JP6790790B2 - Polishing liquid, polishing liquid set and substrate polishing method - Google Patents

Description

The present invention relates to a polishing liquid, a polishing liquid set, and a method for polishing a substrate.

In the field of semiconductor manufacturing, with the improvement of high performance of VLSI devices, the limit of the conventional miniaturization technology on the extension line is to achieve both high integration and high speed that can meet the above high performance. There is. Therefore, while advancing the miniaturization of semiconductor elements, a technique for making wiring into multiple layers (highly integrated in the vertical direction) has been developed. One of the most important techniques in the process required for such multi-layer wiring is chemical mechanical polishing (chemical mechanical polishing, hereinafter referred to as "CMP") technique. In multi-layer wiring, it is essential to flatten the device layer by layer to ensure the depth of focus of lithography. This is because if the device has irregularities, it may be difficult to focus in the exposure process or it may not be possible to form a fine wiring structure.

Such CMP technology includes, for example, flattening of an interlayer insulating film or the like, and a plug after embedding a silicon oxide film (a film containing silicon oxide) in a metal wiring (for example, a plug of Al, Cu, Co, W or the like). Flattening, or flattening of the insulating film between metal wirings (organosilicate glass, carbon-containing silicon oxide film (SiOC film) such as MSQ; plasma oxide film such as BPSG, HDP-SiO, p-TEOS, etc.) It is also applied to the flattening of the plasma oxide film to be embedded after forming the element separation structure, and is an indispensable technique for semiconductor manufacturing.

Japanese Patent No. 4564735

By the way, in recent years, in order to improve the performance of LSI, it has been studied to use SiOC having a lower relative permittivity at a place where a plasma oxide film has been conventionally applied. However, when SiOC is polished using a conventional polishing liquid, a sufficient polishing rate tends not to be obtained. Therefore, it is required to improve the polishing speed of SiOC for the polishing liquid for such an application as compared with the conventional one.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a polishing liquid capable of improving the polishing speed of SiOC. Another object of the present invention is to provide a polishing liquid set for obtaining the polishing liquid. Furthermore, an object of the present invention is to provide a method for polishing a substrate using the polishing liquid.

The polishing liquid (polishing liquid for SiOC polishing) according to the present invention includes abrasive grains containing cerium, a structural unit represented by the following formula (IA), and a structure represented by the following formula (IB). It contains a polysaccharide having at least one selected from the group consisting of units and water, and has a pH of 6.0 or more.

According to the polishing liquid according to the present invention, the polishing speed of SiOC can be improved.

By the way, in the technique of Patent Document 1, it is attempted to improve the polishing rate of SiOC by using a polyether-modified silicone. However, the technique of Patent Document 1 cannot obtain a sufficient polishing rate of SiOC. On the other hand, according to the polishing liquid according to the present invention, a sufficient polishing rate of SiOC can be obtained.

Further, a semiconductor manufacturing method for stopping polishing of SiOC by using a stopper material such as silicon nitride or polysilicon is being studied. In this case, there is a demand to improve the polishing rate of SiOC while suppressing the polishing rate of the stopper material. On the other hand, according to the polishing liquid according to the present invention, it is possible to improve the polishing speed of SiOC while suppressing the polishing speed of the stopper material.

The abrasive grains preferably contain at least one selected from the group consisting of cerium oxide and cerium hydroxide.

The polishing liquid according to the present invention may further contain a pH adjuster.

The polishing liquid according to the present invention may further contain a polymer compound having at least one selected from the group consisting of a carboxylic acid group (hereinafter, also referred to as a "carboxyl group" in some cases) and a carboxylic acid base. As a result, it is possible to reduce the dishing of the SiOC film in the recess (a phenomenon in which the recess after polishing is dented like a dish) (see FIG. 1).

The content of the polymer compound is preferably 0.001 to 2% by mass based on the total mass of the polishing liquid.

The polishing liquid according to the present invention may contain a nonionic polymer. As a result, the polishing rate of the stopper material (polysilicon or the like) can be reduced, and the polishing rate ratio of SiOC to the stopper material (polysilicon or the like) can be increased.

The polishing liquid according to the present invention may contain an organic acid.

One aspect of the present invention relates to the use of the polishing liquid for polishing a surface to be polished containing SiOC. That is, one aspect of the polishing liquid according to the present invention is preferably used for polishing the surface to be polished containing SiOC.

In the polishing liquid set according to the present invention, the constituent components of the polishing liquid are stored separately as the first liquid and the second liquid, and the first liquid contains the abrasive grains and water, and the second liquid is contained. The liquid contains the polysaccharide and water. According to the polishing liquid set according to the present invention, the same effect as that of the polishing liquid according to the present invention can be obtained.

The method for polishing a substrate according to the present invention may include a step of polishing the surface to be polished of the substrate using the polishing liquid. According to such a method for polishing a substrate, the same effect as that of the polishing liquid according to the present invention can be obtained.

The method for polishing a substrate according to the present invention includes a step of polishing the surface to be polished of the substrate using a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set. You may. According to such a method for polishing a substrate, the same effect as that of the polishing liquid according to the present invention can be obtained.

According to the present invention, it is possible to provide a polishing liquid, a polishing liquid set, and a method for polishing a substrate, which can improve the polishing speed of SiOC. According to the present invention, SiOC can be polished and removed. The present invention can be used for CMP of semiconductor substrates. The present invention can be used to polish the surface to be polished containing SiOC.

According to the present invention, it is possible to provide the use of a polishing liquid or a polishing liquid set for polishing SiOC. According to the present invention, it is possible to provide the use of a polishing liquid or a polishing liquid set for CMP of a semiconductor substrate. According to the present invention, it is possible to provide the use of a polishing liquid or a polishing liquid set for polishing a surface to be polished containing SiOC.

It is sectional drawing of the cross-section of the polishing process at the time of forming the STI structure of a semiconductor.

Hereinafter, the polishing liquid, the polishing liquid set, and the polishing liquid or the polishing method of the substrate using the polishing liquid set according to the embodiment of the present invention will be described in detail.

<Definition>
In the present specification, the term "process" is included in this term not only as an independent process but also as long as the desired action of the process is achieved even if it cannot be clearly distinguished from other processes. Is done. The numerical range indicated by using "~" indicates a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively. The amount of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. The "polishing rate" means the rate at which the material is removed per unit time (removal rate = Removal Rate). "Material to be polished" means a material exposed on the surface to be polished. The "material to be polished" means a material to be positively polished and removed at a high polishing rate. “A or B” may include either A or B, or both. “A or more” in the numerical range means A and a range exceeding A. “A or less” in the numerical range means A and a range less than A.

<Abrasive liquid>
The polishing liquid (polishing liquid for SiOC polishing) according to the present embodiment is a composition that comes into contact with the surface to be polished during polishing, and is, for example, a polishing liquid for CMP. The polishing liquid according to the present embodiment contains at least abrasive grains, specific polysaccharides, and water, and the pH of the polishing liquid is 6.0 or more. Hereinafter, essential components and components that can be arbitrarily added will be described.

(Abrasive grain)
In the present embodiment, the abrasive grains contain cerium from the viewpoint of obtaining a polishing action on SiOC. The constituents of the abrasive grains containing cerium include cerium oxide (cerium), cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromide, cerium bromide, cerium chloride, cerium oxalate, and nitrate. Examples thereof include cerium, cerium carbonate, and cerium-modified products. Examples of the cerium-modified product include those obtained by modifying the surface of particles containing cerium oxide, cerium hydroxide and the like with an alkyl group, and composite particles in which other particles are attached to the surface of particles containing cerium. From the viewpoint of stabilizing the polishing rate of SiOC, the abrasive grains preferably contain at least one selected from the group consisting of cerium oxide and cerium hydroxide, and more preferably contain cerium oxide. As the abrasive grains containing cerium, particles containing cerium oxide (hereinafter referred to as "cerium oxide particles"), particles containing cerium hydroxide (cerium hydroxide particles), and the like can be used.

