WO2013188296A1

WO2013188296A1 - Composition and method for polishing molybdenum

Info

Publication number: WO2013188296A1
Application number: PCT/US2013/044981
Authority: WO
Inventors: Pankaj Singh; Lamon Jones
Original assignee: Cabot Microelectronics Corp
Current assignee: CMC Materials LLC
Priority date: 2012-06-11
Filing date: 2013-06-10
Publication date: 2013-12-19
Anticipated expiration: 2014-12-11
Also published as: CN108977173A; EP2859059B1; JP2015525483A; EP2859059A1; US20150221520A1; KR102136432B1; JP6272842B2; EP2859059A4; CN104395425A; KR20150032530A; US20130327977A1

Abstract

The present invention provides compositions and methods for polishing a molybdenum metal-containing surface. A polishing composition (slurry) described herein comprises an abrasive concentration of an inorganic particulate abrasive material (e.g., alumina or silica) suspended in an acidic aqueous medium containing a water soluble surface active material and an oxidizing agent. The surface active material is selected based on the zeta potential of the particulate abrasive, such that when the abrasive has a positive zeta potential, the surface active material comprises a cationic material, and when the particulate abrasive has a negative zeta potential, the surface active material comprises an anionic material, a nonionic material, or a combination thereof.

Description

i

COMPOSITION AND METHOD FOR POLISHING MOLYBDENUM

FIELD OF THE INVENTION

(0001) The invention relates to the semiconductor manufacturing arts. More

particularly, this invention relates to compositions and methods for polishing a molybdenum surface.

BACKGROUND OF THE INVENTION

[ΘΘ02] Molybdenum metal is utilized in a number of industrial applications, including microelectronic devices (e.g., for interconnects, photo masks, and other uses). In such applications, molybdenum, initially is utilized in an excess amount, and then at least some molybdenum must be removed by polishing or lapping, in a controlled manner, to achieve surface properties suitable e.g., for semiconductor device manufacture.

|0003) Abrasive materials are commonly utilized in polishing and lapping of metals. In such applications, abrasive particles are suspended in a liquid medium, such as water, sometimes with the aid of surfactant as a. dispersing agent. Polishing of metallic molybdenum surfaces often is accomplished using abrasives of varying sizes to obtain a desired surface roughness. Currently used abrasives generally require multiple steps to polish molybdenum surfaces, which can mean using multiple machines and or parts and abrasive changes, which can adversely affect the processing time for each part.

(0004) Abrasive materials typically are suspended in a liquid carrier, such as water or an aqueous medium containing water. When the abrasive is suspended in the liquid earner, it preferably is colloidally stable. The term "colloid" refers to the suspension of abrasive particles in the liquid carrier. "Colloidal stability" refers to the maintenance of that suspension over time. In the context of this invention, an abrasi ve suspension is considered colloidally stable if, when the silica is placed into a 100 mL graduated cylinder and allowed to stand without agitation for a time of 2 hours, the difference between the concentration of particles in the bottom 50 mL of the graduated cy linder (] B| m terms of g/mL) and the concentration of particles in the to 50 mL of the graduated cylinder ([T] in terms of g/mL) divided by the total concentration, of particles in the abrasive composition (|C) in terms of g/mL) is less man or equal to 0.5 (i.e., ([Bj - T])/[C] < 0.5). The value of ( Bj-[T])/[Cj desirably is less than or equal to 0.3, and preferably is less than or equal to 0.1.

{0005] There is an ongoing need for new compositions and methods tor polishing molybdenum surfaces. The present invention addresses this need. BRIEF SUMMARY OF THE INVENTION

[0006] The present invention provides a method of polishing a molybdenum metal- containing surface comprising abrading the surface with a polishing slurry comprising an abrasive concentration of an inorganic particulate abrasive material, such as alumina or silica, suspended in an acidic aqueous medium containing a water soluble surface active material and an oxidizing agent (e.g., hydrogen peroxide).

