JP4900565B2 - Chemical mechanical polishing method - Google Patents

Description

  The present invention relates to a chemical mechanical polishing method. More particularly, the present invention relates to a chemical mechanical polishing method capable of efficiently removing excess wiring material and providing a high-quality polished surface, particularly in the manufacture of a semiconductor device using copper or a copper alloy as a wiring material.

  The present invention relates to a chemical mechanical polishing method. More particularly, the present invention relates to a chemical mechanical polishing method capable of efficiently removing excess wiring material and providing a high-quality polished surface, particularly in the manufacture of a semiconductor device using copper or a copper alloy as a wiring material.

  In recent years, semiconductor devices have been demanded to have higher density, and miniaturization of formed wirings is progressing more and more. As a technique capable of achieving further miniaturization of wiring in a semiconductor device, a method called “damascene method” has attracted attention. This method forms a desired wiring by embedding a metal material to be a wiring in a groove or the like formed in an insulating material or the like, and then removing excess wiring material by chemical mechanical polishing. In this method, a high polishing rate is required from the viewpoint of increasing the efficiency of the polishing process and increasing the throughput.

  By the way, when the damascene wiring is formed, the wiring portion may be excessively polished, resulting in a concave shape. Such a concave wiring shape is called “dishing” or “erosion” and is not preferable because it reduces the yield of semiconductor device manufacturing. Further, a scratch-like surface defect called “scratch” or the like may occur during polishing, which may similarly reduce the yield of semiconductor device manufacturing.

  Furthermore, after the chemical mechanical polishing process, residual abrasive grains on the wiring and residual foreign matter on the insulating film may become a problem, or a phenomenon called “corrosion” in which the wiring portion is corroded may occur. It is also known that the yield of semiconductor device manufacturing is greatly affected.

  In order to improve the surface flatness of the surface to be polished by suppressing the dishing and erosion, and to suppress the generation of scratches and corrosion, various chemical mechanical polishing aqueous dispersions have been proposed.

  For example, JP-A-10-163141 discloses that a composition comprising an abrasive, water and an iron compound is effective in suppressing dishing. In JP-A-2000-160141, a composition comprising an abrasive, α-alanine, hydrogen peroxide and water is effective in suppressing dishing and erosion, and a polished surface having excellent smoothness can be obtained. The effect is disclosed. Furthermore, Japanese Patent Application Laid-Open No. 10-44047 describes that the addition of a surfactant to the chemical mechanical polishing aqueous dispersion has an effect on the smoothness of the polished surface.

However, in an actual chemical mechanical polishing process, a high polishing rate is required in addition to improving the surface flatness of the surface to be polished and suppressing the occurrence of surface defects, and it relates to an aqueous dispersion for chemical mechanical polishing that can achieve both of these. Little consideration has been given.
JP-A-10-163141 JP 2000-160141 A JP 10-44047 A

  INDUSTRIAL APPLICABILITY The present invention can provide a chemical mechanical polishing method that provides a high-quality polished surface with excellent surface flatness and suppressed generation of surface defects and exhibits a high polishing rate.

  The above object is achieved by the chemical mechanical polishing method according to one embodiment of the present invention.

A chemical mechanical polishing method according to one embodiment of the present invention includes:
Including chemically polishing the surface to be polished by continuously performing the first polishing step and the second polishing step having a lower polishing rate than the first polishing step,
The chemical mechanical polishing aqueous dispersion used in the first polishing step and the second polishing step is a mixture of the aqueous dispersion (I) and the aqueous solution (II),
In the first polishing step and the second polishing step, the polishing rate is changed by changing the mixing ratio of the aqueous dispersion (I) and the aqueous solution (II).

In the chemical mechanical polishing method,
The aqueous dispersion (I) contains (A) abrasive grains and (B) quinolinic acid,
The aqueous solution (II) contains (C) a polishing rate improver, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion in the second polishing step. When the supply amount of the body (I) is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), the following relationship can be satisfied.

S (I-1) / S (II-1) <S (I-2) / S (II-2)
In this case, the aqueous dispersion (I) can further contain (D) an oxidizing agent. In this case, the aqueous solution (II) can further contain (D) an oxidizing agent.

In the chemical mechanical polishing method,
The aqueous dispersion (I) contains (A) abrasive grains and (D) an oxidizing agent,
The aqueous solution (II) contains (B) quinolinic acid, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion in the second polishing step. When the supply amount of the body (I) is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), the following relationship can be satisfied.

S (I-1) / S (II-1) <S (I-2) / S (II-2)
In the chemical mechanical polishing method,
The aqueous dispersion (I) contains (A) abrasive grains and (B ′) a compound having a heterocyclic ring (excluding quinolinic acid),
The aqueous solution (II) contains (C) a polishing rate improver and (D) an oxidizing agent, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion in the second polishing step. When the supply amount of the body (I) is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), the following relationship can be satisfied.

S (I-1) / S (II-1) <S (I-2) / S (II-2)
In the chemical mechanical polishing method,
The aqueous dispersion (I) contains (A) abrasive grains, (B ′) a compound having a heterocyclic ring (excluding quinolinic acid) and (D) an oxidizing agent,
The aqueous solution (II) contains (C) a polishing rate improver, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion in the second polishing step. When the supply amount of the body (I) is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), the following relationship can be satisfied.