The cerium oxide particles are not particularly limited, and known particles can be used. Above all, the cerium oxide particles are preferably obtained by oxidizing cerium salts such as carbonates, nitrates, sulfates and oxalates. Examples of the oxidation method include a firing method in which the cerium salt is fired at 600 to 900 ° C., a chemical oxidation method in which the cerium salt is oxidized using an oxidizing agent such as hydrogen peroxide, and the like.

When cerium oxide particles are used, the larger the crystallite diameter (diameter of the crystallites) of the cerium oxide particles and the smaller the crystal strain (that is, the better the crystallinity), the higher the polishing speed is possible. Polishing materials tend to be scratched. From the above viewpoint, preferable cerium oxide particles include particles composed of two or more crystallites and having a crystal grain boundary. Of these, particles having a crystallite diameter of 5 to 300 nm are more preferable. Further, as another preferable cerium oxide particle, colloidal ceria particles having a crystallite diameter of 5 to 300 nm (for example, colloidal ceria manufactured by Rhodia) can be mentioned.

The average particle size of the abrasive grains is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 50 nm or more, from the viewpoint of obtaining a better polishing rate with respect to SiOC. The average particle size of the abrasive grains is preferably 500 nm or less, more preferably 400 nm or less, still more preferably 300 nm or less, from the viewpoint that the material to be polished is not easily scratched. From these viewpoints, the average particle size of the abrasive grains is preferably 10 to 500 nm, more preferably 20 to 400 nm, and even more preferably 50 to 300 nm.

Here, the average particle size of the abrasive grains is measured using a laser diffraction type particle size distribution meter Mastersizer Microplus (manufactured by Malvern, trade name (“Mastersizer” is a registered trademark)) with a refractive index of 1.93 and absorption: 0. It means the value of D50 (median cumulative diameter of volume distribution) of the measured sample to be measured. For the measurement of the average particle size, a sample having an appropriate content (for example, a content having a measured transmittance (H) of 60 to 70% with respect to a He-Ne laser) is used. When the polishing liquid containing abrasive grains is stored separately as a cerium slurry in which abrasive grains are dispersed in water and an additive liquid, the cerium slurry can be diluted to an appropriate content for measurement. it can.

The abrasive grains may contain a component other than cerium. The constituent components of such abrasive grains are selected from the group consisting of, for example, silica, alumina, zirconia, manganese oxide, magnesium oxide, titania, germania, resin, diamond, silicon carbide, cubic boron nitride, and modified products thereof. At least one of them can be mentioned. The abrasive grains can be used individually by one type or in combination of two or more types. Colloidal alumina can also be used as the alumina. Examples of the modified product include those in which the surface of particles such as silica, alumina, zirconia, titania, germania, manganese oxide, and magnesium oxide are modified with an alkyl group, and composite particles in which other particles are attached to the surface of one particle. Can be mentioned.

The abrasive grains may be obtained by any manufacturing method. For example, as a method for producing an oxide, a solid phase method using calcination or the like; a liquid phase method such as a precipitation method, a sol-gel method, or a hydrothermal synthesis method; a vapor phase method such as a sputtering method, a laser method, or a thermal plasma method may be used. Can be used.

When the abrasive grains are agglomerated, the agglomerated abrasive grains may be mechanically crushed. As the pulverization method, for example, a dry pulverization method using a jet mill or the like and a wet pulverization method using a planetary bead mill or the like are preferable. For jet mills, for example, the methods described in "Chemical Engineering Proceedings", Vol. 6, No. 5, (1980), pp. 527-532 can be applied.

When the abrasive grains are applied to the polishing liquid, it is preferable to disperse the abrasive grains in water, which is the main dispersion medium, to obtain a slurry. Examples of the dispersion method include a dispersion treatment using a normal stirrer, a method using a homogenizer, an ultrasonic disperser, a wet ball mill, and the like. The dispersion method and particle size control method are described in, for example, "Complete Works of Dispersion Technology" [Information Organization, Inc., July 2005], Chapter 3, "Latest Development Trends and Selection Criteria for Various Dispersers". Can be used. Further, the dispersibility of the abrasive grains can be improved by lowering the electric conductivity of the dispersion liquid containing the abrasive grains (for example, 500 mS / m or less). As a method of lowering the electric conductivity of the dispersion liquid, solid-liquid separation is performed by centrifugation or the like in order to separate the abrasive grains and the dispersion medium, the supernatant liquid (dispersion medium) is discarded, and a dispersion medium having low electric conductivity is added. Method of redispersion; methods using ultrafiltration, ion exchange resin and the like can be mentioned.

The abrasive grains dispersed by the above method may be further made into fine particles. Examples of the method of micronization include a sedimentation classification method (a method in which abrasive grains are centrifuged by a centrifuge and then forcibly settled to take out only the supernatant liquid). In addition, a high-pressure homogenizer that causes the abrasive grains in the dispersion medium to collide with each other at high pressure may be used.

The content of abrasive grains containing cerium (for example, cerium oxide particles) is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total mass of the polishing liquid, from the viewpoint of easily suppressing aggregation of abrasive grains. 5, 5% by mass or less is more preferable, 3% by mass or less is particularly preferable, and 1% by mass or less is extremely preferable. The content of abrasive grains containing cerium (for example, cerium oxide particles) is preferably 0.01% by mass or more based on the total mass of the polishing liquid, from the viewpoint that the effect of improving the polishing speed of SiOC can be easily obtained. 1% by mass or more is more preferable, and 0.2% by mass or more is further preferable. From these viewpoints, the content of abrasive grains (for example, cerium oxide particles) is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, based on the total mass of the polishing liquid. 2 to 5% by mass is more preferable.

The content of the abrasive grains is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, based on the total mass of the polishing liquid, from the viewpoint of easily suppressing the aggregation of the abrasive grains. 3% by mass or less is particularly preferable, and 1% by mass or less is extremely preferable. The content of abrasive grains is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and 0, based on the total mass of the polishing liquid, from the viewpoint that the effect of improving the polishing speed of SiOC can be easily obtained. .2% by mass or more is more preferable. From these viewpoints, the content of abrasive grains is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and 0.2 to 5% by mass, based on the total mass of the polishing liquid. More preferred.

(Additive)
The polishing liquid according to this embodiment contains an additive. Here, the "additive" is a polishing liquid other than the abrasive grains and water in order to adjust polishing characteristics such as polishing speed and polishing selectivity; and polishing liquid characteristics such as abrasive grain dispersibility and storage stability. Refers to the substance contained in.

[Polysaccharide]
The polishing liquid according to the present embodiment is at least one selected as an additive from the group consisting of the structural unit represented by the following formula (IA) and the structural unit represented by the following formula (IB). Contains polysaccharides with. By using such a polysaccharide, the effect of improving the polishing rate of SiOC can be obtained. The factors for obtaining such an effect are not clear, but the following factors can be mentioned, for example. That is, the ether binding site of the polysaccharide acts on SiOC, and the surface of SiOC becomes hydrophilic. As a result, it is considered that the abrasive grains are likely to adhere to SiOC and the polishing speed is improved. On the other hand, it is considered that polymers having an ether bond other than polysaccharides also act on SiOC, but when the effect of improving the polishing speed of SiOC is low due to the steric repulsion of the portion other than the ether bond with the abrasive grains, polishing of SiOC It is considered that the speed may be reduced.

