Polishing agent and method for producing same, method for producing polishing agent additive liquid, polishing method, and method for producing semiconductor component

Abstract

Provided are a polishing agent whereby it is possible to suppress the occurrence of polishing scratches while improving a selection ratio by using an anionic polymer with a low acid value, a method for producing a polishing agent additive liquid for adjusting the polishing agent, a polishing method using the polishing agent, and a method for producing a semiconductor component using the polishing method. The polishing agent contains abrasive grains, an anionic polymer, and water. The acid value of the anionic polymer is 400 mgKOH / g or less, and X1, X2, and X3 as determined from formulas (1), (2), and (3) indicated below are, respectively, 1.2 or less, 2.0 or less, and 5.0 or less.　Formula (1): X1 = N11 / N12. Formula (2): X2 = N21 / N22. Formula (3): X3 = N31 / N32. N11, N21, and N31 are the number of particles of at least a predetermined particle size included per unit mass of the abrasive grains in the polishing agent, and N12, N22, and N32 are the number of particles of at least the predetermined particle size included per unit mass of the abrasive grains in an abrasive grain dispersion liquid containing the abrasive grains, a dispersant, and water.

Description

Abrasive and manufacturing method thereof, manufacturing method of additive liquid for abrasive, polishing method, and manufacturing method of semiconductor parts

[0001] The present invention relates to an abrasive and a method for producing the same, a method for producing an additive liquid for an abrasive, a polishing method, and a method for producing semiconductor components.

[0002] As semiconductor integrated circuits become more highly integrated and functional, microfabrication techniques are being developed to miniaturize and increase the density of semiconductor elements. Conventionally, in the manufacture of semiconductor integrated circuit devices (hereinafter also referred to as semiconductor devices), chemical mechanical polishing (hereinafter referred to as CMP) has been used to planarize interlayer insulating films, buried wiring, etc., in order to prevent problems such as unevenness (steps) on layer surfaces exceeding the depth of focus of lithography, making it impossible to obtain sufficient resolution. As the demand for higher definition and miniaturization of elements becomes more stringent, the importance of high planarization by CMP is increasing.

[0003] Furthermore, in the manufacture of semiconductor devices, shallow trench isolation (hereinafter referred to as STI), which uses a narrow element isolation width, has been introduced to promote further miniaturization of semiconductor elements. STI is a technique for forming an electrically isolated element region by forming a trench (groove) in a silicon substrate and filling the trench with an insulating film. An example of STI will be described with reference to FIGS. 1A and 1B . In this example, as shown in FIG. 1A , an element region of a silicon substrate 1 is first masked with a stopper film 2, and then a trench 3 is formed in the silicon substrate 1, and an insulating film such as a silicon oxide film 4 is deposited to fill the trench 3. Next, the silicon oxide film 4 on the stopper film 2, which is the protruding portion, is polished and removed by CMP while leaving the silicon oxide film 4 in the trench 3, which is the recessed portion. As shown in FIG. 1B , an element isolation structure in which the silicon oxide film 4 is filled in the trench 3 is obtained.

[0004] In CMP for STI, by increasing the selectivity (polishing rate ratio) between the silicon oxide film and the stopper film, the polishing can be stopped when the stopper film is exposed. Examples of such stopper films include nitride films and polysilicon. Polishing methods using stopper films can obtain smoother surfaces than conventional polishing methods. Furthermore, a high selectivity is required in recent CMP technology.

[0005] For example, Patent Document 1 discloses a polishing agent containing a specific anionic polymer, cerium oxide particles, and water and having a pH of 4 to 9 as a method for increasing the selectivity between a silicon dioxide film and a silicon nitride film.

[0006] JP 2019-87660 A

[0007] In the polishing agent containing the anionic polymer, when an anionic polymer having a low acid value is used, the selectivity tends to improve, but polishing scratches may increase.

[0008] In view of the above problems, the present disclosure aims to provide an abrasive that can improve selectivity while suppressing the occurrence of polishing scratches by using an anionic polymer with a low acid value. It also aims to provide a method for producing an additive liquid for an abrasive that can suitably adjust the abrasive, a polishing method using the abrasive, and a method for producing semiconductor components using the polishing method.

[0009] The present disclosure provides a polishing compound and a manufacturing method thereof, a manufacturing method of an additive liquid for a polishing compound, a polishing method, and a manufacturing method of a semiconductor component, each having the following configuration: [1] A polishing compound containing abrasive grains, an anionic polymer, and water, wherein the anionic polymer has an acid value of 400 mgKOH / g or less, and X calculated from the following formula (1): １ Abrasives having a value of 1.5 or less. １ = N １１ / N １２ ... (1) However, N １１ is the number of particles having a particle size of 0.56 μm or more contained per unit mass of abrasive grains in the abrasive; N １２is the number of particles having a particle diameter of 0.56 μm or more contained per unit mass of abrasive grains in an abrasive grain dispersion containing the abrasive grains, a dispersant, and water. [2] An abrasive grain dispersion containing abrasive grains, an anionic polymer, and water, wherein the acid value of the anionic polymer is 400 mg KOH / g or less, and X calculated from the following formula (2) ２ Abrasive having a surface roughness of 7.0 or less. ２ = N ２１ / N ２２ ... (2) However, N ２１ is the number of particles having a particle size of 0.79 μm or more contained per unit mass of abrasive grains in the abrasive; N ２２ is the number of particles having a particle diameter of 0.79 μm or more contained per unit mass of abrasive grains in an abrasive grain dispersion containing the abrasive grains, a dispersant, and water. [3] An abrasive grain dispersion containing abrasive grains, an anionic polymer, and water, wherein the acid value of the anionic polymer is 400 mg KOH / g or less, and X calculated from the following formula (3) ３ Abrasives having a value of 10 or less. ３ = N ３１ / N ３２ ... (3) However, N ３１ is the number of particles having a particle size of 0.98 μm or more contained per unit mass of abrasive grains in the abrasive; N ３２is the number of particles with a particle size of 0.98 μm or more contained per unit mass of abrasive grains in an abrasive grain dispersion containing the abrasive grains, a dispersant, and water. [4] The abrasive of any one of [1] to [3], wherein the abrasive grains contain at least one selected from the group consisting of silica particles, alumina particles, zirconia particles, cerium compound particles, titania particles, germania particles, composite particles thereof, and core-shell particles. [5] The abrasive of any one of [1] to [4], wherein the abrasive grains contain cerium compound particles. [6] The abrasive of any one of [1] to [5], wherein the abrasive grains contain ceria particles. [7] The abrasive of any one of [1] to [6], wherein the abrasive grain content is 0.01 mass % to 10.0 mass % based on the total mass of the abrasive. [8] The abrasive of any one of [1] to [7], wherein the anionic polymer is a copolymer containing a hydrophobic monomer and an anionic monomer. [9] The polishing agent of any one of [1] to [8], wherein the weight-average molecular weight of the anionic polymer is 2,000 to 50,000.

[10] The polishing agent of any one of [1] to [9], wherein the content of the anionic polymer is 0.02% by mass to 5% by mass, based on the total mass of the polishing agent.

[11] The polishing agent of any one of [1] to

[10] , further comprising a pH adjuster.

[12] The polishing agent of any one of [1] to

[11] , wherein the pH is 4 to 8.

[13] A polishing method in which a polished surface of a semiconductor substrate is brought into contact with a polishing pad while supplying an abrasive, and polishing is performed by the relative movement of the two, wherein the abrasive is the abrasive of any one of [1] to

[12] .

[14] A method for producing semiconductor components, wherein semiconductor components are obtained by singulating a semiconductor substrate having a polished surface polished by the polishing method of

[13] .

[15] A method for producing an additive liquid for an abrasive containing a salt of an anionic polymer having an acid value of 400 mgKOH / g or less, the method comprising the steps of: (1) or (2)(1) a step of dissolving an alkali metal salt of the anionic polymer in water, and (2) a step of dissolving the anionic polymer in an aqueous alkali metal hydroxide solution containing an alkali metal in an amount 1.0 times or more the number of moles of anionic groups calculated from the acid value of the anionic polymer.

[16] The method for producing an abrasive additive liquid according to

[15] , wherein the alkali metal is at least one selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium.