  S (I-1) / S (II-1) <S (I-2) / S (II-2)

  According to the chemical mechanical polishing method, a high-quality polished surface with excellent surface flatness and suppressed generation of surface defects can be obtained, and a high polishing rate can be achieved.

1. Chemical mechanical polishing method A chemical mechanical polishing method according to an embodiment of the present invention includes a first polishing step and a second polishing step having a polishing rate slower than that of the first polishing step. Including chemical mechanical polishing,
The chemical mechanical polishing aqueous dispersion used in the first polishing step and the second polishing step is a mixture of the aqueous dispersion (I) and the aqueous solution (II),
In the first polishing step and the second polishing step, the polishing rate is changed by changing the mixing ratio of the aqueous dispersion (I) and the aqueous solution (II).

  The chemical mechanical polishing method of the present embodiment exhibits its advantageous effect to the maximum when removing excess metal wiring material in the process of manufacturing a semiconductor device by the damascene method. As an object to be polished by the chemical mechanical polishing method of the present embodiment, for example, a composite substrate material 1 having a structure as shown in FIG. 1A can be cited. The composite substrate material 1 includes, for example, a substrate 11 made of silicon or the like, an insulating film 12 laminated on the surface of the substrate 11 and formed with a wiring recess such as a groove, and the surface of the insulating film 12 and a wiring recess. A barrier metal film 13 provided so as to cover the bottom and the inner wall surface of the metal, and a metal film 14 filled with the wiring recess and made of a wiring material formed on the barrier metal film 13.

  As shown in FIG. 2A, an object to be polished by the chemical mechanical polishing method of the present embodiment includes an insulating film 21 made of silicon oxide or the like between the substrate 11 and the insulating film 12, and the insulating film 21 on the insulating film 21. The insulating film 22 made of silicon nitride or the like may be formed.

  Examples of the metal that is the wiring material include tungsten, aluminum, copper, and alloys containing these. Among these, when using copper or an alloy containing copper as a wiring material, the effect of the chemical mechanical polishing method of the present embodiment is most effectively exhibited. The copper content in the alloy containing copper is preferably 95% by mass or more.

  Examples of the barrier metal include tantalum, tantalum nitride, titanium, titanium nitride, and tantalum-niobium alloy.

  Examples of the material constituting the insulating film include a silicon oxide film (for example, a PETEOS film (Plasma Enhanced-TEOS film), an HDP film (High Density Plasma Enhanced-TEOS film)) formed by a vacuum process, and a thermal chemical vapor deposition method. Obtained silicon oxide film, etc.), insulating film called FSG (Fluorine-doped silicate glass), boron phosphorus silicate film (BPSG film), insulating film called SiON (Silicon oxynitride), silicon nitride, low dielectric constant insulating film, etc. Can be mentioned.

  In the chemical mechanical polishing method of the present embodiment, the metal material to be removed of the metal film 14 other than the metal wiring portion embedded in the wiring recess is removed until a predetermined surface, for example, the barrier metal film 13 is exposed. Adopted when chemical mechanical polishing (see FIG. 1B and FIG. 2B) maximizes the effect.

  Thereafter, by a known method, chemical barrier polishing is performed so that the barrier metal film to be removed formed in the barrier metal film 13 other than the bottom and inner wall surface of the wiring recess is completely removed. A damascene wiring flattened with high precision is formed (see FIGS. 1C and 2C).

  In the chemical mechanical polishing method of the present embodiment, when removing the excess metal wiring material, a first polishing step having a high polishing rate and a second polishing step having a lower polishing rate than the first polishing step are continuously performed. To do. The time point of switching from the first step to the second step is preferably a time point when the thickness of the surplus wiring material to be removed is reduced to 0 to 700 nm from the initial thickness of the surplus wiring material. It is more preferable to be at the time point when it becomes ˜500 nm.

  By switching from the first polishing step to the second polishing step at this point, a highly flat and high-quality surface to be polished can be obtained efficiently (with a short polishing time).

  The removal rate of the excess metal wiring material in the second polishing step is preferably 90% or less, more preferably 10 to 80%, still more preferably 20 to 70 with respect to the removal rate in the first polishing step. %.

  The chemical mechanical polishing aqueous dispersion used in the chemical mechanical polishing method of the present embodiment is a mixture of the aqueous dispersion (I) and the aqueous solution (II). In the first polishing step and the second polishing step, the aqueous dispersion By changing the mixing ratio of the dispersion (I) and the aqueous solution (II), the polishing rate can be changed.

  The mixing ratio of the aqueous dispersion (I) and the aqueous solution (II) in the first polishing step and the mixing ratio of the aqueous dispersion (I) and the aqueous solution (II) in the second polishing step are the same as the aqueous dispersion (I) used. For example, the following embodiments (i) to (iv) are possible, depending on the aqueous solution (II). The following is only an example of the embodiment of the present embodiment, and the present embodiment is not limited to this.

(I) The aqueous dispersion (I) contains (A) abrasive grains and (B) quinolinic acid,
The aqueous solution (II) contains (C) a polishing rate improver, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion (I) in the second polishing step is A chemical mechanical polishing method that satisfies the following relationship when the supply amount is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2).

