessary, thereby giving the polishing pad a longer polishing life, in this manner, more polishing can be performed and thus more product can be made in a set period of time. In this regard, it is desirable to have a polishing pad that is self conditioning.

Summary Of The Invention

The present invention is directed to a self-conditioning polishing pad. The self- conditioning polishing pad comprises a water-insoluble polymeric foam matrix and water- insoluble polymeric foam particles within the foam matrix. The particles are coated with a water-soluble component over a portion of the surface area of the particle. The particles may have a diameter in the range of 5 to 2000 microns in diameter.

Brief Description Of The Drawings

The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present invention, however, can be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements, and wherein:

Figure 1 illustrates a cross section of a self conditioning polishing pad in accordance with one exemplary embodiment of the present invention; Figure 2 illustrates a self conditioning polishing pad, the part to be polished, and a polishing tool, ail in accordance with one exemplary embodiment of the present invention; and

Figure 3 illustrates an exemplary method flow chart for manufacturing an exemplary self conditioning pad in accordance with one exemplaiy embodiment of the present invention,

Detailed Description

In accordance with an exemplary embodiment of the present invention, a polishing pad is disclosed for use in polishing glass, silicon semiconductor substrate wafers, and Sapphire wafers (among other things). In this exemplary embodiment, the polishing pad is chemically and/or physically configured to comprise particles formed in the pad in such a manner that the pad is a self-conditioning pad. Stated another way, the pad can be configured to self condition so as to effectively function for longer periods of time without interruption of operation tor conditioning relative to pads that are not so configured,

POLISHING PADS

hi accordance with an exemplary embodiment, a polishing pad may comprise a foam matrix and foam particles within the foam matrix, hi an exemplary embodiment, the polishing pad comprises a water-insoluble polymeric foam matrix and water-insoluble polymeric foam particles within the water-insoluble polymeric foam, matrix. The water- insoluble polymeric foam particles may be coated over a portion of the particles' surface area with a water-soluble component.

With reference now to Figure 1, and in accordance with an exemplary embodiment, a polishing pad 100 comprises a water-insoluble polymeric foam matrix ] 10 and water- insoluble polymeric foam particles 120 within water-insoluble polymeric foam matrix 1 10, The water-insoluble polymeric foam particles 120 may be coated over a portion of the particles' surface area with a water-soluble component 125. Water-insoluble polymeric foam particle 120 and water-soluble component coating 125 together form a coated particle 130.

Particles

In an exemplary embodiment, water-insoluble polymeric foam particles 120 are formed by first making a larger water-insoluble polymeric foam object and then creating smaller particles out of the larger foam object. The smaller particles can be formed out of the larger foam object through any suitable method. In one exemplary embodiment, the larger foam object is ground into smaller particles. For example, the water-insolubie foam particles may be formed by cryogemea!ly grinding the larger foam object. In other exemplar)' embodiments, particles may be formed in a hammer mill. Furthermore, any other suitable method for forming particles may be used.

in one exemplary embodiment, the water-insoluble polymeric foam particles have a diameter between about 5 and 500 microns. In another example embodiment, the water- insolubie polymeric foam particles have a diameter of between abou t 5 and 1000 microns, or of between about 5 and 2000 microns. In another example embodimen the water-insolubie polymeric foam particles have a diameter of between about 500 and 1500 microns. In another exemplary embodiment, the water-soluble component comprises at least one of: a water-soluble polymer, a surfactant, an etchant, a pH buffer, an acid, and a base. In another example embodiment, the water-soluble component comprises B-eyclodextrin. Moreover, in another exemplary embodiment, the water-insoluble polymeric foam particles have a bulk density of about 0.2 to 0.85 g/cm^A3 , in yet another example embodiment the water- insoluble polymeric foam particles have a bulk density of about 0.3 to 0.5 g/cm^A3.