[17] The method for producing an abrasive according to any one of [1] to

[12] , comprising mixing abrasive grains with the abrasive additive liquid obtained by the production method according to

[15] .

[0010] According to the present disclosure, it is possible to provide a polishing agent that can improve selectivity while suppressing the occurrence of polishing scratches by using an anionic polymer with a low acid value. In addition, it is also possible to provide a method for producing an additive liquid for a polishing agent that can suitably adjust the polishing agent, a polishing method using the polishing agent, and a method for producing semiconductor components using the polishing method.

[0011] 1 is a cross-sectional view showing an example of a polishing method, the cross-sectional view showing a state of an object to be polished before polishing, a cross-sectional view showing an example of a polishing method, the cross-sectional view showing a state of an object to be polished after polishing, and a schematic view showing an example of a polishing apparatus.

[0012] Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments, and other embodiments may also fall within the scope of the present invention as long as they are consistent with the spirit of the present invention. For clarity of explanation, the following description and drawings have been simplified as appropriate. Also, for the purpose of explanation, the scale of each component in the drawings may differ significantly.

[0013] In the present invention, the term "surface to be polished" refers to the surface to be polished of the object to be polished, for example, the surface. In this specification, the term "surface to be polished" also includes intermediate surfaces that appear on semiconductor substrates in the process of manufacturing semiconductor devices. "Silicon oxide" is mainly silicon dioxide, but is not limited to this and may include silicon oxides other than silicon dioxide. "Selectivity" refers to the polishing rate (R Ａ ) the polishing rate (R Ｂ) to the ratio (R Ａ / R Ｂ "(Meth)acrylic" is a general term for "methacrylic" and "acrylic," and also includes (meth)acryloyl and (meth)acrylate. Unless otherwise specified, "to" indicating a range of values ​​includes the values ​​before and after it as the lower and upper limits.

[0014] [Abrasive] The abrasive of the present disclosure (hereinafter also referred to as the present abrasive) contains abrasive grains, an anionic polymer (hereinafter also referred to as the "specific anionic polymer") having an acid value of 400 mgKOH / g or less, and water, and is characterized by satisfying at least one of the following (I), (II), and (III): (I) X calculated from the following formula (1) １ is 1.5 or less. １ = N １１ / N １２ ... (1) However, N １１ is the number of particles having a particle size of 0.56 μm or more contained per unit mass of abrasive grains in the abrasive; N １２ is the number of particles having a particle diameter of 0.56 μm or more contained per unit mass of abrasive grains in the abrasive grain dispersion containing the abrasive grains, a dispersant, and water. ２ is 7.0 or less. ２ = N ２１ / N ２２ ... (2) However, N ２１ is the number of particles having a particle size of 0.79 μm or more contained per unit mass of abrasive grains in the abrasive; N ２２ is the number of particles having a particle diameter of 0.79 μm or more contained per unit mass of abrasive grains in the abrasive grain dispersion containing the abrasive grains, a dispersant, and water. ３ is 10 or less. X ３ = N ３１ / N ３２ ... (3) However, N ３１ is the number of particles having a particle size of 0.98 μm or more contained per unit mass of abrasive grains in the abrasive; N ３２is the number of particles with a particle size of 0.98 μm or more contained per unit mass of abrasive grains in an abrasive grain dispersion containing the abrasive grains, a dispersant, and water.

[0015] The abrasive that satisfies at least one of the above conditions (I) to (III) suppresses the generation of coarse particles and suppresses the occurrence of polishing scratches on the polished surface. Furthermore, the abrasive can select an anionic polymer with a relatively low acid value, thereby improving the selectivity. It is sufficient for the abrasive to satisfy at least one of the above conditions (I) to (III). Among these, it is preferable for the abrasive to satisfy the above condition (I), more preferable for the abrasive to satisfy the above conditions (I) and (II), and even more preferable for the abrasive to satisfy all of the above conditions (I) to (III).

[0016] <X １ How to find out > First, N １１ and N １２ and are measured by the following methods. １１ (Measuring method of (a)) Prepare the abrasive to be measured as the test liquid. The abrasive may be diluted appropriately to prepare the test liquid, taking into account the measurable range of the measuring instrument. When diluted, the diluting liquid may be water or a buffer solution, with water being preferred. Measurement is carried out using a liquid particle counter with the abrasive particles in the test liquid sufficiently dispersed. One method for confirming that the abrasive particles are sufficiently dispersed is to stir the test liquid at high speed using a mixing tumbler for 24 hours or more, and then confirm that no sediment is present at the bottom of the container. As the liquid particle counter, the AccuSizer SIS series manufactured by Entegris, etc. can be used. The measurement temperature should be within the range of 28±1°C. Abrasive concentration C in the test liquid １１ is adjusted to be in the range of 1 / 100 to 1 times the concentration recommended by the liquid particle counter. １１ The lower limit of the abrasive grain concentration C is 1 / 100,000 mass%, preferably 1 / 50,000 mass%, more preferably 1 / 20,000 mass%, and even more preferably 1 / 15,000 mass%. １１The upper limit of the abrasive grain concentration C is 1 / 10 mass%, preferably 1 / 100 mass%, more preferably 1 / 500 mass%, even more preferably 1 / 1000 mass%, even more preferably 1 / 2500 mass%, and particularly preferably 1 / 5000 mass%. １１ It is preferable to adjust the amount of particles having a particle size of 0.56 μm or more to about 1 / 12000 mass %. １１ The number of coarse particles per unit mass of abrasive grains, N １１ is the above A １１ and the mass W of the abrasive grains in the test liquid １１ (= mass of test liquid × C １１ ) to N １１ = A １１ / W １１ is calculated as follows.

[0017] (N １２ Measurement method) N １２ is the number of particles with a particle size of 0.56 μm or more per unit mass of abrasive grains in a reference abrasive grain dispersion. First, an abrasive grain dispersion is prepared. The abrasive grains used are the same as those used in the abrasive to be measured. A method known to prevent agglomeration of the abrasive grains is selected for dispersion. Abrasive grain dispersion methods include (I) a method in which the abrasive grain surfaces are coated with a polymer to disperse the abrasive grains through steric repulsion; and (II) a method in which the abrasive grains are dispersed through electrostatic repulsion by adjusting the pH of the abrasive grain dispersion and / or by surface treating the abrasive grains to a zeta potential of approximately ±40 mV. In the above method (I), an anionic polymer with an acid value exceeding 400 mg KOH / g is preferred, and polyacrylic acid, a homopolymer of acrylic acid, is more preferred. In the above method (II), the abrasive grains' zeta potential can be adjusted by adding an anionic polymer, an acidic compound, an additive, or the like; nitric acid or phosphoric acid is preferred. The zeta potential of the abrasive grains can be measured using, for example, a dynamic light scattering zeta potential measuring device (for example, DelsaNano C, manufactured by Beckman Coulter, Inc.). １１As in the measurement method of (1), the abrasive particles are sufficiently dispersed in the test liquid using a liquid particle counter. １１ The measurement temperature is set to 28±1°C. The abrasive grain concentration in the test solution is C １２ is the above C １１ In the case where the abrasive grains are ceria grains, it is more preferable to adjust the abrasive grain concentration in the abrasive grain dispersion to about 1 / 12000 mass %. The measurement is carried out in the same manner as in the test liquid using a liquid-borne particle counter, and the number A of particles having a grain size of 0.56 μm or more is １２ is obtained. N １２ is the above A １２ and the mass W of the abrasive grains in the abrasive grain dispersion liquid. １２ (= mass of abrasive dispersion liquid × C １２ ) to N １２ = A １２ / W １２ is calculated as follows.

[0018] X １ is the N measured by the above method １１ and N １２ The abrasive concentration in the test liquid is calculated using formula (1). １１ and the abrasive concentration C in the abrasive dispersion １２ If are the same, then X １ = A １１ / A １２ It may be calculated as follows. １ If the value of X is 1.5 or less, it is judged that the abrasive contains few coarse particles, and the abrasive can suppress polishing scratches. １ is preferably 1.2 or less, more preferably 1.0 or less, and even more preferably 0.8 or less.

