JP5326492B2 - Polishing liquid for CMP, polishing method for substrate, and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP polishing solution with sufficiently fast polishing speed on a silicon oxide film, capable of stably polishing the film at high polishing speed with variations control, and to provide a method of polishing a substrate and electronic components. <P>SOLUTION: The CMP polishing solution contains a conductivity adjusting agent, an inorganic abrasive, and a dispersant; and has conductivity of 8 mS/m to 1,000 mS/m, and pH of 3.0 to 7.0. The polishing method includes a step of compressively applying a substrate on which a polished film is formed, onto a polishing cloth of a polishing fixed platen; and polishing a substrate by moving the substrate relatively to the polishing fixed platen for polishing the substrate, while feeding the CMP polishing solution between the polished substrate and the polishing cloth. The polished substrate polished by the method is used for the electronic components. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a CMP polishing liquid, a substrate polishing method, and an electronic component using the polished substrate, and more particularly to a CMP polishing liquid suitable for a semiconductor insulating film.

  In the field of semiconductor manufacturing, along with higher performance of VLSI devices, it has become the limit to achieve both high integration and high speed with conventional miniaturization technology. Therefore, while miniaturization of semiconductor elements is being promoted, on the other hand, development of technology for high integration in the vertical direction (multilayering of wiring) is being promoted.

  One of the most important technologies in multilayer wiring is CMP (Chemical Mechanical Polishing) technology. In multilayer wiring, it is essential to flatten devices one by one in order to ensure the depth of focus of lithography. This is because if there are irregularities, focusing in the exposure process becomes difficult, and formation of a fine wiring structure becomes difficult.

Such a CMP process is performed by forming a silicon oxide film such as a plasma oxide film (BPSG / HDP-SiO ₂ / p-TEOS) / interlayer insulating film embedded in the element isolation structure after forming the element isolation structure, It is also applied to Al / Cu plug planarization after wiring embedding, and is now an indispensable technology for semiconductor manufacturing.

  Here, referring to FIG. 1, a polishing process in semiconductor shallow trench isolation (STI) will be described. Shallow trench isolation is one of element isolation methods, in which a groove having a predetermined depth is formed on a substrate and then the groove is backfilled with an insulator such as a silicon oxide film to form an element isolation region. It is. Shallow trench isolation is useful because a technology with a narrow element isolation width is required as processing dimensions become finer. FIG. 1 is a schematic cross-sectional view schematically showing a substrate in a semiconductor shallow trench isolation process, where (a) is a substrate before polishing, (b) is a substrate in the middle of polishing, and (c) is a substrate after polishing. Respectively.

  When a silicon oxide film is embedded in the element isolation structure, irregularities are formed as shown in FIG. When CMP is performed, the convex portions are removed preferentially, and the concave portions are slowly removed to achieve flattening. More specifically, CMP is used to remove the excess silicon oxide film 3 formed on the silicon substrate 1, and a stopper film 2 having a low polishing rate is provided below the silicon oxide film 3 in order to stop polishing. Is formed. Silicon nitride or the like is used for the stopper film. It is desirable that the polishing rate ratio between the silicon oxide film 3 and the stopper film 2 is large.

  When flattening the unevenness in the CMP process, a two-stage polishing process may be employed. That is, as the first stage polishing, the convex portions are roughened with a polishing liquid having a high polishing rate of the silicon oxide film, and as the second stage polishing, the flatness is high, and small irregularities are completely removed with a polishing liquid having a high selection ratio. Flatten.

  As a CMP polishing liquid for removing a silicon oxide film, a polishing liquid for CMP using various inorganic abrasive grains is used. When a two-step polishing process is employed as described above, generally, The polishing liquid at the stage uses silica as abrasive grains. Although such a polishing liquid has an excellent polishing rate for silicon dioxide, it also has a problem that polishing scratches are likely to occur. In recent years, when the wiring interval becomes narrower (for example, 65 nm or less), the problem of polishing scratches has become more prominent.

On the other hand, there is a cerium oxide (ceria) polishing liquid using cerium oxide as abrasive grains (see, for example, Patent Documents 1 and 2). Examples of the abrasive dispersing agent include various water-soluble organic polymers, various monomers, inorganic bases, and the like. Among them, ceria slurry using an acrylic acid polymer based compound as a water-soluble organic polymer exhibits polishing properties excellent in flatness and selectivity of a silicon oxide film / silicon nitride film. Further, by adjusting the type and particle size of cerium oxide, it is possible to reduce polishing scratches compared to silica abrasive grains.
Japanese Patent Laid-Open No. 10-106994 Japanese Patent No. 3649279

  Recently, a polishing liquid having a higher polishing rate is required to improve the throughput of device production. However, in general, when a cerium oxide slurry using a water-soluble organic polymer as a dispersant is applied to polishing a semiconductor device having large irregularities, the polishing rate may not be sufficient. In particular, when a polymer such as a water-soluble organic polymer, a water-soluble anionic surfactant, a water-soluble nonionic surfactant, or a water-soluble zwitterionic surfactant is used as a dispersant, the flatness is excellent. However, the polishing rate may be inferior to that obtained when a monomeric dispersant is used.

  The present invention has been made in view of such circumstances, and in the CMP technique for flattening the interlayer insulating film, the BPSG film, the shallow trench isolation insulating film, and the insulating film layer between the wirings, the oxidation to be removed. A CMP polishing liquid capable of polishing a silicon film (film having silicon oxide) faster than a conventional polishing liquid, a substrate polishing method using the CMP polishing liquid, and a substrate obtained by the polishing method are provided. The purpose is to provide electronic components.

