JP2006202892A - Chemical mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing method which blocks dishing and erosion of a surface to be polished, improve smoothness thereof, and suppresses the generation of scratches on wiring so as to improve the yield of manufacturing a semiconductor device. <P>SOLUTION: The chemical mechanical polishing method uses a water based dispersing element comprised of (A) abrasive grains, (B) a compound having a heterocycle, (C) a surfactant, and (D) a hydrogen peroxide, to polish an object to be polished chemically and mechanically. The electric conductivity of the water based dispersing element is 4-40 mS/cm, and the chemical mechanical polishing includes steps of: (1) polishing the object chemically and mechanically, (2) changing a specific condition and to carry out processing for one second or more in succession after the first step; and (3) rinsing the object. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chemical mechanical polishing method. More specifically, the present invention relates to a chemical mechanical polishing method that can be suitably used in a wiring formation process of a semiconductor device that requires a mixed wiring from a fine wiring of about 0.1 μm to a wide wiring of about 100 μm, such as a high-speed logic LSI.

In recent years, with the increase in the density of semiconductor devices, miniaturization of formed wirings has progressed. A technique called a damascene method has attracted attention as a technique that can achieve further miniaturization of the wiring. In this method, a desired wiring is formed by embedding a wiring material in a groove or the like formed in an insulating material and then removing excess wiring material deposited other than the groove by chemical mechanical polishing.
In the chemical mechanical polishing step, the wiring material may be excessively polished beyond the portion to be originally removed, which may result in a concave shape. Such a concave shape is called “dishing” or “erosion” and reduces the yield of semiconductor device manufacturing.
Further, when chemical mechanical polishing is performed, scratch-like surface defects called scratches may occur on the surface to be polished, which lowers the yield of semiconductor device manufacturing as with dishing and erosion.

Conventionally, various chemical mechanical polishing aqueous dispersions have been proposed in order to suppress dishing and erosion, improve smoothness, and suppress surface defects such as scratches.
For example, Patent Document 1 discloses that an aqueous dispersion composed of an abrasive, water, and an iron compound is effective in suppressing dishing. Patent Document 2 discloses that an aqueous dispersion composed of an abrasive, α-alanine, hydrogen peroxide and water is effective in suppressing dishing and erosion, and a polished surface with excellent smoothness can be obtained. Has been.
Furthermore, Patent Document 3 discloses that an aqueous dispersion to which a surfactant is added is effective in improving the smoothness of the surface to be polished.
However, in the conventionally known technique, there is a problem that even if the surface to be polished is finished with good flatness, scratches enter the wiring and the yield is greatly reduced. Therefore, there has been a demand for a method for effectively suppressing the generation of scratches on the wiring.
JP-A-10-163141 Japanese Unexamined Patent Publication No. 2000-160141 JP 10-44047 A

  The present invention solves the above problems, and the problem is to suppress the dishing and erosion of the surface to be polished, to improve the smoothness, and to suppress the generation of scratches on the wiring, thereby increasing the yield of semiconductor device manufacturing. An object of the present invention is to provide an improved chemical mechanical polishing method.

According to the present invention, the above object of the present invention is to provide a chemical mechanical polishing aqueous system comprising (A) abrasive grains, (B) a compound having a heterocyclic ring, (C) a surfactant, and (D) hydrogen peroxide. A chemical mechanical polishing method for chemically and mechanically polishing an object to be polished using a dispersion,
The electrical conductivity of the chemical mechanical polishing aqueous dispersion is 4 to 40 mS / cm,
The chemical mechanical polishing is achieved by a chemical mechanical polishing method characterized by including the following steps.
(1) A first step of chemically and mechanically polishing an object to be polished.
(2) A second step in which at least one of the following conditions is changed, and the second step is performed continuously for 1 second or more continuously with the first step.
(I) The polishing head pressing pressure is 50% or less of the pressure in the first step.
(Ii) The rotational speed of the polishing head and / or the surface plate is set to 50% or less of the rotational speed in the first step.
(Iii) The supply amount per unit time of the chemical mechanical polishing aqueous dispersion is set to 25% or less of the supply amount per unit time in the first step.
(3) A third step of rinsing the object to be polished.