[0019] <X ２ and X ３ How to find X ２ is N ２１ and N ２２ From the measured values ​​of X ３ is N ３１ and N ３２ are calculated from the measured values ​​of N by equations (2) and (3), respectively. ２１ and N ３１ is the above N１１ The number A of particles with a particle size of 0.79 μm or more was measured using the same method as in ２１ , the number A of particles having a particle size of 0.98 μm or more ３１ Just count each of them. １１ , A ２１ and A ３１ may be simultaneously determined by one measurement. ２２ and N ３２ is the above N １２ The number A of particles with a particle size of 0.79 μm or more was measured using the same method as in ２２ , the number A of particles having a particle size of 0.98 μm or more ３２ Just count each of them. １２ , A ２２ and A ３２ may be simultaneously determined by one measurement. ２ If the value is 7.0 or less, it is judged that the abrasive contains few coarse particles, and the abrasive can suppress polishing scratches. ２ is preferably 5.0 or less, more preferably 2.0 or less, even more preferably 1.8 or less, and particularly preferably 1.5 or less. ３ If the value is 10 or less, it is judged that the abrasive contains few coarse particles, and the abrasive can suppress polishing scratches. ３ is preferably 8.0 or less, more preferably 5.0 or less, even more preferably 4.5 or less, and particularly preferably 4.0 or less.

[0020] Next, each component that can be contained in the present abrasive will be described. <Abrasive Grains> In the present abrasive, the abrasive grains can be appropriately selected from those used as abrasive grains for CMP. Examples of the abrasive grains include at least one selected from the group consisting of silica particles, alumina particles, zirconia particles, cerium compound particles (e.g., ceria particles, cerium hydroxide particles), titania particles, germania particles, and core-shell particles having these as core particles. Examples of the silica particles include colloidal silica and fumed silica. Colloidal alumina can also be used as the alumina particles.

[0021] The core-shell particles are composed of a core particle (e.g., silica particle, alumina particle, zirconia particle, cerium compound particle, titania particle, or germania particle) and a thin film covering the surface of the core particle. The thin film may be made of at least one oxide selected from the group consisting of silica, alumina, zirconia, ceria, titania, germania, iron oxide, manganese oxide, zinc oxide, yttrium oxide, calcium oxide, magnesium oxide, lanthanum oxide, and strontium oxide. The thin film may also be composed of a plurality of nanoparticles made of these oxides.

[0022] The particle size of the core particle is preferably 0.01 μm to 0.5 μm, more preferably 0.03 μm to 0.3 μm. The particle size of the nanoparticles is only required to be smaller than the particle size of the core particle, and is preferably 1 nm to 100 nm, more preferably 5 nm to 80 nm.

[0023] Among the above-mentioned abrasive grains, silica particles, alumina particles, or cerium compound particles are preferred because of their excellent insulating film removal rate, and cerium compound particles are more preferred. When the surface to be polished contains an insulating film (particularly a silicon oxide film), ceria particles are even more preferred because of their high removal rate. In the case of core-shell type particles, the thin film preferably contains silica, alumina, or a cerium compound, and more preferably contains ceria. One type of abrasive grain can be used alone, or two or more types can be used in combination.

[0024] The content of ceria relative to the total mass of the abrasive grains is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass. If the content of ceria relative to the total mass of the abrasive grains is 70% by mass or more, the polishing rate, particularly for insulating films, is easily improved.

[0025] The ceria particles can be appropriately selected from known ones and include, for example, ceria particles produced by the methods described in JP-A-11-12561, JP-A-2001-35818, and JP-A-2010-505735. Specific examples include ceria particles obtained by adding an alkali to an aqueous ammonia solution of cerium (IV) nitrate to produce a cerium hydroxide gel, which is then filtered, washed, and fired; ceria particles obtained by crushing high-purity cerium carbonate, then crushing and classifying it; and ceria particles obtained by chemically oxidizing a cerium (III) salt in a liquid.

[0026] Although the ceria particles may contain impurities other than ceria, the content of ceria in one ceria particle is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and most preferably 100% by mass (without impurities). If the content of ceria in the ceria particles is 80% by mass or more, the polishing rate of the insulating film is likely to be improved.

[0027] The average particle size of the abrasive grains is preferably 0.01 μm to 0.5 μm, and more preferably 0.03 μm to 0.3 μm. If the average particle size is 0.5 μm or less, the mechanical action on the polished surface is reduced, thereby suppressing the occurrence of polishing flaws such as scratches on the polished surface. Furthermore, if the average particle size is 0.01 μm or more, aggregation of the abrasive grains is suppressed, resulting in excellent storage stability of the abrasive and excellent polishing rate.

[0028] The above particle size refers to the particle size of primary particles when the abrasive grains are dispersed in the liquid without agglomeration. The above particle size refers to the particle size of agglomerated particles (secondary particles) when the abrasive grains are aggregated in the liquid. In either case, the average particle size is measured using a particle size distribution analyzer such as a laser diffraction / scattering type, using a dispersion liquid in which the abrasive grains are dispersed in a dispersing medium such as pure water.

[0029] The lower limit of the abrasive grain content is preferably 0.01 mass%, more preferably 0.05 mass%, even more preferably 0.1 mass%, even more preferably 0.2 mass%, and particularly preferably 0.3 mass%, relative to the total mass of the abrasive. If the abrasive grain content is equal to or greater than the above lower limit, an excellent polishing rate for the surface to be polished can be obtained. On the other hand, the upper limit of the abrasive grain content is preferably 10.0 mass%, more preferably 8.0 mass%, even more preferably 5.0 mass%, particularly preferably 2.0 mass%, particularly more preferably 1.0 mass%, extremely preferably 0.8 mass%, and most preferably 0.5 mass% relative to the total mass of the abrasive. If the abrasive grain content is equal to or less than the above upper limit, aggregation of the abrasive grains can be suppressed, and an increase in the viscosity of the abrasive can be suppressed, resulting in excellent handleability.

[0030] <Anionic Polymer> In the present polishing compound, the anionic polymer can be appropriately selected from those having an acid value of 400 mg KOH / g or less. By using this specific anionic polymer, polishing of the stopper film is suppressed while maintaining a high polishing rate for the silicon oxide film, a high selectivity between the silicon oxide film and the stopper film can be obtained, and polishing with high flatness can be achieved. The stopper film can be, for example, a compound containing one or more selected from silicon, carbon, hafnium, zirconium, cobalt, ruthenium, molybdenum, titanium, tantalum, and copper, or a nitride or oxide containing one or more of these. More specifically, metal elements such as copper, cobalt, ruthenium, molybdenum, titanium, and tantalum can be used. Nitrides such as titanium nitride, tantalum nitride, and silicon nitride can be used. Oxides such as zirconia and hafnium oxide can be used. Polysilicon, amorphous silicon, hafnium silicate, zirconium silicate, and silicon carbide can be used. Among these, silicon nitride and polysilicon are preferred because of their higher selectivity.

[0031] The specific anionic polymer is preferably a copolymer containing a hydrophobic monomer and an anionic monomer, in order to obtain a higher selectivity. The constitution of the copolymer anionic polymer will be described below.

[0032] (Hydrophobic Monomer) In the present disclosure, a hydrophobic monomer refers to a monomer whose solubility in 100 g of water at 20° C. (hereinafter also referred to as "solubility") is 10 g or less. When the anionic polymer has a hydrophobic block derived from the hydrophobic monomer, polishing of the stopper film is further suppressed. In terms of hydrophobic interactions between anionic polymers, the solubility is preferably 7 g or less, more preferably 5 g or less, even more preferably 3 g or less, and particularly preferably 2 g or less.

[0033] As the hydrophobic monomer, a monomer having no ionic group or hydrophilic group is preferred, and a compound represented by the following formula (4) is more preferred. However, R １ is a hydrogen atom or a methyl group, R １１ represents a hydrocarbon group which may have O or Si between carbon atoms and in which a hydrogen atom may be substituted with a halogen atom, and L １ is a single bond or a divalent linking group.

