Cerium oxide particles, their manufacturing process, and their use in chemical and mechanical polishing.

Abstract

The present invention relates to cerium oxide particles having a roughness index RI of at least 5, a process for their manufacture and their use in chemical mechanical polishing applications. [0010] TIFF2024511723000015.tif20170

Description

[Technical Field]

[0001] This invention relates to cerium oxide particles and polishing compositions thereof, particularly their use as components in chemical mechanical polishing (CMP) compositions. The invention also relates to a method for preparing cerium oxide particles.

[0002] More specifically, the present invention provides cerium oxide particles that exhibit good polishing properties when used in CMP compositions, and a simple, economical, and easily implementable method for preparing such particles. [Background technology]

[0003] Cerium oxide is commonly used in polishing applications. With the development of the electronics industry, there is an increasing need for compositions to polish various components such as disks and dielectric compounds. These compositions, typically commercialized in the form of dispersions, must exhibit certain properties. For example, they must be able to remove material to a high degree, which is reflected in their polishing ability. They must also have the lowest possible defectability; the term "defectability" specifically refers to the amount of scratches that appear on the substrate after treatment with the composition. Typically, these dispersions contain submicron-sized particles, i.e., generally less than 300 nm, for reasons of stability and ease of use. In addition, if the particles in such dispersions are too fine, their polishing ability decreases, while if the particles are too large, it can contribute to increased defectability.

[0004] Accordingly, several types of cerium oxide particles, specifically manufactured for CMP applications and manufactured with precision, are known from prior art.

[0005] International Publication No. 2015 / 197656 discloses metal-doped cerium oxide particles.

[0006] International Publication No. 08043703 discloses a suspension in a liquid phase of cerium oxide particles, wherein the particles are secondary particles having an average size of up to 200 nm, and the secondary particles include primary particles having an average size of up to 100 nm, the standard deviation of which is up to 30% of the average size of the primary particles.

[0007] International Publication No. 2015 / 091495 discloses a suspension of cerium oxide particles in a liquid phase, wherein the particles comprise secondary particles including primary particles, the secondary particles having an average size D50 between 105 and 1000 nm and a standard deviation between 10 and 50% of the average size of the secondary particles; and the primary particles having an average size D50 between 100 and 300 nm and a standard deviation between 10 and 30% of the average size of the primary particles.

[0008] In addition to novel cerium oxide particles that exhibit improved performance in CMP, the inventors believe there is still room for improvement in obtaining a simple, economical, and industrial-scale method for preparing these particles. [Overview of the Initiative]

[0009] The applicant has skillfully fabricated novel cerium oxide particles that can solve the problems described above.

[0010] Therefore, one subject of the present invention is cerium oxide particles having a roughness index (RI) of at least 5, particularly in the range of 5 to 20, and especially in the range of 6 to 17. More specifically, the roughness index of the particles is defined by the following formula:

number

[0011] "SSA size" represents the theoretical average particle size derived from the BET (Brunauer, Emmett, and Teller) specific surface area. More specifically, it can be calculated according to the following formula:

number

[0012] To the best of our knowledge, the roughness index achieved by the particles of the present invention is higher than that of prior art cerium oxide particles. Such particles are expected to contribute to achieving higher polishing efficiency when used as abrasive particles in CMP compositions or in CMP processes.

[0013] The present invention also relates to a process for producing cerium oxide particles of the present invention, comprising at least the following steps: (a) Under an inert atmosphere, (i) an aqueous solution of a base and (ii) NO3 - Ce III , optionally Ce IV (iii) a step of contacting an aqueous solution containing and (iii) an organic acid or a salt thereof to obtain a mixture, wherein the organic acid is a substituted or unsubstituted C1-C20 alkyl, alkenyl or alkynyl carboxylic acid; (b) A step of subjecting the mixture obtained in step (a) to heat treatment; (c) A step of optionally acidifying the mixture obtained in step (b); (d) A step of optionally washing the solid material obtained at the end of step (b) or (c) with water; (e) A step of deaggregating the particles by optionally subjecting the solid material obtained at the end of step (d) to mechanical treatment; This also relates to the process, including the process itself.

[0014] Advantageously, this process enables the preparation of the cerium oxide particles of the present invention in a simple manner.

[0015] The present invention also relates to cerium oxide particles obtainable or obtained by the process described above, to a dispersion of the cerium oxide particles of the present invention in a liquid medium, to the use of said dispersion or of the particles of the present invention for preparing a CMP composition, to a CMP composition comprising said dispersion or said particles, to a polishing process using said CMP composition for removing a part of a substrate, and to a semiconductor comprising the substrate polished thereby. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] [Figure 1] An image of the particles of the present invention observed by transmission electron microscopy. [Figure 2] An image of the particles of the present invention observed by transmission electron microscopy. [Figure 3] An image of the particles of the present invention observed by transmission electron microscopy. [Figure 4] An image of the particles of the present invention observed by transmission electron microscopy. [Figure 5] An image of prior art cerium oxide particles observed by transmission electron microscopy. DETAILED DESCRIPTION OF THE INVENTION

[0017] These photographs were taken using a JEM-1400 (JEOL) apparatus operating at 120 kV.