When the polysaccharide contains both the structural unit represented by the formula (IA) and the structural unit represented by the formula (IB), the sequence is not limited and may be regular or random.

Examples of the polysaccharide include sucrose; purulan; amylose; amylopectin; dextrin; dextrin; maltdextrin; cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin; And other oligosaccharides. As the polysaccharide, at least one selected from the group consisting of sucrose, dextrin, dextran and maltose is preferable, and dextrin is more preferable.

The dextrin is a dextrin obtained by decomposing starch and having an aldehyde group at the end of the decomposition product (referred to as "general dextrin" to distinguish it from other dextrins); one that is not easily decomposed in the process of decomposing starch. Indigestible dextrin separated by purification; reduced dextrin in which the aldehyde terminal is reduced by hydrogenation to convert it into a hydroxyl group (for example, powder-reduced starch decomposition product); highly branched cyclic dextrin; dextrin hydrate, etc. Can be mentioned. Any of these compounds can be used as the dextrin.

Examples of the polysaccharides include "NSD" series manufactured by Sanei Saccharification Co., Ltd .; "Sanmart-S" and "Sandeck" series manufactured by Sanwa Stardust Industry Co., Ltd .; , "TK-16", "Fibersol 2", "Fibersol 2H"; "PO" series manufactured by Mitsubishi Corporation Foods Tech Co., Ltd .; "Cruster Dexirin" manufactured by Glico Foods Co., Ltd. and the like.

The lower limit of the degree of condensation of the polysaccharide is 2 or more, preferably 3 or more, and more preferably 5 or more, from the viewpoint of further enhancing the effect of improving the polishing rate of SiOC. In addition, in this specification, "condensation degree of polysaccharide" is the total number in one molecule of the structural unit represented by the formula (IA) and the structural unit represented by the formula (IB). Is defined as.

In the polishing liquid according to the present embodiment, the polysaccharide may be used alone or in combination of two or more for the purpose of adjusting the polishing rate of SiOC.

The weight average molecular weight of the polysaccharide is preferably 250 or more, more preferably 350 or more, still more preferably 500 or more, from the viewpoint of further improving the effect of improving the polishing rate of SiOC. There is no particular limitation on the upper limit of the weight average molecular weight of the polysaccharide. The weight average molecular weight of the polysaccharide can be measured, for example, by gel permeation chromatography (GPC) using a standard polystyrene calibration curve under the following conditions.

{Measurement condition}
Equipment used: LC-20AD (manufactured by Shimadzu Corporation)
Column: Gelpack GL-W540 + 550
Eluent: 0.1M NaCl aqueous solution Measurement temperature: 40 ° C
Column size: 10.7 mm I. D. × 300 mm
Flow rate: 1.0 mL / min (L represents liter. The same shall apply hereinafter)
Sample concentration: 0.2% by mass
Detector: RID-10A (manufactured by Shimadzu Corporation)

The lower limit of the content of the polysaccharide is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, based on the total mass of the polishing liquid, from the viewpoint of further improving the effect of improving the polishing rate of SiOC. It is preferable, 0.1% by mass or more is more preferable, and 0.15% by mass or more is particularly preferable. The upper limit of the content of the polysaccharide is preferably 3.0% by mass or less, more preferably 1.0% by mass or less, based on the total mass of the polishing solution, from the viewpoint of maintaining suitable storage stability. More preferably, it is 5% by mass or less. When a plurality of compounds are used as the polysaccharide, it is preferable that the total content of each compound satisfies the above range.

[Polymer compound A]
The polishing liquid according to the present embodiment may contain a polymer compound A having at least one selected from the group consisting of a carboxylic acid group and a carboxylic acid base. Thereby, the polishing rate of the stopper material (silicon nitride, polysilicon, etc.) can be further reduced, and the polishing rate ratio of SiOC to the stopper material (silicon nitride, polysilicon, etc.) can be further increased. The polymer compound A can be used alone or in combination of two or more. The polymer compound A is a polymer obtained by polymerizing a monomer containing at least one selected from the group consisting of acrylic acid and methacrylic acid, or a salt thereof (hereinafter, these are "(meth) acrylic acid-based polymers". ”). The monomer may contain acrylic acid or another monomer copolymerizable with methacrylic acid (excluding acrylic acid and methacrylic acid).

Examples of the polymer compound A include a homopolymer of acrylic acid (polyacrylic acid), a homopolymer of methacrylic acid (polymethacrylic acid), a copolymer of acrylic acid and methacrylic acid, acrylic acid or methacrylic acid and the above. It may be at least one selected from the group consisting of a polymer of the above-mentioned monomer, a polymer of acrylic acid and methacrylic acid and the other monomer, and salts thereof. Among them, the (meth) acrylic acid-based polymer is selected from the group consisting of a homopolymer of acrylic acid (polyacrylic acid) and a salt thereof from the viewpoint of good adsorption to a material to be polished (insulating material, etc.). It is preferable that it is at least one kind. Examples of the polymer salt (polymer having a carboxylic acid base) include ammonium salts. Examples of the ammonium salt include ammonium polyacrylate and the like. The (meth) acrylic acid-based polymer may be used alone or in combination of two or more.

Examples of the other monomer (an acrylic acid or another monomer copolymerizable with methacrylic acid) include crotonic acid, pentenic acid, hexenoic acid, heptenoic acid, octenoic acid, nonenic acid, decenoic acid, and undecene. Unsaturated carboxylic acids such as acids, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid and heptadecenoic acid; vinyl compounds such as ethylene, propylene and styrene.

The terminal of the polymer compound A preferably has a small molecular weight and is hydrophilic.

The weight average molecular weight of the polymer compound A is not particularly limited, but is preferably 100 to 150,000, more preferably 1,000 to 80,000. When the weight average molecular weight of the polymer compound A is 100 or more, a good polishing rate tends to be easily obtained when polishing a material to be polished such as silicon oxide such as SiOC. When the weight average molecular weight of the polymer compound A is 150,000 or less, the storage stability of the polishing liquid tends to be less likely to decrease.

The weight average molecular weight of the polymer compound A can be measured by measuring under the following conditions and reading the value obtained as “Mw”.
{Measurement condition}
Equipment used (detector): Hitachi, Ltd., "L-3300" differential refractometer for liquid chromatograph Pump: Hitachi, Ltd., "L-7100" for liquid chromatograph
Degas device: None Data processing: GPC integrator "D-2520" manufactured by Hitachi, Ltd.
Column: Showa Denko KK, "Shodex Asahipak GF-710HQ", inner diameter 7.6 mm x 300 mm
Eluent: 50 mM-Na ₂ HPO ₄ aqueous solution / acetonitrile = 90/10 (v / v)
Measurement temperature: 25 ° C
Flow rate: 0.6 mL / min Measurement time: 30 minutes Sample: Adjust the concentration with a solution having the same composition as the eluent so that the resin concentration is 2% by mass, and filter with a 0.45 μm polytetrafluoroethylene filter. Prepared sample injection volume: 0.4 μL
Standard substance: Polymer Laboratories, narrow molecular weight sodium polyacrylate

The content of the polymer compound A in the polishing liquid is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, based on the total mass of the polishing liquid. The content of the polymer compound A is preferably 2% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, based on the total mass of the polishing liquid. When the content of the polymer compound A is 0.001 to 2% by mass, the amount of dishing, the dependence on the wiring density, and the like can be reduced, and the surface flatness after polishing can be improved.

[Organic acid component B]
The polishing liquid according to the present embodiment may contain at least one organic acid component B selected from the group consisting of organic acids and organic acid salts. This makes it easier to improve the flatness of the material to be polished (for example, silicon oxide such as SiOC) after polishing. More specifically, when the surface to be polished having irregularities is polished, in addition to being able to shorten the polishing time, it is easy to suppress a phenomenon in which a part is excessively polished and dented like a dish (so-called dishing). Become. In addition, over-polishing resistance is significantly improved.