Coating

In accordance with an exemplary embodiment, particles 120 are coated with a water- soluble coating. In one exemplary embodiment, particles 120 are coated through use of a spray coating. In another exemplary embodiment, particles 120 are formed by making slurry of water-insoluble particles contained in a water-soluble liquid phase then drying and finally cryogrinding or hammer milling the solidified water-insoluble particle/soluble composite into particles. In an exemplary embodimen particles 120 are dried and clarified after the spray coating, in this manner, a coated particle 130 comprises a particle 120 that is coated with a water-soluble coating 125. In another exemplary embodiment, the water- insoluble polymeric foam particles are coated over about 5% to 90% of the surface area of said water-insoluble polymeric foam particles. In yet another example embodiment, the water-insolubie polymeric foam particles are coated over about 20% to 70% of the surface area of said water-insoluble polymeric foam particles.

In an exemplary embodiment, the coated particles comprise about 10% to 90% by volume of the polishing pad. In yet another example embodiment, the coated particles comprise about 10% to 30% by volume of the polishing pad. in an exemplary embodiment, the water-soiuble coating is comprised of organic or inorganic water-soluble particles. Specific examples of the organic water-soluble particles include particles of saccharides (polysaccharides, e.g., a, (3 or y-eyclodexirin, dextrin and starch, lactose, mannite, and the like), celluloses (hydroxypropyl cellulose, methylcellulose, and the like), proteins, a polyvinyl alcohol, a polyvinyl pyrrolidone, a polyacryiic acid, a poiyacrylate, a polyethylene oxide, water-soluble photosensitive resins, a sulfonated poiyisoprene, and a sulfonated polyisoprene copolymer.

in an exemplary embodiment, coated particles 130 are added into the mix during the process of forming matrix 110 of polishing pad 100. Thus, in an exemplary embodiment, coated particles 130 will be set within matrix 1 10,

n one exemplary embodiment, coated particles 130 are mixed into the matrix using high-shear blending. Other mixing methods include double planetary, kneading swing arm, and inline mixing with direct filler feed. Furthermore, any method of mixing may be used that is configured to randomly space out coated particles 130 within matrix 1 10. Moreover, the mixing process may entrain air bubbles within the foam (whether it be within the foam particles when forming them, or whether it may be within matrix 1 10). Furthermore any suitable method for introducing pores within matrix 1 10 or particles 120 may be used. These methods may include ambient air frothing, water blown~C0₂ evolution, physical blowing agents such as HFC, decompositionai blowing agents such as azonitriies. microspheres, and injected inert gasses.

Method of making the pad.

In an exemplary embodiment, the water-insoluble foam object (that is to become the water-insoluble foam particles) is formed by mixing a polyurethane prepolymer, a curing agent, a surfactant, and a foaming agent. In some embodiments, an abrasive filler may also be mixed with the other ingredients. In some other embodiments, the water-insoluble foam object can be polyurethane foam, epoxy foam, polyethylene foam, poly butadiene foam, ionomer foam, or any other water-insoluble polymer foam. As mentioned above, the water- insoluble foam object may then be ground down into smaller water-insoluble foam particles 120, These particles 120 may then be coated to form water-insoluble coated form particles 130. The coated particles 330 may then be included in the formation of the overall pad.

In an exemplary embodiment, polishing pad 100 is then formed by mixing a prepolymer, a curing agent, a surfactant, a foaming agent, and coated particles 330. In some embodiments, an abrasive filler may aiso be mixed with the other ingredients. The water- insoluble foam matrix can be polyurethane foam, epoxy foam, polyethylene foam, polybutadiene foam, ionomer foam, or any other water-insoluble polymer foam. The components may be mixed together using high-shear blending to incorporate the coated particles into the matrix. A foam bun may be formed in an open mold. The foam bun may be cured and then sliced into sheets. Each sheet comprises one polishing pad 100. In an exemplary embodiment the pad comprises open cells. The open cell content of the water- insoluble polymeric foam particle may be about 5% to about 75%. In yet another example embodiment, the open cell content of the water-insolubie polymeric foam particle may be about 20% to about 60%. in another exemplary embodiment, the water-soluble component coating the water-insoluble foam particle may be between 50% and 100% soluble. In yet another example embodiment, the water soluble component coating the water-insoluble foam particle may be between 90% and 100% water-soluble. Moreover, in another exemplary embodiment the water-insoluble polymeric foam matrix has a bulk, density of 0.2 to 0.85 g/cm^A3, In yet another example embodiment, the water-insoluble polymeric foam matrix has a bulk density of 0.3 to 0.7 g/em^A3

Matrix 1 10 and particle 120, in an exemplary embodiment, are both made of a water- insoluble foam material. In one embodiment, the materials for matrix 1 10 and particle 120 are identical to each other, In this regard, scrap material that is a byproduct of the production process can be used to create additional particles. In another exemplary embodiment, the materials are different from each oilier. The matrix and particle materials may be selected from any of a number of possible materials.