[0018] In the present disclosure, expressions such as “... to... included” or similar expressions should be understood to include the boundary values.

[0019] The term "cerium oxide" in relation to the particles of this invention refers to cerium(IV) oxide, also known as ceric oxide. Cerium oxide generally has a purity of at least 99.8% by weight relative to the weight of the oxide. Cerium oxide is generally crystalline ceric oxide. This oxide may contain some impurities other than cerium. These impurities may originate from the raw materials or starting materials used in the preparation process of cerium oxide. The sum of the proportions of impurities is generally less than 0.2% by weight relative to the cerium oxide. Residual nitrates are not considered impurities in this application.

[0020] The term "dispersion" in relation to the cerium oxide particle dispersion of the present invention refers to a system consisting of fine, submicron-sized solid cerium oxide particles stably dispersed in a liquid medium, wherein the particles may optionally contain residual amounts of bound or adsorbed ions, such as nitrate ions or ammonium ions.

[0021] The present invention will now be described in more detail according to its different embodiments.

[0022] As previously explained, one subject of the present invention lies in cerium oxide particles having a roughness index (RI) of at least 5. More specifically, the roughness index of the particles of the present invention can be in the range of 5 to 20, in particular in the range of 6 to 17, and more specifically in the range of 7 to 14.

[0023] The particle roughness index (RI) is defined by the following formula:

number

number

[0024] TEM size is the average effective size of the particles. This is preferably measured with a large number of particles, for example, at least 80, preferably at least 90, and more preferably at least 100, so that statistical analysis can be performed. This measurement is usually performed on one or more photographs of the same sample of cerium oxide particles. The particles are preferably held so that their images are clearly visible in the photographs. According to one embodiment, which will be described in detail later, the number of particles having a spheroidal shape preferably corresponds to at least 80.0%, more specifically at least 90.0%, and even more specifically at least 95.0% of the particles.

[0025] The specific surface area (SSA) can be determined by adsorbing nitrogen onto cerium oxide particle powder using the Brunauer-Emmett-Teller method (BET method). This method is disclosed in standard ASTM D3663-03 (re-approved in 2015). This method is also described in the periodical "The Journal of the American Chemical Society, 60, 309 (1938)". The specific surface area can be automatically measured using Micromeritics' TriStar 3000 instrument, according to the manufacturer's guidelines. Before measurement, the powder sample should be degassed by heating it in still air at a maximum temperature of 210°C to remove adsorbed chemical species.

[0026] By measuring the BET specific surface area, the SSA size can be calculated according to the formula shown above: given the SSA, the theoretical size of cerium(IV) oxide particles, assuming the particles are spherical, can be obtained from the above formula. Therefore, the ratio of TEM size to SSA size serves as an indicator of particle roughness: the higher this ratio, the coarser the particles. It is believed that using cerium oxide particles with a high roughness index in polishing processes such as CMP improves efficiency.

[0027] According to one preferred embodiment, the cerium oxide particles of the present invention have a spheroidal shape. To the best of our knowledge, particles possessing a specific roughness index and a specific spheroidal shape contribute to CMP and yield improved results compared to using conventional cerium oxide particles (i.e., those that are not spheroidal and do not possess the required roughness index).

[0028] The sphericality ratio (SR) of the cerium oxide particles of the present invention, which are ellipsoidal in shape, can be between 0.8 and 1.0, more specifically between 0.85 and 1.0, and even more specifically between 0.90 and 1.0. Preferably, the SR can be between 0.90 and 1.0 or between 0.95 and 1.0. The sphericality of the particles is calculated from the measured values ​​of the outer circumference P and projected area A of the particles using the following formula.

number

[0029] The SR of an ideal sphere is 1.0, while that of a spheroidal particle is less than 1.0.

[0030] Circularity is typically determined by dynamic image analysis (DIA). Examples of equipment that can be used to perform DIA include Retsch's CAMSIZER® P4 or Sympatec's QicPic®.

[0031] Circularity can be measured in more detail according to ISO 13322-2 (2006). In general, DIA requires the analysis of a statistically significant number of particles (e.g., at least 80).