[ΘΘ07{ In one embodiment, the aqueous CMP composition has a pH in the range of 3 to 6. The water soluble surface active material can be a cationic material, such as a cationic polymer or cationic surfactant. Alternatively, the surface active material can be an anionic material, a nonionic material, or a combination thereof. The choice of the surface active material is based on the zeta potential of the particulate abrasive, such that when the abrasive has a positive zeta potential (e.g., when alumina or an aminosiiane-treated silica is used), the surface active materia! comprises a cationic material, and when the particulate abrasive has a negative zeta potential (e.g., when native silica, such as fumed silica, is used), the surface active material comprises an anionic material, a nonionic material, or a combination thereof.

J 0008] For example, the cationic material can be a cationic polymer, or a cationic surfactant (e.g., a tetraalkyla momum compound). An example o f a cationic polymer useful in the compositions and methods described herein is a poly(mei¾acryloxyethyl trimethylammonium) ha^'Hde (e.g., a chloride).

[0009} In one preferred embodiment, the aqueous CMP comprises an aqueous carrier having a pH in the range of 3 to 6, and contains, at point -of~use, 0.5 to 6 percent by weight (wt¾) of a particulate abrasive (i.e., silica, or alumina), 25 to 5,000 parts-per-million (ppm) of the water soluble surface active material, and 0.1 to 1.5 wt% of the oxidizing agent.

[ΘΘ10] In another aspect, the present invention provides a CMP method for polishing a molybdenum-containing substrate. The method comprises the steps of contacting a surface of the substrate with a polishing pad and an aqueous CMP composition as described herein, and causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface between the pad and the substraie for a time period sufficient to abrade at least a portion of the moiybdemim from the substraie. BRIEF DESCRIPTION OF THE DRAWINGS

|00J J j FIG. .1 provides a graph of Mo removal rate (RR) for CMP compositions comprising various concentrations of cationic polymer (bars, left axis), as well as a plot of average roughness (boxes, right axis) obtained by polishing Mo wafers with each composition.

DETAILED DESCRIPTION OF THE INVENTION

[0012} The present invention provides a method of polishing a molybdenum metal- containing surface comprising, consisting essentially of or consisting of abrading the surface with a polishing slurry comprising a abrasive concentration of an inorganic particulate abrasive material (alumina or silica) suspended in an acidic aqueous medium containing a water soluble surface active agent and an oxidizing agent.

(0013) The present invention also provides a polishing composition comprising, consisting essentially of, or consisting of an acidic aqueous carrier containing an inorganic particulate abrasive material (e.g., silica or aluminaX a water soluble surface active agent and an oxidizing agent. The surface active material is selected based on the zeia potential of the particulate abrasive, such that when the abrasive has a positive zeta potential, the surface active material comprises a cationic material, and when the particulate abrasive has a negative /eta potential, the surface active material comprises an anionic material, a nonionic material or a combination thereof.

[ΘΘ14] The aqueous carrier can comprise, consist essentially of or consist of any aqueous solvent, e.g., water, an aqueous alcohol (e.g., aqueous methanol, aqueous ethanol, aqueous ethylene glycol, and the like), and the like. Preferably, the aqueous carrier comprises deionked water.

[0015] The particulate abrasive .materials useful in the CMP compositions of the invention include alumina (e.g., alpha-alumina), which has a positive zeta potential, and silica, which has a negative zeta potential in its .native state, but which can be surface- modified by treatment with an aminosilane to have a positive zeta potential, A preferred type of alumina for use in the CMP composition of the invention is alpha-alumina. One preferred type of silica for use in the CMP composition of the invention is untreated (i.e., "native") fumed silica having a negative zeta potential. In other preferred embodiments, the abrasive comprises silica, in which the surface of the silica particles have been treated with an aminosilane such as bis(trimethoxysilylpropyl)amine, e.g., SILQUEST A 1170

(Crompton OSi Specialties), or a similar reactive aminosilane to adjust the zeta potential from negative to posiiive, by bonding basic amino groups to the surface of t.be silica particles and thereby neutralize acidic SiOH groups on the particle surface. Preferably; the surface-treated silica is ireaied with sufficient aminosilane to provide a highly positive zeta potential in the range of 5 to 50, if a cationic polymer or surfactant is to be included in the CMP composi tion.