  ADVANTAGE OF THE INVENTION According to this invention, the chemical mechanical polishing method which improves the yield of semiconductor device manufacture by suppressing the dishing and erosion of a to-be-polished surface, improving smoothness, suppressing the generation | occurrence | production of the scratch on wiring is provided. .

The chemical mechanical polishing aqueous dispersion used in the chemical mechanical polishing method of the present invention comprises (A) abrasive grains, (B) a compound having a heterocyclic ring, (C) a surfactant, and (D) hydrogen peroxide. And has an electric conductivity in the range of 4 to 40 mS / cm.
(A) Examples of the abrasive grains include 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, sol-gel silica, and colloidal silica. Fumed silica can be synthesized by a method in which silicon chloride or the like is reacted with oxygen and hydrogen in the gas phase. The sol-gel method can be synthesized by a sol-gel method in which silica metal alkoxysilicon is hydrolyzed and condensed. The colloidal silica can be synthesized by an inorganic colloid method using a raw material from which impurities have been removed by purification as a starting material.

Examples of the organic particles include a group consisting of polyvinyl chloride, polystyrene, styrene copolymer, polyacetal, saturated polyester, polyamide, polycarbonate, polyolefin, olefin copolymer, phenoxy resin, (meth) acrylic resin, and acrylic copolymer. The organic particle comprised from at least 1 type selected from can be mentioned. Examples of the styrene copolymer include a styrene / methacrylic acid copolymer, a styrene / divinylbenzene copolymer, and a styrene / acrylonitrile copolymer;
Examples of the polyolefin include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, and the like;
Examples of the (meth) acrylic resin include polymethyl methacrylate and polyethylene glycol diacrylate;
Examples of the acrylic copolymer include methyl methacrylate / methacrylic acid copolymer and methyl methacrylate / ethylene glycol dimethacrylate copolymer.

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, configuration, and the like are not particularly limited.
As the organic-inorganic composite particles, for example, the following configuration can be adopted.
(1) Organic-inorganic composite particles obtained by polycondensation of 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).
(2) Organic-inorganic composite particles in which organic particles and inorganic particles having zeta potentials having 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.
(3) Organic-inorganic composite particles obtained by polycondensation of a metal or silicon alkoxide compound in the presence of the composite particles of (2) above. Here, as the metal or silicon alkoxide compound, the same compounds as in the above (1) can be used.

Of these, inorganic particles and organic-inorganic composite particles are preferably used, and silica, alumina, and organic-inorganic composite particles are more preferably used.
The average dispersed particle size of the (A) abrasive grains blended in the chemical mechanical polishing aqueous dispersion used in the present invention is preferably 5 to 1,000 nm, more preferably 5 to 700 nm, and more preferably 10 to 500 nm. Is more preferable. By using abrasive grains having an average dispersed particle diameter in this range, a stable chemical mechanical polishing aqueous system that has a high polishing rate, sufficiently suppresses dishing and erosion, and does not cause sedimentation or separation of particles. It can be a dispersion. In addition, this average particle diameter can be measured by observing with a laser scattering diffractometer or a transmission electron microscope.
In addition, when impurity metals remain in the semiconductor device after chemical mechanical polishing treatment, the yield may be lowered. Therefore, the (A) abrasive grains used in the present invention have these impurity metal contents based on the total amount of abrasive grains. Preferably, it is 10 ppm or less, more preferably 5 ppm or less, still more preferably 3 ppm or less, and particularly preferably 1 ppm or less. Examples of the impurity metal include iron, nickel, and zinc.
The amount of the (A) abrasive grains blended in the chemical mechanical polishing aqueous dispersion used in the present invention is preferably 0.001 to 10% by mass, more preferably 0.01 to 7% by mass, More preferably, it is 0.1-5 mass%. By setting the blending amount in this range, it is possible to obtain a surface to be polished that exhibits a sufficient polishing rate and sufficiently suppresses dishing and erosion.

