A spherical composite cerium oxide, a polishing material and a preparation method thereof

Abstract

The present invention discloses a spherical composite cerium oxide, a polishing material and a preparation method thereof. It relates to the technical field of polishing materials. The above-mentioned spherical composite cerium oxide has raw materials including the following components: a cerium source; ammonia water; an ammonium source; an organic acid; nitric acid; water; the D50 of the above-mentioned spherical composite cerium oxide is 20-160 nm; the molar ratio of the above-mentioned ammonia water to the ammonium source is 1:0.2-0.4. The above-mentioned spherical composite cerium oxide of the present invention has regular shape, uniform concentration, good crystallinity, high purity and few impurities, and can be widely applied to fields such as semiconductor polishing, high-end optical polishing and cosmetics.

Description

Technical Field

[0001] The present invention relates to the technical field of polishing materials, and in particular to a spherical composite cerium oxide, a polishing material and a preparation method thereof. Background Art

[0002] Cerium oxide is a rare earth metal oxide with wide applications, having excellent chemical stability, high-temperature oxidation resistance and strong adsorption capacity, and is widely used in multiple fields such as catalysts, optical materials, batteries and polishing materials. As an important rare earth compound, cerium oxide has various special physical and chemical properties, especially its ability to convert between different oxidation states (Ce 4 ⁺ and Ce³⁺), which enables it to exhibit good catalytic performance in catalytic reactions. In addition, cerium oxide has strong thermal stability and chemical stability, and can still maintain its good performance under high-temperature and high-pressure environments, thus becoming an important component of some high-performance materials.

[0003] Spherical cerium oxide is a specific form of cerium oxide, and its main feature is that its particles exhibit a regular spherical structure. Compared with traditional particle morphologies, spherical cerium oxide has a more uniform particle distribution and better fluidity. Spherical cerium oxide not only has good polishing performance, but also can improve the working efficiency to a certain extent and reduce the possible damage to the semiconductor surface during the polishing process. These characteristics make spherical cerium oxide particularly widely used in the semiconductor industry, especially as a polishing material in the semiconductor wafer polishing process, playing a role in removing surface defects and improving surface flatness.

[0004] Semiconductor polishing is a crucial process in the semiconductor manufacturing process, and its purpose is to improve the flatness and smoothness of the wafer surface by removing minute defects, impurity layers or oxide layers on the wafer surface. In this process, the selection of the polishing material is crucial because it directly relates to the quality of the polishing effect. Spherical cerium oxide, as a commonly used polishing material, is widely used due to its excellent chemical properties and physical characteristics. First, the hardness of cerium oxide is moderate, which can effectively remove minute defects on the silicon wafer surface without excessive wear on the surface. Second, due to the spherical structure of the particles of spherical cerium oxide, it can be evenly distributed during the polishing process, providing a more uniform polishing force, thus effectively reducing local over-polishing and surface non-uniformity. Third, the surface activity of the particles of spherical cerium oxide is relatively high, and a good chemical reaction can occur when it contacts the semiconductor surface, which helps to remove contaminants and improve the surface quality.

[0005] However, existing spherical cerium oxide often faces problems of low crystallinity and purity during the production process, which affect its performance. First, spherical cerium oxide with low crystallinity has more amorphous phase regions, which usually lack the typical crystal structure of cerium oxide, making it impossible to perform optimally in some applications. In polishing applications, cerium oxide particles with low crystallinity often show poor stability and low polishing efficiency, which has a certain negative impact on its performance.

[0006] Secondly, the purity of existing spherical cerium oxide is usually unsatisfactory. Cerium oxide with low purity often contains more impurity elements, which may come from impurities in the raw materials or other ingredients added during the production process. The presence of impurities not only affects the catalytic performance of cerium oxide, but also may affect its effect as a polishing material. Certain impurities may react with the surface of the semiconductor during the polishing process, resulting in surface contamination or incomplete reaction, thereby affecting the polishing quality. In addition, the presence of impurities may also cause the chemical stability of spherical cerium oxide to decrease, resulting in failure or performance degradation during use.

[0007] Surface defects are another common problem in the production process of spherical cerium oxide. During the production process of spherical cerium oxide, especially during high-temperature calcination or other heat treatment processes, microcracks or other defects may occur on the surface of spherical cerium oxide due to the influence of factors such as atmosphere, temperature, and time. These defects will not only affect the overall strength of spherical cerium oxide, but also affect its application effect during the polishing process. The presence of surface defects may lead to a weakening of the bonding force between particles, thereby affecting the stability of the particles and further affecting the effect of the polishing process.