The organic acid component B is selected from the group consisting of -COOM group, phenolic -OM group, -SO ₃ M group, -O-SO ₃ M group, -PO ₄ M ₂ group and -PO ₃ M ₂ group. Compounds having at least one type (where M represents a cation) are preferred.

Examples of M include H; NH ₄ ; alkali metals such as Na and K; alkaline earth metals such as Ca and Mg; metals capable of trivalent such as Al, Fe and Cr; and rare earth metals such as Ce. .. Among them, trivalent metals are preferable, and Al is more preferable.

The organic acid component B and the polymer compound A may be used in combination. It is considered that the organic acid component B interacts with the polymer compound A to form a strong film on the surface of the surface to be polished. More specifically, for example, the carboxyl group (anionic) possessed by the polymer compound A electrostatically attracts cations (such as M above) in the organic acid component B, and the cations are used as nuclei. It is considered that the polymer compound A becomes "curled" and is adsorbed on the surface to be polished to form a protective film. This protective film is stronger than the protective film formed by the "non-curled" polymer compound A, and is considered to have a high flatness improving effect. Further, it is considered that the organic acid portion in the organic acid component B suppresses the dissociation of the carboxyl group in the polymer compound A. It is considered that this increases the hydrophobicity of the polymer compound A and facilitates adsorption on the surface to be polished.

Specific examples of organic acids include dicarboxylic acid, acetic acid, propionic acid, butyric acid, valeric acid, cyclohexanecarboxylic acid, phenylacetic acid, benzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, and o-methoxybenzoic acid. , M-methoxybenzoic acid, p-methoxybenzoic acid, acrylic acid, methacrylic acid, crotonic acid, pentenic acid, hexenoic acid, heptenoic acid, octenoic acid, nonenic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecene Acids, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, isobutyric acid, isovaleric acid, silicic acid, quinaldic acid, nicotinic acid, 1-naphthoic acid, 2-naphthoic acid, picolinic acid, vinylacetic acid, phenylacetic acid, phenoxyacetic acid, 2-Francarboxylic acid, mercaptoacetic acid, levulinic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonandicarboxylic acid, 1,10 -Decandicarboxylic acid, 1,11-undecanediocarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,15-pentadecanedicarboxylic acid, 1,16- Hexadecanedicarboxylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, quinophosphate, quinic acid, naphthalic acid, phthalic acid, isophthalic acid, terephthalic acid, glycolic acid, lactic acid, 3-hydroxypropionic acid, 2- Hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 5-hydroxyvaleric acid, quinic acid, quinurenic acid, salicylic acid, tartaric acid, aconitic acid, ascorbic acid, acetylsalicylic acid, acetylapple acid, acetylenedicarboxylic acid Acid, acetoxysuccinic acid, acetacetic acid, 3-oxoglutaric acid, atropic acid, atrolactinic acid, anthraquinonecarboxylic acid, anthracenecarboxylic acid, caproic acid, isocaproic acid, isocanphoronic acid, isocrotonic acid, 2-ethyl-2-hydroxybutyric acid, Ethylmalonic acid, ethoxyacetic acid, oxaloacetic acid, oxydiacetic acid, 2-oxobutyric acid, camphoronic acid, citric acid, glioxylic acid, glycidic acid, glyceric acid, glucaric acid, gluconic acid, croconic acid, cyclobutanecarboxylic acid, cyclohexanedicarboxylic acid , Diphenylacetic acid, di-O-benzoyl tartrate, dimethylsuccinic acid, dimethoxyphthalic acid, tartronic acid, tannic acid, thiophenecarboxylic acid , Tiglyconic acid, desoxalic acid, tetrahydroxysuccinic acid, tetramethylsuccinic acid, tetronic acid, dehydroacetic acid, teconic acid, tropic acid, vanillic acid, paraconic acid, hydroxyisophthalic acid, hydroxysilic acid, hydroxynaphthoic acid, o -Hydroxyphenylacetic acid, m-hydroxyphenylacetic acid, p-hydroxyphenylacetic acid, 3-hydroxy-3-phenylpropionic acid, pivalic acid, pyridinedicarboxylic acid, pyridinetricarboxylic acid, pyruvate, α-phenylsilicate acid, phenylglyce Sidic acid, phenylsuccinic acid, phenylacetic acid, phenyllactic acid, propiolic acid, sorbic acid, 2,4-hexadiene diic acid, 2-benzilidenpropionic acid, 3-benzilidenpropionic acid, benzilidenmalonic acid, benzylic acid, benzenetricarboxylic acid, 1,2-benzenediacetic acid, benzoyloxyacetic acid, benzoyloxypropionic acid, benzoylgiic acid, benzoylacetic acid, O-benzoyllactic acid, 3-benzoylpropionic acid, galvanic acid, mesooxaic acid, 5-methylisophthalic acid, 2-methylcrotonic acid , Α-Methylsilicic acid, methylsuccinic acid, methylmalonic acid, 2-methylbutyric acid, o-methoxysilicic acid, p-methoxysilicic acid, mercaptosuccinic acid, mercaptoacetic acid, O-lactoyl lactic acid, malic acid, leuconic acid , Leucic acid, logizonic acid, rosolic acid, α-ketoglutaric acid, L-alcorbic acid, isulonic acid, galacturonic acid, glucuronic acid, pyroglutamic acid, ethylenediamine tetraacetic acid, triacetic acid cyanide, aspartic acid, glutamic acid, N'-hydroxy Carbobic acids such as ethyl-N, N, N'-triacetic acid, nitrilotriacetic acid;
Phenols such as o-aminophenol, m-aminophenol, p-aminophenol;
Methane sulfonic acid, ethane sulfonic acid, propane sulfonic acid, butane sulfonic acid, pentan sulfonic acid, hexane sulfonic acid, heptane sulfonic acid, octane sulfonic acid, nonan sulfonic acid, decane sulfonic acid, undecane sulfonic acid, dodecane sulfonic acid, tridecane Sulfonic acid, tetradecane sulfonic acid, pentadecane sulfonic acid, hexadecane sulfonic acid, heptadecane sulfonic acid, octadecane sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid, toluene sulfonic acid (for example, p-toluene sulfonic acid), hydroxyethane sulfonic acid, hydroxy Sulfonic acids such as phenol sulfonic acid and anthracene sulfonic acid;
Phosphonic acids such as decylphosphonic acid and phenylphosphonic acid are preferable. Carboxylic acid is expected to have effects such as improving the dispersibility of abrasive grains.

Further, the organic acid component B has one or more protons of the main chain of the above-mentioned carboxylic acid, sulfonic acid, and phosphonic acid, and an atom or atom such as F, Cl, Br, I, OH, CN, NO _2. It may be a derivative substituted with a group.

The organic acid component B can be used alone or in combination of two or more.

The content of the organic acid component B is 0.001% by mass based on the total mass of the polishing liquid from the viewpoint of easily improving the flatness of the material to be polished (for example, silicon oxide such as SiOC) after polishing. The above is preferable, 0.005% by mass or more is more preferable, and 0.01% by mass or more is further preferable. The content of the organic acid component B is preferably 1% by mass or less, more preferably 0.5% by mass or less, and 0, based on the total mass of the polishing liquid, from the viewpoint of easily improving the polishing rate of the material to be polished. .1% by mass or less is more preferable, 0.06% by mass or less is particularly preferable, and 0.05% by mass or less is extremely preferable.