Examples of the compound (B) having a heterocycle include a compound having a condensed ring composed of at least one of a benzene ring or a naphthalene ring and at least one of a hetero five-membered ring or a hetero six-membered ring having at least one nitrogen atom. Can be mentioned. As the compound having such a structure, for example, a compound having a structure selected from quinoline, isoquinoline, benzotriazole, benzimidazole, indole, isoindole, quinazoline, cinnoline, quinoxaline, phthalazine and acridine is preferable. A compound having a triazole or benzimidazole structure is more preferred.
Specific examples of such compounds include quinaldic acid, quinolinic acid, benzotriazole, carboxybenzotriazole, and benzimidazole. Among these, quinaldic acid and quinolinic acid are preferably used.
The amount of the compound (B) having a heterocyclic ring blended in the chemical mechanical polishing aqueous dispersion used in the present invention is preferably 0.01 to 2% by mass, more preferably 0.02 to 1.5. It is mass%, More preferably, it is 0.03-1 mass%. By setting the blending amount within this range, it is possible to obtain an aqueous dispersion in which high polishing rate and scratch derivation are suppressed.

As the surfactant (C), any of cationic surfactants, anionic surfactants, amphoteric surfactants and nonionic surfactants can be used.
Examples of the cationic surfactant include alkylamine salts and quaternary ammonium salts. Examples of counter anions in these cationic surfactants include chloride ions.
Examples of the anionic surfactant include alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfate ester salts, alkylbenzene sulfonates, other sulfonates, fatty acid salts, and phosphates. Examples of alkyl sulfate salts include, for example, lauryl sulfate salts; polyoxyethylene alkyl ether sulfate ester salts, such as polyoxyethylene lauryl ether sulfate salts; alkylbenzene sulfonate salts such as, for example, dodecylbenzene sulfonate salts; Examples of the sulfonate include alkylnaphthalene sulfonate, dialkyl sulfosuccinate, alkyl diphenyl ether disulfonate, etc .; examples of the fatty acid salt include oleate, and stearate phosphate; examples of the phosphate include polyoxy Examples thereof include ethylene alkyl ether phosphates. When these anionic surfactants are salts, examples of counter cations include ammonium ions and potassium ions.

Examples of the zwitterionic surfactants include alkylamine oxide and alkylbetaine. Examples of the alkylamine oxide include lauryldimethylamine oxide and the like; examples of the alkylbetaine include laurylbetaine and stearylbetaine. , Can be mentioned respectively.
Examples of the nonionic surfactant include ether type nonionic surfactants, ester type nonionic surfactants, and other nonionic surfactants. Examples of the ether type nonionic surfactant include polyoxyalkylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; Examples of the surfactant include sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester and the like; other nonionic surfactants include, for example, poly Examples thereof include oxyethylene alkylamine, alkyl alkanolamide, acetylene diol, and the like.

Of these surfactants, anionic surfactants and nonionic surfactants are preferred, alkylbenzene sulfonates, alkyl sulfates, acetylenic diol nonionic surfactants are more preferred, dodecyl benzene sulfonates, dodecyl sulfates. Salts, acetylenic diol nonionic surfactants and the like are more preferable. Examples of commercially available acetylenic diol surfactants include Surfynol 465 and Surfynol 485 (above, manufactured by Air Products Japan Co., Ltd.).
The amount of the (C) surfactant blended in the chemical mechanical polishing aqueous dispersion used in the present invention is preferably 0.001 to 1% by mass, more preferably 0.005 to 0.7% by mass. More preferably, it is 0.01-0.5 mass%. By setting the blending amount in this range, it is possible to obtain a polished surface in which a sufficient polishing rate can be obtained and the occurrence of corrosion on the polished surface is sufficiently suppressed.

The amount of (D) hydrogen peroxide blended in the chemical mechanical polishing aqueous dispersion used in the present invention is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass. More preferably, it is 0.1 to 2% by weight. By setting the blending amount in this range, it is possible to obtain a polished surface in which a sufficient polishing rate can be obtained and the occurrence of corrosion on the polished surface is sufficiently suppressed.
The chemical mechanical polishing aqueous dispersion used in the present invention can contain (D) an oxidizing agent other than hydrogen peroxide, but preferably does not contain ammonium persulfate.