S (I-1) / S (II-1) <S (I-2) / S (II-2)
(Ii) The aqueous dispersion (I) contains (A) abrasive grains and (D) an oxidizing agent,
The aqueous solution (II) contains (B) quinolinic acid, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion (I) in the second polishing step is A chemical mechanical polishing method that satisfies the following relationship when the supply amount is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2).

S (I-1) / S (II-1) <S (I-2) / S (II-2)
(Iii) The aqueous dispersion (I) contains (A) abrasive grains and (B ′) a compound having a heterocyclic ring (excluding quinolinic acid),
The aqueous solution (II) contains (C) a polishing rate improver and (D) an oxidizing agent, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion (I) in the second polishing step is A chemical mechanical polishing method that satisfies the following relationship when the supply amount is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2).

S (I-1) / S (II-1) <S (I-2) / S (II-2)
(Iv) The aqueous dispersion (I) contains (A) abrasive grains, (B ′) a compound having a heterocyclic ring (excluding quinolinic acid) and (D) an oxidizing agent,
The aqueous solution (II) contains (C) a polishing rate improver, and
The supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the aqueous dispersion (I) in the second polishing step is A chemical mechanical polishing method that satisfies the following relationship when the supply amount is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2).

S (I-1) / S (II-1) <S (I-2) / S (II-2)
The (A) abrasive grains that can be contained in the aqueous dispersion (I) in the above methods (i) to (iv) are at least one selected from the group consisting of inorganic particles, organic particles, and organic-inorganic composite particles.

  Examples of the inorganic particles include silica, alumina, titania, zirconia, and ceria. Examples of the silica include fumed silica, silica synthesized by a sol-gel method, and colloidal silica. Fumed silica can be obtained by reacting silicon chloride or the like with oxygen and water in the gas phase. Silica synthesized by the sol-gel method can be obtained by hydrolysis and / or condensation reaction using an alkoxysilicon compound as a raw material. Colloidal silica can be obtained, for example, by an inorganic colloid method using a raw material purified in advance.

  Examples of the organic particles include polyvinyl chloride, styrene (co) polymer, polyacetal, polyester, polyamide, polycarbonate, olefin (co) polymer, phenoxy resin, and acrylic (co) polymer. Examples of the olefin (co) polymer include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, and the like. Examples of the acrylic (co) polymer include polymethyl methacrylate.

  The organic-inorganic composite particles need only be integrally formed to such an extent that the organic particles and the inorganic particles as described above are not easily separated during the chemical mechanical polishing step, and the type and configuration thereof are not particularly limited. .

  As organic-inorganic composite particles, for example, the following configurations (i) to (iii) can be adopted.

  (I) Organic-inorganic composite particles obtained by polycondensing a metal or silicon alkoxide compound in the presence of organic particles. Here, examples of the metal or silicon alkoxide compound include alkoxysilane, aluminum alkoxide, and titanium alkoxide. In this case, the polycondensate to be purified may be directly bonded to the functional group of the organic particles, or may be bonded via an appropriate coupling agent (for example, a silane coupling agent).

  (Ii) Organic-inorganic composite particles in which organic particles and inorganic particles having zeta potentials with different signs are combined by electrostatic force. In this case, the composite particles may be formed by mixing both in the pH range where the signs of the zeta potential of the organic particles and the inorganic particles are different, and both in the pH range where the signs of the zeta potential of the organic particles and the inorganic particles are the same. After mixing, the composite particles may be formed by changing the liquidity to a pH range where the signs of the zeta potentials of the organic particles and the inorganic particles are different.

  (Iii) Organic-inorganic composite particles obtained by polycondensing a metal or silicon alkoxide compound in the presence of the composite particles of (ii) above. Here, as the metal or silicon alkoxide compound, the same compounds as in the above (i) can be used.

  Among the above, silica or organic-inorganic composite particles are preferable as the abrasive grains (A) contained in the chemical mechanical polishing aqueous dispersion of the present embodiment.

  The (A) abrasive grains preferably have an impurity metal content of 10 ppm or less, more preferably 5 ppm or less, still more preferably 3 ppm or less, and especially 1 ppm or less with respect to the abrasive grains. Examples of the impurity metal include iron, nickel, and zinc.

  (A) The average dispersed particle diameter of the abrasive grains is preferably 5 to 1,000 nm, more preferably 7 to 700 nm, and still more preferably 10 to 500 nm. By using abrasive grains having an average dispersed particle diameter in this range, a good balance between the polished surface and the polishing rate can be achieved.

  The compound (B ′) having a heterocyclic ring that can be contained in the aqueous dispersion (I) in the above methods (iii) and (iv) is composed of a heterocyclic 5-membered ring and a heterocyclic 6-membered ring having at least one nitrogen atom. An organic compound containing at least one heterocyclic ring selected from the group consisting of Examples of the heterocyclic ring include hetero five-membered rings such as a pyrrole structure, an imidazole structure, and a triazole structure; and hetero six-membered rings such as a pyridine structure, a pyrimidine structure, a pyridazine structure, and a pyrazine structure. Such a heterocyclic ring may form a condensed ring. Specific examples include an indole structure, an isoindole structure, a benzimidazole structure, a benzotriazole structure, a quinoline structure, an isoquinoline structure, a quinazoline structure, a cinnoline structure, a phthalazine structure, a quinoxaline structure, and an acridine structure.