(0016) The abrasive material preferably has a mean particle size In the range of 50 nra to 150 am, more preferably 90 nm to 120 nm. ^'Preferably, the abrasive material is suspended in an aqueous medium at a concentration in the range of 0.5 to 6 wt% at poinl-of- iise. For silica, the abrasive concentration preferably is in the range of 2 to wt%. For alumina (e.g., alpha-alumina) the concentration of abrasive preferably is in the range of 0.5 to 3 wl%. As used herein, the phrase "point of use" refers to the concentration of a given component that will be used directly in a CMP process, without further dilution. The point of use concentration generally is achieved by dilution of a more concentrated composition, (e.g., just before or within a few days prior to use).

[00J 7] The water-soluble surface active materials useful in the CMP compositions of the invention are selected based on the zeta potential of the particulate abrasive included In the composition. As described herein, cationic polymers aod/or surfactants are used with abrasives having a positive zeta potential, such as ceria and aminosilane-freated colloidal silica. Optionally, the cationic material can he combined with a nonionic polymer or surfactant, if desired. Anionic and/or nonionic surface active materials are utilized when the abrasive has a negative zeta potential, such as native colloidal silica.

[0018] Cationic polymers useful in the compositions and methods of the present invention inclu.de homopolymers of cationic monomers, e.g., a

poly(diallyldimethylammonium) halide such as poly diallyldimetbylammonium) chloride (polyDADMAC), a poly(memacryloyloxyethyltrimemylammonium) halide such as poly methacryloyloxyethyltximethylammonium) chloride (polyMADQUAT), and the like. In addition, the cationic polymer can be a copolymer of cationic and nonionic monomers (e.g., alkylaerylates, alkylmethacrylates, acryfaraide, styrene, and the like), such as poly(acrylamide-co-diallykHmethylammoniam) chloride. Some other non-limiting examples of such cationic polymer include poiyeihyleneimine, eihoxylated

polyemyieneimine, poly(diallyldimethylainmonium) halide, poiyCamidoamine),

polytmethacryioyloxyethyldimethylainmoniu n) chloride, poly(vinylpyrroIidone), po.ly(vi.ny.Hmidazole), poly(v.inylpyridine), and poly(vinylamine). A preferred cationic polymer for use in the CMP compositions of the invention is a poly(methacryloyloxyeihyl trimethyiammonium) lialide (e.g., chloride), such as the polymer commerciall available from Alco Chemical Inc. under the tradename A^'LCO 4773. Other suitable cationic materials include cationic surfactants, such as tetraalkyiammonhim compounds, e.g., hexadecyUriroew ylaramom^" um bromide, also known as cetyltrimethylammonium bromide; CTAB), 1 -decyitrimelhylammomrn chloride (DPC), and the like.

[ΘΘ19} The cationic polymer can have any suitable moiecuiar weight. Typically, the polishing composition comprises a cationic polymer having a molecular weight of 5 kiloDalatons (k.Da) or more (e.g., 10 k.Da or more,. 20 kDa or more, 30 k.Da or more, 40 kDa or more, 50 kDa or more, or 60 kDa or more) cationic polymer. The polishing composition preferably comprises a cationic polymer having a molecular weight of 100 kDa or less (e.g., 80 kDa or less, 70 kDa or less, 60 kDa or less, or 50 kDa or less). Preferably , the polishing composition comprises a cationic polvmer having a molecular weight of 5 kDa to 1 0 kDa (e.g., 10 kDa to 80 kDa, 10 kDa to 70 kDa, or 15 kDa to 70 kDa.