In order to solve the above problems, the present invention provides the following (1) to (18).
(1) Conductivity adjusting agent, an inorganic abrasive and CMP polishing liquid ing by blending a dispersing agent, the conductivity is 8mS / m~1000mS / m, pH is 3.0 to 7.0 der is, include dispersing agents, at least one member selected from the group consisting of water-soluble organic polymer and a water-soluble anionic surfactant is a water-soluble anionic polymeric compound, an inorganic abrasive, CMP A polishing slurry for CMP having a zeta potential of −35 mV or more and less than 0 mV in the polishing slurry.
(2) The polishing slurry for CMP according to (1), wherein the blending amount of the conductivity adjusting agent is 0.00001 mol / L to 0.01 mol / L.
(3) In (1) or (2), the conductivity modifier is a compound that provides one or more selected from inorganic cations, inorganic anions, organic cations and organic anions, and salts thereof. The polishing liquid for CMP as described.
(4) Conductivity adjusting agent is arylamine, amino alcohol, alcohol, aldehyde, ketone, quinone, aliphatic amine, nitro compound, heterocyclic amine, aminocarboxylic acid, saturated carboxylic acid, cyclic monocarboxylic acid, unsaturated mono CMP according to any one of (1) to (3), which is one or more selected from carboxylic acids, phenols, sulfonamides, thiols, ethers, sulfonic acids and halogenated organic compounds and salts thereof Polishing fluid.
(5) Conductivity adjuster is amino group, tertiary amino group, secondary amino group, carboxylic acid, hydroxyl group, amide, aldehyde group, ketone, sulfonamide, thiol, nitro group, halogen compound, sulfonic acid, cyano Polishing liquid for CMP in any one of (1)-(4) which is a compound which gives the organic cation and organic anion which have 1 type, or 2 or more types of functional groups selected from group and oxime.
(6) One or two inorganic abrasives selected from cerium-based abrasive grains, alumina, silica, titania, zirconia, magnesia, mullite, silicon nitride, α-sialon, aluminum nitride, titanium nitride, silicon carbide and boron carbide The polishing slurry for CMP according to any one of (1) to (5), which is a seed or more.
(7) The inorganic abrasive is selected from the group of cerium oxide, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, cerium carbonate The polishing slurry for CMP according to any one of (1) to (6), which is at least one kind of cerium-based abrasive.
(8) The polishing slurry for CMP according to any one of (1) to (7), wherein the inorganic abrasive is abrasive grains of cerium oxide.
(9) The polishing slurry for CMP according to any one of (1) to (8), wherein the inorganic abrasive is cerium-based abrasive grains having an average particle diameter of 0.01 μm to 1.0 μm .
(10) The polishing slurry for CMP according to any one of (1) to (9), wherein the blending amount of the inorganic abrasive is 0.05 wt% to 10.00 wt% .
(11) CMP polishing slurry according to any of the dispersant further comprises at least one member selected from water-soluble nonionic surfactant and a water-soluble zwitterionic surfactant (1) to (10) .
( 12 ) A polymer of a carboxylic acid monomer having an unsaturated double bond as a dispersant, a polymer of a monomer having an unsaturated double bond other than a carboxylic acid monomer having an unsaturated double bond, and comprises one or more of the water-soluble organic polymer is selected from copolymers of monomers having an unsaturated double bond other than the carboxylic acid monomer with a carboxylic acid monomer ( Polishing liquid for CMP in any one of 1)-( 11 ).
(13) At least one carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, alkylacrylic acid, maleic acid, fumaric acid and itaconic acid as the water-soluble organic polymer which is a water-soluble anionic polymer compound A monomer polymer, a polymer of at least one compound selected from the group consisting of acrylamide, acrylamide sulfonic acid, styrene sulfonic acid, and vinyl alcohol, and a monomer other than carboxylic acid monomer and carboxylic acid monomer. The polishing slurry for CMP according to any one of (1) to (12), comprising at least one selected from the group consisting of a copolymer with a monomer having a saturated double bond.
(14) As a water-soluble anionic surfactant, lauryl sulfate triethanolamine, lauryl ammonium sulfate, polyoxyethylene alkyl ether sulfate triethanolamine, alpha sulfo fatty acid ester salt, alkylbenzene sulfonate, alkyl sulfate, alkyl ether sulfate Any one of (1) to (13) including at least one selected from the group consisting of an ester salt, an alkylsulfuric acid triethanolamine, a phosphate ester salt, a polymerized polymer sulfate and a polymerized polymer carboxylate Polishing liquid for CMP as described in 2. above.
(15) The polishing slurry for CMP according to any one of (1) to (13), wherein the dispersant contains an acrylic acid polymer.
(16) The polishing slurry for CMP according to any one of (1) to (15) is polished with the polishing film in a state where the polishing film of the substrate having the polishing film is pressed against the polishing cloth of the polishing surface plate. A method for polishing a substrate, wherein a film to be polished is polished by relatively moving the substrate and a polishing surface plate while supplying the cloth to a cloth.
(17) The method for polishing a substrate according to (16), wherein the substrate has a step on the surface of the film to be polished, and the step is flattened by polishing the film to be polished.
(18) An electronic component comprising a substrate polished by the polishing method according to (16) or (17).

  According to the present invention, a silicon oxide film (a film having silicon oxide) to be removed is conventionally used in CMP technology for flattening an interlayer insulating film, a BPSG film, a shallow trench isolation insulating film, and an insulating film layer between wirings. A polishing liquid for CMP capable of polishing faster than the polishing liquid, a method for polishing a substrate using the polishing liquid for CMP, and an electronic component including the substrate obtained by the polishing method are provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The polishing slurry for CMP of the present invention comprises a conductivity adjusting agent, an inorganic polishing agent, and a dispersing agent, and has a conductivity of 8 mS / m to 1000 mS / m and a pH of 3.0 to 7.0. It is. Hereinafter, each component contained in the polishing slurry for CMP will be described in detail.

(Inorganic abrasive)
The inorganic abrasive used in the polishing slurry for CMP of the present invention is not particularly limited as long as it can polish a film to be polished. Specifically, for example, cerium-based abrasive grains, alumina, silica, titania, zirconia, magnesia are used. , Mullite, silicon nitride, α-sialon, aluminum nitride, titanium nitride, silicon carbide, boron carbide, and at least one compound.

  Among these, cerium-based abrasive grains are preferable in terms of high polishing speed, and cerium oxide, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, bromide are also preferable in that there are few polishing flaws. At least one selected from cerium, cerium chloride, cerium oxalate, cerium nitrate and cerium carbonate is more preferable, and cerium oxide is particularly preferable. Hereinafter, the embodiment in the case of using cerium oxide as an inorganic abrasive will be described in more detail.

(Cerium oxide)
When used for polishing a silicon oxide film formed by a TEOS-CVD method or the like, the cerium oxide as the inorganic abrasive can be polished at a higher speed as the crystallite diameter of the particle is larger and the crystal distortion is smaller. In other words, the better the crystallinity of the cerium oxide particles, the faster the polishing is possible. However, if cerium oxide having good crystallinity is used at the same time, the polishing film tends to be easily damaged. Therefore, when using the cerium oxide particles, it is preferable to use the cerium oxide particles in consideration of the crystallite diameter, crystal distortion, and the like according to the application. From such a viewpoint, it is preferable to use cerium oxide particles composed of two or more crystallites and having a crystal grain boundary as cerium oxide. Doing polishing with an abrasive comprising cerium oxide particles having crystal grain boundaries, the particles are broken by stress at the time of polishing, is estimated to generate an active surface of the cerium oxide, the surface to be polished such as SiO ₂ insulating film It is thought that it contributes to high-speed polishing without scratches. A method for obtaining such particles is disclosed in, for example, republished patent WO99 / 31195.

(Crystallite diameter / primary particle diameter)
In the polishing liquid of the present invention, when cerium oxide particles having crystal grain boundaries are used, the crystallite diameter of cerium oxide is preferably 1 nm to 400 nm. If the size of the crystallite is in the above range, the production method is not particularly limited. Moreover, when using the cerium oxide particle which does not have a crystal grain boundary, it is preferable that the primary particle diameter is 1 nm-400 nm. The crystallite diameter or primary particle diameter can be measured by a TEM photograph image or SEM image, and means an average value measured for a plurality (for example, 100) of cerium oxide particles. The same applies when abrasive grains other than cerium oxide are used.

  In addition, when used for polishing related to the manufacture of semiconductor elements, the content ratio of alkali metals and halogens in the cerium oxide particles should be suppressed to 10 ppm or less by mass ratio in order to avoid a decrease in the yield of semiconductor devices due to contamination. preferable.

  In the present invention, as a method for producing cerium oxide particles, for example, a method of firing a raw material such as cerium hydroxide or an oxidation method using hydrogen peroxide or the like can be used. In the case of firing, the firing temperature is preferably 350 ° C to 900 ° C.

  When the cerium oxide particles produced by the above method are aggregated, it is preferably mechanically pulverized. Examples of the pulverization method include dry pulverization using a jet mill or the like, and wet pulverization using a planetary bead mill or the like. The jet mill is described, for example, in Chemical Industrial Papers, Vol. 6, No. 5, (1980), pages 527-532.

  Such cerium oxide particles are dispersed in water as a main dispersion medium to obtain a cerium oxide slurry. As a dispersion method, for example, a homogenizer, an ultrasonic disperser, a wet ball mill or the like can be used in addition to a dispersion treatment with a normal stirrer.