The chemical mechanical polishing aqueous dispersion used in the present invention has an electric conductivity in the range of 4 to 40 mS / cm, preferably 5 to 30 mS / cm, and more preferably 6 to 20 mS / cm.
In order to adjust the electric conductivity within the above range, various additives can be blended as necessary. As an additive which can be mix | blended in order to adjust conductivity, an organic acid, an inorganic acid, an organic base, and an inorganic base can be mentioned, for example.
Examples of the organic acid include oxalic acid, malonic acid, succinic acid, citric acid, maleic acid, formic acid, fumaric acid, gallic acid, phthalic acid, quinolinic acid, quinaldic acid, malic acid, tartaric acid, p-toluenesulfonic acid, dodecyl. Benzenesulfonic acid, isoprenesulfonic acid, gluconic acid, lactic acid, glycolic acid, polyacrylic acid and the like can be mentioned.
Examples of the inorganic acid include nitric acid, sulfuric acid, and phosphoric acid.
Examples of the organic base include amine compounds, amide compounds, and quaternary ammonium salts. Examples of the amine compound include dimethylamine, diethylamine, ethylenediamine, diethanolamine, triethanolamine, hydrazine and the like; Examples of the amide compound include amide sulfate, potassium amide and the like; Examples of the quaternary ammonium salt include tetramethylammonium hydroxide and the like. Can be mentioned respectively.
Examples of the inorganic base include alkali metal hydroxides and ammonia. Examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

The organic acid, inorganic acid, organic base, and inorganic base described above may be blended as a salt composed of the organic acid or inorganic acid and the organic base or inorganic base. Examples of such salts include ammonium sulfate, potassium oxalate, ammonium citrate, ammonium phosphate, potassium phosphate, ammonium nitrate, and potassium nitrate.
By using an aqueous dispersion for chemical mechanical polishing whose electrical conductivity is adjusted to the above range, it is possible to obtain a polished surface in which a high polishing rate can be obtained and the occurrence of corrosion of the polished surface is sufficiently suppressed. It will be possible to obtain.
It should be understood that the electric conductivity is measured at 25 ° C.
The chemical mechanical polishing aqueous dispersion used in the present invention has a pH of preferably 4 to 12, more preferably 5 to 11.

The chemical mechanical polishing method of the present invention using the chemical mechanical polishing aqueous dispersion as described above includes the following steps.
(1) A first step of chemically and mechanically polishing an object to be polished.
(2) A second step in which at least one of the following conditions is changed, and the second step is performed continuously for 1 second or more continuously with the first step.
(I) The polishing head pressing pressure is 50% or less of the pressure in the first step.
(Ii) The rotational speed of the polishing head and / or the surface plate is set to 50% or less of the rotational speed in the first step.
(Iii) The supply amount per unit time of the chemical mechanical polishing aqueous dispersion is set to 25% or less of the supply amount per unit time in the first step.
(3) A third step of rinsing the object to be polished.

The method of the present invention can be carried out using a commercially available chemical mechanical polishing apparatus.
Examples of commercially available chemical mechanical polishing apparatuses include, for example, model “EPO-112”, “EPO-222” (above, manufactured by Ebara Corporation), model “LGP-510”, “LGP-552” (above, Wrap Master SFT), trade name “Mirra” (Applied Materials) and the like.
Hereinafter, each process of the chemical mechanical polishing method of the present invention will be described.