J0020{ Anionic poiymers useful in the compositions and methods of the present invention include, for example, homopoJymers such as polyacrylic acid (PAA),

polymethacrylic acid (PMAA), polytnalek acid (PMA), poiy(2-aerylaraido-2- .meihylpropanestdfonate (polyAMPS), and the like, as well as copolymers of anionic and nonionic monomers, such as polyi acrylic acid-co-meihacryiic acid), polyi acrylic acid-co-2- acryiam.iilo-2-meth.yi-propanesuifonic acid), and the like. The anionic polymers can be utilized in the acidic form or as salts (e.g., sodium salts). The actual ionic character of the anionic polymer (i.e., fully ionized or partially ionized) will depend upon the pH of the CMP composition, as is well known in the art. Preferably, anionic poiymers utilized in the compositions and methods of the present invention have an average molecular weight of 100 kDa or less, for example, 0 kDa or less, or in the range of 1 to 10 kDa.

f 0021 J onionic polymers useful in the compositions and methods of the present invention include, for example, polyacrylamide (PAM) homopolymers, and. copolymers of acrylamide with one or more other nonionic monomer such as raethacrylamide, Λ'- vinylpyrrolidoue, and the like. Preferably, nonionic polymers utilized in the compositions and methods of the present invention have an average molecular weight of 1 0 kDa or less, for example, 1 kDa or less, or in the range of 1 to 10 kDa.

(00221 In some preferred embodiments the water-soluble surface active material (e.g., polymer or surfactant) is present in the composition at a concentration in the range of 25 to 5,000 paris-per- illion (ppro), e.g., .100 to 1.000 ppm.

|0023j The abrasive desirably is suspended in the CMP composition, more specifically in the aqueous component of the CMP composition, and is colloidally stabie. The term colloid refers to the suspension of abrasive pariicies in the liquid carrier. Colloidal stability refers to the maintenance of that suspension over time.

[00241 in some embodiments, an alumina abrasive or an aminosilane-treated colloidai siiica abrasive is used in conjunction with a cationic materia i (e.g., a polymer or surfactant) in the CMP composition of the present invention. Alumina and aminosilane-treated colloidal, silica have positive zeta potentials, which complement the zeta potential of a cationic polymer, and allow both components to exist within the same composition, without precipitation of components, inclusion of a cationic polymer such as ALCO 4773 in the CMP composition reduces surface defects on the molybdenum being polished, relative to CMP compositions lacking the cationic material.

[0025} In other embodiments, the abrasive material component of the CMP composition comprises native silica (e.g., fumed silica) having a negative zeta o ential, preferably in conjunction with an anionic polymer and/or a nonionic polymer in the CMP composition of the present invention. PAA and PAM, for example, advantageously form colloidally stable slurries with silica, due to the negative zeta potential of the silica. Some non-ionic polymers such as lo molecular weight polyethylene glycols, polyvinylpyrrolidone or

polyvinylalcohol typically do not form colloidally stable slurries in the CMP composition, of the present invention, at least when utilized on their own. Anionic polymers such as PAA or a nonionic polymers such as PAM reduce surface defects on the molybdenum surface being polished,

{0026] The polishing composition has an acidic pH, e.g., in the range of 3 to 6, The pH of the polishing composition can be achieved and/or maintai ned by any sui tabl e means. For example, the pti can be maintained through the use of a suitable buffer, if desired. In addition, the other components of the composition (e.g., the abrasive and the surface active agent) also help to establish and maintain the pH. More specifically, the polishing composition can further comprise a pH adjuster, a p.H buffering agent, or a combination thereof. The pH adjuster can comprise, consist essentially of, or consist of any suitable pH- adjusting compound. For example, the pH adjuster can be the acid of the polishing

composition. The pH buffering agent can be any suitable buffering agent, for example, phosphates, acetates, borates, sulfonates, carboxylates, ammonium salts, and the like. The polishing composition can comprise any suitable amount of a pH adjuster and/or a pH buffering agent, provided such amount ia sufficient to achieve and/or maintai ti the desired pH of the polishing composition, e.g., within, the ranges set forth herein.