[Nonionic polymer]
The polishing liquid according to the present embodiment can contain a nonionic polymer (excluding the polymer compound A). As a result, the polishing rate of the stopper material (silicon nitride, polysilicon, etc.) can be reduced, and the polishing rate ratio of SiOC to the stopper material (silicon nitride, polysilicon, etc.) can be increased.

The nonionic polymer is, for example, a nonionic surfactant. The nonionic polymer is not particularly limited, but is polyoxypropylene, polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether derivative, polyoxypropylene glyceryl. Ether-type surfactants such as ether, polyethylene glycol, methoxypolyethylene glycol, and oxyethylene adducts of acetylene-based diols; ester-type surfactants such as sorbitan fatty acid ester and glycerol volate fatty acid ester; amino such as polyoxyethylene alkylamine Ether-type surfactants; ether ester-type surfactants such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerol volate fatty acid ester, and polyoxyethylene alkyl ester; alkanolamides such as fatty acid alkanolamide and polyoxyethylene fatty acid alkanolamide. Type surfactants; oxyethylene adducts of acetylene diols; polyvinylpyrrolidone; polyacrylamide; polydimethylacrylamide; glycerin-based polymers such as polyglycerin and polyglycerin derivatives; polyoxyethylene sorbitan monopalmitate and the like.

The content of the nonionic polymer is preferably 0.002 to 0.5% by mass, more preferably 0.003 to 0.3% by mass, and 0.005 to 0, based on the total mass of the polishing liquid. 1% by mass is more preferable. When the content of the nonionic polymer is 0.002% by mass or more, an increase in the polishing rate of the stopper material (polysilicon or the like) can be further suppressed. When the content of the nonionic polymer is 0.5% by mass or less, the polishing rate of SiOC tends to be improved.

When the polishing liquid is stored as a polishing liquid set described later, at least one of the slurry and the additive liquid can contain a nonionic polymer. When the slurry containing the abrasive grains contains a nonionic polymer, the nonionic polymer can be used as a dispersant. Regarding the content of the nonionic polymer in the polishing liquid, it is preferable that the total amount of the nonionic polymer in the slurry and the nonionic polymer in the additive liquid satisfies the above range.

[Dispersant]
The polishing liquid according to the present embodiment may contain a dispersant (excluding the polymer compound A and the nonionic polymer). The content of the dispersant is preferably 0.001 to 4% by mass based on the total mass of the abrasive grains. Examples of the dispersant include a water-soluble anionic dispersant, a water-soluble nonionic dispersant, a water-soluble cationic dispersant, and a water-soluble amphoteric dispersant. Of these, a water-soluble anionic dispersant or a water-soluble cationic dispersant is preferable from the viewpoint of having a large electrostatic repulsive force and good dispersibility. The polymer compound A or the nonionic surfactant can also be used to disperse the abrasive grains.

When the polishing liquid according to the present embodiment contains a cationic polymer, the abrasive grains containing cerium (cerium oxide particles and the like) tend to have a positive charge. In this case, the polishing rate of silicon nitride (SiN) or the like can be suppressed. Examples of the cationic polymer include homopolymers and copolymers of diallyldialkylammonium salts, homopolymers and copolymers of diallylalkylamine salts, homopolymers and copolymers of diallylamine salts, and other polyallylamines. Be done.

Specifically, examples of the diallyldialkylammonium salt include diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldimethylammonium iodide, diallyldimethylammonium methylsulfate, diallyldimethylammonium ethylsulfate, diallylethylmethylammonium chloride, and diallylethyl. Methylammonium bromide, diallylethylmethylammonium iodide, diallylethylmethylammonium methylsulfate, diallylethylmethylammonium ethylsulfate, diallyldiethylammonium chloride, diallyldiethylammonium bromide, diallyldiethylammonium iodide, diallyldiethylammonium methylsulfate, diallyldiethylammonium Examples thereof include ethyl sulfate, diallylmethylpropylammonium chloride, diallylmethylpropylammonium bromide, diallylmethylpropylammonium iodide, diallylmethylpropylammonium methylsulfate, and diallylmethylpropylammonium ethylsulfate.

Examples of the diallylalkylamine salt include diallylmethylamine hydrochloride, diallylmethylamine hydrobromide, diallylmethylamine hydride, diallylmethylamine sulfate, diallylmethylaminemethanesulfonate, and diallylethylamine hydrochloride. Salt, diallylethylamine hydrobromide, diallylethylamine hydroiodide, diallylethylamine sulfate, diallylethylamine methanesulfonate, diallylpropylamine hydrochloride, diallylpropylamine hydrobromide, diallylpropylamine iodide Hydroxates, diallylpropylamine sulfates, and diallylpropylamine methanesulfonates can be mentioned.

Examples of the diallylamine salt include diallylamine hydrochloride, diallylamine hydrobromide, diallylamine hydroiodide, diallylamine sulfate, and diallylamine methanesulfonate.

[PH regulator]
The polishing liquid may contain a pH adjuster. However, if the polishing liquid is in a predetermined pH range even if the pH adjusting agent is not contained, the pH adjusting agent may not be added in particular.

The pH adjusting agent is not particularly limited, and examples thereof include inorganic acids, organic bases, and inorganic bases. Examples of the inorganic acid include nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, boric acid and the like. Examples of the organic base include triethylamine, pyridine, piperidine, pyrrolidine, imidazole, 2-methylimidazole, chitosan and the like. Examples of the inorganic base include tetramethylammonium hydroxide (TMAH), ammonia, potassium hydroxide, sodium hydroxide and the like. The pH may be adjusted using the organic acid component. In addition, a buffer solution may be added to stabilize the pH. Examples of such a buffer solution include an acetate buffer solution and a phthalate buffer solution. Each of the pH adjuster and the buffer solution can be used alone or in combination of two or more.

[Other additives]
The polishing liquid according to the present embodiment may further contain other additives for the purpose of adjusting polishing characteristics such as polishing speed; characteristics such as dispersibility of abrasive grains. Other additives may be used alone or in combination of two or more.

Examples of other dispersants include water-soluble polymers used for adjusting polishing characteristics such as flatness and in-plane uniformity. Further, the polishing liquid may contain a solvent other than water (for example, a polar solvent such as ethanol, acetic acid, or acetone) as an additive, if necessary.

Examples of the water-soluble polymer include polysaccharides having a structural unit represented by the formula (IA) or the formula (IB) such as alginic acid, pectic acid, carboxymethyl cellulose, agar, curdlan, and guar gum. Excludes); Vinyl-based polymers such as polyvinyl alcohol and polyacrolean can be mentioned. Here, the "water-soluble polymer" is defined as a polymer that dissolves 0.1 g or more in 100 g of water at 25 ° C.

When a water-soluble polymer is used, the lower limit of the content of the water-soluble polymer is based on the total mass of the polishing liquid from the viewpoint of obtaining the effect of adding the water-soluble polymer while suppressing the sedimentation of abrasive grains. 0.0001% by mass or more is preferable, 0.001% by mass or more is more preferable, and 0.01% by mass or more is further preferable. The upper limit of the content of the water-soluble polymer is preferably 5% by mass or less, preferably 1% by mass, based on the total mass of the polishing liquid, from the viewpoint of obtaining the effect of adding the water-soluble polymer while suppressing the sedimentation of abrasive grains. % Or less is more preferable, and 0.5% by mass or less is further preferable. When a plurality of compounds are used as the water-soluble polymer, it is preferable that the total content of each compound satisfies the above range.

When other additives are used, the content of each of the other additives is 0 based on the total mass of the polishing liquid from the viewpoint of obtaining the effect of adding the other additives while suppressing the sedimentation of abrasive grains. .001 to 10% by mass is preferable. When a plurality of compounds are used as other additives, it is preferable that the total content of each compound satisfies the above range.