[0032] According to one embodiment, the average size of the cerium oxide particles of the present invention may be 30 nm or more. In many cases, the particle size is 70 nm or more. The average size of the cerium oxide particles of the present invention may be 500 nm or less. In many cases, the particle size is 300 nm or less, particularly 150 nm or less. In one embodiment, the average size of the cerium oxide particles of the present invention may be between 140 and 300 nm, particularly between 145 and 270 nm, more specifically between 150 and 250 nm, and even more specifically between 155 and 240 nm. The average size is preferably measured from a TEM image. This measurement is preferably performed on at least 80 particles.

[0033] According to one embodiment, the specific surface area of ​​the cerium oxide particles of the present invention may be between 30 and 100 m² / g, more specifically between 32 and 80 m² / g, more specifically between 35 and 70 m² / g, and even more specifically between 36 and 60 m² / g. The specific surface area is measured in powder form by nitrogen adsorption using the Brunauer-Emmett-Teller method (BET method), as previously described.

[0034] In certain embodiments, the specific surface area is between 15 and 100 m² / g, more specifically between 20 and 40 m² / g.

[0035] In another embodiment, the present invention relates to cerium oxide particles, wherein the particles are given by the following formula:

number

number

[0036] In certain embodiments, the roughness index RI in this embodiment is less than 5.

[0037] To the best of our knowledge, the carbon weight ratio of the cerium oxide particles in this embodiment contributes to the compatibility of the cerium oxide particles with other components of dispersions and abrasive compositions commonly used in CMP applications.

[0038] The characteristics of the ellipsoid shape, particle size, and specific surface area in this embodiment are as described above.

[0039] According to one embodiment, the carbon weight ratio of the cerium oxide particles of the present invention can be in the range of 0.001% to 5% by weight, particularly in the range of 0.1% to 2.5% by weight. This trace amount of carbon may be a trace of a synthesis method that requires a specific organic acid used in the preparation of the particles. The elemental carbon content (dosage) can be determined using a carbon-sulfur analyzer such as a Horiba EMIA 320-V2.

[0040] The present invention also relates to a process for producing cerium oxide particles of the present invention, comprising at least the following steps: (a) Under an inert atmosphere, (i) an aqueous solution of a base and (ii) NO3 - Ce III , optionally Ce IV (iii) a step of contacting an aqueous solution containing and (iii) an organic acid or a salt thereof to obtain a mixture, wherein the organic acid is a substituted or unsubstituted C1-C20 alkyl, alkenyl or alkynyl carboxylic acid; (b) subjecting the mixture obtained in step (a) to heat treatment; (c) optionally acidifying the mixture obtained in step (b); (d) optionally washing the solid material obtained at the end of step (b) or (c) with water; (e) optionally subjecting the solid material obtained at the end of step (d) to mechanical treatment to deflocculate the particles; also relates to a process comprising.

[0041] It is advantageous to use high purity salts and components. The purity of the salt can be at least 99.5% by weight, more particularly at least 99.9% by weight.

[0042] In step (a), an aqueous solution (i) of a base is used. In particular, hydroxide type products can be used as the base. Examples include hydroxides of alkali metals or alkaline earth metals and aqueous ammonia. Secondary, tertiary or quaternary amines can also be used. The aqueous solution of the base can also be pre-degassed by bubbling an inert gas through it.

[0043] When the amount of the base used in step (a) is expressed as the molar ratio of base / Ce in total, this is preferably included between 4 and 10, and preferably included between 5 and 8.

[0044] In step (a), an aqueous solution (ii) containing NO3 - , Ce III and optionally Ce IV is used. For the preparation of the solution, nitrates or cerium can be used in particular. When Ce IV is present in the aqueous solution, the molar ratio of Ce IV / Ce in total is preferably included between 1 / 500000 and 1 / 4000. This molar ratio can particularly be between 1 / 6000 and 1 / 4000. The molar ratio of Ce IV / Ce in total used in the examples can be used.

[0045] In this preparation method, an aqueous solution of cerium nitrate obtained by the reaction of nitric acid with cerium nitrate hydrate can be used. Cerium nitrate is prepared in the presence of hydrogen peroxide. III Cation to Ce IV It is prepared conventionally by reacting a cerium mononitrate solution with an aqueous ammonia solution to convert it into a cation. It is also particularly advantageous to use a cerium nitrate solution obtained by the electrochemical oxidation method of a cerium mononitrate solution disclosed in French Patent No. 2570087. A cerium nitrate solution obtained according to the teachings of French Patent No. 2570087 may exhibit an acidity of about 0.6 N.

[0046] Process (a) includes Ce IV If Ce IV It can be provided in the form of a salt, which can be cerium(IV) nitrate or cerium ammonium nitrate.

[0047] The amount of nitrate ions in the aqueous solution used in step (a) is NO3 - / Ce III When expressed in molar ratio, it is generally between 1 / 3 and 5 / 1. The acidity of the aqueous solution used in step (a) is preferably between 0.8 N and 12.0 N.

