(19)
(11)EP 2 093 790 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
24.06.2020 Bulletin 2020/26

(21)Application number: 09152377.9

(22)Date of filing:  09.02.2009
(51)Int. Cl.: 
H01L 21/321  (2006.01)
C09G 1/04  (2006.01)
C09G 1/02  (2006.01)

(54)

LOW-STAIN POLISHING COMPOSITION

FLECKENARME POLITURZUSAMMENSETZUNG

COMPOSITION DE POLISSAGE EMPÊCHANT LES TÂCHES


(84)Designated Contracting States:
DE FR

(30)Priority: 22.02.2008 US 71000

(43)Date of publication of application:
26.08.2009 Bulletin 2009/35

(73)Proprietor: Rohm and Haas Electronic Materials CMP Holdings, Inc.
Newark, DE 19713 (US)

(72)Inventors:
  • THOMAS, Terence M.
    Newark, DE 19711 (US)
  • WANG, Hongyu
    Wilmington, DE 19808 (US)

(74)Representative: Kent, Venetia Katherine 
Patent Outsourcing Limited 1 King Street
Bakewell Derbyshire DE45 1DZ
Bakewell Derbyshire DE45 1DZ (GB)


(56)References cited: : 
WO-A1-03/053602
US-A1- 2006 160 475
WO-A2-2004/101221
US-B2- 7 086 935
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND OF THE INVENTION



    [0001] The invention relates to chemical mechanical polishing (CMP) of semiconductor wafer materials and, more particularly, to CMP compositions and methods for polishing metal interconnects on semiconductor wafers in the presence of dielectrics or barrier materials.

    [0002] Typically, a semiconductor wafer is a wafer of silicon with a dielectric layer containing multiple trenches arranged to form a pattern for circuit interconnects within the dielectric layer. The pattern arrangements usually have a damascene structure or dual damascene structure. A barrier layer covers the patterned dielectric layer and a metal layer covers the barrier layer. The metal layer has at least sufficient thickness to fill the patterned trenches with metal to form circuit interconnects.

    [0003] CMP processes often include multiple polishing steps. For example, a first step removes excess interconnect metals, such as copper at an initial high rate. After the first step removal, a second step polishing can remove metal that remains on the barrier layer outside of the metal interconnects. Subsequent polishing removes the barrier from an underlying dielectric layer of a semiconductor wafer to provide a planar polished surface on the dielectric layer and the metal interconnects.

    [0004] The metal in a trench or trough on the semiconductor substrate provides a metal line forming a metal circuit. One of the problems to be overcome is that the polishing operation tends to remove metal from each trench or trough, causing recessed dishing of such metal. Dishing is undesirable as it causes variations in the critical dimensions of the metal circuit. To reduce dishing, polishing is performed at a lower polishing pressure. However, merely reducing the polishing pressure would require that polishing continue for a lengthened duration. However, dishing would continue to be produced for the entire lengthened duration of polishing, thus producing little gain in performance.

    [0005] U.S. Patent No. 7,086,935 (Wang) describes the use of an abrasive-free copper formulation containing methyl cellulose, an acrylic acid/ methacrylic acid copolymer, benzotriazole (BTA) and miscible solvent for patterned wafers. This formula is capable of removing and clearing copper with low copper dishing, but during rapid polishing, it precipitates a green Cu-BTA compound on the polishing pad and wafer. These precipitates require a post-polishing cleaning of the polishing pad to avoid a decrease in polishing removal rate associated with the gum-like precipitate; and they require a post-polishing cleaning of the wafer with to avoid defect creation. These cleaning steps require strong and costly cleaning solutions and have an associated "cost of ownership"arising from the delayed wafer throughput.

    [0006] WO 2004/101221 A2 discloses a CMP composition comprising an abrasive, rheology agent, oxidizing agent and a solvent, said composition further comprising from 0.1 to 25 wt. % of a chelating agent, e.g. iminodiacetic acid, and 0.01 to 10 wt. % of a corrosion inhibitor such as benzotriazole.

    [0007] US2006/160475 A1 discloses a CMP slurry composition comprising an organic polymer abrasive and a carboxylic acid complexing agent, for example iminodiacetic acid.

    [0008] There is a need for polishing compositions that clears copper with low defectivity, low copper dishing, low erosion; and all without the precipitation of Cu-BTA precipitate. Furthermore, there is a desire for these polishing attribute in a low-scratching formulation.

    STATEMENT OF THE INVENTION



    [0009] The present invention, in its various aspects, is as set out in the accompanying claims.

    [0010] An aspect of the invention provides an aqueous composition useful for chemical mechanical polishing of a patterned semiconductor wafer containing a copper interconnect metal comprising an oxidizer, 0.2 to 1.0 weight percent benzotriazole inhibitor for the copper interconnect metal, 0.001 to 15 weight percent of a water soluble modified cellulose, non-saccaride water soluble polymer, 0 to 15 weight percent complexing agent for the copper interconnect metal, 0 to 15 weight percent phosphorus compound, 0.4 to 5 weight percent of an acid compound of a formula as follows:

    where R is hydrogen or a carbon-containing compound, the acid compound being capable of complexing copper ions, and water; and the solution having an acidic pH.