[0008] In general, the existing spherical cerium oxide has insufficient crystallinity, purity and surface quality, which limits its application in some high-precision fields. In order to meet the growing demand, improving the crystallinity, purity and surface quality of spherical cerium oxide has become the focus of research. Summary of the invention

[0009] The object of the present invention is to provide a spherical cerium oxide with good crystallinity, high purity and surface quality.

[0010] A first aspect of the present invention is:

[0011] Provided is a spherical composite cerium oxide.

[0012] A second aspect of the present invention is:

[0013] Provided is a method for preparing spherical composite cerium oxide.

[0014] The third aspect of the present invention is:

[0015] Application of the spherical composite cerium oxide

[0016] The present invention also provides a method for semiconductor polishing using the spherical composite cerium oxide

[0017] Specifically, the technical solution adopted according to the first aspect of the present invention is as follows

[0018] A spherical composite cerium oxide, the preparation raw materials comprising the following components

[0019] Cerium source

[0020] Ammonia water

[0021] Ammonium source

[0022] Organic acid

[0023] Nitric acid

[0024] Water

[0025] The D50 of the spherical composite cerium oxide is 20 - 160 nm

[0026] The molar ratio of the ammonia water to the ammonium source is 1:0.2 - 0.4

[0027] According to the embodiments of the present invention, at least one of the following advantages or beneficial effects is achieved by one of the technical solutions in the technical solutions

[0028] The spherical composite cerium oxide of the present invention has regular shape, uniform concentration, good crystallinity, high purity and few impurities, and can be widely applied to fields such as semiconductor polishing, high - end optical polishing and cosmetics

[0029] Specifically, the addition of ammonia water and ammonium source in the raw materials can enable the cerium ions in the cerium source and other metal ions to be effectively coordinated and arranged, promote the directional growth of crystals, and form particles with a regular spherical morphology; the amounts of ammonia water and ammonium source will regulate the reaction efficiency in the formation process of the spherical composite cerium oxide. Appropriate amounts can promote the full progress of the reaction, avoid the change of morphology due to insufficient reaction, and also avoid the increase of impurity content due to overly intense reaction. By controlling the molar ratio of ammonia water to ammonium source to 1:0.2 - 0.4, the crystallinity of the spherical composite cerium oxide is ≥95, and the impurity content is less than 1 ppm. In addition, the appropriate particle size D50 and low impurity content make the spherical composite cerium oxide more conducive to application in semiconductor polishing

[0030] According to an embodiment of the present invention, the raw materials for preparing the spherical composite cerium oxide further include a praseodymium source and / or a neodymium source. Preferably, the raw materials for preparing the spherical composite cerium oxide further include a praseodymium source and a neodymium source. The praseodymium and / or neodymium rare earth metal ions of the praseodymium and / or neodymium source are in the cerium oxide unit cell together with the cerium ions in the cerium source, which helps to stabilize the lattice structure, reduce impurities in the spherical composite cerium oxide, and promote crystal growth, thereby improving the crystallinity. Higher crystallinity helps to reduce defects. The reaction mechanism of the ammonium source, praseodymium source, and / or neodymium salt includes: the ammonium source, praseodymium source, and / or neodymium salt (denoted as CeX, PrX, and / or NdX) first react with an organic acid (denoted as HR1) and an inorganic acid (denoted as HR2) to form R1CeR2, R1PrR2, and / or R1NdR2. Subsequently, R1CeR2, R1PrR2, and / or R1NdR2 react with ammonia water through a sol-gel reaction to form CeO2, PrO2, and / or NdO2, CO2, N2, and H2O, where CeO2, PrO2, and / or NdO2 are the components of the spherical composite cerium oxide.

[0031] According to an embodiment of the present invention, the molar ratio of cerium ions, praseodymium ions, and neodymium ions in the cerium source, praseodymium source, and neodymium source is 100 - 1000000:1:1.

[0032] According to an embodiment of the present invention, the mass ratio of ammonia water to the ammonium source is 1:0.21 - 0.4. The mass ratio of ammonia water to the ammonium source can control the reaction rate, avoid the particles from being deformed due to too intense reaction, and also avoid the product yield from dropping below 50% due to too slow reaction.

[0033] According to an embodiment of the present invention, the concentration of the ammonia water is 1% - 70% w / w.

[0034] According to an embodiment of the present invention, the D50 of the spherical composite cerium oxide is 90 ± 10 nm.

[0035] According to an embodiment of the present invention, the cerium source includes at least one of cerium nitrate, cerium chloride, cerium sulfate, and cerium carbonate.