[0048] In step (a), a specific organic acid (iii) or a salt thereof, which is a substituted or unsubstituted C1-C20 alkyl, alkenyl, or alkynyl carboxylic acid, is used. The chain length of the alkyl, alkenyl, or alkynyl group may, more specifically, be C1-C12, C1-C6, or even C1-C3. The organic acid is preferably an alkyl or alkenyl carboxylic acid, more preferably an alkyl carboxylic acid.

[0049] According to one embodiment, the organic acid is substituted. Examples of substituents include halogens, lower alkyl groups (i.e., alkyl groups having fewer than 6 carbon atoms), aryl groups, alkoxy groups, hydroxyl groups, amino groups, alkylamino groups, arylamino groups, alkylsulfinyl groups, alkylsulfonyl groups, arylsulfinyl groups, and arylsulfonyl groups. Preferred substituents are lower alkyl groups, more specifically C1-C3 alkyl groups, and especially methyl groups. This alkyl, alkenyl, or alkynyl group may have one or more substituents, particularly one or more C1-C3 alkyl groups, and especially one or more methyl groups. Preferably, the organic acid is a C1-C6 alkylcarboxylic acid substituted with at least one C1-C3 alkyl group, more preferably a C1-C3 alkylcarboxylic acid substituted with at least one C1-C2 alkyl group, more preferably a C1-C3 alkylcarboxylic acid substituted with at least one methyl group, and even more preferably pivalic acid.

[0050] According to other alternative embodiments, the organic acid is unsubstituted. In this case, the organic acid is preferably an unsubstituted C1-C20 alkyl carboxylic acid, more preferably an unsubstituted C1-C12 alkyl carboxylic acid, more preferably an unsubstituted C1-C6 alkyl carboxylic acid, more preferably an unsubstituted C1-C3 alkyl carboxylic acid, and even more preferably propionic acid.

[0051] In further embodiments, the organic acid is a dicarboxylic acid, for example, a C2-C8 dicarboxylic acid, such as malonic acid, succinic acid, preferably adipic acid. The dicarboxylic acid may be substituted, as previously described herein, and in particular may be unsubstituted.

[0052] Ammonium salts can be cited as suitable salts of the organic acids mentioned above.

[0053] According to one embodiment, the organic acid exists in the form of an aqueous solution. The concentration of the organic acid in the aqueous solution can be, for example, in the range of 1 to 20% by weight, particularly in the range of 2 to 10% by weight, and more specifically in the range of 3 to 7% by weight. According to another embodiment, a pure, i.e., undiluted organic acid is used.

[0054] The components (i), (ii), and (iii) brought into contact to form the mixture in step (a) can be brought into contact in any order. According to one embodiment, in particular, an aqueous solution of a base (i) and an organic acid (iii) are brought into contact with each other, and the resulting mixture is brought into contact with an aqueous solution (ii) containing cerium nitrate. In this case, since the base solution (i) is already in the form of an aqueous solution, a pure (i.e., undiluted) organic acid (iii) can be used. The contact of the mixture of (i) and (iii) with (ii) may preferably consist of adding (ii) to the mixture while stirring and / or bubbling an inert gas.

[0055] According to an alternative embodiment, an aqueous solution (ii) containing cerium nitrate and an aqueous solution (i) of a base are brought into contact with each other, and the resulting mixture is brought into contact with an organic acid (iii). In this case, the organic acid (iii) can be used in the form of an aqueous solution. The contact of (ii) and (i) can consist of adding (ii) to (i), preferably with stirring and / or bubbling with an inert gas.

[0056] The organic acid (iii) can be used in concentrations ranging from 1 to 245 mmol / L, particularly from 2 to 150 mmol / L, more specifically from 5 to 100 mmol / L, and more specifically from 5 to 50 mmol / L, relative to the total volume of the mixture obtained in step (a). This range is particularly suitable for the formation of well-defined particles.

[0057] The amount of free oxygen in the mixture should be carefully controlled and minimized. For this purpose, components (i), (ii), and (iii) used and / or one or more of the resulting mixture can be degassed by bubbling with an inert gas. The terms “inert gas” or “inert atmosphere” are intended to mean an atmosphere or gas that does not contain oxygen, which may be, for example, nitrogen or argon.

[0058] Step (a) consists of reacting components (i), (ii), and (iii). Step (a) is preferably carried out under an inert atmosphere, particularly in a closed reactor or in a semi-closed reactor with sweeping of an inert gas. Contact is generally carried out in a stirred reactor.

[0059] Process (a) is generally carried out at a temperature between 5°C and 50°C. This temperature can be 20°C to 25°C.

[0060] Step (b) is the heat treatment of the reaction medium obtained at the end of the preceding step. This may consist of (i) a heating sub-step and (ii) a maturation sub-step.