    [0011] Another aspect of the invention provides an aqueous composition useful for chemical mechanical polishing of a patterned semiconductor wafer containing a copper interconnect metal comprising 0.5 to 25 weight percent oxidizer,0.2 to 1.0 weight percent benzotriazole inhibitor for the copper interconnect metal, 0.005 to 5 weight percent of a water soluble modified cellulose, 0.005 to 5 weight percent non-saccaride water soluble polymer, 0.05 to 10 weight percent phosphorus compound, 0.01 to 15 weight percent complexing agent for the copper interconnect metal, 0 to 3 weight percent abrasive, 0.4 to 5 weight percent of an acid compound of a formula as follows:

    where R is hydrogen or a carbon-containing compound, the acid compound being capable of complexing copper ions, and water; and the solution having an acidic pH.

    [0012] Another aspect of the invention provides a method for CMP of a semiconductor wafer containing a metal comprising, a) contacting the wafer with a polishing composition, the polishing composition comprising an oxidizer, 0.2 to 1.0 weight percent benzotriazole inhibitor for the copper interconnect metal, 0.001 to 15 weight percent of a water soluble modified cellulose, non-saccaride water soluble polymer, 0 to 15 weight percent complexing agent for the copper interconnect metal, 0 to 15 weight percent phosphorus compound, 0.4 to 5 weight percent of an acid compound of a formula as follows:

    where R is hydrogen or a carbon-containing compound, the acid compound being capable of complexing copper ions, and water, and the solution having an acidic pH; and b) polishing the wafer with a polishing pad.

    DETAILED DESCRIPTION



    [0013] The composition and method provide good metal removal rates, with metal clearing, and low dishing of the metal interconnects when a semiconductor wafer is exposed to CMP and a polishing composition containing an acid compound in combination with a water soluble modified cellulose, a non-saccaride water soluble polymer, an oxidizer, an inhibitor and balance water. The addition of the acid compound provides an additional benefit of lowering the green staining that arises from Cu-BTA (Cu+1) precipitate. For purposes of this specification Cu-BTA precipitate includes non-liquids such as solids, gels and polymers and may include Cu+2 ions, spinel precipitates, spinel-like precipitates and impurities. From polishing experience, an insoluble Cu-BTA precipitate forms when the product of copper ion (+1) and BTA concentrations exceed the Ksp at its operating temperature. The precipitation of the Cu-BTA appears to occur in acidic polishing solutions following equilibrium expression (1):



    [0014] Although some amines are effective for dissolving the green "slime-like" precipitate from wafers and polishing pad, particular acid compounds can reduce or eliminate harmful quantities of the Cu-BTA precipitate. In particular, the acid compound has a formulation as follows:

    where R is hydrogen or a carbon-containing compound. These acid compounds are capable of complexing copper ions having a single valency (+1) and divalent (+2) copper ions. During polishing, the complexing agent appears to complex sufficient copper ions to reduce the formation of Cu-BTA precipitate and controls the rate of formation of Cu+2 ions in expression (2) as follows:



    [0015] The formulation has a concentration of 0.4 to 5 weight percent acid compound to control Cu-BTA precipitation. At complexing compound concentrations above about 0.4 weight percent, increasing the complexing compound concentration can increase or accelerate copper removal rate; and at complexing compound concentrations from 0 to about 0.4 weight percent, increasing the complexing compound concentration can decrease copper removal rate. In particular, at least one of iminodiacetic acid ("IDA") and ethylenediaminetetraacetic acid ("EDTA") provide an effective means for reducing Cu-BTA precipitation. IDA appears to represent the most effective complexing agent for reducing Cu-BTA precipitate.

    [0016] The composition of the present invention utilizes 0.001 to 15 weight percent water soluble cellulose modified with carboxylic acid functionality and water miscible organic solvents such as alcohols and ketones. Preferably, the composition contains 0.005 to 5 weight percent of water soluble cellulose. Most preferably, the composition contains 0.01 to 3 weight percent of water soluble cellulose. Exemplary modified cellulose are anionic gums such as at least one of agar gum, arabic gum, ghatti gum, karaya gum, guar gum, pectin, locust bean gum, tragacanth gums, tamarind gum, carrageenan gum, and xantham gum, modified starch, alginic acid, mannuronic acid, guluronic acid, and their derivatives and copolymers. The preferred water soluble cellulose, carboxy methyl cellulose (CMC), has a degree of substitution of 0.1 to 3.0 with a weight average molecular weight of 1K to 1000K. For purposes of this specification, molecular weight refers to cellulose in weight average molecular weight. More preferred, the CMC has a degree of substitution of 0.7 to 1.2 with a weight average molecular weight of 40K to 250K. Degree of substitution in CMC is the average number of acetate etherified hydroxyl groups on each anhydroglucose unit in the cellulose molecule. It can be considered as a measure of the "density" of carboxylic acid groups in the CMC.

    [0017] The non-saccaride water soluble polymers of this invention include acrylic acid polymers, methacrylic polymers and copolymers synthesized utilizing acrylic acid monomer or methacrylic acid monomer. For purposes of this specification, the non-saccaride water soluble polymers also include polymers of various molecular weights and low molecular weight oligomers. Copolymers include those formed from a combination of acrylic acid and methacrylic acid; and in particular, copolymers formed from an acrylic acid to methacrylic acid mole ratio in a range of 1:30 to 30:1; preferably in a range of 1:9 to 9:1; and most preferably about 2:3. The copolymer preferably has a weight average molecular weight in the range of 1K to 1000K; preferably in the range of 10K to 500K.