  Of the organic compounds having such a structure, organic compounds having a pyridine structure, a quinoline structure, a benzimidazole structure, or a benzotriazole structure are preferable. As such an organic compound, quinaldic acid, benzimidazole, and benzotriazole are preferable, and quinaldic acid is more preferable.

  However, the compound having (B ′) heterocycle does not contain quinolinic acid.

  Examples of (C) polishing rate improver that can be contained in the aqueous solution (II) in the above method (i), method (iii) and method (iv) include amino acids, aminopolycarboxylic acids, amine compounds, amino alcohols, phosphonic acids. And at least one selected from the group consisting of halide ions, thiosulfate ions, and ammonium ions.

Examples of the amino acid include glycine, alanine, glutamic acid and the like;
Examples of the aminopolycarboxylic acid include ethylenediaminetetraacetic acid and the like;
Examples of the amine compound include ethylenediamine, diethylamine, and triethylamine;
Examples of the amino alcohol include triethanolamine and the like. Of these, ammonium ions, amino acids, amine compounds, and aminopolycarboxylic acids are preferably used.

  Examples of the oxidizing agent that can be contained in the aqueous dispersion (I) in the above methods (ii) and (iv) and the aqueous solution (II) in the method (iii) include hydrogen peroxide, organic peroxides, permanganese Examples include acid compounds, dichromic acid compounds, halogen acid compounds, nitric acid compounds, perhalogen acid compounds, persulfates, and heteropoly acids.

Examples of the organic peroxide include peracetic acid, perbenzoic acid, tert-butyl hydroperoxide, and the like;
Examples of the permanganate compound include potassium permanganate and the like;
Examples of the dichromate compound include potassium dichromate;
Examples of the halogen acid compound include potassium iodate and the like;
Examples of the nitrate compound include nitric acid and iron nitrate;
Examples of the perhalogen acid compound include perchloric acid and the like;
Examples of the persulfate include ammonium persulfate and the like;
Examples of the heteropoly acid include silicomolybdic acid and silicotungstic acid.

  Among the oxidizing agents, hydrogen peroxide, organic peroxides or persulfates are preferably used from the viewpoint that the decomposition products are harmless.

  In the method (i), at least one of the aqueous dispersion (I) and the aqueous solution (II) can contain (D) an oxidizing agent.

  The aqueous dispersion (I) in the above methods (i) and (ii) can optionally contain the aqueous dispersion (I) of the methods (iii) and (iv) in addition to the above components (B ′) complex. A compound having a ring can be further contained.

  In all the above methods, the aqueous dispersion (I) and the water-soluble (II) can contain an acid, a base, a surfactant, a water-soluble polymer and the like in addition to the above-described components.

  Examples of the acid include organic acids and inorganic acids.

Examples of the organic acid include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, isoprenesulfonic acid, gluconic acid, lactic acid, citric acid, tartaric acid, malic acid, glycolic acid, malonic acid, formic acid, oxalic acid, succinic acid, and fumaric acid. , Maleic acid, phthalic acid, etc .;
Examples of the inorganic acid include nitric acid, sulfuric acid, and phosphoric acid.

  Examples of the base include organic bases and inorganic bases. Examples of the organic base include tetramethyl hydroxide. Examples of the inorganic base include alkali metal hydroxides, and specific examples thereof include sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide and the like.

  These acids and bases can also be used to adjust the pH of the aqueous dispersion (I) and the aqueous solution (II).

  Examples of the surfactant include a cationic surfactant, an anionic surfactant, and a nonionic surfactant.

  Examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts.

Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt, phosphate ester salt and the like. Examples of the carboxylate include fatty acid soaps and alkyl ether carboxylates;
Examples of the sulfonate include alkylbenzene sulfonate, alkyl naphthalene sulfonate, α-olefin sulfonate, and the like;
Examples of the sulfate ester salts include higher alcohol sulfate esters and alkyl ether sulfates;
As said phosphate ester, alkyl phosphate ester etc. can each be mentioned, for example.

  Examples of the nonionic surfactant include ether type surfactants, ether ester type surfactants, ester type surfactants, and acetylene type surfactants.

Examples of the ether type surfactant include polyoxyethylene alkyl ether and the like;
Examples of the ether ester type surfactant include polyoxyethylene ether of glycerin ester;
Examples of the ester type surfactant include polyethylene glycol fatty acid ester, glycerin ester, sorbitan ester and the like;
Examples of the acetylene surfactants include acetylene alcohol, acetylene glycol, ethylene oxide adducts of acetylene diol, and the like.

  Examples of the water-soluble polymer include polyacrylamide, polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, and hydroxyethyl cellulose.

  The content of the (A) abrasive grains contained in the aqueous dispersion (I) in the above methods (i) to (iv) is preferably 0.01 to 10% by mass with respect to the entire aqueous dispersion. Yes, more preferably 0.02 to 8% by mass, and further preferably 0.1 to 5% by mass.