(water)
The water used as the medium of the polishing liquid is not particularly limited, but deionized water, ion-exchanged water, ultrapure water and the like are preferable.

(PH of polishing liquid)
The pH of the polishing liquid according to the present embodiment is 6.0 or more from the viewpoint of obtaining the effect of improving the polishing rate of SiOC. The pH of the polishing liquid according to the present embodiment is preferably 6.5 or more, more preferably 7.0 or more, further preferably 7.5 or more, and even more preferably 7.5 or more, from the viewpoint that the effect of improving the polishing rate of SiOC can be easily obtained. .0 or more is particularly preferable. From the viewpoint of safety, the pH of the polishing liquid according to the present embodiment is preferably 12 or less, more preferably 11 or less, further preferably 10 or less, and particularly preferably 9.5 or less. pH is defined as pH at a liquid temperature of 25 ° C.

The pH of the polishing liquid according to this embodiment can be measured with a pH meter (for example, model number PHL-40 manufactured by Electrochemical Meter Co., Ltd.). Specifically, for example, a phthalate pH buffer solution (pH 4.01), a neutral phosphate pH buffer solution (pH 6.86), and a borate pH buffer solution (pH 9.18) are used as standard buffer solutions. After calibrating the pH meter at three points, put the electrode of the pH meter in the polishing solution and measure the value after it stabilizes after 2 minutes or more. At this time, the liquid temperatures of the standard buffer solution and the polishing liquid are both set to 25 ° C.

(Type of polishing liquid)
The polishing liquid according to the present embodiment may be stored as a one-component polishing liquid containing at least abrasive grains, the polysaccharide and water, and a slurry (first liquid) and an additive liquid (second liquid) may be stored. The constituent components of the polishing liquid may be stored as a two-component polishing liquid set (for example, a polishing liquid set for CMP) in which the constituent components of the polishing liquid are separated into a slurry and an additive liquid so as to be mixed to obtain the polishing liquid. The slurry contains, for example, abrasive grains and at least water. The additive liquid contains, for example, at least the above-mentioned polysaccharide and water. The polysaccharide and other additives are preferably contained in the additive solution among the slurry and the additive solution. However, the additive having the effect of improving the dispersibility of the abrasive grains is preferably contained in the slurry and the additive liquid. For example, in the polishing liquid set, the constituent components of the polishing liquid are stored separately as a slurry (first liquid) and an additive liquid (second liquid), and the slurry contains abrasive grains and water, and the additive liquid is contained. May contain the polysaccharide and water. The constituent components of the polishing liquid may be stored as a polishing liquid set divided into three or more liquids.

In the polishing liquid set, the slurry and the additive liquid are mixed immediately before or at the time of polishing to prepare a polishing liquid. Further, the one-component polishing liquid may be stored as a storage liquid for a polishing liquid having a reduced water content, and may be diluted with water immediately before or during polishing. The two-component polishing liquid set may be stored as a storage liquid for slurry and a storage liquid for additive liquid with a reduced water content, and may be used by diluting with water immediately before or during polishing.

In the case of a one-component polishing liquid, the method of supplying the polishing liquid onto the polishing surface plate is a method of directly feeding the polishing liquid; the storage liquid for the polishing liquid and water are sent by separate pipes. A method of merging, mixing and supplying these; a method of mixing and supplying a storage liquid for polishing liquid and water in advance can be used.

When storing as a two-component polishing liquid set divided into a slurry and an additive liquid, the polishing speed can be adjusted by arbitrarily changing the composition of these two liquids. When polishing using a polishing liquid set, there are the following methods as a method of supplying the polishing liquid onto the polishing surface plate. For example, a method in which the slurry and the additive liquid are sent through separate pipes, and these pipes are merged, mixed and supplied; the slurry storage liquid, the additive liquid storage liquid and the water are sent through separate pipes. A method of merging, mixing and supplying these; a method of mixing and supplying a slurry and an additive liquid in advance; and a method of previously mixing and supplying a storage liquid for a slurry, a storage liquid for an additive liquid and water can be used. it can. Further, a method of supplying the slurry and the additive liquid in the polishing liquid set onto the polishing surface plate can also be used. In this case, the surface to be polished is polished using the polishing liquid obtained by mixing the slurry and the additive liquid on the polishing surface plate.

<Manufacturing method of polishing liquid>
The polishing liquid manufacturing method according to the present embodiment is a polishing liquid manufacturing method for removing at least a part of SiOC by CMP. The method for producing a polishing liquid according to the present embodiment includes at least a polishing liquid manufacturing process for obtaining a polishing liquid by mixing abrasive grains, polysaccharides, and water. In the polishing liquid manufacturing process, each component may be mixed at the same time, or each component may be mixed sequentially. The polishing liquid manufacturing method according to the present embodiment may include a step of obtaining abrasive grains containing cerium before the polishing liquid manufacturing step.

The method for producing a polishing liquid according to the present embodiment preferably includes a dispersion step of dispersing abrasive grains in water. The dispersion step is, for example, a step of mixing the abrasive grains and the dispersant. In this case, the dispersant is preferably added in the step of obtaining a cerium slurry (cerium oxide slurry or the like). That is, it is preferable that the cerium slurry contains a dispersant. In the dispersion step, for example, abrasive grains, a dispersant, and water are mixed, and the abrasive grains are dispersed in water to obtain a cerium slurry.

<Method of polishing the substrate>
The polishing method according to the present embodiment includes a step of polishing the surface to be polished containing SiOC by using a polishing liquid. The method of polishing the substrate according to the present embodiment may include a polishing step of polishing the surface to be polished of the substrate using the one-component polishing liquid, and the slurry and the additive liquid in the polishing liquid set are mixed. It may be provided with a polishing step of polishing the surface to be polished of the substrate with the polishing liquid obtained above. Further, the method for polishing the substrate according to the present embodiment may be a method for polishing a substrate having a single material or a plurality of materials to be polished, and may be, for example, the one-component polishing liquid or the slurry in the polishing liquid set. A polishing step of selectively polishing SiOC with respect to the stopper material by using a polishing liquid obtained by mixing with an additive liquid may be provided. In this case, the substrate may have, for example, a member containing SiOC and a member (stopper) containing a stopper material. As the stopper material, a material such as silicon nitride or polysilicon is preferable, and silicon nitride is more preferable.

In the polishing step, for example, the polishing liquid is supplied between the polishing target material and the polishing pad in a state where the polishing target material of the substrate having the polishing target material is pressed against the polishing pad (polishing cloth) of the polishing platen. , The substrate and the polishing platen are moved relatively to polish the material to be polished. In the polishing step, for example, at least a part of the material to be polished is removed by polishing.

FIG. 1 is a schematic cross-sectional view of a polishing process when forming an STI structure of a semiconductor. The method of polishing the substrate according to the present embodiment will be further described with reference to FIG. First, as shown in FIG. 1A, a wafer (silicon substrate or the like) 1 having irregularities formed on its surface, which is composed of concave portions (trench portions) and convex portions (active portions), and a convex portion of the wafer 1 A substrate 100 having a silicon nitride film (SiN film) 2 formed on the wafer 1 and a SiOC film 3 formed so as to fill the irregularities on the surface of the wafer 1 is prepared.

Next, the SiOC film 3 is polished with the polishing liquid, and the polishing is stopped when the SiOC film 3 on the convex portion is completely removed and the silicon nitride film 2 is exposed, whereby FIG. 1 (B) The substrate 200 shown in the above is obtained. In the substrate 200 after polishing, it is preferable to reduce the dishing of the SiOC film 3 in the recess. Specifically, it is preferable that the dishing amount 6 which is the value obtained by subtracting the thickness 5 of the SiOC film 3 in the recess from the depth 4 of the recess is small.