J0027j The polishing composition also comprises an oxidizing agent, which can be any suitable oxidizing agent for one or more materials of the substrate to be polished with the polishing composition. Preferably, the oxidizing agent is selected from the group consisting of a bromate, a bromite, a chlorate, a chlorite, hydrogen peroxide, a hypochlorite, an iodate, a monoperoxysultate, a monoperoxysuJfite, a nionoperoxyphosphaie, a

nionoperoxyhypophosphate, a monoperoxypyrophosphate, an organo-halo-oxy compound, a periodate, a permanganate, peroxyacetk acid, a ferric salt (e.g., ferric nitrate), and a combination of two or more thereof. The oxidizing agent can be present in the polishing composition in any suitable amount. Typically, the polishing compositio comprises 0.01 wt. % or more (e.g., 0.02 wt. % or more, 0.1 wt. % or more, 0.5 wt, % or more, or j wt. % or more) oxidizing agent. The polishing composition preferably comprises 2 wt% or less (e.g., 0.1 to 1.5 t% at point of use) of the oxidizing agent when a "strong" oxidizer is used. Hydrogen peroxide is a particularly preferred strong oxidizing agent. For weaker oxidizing agents, such as ferric nitrate, a higher concentration (e.g., up to 10 wt% or more) may be required or desired.

|ΘΘ28] It will be appreciated that many of the aforementioned compounds (e.g. , polymers, surfactants, acids, buffering agents) can exist in the form of a salt (e.g., a metal salt, an ammonium salt, or the like), an acid, or as a partial salt. Furthermore, certain compounds or reagents may perform more than one function. For example, some compounds can function both as a chelating agent and an oxidizing agent (e.g., certai ferric nitrates and the like).

[0029] The polishing slurries of (he present invention also can be provided as a concentrate, which is intended to be diluted with an appropriate amount of aqueous solvent (e.g., water) prior to use. In such an embodiment, the polishing slurry concentrate can include the various components dispersed or dissolved in aqueous solvent in amounts such that, upon dilution of the concentrate with an appropriate amount of aqueous solvent, each component of the polishing composition will be present in the polishing composition in an amount, within the appropriate range for use.

}t)i)30| The polishing slurries of the invention can be prepared by an suitable technique, many of which are known to those skilled in the art. The polishing slurry can be prepared in a batch or continuous process. Generally, the polishing slurry can be prepared by combining the components thereof in any order. The term "component" as used herein includes individual ingredients (e.g., abrasive, polymer, surfactant, acids, bases, buffers, oxidizing agents, and the like), as well as any combination of ingredients. For example, the abrasive can be dispersed in water, the surface active material, and any other additive material can be added, and mixed by any method that is capable of incorporating the components into the polishing slurry. The pH can be further adjusted, if desired, at any suitable time by addition of an acid, base or a buffer, as needed. Preferably, the oxidizing agent in assed to the composition shortly before use (e.g., a few minutes to a few days before use).

(t)t)31| The CMP methods of the present invention are particularly suited for use in conjunction with a chemical-mechanical polishing apparatus. Typically, the CMP apparatus comprises a platen, which, when in use, is in motion and has a velocity that results from, orbital, linear, and/or circular motion, a polishing pad in contact with the platen and moving with the platen when in motion, and a carrier that holds a substrate to be polished in contact with the pad and moving relative to the surface of the polishing pad. A CMP composition is typically pumped onto the polishing pad to aid in the polishing process. The polishing of the substrate is accomplished by the combined abrasive action of the moving polishing pad and the CMP composition of the invention present on the polishing pad, which abrades at least a portion of the surface of the substrate, and thereby polishes the surface.

[0032] A substrate can be planamed or polished with a CMP composi tion of the invention using any suitable polishing pad (e.g., polishing surface). Suitable polishing pads include, for example, woven and non-woven polishing pads. Moreover, suitable polishing pads can comprise any suitable polymer of varying density, hardness, thickness,

compressibility, ability to rebound upon compression, and compression modulus. Suitable polymers include, for example, polyvinylchloride, polyvinylfluoride, nylon, flitorocarbon, polycarbonate, polyester, polyacrylate, polyeiher, polyethylene, polyamide, polyurethane, polystyrene, polypropylene, cofornied products thereof, and mixtures thereof.

|0033j Desirably, the CMP apparatus further comprises an in situ polishing endpomt detection system, many of which are known in the art. Techniques for inspecting and monitoring the polishing process by analyzing light or other radiation reflected from a surface of the workpiece are known hi the art. Such methods are described, for example, in U.S. Patent 5,1 6,353 to Sandhu er a!, , U.S. Patent 5,433,651 to Lostig el a I., U.S. Patent 5,949,927 to Tang, and U.S. Patent 5,964643 to Birang t l Desirably, the inspection or monitoring of the progress of the polishing process with respect to a workpiece being polished enables the determination of the polishing end-point, i.e., the determination of when to terminate the polishing process with respect to a particular workpiece.