    [0018] Alternatively, the non-saccaride water soluble polymer is an amphiphilic polymer, such as a copolymer formed from acrylic acid or methacrylic acid. The amphiphilic polymers referred to in this specification are block copolymers comprised of a hydrophobic segment and a hydrophilic segment. The hydrophobic segment can be polymeric chains with a carbon number varying from 2 to 250. For purposes of this specification, carbon number represents the number of carbon atoms in the hydrophobic segment. Preferably, the carbon number is 5 to 100 and most preferably 5 to 50. The hydrophilic segment is ionic. The number of monomeric units of the hydrophilic segment preferably varies from 1 to 100. Preferably, the composition contains 0.005 to 5 weight percent non-saccaride water soluble polymers. More preferably, the composition contains 0.01 to 3 weight percent non-saccaride water soluble polymers. Most preferably, the composition contains 0.02 to 2 weight percent of non-saccaride water soluble polymers.

    [0019] The amphiphilic polymers' preferred number average molecular weight is 50 to 5,000-this specification refers to amphiphilic polymer in terms of number average molecular weight and specifically by aqueous gel permeation chromatography using TSK-GEL pn/08025 GMPWx and TSK-GEL pn/08020 G2500PWx columns in series with a refractive index detector and sodium phosphate buffer eluent. More preferably, the number average molecular weight is between 50 and 4,000 and most preferably the number average molecular weight is between 100 and 3,000. Ionic segments include cationic, anionic, and zwitterions (polyampholytes and polybetaines). Preferably, the hydrophilic segment is anionic such, as polyacrylic acid or a polymethacrylic acid. The hydrophilic segment preferably contains polyacrylic acid, polymethacrylic acid or a copolymer of acrylic acid and methacrylic acid. The combining of these segments into a copolymer produces molecules with properties different than their respective homopolymers that facilitate clearing without excessive dishing of metal interconnects. The hydrophobic end of the polymer may include hydrocarbon chains or an alkylmercaptan. Most preferably, the hydrophobic and hydrophilic segments combine in the form of a block copolymer.

    [0020] The solution contains an oxidizer. Preferably, the solution contains 0.5 to 25 weight percent oxidizer. More preferably, the oxidizer is in the range of 1 to 10 weight percent. The oxidizer is particularly effective at assisting the solution in removing copper at low pH ranges. The oxidizing agent can be at least one of a number of oxidizing compounds, such as hydrogen peroxide (H2O2), monopersulfates, iodates, magnesium perphthalate, peracetic acid and other per-acids, persulfates, bromates, periodates, nitrates, iron salts, cerium salts, Mn (III), Mn (IV) and Mn (VI) salts, silver salts, copper salts, chromium salts, cobalt salts, halogens, hypochlorites and a mixture thereof. Furthermore, it is often advantageous to use a mixture of oxidizer compounds. When the polishing slurry contains an unstable oxidizing agent such as, hydrogen peroxide, it is often most advantageous to mix the oxidizer into the composition at the point of use.

    [0021] Further, the solution contains benzotriazole, hereafter "inhibitor", to control removal of copper interconnect removal rate by static etch or other removal mechanism. Adjusting the concentration of the inhibitor adjusts the interconnect metal removal rate by protecting the metal from static etch. The solution contains 0.2 to 1.0 weight percent inhibitor. Azole inhibitors are particularly effective for copper interconnect metals such as pure copper and copper alloys. Experimental testing has indicated that increasing the inhibitor concentration can increase removal rate during polishing. But increasing azole concentration provides the disadvantage of increasing the polishing solution's propensity to precipitate the copper-BTA compound. Blends of azole inhibitors can increase or decrease copper removal rate. BTA is a particularly effective inhibitor for copper.

    [0022] In addition to the inhibitor, the composition optionally contains complexing agent for the copper interconnect metal. The complexing agent, such as 0 to 15 weight percent complexing agent, may facilitate the removal rate of the metal film, such as copper. Preferably, the composition contains 0.01 to 15 weight percent copper complexing agent. Most preferably, the composition contains 0.1 to 1 weight percent copper complexing agent. Example complexing agents include acetic acid, citric acid, ethyl acetoacetate, glycolic acid, lactic acid, malic acid, oxalic acid, salicylic acid, sodium diethyl dithiocarbamate, succinic acid, tartaric acid, thioglycolic acid, glycine, alanine, aspartic acid, ethylene diamine, trimethyl diamine, malonic acid, gluteric acid, 3-hydroxybutyric acid, propionic acid, phthalic acid, isophthalic acid, 3-hydroxy salicylic acid, 3,5-dihydroxy salicylic acid, gallic acid, gluconic acid, pyrocatechol, pyrogallol, tannic acid, including, salts and mixtures thereof. Preferably, the complexing agent is selected from the group consisting of acetic acid, citric acid, ethyl acetoacetate, glycolic acid, lactic acid, malic acid, oxalic acid and mixtures thereof. Most preferably, the copper complexing agent is malic acid. Malic acid can provide an additional benefit of improving planarization efficiency.