  As a method for further micronizing the cerium oxide dispersed by the above method, for example, a sedimentation classification method is used in which the cerium oxide slurry is forcibly settled after centrifuging with a small centrifuge and only the supernatant liquid is taken out. Can do. In addition, a high-pressure homogenizer that collides the cerium oxide particles in the dispersion medium with each other at high pressure may be used.

  The average particle diameter of the cerium oxide particles in the polishing liquid thus prepared is preferably 0.01 μm to 1.0 μm, more preferably 0.08 μm to 0.5 μm, and 0.08 μm to 0.4 μm. Further preferred. If this average particle size is 0.01 μm or more, a high level of polishing rate tends to be achieved more reliably, and if it is 1.0 μm or less, there is a tendency to prevent polishing scratches from entering the film to be polished.

  In the present invention, the average particle diameter of the cerium oxide particles in the polishing liquid refers to the median value of the volume distribution measured with a laser diffraction particle size distribution meter. Specifically, it is a value obtained using LA-920 manufactured by Horiba. In the measurement, the slurry is dropped so that the LA-920 measurement transmittance (H) is 60 to 70%, and the average particle diameter is obtained from the arithmetic average diameter obtained at that time. When determining the aggregation of abrasive grains, it can be determined by measuring the median with LA-920. Hereinafter, the average particle diameter in the present invention is the median value of the measured values of the particle size distribution analyzer LA-920. In general, when particles are dispersed in a liquid, they behave differently from a dry state and exist as primary particles, a plurality of aggregated states, or a mixed state of primary particles and aggregates. Further, the presence state (dispersion state) varies depending on the environment in which the particles are placed, and varies depending on, for example, the pH of the polishing liquid, the type and amount of chemical components, and the like. For this reason, the average particle diameter of the cerium oxide particles in the polishing liquid generally shows a different value from the average particle diameter measured by microscopic observation such as SEM and TEM.

  In the present invention, the cerium oxide particle concentration in the polishing liquid is preferably 0.2% by mass to 2.0% by mass. Especially, it is more preferable that it is 0.3 mass% or more at the point which tends to achieve a high level polishing rate more reliably, and it is further more preferable that it is 0.5 mass% or more. Moreover, 1.0 mass% or less is more preferable, and 0.8 mass% or less is further more preferable at the point which can reduce a grinding | polishing damage | wound.

  When the polishing slurry for CMP of the present invention is used for polishing in the manufacture of semiconductor elements, for example, the content of alkali metals such as sodium ions and potassium ions, halogen atoms, and sulfur atoms in the total dispersant is determined by CMP. It is preferable to keep the mass ratio to 10 ppm or less with respect to the polishing liquid in which the polishing additive and the cerium oxide slurry are combined.

(Dispersant)
In the polishing slurry for CMP of the present invention, a dispersant for dispersing the inorganic abrasive in water is blended. Such a dispersant is not particularly limited as long as it is a compound that can be dissolved in water and has a function of dispersing an inorganic abrasive in water, but the solubility in water is 0.1% by mass to 99%. .9% by mass of a polymer dispersant is preferable. Specifically, for example, a water-soluble organic polymer, a water-soluble anionic surfactant, a water-soluble nonionic surfactant, and a water-soluble zwitterionic surfactant are used. Can be mentioned. These can be used alone or in combination of two or more. Among these, a water-soluble organic polymer and a water-soluble anionic surfactant are preferable from the viewpoint of good cleaning performance of the wafer.

  The blending amount of the dispersing agent is preferably 0.001% by mass or more, more preferably 0.005% by mass or more with respect to the total amount of the polishing slurry for CMP in that the inorganic abrasive can be sufficiently dispersed. Is more preferable, and it is more preferable that it is 0.01 mass% or more. In addition, it is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, based on the total amount of the polishing slurry for CMP, in that it does not cause a reduction in the polishing rate of the silicon oxide film while maintaining good acidity. 0.5 mass% or less is more preferable.

Examples of the water-soluble organic polymer include:
(1) A polymer of a carboxylic acid monomer having an unsaturated double bond such as acrylic acid, methacrylic acid, alkylacrylic acid, maleic acid, fumaric acid, itaconic acid;
(2) a polymer of a compound having an unsaturated double bond such as acrylamide, acrylamide sulfonic acid, styrene sulfonic acid, polyvinyl alcohol;
(3) A copolymer of a carboxylic acid monomer and a monomer having an unsaturated double bond other than the carboxylic acid monomer;
Etc. Among them, an acrylic acid polymer such as a polymer of acrylic acid and a copolymer of acrylic acid and methacrylic acid is preferable in terms of good dispersibility of the abrasive grains. Moreover, it can also be used in combination of 2 or more types containing at least 1 type of the said acrylic acid type polymer, and at least 1 type chosen from the other dispersing agent.

  In the present invention, when an acrylic acid polymer is used, its weight average molecular weight is preferably 2,000 or more in view of good dispersibility. The weight average molecular weight is preferably 500,000 or less, and more preferably 50,000 or less, from the viewpoint that the acrylic acid polymer is easily adsorbed uniformly on the polished surface.

The weight average molecular weight (Mw) can be measured using GPC under the following conditions, for example.
(conditions)
Sample: 10 μL
Standard polystyrene: Standard polystyrene manufactured by Tosoh Corporation (molecular weight: 190000, 17900, 9100, 2980, 578, 474, 370, 266)
Detector: manufactured by Hitachi, Ltd., RI-monitor, trade name “L-3000”
Integrator: Hitachi, Ltd., GPC integrator, product name “D-2200”
Pump: manufactured by Hitachi, Ltd., trade name “L-6000”
Degassing device: Showa Denko Co., Ltd., trade name "Shodex DEGAS"
Column: Hitachi Chemical Co., Ltd., trade names “GL-R440”, “GL-R430”, “GL-R420” connected in this order and used as eluent: tetrahydrofuran (THF)
Measurement temperature: 23 ° C
Flow rate: 1.75 mL / min Measurement time: 45 minutes

  In addition, it is preferable to use a water-soluble anionic surfactant as the dispersant because the cleaning property of the wafer is good. Examples of the water-soluble anionic surfactant include lauryl sulfate triethanolamine, ammonium lauryl sulfate, polyoxyethylene alkyl ether sulfate triethanolamine, alpha sulfo fatty acid ester salt (α-SFE), alkylbenzene sulfonate (ABS). Alkyl sulfate (AS), alkyl ether sulfate (AES), alkyl sulfate triethanolamine, phosphate ester, polymerized polymer sulfate, polymerized polymer carboxylate, and the like.

(Conductivity adjuster)
The conductivity adjusting agent used in the present invention is preferably a compound that provides one or more selected from inorganic cations, inorganic anions, organic cations and organic anions, and salts thereof.