(1) A first step of chemically and mechanically polishing an object to be polished.
The first step is a step of chemically and mechanically polishing the object to be polished.
The first step can be performed under conditions known as a chemical mechanical polishing method. The polishing conditions that can be employed in the first step should be appropriately selected according to the chemical mechanical polishing apparatus to be used.
For example, when using Mirra (Applied Materials Co., Ltd.), it can be carried out under the following conditions.
Supply amount of chemical mechanical polishing aqueous dispersion per unit time: preferably 50 to 500 mL / min, more preferably 100 to 300 mL / min Polishing head rotation speed: preferably 40 to 300 rpm, more preferably 60 to 200 rpm
Surface plate rotation speed: preferably 30 to 200 rpm, more preferably 50 to 150 rpm
Polishing head rotational speed / surface plate rotational speed ratio: preferably 0.2-5, more preferably 0.3-3
Polishing head pressing pressure: preferably 0.2-7 psi, more preferably 0.3-5 psi
The time required for the first step should be appropriately set depending on the type of chemical mechanical polishing aqueous dispersion used and the chemical mechanical polishing conditions employed.
By this first step, substantially all of the portion to be removed by the chemical mechanical polishing method of the present invention is removed from the object to be polished.

(2) A second step in which at least one of the following conditions is changed, and the second step is performed continuously for 1 second or more continuously with the first step.
(I) The polishing head pressing pressure is 50% or less of the pressure in the first step.
(Ii) The rotational speed of the polishing head and / or the surface plate is set to 50% or less of the rotational speed in the first step.
(Iii) The supply amount per unit time of the chemical mechanical polishing aqueous dispersion is set to 25% or less of the supply amount per unit time in the first step.

The first condition change in the second step is that (i) the polishing head pressing pressure is 50% or less of the pressure in the first step. When adopting the first condition change in the second step, the polishing head pressing pressure is preferably 5 to 50%, more preferably 7 to 40%, and still more preferably with respect to the pressure in the first step. Is 10-30%.
The second condition change in the second process is (ii) setting the rotation speed of the polishing head and / or the surface plate to 50% or less of the rotation speed in the first process. When changing the number of revolutions of the polishing head in the second step, the number of revolutions of the polishing head is preferably 5 to 50%, more preferably 7 to 40%, still more preferably relative to the number of revolutions of the polishing head in the first step. Is 10-30%. Moreover, when changing the rotation speed of a surface plate, the rotation speed of a surface plate becomes like this. Preferably it is 5-50% with respect to the surface plate rotation speed in a 1st process, More preferably, it is 7-40%, More preferably Is 10-30%.
Here, only the rotation speed of the polishing head may be changed, only the rotation speed of the surface plate may be changed, or both rotation speeds may be changed. It is preferable to change.
The third condition change in the second step is (iii) setting the supply amount per unit time of the chemical mechanical polishing aqueous dispersion to 30% or less of the supply amount per unit time in the first step. When the third condition change is adopted in the second step, the supply amount per unit time of the chemical mechanical polishing aqueous dispersion in the second step is preferably relative to the supply amount per unit time in the first step. It is 2-30%, More preferably, it is 5-20%, More preferably, it is 7-15%.

In the second step, only one of the above three condition changes may be made, or two or more condition changes may be made simultaneously.
Such a second step is performed for 1 second or longer, preferably 2 to 40 seconds, more preferably 3 to 20 seconds. By setting the process time within this range, the generation of scratches on the object to be polished can be efficiently suppressed, and unnecessary extension of the total process time can be avoided.

(3) Third step of rinsing the object to be polished The third step of the present invention is a step of rinsing the surface to be polished.
As the rinse liquid, for example, water or an aqueous solution or an aqueous dispersion containing an appropriate cleaning agent can be used.
Examples of the appropriate cleaning agent include citric acid, oxalic acid, polyacrylate, and the like.
The third step can be performed under appropriate conditions. For example, when a citric acid aqueous solution is used, the third step can be performed under the following conditions.
Supply amount of rinsing liquid per unit time: preferably 300 to 5000 mL / min, more preferably 400 to 4000 mL / min Polishing head rotation speed: preferably 40 to 300 rpm, more preferably 60 to 200 rpm
Surface plate rotation speed: preferably 30 to 200 rpm, more preferably 50 to 150 rpm
Polishing head rotational speed / surface plate rotational speed ratio: preferably 0.2-5, more preferably 0.3-3
Polishing head pressing pressure: preferably 0.2-7 psi, more preferably 0.3-5 psi
Time required: preferably 2 to 60 seconds, more preferably 3 to 30 seconds By the chemical mechanical polishing method of the present invention comprising the above three steps, the occurrence of dishing, erosion and scratches was suppressed at a high polishing rate. A high-quality polished surface can be obtained.