[0034] In the above formula (4), R １１ is a substituent that exhibits hydrophobicity, and is a hydrocarbon group that may have O or Si between carbon atoms and in which a hydrogen atom may be substituted with a halogen atom. １１Examples of the hydrocarbon group in (I) include an alkyl group, an aryl group, and an aralkyl group. The alkyl group may be linear, branched, or cyclic. The alkyl group preferably has 1 to 18 carbon atoms, and more preferably 1 to 12 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a cyclododecyl group, a bornyl group, and an adamantyl group. Examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a tolyl group, and a xylyl group. The aryl group preferably has 6 to 24 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aralkyl group include a benzyl group, a phenethyl group, a naphthylmethyl group, and a biphenylmethyl group. The number of carbon atoms in the aralkyl group is preferably 7 to 20, and more preferably 7 to 14. １１ When R has an aromatic ring, the hydrogen atom of the aromatic ring may have a substituent such as a linear or branched alkyl group having 1 to 4 carbon atoms. １１ The hydrocarbon group in the formula (I) may further have O or Si between carbon atoms, and a hydrogen atom may be substituted with a halogen atom. Examples of the hydrocarbon group having O or Si between carbon atoms include -(CH ２ CH ２ O) ｘ -, -(CH ２ O) ｘ - and alkylene oxides such as -CH ２ Si(R １２ ) ２ -CH ２ Here, x represents the number of repeating units, and is preferably an integer of 1 to 18. １２ are each independently a hydrogen atom or a methyl group. １１ The hydrogen atoms of the hydrocarbon groups in the above structures may be substituted with halogen atoms. Examples of halogen atoms include F, Cl, Br, and I. １１is preferably a hydrocarbon group that does not contain O, Si, or halogen atoms, from the viewpoint of hydrophobicity and availability.

[0035] L １ is an unsaturated double bond and R １１ is a single bond or a divalent linking group connecting １ Examples of the alkylene group include alkylene groups having 1 to 8 carbon atoms, -(CH ２ CH ２ O) ｘ -, -(CH ２ O) ｘ -, -CONH-, -COO-, -C(=O)-, etc. Examples of the alkylene group having 1 to 8 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. １ is preferably a single bond, —CONH—, or —COO— because of ease of availability.

[0036] The hydrophobic monomer may be used alone or in combination of two or more. From the viewpoint of dispersibility in the abrasive, the hydrophobic monomer may be a combination of a monomer having a ring structure and a monomer not having a ring structure.

[0037] Specific examples of hydrophobic monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-dodecyl (meth)acrylate, and stearyl (meth)acrylate; (meth)acrylates having a ring structure such as 1-methylcyclopentyl acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate; Examples of the alkyl (meth)acrylate include (meth)acrylamide, (meth)acrylamide derivatives such as N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dibutyl (meth)acrylamide, N-tert-butyl acrylamide, N-phenyl (meth)acrylamide, and N-benzyl (meth)acrylamide; and vinyl monomers such as styrene, methyl styrene, vinyl toluene, p-t-butyl styrene, chloromethyl styrene, vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride. Among the above, alkyl (meth)acrylate or styrene is preferred, and as the alkyl (meth)acrylate, an alkyl (meth)acrylate having an alkyl group having 1 to 6 carbon atoms is more preferred.

[0038] (Anionic Monomer) An anionic monomer is a monomer having an anionic group or a salt thereof. The anionic group is strongly adsorbed to the stopper film and acts as a protective film for the stopper film. Examples of the anionic monomer include compounds having an unsaturated bond and an anionic group. Examples of the anionic group include a carboxy group (—COOH), a sulfo group (—SO ３Examples of anionic groups include phosphonic acid (-P(-OH)(-OR)(=O)), phosphate ester (-OP(-OH)(-OR)(=O)), phenolic hydroxyl group, and salts thereof. Hereinafter, R represents a hydrogen atom or an alkyl group. Hereinafter, anionic groups and salts thereof may be collectively referred to as "anionic groups, etc."

[0039] In view of the interaction with the stopper film, the anionic monomer preferably contains a compound represented by the following formula (5). However, R ２ , R ３ , R ４ and R ５ are each independently a hydrogen atom, a hydrocarbon group, or a group having an anionic group or a salt thereof, and R ２ ~R ５ At least one of the groups is an anionic group or a group having a salt thereof, and when the molecule has two or more carboxy groups, the carboxy groups may form an anhydride.

[0040] R ２ ~R ５ Examples of the hydrocarbon group in R include an alkyl group, an aryl group, and an aralkyl group. Specific examples of the alkyl group, the aryl group, and the aralkyl group are those shown in the above R １１ In this polishing compound, in view of the interaction between the anionic group and the stopper film, R ２ ~R ５ The hydrocarbon group in is preferably an alkyl group having 1 to 6 carbon atoms, and among these, a methyl group or an ethyl group is preferred, with a methyl group being more preferred.

[0041] R ２ ~R ５ The group having an anionic group or the like in ２ -R ２１ It is preferable that the compound has the structure: ２ is an unsaturated double bond and R ２１ is a single bond or a divalent linking group connecting ２ Examples of the alkylene group include an alkylene group having 1 to 8 carbon atoms, a phenylene group, and —(CH ２ CH ２ O) ｘ -R２２ -, -(CH ２ O) ｘ -R ２２ --, --CONH-R ２２ -, -COO-R ２２ -, etc., where x is an integer of 1 to 18, and R ２２ is preferably a single bond or an alkylene group having 1 to 8 carbon atoms. ２ and R ２２ Examples of the alkylene group in L include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group, and each may have a halogen atom as a substituent. ２ is a single bond, -CONH-R, from the viewpoint of ease of availability of monomers. ２２ -, or -COO-R ２２ - is preferred.

[0042] R ２１ R is a carboxy group, a sulfo group, a phosphate ester, a phosphonic acid, a hydroxyphenyl group, or a salt thereof. When the anionic group is a salt, examples of the counter cation include an alkali metal ion, an alkaline earth metal ion, and an ammonium ion. Among these, an alkali metal ion or an ammonium ion is preferred, a sodium ion, a potassium ion, or an ammonium ion is more preferred, and a sodium ion or a potassium ion is even more preferred. ２１ In terms of the stability of the polymer and the protection of the stopper film, the anionic group in the formula (I) is preferably a carboxy group, a sulfo group or a salt thereof, and more preferably a carboxy group or a salt thereof.

[0043] The number of anionic groups in one molecule of the anionic monomer may be 1 or more, and from the viewpoint of polymerizability of the polymer, it is preferably 1 to 2. When the molecule has two carboxy groups, the carboxy groups may be in the form of anhydrides.

[0044] In formula (5), R ２ ~R ５ A preferred combination of (I) R ２ is a group having an anionic group or the like, R ３ ~R ５are each independently a hydrogen atom or a combination of hydrocarbon groups; (II) R ２ and R ３ is a group having an anionic group or the like, R ４ and R ５ are each independently a hydrogen atom or a combination of hydrocarbon groups; (III) R ２ and R ５ is a group having an anionic group or the like, R ３ and R ４ are each independently a hydrogen atom or a hydrocarbon group; etc. In (I) to (III), the hydrocarbon group is preferably a methyl group. In (II) and (III), the anionic group is preferably a carboxy group.

[0045] Specific examples of the anionic monomer include (meth)acrylic acid, vinyl benzoic acid, 2-carboxyethyl (meth)acrylate, allyl sulfonic acid, methallylsulfonic acid, 2-(meth)acryloyloxyethyl acid phosphate, maleic acid (maleic anhydride), fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and salts thereof. Among these, from the viewpoint of polymerizability, (meth)acrylic acid, maleic acid, itaconic acid, fumaric acid, and salts thereof are preferred, and (meth)acrylic acid, maleic acid, and salts thereof are more preferred. The anionic monomers can be used alone or in combination of two or more.

[0046] (Physical Properties of Anionic Polymer) In this polishing compound, the anionic polymer has an acid value of 400 mgKOH / g or less. The use of this specific anionic polymer improves the selectivity between the silicon oxide film and the stopper film. The upper limit of the acid value of the specific anionic polymer is preferably 350 mgKOH / g, more preferably 300 mgKOH / g, and even more preferably 280 mgKOH / g, from the viewpoint of improving the selectivity. The lower limit of the acid value of the specific anionic polymer is preferably 20 mgKOH / g or more, more preferably 50 mgKOH / g, even more preferably 100 mgKOH / g, and particularly preferably 150 mgKOH / g, from the viewpoint of suppressing abrasive grain aggregation. The acid value represents the mass (mg) of potassium hydroxide required to neutralize the acidic components contained in 1 g of the solid content of the polymer, and is a value measured by the method described in JIS K 0070:1992.