For example, in an exemplary embodiment, the water-insoluble foam material for either of matrix 1 10 and/or particle 120 may be made from a polymer oam - such as polyurethane, polyethylene, polystyrene, polyvinyl chloride, aeryi foam or a mixture thereof. These polymer foams can be produced by mixing a polymerizing agent, typicall an isoeyanate-iermrnated monomer, and a prepolymer, typically an isocyanate functional polyol or a poiyol-diol mixture.

Classes of polymerizing agents, isocyanate-terrninated monomers, that may be used to prepare the particulate crosslinked polyurethane include, but are not limited to, aliphatic polyisocyanates; ethyienicaily unsaturated polyisocyanates; alicyclic polyisocyanates; aromatic polyisocyanates wherein the isocyanate groups are not bonded directly to the aromatic ring, e.g., xylene diisocyanate; aromati polyisocyanates wherein the isocyanate groups are bonded directly to the aromatic ring, e.g., benzene diisocyanate; halogenated, alkylated, alkoxvlated, nitrated, carbodlimide modified, urea modified and biuret modified derivatives of poivisocyanates belonging to these classes; and dimerized and trimerized products of poivisocyanates belonging to these ciasses.

Examples of aliphatic poivisocyanates from which the isocyanate functional reactant may be selected include, but are not limited to, ethylene diisocyanate, rrimethylene diisocyanate, tetramethylene diisocyanate, hexamethyiene diisocyanate (HDI), octamethylene diisocyanate, nonaraethylene diisocyanate, dimethylpentane diisocyanate, trimethylhexane diisocyanate, decaraethyiene diisocyanate, trimethylhexamethylene diisocyanate, undecane hi isocyanate, hexamethyiene triisocyanate, diisocyanato- (isocyanatomethyi)octane_s trimethyl-diisocyanato (isocyanatomethyl)octane, bis(lsocyanatoethyl) carbonate, bis(isocyanatoethyi)ether, isoeyanatopropyl- diisocyanatohexanoate, lysinediisocyanate methyl ester and lysmetriisocyanate methyl ester.

Examples of ethyienically unsaturated poiyisocyanates from which the isocyanate functional reactant may be selected include, but are not limited to, butene diisocyanate and butadiene diisocyanate. Aiicyclic poiyisocyanates from which the isocyanate functional reactant may be selected include, but are not limited to. isophorone diisocyanate (IPDI), cyclohexane diisocyanate, methylcyclohexane diisocyanate, bis(isocyanatoraethyl) cyclohexane, bis(isoeyanatocyclohexyl) methane, bis(isocyanatocyclohexyl) propane, bis(isocyanatocyclohexyi) ethane, and isocyanatomethyl-iisocyanatopropy!)- isocyanatomethyl bicycloheptane.

Examples of aromatic poiyisocyanates wherein the isocyanate groups are not bonded directly to the aromatic ring from which the isocyanate functional reactant may be selected include, but are not limited to, bisfisocyanatoethyl) benzene, tetramethylxylene diisocyanate, bis(isocyanato-methylethyl) benzene, bis(isocyanaiobutyl) benzene, bis(isoeyanatomethyl) naphthalene, bis(isocyanatomethyl)diphenyl ether, bis(isocyanatoethyl)phthalate, niesityiene triisocyanate and di(isocyanaiomethyi) furan. Aromatic poiyisocyanates, having isocyanate groups bonded directly to the aromatic ring, from which the isocyanate functional reactant may be selected include, but are not limited to, phenylene diisocyanate, ethylphenylene diisocyanate, isopropylphenylene diisocyanate, diniethylphenyiene diisocyanate, diethylphenylerse diisocyanate, diisopropylphenyiene diisocyanate, trimethyibenzetie triisocyanate, benzene triisocyanate, naphthalene diisocyanate, methylnaphthalene diisocyanate, biphenyl diisocyanate, ortho-tolidine diisocyanate, diphenylm ethane diisocyanate, bis(methyl-isocyanatophenyl) methane, bis(isocyanatophenyi) ethylene, dimethoxy-bipheny-diisocyanate, triphenylmethane triisocyanate, polymeric diphenylmethane diisocyanate, naphthalene triisocyanate, diphenylmethane-triisocyanate, methyldiphenylmethane pentaisocyanate, diphenylether diisocyanate, bi s(i socyanatopheny I ether) ethyleneglycol, bisfisoc yanatopheny iether) propyleneglycol, benzophenone diisocyanate, carbazole diisocyanate, ethylcarbazole diisocyanate and dichiorocarbazoie diisocyanate.