[0034] The following non-limiting examples are provided t illustrate preferred embodiments of the methods of the present invention.

EXAMPLE i

[0035) Sintered molybdenum wafers (2-inch square) were polished for 20 minutes with CMP shinies on a BYPREZ Model 15 polisher with an EPIC D 100 polishing pad

(concentric grooving; 1. minute ex situ conditioning between wafers with a TBW

conditioner) at a down force (DF) of 9.4 pounds-per-square inch (psi), a platen speed of 75 revoluticns-per-minute (rpm) and a slurry flow rate of 75 miHiliiers-per-ininute (mL/min).

[6036] Polishing slurries containing 2, 6, and 12 wt% alpha-alumina in water at pH 4 provided Mo removal rates (RR) of 490, 650, and 830 nanometers-per-hour (nm hr), respectively, indicating the increasing abrasive concentration leads to higher removal rates. The Mo surfaces exhibited an average roughness (Ra) of 290 to 325 Angstroms (A). Use of 5 wt% fumed silica in place of alumina lead to a Mo removal rate of 210 nm/hr at pH 4. Decreasing the pH to 2.3 increased the RR to 240 nra hr with the silica slurry, whereas increasing the pH to 8 and 10 lead to removal rates of 180 to 190 nm/hr. Electrochemical evaluation indicated that the silica slurries exhibited an oxidation potential in the corrosion region at all pH values (see Table 1 ).

Table I .

With Abrasion After abrasion

Slurry pH E (mV) (μΑ/cni) E_{e iv} {mV) ^A cm')

2J ^5 5 ^25 2

8.0 -693 14 -689 1 1

[ 0037] Addition of an oxidizing agent (14 to 140 ppm ferric nitrate, 0.2 wt% hydrogen peroxide, 0.2 wi% potassium p riodate, or 0.2 wt% potassium permanganate) to the slurries resulted in higher oxidation and corrosion and unsuitable surface rooghness characteristics.

EXAMPLE 2 [0038] The effectiveness of corrosion inhibitors in abrasive slurries containing oxidizing agents was evaluated. Slurries comprising 2 wt% alpha-alumina and 0.2 wt. hydrogen peroxide at pH 4 were evaluated with traditional inhibitors used in copper polishing (glycine, 1 ,2,4-triazole, benzoiria ole, 5-aminotetrazole) still afforded higher than desirable surface roughness. Fumed silica slurries showed similar results with glycine, lysine, and cationic polymer (polyMADQUAT; ALCO 4773).

[0039] In contrast to the results with fumed silica, aipha-aiumina slurries including polyMADQUAT (50 to 1000 ppm) provided suitable Mo removal rates (R.R; 1700 to 2700 nm/hr) and suitable roughness (R.a; 225 to 350 A (see FIG. .1). For comparison, an alpha- alumina composition having the same formulation, but without the polyMADQU AT (first bar in FIG. I ), exhibited heavy surface staining and corrosion, resulting in an unacceptably rough surface beyond the scale of the plot in FIG. ! .

[0040] These results demonstrate that addition of a water sol uble surface active m aterial to polishin compositions comprising an abrasive and an oxidizing agent can provide unexpected improveme ts in surface roughness when the surface active agent is selected to complement the zeta potential of the abrasive (e.g., cationic polymer plus positive zeta potential abrasive), compared to slurries without added surface active agent, or with surface active agent and incompatible zeta potential (e.g., silica with polyMADQUAT).