[0047] In the specific anionic polymer, the ratio of the hydrophobic monomer to the anionic monomer may be appropriately adjusted so that the acid value falls within the above range. For example, the ratio of the hydrophobic monomer is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 40 mol% or more, based on the total of all monomers constituting the specific anionic polymer. By adjusting the hydrophobic monomer to 10 mol% or more, polishing of the stopper film can be further suppressed. Furthermore, in the specific anionic polymer, the ratio of the hydrophobic monomer is preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less, and particularly preferably 80 mol% or less, based on the total of all monomers. By adjusting the hydrophobic polymer to 95 mol% or less, the solubility of the specific anionic polymer is improved, and aggregation of abrasive grains and aggregation of the specific anionic polymer are suppressed.

[0048] The specific anionic polymer may be a random polymer in which the hydrophobic monomers and the anionic monomers are randomly arranged, or may be a block polymer having a block of anionic monomers and a block of anionic monomers.

[0049] The solubility of the specific anionic polymer in water is 5 mg / 100 g-H at 25° C. in view of storage stability and the like. ２ Preferably 0 or more, 10 mg / 100 g-H ２ O or more is more preferable.

[0050] The weight average molecular weight Mw of the specific anionic polymer is preferably 1,000 to 100,000 from the viewpoint of dispersion stability of the specific anionic polymer. The lower limit of the weight average molecular weight Mw of the specific anionic polymer is preferably 2,000, more preferably 4,000, and even more preferably 6,000. The upper limit of the weight average molecular weight Mw of the specific anionic polymer is preferably 50,000, more preferably 40,000, even more preferably 30,000, even more preferably 25,000, particularly preferably 20,000, and extremely preferably 17,500. The weight average molecular weight (Mw) is determined by gel permeation chromatography (GPC) as a value converted into standard polystyrene.

[0051] The specific anionic polymer may be a commercially available product or may be synthesized. For example, in the case of a random polymer, a hydrophobic monomer and an anionic monomer are mixed, and an initiator is further added, followed by polymerization by a known polymerization method such as solution polymerization, bulk polymerization, or various radical polymerizations. Among these, solution polymerization is preferred because it is easy to adjust the weight-average molecular weight of the copolymer. In the case of a block polymer, for example, an anionic block may be synthesized first, and then a hydrophobic monomer may be polymerized onto the anionic block. In the production method, the order of polymerization of the anionic block and the hydrophobic block may be reversed. Alternatively, the anionic block and the hydrophobic block may be synthesized separately, and then the anionic block and the hydrophobic block may be coupled.

[0052] From the viewpoint of the effect of suppressing polishing of the stopper film, the content of the specific anionic polymer is preferably 0.02 mass % to 0.5 mass %, more preferably 0.05 mass % to 0.45 mass %, even more preferably 0.08 mass % to 0.4 mass %, and particularly preferably 0.1 mass % to 0.35 mass %, relative to the total mass of the abrasive.

[0053] <Water> The polishing compound contains water as a medium for dispersing abrasive grains. The type of water is not particularly limited, but it is preferable to use pure water, ultrapure water, ion-exchanged water, etc., taking into consideration the effects on other components, prevention of impurity contamination, and effects on pH, etc.

[0054] <Additives> The present abrasive may further contain various additives. Examples of such additives include pH adjusters, dispersants, nonionic polymers, anti-flocculants, lubricants, viscosity imparting agents, viscosity modifiers, and preservatives, and the abrasive may contain two or more types of additives.

[0055] (pH Adjusting Agent) A pH adjusting agent may be contained to adjust the pH to a predetermined value. The pH adjusting agent may be appropriately selected from acidic compounds, basic compounds, amphoteric compounds such as amino acids, and salts thereof.

[0056] Examples of acidic compounds include inorganic acids, organic acids, and salts thereof. Examples of inorganic acids include nitric acid, sulfuric acid, hydrochloric acid, and phosphoric acid, and ammonium salts, sodium salts, potassium salts, and the like of these may also be used. Examples of organic acids include compounds having a carboxy group, sulfo group, or phospho group as an anionic group, and ammonium salts, sodium salts, potassium salts, and the like of these.

[0057] Examples of organic acids having a carboxy group include alkyl monocarboxylic acids such as formic acid, acetic acid, and propionic acid; carboxylic acids having a heterocycle such as 2-pyridinecarboxylic acid, 3-pyridinecarboxylic acid, 4-pyridinecarboxylic acid, 2,3-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 2,5-pyridinedicarboxylic acid, 2,6-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, pyrazinecarboxylic acid, 2,3-pyrazinedicarboxylic acid, 2-quinolinecarboxylic acid, pyroglutamic acid, picolinic acid, DL-pipecolic acid, 2-furancarboxylic acid, 3-furancarboxylic acid, tetrahydrofuran-2-carboxylic acid, and tetrahydrofuran-2,3,4,5-tetracarboxylic acid; and carboxylic acids having an alicyclic ring such as cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cycloheptanecarboxylic acid, and cyclohexylcarboxylic acid. Carboxylic acids having an amino group, such as alanine, glycine, glycylglycine, aminobutyric acid, N-acetylglycine, N,N-di(2-hydroxyethyl)glycine, N-(tert-butoxycarbonyl)glycine, proline, trans-4-hydroxy-L-proline, phenylalanine, sarcosine, hydantoic acid, creatine, N-[tris(hydroxymethyl)methyl]glycine, glutamic acid, and aspartic acid; carboxylic acids having a hydroxyl group, such as lactic acid, malic acid, citric acid, tartaric acid, glycolic acid, gluconic acid, salicylic acid, 2-hydroxyisobutyric acid, glyceric acid, 2,2-bis(hydroxymethyl)propionic acid, and 2,2-bis(hydroxymethyl)butyric acid; carboxylic acids having a ketone group (keto acids), such as pyruvic acid, acetoacetic acid, and levulinic acid; Dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, and phthalic acid;

[0058] Examples of basic compounds include ammonia, sodium hydroxide, potassium hydroxide, ammonium hydroxide, potassium carbonate, sodium carbonate, ammonium carbonate; quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and amino alcohols such as monoethanolamine, diethanolamine, and triethanolamine. Examples of amphoteric compounds include glycine, alanine, and phenylalanine.

[0059] The pH adjuster can be used alone or in combination of two or more. The pH of the polishing compound is preferably 4 to 8 in order to suppress agglomeration of the abrasive grains and further improve the selectivity. The pH adjuster may be appropriately adjusted to achieve the above pH. For example, the pH adjuster may be present in an amount of 0.005 to 2.0% by mass, preferably 0.01 to 1.5% by mass, and more preferably 0.01 to 0.3% by mass, based on the total amount of the polishing compound.

[0060] (Dispersant) The abrasive may contain a dispersant to improve the dispersibility of the abrasive grains. Examples of dispersants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, and one or more of these can be used. Anionic surfactants are preferably polymers having a carboxy group or an ammonium carboxylate salt, and polyacrylic acid or a polyacrylate is preferred. Examples of cationic surfactants include diallyldimethylammonium chloride polymers, diallyldimethylammonium chloride-sulfur dioxide copolymers, diallyldimethylammonium chloride-acrylamide copolymers, diallyldimethylammonium chloride-maleic acid copolymers, and maleic acid-diallyldimethylammonium ethyl sulfate-sulfur dioxide copolymers. The weight-average molecular weight of the surfactant is preferably 10,000 to 100,000, from the viewpoint of polishing the surface to be polished at a higher speed.

[0061] When a dispersant is used, the content thereof is preferably 0.0001% by mass to 0.3% by mass, more preferably 0.001% by mass to 0.2% by mass, and even more preferably 0.01% by mass to 0.15% by mass, relative to the total mass of the abrasive, from the viewpoint of polishing the surface to be polished at a higher speed.

[0062] (Nonionic Polymer) The present abrasive may also contain a nonionic polymer. From the viewpoint of lubricity, the nonionic polymer is preferably a nonionic polymer having an ether bond, and more preferably a nonionic polymer containing an ether bond in the main chain. Specific examples of nonionic polymers include polyethylene glycol, polyglycerin, and water-soluble nylon. When a nonionic polymer is used, its content can be 0.005% by mass to 2.0% by mass, preferably 0.01% by mass to 1.5% by mass, and more preferably 0.01% by mass to 0.3% by mass, based on the total mass of the present abrasive. If the content of the nonionic polymer is within the above range, the wettability of the abrasive with respect to the polished surface is improved, increasing the contact frequency of the abrasive grains, and therefore improving the removal rate of the silicon oxide film.