    [0023] The composition includes 0 to 15 weight percent phosphorus-containing compound. For purposes of this specification, a "phosphorus-containing" compound is any compound containing a phosphorus atom. A preferred phosphorus-containing compound is, for example, a phosphate, pyrophosphate, polyphosphate, phosphonate, including, their acids, salts, mixed acid salts, esters, partial esters, mixed esters, and mixtures thereof, for example, phosphoric acid. In particular, a preferred aqueous polishing composition can be formulated using, for example, the following phosphorus-containing compounds: zinc phosphate, zinc pyrophosphate, zinc polyphosphate, zinc phosphonate, ammonium phosphate, ammonium pyrophosphate, ammonium polyphosphate, ammonium phosphonate, diammonium phosphate, diammonium pyrophosphate, diammonium polyphosphate, diammonium phosphonate, guanidine phosphate, guanidine pyrophosphate, guanidine polyphosphate, guanidine phosphonate, iron phosphate, iron pyrophosphate, iron polyphosphate, iron phosphonate, cerium phosphate, cerium pyrophosphate, cerium polyphosphate, cerium phosphonate, ethylene-diamine phosphate, piperazine phosphate, piperazine pyrophosphate, piperazine phosphonate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, melamine polyphosphate, melamine phosphonate, melam phosphate, melam pyrophosphate, melam polyphosphate, melam phosphonate, melem phosphate, melem pyrophosphate, melem polyphosphate, melem phosphonate, dicyanodiamide phosphate, urea phosphate, including, their acids, salts, mixed acid salts, esters, partial esters, mixed esters, and mixtures thereof. Also, phosphine oxides, phosphine sulphides and phosphorinanes and of phosphonates, phosphites and phosphinates may be used, including, their acids, salts, mixed acid salts, esters, partial esters and mixed esters. A preferred phosphorus-containing compound is ammonium phosphate.

    [0024] Advantageously, the phosphorus-containing compound of the polishing composition of the present invention is present in an amount effective to increase polishing rates at low down force pressures. It is believed that even a trace amount of the phosphorus-containing compound in the polishing composition is effective for polishing the copper. A satisfactory polishing rate at acceptable polishing down force pressures is obtained by using the phosphorus-containing compound in an amount of about 0.05 to about 10 weight percent of the composition. A preferred range for the phosphorus-containing compound is about 0.1 to about 5 weight percent of the composition. Most preferably, the phosphorus-containing compound is about 0.3 to about 2 weight percent of the composition.

    [0025] The compounds provide efficacy over a broad pH range in solutions containing a balance of water. Advantageously, the solution has an acidic pH. This solution's useful pH range extends from at least 2 to about 7, such as a value below 7. In addition, the solution preferably relies upon a balance of deionized water to limit incidental impurities. The pH of the polishing fluid of this invention is preferably from 2 to 6, more preferably a pH of 2.5 to 5.5. The acids used to adjust the pH of the composition of this invention are, for example, nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid and the like. Exemplary bases used to adjust the pH of the composition of this invention are, for example, ammonium hydroxide and potassium hydroxide.

    [0026] Optionally, alcohols or ketones, in the presence of a modified cellulose compound, provides an acceptable metal removal rate and clearing of the copper metal with low dishing. The composition may contain a non-saccaride water soluble polymer and optionally contains a phosphorus compound. Typically, such water miscible organic solvents are alcohols or ketones, such as at least one of methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, 1,2-propanediol, glycerol, acetone, and methyl ethyl ketone. Advantageously, the composition contains 0.005 to 10 weight percent of these organic solvents-this specification refers to all compositional ranges in weight percent. Preferably, the composition contains 0.01 to 7.5 weight percent of these organic solvents. Most preferably the composition contains 0.02 to 5 weight percent of these organic solvents.

    [0027] Further, the polishing composition may optionally contain abrasive, such as, 0 to 3 weight percent abrasive to facilitate metal layer removal. Within this range, it is desirable to have the abrasive present in an amount of less than or equal to 1 weight percent. Most preferably, the polishing compositions are abrasive-free.

    [0028] The abrasive has an average particle size of less than or equal to 500 nanometers (nm) for preventing excessive metal dishing, dielectric erosion and improving planarization. For purposes of this specification, particle size refers to the average particle size of the abrasive. More preferably, it is desirable to use a colloidal abrasive having an average particle size of less than or equal to 100 nm. Further, decreased dielectric erosion and metal dishing occur with colloidal silica having an average particle size of less than or equal to 70 nm. In addition, the preferred colloidal abrasive may include additives, such as dispersants, surfactants, buffers, and biocides to improve the stability of the colloidal abrasive. One such colloidal abrasive is colloidal silica from Clariant S.A., of Puteaux, France. Also, other abrasives, including, those that are fumed, precipitated, agglomerated, etc., may be utilized.