Examples of polyisocyanate monomers having two isocyanaie groups include, xylene diisocyanate, tetramethylxyiene diisocyanate, isophorone diisocyanate, bis(isocyanatocyclohexyl)methane, toluene diisocyanate (TDT), diphenylmethane diisocyanate (MDI), and mixtures thereof.

Commonly used prepolymers, isocyanaie functional polyols, include, hut are not limited to, polyether polyols, polycarbonate polyols, polyester polyols and po!yeaproiactone polyols. Commercial prepolymers, such as Adiprene® L213 a TDI, terminated polyether based (PTMEG), are readily available.

Further, the molecular weight of the prepolymers can vary widely, for example, having a number average molecular (Mn) of from 500 to 15,000, or from 500 to 5000, as determined by gel permeation chromatography (GPC) using polystyrene standards.

Classes of polyols thai may be used to prepare the isocyanaie functional prepolymers of the first coraponent of the two-component eornposition used to prepare the particulate crosslinked polyurethane include, but are not limited to: straight or branched chain alkane polyols, e.g., ethanediol, propanediol, propanediol, butanediol, butanediol, glycerol, neopeniyl glycol, trimethylolethane, trimethyloipropane, di-trimethylolpropane, erythritol, pentaerythritol and di-pentaerythritoi; polyalkyiene glycols, e.g., dk tri- and tetraethylene glycol, and di~, tri- and tetrapropylene glycol; cyclic alkane polyols, e.g., cyclopentanediol, cyciohexanediol, cyciohexanetriol, cyclohexanedimethanol, hydroxypropylcyclohexanoi and cyclohexanediethanol; aromatic polyols, e.g., dihydroxybenzene, benzenetrioi, hydroxybenzyl alcohol and dihydroxytoluene; bisphenols, e.g., isopropylidenediphenol; oxybisphenol, dihydroxybenzophenone, thiobisphenoi, pheno!phthlalein, bis(hydroxyphenyi)methane, (ethenediyl)bisphenol and suifonylbisphenol; haiogenated bisphenols, e.g., isopropylidenebis(dibromopheno!), isopropylidenebis(dichlorophenoi) and isopropylidenebis(tetrachlorophenoi); alkoxylated bisphenols, e.g., a!koxyiaied isopropyiidenediphenoi having from 1 to 70 a!koxy groups, for example, ethoxy, propoxy, and buioxy groups; and biseyclohexanols, which can be prepared by hydrogenating the corresponding bisphenols, e.g., isopropylidene-biscyelohexanol, oxybiscyclohexanol, thiobisc clohexanol and bis(hydroxycyciohexanol)methane, Additional classes of polyols thai may be used to prepare isocyanate functional polyurethane prepolymers include, for example, higher poiyalkylene glycols, such as polyethylene glycols having number average molecular weights (Mn) of, for example, from 200 to 2000; and hydroxy functional polyesters, such as those formed from the reaction of diols, such as butane dio!, and diacids or diesters, e.g., adipic acid or diethyl adipate, and having an Mn of, for example, from 200 to 2000. In an embodimeni of the present invention, the isocyanate functional polyurethane prepolymer is prepared from a diisocyanate, e.g., toluene diisocyanate, and a poiyalkylene glycol, e.g., poiy(tetrahydrofuran) with an M„ of 1000.