[0063] When the above-mentioned additives are used in the present polishing agent, the total content of the additives is preferably 0.01 mass % to 10.0 mass %, and more preferably 0.01 mass % to 5.0 mass %, relative to the total mass of the polishing agent, in order to obtain a polishing agent having a high selectivity between the silicon oxide film and the stopper film.

[0064] [Method of Manufacturing the Abrasive] The abrasive is manufactured by the method of manufacturing the abrasive using the specific anionic polymer. １ ~X ３ is adjusted so that it is lower than a predetermined value. １ ~X ３The method for reducing the specific anionic polymer is not particularly limited, but examples include converting at least a portion of the anionic groups of the specific anionic polymer into alkali metal salts when dissolving the specific anionic polymer. The mechanism by which the use of alkali metal salts of the specific anionic polymer suppresses coarse particles remains unclear, but is presumed to be as follows: Compared to ammonium salts of the specific anionic polymer, alkali metal salts of the specific anionic polymer suppress intramolecular aggregation. It is presumed that ammonium ions and the like adsorb to multiple anionic groups within the polymer and aggregate. In contrast, alkali metal salts are presumed to strongly adsorb to a single anionic group, suppressing aggregation of the anionic groups. Therefore, even when an anionic polymer with a low acid value is used, it is presumed that the anionic groups efficiently interact with the abrasive grains, suppressing aggregation (coarsening of the abrasive grains). As shown in the examples below, this effect was observed to be maintained even when cation exchange was performed to convert the specific anionic polymer to an ammonium salt after dissolution. From the above, it is presumed that by converting at least a portion of the anionic groups into alkali metal salts when dissolving the specific anionic polymer, coarsening of the abrasive grains can be suppressed.

[0065] Specific examples of methods for dissolving specific anionic polymers include those comprising the following steps (1) or (2): (1) dissolving a specific anionic polymer whose anionic groups are alkali metal salts in water; and (2) dissolving the specific anionic polymer in an alkali metal hydroxide aqueous solution containing alkali metals in an amount 1.0 times, preferably 1.1 times or more, the molar amount of the anionic groups calculated from the acid value of the specific anionic polymer. In steps (1) or (2), the aqueous solution may be heated as needed to facilitate dissolution of the specific anionic polymer. Alternatively, the aqueous solution of anionic polymer alkali metal salt obtained in steps (1) or (2) may be subjected to ion exchange with ammonium ions or amine ions after removing alkali metal ions using an ion exchange membrane. This method is preferred because it can suppress metal contamination when manufacturing semiconductor components using this polishing compound. Examples of alkali metals include lithium, sodium, potassium, rubidium, and cesium, with sodium or potassium being preferred in terms of suppressing coarsening of abrasive grains.

[0066] In consideration of the above-mentioned method for dissolving the specific anionic polymer, the method for producing an abrasive is preferably, specifically, (A) a method of preparing a dispersion of abrasive grains and an aqueous solution of the specific anionic polymer (hereinafter also referred to as "abrasive additive liquid") and mixing them; or (B) a method of preparing abrasive grains, the specific anionic polymer, water or an aqueous alkali metal hydroxide solution, and additives used as needed and mixing them. The abrasive additive liquid in (A) can be prepared by the above-mentioned steps (1) or (2) in the above-mentioned method for dissolving the specific anionic polymer. In the above-mentioned method (B), when an aqueous alkali metal hydroxide solution is used, the amount of alkali metal is the same as in the above-mentioned step (2) in the above-mentioned method for dissolving the specific anionic polymer.

[0067] The method (A) is preferred in terms of the excellent storage stability and ease of transportation of the abrasive dispersion and the additive liquid for the abrasive. The method (A) can also be applied inside the polishing machine when the abrasive is used.

[0068] In addition, when the abrasive is prepared by mixing two liquids, an abrasive dispersion and an abrasive additive, the abrasive concentration in the dispersion and the anionic polymer and acidic compound in the abrasive additive may be concentrated 2 to 100 times higher than when the abrasive is used, and then diluted to the desired concentration when used. More specifically, for example, if the abrasive concentration in the dispersion and the anionic polymer and acidic compound in the additive are both concentrated 10 times, the abrasive is prepared by mixing and stirring 10 parts by mass of the dispersion, 10 parts by mass of the abrasive additive, and 80 parts by mass of water. By adding the above-mentioned abrasive additive to the abrasive dispersion, coarsening of the abrasive grains is suppressed, and polishing scratches can be suppressed while maintaining a high polishing rate for the silicon oxide film.

[0069] In the above-mentioned additive liquid for abrasives, the content (concentration) of the anionic polymer is preferably 0.001 to 30 mass %, more preferably 0.01 to 20 mass %, and even more preferably 0.1 to 10 mass %, of the total additive liquid for abrasives. In the above-mentioned dispersion liquid of abrasive grains, the content (concentration) of the abrasive grains is preferably 0.2 to 40 mass %, more preferably 1 to 20 mass %, and even more preferably 5 to 10 mass %.

[0070] [Polishing Method] The polishing method according to the present invention is a polishing method in which a polishing surface containing silicon oxide of a semiconductor substrate is polished by bringing a polishing pad into contact with the surface to be polished while supplying an abrasive, and polishing is performed by the relative movement of the two. The abrasive according to the present invention is used as the abrasive.

[0071] Examples of the surface to be polished include a surface of a semiconductor substrate made of silicon dioxide, a blanket wafer in which a stopper film and a silicon oxide film are laminated on the surface of a semiconductor substrate, and a patterned wafer in which these film types are arranged in a pattern. A preferred example of the semiconductor substrate is a substrate for STI. The abrasive of the present invention is also effective for polishing to planarize an interlayer insulating film between multilayer wiring in the manufacture of semiconductor devices.

[0072] Examples of silicon oxide films in STI substrates include so-called PE-TEOS films formed by plasma CVD using tetraethoxysilane (TEOS) as a raw material. Examples of silicon oxide films include so-called HDP films formed by high-density plasma CVD. Other examples include HARP films and FCVD films formed by other CVD methods, and SOD films formed by spin coating. Examples of silicon nitride films include those formed by low-pressure CVD or plasma CVD using silane or dichlorosilane and ammonia as raw materials, or those formed by ALD. Examples of polysilicon films include those formed by low-pressure CVD or plasma CVD using silane as a raw material, and then heat-treated to form polycrystalline granules.

[0073] A known polishing apparatus can be used for this polishing method. Fig. 2 is a schematic diagram showing an example of a polishing apparatus. The polishing apparatus 20 shown in Fig. 2 includes a polishing head 22 that holds a semiconductor substrate 21 such as an STI substrate, a polishing platen 23, a polishing pad 24 attached to the surface of the polishing platen 23, and an abrasive supply pipe 26 that supplies an abrasive 25 to the polishing pad 24. While the abrasive 25 is supplied from the abrasive supply pipe 26, the polished surface of the semiconductor substrate 21 held by the polishing head 22 is brought into contact with the polishing pad 24, and the polishing head 22 and the polishing platen 23 are rotated relative to each other to perform polishing.

[0074] The polishing head 22 may move linearly as well as rotaryly. Furthermore, the polishing platen 23 and polishing pad 24 may be approximately the same size as or smaller than the semiconductor substrate 21. In this case, it is preferable to move the polishing head 22 and polishing platen 23 relative to each other so that the entire surface to be polished of the semiconductor substrate 21 can be polished. Furthermore, the polishing platen 23 and polishing pad 24 do not have to be of the type that moves rotary, and may be, for example, of the type that moves in one direction as a belt.

[0075] Although there are no particular limitations on the polishing conditions for such a polishing apparatus 20, applying a load to the polishing head 22 to press it against the polishing pad 24 can increase the polishing pressure and improve the polishing rate. The polishing pressure is preferably about 0.5 to 50 kPa, and more preferably about 3 to 40 kPa from the viewpoints of uniformity of the polishing rate across the polished surface of the semiconductor substrate 21, flatness, and prevention of polishing defects such as scratches. The rotation speed of the polishing platen 23 and the polishing head 22 is preferably about 50 to 500 rpm. The supply amount of the abrasive 25 is appropriately adjusted depending on the composition of the abrasive, the above-mentioned polishing conditions, etc.