    [0029] The polishing composition may include the abrasive for "mechanical" removal of metal interconnect layers. Example abrasives include inorganic oxides, inorganic hydroxides, inorganic hydroxide oxides, metal borides, metal carbides, metal nitrides, polymer particles and mixtures comprising at least one of the foregoing. Suitable inorganic oxides include, for example, silica (SiO2), alumina (Al2O3), zirconia (ZrO2), ceria (CeO2), manganese oxide (MnO2), titanium oxide (TiO2) or combinations comprising at least one of the foregoing oxides. Suitable inorganic hydroxide oxides include, for example, aluminum hydroxide oxide ("boehmite"). Modified forms of these inorganic oxides, such as, organic polymer-coated inorganic oxide particles and inorganic coated particles may also be utilized if desired. Suitable metal carbides, boride and nitrides include, for example, silicon carbide, silicon nitride, silicon carbonitride (SiCN), boron carbide, tungsten carbide, zirconium carbide, aluminum boride, tantalum carbide, titanium carbide, or combinations comprising at least one of the foregoing metal carbides, boride and nitrides. Diamond may also be utilized as an abrasive if desired. Alternative abrasives also include polymeric particles, coated polymeric particles, and surfactant stabilized particles. The preferred abrasive, if utilized, is silica.

    [0030] The composition of the present invention is applicable to any semiconductor wafer containing a copper interconnect metal, such as pure copper or a copper alloy. For purposes of the specification, the term dielectric refers to a semi-conducting material of dielectric constant, k, which includes low-k and ultra-low k dielectric materials. The composition and method are excellent for preventing erosion of multiple wafer constituents, for example, porous and nonporous low-k dielectrics, organic and inorganic low-k dielectrics, organic silicate glasses (OSG), fluorosilicate glass (FSG), carbon doped oxide (CDO), tetraethylorthosilicate (TEOS) and a silica derived from TEOS. The compositions of this invention may also be used for ECMP (Electrochemical Mechanical Polishing).

    Examples



    [0031] In this Example, all compositions contain, by weight percent, 0.32 carboxymethylcellulose (CMC), 0.1 acrylic acid/methacrylic acid copolymer (2:3 ratio, 23K molecular weight), and 9.00 hydrogen peroxide with a pH adjusted with nitric acid and balance distilled water.

    [0032] An Applied Materials, Inc. Mirra 200mm polishing machine equipped with an ISRM detector system using an IC1010™ polyurethane polishing pad (Rohm and Haas Electronic Materials CMP Inc.) under downforce conditions of about 1.5 psi (10.3 kPa), a polishing solution flow rate of 200 cc/min, a platen speed of 93 RPM, and a carrier speed of 87 RPM planarized Cu wafers. A Kinik diamond abrasive disk conditioned the pad. The specific polishing slurry and solutions tested in Examples 1 to 6 contain a base formulation as follows:

    0.5 wt% benzotriazole (BTA)

    0.22 wt% malic acid

    0.32 wt% carboxymethylcellulose (200K molecular weight)

    0.1 wt % acrylic acid/methacrylic acid copolymer (2:3 ratio, 23K molecular weight)

    9 wt% H2O2 (Added at polishing)

    pH 3.5 (before H2O2 addition) adjusted with nitric acid

    Balance de-ionized water

    Note: In the Examples, numerals represent examples of the inventions and letters represent comparative examples.


    Example 1



    [0033] This example screened potential copper complexing agents for use in reducing the formation of green precipitate associated with high-rate copper polishing in the presence of large amounts of BTA. This example tested the base formulation modified to include 1 weight percent phosphate and 0.5 weight percent of multiple complexing agents.
    Table 1
    SampleAdditive to Base Formulation (0.5 wt%)Cu Removal Rate (Angstroms per Minute)Stain Present (?)
    A None (control) 4472 Yes
    B Aspartic Acid 7345 Yes
    C Citric Acid 2338 No
    D Glutaric Acid 6899 Yes
    E Lactic Acid 7194 Yes
    F Maleic Acid 6612 Yes
    G Malonic Acid 8327 Yes
    H Nitrilotriacetic Acid 3196 No
    I Succinic Acid 6429 Yes
    J Tartaric Acid 8901 Yes
    1 K2EDTA 3791 No
    2 Iminodiacetic Acid 4083 No


    [0034] Citric acid, EDTA, nitrilotriacetic acid and iminodiacetic acid all eliminated staining of the polishing pad. But only iminodiacetic acid and EDTA prevented stain formation in combination with sufficient copper removal rate.

    Example 2



    [0035] This Example illustrates the impact of iminodiacetic acid on removal rate and green stain formation to the base formulation with 0.44 weight percent phosphate present.
    Table 2
    SampleConcentration of Iminodiacetic Acid (Wt %)Cu Removal Rate (Angstroms per Minute)Green Cu-BTA Stain Present (?)
    A None (control) 4472 Yes
    K 0.01 4048 Yes
    L 0.1 3178 Yes
    M 0.2 3290 Yes
    3 0.4 3219 No
    4 0.44 3412 No
    5 0.6 3615 No
    6 0.8 3848 No
    7 1.0 4124 No


    [0036] Examples K to M and 3 to 7 all complex with copper to reduce the formation of copper-BTA precipitate. Polishing solutions 3 to 7, however, provided the best combination of copper removal rate and green-stain elimination. Increasing the polishing solution flow rate or adjusting pH of the polishing solution can convert polishing solutions K to M from polishing solutions that form green precipitate to polishing solutions that do not form green copper-BTA precipitate.