Although there is no restriction | limiting in particular as said inorganic cation, A monovalent-10 valent thing is preferable, and the following are mentioned specifically.
Hydrogen ion (H ⁺ ), lithium ion (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), silver ion (Ag ⁺ ), copper (I) ion (Cu ⁺ ), mercury (I) ion (Hg ⁺ ), oxonium ion (H ₃ O ⁺ ), ammonium ion (NH ₄ ⁺ ), diammine silver ion ([Ag (NH ₃ ) ² ] ⁺ ), violeo ([CoCl ₂ (NH ₃ ) ₄ ] ⁺ ) Monovalent cations;
Magnesium ion (Mg ²⁺ ), calcium ion (Ca ²⁺ ), strontium ion (Sr ²⁺ ), barium ion (Ba ²⁺ ), cadmium ion (Cd ²⁺ ), nickel (II) ion (Ni ²⁺ ), zinc ion (Zn ²⁺⁾ ), Copper (II) ion (Cu ²⁺ ), mercury (II) ion (Hg ²⁺ ), iron (II) ion (Fe ²⁺ ), cobalt (II) ion (Co ²⁺ ), tin (II) ion (Sn ²⁺ ) ), Lead (II) ion (Pb ²⁺ ), manganese (II) ion (Mn ²⁺ ), tetraammine zinc (II) ion ([Zn (NH ₃ ) ₄ ] ²⁺ ), tetraammine copper (II) ion ([Cu ( NH ₃ ) ₄ ] ²⁺ ), tetraaqua copper (II) ion ([Cu (H ₂ O) ₄ ] ²⁺ ), thiocyanoiron (I II) ion ([Fe (SCN)] ²⁺ ), hexaammine nickel (II) ion ([Ni (NH ₃ ) ₆ ] ²⁺ ), purpleo ([CoCl (NH ₃ ) ₅ ] ²⁺ ), palladium (II) ion Divalent cations such as (Pd ²⁺ ), platinum (II) ions (Pt ²⁺ );
Aluminum ions (Al ³⁺ ), iron (III) ions (Fe ³⁺ ), chromium (III) ions (Cr ³⁺ ), hexaammine cobalt (III) ions ([Co (NH ₃ ) ₆ ] ³⁺ ), hexaaqua cobalt ( III) ions ([Co (H ₂ O) ₆ ] ³⁺ ), hexaammine chromium (III) ions ([Cr (NH ₃ ) ₆ ] ³⁺ ), roseo ([Co (NH ₃ ) ₄ (H ₂ O) ₂ ] A trivalent cation such as ³⁺ );
Tetravalent cations such as tin (IV) ion (Sn ⁴⁺ ).
These can be used alone or in combination of two or more.

  Among the compounds that give inorganic cations, one or more selected from the group comprising hydrogen ions, potassium ions, lithium ions, silver ions, copper (I) ions, ammonium ions, and mixtures thereof are given. The compound is more preferable in that it is easily available and has a good effect.

The inorganic anion is not particularly limited, but monovalent to monovalent ones are preferable, and specific examples include the following.
Hydride ion (H ⁻ ) fluoride ion (F ⁻ ), chloride ion (Cl ⁻ ), bromide ion (Br ⁻ ), iodide ion (I ⁻ ) hydroxide ion (OH ⁻ ), cyanide ion ( CN ⁻ ), nitrate ion (NO ₃ ⁻ ), nitrite ion (NO ₂ ⁻ ), hypochlorite ion (ClO ⁻ ), chlorite ion (ClO ₂ ⁻ ), chlorate ion (ClO ₃ ⁻ ), Perchlorate ion (ClO ₄ ⁻ ), permanganate ion (MnO ₄ ⁻ ), dihydrogen phosphate ion (H ₂ PO ₄ ⁻ ), hydrogen sulfate ion (HSO ₄ ⁻ ), hydrogen sulfide ion (HS ⁻ ), Thiocyanate ion (SCN ⁻ ), tetrahydroxoaluminate ion ([Al (OH) ₄ ] ⁻ , [Al (OH) ₄ (H ₂ O) ₂ ] ⁻ ), dicyanosilver (I) acid ion ([Ag ( CN) ] ^-), tetra hydroxo chromium (III) ion _{([Cr (OH) 4]} -), tetrachloroaurate (III) ion ([AuCl _4] ^-) monovalent such anions;
Oxide ion (O ²⁻ ), sulfide ion (S ²⁻ ), peroxide ion (O ₂ ²⁻ ), sulfate ion (SO ₄ ²⁻ ), sulfite ion (SO ₃ ²⁻ ), thiosulfate ion (S ₂ O ₃ ²⁻ ), carbonate ion (CO ₃ ²⁻ ), bicarbonate ion (HCO ₃ ⁻ ), chromate ion (CrO ₄ ²⁻ ), dichromate ion (Cr ₂ O ₇ ²⁻ ), Monohydrogen phosphate ion (HPO ₄ ²⁻ ), tetrahydroxozinc (II) acid ion ([Zn (OH) ₄ ] ²⁻ ), tetracyanozinc (II) acid ion ([Zn (CN) ₄ ] ²⁻ ) , Divalent anions such as tetrachlorocopper (II) ion ([CuCl ₄ ] ²⁻ );
Phosphate ion (PO ₄ ³⁻ ), hexacyanoferrate (III) ion ([Fe (CN) ₆ ] ³⁻ ), bis (thiosulfato) silver (I) acid ion ([Ag (S ₂ O ₃ ) ₂ ] ^3- ) trivalent anions such as;
Tetravalent anions such as hexacyanoferrate (II) ion ([Fe (CN) ₆ ] ⁴⁻ ).
These can be used alone or in combination of two or more.

  Among the compounds that give inorganic anions, fluoride ion, chloride ion, bromide ion, iodide ion, hydroxide ion, cyanide ion, nitrate ion, More preferred are compounds that provide one or more selected from the group comprising nitrate ions, dihydrogen phosphate ions and mixtures thereof.

  Moreover, said organic cation and organic anion are the organic cation and organic anion which arise when a predetermined organic compound or its salt ionizes in polishing liquid. Examples of the compound that gives such organic cation and organic anion include arylamine, amino alcohol, alcohol, aldehyde, ketone, quinone, aliphatic amine, nitro compound, heterocyclic amine, aminocarboxylic acid, saturated carboxylic acid, cyclic mono One or more selected from carboxylic acids, unsaturated monocarboxylic acids, phenols, sulfonamides, thiols, ethers, sulfonic acids and halogenated organic compounds and salts thereof are preferred.

  In addition, the above organic cation and organic anion have an amino group, tertiary amino group, secondary amino group, carboxylic acid, hydroxyl group, amide, aldehyde group, ketone, sulfonamide, thiol, nitro group as functional groups. It preferably has one or more functional groups selected from halogen compounds, sulfonic acids, cyano groups and oximes.

  Examples of organic compounds that give organic cations and organic anions and salts thereof include ascorbic acid, oxalic acid, citric acid, malonic acid, aspartic acid, ortho-aminobenzoic acid, para-aminobenzoic acid, and 2-aminoethyl. Phosphonic acid, alanine, arginine, isonicotinic acid, isoleucine, oxaloacetate, ornithine, guanosine, glycine, 2-glycerin phosphate, paraglucose-1-phosphate, glutamine, glutamic acid, ortho-chloroaniline, acetic acid, acetate, Chloroacetic acid, salicylic acid, sarcosine, cyanoacetic acid, 1,2,4-diaminobutyric acid, dichloroacetic acid, cysteine, N, N-dimethylglycine, tartaric acid, tyrosine, trichloroacetic acid, threonine, nicotinic acid, nitroaniline, nitroacetic acid, picrine Acid, picolinic acid, hiss Gin, proline, maleic acid, lysine, leucine, ethylamine, diethylamine, triethylamine, diphenylguanidine, piperidine, butylamine, dibutylamine, isopropylamine, tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium fluoride Ride, tetrabutylammonium hydroxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium fluoride, tetramethylammonium nitrate, tetramethylammonium acetate, tetramethylammonium propionate, tetramethylammonium maleate, tetra Methylammonium sulfate, urea, Imidazole, pyridine, triazole, 2-aminoethanol, or derivatives thereof. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Among the compounds that give organic cations and organic anions, tetramethylammonium hydroxide, triethylamine, acetate, ethylamine, picolinic acid, glutamic acid, oxalic acid, and derivatives thereof are more preferable.