  The content of (B) quinolinic acid contained in the aqueous dispersion (I) in the above method (i) is preferably 0.01 to 10% by mass, more preferably based on the whole aqueous dispersion. Is 0.02 to 5 mass%, more preferably 0.1 to 2 mass%.

  The content of quinolinic acid contained in the aqueous solution (II) in the method (ii) is preferably 0.01 to 5% by mass, more preferably 0.02 to 4% by mass with respect to the entire aqueous solution. %, More preferably 0.05 to 3% by mass.

  The content of the compound having (B ′) heterocyclic ring contained in the aqueous dispersion (I) of the above methods (iii) and (iv) is preferably 0.01 to the total amount of the aqueous dispersion. It is 10% by mass, more preferably 0.02 to 5% by mass, and further preferably 0.1 to 2% by mass.

  Further, when the aqueous dispersion (I) of the above methods (i) and (ii) contains a compound having a (B ′) heterocyclic ring, the content thereof is based on the entire aqueous dispersion. Preferably it is 0.01-10 mass%, More preferably, it is 0.02-5 mass%, Furthermore, it is preferable that it is 0.1-2 mass%.

  The content of the (C) polishing rate improver contained in the aqueous solution (II) in the above method (i), method (iii) and method (iv) is preferably 0.00 with respect to the entire aqueous dispersion. It is 01-5 mass%, More preferably, it is 0.02-4 mass%, Furthermore, it is preferable that it is 0.05-3 mass%.

  The content of the (D) oxidizing agent contained in the aqueous dispersion (I) in the above methods (ii) and (iv) is preferably 0.01 to 5% by mass with respect to the entire aqueous dispersion. More preferably, it is 0.02 to 4% by mass, and further preferably 0.05 to 1% by mass.

  The content of the (D) oxidizing agent contained in the aqueous solution (II) in the method (iii) is preferably 0.01 to 10% by mass, more preferably 0.02%, based on the entire aqueous solution. It is -8 mass%, Furthermore, it is preferable that it is 0.05-5 mass%.

  In the method (i), when the aqueous dispersion (I) contains (D) an oxidant, the content thereof is preferably 0.01 to 5 with respect to the entire aqueous dispersion. It is mass%, More preferably, it is 0.02-4 mass%, It is preferable that it is 0.05-1 mass% further.

  In the above method (i), when the aqueous system (II) contains (D) an oxidizing agent, the content thereof is preferably 0.01 to 10% by mass with respect to the entire aqueous solution, More preferably, it is 0.02-8 mass%, and it is further preferable that it is 0.05-5 mass%.

  When (D) ammonium persulfate is used as the oxidizing agent, this acts as (D) the oxidizing agent, and ammonium ions generated by ionization in an aqueous dispersion or aqueous solution can also be used as the (C) polishing rate improver. In order to work, the amount corresponding to ammonium ions in the ammonium persulfate addition amount should be calculated as (C) polishing rate improver.

  In all the above methods, when the aqueous dispersion (I) contains a surfactant, the content thereof is preferably 0.5% by mass or less with respect to the entire aqueous dispersion, and more Preferably it is 0.01-0.5 mass%.

  The pH of the aqueous dispersion (I) in all the above methods is preferably 7-12.

  The pH (II) of the aqueous solution in all the above methods is preferably 3-12.

  In the chemical mechanical polishing method of this embodiment, the supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), the supply amount of the aqueous solution (II) is S (II-1), and the second When the supply amount of the aqueous dispersion (I) in the polishing step is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), preferably S (I-1) / S ( II-1) <S (I-2) / S (II-2) is satisfied, but S (I-1) / S (II-1) in the above methods (i) to (iv) is satisfied. The value is preferably from 0.01 to 5, more preferably from 0.05 to 3. Further, the value of S (I-2) / S (II-2) in the methods (i) to (iv) is preferably 0.05 or more, more preferably 0.2 or more. In the second polishing step, the polishing step may be performed only with the aqueous dispersion (I) without supplying the aqueous solution (II).

  The chemical mechanical polishing aqueous dispersion according to the present embodiment may be prepared by supplying and supplying the aqueous dispersion (I) and the aqueous solution (II) separately, and may be integrated at the time of polishing. And the timing is not particularly limited.

  For example, the aqueous dispersion (I) and the aqueous solution (II) may be separately supplied to the polishing apparatus and mixed on a surface plate, or may be mixed in line before or in the polishing apparatus, or a mixing tank And may be mixed here. Further, a line mixer or the like may be used to make it more uniform during line mixing.

  The chemical mechanical polishing method of the present embodiment can be performed by a known method using a commercially available chemical mechanical polishing apparatus and a commercially available chemical mechanical polishing pad.

  For example, when the model “EPO112” manufactured by Ebara Corporation is used as the chemical mechanical polishing apparatus, the method of the present embodiment can be performed under the following conditions.