    Example 3



    [0037] This example illustrates the effect of ammonium phosphate and pH on copper dishing and removal rate performance.
    Table 3
     Percent IDA (wt%)Percent Ammonium Phosphate (wt%)pHCopper Removal Rate (Å/min)Dishing 100X100 Feature (Å)Pad Stain (?)
    A 0 (control) 0.44 3.5 4664 349 Yes
    8 0.44 1.5 3.7 4345 391 No
    9 0.44 1.5 3.9 3882 383 No
    10 0.44 2 4.1 3538 324 No
    11 0.4 1.5 4.1 3330 332 Yes
    N 0.35 1.5 4.1 3282 270 Yes
    P 0.3 1.5 4.1 3094 270 Yes
    Q 0.25 1.5 4.1 2873 258 Yes


    [0038] The increased ammonium phosphate concentrations increased copper removal rate. In addition, increasing the pH decreased copper dishing, but decreased the copper removal rate.

    Example 4



    [0039] The slurry evaluated the base formulation modified to include abrasive particles and 0.44 weight percent ammonium phosphate.
    Table 4
    SampleParticle TypeParticle Amount Percent (wt%)Copper Removal Rate (Å/min)Step Remaining 100X100 Feature (Å)Pad Stain IDA%/(?)
    A None 0 5320 1247 0%/Yes
    12 50 nm SiO2 1 6357 1092 0.44%/No
    13 Sphere Al2O3 0.1 5576 1245 0.44%/No
    14 Flake Al2O3 0.1 5828 1047 0.44%/No


    [0040] This Example illustrates that the formulation is suitable for the receipt of abrasive particles. In particular, both silica and alumina particles increased copper removal rate.

    Example 5



    [0041] This example illustrates the impact of malic acid on the base formulation with and without iminodiacetic acid.
    Table 5
    SampleConcentration of Malic Acid in Weight PercentConcentration of Iminodiacetic Acid in Weight PercentCu Removal Rate (Angstroms per Minute)Stain Present (?)
    A 0.22 (control) 0 4472 Yes
    R 1 0 3594 Yes
    S 1.6 0 3880 Yes
    T 2.2 0 4132 Yes
    U 2.8 0 4335 Yes
    15 0 0.44 2782 No
    16 0.22 0.44 3412 No
    17 0 0.6 3025 No
    18 0 1 3541 No


    [0042] This example illustrates that malic acid, iminodiacetic acid and a combination of malic acid and iminodiacetic acid increase the copper removal rate. In addition, further testing illustrates that malic acid improves the polishing solution's planarization ability.

    Example 6



    [0043] The following test varied iminodiacetic acid concentration in combination with 1.5 weight percent ammonium phosphate.
    Table 6
     Percent IDAPercent Ammonium PhosphatepHCopper Removal Rate (Å/min)Dishing 100X100 Feature (Å)Pad Stain (?)
    A 0 (control) 0.44 3.5 4127 353 Yes
    19 0.5 1.5 4.1 2731 248 No
    20 0.6 1.5 4.1 3272 354 No
    21 0.7 1.5 4.1 3630 305 No
    22 0.8 1.5 4.1 3841 291 No
    23 0.9 1.5 4.1 4240 344 No
    24 1 1.5 4.1 4231 282 No


    [0044] Table 6 illustrates that the polishing solutions provide effective stain control in combination with low dishing over a broad iminodiacetic acid range at a pH of 4.1.

    Example 7



    [0045] This example illustrates further benefits that can arise from process factors.
    Table 7
    SampleConditionerPolishing PadNumber of WafersStain (?)
    25 Kinik AD3CG181060/ex situ IC1010 124 Yes*
    26 Kinik AD3CG181060/partial in situ IC1010 127 No
    26 Kinik AD3CG1 81060/ex situ IC1010 127 No
    * Reduced, occurred after several wafers
    Table 8
    SampleBTAMalic AcidCMCCopolymerIDANH4H2PO4H202pH
    25 0.50 0.22 0.32 0.10 0.44 2.00 9.00 4.10
    26 0.3 0.22 0.32 0.1 1 1.5 9 4.1


    [0046] These data illustrate that in situ conditioning can further decrease a polishing pad's ability to retain the detrimental copper-BTA precipitate. These process factors can reduce the amount of iminodiacetic acid necessary for effective control of the copper-BTA precipitate. A particular example of an effective formulation is as follows: 0.3 wt% BTA, 0.22 wt% malic acid, 0.32 wt% CMC, 0.1 wt % acrylic acid/methacrylic acid copolymer (2:3 ratio, 23K molecular weight), 1 wt% iminodiacetic acid, 1.5 wt% ammonium dihydrogen phosphate NH4H2PO4 and 9 wt% H2O2 (added immediately before polishing) at a pH of 4.1 measured before H2O2 addition.


    Claims

    1. An aqueous composition useful for chemical mechanical polishing of a patterned semiconductor wafer containing a copper interconnect metal comprising an oxidizer, 0.2 to 1.0 weight percent benzotriazole inhibitor for the copper interconnect metal, 0.001 to 15 weight percent of a water soluble modified cellulose, non-saccaride water soluble polymer, 0 to 15 weight percent complexing agent for the copper interconnect metal, 0 to 15 weight percent phosphorus compound, 0.4 to 5 weight percent of an acid compound of a formula as follows:

    where R is hydrogen or a carbon-containing compound, the acid compound being capable of complexing copper ions, and water; and the solution having an acidic pH.
     