[0061] The heating sub-step (i) may consist of heating the medium to a temperature generally between 75°C and 95°C, more specifically between 80°C and 90°C.

[0062] The maturation sub-process (ii) can consist of maintaining the medium at a temperature between 75°C and 95°C, more specifically between 80°C and 90°C. The duration of maturation sub-process (ii) is between 2 and 20 hours. As a rule of thumb, the higher the temperature of the maturation process, the shorter the duration of the maturation sub-process. For example, if the temperature of the maturation sub-process is between 85°C and 90°C, for example at 88°C, the duration of the maturation sub-process may be between 2 and 15 hours, more specifically between 4 and 15 hours. If the temperature of the maturation sub-process is between 75°C and 85°C, for example at 80°C, the duration of the maturation sub-process may be between 15 and 30 hours.

[0063] While performing process (b), Ce III Ce IV It is oxidized. This process can also be carried out in an inert atmosphere, and the description of this atmosphere in step (a) applies here as well. The heat treatment can also be carried out in a stirred reactor.

[0064] In step (c), the mixture obtained at the end of step (b) can be optionally acidified. This step (c) can be carried out using nitric acid. The reaction mixture can be acidified with HNO3 to a pH of less than 3.0, more specifically between 1.5 and 2.5.

[0065] In step (d), the solid material obtained at the end of step (b) or step (c) is washed with water, preferably deionized water. This operation reduces the amount of nitrates remaining in the dispersion, making it possible to obtain the target conductivity. This step can be carried out by filtering the solid from the mixture and redispersing the solid in water. Filtration and redispersion can be performed several times as needed.

[0066] In step (e), mechanical treatment may be performed to deaggregate the solid material particles obtained at the end of step (d). This step can be carried out by double-jet treatment or ultrasonic deaggregation. Typically, this step sharpens the particle size distribution and reduces the number of large aggregated particles. In one embodiment, the cerium oxide particles are subjected to mechanical deaggregation treatment. In another embodiment, the cerium oxide particles are not subjected to mechanical deaggregation treatment.

[0067] After step (e), the solid material can be dried to obtain cerium oxide particles in powder form. After step (e), a dispersion of cerium oxide particles in a liquid medium can also be obtained by adding water or a mixture of water and a miscible liquid organic compound.

[0068] Another object of the present invention is cerium oxide particles that can be obtained or obtained by the process described above.

[0069] The present invention also relates to a dispersion of cerium oxide particles in a liquid medium. This dispersion comprises the cerium oxide particles and the liquid medium of the present invention. The liquid medium may be water or a mixture of water and a water-miscible organic liquid. This water-miscible organic liquid must not precipitate or aggregate the particles. The water-miscible organic liquid may be, for example, alcohols such as isopropyl alcohol, ethanol, 1-propanol, methanol, and 1-hexanol; ketones such as acetone, diacetone alcohol, and methyl ethyl ketone; or esters such as ethyl formate, propyl formate, ethyl acetate, methyl acetate, methyl lactate, butyl lactate, and ethyl lactate. The water / organic liquid ratio may be between 80 / 20 and 99 / 1 (wt / wt).

[0070] The proportion of cerium oxide particles in the dispersion may range from 1.0% by weight to 40.0% by weight, expressed as the weight of cerium oxide particles relative to the total weight of the dispersion. This proportion may range from 10.0% by weight to 35.0% by weight.

[0071] This dispersion may also have a conductivity of less than 300 μS / cm, more specifically less than 150 μS / cm, and even more specifically less than 100 μS / cm or 50 μS / cm. Conductivity is measured with a HORIBA, Ltd. conductivity meter 9382-10D.

[0072] The cerium oxide particles or dispersions of the present invention can be used to prepare polishing compositions, and more particularly, CMP compositions. These are used as components of polishing compositions, and more particularly, CMP compositions.

[0073] The present invention also relates to CMP compositions. CMP compositions (i.e., chemical mechanical polishing compositions) are polishing compositions used to selectively remove material from the surface of a substrate. They are used in the field of integrated circuits and other electronic devices. In practice, in the manufacture of integrated circuits and other electronic devices, multiple layers of conductive, semiconducting, and dielectric materials are deposited onto or removed from the surface of a substrate. As layers of material are sequentially deposited onto or removed from the substrate, the top surface of the substrate becomes non-planar, and planarization may be required. Surface planarization (i.e., surface "polishing") is the process of removing material from the surface of a substrate to form a uniform and flat surface overall. Planarization is useful for removing undesirable surface shapes and surface defects such as rough surfaces, aggregated material, crystal lattice defects, scratches, and contaminated layers or materials. Planarization is also useful for forming features on a substrate by removing excess deposited material used to fill features and to provide a uniform surface for subsequent metallization and processing.