Additionally, the isocyanate functional polyurethane prepolymer may optionally be prepared in the presence of a catalyst. Classes of suitable catalysts include, but are not limited to, tertiary amines, such as triethylamine, and organomeialiic compounds, such as dibutyltin dilaurate.

In some exemplary embodiments, an abrasive filler may also form part of the water- insoluble foam particle 120 and/or water-insoluble foam matrix 1 10. This abrasive filler may include exemplary abrading particles that include, but are not limited to, particles of, for example, cerium oxides, silicon oxides, aluminum oxides, zirconia, iron oxides, manganese dioxides, kaolin clays, montmorillonite clays, and titanium oxides. Additionally, exemplary abrading particles may include, but are not limited to, silicon carbides and diamond.

Preferably, it is possible to manufacture urethane polymers for polishing pads with a single mixing step that avoids the use of isoeyanate-term mated monomers. With reference now to Figure 3, and as discussed above, in accordance with an exemplary embodiment of the present invention, a prepolymer is mixed in an open-air container with the use of a high- shear impeller. During the mixing process, atmospheric air is entrained in the mix by the action of the impeller, which pulls air into the vortex created by the rotation. The entrained gas bubbles act as nucleation sites for the subsequent foaming process, A blowing agent, such as water, is then added to the mix to create the reaction which produces the C(¾ gas responsible for cell growth, During this open-air mix and while in the liquid phase, other optional additives can be added to the mix such as surfactants or additional blowing agents, The coated particles are added and mixed in during this liquid phase. Finally, the prepolymer is reacted with a foaming agent such as, 4,4'-methyiene-bis~o~chloroaniiine [MBCA or MGCAJ. The MOCA initiates polymerization and chain extension, causing the viscosity of the mix to increase rapidly. There is a short time window after the addition of MOCA of about 1-2 minutes during which the viscosity of the mix remains low, called the "low-viscosity window/' The mix is poured into the mold during this window, Quickly after the pour, the window passes, and existing pores become effectively frozen in place. Although pore motion has essentially ended, pore growth continues, as CC½ continues to be produced from the polymerization reaction. The molds then oven cure to complete the polymerization reaction, typically 6-12 hours at 1 15 C.

After oven curing, the molds are removed from the oven, and allowed to cool. At this point, a cured moid (one formed without particles) cars be broken up into particles for use in a subsequent pad forming process. If the cured mold contains the coated particles, it may be sliced using a skiver. The slices can be made into circular or rectangular- shaped pads by cutting them to shape with a punch or cutting tool, after which an adhesive is usually applied to one side of the pad. The pad surface can then be grooved, if desired, on the polishing surface in a pattern such as a cross-hatched pattern (or any other suitable pattern). At that point, the pads are generally ready for use.

Also, in an exemplary embodiment of the present invention, the geometry or shape of grooves may comprise at least one of a square trough, a rounded trough, and a triangular trough. in addition to the specific embodiments disclosed, numerous physical configurations of various geometries to the polishing pad surface are contemplated in this disclosure.

In addition to the specific embodiments disclosed, any arrangement, combination, and/or application of water-soluble coated water-insoluble foam coated particles within a water-insoluble foam matrix applicable for a single pad would work for a plurality of pads stacked on each other. For example, a stacked pad may comprise one such pad 100 as disclosed herein as well as a typical pad.

In addition to the exemplary pad surface configurations, methods for forming these pads are herein disclosed. In an exemplary embodiment of the present invention, grooves can be created via any mechanical method capable of producing grooves in a polymer foamed polishing pad. in an exemplary embodiment of the present invention, grooves can be created with a circular saw blade, a punch, a needle, a drill, a laser, an air-jet, a water jet, or any other instrument capable of rendering grooves in the pad. Moreover, grooves can be made simultaneously with a multiple gang-saw jig, a multiple-drill bit jig, a multiple punch jig, or a multiple-needle jig. Chemical Foaming Agents