    2. The composition of claim 1 wherein the acid compound contains at least one of ethylenediaminetetraacetic acid and iminodiacetic acid.
     
    3. The composition of claim 1 wherein the water soluble modified cellulose is modified with a carboxylic acid functionality selected from at least one of carboxy methyl cellulose, agar gum, arabic gum, ghatti gum, karaya gum, guar gum, pectin, locust bean gum, tragacanth gums, tamarind gum, carrageenan gum, and xantham gum, modified starch, alginic acid, mannuronic acid, guluronic acid, and their derivatives and copolymers.
     
    4. The composition of claim 3 wherein the water soluble modified cellulose is carboxy methyl cellulose.
     
    5. The composition of claim 1 wherein the composition is abrasive-free.
     
    6. An aqueous composition according to claim 1, comprising 0.5 to 25 weight percent oxidizer, 0.005 to 5 weight percent of a water soluble modified cellulose, 0.005 to 5 weight percent non-saccaride water soluble polymer, 0.05 to 10 weight percent phosphorus compound, 0.01 to 15 weight percent complexing agent for the copper interconnect metal and 0 to 3 weight percent abrasive
     
    7. The composition of claim 6 wherein the acid compound contains at least one of ethylenediaminetetraacetic acid and iminodiacetic acid.
     
    8. The composition of claim 6 wherein the acid compound contains at least 0.4 weight percent iminodiacetic acid.
     
    9. The composition of claim 8 wherein the composition is abrasive-free.
     
    10. A method for CMP of a semiconductor wafer containing a metal comprising, a) contacting the wafer with a polishing composition, the polishing composition comprising an oxidizer, 0.2 to 1.0 weight percent benzotriazole inhibitor for the copper interconnect metal, 0.001 to 15 weight percent of a water soluble modified cellulose, non-saccaride water soluble polymer, 0 to 15 weight percent complexing agent for the copper interconnect metal, 0 to 15 weight percent phosphorus compound, 0.4 to 5 weight percent of an acid compound of a formula as follows:

    where R is hydrogen or a carbon-containing compound, the acid compound being capable of complexing copper ions, and water, and the solution having an acidic pH; and b) polishing the wafer with a polishing pad.
     


    Ansprüche

    1. Wässrige Zusammensetzung, die für das chemisch-mechanische Polieren eines bemusterten Halbleiterwafers nützlich ist, der ein kupferzwischenverbundenes Metall enthält, das ein Oxidationsmittel, 0,2 bis 1,0 Gewichtsprozent Benzotriazolinhibitor für das kupferzwischenverbundene Metall, 0,001 bis 15 Gewichtsprozent einer wasserlöslichen modifizierten Cellulose, wasserlösliches Nichtsaccharidpolymer, 0 bis 15 Gewichtsprozent Komplexbildner für das kupferzwischenverbundene Metall, 0 bis 15 Gewichtsprozent Phosphorverbindung, 0,4 bis 5 Gewichtsprozent einer sauren Verbindung einer Formel wie folgt.

    wobei R Wasserstoff oder eine kohlenstoffhaltige Verbindung ist, wobei die saure Verbindung in der Lage ist, Kupferionen zu komplexieren, und Wasser umfasst; und die Lösung einer sauren pH-Wert aufweist.
     
    2. Zusammensetzung nach Anspruch 1, wobei die saure Verbindung mindestens eine von Ethylendiamintetraessigsäure und Iminodiessigsäure enthält.
     
    3. Zusammensetzung nach Anspruch 1, wobei die wasserlösliche modifizierte Cellulose mit einer Carbonsäurefunktionalität modifiziert ist ausgewählt unter mindestens einem von Carboxymethylcellulose, Agargummi, Gummi arabicum, Ghatt-Gummi, Karayagummi, Guargummi, Pektin, Johannisbrotkernmehl, Gummitragant, Tamarindgummi, Carrageengummi und Xanthangummi, modifizierter Stärke, Alginsäure, Mannuronsäure, Guluronsäure und ihren Derivaten und Polymeren.
     
    4. Zusammensetzung nach Anspruch 3, wobei die wasserlösliche modifizierte Cellulose Carboxymethylcellulose ist.
     
    5. Zusammensetzung nach Anspruch 1, wobei die Zusammensetzung abrasivstofffrei ist.
     
    6. Wässrige Zusammensetzung nach Anspruch 1, umfassend 0,5 bis 25 Gewichtsprozent Oxidationsmittel, 0,005 bis 5 Gewichtsprozent einer wasserlöslichen modifizierten Cellulose, 0,005 bis 5 Gewichtsprozent wasserlösliches Nichtsaccharidpolymer, 0,05 bis 10 Gewichtsprozent Phosphorverbindung, 0,01 bis 15 Gewichtsprozent Komplexbildner für das kupferzwischenverbundene Metall und 0 bis 3 Gewichtsprozent Abrasivstoff.
     
    7. Zusammensetzung nach Anspruch 6, wobei die saure Verbindung mindestens eine von Ethylendiamintetraessigsäure und Iminodiessigsäure enthält.
     