  In the case where a salt is used among the above conductivity adjusting agents, the effect of the present invention that a high polishing rate can be achieved is the case where a water-soluble anionic polymer compound is used as a dispersing agent or inorganic polishing. It becomes more prominent when cerium oxide is used as an agent, and is particularly prominent when cerium oxide and a water-soluble anionic polymer compound are used in combination.

  The case where a water-soluble anionic polymer compound is used will be described in more detail. In general, when an inorganic abrasive such as cerium oxide is dispersed with a water-soluble anionic polymer, the dispersion is caused by repulsion between anion sites of the polymer chain. As an index for confirming this repulsion, a zeta potential which is a surface potential (also referred to as an electrokinetic potential) is suitable. That is, since the polymer is dispersed while the zeta potential is negative, the degree of repulsion can be confirmed based on the magnitude of the zeta potential.

  On the other hand, a film to be polished such as a silicon oxide film usually has a negative zeta potential and repels anion sites.

As shown in the schematic diagram of FIG. 2, the dispersion state is such that the abrasive grains 6 are surrounded by a water-soluble anionic polymer compound 7 having a polymer chain 71 and an anionic portion 72, and the anionic portions 72 are repelled. Therefore, it is estimated that the three-dimensionally bulky state is obtained.
The reason why the polishing rate can be improved by adding a small amount of salt in the present invention is that, as shown in the schematic diagram of FIG. It is presumed that the electric particles are suppressed and the three-dimensional repulsion of the polymer chain can be suppressed, so that the abrasive particles are easily brought close to the film to be polished such as a silicon oxide film.

  In this respect, the index of the amount of the salt can be confirmed by the conductivity of the CMP polishing liquid. In the CMP polishing liquid, the conductivity is 8 mS / m to 1000 mS / m, and the pH is 3.0 to The inventors of the present invention have found that a sufficient polishing rate is expressed by setting the value to 7.0.

  Further, among the above-described conductivity adjusting agents, for example, the polishing rate can be increased by adding an inorganic acid. In this case, protons are trapped in the anion portion of the water-soluble polymer, and it is presumed that, as described above, there is an effect of suppressing the repulsion of the anion portion and improving the polishing rate.

  When repulsion of the anion site is suppressed by protons, the compounding amount index can be confirmed by the zeta potential, and as the compounding amount increases, the zeta potential shifts to the positive side, and the negative electrode potential such as a silicon oxide film having a negative potential is shifted. It shows that repulsion with the polishing film is suppressed.

  As described above, according to the polishing slurry for CMP of the present invention, when the electrical conductivity is 8 mS / m to 1000 mS / m and the pH is 3.0 to 7.0, the repulsion of the dispersant does not aggregate. Therefore, the polishing rate can be remarkably improved, the polishing rate can be stabilized at a high level, and variations in the polishing rate can be suppressed.

  The conductivity of the polishing slurry for CMP of the present invention needs to be 8 mS / m to 1000 mS / m as described above. The conductivity of the polishing slurry for CMP is preferably 10 mS / m or more, more preferably 13 mS / m or more, in that the polishing rate is further improved and the variation in the polishing rate is small and can be stabilized. More preferably, it is particularly preferably 16 mS / m or more, and very preferably 20 mS / m or more. On the other hand, if the conductivity adjusting agent is added too much, it tends to aggregate due to the salting out effect. However, by setting the conductivity to 1000 mS / m or less, the polishing rate is sufficiently suppressed while sufficiently suppressing the aggregation of particles in the polishing liquid. Effects such as improvement can be obtained effectively. For the same reason, the electrical conductivity is preferably 500 mS / m or less, more preferably 250 mS / m or less, particularly preferably 120 mS / m or less, and extremely preferably 60 mS / m or less. . The presence / absence of aggregation can be determined, for example, by measuring the particle size of the inorganic abrasive in the polishing liquid for CMP with a laser diffraction particle size distribution analyzer such as LA-920. When the abrasive grains are agglomerated, it leads to an increase in polishing scratches, which is not preferable.

  Further, the blending amount of the conductivity adjusting agent is appropriately selected so that the conductivity of the polishing slurry for CMP is 8 mS / m to 1000 mS / m. Furthermore, the optimum blending amount of the conductivity adjusting agent is preferably appropriately selected according to the type and blending amount of each component contained in the CMP polishing liquid. Specific factors include, for example, (1) amount of dispersant, (2) type of inorganic abrasive, (3) amount of inorganic abrasive, and (4) average particle size of inorganic abrasive (specified above). (Median value of LA-920), (5) pH of polishing liquid for CMP, and the like.

  For example, (1) When the blending amount of the dispersant contained in the CMP polishing liquid is large (for example, when it is 10% by mass or more with respect to the whole CMP polishing liquid), the inorganic abrasive grains are dispersed even if the conductivity is higher. However, it is considered that the polishing rate may decrease as the blending amount of the dispersant increases.

  Further, (2) if the kind of inorganic abrasive is different, the amount of dispersing agent adsorbed on the inorganic abrasive particles is also different, and the electrical conductivity that is the basis for increasing the polishing rate is also considered to be different. In addition, although the example at the time of using cerium oxide as an inorganic abrasive | polishing agent was demonstrated above, even when another inorganic abrasive | polishing agent is used, the electrical conductivity of polishing liquid for CMP shall be 8 mS / m-1000 mS / m, and pH It has been confirmed that a desired effect can be obtained by setting the ratio to 3.0 to 7.0, and the inorganic abrasive according to the present invention is not limited to cerium oxide.

  Further, (3) when the amount of the inorganic abrasive is large (for example, when it is 10% by mass or more with respect to the entire CMP polishing liquid), the polishing rate increases, but on the other hand, the inorganic abrasive particles per unit volume. The concentration at which the particles are dispersed increases, and the particles tend to aggregate. The blending amount of the conductivity adjusting agent in this case depends on the relationship with the elements shown in (1), (2), (4), and (5), but from the viewpoint of suppressing the aggregation of the inorganic abrasive. It is preferable to select such that the electrical conductivity of the polishing slurry is within the range of 8 mS / m to 20 mS / m.

For example, (4) when the average particle size of the abrasive grains in the polishing liquid of the inorganic abrasive is small (for example, less than 0.08 μm), the average particle diameter of the abrasive grains in the polishing liquid is large In comparison, even if the same amount of inorganic abrasive is present in terms of weight percentage, the particle concentration per unit volume is large and the environment tends to aggregate. Therefore, when the average particle size of the inorganic abrasive is small, a sufficient amount of inorganic polishing is required in order to prevent a decrease in the polishing rate while taking into consideration that the number of particles tends not to be the same as when the average particle size is large. It is desirable to add an agent.

  Further, for example, (5) When the pH of the polishing slurry for CMP is low (for example, when pH is less than 3.0), it is considered that the conductivity is difficult to increase. That is, when the pH is low, the polishing liquid is an environment in which a large amount of protons are present, and when the blending amount (concentration) of the conductivity adjusting agent is increased, the inorganic abrasive tends to aggregate easily.