The method of the present invention exerts 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 invention, for example, a composite substrate material 1 having a structure as shown in FIG. 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 invention 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. An insulating film 22 made of silicon nitride or the like formed on 21 may be provided.

Examples of the metal that is the wiring material include tungsten, aluminum, copper, and alloys containing these. Among these, when copper or an alloy containing copper is used as the wiring material, the effect of the present invention 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 formed by a vacuum process (for example, a PETEOS film (Plasma Enhanced-TEOS film), an HDP film (High Density Plasma Enhanced-TEOS film), and a thermal chemical vapor deposition method. Silicon oxide film obtained), insulating film called FSG (Fluorine-doped silicate glass), boron phosphorus silicate film (BPSG film), insulating film called SiON (Silicon Oxide Nitride), silicon nitride, low dielectric constant insulating film, etc. Can be mentioned.

In the chemical mechanical polishing method of the present invention, the metal material to be removed of the metal film 14 other than the metal wiring portion buried in the wiring recess is chemically treated until a predetermined surface, for example, the barrier metal film 13 is exposed. By adopting when mechanical polishing is performed (see FIGS. 1B and 2B), the effect is maximized.
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 accuracy is formed (see FIGS. 1C and 2C).

Hereinafter, the present invention will be described more specifically with reference to examples.
(1) Preparation of Aqueous Dispersion Containing Colloidal Silica Particles Into a flask, 70 parts by mass of 25% by weight ammonia water, 40 parts by mass of ion-exchanged water, 175 parts by mass of ethanol and 21 parts by mass of tetraethoxysilane were added. The temperature was raised to 60 ° C. while stirring at 180 rpm, and stirring was continued for 2 hours at this temperature, followed by cooling to obtain a colloidal silica / alcohol dispersion having an average particle size of 97 nm. Next, the operation of removing the alcohol content by adding an ion-exchange water to the dispersion at a temperature of 80 ° C. by an evaporator was repeated several times, the alcohol content in the dispersion was removed, and the colloidal silica having an average dispersed particle size of 97 nm. An aqueous dispersion containing 8% by mass of was prepared.

(2) Preparation of aqueous dispersion containing fumed silica particles 2 kg of fumed silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name “Aerosil # 90”) and 14 kg of ion-exchanged water were put into a container. Was dispersed with an ultrasonic disperser and filtered with a filter having a pore diameter of 5 μm to prepare an aqueous dispersion containing 12.5% by mass of fumed silica having an average dispersed particle diameter of 180 nm.

(3) Preparation of Aqueous Dispersion Containing Alumina Particles 1 kg of fumed alumina particles (trade name “Alumina C” manufactured by Nippon Aerosil Co., Ltd.) and 9 kg of ion-exchanged water are put into a container, and this is subjected to ultrasonic waves. An aqueous dispersion containing 10% by mass of fumed silica having an average dispersed particle diameter of 510 nm was prepared by dispersing with a disperser and filtering with a filter having a pore diameter of 20 μm.

(4) Preparation of aqueous dispersion containing organic-inorganic composite particles (4-1) Preparation of aqueous dispersion (a) containing surface-treated organic particles In a flask, 90 parts by mass of methyl methacrylate, methoxy 5 parts by mass of polyethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester M-90G # 400”), 5 parts by mass of 4-vinylpyridine, azo polymerization initiator (manufactured by Wako Pure Chemical Industries, Ltd.) , Trade name “V50”) and 2 parts by mass of ion exchanged water and 400 parts by mass of ion-exchanged water were added, the temperature was raised to 70 ° C. with stirring in a nitrogen gas atmosphere, and polymerization was performed for 6 hours. As a result, an aqueous dispersion containing 19% by mass of polymethyl methacrylate-based particles having an amino group and a polyethylene glycol chain was obtained. The polymerization yield was 95%.
100 parts by mass of this aqueous dispersion was put into another flask, 1 part by mass of methyltrimethoxysilane was added, and the mixture was stirred at 40 ° C. for 2 hours. Thereafter, a 1N aqueous nitric acid solution was added to adjust the pH to 2.0, and an aqueous dispersion (a) containing 15% by mass of surface-treated organic particles (average dispersed particle diameter 150 nm) was obtained.
The zeta potential of the surface-treated organic particles contained in this aqueous dispersion (a) was +17 mV.