[0036] According to an embodiment of the present invention, the ammonium source includes at least one of ammonium nitrate, ammonium phosphate, ammonium sulfate, ammonium acetate, and ammonium chloride.

[0037] According to an embodiment of the present invention, the ammonium source is ammonium nitrate.

[0038] According to an embodiment of the present invention, the praseodymium source includes at least one of praseodymium nitrate, praseodymium chloride, praseodymium sulfate, and praseodymium carbonate; the neodymium source includes at least one of neodymium nitrate, neodymium chloride, neodymium sulfate, and neodymium carbonate.

[0039] According to an embodiment of the present invention, the organic acid includes at least one of formic acid, acetic acid, n-butyric acid, n-caproic acid, and oxalic acid.

[0040] According to an embodiment of the present invention, the organic acid is acetic acid.

[0041] According to an embodiment of the present invention, the inorganic acid is nitric acid. Preferably, when the ammonium source is ammonium nitrate, the organic acid is acetic acid, and the inorganic acid is nitric acid, it can ensure that the product impurities are less than 1 ppm.

[0042] Specifically, the technical solution adopted according to the second aspect of the present invention is as follows:

[0043] A method for preparing the spherical composite cerium oxide includes the following steps:

[0044] S1 Mix the cerium source with water, nitric acid, and organic acid in sequence to obtain a first mixed solution;

[0045] S2 Add ammonia water and ammonium source to the first mixed solution, heat and react to obtain a second mixed solution;

[0046] S3 Adjust the pH of the second mixed solution to be alkaline, and through a sol-gel reaction, obtain the spherical composite cerium oxide;

[0047] In the step S2, the temperature of the heating reaction is 30°C - 120°C, and the time of the heating reaction is 1 - 60 hours.

[0048] According to the embodiment of the present invention, at least one of the following advantages or beneficial effects is possessed by one of the technical solutions in the technical solution:

[0049] The present invention controls the pH to be alkaline, thereby promoting the formation of spherical particles, making the reaction more controllable, and the nucleation and growth of grains more uniform, ensuring the formation of regular nano-spherical composite cerium oxide; when using the sol-gel method, the cerium ions in the second mixed solution form a nano-scale gel network through hydrolysis reaction, and through dehydration and hydrolysis reactions during the sol-gel reaction process, finally transform into uniform nano-particles. The sol-gel method can achieve relatively uniform particle growth and smaller grain size, which helps to control the shape and crystallinity of the material. Appropriate temperature and time can ensure that the spherical composite cerium oxide has high purity and few impurities. When the temperature is too low, the reaction cannot start. When the temperature is too high, the impurities increase, and even the product cannot be formed.

[0050] According to an embodiment of the present invention, the mass ratio of water in the step S1 to ammonia water and ammonium source in the step S2 is 50 - 100:4:2.

[0051] According to an embodiment of the present invention, in the step S1, the volume ratio of nitric acid, organic acid to water is 2:1:100 - 280. A suitable volume ratio of nitric acid, organic acid to water can ensure that the spherical composite cerium oxide has high purity and few impurities.

[0052] According to an embodiment of the present invention, in the step S1, the mass ratio of the cerium source to water is 1:100 - 20000. The mass ratio of the cerium source to water can also adjust the reaction rate. When the ratio of the ammonium source to water is too low, the product will not be formed. When the ratio of the ammonium source to water is too high, the reaction is too fast, resulting in the product being unable to form nanoparticles.

[0053] According to an embodiment of the present invention, in the step S2, the temperature of the heating reaction is 30°C - 85°C.

[0054] According to an embodiment of the present invention, in the step S2, the temperature of the heating reaction is 85°C - 120°C.

[0055] According to an embodiment of the present invention, in the step S2, the heating reaction time is 1 - 120 hours.

[0056] According to an embodiment of the present invention, in the step S2, the heating reaction time is 1 - 60 hours.

[0057] According to an embodiment of the present invention, in the step S2, the heating reaction time is 60 - 120 hours.

[0058] According to an embodiment of the present invention, in the step S3, the pH of the base is 7.0 - 11.0. At other pH values, the particle shape of the spherical composite cerium oxide will change.