  When the inorganic cation of the conductivity adjusting agent is a proton, the blending amount of the conductivity adjusting agent is such that the zeta potential of the polishing liquid is preferably −60 mV or more, more preferably −40 mV or more, and further preferably −30 mV or more. It is desirable to select as follows. As the zeta potential of the polishing liquid approaches 0, the repulsion between the inorganic abrasive particles and the film to be polished such as a silicon oxide film is suppressed, and the polishing rate tends to be improved. However, it is desirable that the zeta potential be close to 0 so that the inorganic abrasive particles do not aggregate.

  The conductivity adjusting agent is preferably added to such an extent that the inorganic abrasive particles do not agglomerate. For this reason, the blending amount is usually a small amount with respect to the entire polishing liquid. By this very small amount of conductivity adjusting agent, it is possible to stabilize at a high polishing rate and to reduce variations in the polishing rate. As a preferable blending amount, 0.0001 mol / L to 0.01 mol / L can be exemplified based on the total amount of the polishing slurry for CMP.

(PH)
The pH of the polishing slurry for CMP of the present invention needs to be in the range of 3.0 to 7.0, and preferably in the range of 3.0 to 6.0, from the viewpoint of improving the polishing rate. More preferably, it is in the range of 3.0 to 5.0.

  The pH is correlated with the zeta potential of the polishing liquid. The lower the pH, the more protons in the polishing liquid, and the zeta potential approaches zero from minus. Therefore, repulsion with a film to be polished such as a silicon oxide film having a negative zeta potential is reduced, leading to an improvement in the polishing rate. Examples of the inorganic abrasive exhibiting such a tendency include at least cerium-based abrasive grains, alumina, and silica.

  Note that when the pH is decreased, the polishing rate tends to be improved, but at the same time, the abrasive particles tend to aggregate easily.

(Supply form of polishing liquid for CMP)
When supplying the CMP polishing liquid of the present invention to the film to be polished, a polishing liquid containing all of the above components may be prepared in advance and the polishing liquid may be supplied to the film to be polished. A part of the components may be prepared as separate liquids, and these liquids may be supplied to the film to be polished. For example, in the latter supply form, the CMP polishing liquid of the present invention is a two-component type polishing liquid comprising a liquid obtained by blending the first component group and a liquid obtained by blending the second component group. It is good. More specifically, an embodiment in which the first component group is an inorganic abrasive and a dispersant, the second component group is a conductivity adjusting agent, and these are separate liquids. Further, combinations other than those shown here can be used and are not particularly limited.

  A two-component type polishing liquid is preferable because it can more reliably prevent aggregation of cerium oxide particles during storage, further deterioration of polishing scratches due to aggregation and fluctuation of the polishing rate.

  Although it does not restrict | limit especially as a solvent used for polishing liquid by this invention, Water is preferable and deionized water and ultrapure water are further more preferable. Moreover, you may contain polar solvents, such as solvents other than water, ethanol, acetic acid, acetone, etc. as needed.

(CMP polishing)
In the substrate polishing method of the present invention, a substrate on which a film to be polished is formed is pressed against a polishing cloth of a polishing surface plate and pressurized, and the CMP polishing liquid of the present invention is supplied between the polishing film and the polishing cloth. The film to be polished is polished by relatively moving the substrate and the polishing surface plate. The substrate polishing method of the present invention is particularly suitable for a polishing step of polishing a substrate having a step on the surface to flatten the step.

  Hereinafter, the polishing method will be described by taking as an example the case of a semiconductor substrate on which an inorganic insulating layer such as a silicon oxide film, a silicon nitride film, or a polycrystalline silicon film is formed.

  As a polishing apparatus used in the polishing method of the present invention, for example, a holder for holding a substrate having a film to be polished such as a semiconductor substrate, and a motor capable of attaching a polishing cloth (pad) and capable of changing the rotation speed A general polishing apparatus or the like having a polishing surface plate to which the above is attached can be used.

  Examples of the polishing apparatus include EPO-111 manufactured by Ebara Manufacturing Co., Ltd., MIRRA 3400 manufactured by AMAT, and a Reflection polishing machine. There is no restriction | limiting in particular as abrasive cloth, For example, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used. It is preferable that the polishing cloth is grooved so that a polishing slurry for CMP is accumulated.

The polishing conditions are not particularly limited, but the rotation speed of the polishing platen is preferably a low rotation of 200 min ⁻¹ or less from the viewpoint of preventing the semiconductor substrate from jumping out. The pressure applied to the semiconductor substrate (processing load or polishing load) is preferably 100 kPa or less from the viewpoint of preventing scratches after polishing.

  While polishing the film to be polished, it is preferable to continuously supply the polishing slurry for CMP to the polishing cloth with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of polishing cloth is always covered with polishing liquid.

  After the polishing, the semiconductor substrate is preferably thoroughly washed in running water, and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like.

  Thus, by polishing the inorganic insulating layer, which is a film to be polished, with the above polishing liquid, surface irregularities can be eliminated and a smooth surface can be obtained over the entire surface of the semiconductor substrate. By repeating this step a predetermined number of times, a semiconductor substrate having a desired number of layers can be manufactured.

Examples of the method for producing a silicon oxide film using the polishing slurry for CMP of the present invention include a low pressure CVD method and a plasma CVD method. Silicon oxide film formation by low-pressure CVD uses monosilane: SiH ₄ as the Si source and oxygen (O ₂ ) as the oxygen source. It can be obtained by performing this SiH ₄ —O ₂ oxidation reaction at a low temperature of 400 ° C. or lower. In some cases, heat treatment is performed at a temperature of 1000 ° C. or lower after CVD.

When doping phosphorus: P in order to achieve surface flattening by high-temperature reflow, it is preferable to use a SiH ₄ —O ₂ —PH ₃ -based reactive gas. The plasma CVD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium. There are two plasma generation methods, capacitive coupling type and inductive coupling type.

The reaction as a gas, SiH ₄ as an Si source, an oxygen source as _{N 2} O was used was _SiH 4 -N ₂ O-based gas and _{TEOS-O 2} based gas using tetraethoxysilane (TEOS) in an Si source (TEOS- Plasma CVD method).

  The substrate temperature is preferably in the range of 250 ° C. to 400 ° C., and the reaction pressure is preferably in the range of 67 to 400 Pa.

The silicon oxide film polished in the present invention may be doped with an element such as phosphorus or boron. Similarly, the silicon nitride film formation by the low pressure CVD method uses dichlorosilane: SiH ₂ Cl ₂ as the Si source and ammonia: NH ₃ as the nitrogen source.

It can be obtained by performing this SiH ₂ Cl ₂ —NH ₃ oxidation reaction at a high temperature of 900 ° C. In the plasma CVD method, examples of the reactive gas include SiH ₄ —NH ₃ -based gas using SiH ₄ as the Si source and NH ₃ as the nitrogen source. The substrate temperature is preferably 300 ° C to 400 ° C.

  Semiconductor substrates to which the present invention is applied include individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, thyristors, DRAMs (dynamic random access memories), SRAMs (static random access memories), EPROM (Erasable Programmable Read Only Memory), Mask ROM (Mask Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), Flash Memory and other Memory Elements, Microprocessor, Theoretical circuit elements such as DSP and ASIC, integrated circuit elements such as compound semiconductors represented by MMIC (monolithic microwave integrated circuit), hybrid integrated circuits (hybrid IC), Photodiode, a substrate containing such a photoelectric conversion element such as a charge coupled device and the like.