(4-2) Preparation of Aqueous Dispersion (b) Containing Colloidal Silica Particles 1N water is added to an aqueous dispersion containing 10% by mass of colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name “Snowtex O”). An aqueous potassium oxide solution was added to adjust the pH to 8.0 to obtain an aqueous dispersion (b) containing 10% by mass of colloidal silica particles (average dispersed particle diameter: 15 nm).
In addition, the zeta potential of the colloidal silica particles contained in the aqueous dispersion (b) was −40 mV.

(4-3) Preparation of aqueous dispersion containing organic-inorganic composite particles To 100 parts by mass of the aqueous dispersion (a) prepared in (4-1) above, the aqueous dispersion prepared in (4-2) above ( b) 50 parts by mass were gradually added and mixed over 2 hours, and further stirred for 2 hours to obtain an aqueous dispersion containing particles having silica particles attached to polymethyl methacrylate particles. Next, after adding 2 parts by mass of vinyltriethoxysilane to this aqueous dispersion and stirring for 1 hour, 1 part by mass of tetraethoxysilane was added, the temperature was raised to 60 ° C., and stirring was further continued for 3 hours. By cooling to room temperature, an aqueous dispersion containing 14% by mass of organic-inorganic composite particles (average dispersed particle size of 180 nm) was obtained. When the organic / inorganic composite particles were observed with a transmission electron microscope, the organic / inorganic composite particles had silica particles attached to about 80% of the surface of the polymethyl methacrylate-based particles.

(5) Preparation of chemical mechanical polishing aqueous dispersion (5-1) Preparation of chemical mechanical polishing aqueous dispersion S1 A polyethylene bottle contains (A) colloidal silica particles prepared in (1) as abrasive grains. The amount of the aqueous dispersion to be equivalent to 2 parts by mass in terms of dry silica, (B) 0.8 part by mass of quinaldic acid as the compound having a heterocyclic ring, and (C) 0. 0 ammonium dodecylbenzenesulfonate as the surfactant. 5 parts by mass, (D) 0.4 parts by mass of hydrogen peroxide (however, hydrogen peroxide was added in an amount of 30% by mass aqueous solution to be 0.4 parts by mass in terms of pure product) and After adding 0.4 parts by mass of ammonium sulfate, mix well, and then add a 28% by mass ammonia aqueous solution as a pH adjuster in such an amount that the pH of the final chemical mechanical aqueous dispersion should be 10.0; Furthermore, the total amount is 100 After adding ion-exchanged water to a mass% and stirring, chemical mechanical polishing aqueous dispersion S1 was prepared by filtering with a filter having a pore size of 0.5 μm.

(5-2) Preparation of Chemical Mechanical Polishing Aqueous Dispersions S2 to S8 The types and amounts of each component of the chemical mechanical aqueous dispersions were as described in Table 1, except that the above (5-1) Similarly, chemical mechanical polishing aqueous dispersions S2 to S8 were prepared.