[0074] Substrates that can be polished with the polishing composition or CMP composition can be, for example, silicon dioxide-based substrates, glass, semiconductors, or wafers.

[0075] The particles or dispersions of the present invention can be used in the preparation of CMP compositions. Therefore, the present invention also relates to CMP compositions comprising cerium oxide particles or dispersions such as those defined above.

[0076] Polishing compositions or CMP compositions typically contain different components other than cerium oxide particles. Polishing compositions may contain one or more of the following components: - Abrasive particles other than cerium oxide particles or abrasive particles other than the abrasive particles of the dispersion of the present invention; and / or - pH adjusters; and / or - Surfactants; and / or - Rheological modifiers such as viscosity improvers and coagulants; and / or - Additives selected from nonionic polymers, cationic polymers, anionic polymers, quaternary ammonium compounds, silanes, sulfonated monomers, phosphonated monomers, acrylates, starches, cyclodextrins, and combinations thereof.

[0077] The pH of abrasive compositions is generally between 1 and 6. Typically, the pH of abrasive compositions is 3.0 or higher. Also, typically, the pH of abrasive compositions is 6.0 or lower.

[0078] The present invention also relates to a method for removing a portion of a substrate, which includes polishing the substrate with an abrasive composition such as those described above.

[0079] Finally, the present invention relates to a semiconductor polished by this method.

[0080] If any disclosure of a patent, patent application, or publication incorporated herein by reference contradicts the description of this application to such an extent that it could obscure certain terms, the description herein shall prevail.

[0081] The present invention will be described in more detail in the examples, but it is not intended to limit the present invention to the examples. [Examples]

[0082] Example 1 A cerium nitrate solution was prepared by mixing 111.3 g of 2.87 M trivalent cerium nitrate, 16.82 g of 68% HNO3, and 3.26 g of deionized water. This solution was placed in a 250 mL semi-closed container. Next, cerium(IV) nitrate was added to this cerium nitrate solution so that the molar ratio of cerium IV to total cerium was 1 / 5000. An aqueous ammonia solution was prepared by mixing 74.55 g of 13.35 M aqueous ammonia and 623.03 g of deionized water. This solution was placed in a 1 L semi-closed reactor with a jacket, and N2 gas was bubbled in at a flow rate of 210 L / h while stirring for 1 hour. The cerium nitrate solution described above was added to the aqueous ammonia solution over approximately 30 minutes under the same stirring and N2 bubbling conditions. An organic acid solution was prepared by adding 0.90 g of pivalic acid to 20 g of deionized water. After bubbling with N2 gas for 1 hour, the solution was added to the reactor. Maintaining the same stirring conditions, the N2 bubbling flow rate was reduced (to less than 10 L / h), and the temperature of the reaction mixture was raised to 85°C over approximately 1 hour and maintained at that temperature for approximately 4 hours. The reaction mixture was cooled and acidified to pH 2 with 68% HNO3. Decanting removed the supernatant, and NH4OH was added to the slurry to adjust the pH to 8.

[0083] The reaction mixture was washed with deionized water by centrifugation. Washing was repeated until the conductivity of the washing solution was less than 0.04 mS / cm.

[0084] The BET specific surface area determined from nitrogen adsorption was 37.9 m² / g. This suspension was observed by TEM, and approximately 80 representative particles from the suspension were counted and measured. The average particle size was 193 nm, and the standard deviation was 39 nm, which corresponds to 20% of the average particle size. The SSA size, determined as described herein, was 22, and the roughness index RI, calculated as described herein, was 8.8. The carbon ratio was determined to be %C = 0.4 wt%. A TEM image of the obtained ellipsoidal rough particles is shown in Figure 1.

[0085] Example 2 A cerium nitrate solution was prepared by mixing 111.3 g of 2.87 M trivalent cerium nitrate, 16.81 g of 68% HNO3, and 3.25 g of deionized water. This solution was placed in a 250 mL semi-closed container. Next, cerium(IV) nitrate was added to this cerium nitrate solution so that the molar ratio of cerium IV to total cerium was 1 / 5000. An aqueous ammonia solution was prepared by mixing 74.20 g of 13.35 M aqueous ammonia, 643.50 g of deionized water, and 0.92 g of pivalic acid. This solution was placed in a 1 L semi-closed reactor with a jacket, and N2 gas was bubbled in at a flow rate of 210 L / h while stirring for 1 hour. The cerium nitrate solution described above was added to the aqueous ammonia solution over approximately 30 minutes under the same stirring and N2 bubbling conditions. Under the same stirring conditions, the N2 bubbling flow rate was reduced (to less than 10 L / h), and the temperature of the reaction mixture was raised to 85°C over approximately 1 hour and maintained at that temperature for approximately 4 hours. The reaction mixture was cooled and acidified to pH 2 with 68% HNO3. Decanting removed the supernatant, and NH4OH was added to the slurry to adjust the pH to 8.