  The polishing liquid for CMP of the present invention includes not only a silicon nitride film and a silicon oxide film formed on a semiconductor substrate, but also an inorganic insulating film such as a silicon oxide film, glass, and silicon nitride formed on a wiring board having a predetermined wiring. It is possible to polish a film mainly containing polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN or the like.

The electronic component of the present invention uses a substrate polished by the above polishing method. The electronic component according to the present invention includes not only a semiconductor element but also an optical glass such as a photomask, a lens, and a prism, an inorganic conductive film such as ITO, glass and a crystalline material, an optical integrated circuit, an optical switching element, and an optical element. Includes optical waveguides, optical fiber end faces, scintillator and other optical single crystals, solid state laser single crystals, blue laser LED sapphire substrates, SiC, GaP, GaAs and other semiconductor single crystals, magnetic disk glass substrates, magnetic heads, etc. .

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Example 1]
(Preparation of cerium oxide ground powder)
40 kg of cerium carbonate hydrate was placed in an alumina container and calcined in air at 830 ° C. for 2 hours to obtain 20 kg of a yellowish white powder. When this powder was phase-identified by X-ray diffraction, it was confirmed to be cerium oxide. When the sintered cerium oxide powder particles were observed by SEM, a polycrystalline body having a crystal grain boundary was observed, and the crystallite size of the polycrystalline particles was in the range of 20 to 100 μm.
Next, 20 kg of the cerium oxide powder was dry pulverized using a jet mill. As a result of measuring the specific surface area of the polycrystal by the BET method, it was 9.4 m ² / g.

(Preparation of cerium oxide slurry)
Mix 15.0 kg of cerium oxide powder and 151.07 kg of deionized water, add 600 g of a commercially available polyacrylic acid aqueous solution (weight average molecular weight 8000, concentration 40% by weight) as a dispersing agent, and stir for 10 minutes. Ultrasonic irradiation was performed in the pipe for feeding the liquid while feeding the liquid to the container (500 mL beaker). The ultrasonic frequency was 400 kHz, and the solution was fed over 30 minutes.

  In this way, 500 g ± 20 g of the cerium oxide dispersion was fed into four 500 mL beakers, and then centrifuged. Centrifugation was performed under the condition that the centrifugal force applied to the outer periphery was set to 500 G for 2 minutes to remove cerium oxide that had settled to the bottom of the beaker.

The solid content concentration of the obtained cerium oxide dispersion was measured and found to be 7.0%.
Subsequently, it diluted with deionized water so that solid content concentration might be 0.5 mass%, and the cerium oxide slurry was obtained. The slurry had a pH value of 4.2.

  Furthermore, using a laser diffraction particle size distribution analyzer (trade name: LA-920, manufactured by HORIBA, Ltd.), the refractive index was 1.93 and the transmittance was 68%. The value was 240 nm. Impurity ions (Na, K, Fe, Al, Zr, Cu, Si, Ti) in the cerium oxide slurry measured using an atomic absorption photometer (manufactured by Shimadzu Corporation, model number: AA-6650) are: It was 1 mass ppm or less.

(Preparation of polishing liquid)
Next, an aqueous ammonium nitrate solution as a conductivity adjusting agent was added to the cerium oxide slurry obtained above to obtain a polishing liquid having a pH of 4.0 and a conductivity of 7.91 mS / m.

(Measurement of polishing rate)
An STI pattern wafer (Advantech's Sematech 864) was used as a test wafer for insulating film CMP evaluation. The test wafer is set in a holder of a polishing apparatus (Applied Material, trade name: Mirra 3400) to which a holding pad for attaching a substrate to be held is attached. On the other hand, a polishing platen having a diameter of 500 mm is made of a porous urethane resin. A polishing pad (k-groove groove, manufactured by Rodel, model number: IC-1400) was attached.

  The holder with the insulating film surface down was placed on the polishing pad, and the inner tube pressure, the retainer ring pressure, and the membrane pressure were set to 28 kPa, 38 kPa, and 28 kPa, respectively.

  While the polishing liquid prepared above was dropped on the surface plate at a flow rate of 200 mL / min, the surface plate and the wafer were operated at 93 (1 / min) and 87 (1 / min), respectively, and the STI pattern wafer film (Sematech 864) was polished for 40 seconds. The polished wafer was thoroughly washed with a PVA brush and pure water and then dried.

  Then, using an optical interference film thickness apparatus (Dainippon Screen Mfg. Co., Ltd., trade name: RE-3000), the remaining film thickness of the STI pattern wafer (Trench / Active = 100/100 μm) and the wafer surface The remaining film thickness of the 60 silicon oxide films was measured, and the polishing rate was calculated from the decrease in film thickness from before the polishing. The obtained results are shown in Table 1.

[Examples 2 to 4]
In Examples 2 and 3, polishing liquids having the pH and conductivity shown in Table 1 were prepared in the same manner as in Example 1 except that the addition amount of the ammonium nitrate aqueous solution was changed. In Example 4, a polishing liquid having the pH and conductivity shown in Table 1 was prepared in the same manner as in Example 1 except that a potassium chloride aqueous solution was used instead of the ammonium nitrate aqueous solution. Next, the polishing rate was measured in the same manner as in Example 1 using the polishing liquids of Examples 2 to 4. The obtained results are shown in Table 1.

[Comparative Examples 1-8]
In Comparative Examples 1-7, the polishing liquid which has pH and electrical conductivity shown in Table 1 was prepared, respectively, without using an electrical conductivity modifier. In Comparative Example 8, a polishing liquid having the pH and conductivity shown in Table 1 was prepared in the same manner as in Example 1 except that the addition amount of the aqueous ammonium nitrate solution was changed. Subsequently, the polishing rate was measured in the same manner as in Example 1 using the polishing liquids of Comparative Examples 1 to 8. The obtained results are shown in Table 1.

  Further, the correlation between the conductivity of the polishing liquid obtained from Examples 1 to 4 and Comparative Examples 1 to 8 and the thickness of the remaining film after polishing of the STI pattern wafer Trench part / Active part = 100/100 μm is shown in FIG. Shown in

[Examples 5 and 6, Comparative Examples 9 to 12]
In Examples 5 and 6 and Comparative Examples 9 to 11, a polishing liquid having the pH and conductivity shown in Table 2 was used in the same manner as in Example 1 except that a predetermined amount of an aqueous ammonium nitrate solution or an aqueous potassium chloride solution was used. Was prepared. Further, as a polishing liquid of Comparative Example 12, a ceria slurry manufactured by Hitachi Chemical Co., Ltd. and having a GPX series pH of about 8 was prepared.

  Next, the polishing rate was measured in the same manner as in Example 1 using the polishing liquids of Example 5 and Comparative Examples 9-12. Moreover, zeta potential was measured about each polishing liquid. The zeta potential was measured using a ZETERSIZER 3000HS A manufactured by MALVERN. The obtained results are shown in Table 2. Moreover, the relationship between pH obtained from Example 5 and Comparative Examples 9-11 and zeta potential is shown in FIG.

[Examples 7 and 8]
In Example 7, in place of the ammonium nitrate aqueous solution, the same procedure as in Example 1 was conducted except that nitric acid and a tetramethylammonium hydroxide (TMAH) 25% aqueous solution (manufactured by Tama Chemical Industry Co., Ltd.) were used. The abrasive | polishing agent shown in FIG. In Example 8, a polishing liquid shown in Table 3 was prepared in the same manner as in Example 1 except that potassium hydroxide and picolinic acid were used instead of the ammonium nitrate aqueous solution.