[0059] According to an embodiment of the present invention, the method for preparing the spherical composite cerium oxide further includes the following steps:

[0060] A1 Mix the cerium source with water, praseodymium source and / or neodymium source, nitric acid, and organic acid in sequence to obtain a first mixed solution;

[0061] A2 Add ammonia water and ammonium source to the first mixed solution, and heat the reaction to obtain a second mixed solution;

[0062] A3 Adjust the pH of the second mixed solution to be alkaline, and obtain the spherical composite cerium oxide through sol-gel reaction, concentration operation, and centrifugation operation;

[0063] In the step A2, the temperature of the heating reaction is 30°C - 120°C, and the heating reaction time is 1 - 60 hours.

[0064] According to an embodiment of the present invention, in step A3, the following steps are further included: after the second mixed solution undergoes a sol-gel reaction, it is concentrated by high-temperature distillation at 20°C - 160°C to obtain a sol, and the sol is concentrated and centrifuged to obtain the spherical composite cerium oxide.

[0065] According to an embodiment of the present invention, in step A3, after the centrifugation operation, drying and deagglomeration steps are further included.

[0066] According to an embodiment of the present invention, the concentration temperature of the concentration operation is 120°C - 180°C.

[0067] According to an embodiment of the present invention, after the concentration operation, the solid content of the obtained product is ≥60.0%.

[0068] According to an embodiment of the present invention, in step A3, after the centrifugation operation, a drying operation is further included.

[0069] According to an embodiment of the present invention, the temperature of the drying operation is 300°C - 1100°C.

[0070] According to an embodiment of the present invention, the drying time of the drying operation is 2 - 12 hours.

[0071] Another aspect of the present invention further provides a semiconductor polishing material. It includes the spherical cerium oxide composite material as described in the embodiment of the first aspect above. Since this application adopts all the technical solutions of the above spherical cerium oxide composite material, it has at least all the beneficial effects brought by the technical solutions of the above embodiments.

[0072] Another aspect of the present invention further provides a method for semiconductor polishing, including the following steps: fixing the wafer to be polished on a polishing platen, starting the polishing equipment, and preparing the semiconductor polishing material into a polishing liquid and spraying it onto the surface of the polishing pad for polishing.

[0073] According to an embodiment of the present invention, a method for semiconductor polishing includes the following steps:

[0074] Fix the wafer to be polished on a polishing platen, start the polishing equipment, and spray the semiconductor polishing material onto the surfaces of the polishing pad and the wafer for polishing.

[0075] According to an embodiment of the present invention, the semiconductor polishing material is a polishing liquid, and the polishing liquid has the following components in parts by weight:

[0076] Abrasive, 1.5 - 3.0 parts;

[0077] Ultra-pure water, 85.0 - 90.0 parts;

[0078] Oxidizing agent, 0.5 - 1 part;

[0079] Complexing agent, 1.0 - 2.0 parts;

[0080] Corrosion inhibitor, 0.1 - 0.5 part;

[0081] Surfactant, 0.2 - 0.4 part;

[0082] pH regulator, 0.2 - 0.3 part.

[0083] According to an embodiment of the present invention, the abrasive includes the square cerium oxide composite material as described in the embodiment of the first aspect above.

[0084] According to an embodiment of the present invention, the oxidizing agent includes potassium permanganate and / or hydrogen peroxide. The oxidizing agent can promote chemical reactions and accelerate material removal.

[0085] According to an embodiment of the present invention, the complexing agent includes glutamic acid and / or acetyl amino acid. The complexing agent can form complexes, stabilize metal ions in the solution, and prevent their precipitation.

[0086] According to an embodiment of the present invention, the corrosion inhibitor includes ammonia water. The corrosion inhibitor can reduce the corrosion of the areas that do not need to be polished and protect the material surface.

[0087] According to an embodiment of the present invention, the surfactant includes polyacrylic acid ether. The surfactant can reduce the surface tension and improve the wettability and dispersibility of the polishing liquid.

[0088] According to an embodiment of the present invention, the pH regulator includes citrate. The pH regulator can adjust the pH value of the solution and optimize the chemical reaction conditions during the polishing process.

[0089] Other features and advantages of the present invention will be described in the subsequent description of the specification, and some of them will become obvious from the specification or be understood by implementing the present invention. Brief Description of the Drawings

[0090] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0091] Figure 1 It is the flow chart for preparing spherical composite cerium oxide in Example 1.

[0092] Figure 2 It is the SEM image of the spherical composite cerium oxide prepared in Example 1. Detailed Description of the Embodiments

[0093] In the description of the present invention, if the first, second, etc. are described, they are only for the purpose of distinguishing technical features, and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0094] The terms "preferred", "more preferred", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects under certain circumstances. However, in the same circumstances or other circumstances, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0095] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0096] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of the present invention.

[0097] The reagents, methods, and equipment used in the present invention, unless otherwise specified, are all conventional reagents, methods, and equipment in the technical field.