Claims

I ! CLAIMS

1. Aii aqueous chemical-mechanical polishing (CMP) composition for polishing a molybdemjrai-contaming substrate, the composition comprising an aqueous carrier having a pH in the range of 3 to 6 and containing, at. point of use:

(a) a particulate abrasive selected from the group consisting of a silica abrasive and an alumina abrasive;

(b) a water soluble surface active material; and

(c) an oxidizing agent;

wherein the surface active materia! is selected based on the zeta potential of the particulate abrasive, such that, when the abrasive has a positive zeta potential, the surface active material comprises a cationic material, and when the particulate abrasive has a negative eta. potential, the surface active material comprises art anionic material, a nonionic material, or a combination thereof.

2. The CMP composition of claim I wherein, the particulate abrasive comprises alpha-alumina and the surface active agent is a cationic material

3. The CMP composition of claim 2 wherein the cationic material is a cationic polymer.

4. The CMP composition, of claim 3 wherein the cationic polymer comprises a po.ly(methacryloxyethy.Urimethylammonium) haii.de.

5. The CM composition of claim 3 wherein oxidizing agent comprises hydrogen peroxide.

6. The CMP composition of claim I. wherein the particulate abrasive comprises silica and the surface active .material is an anionic material, a nonionic material or a combination thereof,

7. The CMP composition of claim 6 wherein the surface active material, comprises a polyiaery!ic acid), a polyaerylatnide. or a combination thereof.

8. The CMP composition of claim 6 wherein oxidizing agent comprises hydrogen peroxide.

9. The CMP composition of claim I. wherein the particulate abrasive comprises an aminosilane surface-treated silica having a positive zeta potential, and the surface active material comprises cationic material,

10. The CMP composition of claim 9 wherein the cationic material, is a cationic polymer.

1 1. The CMP composition of claim 10 wherein the cationk polymer comprises a po).y(methacryIoxyethyl trimethylammoni m) !iaiide.

12. The CMP composition of claim 9 wherein oxidizing agent comprises hydrogen peroxide.

13. The CMP composition of claim 1 wherein oxidizing agent comprises hydrogen peroxide.

14. An aqueous chemical-mechanical polishing (CMP) composition for polishing molybdenum, the composition comprising an aqueous carrier having a pH in the range of 3 to 6 and containing, at point of use:

(a) 0.5 to 6 wt% of a particulate abrasi ve selected from the group consisting of a silica abrasive and an alumina abrasive;

(b) 25 to 5,000 ppm of a water soluble surface active material; and

(c) 0.1 to 1 .5 wt% of an oxidizing agent,

wherein the surface active material is selected based on the zeta potential of the particulate abrasi ve, such that when the abrasive has a positi ve zeta potential, the surface active material comprises a cationic material, and when the paniculate abrasive has a negative zeta potential, the surf ace active material comprises an anionic material, a nonionic material, or a combination thereof.

1 5. The CMP composition of claim .1 wherein the particulate abrasive

comprises alpha-alumina or an aminosiiane surface-treated silica, and has a positive zeta potential and the water soluble surface active material comprises a

polyCmethacryloyiox yethyl trimethy lammoni urn) halide.

16. The CMP composition of claim 15 wherein oxidizing agent comprises hydrogen peroxide.

17. The CM P composition of claim 14 wherein the particulate abrasive comprises a siliea having a negative zeta potential, and the water soluble surface active material, comprises a poly( acrylic acid), a poiyaerylamide, or a combination thereof.

1 . The CMP composition of claim 17 wherein oxidizing agent comprises hydrogen peroxide,

1 . A chemical-mechanical polishing (CMP) method for polishing a

molybdenum-containing substrate, the method comprising the steps of:

(a) contac ting a surface of the substra te with a polishing pad and an aq ueous CMP composition of claim 1 ; and (b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composi tion in contact with the surface between the pad and the substrate for a time period sufficient to abrade at ieasi a portion of the molybdenum from the substrate.

20. A chemical-mechanical polishing (CMP) method for polishing a

molybdenum-containing substrate, the method comprising the steps of:

(a) contacting a surface of the substrate with a polishing pad and air aqueous CMP composition of claim 14; and

(b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the molybdenum from the substrate.