  Next, the polishing rate was measured in the same manner as in Example 1 using the polishing liquids of Examples 7 and 8. The obtained results are shown in Table 3. Table 3 also shows the results of Example 1.

  From Table 3, when an inorganic cation and an inorganic anion are combined (Example 1), when an organic cation and an inorganic anion are combined (Example 7), an inorganic cation and an organic anion are used. It can be seen that a sufficient polishing rate can be achieved in combination.

  In the description of the present invention, the term “including” or the like means that the term is not limited unless otherwise specified. The method of the present specification can be carried out in any order as long as there is no particular limitation. The examples, comparative examples, and exemplary phrases set forth herein are merely illustrative of the present invention and, unless specifically claimed, are within the scope of the present invention. There is no limit.

The inventors have described the best mode for carrying out the invention in the specification. When the above description is read by a person skilled in the art, preferred variants similar to these may become apparent. The present inventors are fully aware that the present invention is implemented in different forms, and consider that the patent is sufficiently effective for similar forms of inventions to which the basis of the present invention is applied.
Moreover, the present invention can use, as its principle, all variations of the contents listed in the claims of the patent scope, and any combination of various elements described above.
Any and all possible combinations thereof are included herein in the present invention unless otherwise limited, and unless expressly denied by context.

It is a schematic cross section which shows the board | substrate in the semiconductor shallow trench isolation | separation process, (a) shows the board | substrate before grinding | polishing, (b) shows the board | substrate in the middle of grinding | polishing, (c) shows the board | substrate after grinding | polishing, respectively. It is a conceptual diagram which shows the relationship between water-soluble anionic polymer and an abrasive grain. It is a conceptual diagram which shows the relationship between a water-soluble anion, an abrasive grain, and the salt of an opposite charge. It is a graph which shows the correlation with the electrical conductivity of polishing liquid obtained from Examples 1-4 and Comparative Examples 1-8, and the thickness of the remaining film after STI pattern wafer Trench part / Active part = 100/100 micrometer grinding | polishing. . It is a graph which shows the relationship between pH obtained from Example 5 and Comparative Examples 9-11, and zeta potential.

Explanation of symbols

1 Silicon substrate 2 Stopper film (silicon nitride film)
3 Silicon oxide film 4 Elevation difference of silicon oxide film thickness 5 Element embedded portion 6 Abrasive grain 7 Water-soluble anionic polymer compound 71 Polymer chain 72 Anionic site 8 Salt of opposite charge

Claims (18)

Conductivity adjusting agent, a polishing liquid for ing CMP by blending a mineral abrasive and dispersing agent,
The conductivity is 8 mS / m to 1000 mS / m,
pH is 3.0 to 7.0 der is,
The dispersant comprises at least one selected from the group consisting of a water-soluble organic polymer that is a water-soluble anionic polymer compound, and a water-soluble anionic surfactant,
The inorganic abrasive has a zeta potential of −35 mV or more and less than 0 mV in the CMP polishing liquid;
Polishing liquid for CMP.   The polishing slurry for CMP according to claim 1, wherein the compounding amount of the conductivity adjusting agent is 0.00001 mol / L to 0.01 mol / L.   The polishing slurry for CMP according to claim 1 or 2, wherein the conductivity adjusting agent is a compound that provides one or more selected from inorganic cations, inorganic anions, organic cations and organic anions.   The conductivity adjusting agent is arylamine, amino alcohol, alcohol, aldehyde, ketone, quinone, aliphatic amine, nitro compound, heterocyclic amine, aminocarboxylic acid, saturated carboxylic acid, cyclic monocarboxylic acid, unsaturated monocarboxylic acid It is the 1 type (s) or 2 or more types selected from an acid, phenols, a sulfonamide, a thiol, ether, a sulfonic acid, halogenated organic compounds, and those salts. For CMP as described in any one of Claims 1-3 Polishing fluid.   The conductivity adjusting agent is an amino group, tertiary amino group, secondary amino group, carboxylic acid, hydroxyl group, amide, aldehyde group, ketone, sulfonamide, thiol, nitro group, halogen compound, sulfonic acid, cyano group and The polishing slurry for CMP according to any one of claims 1 to 4, which is a compound that provides an organic cation and / or an organic anion having one or more functional groups selected from oximes.   The inorganic abrasive is one or more selected from cerium-based abrasive grains, alumina, silica, titania, zirconia, magnesia, mullite, silicon nitride, α-sialon, aluminum nitride, titanium nitride, silicon carbide and boron carbide. The polishing slurry for CMP according to any one of claims 1 to 5.   The inorganic abrasive is selected from the group of cerium oxide, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, cerium carbonate The polishing liquid for CMP according to any one of claims 1 to 6, wherein the polishing liquid is at least one cerium-based abrasive.   The polishing slurry for CMP according to any one of claims 1 to 7, wherein the inorganic abrasive is cerium oxide abrasive.   The polishing slurry for CMP according to any one of claims 1 to 8, wherein the inorganic abrasive is a cerium-based abrasive having an average particle size of 0.01 µm to 1.0 µm.   The polishing slurry for CMP according to any one of claims 1 to 9, wherein a blending amount of the inorganic abrasive is 0.05 wt% to 10.00 wt%. CMP polishing slurry according to any one of claims 1 to 10, wherein the dispersant further comprises at least one member selected from water-soluble nonionic surfactant and a water-soluble zwitterionic surfactant. A polymer of a carboxylic acid monomer having an unsaturated double bond as the dispersant, a polymer of a monomer having an unsaturated double bond other than a carboxylic acid monomer having an unsaturated double bond, and 2. The water-soluble organic polymer of one type or two or more types selected from a copolymer of a carboxylic acid monomer and a monomer having an unsaturated double bond other than the carboxylic acid monomer. The polishing liquid for CMP as described in any one of ~ 11 . As the water-soluble organic polymer that is the water-soluble anionic polymer compound,
A polymer of at least one carboxylic acid monomer selected from the group consisting of acrylic acid, methacrylic acid, alkyl acrylic acid, maleic acid, fumaric acid and itaconic acid,
A polymer of at least one compound selected from the group consisting of acrylamide, acrylamide sulfonic acid, styrene sulfonic acid and vinyl alcohol, and
A copolymer of a carboxylic acid monomer and a monomer having an unsaturated double bond other than the carboxylic acid monomer,
The polishing slurry for CMP according to any one of claims 1 to 12, comprising at least one selected from the group consisting of: Examples of the water-soluble anionic surfactant include lauryl sulfate triethanolamine, ammonium lauryl sulfate, polyoxyethylene alkyl ether sulfate triethanolamine, alpha sulfo fatty acid ester salt, alkyl benzene sulfonate, alkyl sulfate, alkyl ether sulfate ester salt And at least one selected from the group consisting of alkylsulfuric acid triethanolamine, phosphate ester salt, polymerized polymer sulfate and polymerized polymer carboxylate. Polishing liquid for CMP. The polishing liquid for CMP as described in any one of Claims 1-13 in which the said dispersing agent contains an acrylic acid polymer.   The polishing slurry for CMP according to any one of claims 1 to 15 is applied to the polishing film and the polishing cloth in a state where the polishing film of the substrate having the polishing film is pressed against a polishing cloth of a polishing surface plate. The substrate polishing method for polishing the film to be polished by relatively moving the substrate and the polishing surface plate while supplying the substrate.   The substrate polishing method according to claim 16, wherein the substrate has a step on the surface of the film to be polished, and the step is flattened by polishing the film to be polished.   An electronic component comprising a substrate polished by the polishing method according to claim 16.

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