[0086] The reaction mixture was washed with deionized water by centrifugation. Washing was repeated until the conductivity of the washing solution was less than 0.04 mS / cm.

[0087] The BET specific surface area determined from nitrogen adsorption was 44.8 m² / g. This suspension was observed by TEM, and approximately 80 representative particles from the suspension were counted and measured. The average particle size was 165 nm, and the standard deviation was 50 nm, which corresponds to 30% of the average particle size. The SSA size, determined as described herein, was 19, and the roughness index RI, calculated as described herein, was 8.9. The carbon ratio was determined to be %C = 0.37 wt%. A TEM image of the obtained ellipsoidal rough particles is shown in Figure 2.

[0088] Example 3 A cerium nitrate solution was prepared by mixing 222.4 g of 2.87 M trivalent cerium nitrate with 33.9 g of 68% HNO3. This solution was placed in a 250 mL semi-closed container. Next, cerium(IV) nitrate was added to this cerium nitrate solution so that the molar ratio of cerium IV to total cerium was 1 / 5000. An aqueous ammonia solution was prepared by mixing 133.1 g of 15 M aqueous ammonia, 1297.7 g of deionized water, and 0.83 g of pivalic acid. This solution was placed in a 2 L semi-closed reactor with a jacket, and N2 gas was bubbled in at a flow rate of 100 L / h while stirring for 1 hour. The cerium nitrate solution described above was added to the aqueous ammonia solution over approximately 30 minutes under the same stirring and N2 bubbling conditions. Under the same stirring conditions, the N2 bubbling flow rate was reduced (to less than 10 L / h), and the temperature of the reaction mixture was raised to 80°C over approximately 1 hour and maintained at that temperature for approximately 4 hours. The reaction mixture was cooled and acidified to pH 2 with 68% HNO3. Decanting removed the supernatant, and NH4OH was added to the slurry to adjust the pH to 8.

[0089] The reaction mixture was washed with deionized water by centrifugation. The washing process was repeated five times until the conductivity of the washing solution was less than 0.04 mS / cm.

[0090] The BET specific surface area determined from nitrogen adsorption was 23 m² / g. This suspension was observed by TEM, and approximately 150 representative particles were counted and measured individually. The average particle size was 81 nm, and the standard deviation was 30 nm, which corresponds to 37% of the average particle size. The SSA size, determined as described herein, was 36, and the roughness index RI, calculated as described herein, was 2.2. The carbon ratio was determined to be %C = 0.21 wt%. A TEM image of the obtained ellipsoidal rough particles is shown in Figure 3.

[0091] Example 4 A cerium nitrate solution was prepared by mixing 222.4 g of 2.87 M trivalent cerium nitrate with 33.9 g of 68% HNO3. This solution was placed in a 250 mL semi-closed container. Next, cerium(IV) nitrate was added to this cerium nitrate solution so that the molar ratio of cerium IV to total cerium was 1 / 5000. An aqueous ammonia solution was prepared by mixing 133.9 g of 14.9 M aqueous ammonia, 1296.8 g of deionized water, and 1.18 g of adipic acid. This solution was placed in a 2 L semi-closed reactor with a jacket, and N2 gas was bubbled in at a flow rate of 100 L / h while stirring for 1 hour. The cerium nitrate solution described above was added to the aqueous ammonia solution over approximately 30 minutes under the same stirring and N2 bubbling conditions. Under the same stirring conditions, the N2 bubbling flow rate was reduced (to less than 10 L / h), and the temperature of the reaction mixture was raised to 80°C over approximately 1 hour and maintained at that temperature for approximately 4 hours. The reaction mixture was cooled and acidified to pH 2 with 68% HNO3. Decanting removed the supernatant, and NH4OH was added to the slurry to adjust the pH to 8.

[0092] The reaction mixture was washed with deionized water by centrifugation. The washing process was repeated five times until the conductivity of the washing solution was less than 0.04 mS / cm.

[0093] The BET specific surface area determined from nitrogen adsorption was 35 m² / g. This suspension was observed by TEM, and approximately 220 representative particles from the suspension were counted and measured individually. The average particle size was 87 nm, and the standard deviation was 34 nm, which corresponds to 39% of the average particle size. The SSA size, determined as described herein, was 24, and the roughness index RI, calculated as described herein, was 3.6. The carbon ratio was determined to be %C = 0.61 wt%. A TEM image of the obtained ellipsoidal rough particles is shown in Figure 4.