Chemical mechanical polishing aqueous dispersion supply rate (total amount of aqueous dispersion (I) and aqueous solution (II)): preferably 100 to 400 mL / min, more preferably 150 to 350 mL / min Platen rotation speed: preferably 30 ~ 150rpm, more preferably 50 ~ 130rpm
Polishing head rotation speed: preferably 20 to 150 rpm, more preferably 30 to 130 rpm
Polishing head pressing pressure: preferably 0.1 to 5 psi, more preferably 0.5 to 4 psi
The chemical mechanical polishing method of the present embodiment as described above is capable of obtaining a high-quality polished surface with excellent surface flatness and suppressed generation of surface defects, and exhibits a high polishing rate.

2. Examples Hereinafter, the chemical mechanical polishing method of the present invention will be described more specifically by way of examples. However, the chemical mechanical polishing method of the present invention is not limited to the following examples.

2.1. Preparation of aqueous dispersion containing abrasive grains 2.1.1. Preparation of Aqueous Dispersion Containing Fumed Silica Particles 2 kg of fumed silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name “Aerosil # 90”) are dispersed in 6.7 kg of ion exchange water using an ultrasonic disperser, and the pore size An aqueous dispersion containing 10% by mass of fumed silica having an average dispersion particle size of 220 nm was prepared by filtration through a 5 μm filter.

2.1.2. Preparation of aqueous dispersion containing colloidal silica Into a 2 L volumetric flask, 70 g of 25 mass% ammonia water, 40 g of ion exchange water, 175 g of ethanol and 21 g of tetraethoxysilane were added, and the temperature was raised to 60 ° C. while stirring at 180 rpm. Then, stirring was continued for 2 hours at this temperature, followed by cooling to obtain a colloidal silica / alcohol dispersion having an average particle diameter of 97 nm. Next, using an evaporator, the operation of removing the alcohol content was repeated several times while adding ion-exchanged water to the dispersion at a temperature of 80 ° C., the alcohol content in the dispersion was removed, and the average dispersed particle size was 97 nm. An aqueous dispersion containing 10% by mass of colloidal silica was prepared.

2.1.3. Preparation of aqueous dispersion containing organic-inorganic composite particles 2.1.3-1. Preparation of aqueous dispersion containing organic particles 90 parts by mass of methyl methacrylate, 5 parts by mass of methoxypolyethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK ester M-90G # 400”), 4- 5 parts by mass of vinylpyridine, 2 parts by mass of an azo polymerization initiator (trade name “V50”, manufactured by Wako Pure Chemical Industries, Ltd.) and 400 parts by mass of ion-exchanged water were put into a 2 L flask, and a nitrogen gas atmosphere was added. While stirring, the temperature was raised to 70 ° C. and polymerization was performed for 6 hours. As a result, an aqueous dispersion containing polymethylmethacrylate particles having an amino group cation and a functional group having a polyethylene glycol chain and having an average dispersion particle diameter of 150 nm was obtained. The polymerization yield was 95%.

2.1.3-2. Preparation of aqueous dispersion containing composite particles 2.1.3-1. 100 parts by mass of an aqueous dispersion containing 10% by mass of polymethyl methacrylate-based particles obtained in the above was put into a 2 L flask, 1 part by mass of methyltrimethoxysilane was added, and the mixture was stirred at 40 ° C. for 2 hours. Thereafter, the pH was adjusted to 2 with nitric acid to obtain an aqueous dispersion (a). The zeta potential of the polymethyl methacrylate particles contained in the aqueous dispersion (a) was +17 mV.

  On the other hand, the pH of an aqueous dispersion containing 10% by mass of colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name “Snowtex O”) was adjusted to 8 with potassium hydroxide to obtain an aqueous dispersion (b). The zeta potential of the silica particles contained in the aqueous dispersion (b) was −40 mV.

  Particles in which silica particles are adhered to polymethyl methacrylate particles after gradually adding and mixing 50 parts by mass of water dispersion (b) to 100 parts by mass of the aqueous dispersion (a) and mixing for 2 hours. An aqueous dispersion containing was obtained. Next, after adding 2 parts by weight of vinyltriethoxysilane to this aqueous dispersion and stirring for 1 hour, 1 part by weight of tetraethoxysilane was added, the temperature was raised to 60 ° C., and stirring was continued for 3 hours. By cooling, an aqueous dispersion containing organic-inorganic composite particles was obtained. The average dispersed particle size of the organic-inorganic composite particles was 180 nm, and silica particles were attached to 80% of the surface of the polymethyl methacrylate particles.

2.2. Comparative Example 1
2.2.1. Preparation of aqueous dispersion (I) In a polyethylene container, the above 2.1.1. The aqueous dispersion containing the fumed silica particles prepared in Step 1 was added in an amount corresponding to 2% by mass of the fumed silica based on the entire chemical mechanical polishing aqueous dispersion, and then 0.5% by mass of quinaldic acid. A considerable amount was added and sufficiently stirred. Then, while continuing stirring, after adding 0.1% by weight of potassium dodecylbenzenesulfonate and ammonium hydroxide as a pH adjuster, diluting with ion-exchanged water, pH 10.0 chemical mechanical polishing water system Dispersion (I) was obtained.

2.2.2. Preparation of aqueous solution (II) In a polyethylene container, quinolinic acid was added in an amount corresponding to 0.5% by mass with respect to the entire aqueous solution, and then potassium hydroxide was added as a solid as a pH adjuster. Ion exchange water was added, and 30 mass% hydrogen peroxide water was added in an amount that hydrogen peroxide should be 0.2 mass% with respect to the entire aqueous solution to obtain an aqueous solution (II) having a pH of 9.1.