Examples of the substrate to be polished include a substrate, and for example, a material to be polished is formed on a substrate related to semiconductor element manufacturing (for example, a semiconductor substrate on which an STI pattern, a gate pattern, a wiring pattern, etc. are formed). The substrate can be mentioned. The substrate may be a substrate having one or more types of materials to be polished, or a substrate having one or two or more types of materials to be polished and one or two or more types of stopper materials. Good. Examples of the material to be polished include insulating materials such as SiOC (carbon-containing silicon oxide. Organosilicate glass, MSQ, etc.) and silicon oxide (excluding SiOC). Examples of the stopper material include silicon nitride and polysilicon. The material to be polished may be in the form of a film (film to be polished). The material to be polished and the stopper material may be in the form of a film (film to be polished and stopper film).

The material to be polished (for example, SiOC) formed on such a substrate is polished with the polishing liquid to remove excess portions, thereby eliminating the unevenness of the surface of the material to be polished and the entire surface of the material to be polished. A smooth surface is obtained over. The polishing liquid according to this embodiment is preferably used for polishing the surface to be polished containing SiOC.

Hereinafter, the polishing method according to the present embodiment will be further described by taking the polishing method of the semiconductor substrate as an example. In the polishing method according to the present embodiment, as the polishing apparatus, a general polishing apparatus having a holder capable of holding a substrate such as a semiconductor substrate having a surface to be polished and a polishing surface plate to which a polishing pad can be attached is used. Can be used. For example, a motor whose rotation speed can be changed is attached to each of the holder and the polishing surface plate. Examples of the polishing device include a polishing device manufactured by Applied Materials (trade name: Mira-3400, Reflection LK) and a polishing device manufactured by Ebara Seisakusho Co., Ltd. (trade name: F-REX300).

As the polishing pad, a general non-woven fabric, foam, non-foam or the like can be used. As the material of the polishing pad, polyurethane, acrylic resin, polyester, acrylic-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly4-methylpentene, cellulose, cellulose ester, polyamide (for example, nylon (trade name)) And aramid), polyimide, polyimideamide, polysiloxane copolymer, oxylan compound, phenol resin, polystyrene, polycarbonate, epoxy resin and other resins can be used. As the material of the polishing pad, foamed polyurethane and non-foamed polyurethane are particularly preferable from the viewpoint of obtaining more excellent polishing speed and flatness. The polishing pad may be grooved so that the polishing liquid can be collected.

Although there are no restrictions on the polishing conditions, the rotation speed of the polishing surface plate is preferably 200 min ^-1 (rpm) or less so that the semiconductor substrate does not pop out, and the polishing pressure (machining load) applied to the semiconductor substrate causes polishing scratches. From the viewpoint of sufficiently suppressing the above, 100 kPa or less is preferable. During polishing, it is preferable to continuously supply the polishing liquid to the polishing pad with a pump or the like. There is no limit to the amount of this supply, but it is preferable that the surface of the polishing pad is always covered with the polishing liquid.

For the semiconductor substrate after polishing, it is preferable to thoroughly wash the substrate in running water to remove particles adhering to the substrate. For cleaning, dilute hydrofluoric acid or aqueous ammonia may be used in addition to pure water, and a brush may be used to improve the cleaning efficiency. Further, after cleaning, it is preferable to wipe off the water droplets adhering to the semiconductor substrate with a spin dryer or the like and then dry the semiconductor substrate.

Examples of the substrate to be polished in the polishing method according to the present embodiment include individual semiconductors such as diodes, transistors, compound semiconductors, thermistas, varistor, and thyristors; DRAM (dynamic random access memory), SRAM (static random).・ Access memory), EPROM (eraseable programmable read-only memory), mask ROM (mask read-only memory), EEPROM (electrical eraseable programmable read-only memory), flash memory, etc. Memory element; theoretical circuit element such as microprocessor, DSP, ASIC; integrated circuit element such as compound semiconductor represented by MMIC (monolithic microwave integrated circuit); hybrid integrated circuit (hybrid IC), light emitting diode, charge coupling element A substrate having a photoelectric conversion element such as the above can be applied.

The polishing liquid according to this embodiment is not limited to polishing SiOC, silicon nitride and the like formed on the semiconductor substrate as described in the above-described embodiment, and silicon oxide formed on a wiring plate having a predetermined wiring, Inorganic insulating materials such as glass and silicon nitride; can be applied to polishing of materials mainly containing polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN and the like.

Examples of the electronic component including the substrate polished by the polishing method according to the present embodiment include various ones. Electronic components include not only semiconductor elements, but also optical glasses such as photomasks, lenses, and prisms; inorganic conductive films such as ITO; optical integrated circuits composed of glass and crystalline materials; optical switching elements; optical waveguides; optical fibers. End face; Optical single crystal such as scintillator; Solid laser single crystal; Sapphire substrate for blue laser LED; Semiconductor single crystal such as SiC, GaP, GaAs; Glass substrate for magnetic disk; Magnetic head and the like. In these electronic components, by polishing each layer with the polishing liquid according to the present embodiment, high integration can be achieved and excellent characteristics can be exhibited.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the technical idea of the present invention is not deviated. For example, the material of the polishing liquid and its blending ratio may be a material and a blending ratio other than the material and the blending ratio described in this example, and the composition and structure to be polished are also compositions other than the composition and structure described in this example. And the structure may be used.

<Preparation of cerium oxide powder>
40 kg of commercially available 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 the phase of this powder was identified by X-ray diffraction, it was confirmed that it was cerium oxide. 20 kg of the obtained cerium oxide powder was dry-pulverized using a jet mill to obtain a cerium oxide powder containing cerium oxide particles.

<Preparation of polishing liquid for CMP>
(Example 1)
After mixing 200.0 g of the cerium oxide powder prepared above with 795.0 g of deionized water, 5 g of an aqueous ammonium polyacrylate solution (weight average molecular weight: 8000, 40% by mass) was added. Ultrasonic dispersion was performed with stirring to obtain a cerium oxide dispersion. The ultrasonic dispersion was performed at an ultrasonic frequency of 400 kHz and a dispersion time of 20 minutes.

Then, 1 kg of the cerium oxide dispersion was placed in a 1 L container (height: 170 mm) and allowed to stand, and sedimentation classification was performed. After the classification was performed for 15 hours, the supernatant above the depth of 130 mm from the water surface was pumped up. The obtained supernatant cerium oxide dispersion was diluted with deionized water so that the solid content content was 5% by mass to obtain an aqueous dispersion (slurry) containing cerium oxide particles.

In order to measure the average particle size (D50) of the cerium oxide particles in the aqueous dispersion containing the cerium oxide particles, the dispersion is prepared so that the transmittance (H) at the time of measurement with respect to the He-Ne laser is 60 to 70%. It was diluted to obtain a measurement sample. When the D50 of the measurement sample was measured with a refractive index of 1.93 and an absorption of 0 using a laser diffraction type particle size distribution meter Mastersizer Microplus (manufactured by Malvern, trade name (“Mastersizer” is a registered trademark)), the value of D50 was measured. Was 150 nm.

Water, additives in Table 1 (A1, sucrose, manufactured by Wako Pure Chemical Industries, Ltd., Wako First Class, molecular weight: 342.30), pH adjuster, and aqueous dispersion containing the cerium oxide particles are the same in this order. After blending in a container, the mixture was mixed to prepare a polishing solution for CMP containing 0.50% by mass of cerium oxide particles and 0.10% by mass of an additive. “%” In Tables 1 to 3 indicates “% by mass” and indicates the content based on the total mass of the polishing liquid.