[0076] The polishing pad 24 can be made of a material such as nonwoven fabric, polyurethane foam, porous resin, or non-porous resin. To facilitate the supply of abrasive 25 to the polishing pad 24 or to allow a constant amount of abrasive 25 to accumulate on the polishing pad 24, the surface of the polishing pad 24 may be grooved in a grid, concentric circle, spiral, or other pattern. If necessary, a pad conditioner may be brought into contact with the surface of the polishing pad 24 to condition the surface of the polishing pad 24 while polishing.

[0077] According to this polishing method, a high selectivity between the silicon oxide film and the stopper film can be obtained while suppressing polishing scratches, and highly flat polishing can be achieved.

[0078] [Method for Manufacturing Semiconductor Components] The method for manufacturing semiconductor components according to this embodiment is to obtain semiconductor components by dicing a semiconductor substrate having a surface to be polished that has been polished by the polishing method according to the present invention.

[0079] The method for manufacturing a semiconductor component of the present disclosure includes a singulation step of singulating a semiconductor substrate having a polished surface polished by the polishing method. The singulation step may include, for example, dicing the semiconductor substrate (e.g., a semiconductor wafer) using a known method such as blade dicing, laser dicing, or plasma dicing to obtain semiconductor chips as semiconductor components. The method for manufacturing a semiconductor component of the present disclosure may further include a bonding step of bonding another member to the polished surface of the semiconductor chip. This step results in a semiconductor component as a bonded assembly. Examples of the other member include a second semiconductor chip, a rewiring layer, etc. The second semiconductor chip may be a semiconductor chip obtained by the manufacturing method of the present disclosure, or may be a semiconductor chip obtained by another method. The bonding step may include, for example, placing another member directly on the polished surface and bonding it directly by fusion bonding, surface activated bonding, or the like, or bonding the polished surface to the other member via an adhesive layer. Examples of the adhesive layer include a metal layer such as solder or copper, a glass layer, or a resin layer such as polyimide or epoxy. The present disclosure can further provide an electronic device including at least one semiconductor component having a surface polished by the polishing method of the present disclosure.

[0080] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Examples 1 to 4 are examples, and Examples 5 to 9 are comparative examples.

[0081] [Measurement Method] <pH> The pH was measured using a pH meter HM-30R manufactured by DKK-TOA Corporation, with the temperature set to 25±5°C.

[0082] <Average particle size> The average particle size was measured using a laser scattering / diffraction particle size distribution measuring device (manufactured by Horiba, Ltd., device name: LA-950).

[0083] <Acid value> The acid value was measured according to the method described in JIS K 0070:1992.

[0084] <Weight-average molecular weight (Mw)> Measured by gel permeation chromatography (GPC) under the following conditions: Apparatus: HLC-8320GPC (manufactured by Tosoh Corporation) Column: TSKgel GMPWXL (manufactured by Tosoh Corporation) Detector: RI detector, polarity (+) Eluent: 0.2 M NaNO ３ Aqueous solution Flow rate: 1.0 mL / min Column temperature: 40°C Calculated using standard PEO / PEG

[0085] <X １ ~X ３ > Each abrasive was diluted with water to an abrasive concentration of approximately 1 / 12,000% by mass to prepare a test solution, and the number of particles with a particle size of 0.56 μm or more, the number of particles with a particle size of 0.79 μm or more, and the number of particles with a particle size of 0.98 μm or more were measured using the method described above. Furthermore, a reference abrasive dispersion was prepared using polyacrylic acid as a dispersant, and the abrasive concentration was adjusted to approximately 1 / 12,000% by mass, and the number of particles with a particle size of 0.56 μm or more, the number of particles with a particle size of 0.79 μm or more, and the number of particles with a particle size of 0.98 μm or more were measured using the same method described above. A particle counter (AccuSizer series manufactured by Entegris) was used as the measuring device, and measurements were made at a temperature range of 28±1°C.

[0086] [Abrasive Dispersion] Ceria particles having an average particle size of 100 nm and a ceria content of 95% by mass or more were used as abrasive particles. The ceria particles were dispersed in water to prepare an abrasive dispersion containing 0.33% by mass of ceria particles.

[0087] [Abrasive Additive] Example 1 A styrene / maleic acid copolymer (weight average molecular weight 8,000, acid value 350 mg KOH / g, styrene to maleic acid molar ratio 2:1) was dissolved in an aqueous potassium hydroxide solution containing potassium hydroxide in an amount 1.1 times or more the number of moles of anionic groups calculated from the acid value, while heating to 60°C. Subsequently, the styrene-maleic acid copolymer potassium salt was subjected to cation exchange using an ion exchange membrane to obtain an aqueous styrene / maleic acid copolymer ammonium salt solution. Water and a pH adjuster were then added to adjust the pH to 5.5, yielding an abrasive additive containing 0.2 mass% of styrene / maleic acid copolymer ammonium salt.

[0088] Example 2 A styrene / maleic acid copolymer (weight average molecular weight 10,000, acid value 275 mg KOH / g, molar ratio of styrene to maleic acid 3:1) was dissolved in an aqueous potassium hydroxide solution containing potassium hydroxide in an amount 1.1 times or more the number of moles of anionic groups calculated from the acid value, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 5.5, to obtain an additive liquid for abrasives containing 0.2 mass % of styrene / maleic acid copolymer potassium salt.

[0089] Example 3 A styrene / maleic acid half ester copolymer (weight average molecular weight 5,000 to 10,000, acid value 220 mgKOH / g) was dissolved in an aqueous potassium hydroxide solution containing potassium hydroxide in an amount 1.1 times or more the number of moles of anionic groups calculated from the acid value, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 5.5, yielding an additive liquid for abrasives containing 0.2 mass % of styrene / maleic acid half ester copolymer potassium salt.

[0090] Example 4 A methyl acrylate / butyl acrylate / methacrylic acid copolymer (weight average molecular weight 16,000, acid value 150 mgKOH / g) was dissolved in an aqueous KOH solution containing at least 1.1 times the number of moles of anionic groups calculated from the acid value, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 6, yielding an additive liquid for an abrasive containing 0.6 mass % of a methyl acrylate / butyl acrylate / methacrylic acid copolymer potassium salt.

[0091] Example 5 The same styrene / maleic acid copolymer as in Example 1 was dissolved in an aqueous ammonia solution containing ammonia in an amount 1.1 times or more the number of moles of anionic groups calculated from the acid value of the copolymer, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 5.5, thereby obtaining an additive liquid for abrasives containing 0.2 mass % of styrene / maleic acid copolymer ammonium salt.

[0092] Example 6 The same styrene / maleic acid copolymer as in Example 2 was dissolved in an aqueous ammonia solution containing at least 1.1 times the molar amount of ammonia calculated from the acid value of the copolymer relative to the anionic groups, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 5.5, yielding an additive liquid for abrasives containing 0.2 mass % of styrene / maleic acid copolymer ammonium salt.

[0093] Example 7 The same styrene / maleic acid half ester copolymer as in Example 3 was dissolved in an aqueous ammonia solution containing at least 1.1 times the molar amount of ammonia calculated from the acid value of the copolymer relative to the anionic groups, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 5.5, yielding an additive liquid for abrasives containing 0.2 mass % of styrene / maleic acid half ester copolymer ammonium salt.

[0094] Example 8 The same methyl acrylate / butyl acrylate / methacrylic acid copolymer as in Example 4 was dissolved in an aqueous ammonia solution containing at least 1.1 times the molar amount of ammonia calculated from the acid value of the copolymer relative to the anionic groups, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 6, yielding an additive liquid for abrasives containing 0.6% by mass of methyl acrylate / butyl acrylate / methacrylic acid copolymer ammonium salt.

[0095] Example 9 A styrene / methacrylic acid copolymer (weight average molecular weight 50,000, acid value 500 mgKOH / g) was dissolved in an aqueous ammonia solution containing at least 1.1 times the molar amount of ammonia calculated from the acid value of the copolymer, based on the anionic group, while heating to 60° C. Subsequently, water and a pH adjuster were added to adjust the pH to 5, yielding an additive liquid for abrasives containing 0.6% by mass of styrene / methacrylic acid copolymer ammonium salt.