2.2.3. Polishing blanket wafer with copper layer (Evaluation of polishing rate of copper film)
A copper layer using a model “EPO112” manufactured by Ebara Manufacturing Co., Ltd. as a chemical mechanical polishing apparatus and a model “IC1000-050- (603)-(P) -S400J” manufactured by Nita Haas Incorporated as a polishing pad, respectively. Using a water-based dispersion (I) and an aqueous solution (II) synthesized above, chemical blanketing was performed under the following two different conditions, respectively: . The aqueous dispersion (I) and the aqueous solution (II) were separately supplied and contacted and mixed on a surface plate.

2.2.3-1. Condition 1
Aqueous dispersion (I) supply rate: 50 mL / min Aqueous solution (II) supply rate: 250 mL / min Platen rotation speed: 100 rpm
Head rotation speed: 80 rpm
Head load: 140 g / cm ²
Polishing time: 60 seconds

2.2.3-2. Condition 2
Aqueous dispersion (I) supply rate: 150 mL / min Aqueous solution (II) supply rate: 150 mL / min The platen rotation speed, head rotation speed, head load, and polishing time are the same as in Condition 1 above.

For each of the objects treated above, the removal rate of the copper film was calculated by dividing the difference in thickness of the copper film before and after the treatment by the treatment time of the first treatment step. It was 12,000 分 / min, and 6,000 Å / min for those polished under condition 2. The thickness of the copper film was determined by measuring the sheet resistance value by a direct current 4-needle method using a resistivity meter (manufactured by NP Corp., model “Σ-5”), and this value and the theoretical resistance of copper. From the rate, it was calculated by the following formula.
Copper film thickness (Å) = sheet resistance value (Ω / cm ² ) ÷ theoretical copper resistivity (Ω / cm) × 10 ⁻⁸

2.2.4. Removal of excess copper film from patterned wafer Using a chemical mechanical polishing apparatus and polishing pad of the same type as the above "polishing a blanket wafer having a copper layer", a patterned wafer (manufactured by International Sematech, model "SEMATECH # 854", various The copper wafer has a thickness of 11,000 mm.) And the aqueous dispersion (I) and the aqueous solution (II) synthesized above are used. After performing chemical mechanical polishing (first polishing step) under the same condition as condition 1 in the above-mentioned “polishing of a blanket wafer having a copper layer”, the above condition 2 is then subjected to chemical mechanical polishing (second polishing). Polishing step) was performed. However, the polishing time of the first polishing process is 45 seconds, and the subsequent second polishing process is performed after reaching the polishing end point detected by reading the torque change from the platen current of the chemical mechanical polishing apparatus. Further, overpolishing was continued for 30 seconds.

  In addition, from the removal rate of the copper film, the polishing time of the first polishing step, and the initial deposition thickness of copper of the object to be polished, calculated in the polishing experiment under the condition 1 of the above “polishing of blanket wafer having a copper layer” The remaining thickness of the copper film after the first polishing step was calculated to be 2,000 mm. However, the removal rate of the copper film of the wafer without pattern and the removal rate of the copper film of the wafer with pattern performed under the same conditions are not exactly the same.

  The object to be polished after the above-mentioned two-step polishing was measured with a precision step gauge (manufactured by KLA Tencor, model “HRP”), and the dishing of the portion with a wiring width of 100 μm was measured and was good at 600 mm. Similarly, when the erosion of a portion where a pattern having a wiring width of 9 μm / space width of 1 μm was continued 1250 μm in a direction perpendicular to the wiring was measured, it was as good as 400 mm.

  Moreover, although copper wiring was observed with the scanning electron microscope, the corrosion (corrosion) was not seen.

2.3. Examples 1 to 4
The aqueous dispersion (I) and the aqueous solution (II) were prepared in the same manner as in Comparative Example 1 except that the types and amounts of the components of the aqueous dispersion (I) and the aqueous solution (II) were as shown in Table 1. Prepared.

Using this aqueous dispersion (I) and aqueous solution (II), aqueous dispersion (I) and aqueous solution (
The blanket wafer having the copper layer was polished and the excess copper film of the patterned wafer was removed in the same manner as in Comparative Example 1 except that the supply rate of II) was as shown in Table 2. The results are shown in Table 2. In addition, Example 2 shows that the first polishing step was performed until the polishing end point detected from the torque change of the polishing apparatus, and then polishing for 30 seconds was performed as the second polishing step.

In Examples 1 to 3 , ammonia was used as a pH adjuster, and ammonia was added as 30% by mass ammonia water. In Example 4, by using potassium hydroxide as a pH adjusting agent, potassium hydroxide was added in a solid-like.

  In Table 1, the abbreviations in the column of surfactant represent the following.

DBS-K: Potassium dodecylbenzenesulfonate DBS-A: Ammonium dodecylbenzenesulfonate SLA: Ammonium lauryl sulfate “-” in Table 1 indicates that a component corresponding to that column was not added.