In an exemplary embodiment of the present invention, the polishing pad may be chemically configured to comprise a chemical foaming agent applied to the open-air mix while in the liquid phase, in an exemplary embodiment of the present invention, the chemical foaming agent comprises at least one of a hydroflourocarbon (HFC) or azeotrope of 2 or more hydrocarbon (HFCs), such as 1, 1, 1,3,3-pentailourobutane (HFC-365); 1,1,1,2- ietraflouroetbane (HFC- 134a), niethoxy-rtonafiuorobutane (HFE-7I 0Q) and a free radical initiator comprising an azorsltrile, such as 2,4-Dimeihyl, 2,2'~Azobis Pentanenitrile, Exemplary foaming agents include the HFCs Soikane® 365mfe and 134a (Solvay, Hannover, Germany), and free radical initiators Vazo 52 (Duponi, Wilmington, DE). One of reasonable skill in the art will recognize that, in addition to the specific embodiments disclosed, numerous chemical foaming agents can be incorporated into the polishing pad and are contemplated in this disclosure.

Cell openers

in an exemplary embodiment of the present invention, the chemical configuration comprises a ceil opener which promotes cell opening during the interaction of two cells in the liquid phase. Exemplary cell openers include, but are not limited to non-hyrdrolizabie polydimethylsiloxanes, pofyaikyleoxides. dimethylsiloxy, methylpolyethersiloxy, silicone copolymers, wherein the silicone copolymers can be Dabco DC-3043 or Dabco DC-3042 (Air Products, Allentown, PA).

Direct Introduction of Bubbles

In addition to chemical foaming agents and cell openers, it may be possible to directly introduce gas bubbles into the mix, during the mix process. For example, while the mix is still in the liquid state, such as before the addition of MOCA, or after the addition of MOCA but within the low-viscosity window, the output of a gas injector can be inserted directly into the open-air mix, causing the injection of more bubbles than would otherwise be introduced through the action of the impeller alone. Optionally, one could apply micro- filtration to the output end of a pump, such as a gas injector pump, to promote the formation of very small bubbles, such as those in the 1 -10 micron diameter range. In accordance with another exemplary embodiment of the present invention, a method of forming a pad includes the step of directly introducing gas bubbles into the air-mix in the liquid phase. This step of directly introducing gas bubbles may involve the selection of the size and quantity of bubbles. With reference to Figure 2, in one exemplary embodiment, polishing pad I 00 may be used in connection with a polishing table, a slurry, and a platen for holding the object to be polished. The pad may be moved relative to the object being polished. During the polishing process, the pad may self condition such that polishing may occur for a longer period of time than for a traditional polishing pad that is not so configured, in one exemplary embodiment, the polishing pad is never reconditioned.

In an exemplary embodiment, the embedding of these coated particles facilitates reduced conditioning or may eliminate conditioning of the pad entirely because, as the particles are exposed during polishing, the water-soluble coating wiii cause those particles to gradually become detached from the surface of the pad. Stated another way, the water- soluble coating surrounding exposed particles may dissolve and release the particles from the pad. This action generates new holes in the surface and eventually exposes yet further coated particles. Such self conditioning may reduce the need to "rake" the pad, and cause the pad to last longer.

The detailed description of exemplary embodiments of the invention herein shows various exemplary embodiments and the best modes, known to the inventors at this time, of the invention are disclosed. These exemplary embodiments and modes are described in sufficient detail to enable those skilled in the art to practice the invention and are not intended to limit the scope, applicability, or configuration of the invention in any way, Rather, the following disclosure is intended to teach both the implementation of the exemplary embodiments and modes and any equivalent modes or embodiments thai are known or obvious to those of reasonably skill in the art. Additionally, all included figures are non-limiting illustrations of the exemplary embodiments and modes, which similarly avail themselves to any equivalent modes or embodiments that are known or obvious to those of reasonable skill in the art.

Other combinations and/or modifications of structures, arrangements, applications, proportions, elements, materials, or components used in the practice of the instant invention, in addition to those not specifically recited, can be varied or otherwise particularly adapted to specific environments, manufacturing specifications, design parameters, or other operating requirements without departing from the scope of the instant invention and are intended to be included in this disclosure.