However, in Table 1, the following abbreviations represent the following meanings. Further, “-” in the table indicates that the component corresponding to that column was not added.
(B) Compound having heterocyclic ring BTA: Benzotriazole CBT: Carboxybenzotriazole (C) Surfactant DBSA: Ammonium dodecylbenzenesulfonate ADS: Ammonium dodecylsulfate Other additive Additive A: Ammonium sulfate Additive B: Potassium oxalate Additive C: ammonium citrate

Example 1
The chemical mechanical polishing equipment manufactured by Applied Materials, model “Mirra / Mesa”, and the chemical mechanical polishing pad manufactured by Rohm and Haas Electronic Materials, model “IC1100” are used. Using “S1” prepared in (5-1) above as an aqueous dispersion for mechanical polishing, a blanket wafer having a copper layer (diameter: 200 mm, copper layer thickness: 1500 nm, manufactured by atdf) under the following conditions: Stage polished.
<First stage>
Chemical mechanical polishing aqueous dispersion supply rate: 300 mL / min Polishing head pressing pressure: 3 psi
Polishing head rotation speed: 120 rpm
Plate rotation speed: 125rpm
Polishing time: 2 minutes <second stage>
Chemical mechanical polishing aqueous dispersion supply rate: 300 mL / min Polishing head pressing pressure: 0.15 psi
Polishing head rotation speed: 120 rpm
Plate rotation speed: 125rpm
Polishing time: 10 seconds

When the removal rate and the number of scratches of the copper layer were measured for the wafer after the two-stage polishing, the removal rate of the copper layer was 980 nm / min, and the number of scratches was 48 per wafer.
The copper removal rate was determined by a four-probe method using RS75 (manufactured by KLA-Tencor).
The number of scratches was determined by SP-1 (manufactured by KLA-Tencor).

Examples 2 to 12 and Comparative Examples 1 to 5
A blanket wafer having a copper layer was subjected to two-stage polishing in the same manner as in Example 1, except that the type of chemical mechanical polishing aqueous dispersion and the conditions of the second polishing step were as shown in Table 2. In Comparative Example 1, the second stage polishing was not performed.
Table 2 shows the results of measuring the removal rate of the copper layer and the number of scratches on the polished wafers in each Example or Comparative Example.

Examples 1 to 12 are examples of the chemical mechanical polishing method of the present invention, and it was found that this method can suppress the generation of scratches on the copper surface after polishing.
In Comparative Example 1 lacking the second step, many scratches were observed on the polished copper surface.
Comparative Example 2 shows an example in which the electrical conductivity of the chemical mechanical polishing aqueous dispersion used is lower than a predetermined value. It was found that the removal rate of copper was insufficient when polished with such an aqueous dispersion. On the other hand, Comparative Example 4 shows an example in which the electrical conductivity of the chemical mechanical polishing aqueous dispersion used is higher than a predetermined value. When polished using such an aqueous dispersion, many scratches were observed on the polished copper surface.
Comparative Example 3 shows an example in which the time of the second step is shorter than a predetermined time. It was found that the scratch suppressing effect is insufficient under such polishing conditions.
Comparative Example 5 is an example in which the polishing head pressing pressure in the second step exceeds a predetermined range. Even under such polishing conditions, the effect of suppressing scratches was insufficient.

It is a cross-sectional schematic diagram which shows an example of the to-be-polished body grind | polished by the chemical mechanical polishing method of this invention. It is a cross-sectional schematic diagram which shows an example of the to-be-polished body grind | polished by the chemical mechanical polishing method of this invention.

Claims (1)

Using a chemical mechanical polishing aqueous dispersion in which (A) abrasive grains, (B) a compound having a heterocyclic ring, (C) a surfactant, and (D) hydrogen peroxide are blended, A chemical mechanical polishing method for polishing mechanically,
The electrical conductivity of the chemical mechanical polishing aqueous dispersion is 4 to 40 mS / cm,
A chemical mechanical polishing method, wherein the chemical mechanical polishing includes the following steps.
(1) A first step of chemically and mechanically polishing an object to be polished.
(2) A second step in which at least one of the following conditions is changed, and the second step is performed continuously for 1 second or more continuously with the first step.
(I) The polishing head pressing pressure is 50% or less of the pressure in the first step.
(Ii) The rotational speed of the polishing head and / or the surface plate is set to 50% or less of the rotational speed in the first step.
(Iii) The supply amount per unit time of the chemical mechanical polishing aqueous dispersion is set to 25% or less of the supply amount per unit time in the first step.
(3) A third step of rinsing the object to be polished.

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