2.4. Comparative Example 2
In “removal of excess copper film on patterned wafer” in Comparative Example 1, chemical mechanical polishing was started from the beginning under the conditions of the second polishing step without performing the first polishing step, and was detected from a change in torque of the polishing apparatus. After reaching the polishing end point, overpolishing was further performed for 30 seconds.

The dishing and erosion values measured in the same manner as in Comparative Example 1 were 600 mm and 400 mm, respectively, and no corrosion of the copper wiring portion was observed by scanning electron microscope observation, which was equivalent to Comparative Example 1. However, since the polishing time from the start of polishing to the end point was 115 seconds and the total polishing time was 145 seconds, it was found that the polishing time was longer than the method of Comparative Example 1.

2.5. Comparative Example 3
In “removal of excess copper film on patterned wafer” in Example 1 , chemical mechanical polishing is started under the conditions of the first polishing step, and polishing is detected from torque change of the polishing apparatus without changing conditions in the middle. After reaching the end point, polishing was continued for another 30 seconds.

When the dishing and erosion values were measured in the same manner as in Comparative Example 1, they were inferior to 1,200 and 700 mm, respectively. Further, when observed with a scanning electron microscope, corrosion was observed in the copper wiring portion.

  Although the embodiments of the present invention have already been described in detail, it will be apparent to those skilled in the art that many modifications can be made to the above-described embodiments without substantially departing from the novel matters and effects of the present invention. That would be true. Therefore, all such modifications are included in the scope of the present invention.

Fig.1 (a)-FIG.1 (c) are sectional drawings which show typically the chemical mechanical polishing method of one Embodiment of this invention. FIG. 2A to FIG. 2C are cross-sectional views schematically showing the chemical mechanical polishing method of one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Composite substrate material 11 Substrate 12 Insulating film 13 Barrier metal film 14 Metal film 21 Insulating film 22 Insulating film

Claims (6)

Including chemically polishing the surface to be polished by continuously performing the first polishing step and the second polishing step having a lower polishing rate than the first polishing step,
The chemical mechanical polishing aqueous dispersion used in the first polishing step and the second polishing step includes: (A) an aqueous dispersion (I) containing abrasive grains and (B) quinolinic acid, and (C) a polishing rate. aqueous solution containing the enhancer and (II), a mixture of,
In the first polishing step and the second polishing step, the supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), and the supply amount of the aqueous solution (II) is S (II). -1), when the supply amount of the aqueous dispersion (I) in the second polishing step is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), A chemical mechanical polishing method that changes the polishing rate by satisfying the above relationship .
S (I-1) / S (II-1) <S (I-2) / S (II-2) In claim 1,
The chemical mechanical polishing method, wherein the aqueous dispersion (I) further contains (D) an oxidizing agent. In claim 1,
The chemical mechanical polishing method, wherein the aqueous solution (II) further comprises (D) an oxidizing agent. Including chemically polishing the surface to be polished by continuously performing the first polishing step and the second polishing step having a lower polishing rate than the first polishing step,
The chemical mechanical polishing aqueous dispersion used in the first polishing step and the second polishing step includes (A) an aqueous dispersion (I) containing abrasive grains and (D) an oxidizing agent, and (B) quinolinic acid. And an aqueous solution (II) containing
In the first polishing step and the second polishing step, the supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), and the supply amount of the aqueous solution (II) is S (II). -1), when the supply amount of the aqueous dispersion (I) in the second polishing step is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), A chemical mechanical polishing method that changes the polishing rate by satisfying the above relationship.
S (I-1) / S (II-1) <S (I-2) / S (II-2) Including chemically polishing the surface to be polished by continuously performing the first polishing step and the second polishing step having a lower polishing rate than the first polishing step,
The chemical mechanical polishing aqueous dispersion used in the first polishing step and the second polishing step contains (A) abrasive grains and (B ′) a compound having a heterocyclic ring (excluding quinolinic acid). A mixture of an aqueous dispersion (I) and an aqueous solution (II) containing (C) a polishing rate improver and (D) an oxidizing agent;
In the first polishing step and the second polishing step, the supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), and the supply amount of the aqueous solution (II) is S (II). -1), when the supply amount of the aqueous dispersion (I) in the second polishing step is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), A chemical mechanical polishing method that changes the polishing rate by satisfying the above relationship.
S (I-1) / S (II-1) <S (I-2) / S (II-2) Including chemically polishing the surface to be polished by continuously performing the first polishing step and the second polishing step having a lower polishing rate than the first polishing step,
The chemical mechanical polishing aqueous dispersion used in the first polishing step and the second polishing step is (A) abrasive grains, (B ′) a compound having a heterocyclic ring (excluding quinolinic acid) and (D A mixture of an aqueous dispersion (I) containing an oxidizing agent and an aqueous solution (II) containing (C) a polishing rate improver;
In the first polishing step and the second polishing step, the supply amount of the aqueous dispersion (I) in the first polishing step is S (I-1), and the supply amount of the aqueous solution (II) is S (II). -1), when the supply amount of the aqueous dispersion (I) in the second polishing step is S (I-2) and the supply amount of the aqueous solution (II) is S (II-2), A chemical mechanical polishing method that changes the polishing rate by satisfying the above relationship.
S (I-1) / S (II-1) <S (I-2) / S (II-2)

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