Unless specifically noted, it is the Applicant's intent that the words and phrases in the specification and the claims be given the commonly-accepted generic meaning or an ordinary and accustomed meaning used by ihose of ordinaiy skill in ihe applicable arts. In the instance where these meanings differ, the words and phrases in the specification and the claims should be given the broadest possible, generic meaning. The words and phrases in the specification and the claims should be given the broadest possible meaning, if any other special meaning is intended for any word or phrase, the specification will clearly state and define the special meaning.

Claims

CLAIMS What is claimed is:

1. A polishing pad comprising:

a water-insoluble polymeric foam matrix; and

a plurality of coated particles, wherein said plurality of coated particles each comprise water-insoluble polymeric foam particles coated with a water-soluble component.

2. The polishing pad of claim I , wherein said water-insoluble polymeric foam particles have a diameter between about 5 and 2.000 microns.

3. The polishing pad of claim 1, wherein said water-insoluble polymeric foam particles are coated over about 5% to 90% of the surface area of said water-insoluble polymeric foam particles.

4. The polishing pad of claim 1. wherein said coated particles comprise about 10% to 90% by volume of the polishing pad.

5. The polishing pad of claim 1, wherein said water-soluble component comprises at least one of: a water-soluble polymer, a surfactant, an etchant, a pH buffer, an acid, and a base,

6. The polishing pad of claim i , wherein the pad comprises open cells, and wherein the open cell content of the water-insoluble polymeric foam particle is about 5% to about 75%.

7. The polishing pad of claim 1 , wherein the water-soluble component of the particle coating may be between 50% and 100% soluble.

8. The polishing pad of claim 7, wherein the water-insoluble polymeric foam particles have a bulk density of about 0.2 to 0.85 g/cm^A3.

9. The polishing pad of claim 1 , wherein the water-insoluble polymeric foam matrix has a bulk density of 0,2 to 0J5 g/cm^A3.

10. A method of producing a self-conditioning polishing pad comprising:

forming a plurality of coated water-insoluble polymeric foam particles;

preparing a prepolymer solution;

mixing said prepolymer solution in an open-air mix, wherein at least one of a gas bubble and a blowing agent are added to said open-air mix;

adding said plurality of coated water-insoluble polymeric foam particles to the mix; adding a polymerizing agent to the mix;

allowing the mixture to foam; pouring said mixture into an open mold;

curing said mixture to form a foam bun; and

forming a foamed polishing pad out of said foam bun by slicing individual pads out of said foam bun.

1 1. The method of claim 10. wherein said plurality of coated water-insoluble polymeric foam particles comprise a plurality of water-insoluble polymeric foam particles that are coated with a water-soluble component.

12. The method of claim 1 1, wherein said plurality of water-insoluble polymeric foam particles are coated over 5% to 90% of their surface area.

13. The method of claim. 1 i, vy here in said plurality of water-insoluble polymeric foam particles are between 5 to 2000 microns in diameter.

14. The method of claim 1 1 , wherein said plurality of water-insoluble polymeric foam particles are formed by cryogenically grinding a larger water-insoluble polymeric foam object to form particles.

15. The method of claim 10, wherein said plurality of coated water-insoluble polymeric foam particles are coated by spray coating.

16. The method of claim 15, wherein said plurality of coated water-insoluble polymeric foam particles are dried and clarified.

17. The method of claim 10, comprising creating a groove with a mechanical device in the pad.

18. The method of claim 10, comprising:

adding at least one of a chemical foaming agent, wherein said chemical foaming agent allows for formation of a plurality of small pores in the foam, and a ceil opener, wherein said ceil opener allows for formation of a plurality of small cells in the foam, to said prepolymer solution; and

adding at least one abrading particle to said prepolymer solution.

19. The method of claim 10, wherein said water-insoluble foam particles are the product of mixing a prepolymer, a curing agent, a surfactant, and a foaming agent.

20. The method of claim 10, wherein said water-insoluble foam particles are the product of mixing a prepolymer, a curing agent, a surfactant, a foaming agent, and an abrasive filler.

21. The method of claim 10, wherein said water-insoluble foam matrix is the product of mixing a prepolymer, a curing agent, a surfactant, and a foaming agent.

22. The method of claim 10, wherein said water-insoluble foam matrix is the product of mixing a prepolymer, a curing agent, a surfactant, a foaming agent, and an abrasive filler.