    8. Zusammensetzung nach Anspruch 6, wobei die saure Verbindung mindestens 0,4 Gewichtsprozent Iminodiessigsäure enthält.
     
    9. Zusammensetzung nach Anspruch 8, wobei die Zusammensetzung abrasivstofffrei ist.
     
    10. Verfahren für CMP eines Halbleiterwafers, der eine Metall enthält, umfassend (a Kontaktieren des Wafers mit einer Polierzusammensetzung, wobei die Polierzusammensetzung ein Oxidationsmittel, 0,2 bis 1,0 Gewichtsprozent Benzotriazolinhibitor für das kupferzwischenverbundene Metall, 0,001 bis 15 Gewichtsprozent einer wasserlöslichen modifizierten Cellulose, wasserlösliches Nichtsaccharidpolymer, 0 bis 15 Gewichtsprozent Komplexbildner für das kupferzwischenverbundene Metall, 0 bis 15 Gewichtsprozent Phosphorverbindung, 0,4 bis 5 Gewichtsprozent einer sauren Verbindung einer Formel wie folgt:

    wobei R Wasserstoff oder eine kohlenstoffhaltige Verbindung ist, wobei die saure Verbindung in der Lage ist, Kupferionen zu komplexieren, und Wasser umfasst; und die Lösung einer sauren pH-Wert aufweist und b) Polieren des Wafers mit einem Polierkissen.
     


    Revendications

    1. Composition aqueuse utile pour le polissage mécano-chimique d'une galette semi-conductrice à motif contenant un métal interconnecté de cuivre comprenant un agent oxydant, de 0,2 à 1,0 pour cent en poids d'inhibiteur benzotriazole pour le métal interconnecté de cuivre, de 0,001 à 15 pour cent en poids d'une cellulose modifiée soluble dans l'eau, d'un polymère non saccharidique soluble dans l'eau, de 0 à 15 pour cent en poids d'agent complexant pour le métal interconnecté de cuivre, de 0 à 15 pour cent en poids de composé phosphore, de 0,4 à 5 pour cent en poids d'un composé acide d'une formule telle que ci-après:

    où R est un atome d'hydrogène ou un composé contenant du carbone, le composé acide étant capable de complexer les ions cuivre, et de l'eau; et la solution ayant un pH acide.
     
    2. Composition selon la revendication 1 dans laquelle le composé acide contient au moins l'un de l'acide éthylènediaminetétraacétique et de l'acide iminodiacétique.
     
    3. Composition selon la revendication 1 dans laquelle la cellulose modifiée soluble dans l'eau est modifiée avec une fonctionnalité acide carboxylique sélectionnée parmi au moins l'un/e de la carboxy méthyl cellulose, de la gomme agar-agar, de la gomme arabique, de la gomme ghatti, de la gomme karaya, de la gomme de guar, de la pectine, de la gomme de caroube, des gommes adragantes, de la gomme de tamarin, de la gomme de carraghénane, et de la gomme de xanthane, de l'amidon modifié, de l'acide alginique, de l'acide mannuronique, de l'acide guluronique, et de leurs dérivés et copolymères.
     
    4. Composition selon la revendication 3 dans laquelle la cellulose modifiée soluble dans l'eau est la carboxy méthyl cellulose.
     
    5. Composition selon la revendication 1 dans laquelle la composition est exempte d'agent abrasif.
     
    6. Composition aqueuse selon la revendication 1, comprenant de 0,5 à 25 pour cent en poids d'agent oxydant, de 0,005 à 5 pour cent en poids d'une cellulose modifiée soluble dans l'eau, de 0,005 à 5 pour cent en poids de polymère non saccharidique soluble dans l'eau, de 0,05 à 10 pour cent en poids de composé phosphore, de 0,01 à 15 pour cent en poids d'agent complexant pour le métal interconnecté de cuivre et de 0 à 3 pour cent en poids d'agent abrasif.
     
    7. Composition selon la revendication 6 dans laquelle le composé acide contient au moins l'un de l'acide éthylènediaminetétraacétique et de l'acide iminodiacétique.
     
    8. Composition selon la revendication 6 dans laquelle le composé acide contient au moins 0,4 pour cent en poids d'acide iminodiacétique.
     
    9. Composition selon la revendication 8 dans laquelle la composition est exempte d'agent abrasif.
     
    10. Procédé de PMC d'une galette semi-conductrice contenant un métal comprenant, a) la mise en contact de la galette avec une composition de polissage, la composition de polissage comprenant un agent oxydant, de 0,2 à 1,0 pour cent en poids d'inhibiteur benzotriazole pour le métal interconnecté de cuivre, de 0,001 à 15 pour cent en poids d'une cellulose modifiée soluble dans l'eau, de polymère non saccharidique soluble dans l'eau, de 0 à 15 pour cent en poids d'agent complexant pour le métal interconnecté de cuivre, de 0 à 15 pour cent en poids de composé phosphore, de 0,4 à 5 pour cent en poids d'un composé acide d'une formule telle que ci-après:

    où R est de l'hydrogène ou un composé contenant du carbone, le composé acide étant capable de complexer les ions cuivre, et de l'eau, et la solution ayant un pH acide; et b) le polissage de la galette avec un tampon de polissage.
     




    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description