[0096] [Abrasives] The above-mentioned abrasive dispersion and the additive liquid for the abrasives of Examples 1 to 9 were mixed in a mass ratio of 1:1 to prepare the abrasives of Examples 1 to 9.

[0097] [Evaluation] The composition of each abrasive in Examples 1 to 9 and X １ , X ２ and X ３ The calculation results are shown in Table 1.

[0098]

[0099] As shown in Example 9, anionic polymers with high acid values ​​exhibited excellent interaction with abrasive grains, even when dissolved in an aqueous ammonia solution, and coarsening of the abrasive grains was suppressed. On the other hand, in Examples 5 to 8, which used anionic polymers with low acid values, coarsening of the abrasive grains was observed, and it was found that anionic polymers with acid values ​​of 400 mg KOH / g or less made it difficult to suppress abrasive grain aggregation. In contrast, even when using the same polymers as in Examples 5 to 8, in Examples 1 to 4, which used alkali metal salts of the anionic polymers during dissolution, suppression of coarsening of the abrasive grains was observed. It is presumed that the anionic polymers in Examples 1 to 4 were dispersed without agglomeration, and exhibited excellent interaction with the abrasive grains.

[0100] Next, the following filter test was carried out using the abrasives of Examples 2 and 6. <Filter Test> A polypropylene filter (pore size 1 μm) was prepared as a filter. The abrasive was passed through the filter at a flow rate of 1 L / min, and the differential pressure was measured after 1.5 minutes. Note that no differential pressure was observed at the start of the filter test.

[0101] The abrasive of Example 6 showed an increase in the differential pressure in the filter test, with a differential pressure of 0.05 MPa occurring after 2 minutes, and coarse particles that could not pass through the filter were observed. It is presumed that these coarse particles are likely to cause polishing scratches on the polished surface. １ ~X ３ In the polishing agent of Example 2, where X is lower than the predetermined value, no increase in the differential pressure was observed in the filter test, and it was confirmed that no coarse particles that could not pass through the filter were generated. １ is 1.5 or less, X ２ is 7.0 or less, and / or X ３ According to the present polishing agent having a pH of 10 or less, even when an anionic polymer with a low acid value is used, the generation of coarse particles can be suppressed, and the occurrence of polishing scratches that may occur on the polished surface can be suppressed.

[0102] <Evaluation of Polishing Scratches> Polishing was carried out under the following conditions using the abrasives of Examples 1, 2, 5, and 7. Polishing apparatus: Fully automatic CMP apparatus (FREX300X, manufactured by Ebara Corporation) Polishing pad: Two-layer pad (IC-1570, manufactured by Nitta DuPont) Polishing pad conditioner: Diamond pad conditioner (A165, manufactured by 3M) Polishing pressure: 21 kPa Polishing platen rotation speed: 100 rpm Polishing head rotation speed: 102 rpm Abrasive supply rate: 250 mL / min Polishing object: Wafer with a silicon dioxide film formed on a 12-inch silicon substrate by plasma CVD using tetraethoxysilane or monosilane as a raw material.

[0103] After polishing, each wafer was thoroughly brush-cleaned with a fluorine-based cleaner and dried. A laser was then irradiated onto the wafer surface using a wafer surface inspection device (WM-10, manufactured by Takano Corporation), and the reflected light was used to count the number of polishing scratches with a size of 0.1 μm or more. The area measured was the area excluding a 10 mm wide area from the outer edge of the wafer.

[0104] As a result of the evaluation of polishing scratches, when the number of polishing scratches per unit area in Example 5 was set to 1, the number was 0.71 in Example 1, 0.79 in Example 2, and 1.93 in Example 7. Thus, it was demonstrated that the abrasive of the present disclosure can significantly suppress the occurrence of polishing scratches.

[0105] According to the present invention, high-speed polishing can be achieved, for example, in CMP of a surface to be polished that includes an insulating film. Therefore, the polishing method of the present invention is suitable for polishing insulating films for STI in the manufacture of semiconductor devices.

[0106] This application claims priority based on Japanese Patent Application No. 2023-119429, filed on July 21, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0107] 1...silicon substrate, 2...stopper film, 3...trench, 4...silicon oxide film, 20...polishing device, 21...semiconductor substrate, 22...polishing head, 23...polishing surface plate, 24...polishing pad, 25...abrasive, 26...abrasive supply pipe

Claims

1. Abrasive grains, an anionic polymer, and water, wherein the acid value of the anionic polymer is 400 mgKOH / g or less, and X is calculated by the following formula (1): １ is 1.5 or less. １ = N １１ / N １２ ... (1) where N １１ is the number of particles having a particle size of 0.56 μm or more contained per unit mass of abrasive grains in the abrasive, and N １２ is the number of particles having a particle diameter of 0.56 μm or more contained per unit mass of abrasive in an abrasive dispersion containing the abrasive, a dispersant, and water.

2. Abrasive grains, an anionic polymer, and water, wherein the acid value of the anionic polymer is 400 mgKOH / g or less, and X is calculated by the following formula (2): ２ The abrasive has a viscosity of 7.0 or less. ２ = N ２１ / N ２２ ... (2) where N ２１ is the number of particles having a particle size of 0.79 μm or more contained per unit mass of abrasive grains in the abrasive, and N ２２ is the number of particles having a particle size of 0.79 μm or more contained per unit mass of abrasive in an abrasive dispersion containing the abrasive, a dispersant, and water.

3. Abrasive grains, an anionic polymer, and water, wherein the acid value of the anionic polymer is 400 mgKOH / g or less, and X is calculated by the following formula (3): ３ is 10 or less. ３ = N ３１ / N ３２ ... (3) where N ３１ is the number of particles having a particle size of 0.98 μm or more contained per unit mass of abrasive grains in the abrasive; N ３２ is the number of particles having a particle diameter of 0.98 μm or more contained per unit mass of abrasive in an abrasive dispersion containing the abrasive, a dispersant, and water.

4. The abrasive according to any one of claims 1 to 3, wherein the abrasive grains comprise at least one kind selected from the group consisting of silica particles, alumina particles, zirconia particles, cerium compound particles, titania particles, germania particles, composite particles thereof, and core-shell type particles.

5. The abrasive of claim 4, wherein the abrasive grains include cerium compound particles.

6. The abrasive of claim 4, wherein the abrasive grains include ceria particles.

7. An abrasive according to any one of claims 1 to 3, wherein the content of the abrasive grains is 0.01% by mass to 10.0% by mass relative to the total mass of the abrasive.

8. The polishing agent according to any one of claims 1 to 3, wherein the anionic polymer is a copolymer containing a hydrophobic monomer and an anionic monomer.

9. The polishing agent according to any one of claims 1 to 3, wherein the weight average molecular weight of the anionic polymer is 2,000 to 50,000.

10. An abrasive according to any one of claims 1 to 3, wherein the content of the anionic polymer is 0.02 mass% to 5 mass% based on the total mass of the abrasive.

11. The polishing agent according to any one of claims 1 to 3, further comprising a pH adjuster.

12. The polishing agent according to any one of claims 1 to 3, having a pH of 4 to 8.

13. A polishing method in which a surface to be polished of a semiconductor substrate is brought into contact with a polishing pad while supplying an abrasive, and polishing is performed by the relative movement of the two, wherein the abrasive is an abrasive as defined in any one of claims 1 to 3.

14. A method for producing semiconductor components, comprising the steps of: obtaining semiconductor components by dicing a semiconductor substrate having a surface to be polished by the polishing method according to claim 13 into individual pieces.

15. A method for producing an additive liquid for abrasives containing a salt of an anionic polymer having an acid value of 400 mgKOH / g or less, comprising the following steps (1) or (2): (1) dissolving an alkali metal salt of the anionic polymer in water, (2) dissolving the anionic polymer in an aqueous alkali metal hydroxide solution containing an alkali metal in an amount 1.0 times or more the number of moles of anionic groups calculated from the acid value of the anionic polymer.

16. The method for producing an additive liquid for an abrasive according to claim 15, wherein the alkali metal is at least one selected from the group consisting of lithium, sodium, potassium, rubidium and cesium.

17. A method for producing an abrasive according to any one of claims 1 to 3, comprising mixing abrasive grains with the additive liquid for an abrasive obtained by the production method according to claim 15.

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