[0094] Comparative Example 1 A cerium nitrate solution was prepared by mixing 139.1 g of 2.87 M trivalent cerium nitrate, 21.1 g of 68% HNO3, and 4 g of deionized water. This solution was placed in a 250 mL semi-closed container. Next, cerium(IV) nitrate was added to this cerium nitrate solution so that the molar ratio of cerium IV to total cerium was 1 / 5000. An aqueous ammonia solution was prepared by mixing 100.5 g of 13.35 M aqueous ammonia and 795.5 g of deionized water. This solution was placed in a 1 L semi-closed reactor with a jacket, and N2 gas was bubbled in at a flow rate of 210 L / h while stirring for 1 hour. The cerium nitrate solution described above was added to the aqueous ammonia solution over approximately 30 minutes under the same stirring and N2 bubbling conditions. Under the same stirring conditions, the N2 bubbling flow rate was reduced (to less than 10 L / h), and the temperature of the reaction mixture was raised to 85°C over approximately 1 hour and maintained at that temperature for approximately 4 hours. The reaction mixture was cooled and acidified to pH 2 with 68% HNO3. Decanting removed the supernatant, and NH4OH was added to the slurry to adjust the pH to 8.

[0095] The reaction mixture was washed with deionized water by centrifugation. Washing was repeated until the conductivity of the washing solution was less than 0.04 mS / cm.

[0096] The BET specific surface area determined from nitrogen adsorption was 16.8 m² / g. This suspension was observed by TEM, and approximately 150 representative particles from the suspension were counted and measured individually. The average particle size was 87 nm, and the standard deviation was 21 nm, which corresponds to 24% of the average particle size. The SSA size, determined as described herein, was 50, and the roughness index RI, calculated as described herein, was 1.7. The TEM image is shown in Figure 5.

Claims

1. A process for producing cerium oxide particles, comprising the following steps: (a) Under an inert atmosphere, (i) an aqueous solution of a base and (ii) NO ３ － Ce ＩＩＩ , optionally Ce ＩＶ A step of contacting an aqueous solution containing (iii) an organic acid or a salt thereof to obtain a mixture, wherein the organic acid is a substituted or unsubstituted C1-C20 alkyl, alkenyl or alkynylcarboxylic acid; (b) A step of subjecting the mixture obtained in step (a) to a heat treatment carried out at a temperature in the range of 75°C to 95°C; A process that includes this.

2. The process according to claim 1, wherein the organic acid is a substituted or unsubstituted C1-C12 alkylcarboxylic acid.

3. The following steps: (c) A step of acidifying the mixture obtained in step (b); (d) A step of washing the solid material obtained at the end of step (b) or (c) with water; (e) A step of de-aggregating the particles of the solid material obtained at the end of step (d) by subjecting it to mechanical treatment; The process according to claim 1 or 2, further comprising at least one of the following.

4. Cerium oxide particles, wherein the particles have a circularity SR between 0.8 and 1.

0. SR is calculated from the measured values ​​of the outer perimeter P and area A of the particle projection image using the following formula: [Math 6] It is calculated using, SR is determined by dynamic image analysis (DIA), using the formula: [Math 4] (Here, "TEM size" represents the average size of particles measured from transmission electron microscope images of at least 80 particles, and "SSA size" is given by the following formula: [Math 5] (Here, SSA represents the BET specific surface area of ​​the particles determined from nitrogen adsorption, and ρ represents the density of cerium(IV) oxide, which is 7.22 g / cm³.) ３ Cerium oxide particles characterized in that the roughness index RI (representing the theoretical average particle size according to ) is at least 2, and the particles have a carbon weight ratio in the range of 0.001% to 5% by weight.

5. The cerium oxide particles according to claim 4, characterized in that the roughness index RI is at least 3.

5.

6. The cerium oxide particles according to claim 4 or 5, characterized in that the carbon weight ratio of the particles is in the range of 0.1% by weight to 2.5% by weight.

7. The specific surface area of ​​the aforementioned particles is 15 to 100 m². ２ Cerium oxide particles according to any one of claims 4 to 6, characterized in that they are contained within the range of / g.

8. The specific surface area of ​​the aforementioned particles is 20 to 40 m². ２ The cerium oxide particles according to claim 7, characterized by being contained within the range of / g.

9. The cerium oxide particles according to any one of claims 4 to 8, characterized in that the average size of the particles is 30 to 500 nm, and the average size is measured from a TEM image.

10. The cerium oxide particles according to claim 9, characterized in that the average size of the particles is between 140 and 300 nm, and the average size is measured from a TEM image.

11. A dispersion of cerium oxide particles in a liquid medium according to any one of claims 4 to 10.

12. Use of cerium oxide particles according to any one of claims 4 to 10 or the dispersion according to claim 11 for preparing an abrasive composition.

13. A polishing composition comprising cerium oxide particles according to any one of claims 4 to 10 or the dispersion according to claim 11.

14. A method for removing a portion of a substrate, comprising polishing the substrate with the polishing composition described in claim 13.

Images