(Examples 2 to 13 and Comparative Examples 1 to 5)
The polishing liquids for CMP shown in Tables 1 to 3 were prepared by mixing in the same procedure as in Example 1. As additives, powder-reduced starch decomposition product (A2, Mitsubishi Corporation Food Tech Co., Ltd., trade name: PO-10), highly branched cyclic dextrin (A3, manufactured by Glico Foods Co., Ltd., trade name: Cruster Dextrin), dextran (A4, manufactured by Wako Pure Chemical Industries, Ltd., Wako First Class, average molecular weight: 32000-45000, trade name: dextran 40000), D (+)-glucose (A5, manufactured by Wako Pure Chemical Industries, Ltd., molecular weight: 180.16 ), N-Acetylglucosamine (A6, manufactured by Toyama Pharmaceutical Industries, Ltd.) was used. In Example 12, a polishing liquid containing a polysaccharide and polyacrylic acid was prepared. In Example 13, a polishing solution containing a polysaccharide, polyacrylic acid, and polyglycerin (nonionic polymer, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., trade name: PGL # 750) was prepared. In Comparative Example 1, a polishing liquid containing no additive was prepared.

(Comparative Example 6)
Water, additives in Table 3 (A1, sucrose, manufactured by Wako Pure Chemical Industries, Ltd., Wako First Class, molecular weight: 342.30), pH adjuster, and aqueous dispersion containing silica particles are placed in the same container in this order. A polishing solution for CMP containing 10.00% by mass of silica particles and 1.00% by mass of an additive was prepared by mixing after blending with. As the silica particles, colloidal silica having an average particle size (average secondary particle size) of 70 nm was used.

The "average particle size" of the silica particles means the average secondary particle size of the silica particles. For the average particle size, the value of D50 (median diameter of volume distribution, cumulative median value) of the polishing liquid measured with a dynamic light scattering type particle size distribution meter (for example, trade name: COOLTER N4 SD manufactured by COOLTER Electricals) is used. Say.

Specifically, the average particle size was measured by the following procedure. First, about 100 μL of the polishing liquid is weighed and diluted with ion-exchanged water so that the content of silica particles is about 0.05% by mass (content at which the transmittance (H) at the time of measurement is 60 to 70%). To obtain a diluted solution. Then, the diluted solution was put into the sample tank of the dynamic light scattering type particle size distribution meter, and the average particle size was measured by reading the value displayed as D50.

<pH measurement>
The pH of the polishing liquid for CMP was measured with a pH meter (model number PHL-40 manufactured by Electrochemical Meter Co., Ltd.). Using phthalate pH buffer (pH 4.01), neutral phosphate pH buffer (pH 6.86) and borate pH buffer (pH 9.18) as standard buffers, set three pH meters. After calibrating, the electrode of the pH meter was put into a polishing solution, and the value after lapsed for 2 minutes or more and stabilized was measured. The measurement results are shown in Tables 1 to 3.

<Polishing evaluation>
As the test wafer for CMP evaluation, each of the following blanket substrates (Blanket wafers) (a) to (c) having no pattern formed was used.
Blanket substrate (a): A substrate having a SiOC film (manufactured by Lam Research) on a silicon (Si) substrate (diameter: 300 mm).
Blanket substrate (b): A substrate having a silicon nitride film on a silicon (Si) substrate (diameter: 300 mm).
Blanket substrate (c): A substrate having a polysilicon film on a silicon (Si) substrate (diameter: 300 mm).

A polishing apparatus (manufactured by Applied Materials, trade name: ReflectionLK) was used for polishing the test wafer for CMP evaluation. The test wafer for CMP evaluation was set in the holder to which the suction pad for mounting the substrate was attached. A polishing pad made of a porous urethane resin (manufactured by Roam & Haas Japan Co., Ltd., model number IC1010) was attached to a polishing surface plate having a diameter of 600 mm of the polishing apparatus. The holder was placed on a polishing surface plate with the surface on which the film to be polished (SiOC film, silicon nitride film or polysilicon film) was arranged facing down, and the processing load was set to 3.0 psi (20.6 kPa).

While the CMP polishing liquid to the polishing platen was added dropwise at a rate of 300 mL / min, the polishing plate and the CMP evaluation test wafer respectively ^93min -1, rotated at 87min ^-1, test CMP Rating The wafer was polished. Polishing was performed for 60 seconds. The wafer after polishing using a PVA brush (polyvinyl alcohol brush) was thoroughly washed with pure water and then dried.

The film thickness of the film to be polished before and after polishing is measured using an optical interference type film thickness measuring device (device name: F80) manufactured by Filmometrics Co., Ltd., and the polishing rate of the blanket wafer is calculated from the average value of the film thickness change. did. The unit of polishing rate is nm / min. The evaluation results are shown in Tables 1 to 3.

The symbols in the above table are as follows.
A1: Sucrose A2: PO-10 (powder reduced starch decomposition product)
A3: Cruster Dextrin (highly branched cyclic dextrin)
A4: Dextran 40000 (Dextran)
A5: D (+)-glucose A6: N-acetylglucosamine

From the results of Tables 1 to 3, Examples 1 to 11 showed a higher polishing rate of the SiOC film as compared with Comparative Examples. Further, from the results of Examples 1, 2, 6 to 11, it can be seen that even when sucrose having a degree of condensation of polysaccharides of 2 is used, there is an effect of improving the polishing rate of SiOC. From the results of Example 12, it can be seen that the polymer compound A has an effect of improving the stop characteristics of the silicon nitride film. From the results of Example 13, it can be seen that the nonionic polymer has an effect of improving the stop characteristics of the polysilicon film.

Further, from the results in Table 3, Comparative Example 2 using D (+)-glucose, Comparative Example 3 using PGL # 750, Comparative Example 4 and Comparative Example 5 having a pH of less than 6.0, and silica as abrasive grains. In Comparative Example 6 using particles, the polishing rate of the SiOC film was lower than the polishing rate of the SiOC film of the example.

1 ... Wafer, 2 ... Silicon nitride film, 3 ... SiOC film, 4 ... Depth of recess, 5 ... Thickness of SiOC film in the recess after polishing, 6 ... Dishing amount, 100, 200 ... Base.

Claims (11)

Abrasive grains containing cerium and
A polysaccharide having at least one selected from the group consisting of a structural unit represented by the following formula (IA) and a structural unit represented by the following formula (IB).
Contains water,
A polishing liquid for SiOC polishing having a pH of 6.0 or more.

The polishing liquid according to claim 1, wherein the abrasive grains contain at least one selected from the group consisting of cerium oxide and cerium hydroxide. The polishing solution according to claim 1 or 2, further containing a pH adjuster. The polishing solution according to any one of claims 1 to 3, further containing a polymer compound having at least one selected from the group consisting of a carboxylic acid group and a carboxylic acid base. The polishing liquid according to claim 4, wherein the content of the polymer compound is 0.001 to 2% by mass based on the total mass of the polishing liquid. The polishing liquid according to any one of claims 1 to 5, further containing a nonionic polymer. The polishing liquid according to any one of claims 1 to 6, further containing an organic acid. The polishing liquid according to any one of claims 1 to 7, which is used for polishing a surface to be polished containing SiOC. The constituent component of the polishing liquid according to any one of claims 1 to 8 is stored separately as a first liquid and a second liquid, and the first liquid contains the abrasive grains and water, and the above. A polishing liquid set in which the second liquid contains the polysaccharide and water. A method for polishing a substrate, comprising a step of polishing the surface to be polished of the substrate using the polishing liquid according to any one of claims 1 to 8. A method for polishing a substrate, comprising a step of polishing the surface to be polished of the substrate with a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set according to claim 9.

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