[0098] Example 1

[0099] A spherical composite cerium oxide, the preparation raw materials comprising the following components:

[0100] Cerium source;

[0101] Praseodymium source;

[0102] Neodymium salt;

[0103] Ammonia water;

[0104] Ammonium source;

[0105] Organic acid;

[0106] Nitric acid;

[0107] Water;

[0108] The above cerium source is cerium nitrate;

[0109] The ammonium source described above is ammonium nitrate;

[0110] The organic acid described above is acetic acid;

[0111] The praseodymium source described above is praseodymium nitrate;

[0112] The neodymium salt described above is neodymium nitrate.

[0113] To prepare the above spherical composite cerium oxide, the flow chart is as Figure 1 shown, and the SEM image of the prepared spherical composite cerium oxide is as Figure 2 shown. Specifically, it includes the following steps:

[0114] A1 Dissolve the ammonium source in water, then add the praseodymium source and neodymium salt and stir until a transparent and clear solution is obtained. Among them, the molar ratio of cerium ions, praseodymium ions, and neodymium ions in the cerium source, praseodymium source, and neodymium salt is 80000:1:1, and the mass ratio of the ammonium source to water is 1:200; then successively add nitric acid and acetic acid and stir until a transparent and clear solution is obtained to obtain a first mixed solution. Among them, the volume ratio of nitric acid, acetic acid to water is 2:1:200;

[0115] A2 Add ammonia water and ammonium source to the first mixed solution, and react at 85.0 °C and 20 MPa high pressure for 60 hours to obtain a second mixed solution; among them, the mass ratio of water in step A1 to ammonia water and ammonium source in step A2 is 85:4:2, and the molar ratio of ammonia water and ammonium source is 1:0.21;

[0116] A3 Adjust the pH of the above second mixed solution to 10.0 to obtain colloidal spherical cerium dioxide. Concentrate the cerium dioxide concentration to 5% w / w at 120 °C under high temperature and reduced pressure to obtain colloidal spherical cerium dioxide with a particle size of 80 - 100 nm;

[0117] A4 Concentrate the colloidal spherical cerium dioxide at 145 °C under high pressure to a solid content of 95.0% w / w, then centrifuge to obtain a precipitate. The precipitate is dried at 300 °C for 8 hours, and after deagglomeration, a nano-spherical composite cerium oxide powder with D50 of 90 ± 10 nm is obtained, with a yield > 99% and a total metal impurity content < 1 ppm.

[0118] Example 2

[0119] The difference between Example 2 and Example 1 is that in Example 2, the preparation raw materials do not contain praseodymium source and neodymium salt.

[0120] A spherical cerium oxide, the preparation raw materials include the following components:

[0121] Cerium source;

[0122] Ammonia water;

[0123] Ammonium source;

[0124] Organic acid;

[0125] Nitric acid;

[0126] Water;

[0127] The above cerium source is cerium nitrate;

[0128] The above ammonium source is ammonium nitrate;

[0129] The above organic acid is acetic acid.

[0130] Preparing the above spherical composite cerium oxide includes the following steps:

[0131] A1 Dissolve the ammonium source in water, then sequentially add nitric acid and acetic acid, and stir until a transparent and clear solution is obtained to get a first mixed solution. Among them, the volume ratio of nitric acid, acetic acid to water is 2:1:200;

[0132] A2 Add ammonia water and ammonium source to the first mixed solution, react at 85.0 °C and 20 MPa high pressure for 60 hours to get a second mixed solution; among them, the mass ratio of water to ammonia water and ammonium source is 85:4:2, and the molar ratio of ammonia water and ammonium source is 1:0.21;

[0133] A3 Adjust the pH of the above second mixed solution to 10.0 to obtain colloidal cerium oxide, and concentrate the cerium oxide concentration to 5% w / w at 120 °C under high temperature and reduced pressure to obtain colloidal spherical cerium oxide;

[0134] A4 Concentrate the colloidal spherical cerium oxide to a solid content of 95.0% w / w at 145 °C under high pressure, then centrifuge to obtain a precipitate. The precipitate is dried at 300 °C under high temperature for 8 hours, and after deagglomeration, nano-spherical composite cerium oxide powder with D50 of 90 ± 30 is obtained, the yield is 85%, and the total metal impurity content is <100 ppm.

[0135] Example 3

[0136] The difference between Example 3 and Example 1 is that in Example 3, the molar ratio of ammonia water and ammonium source is 1:0.4.

[0137] A spherical composite cerium oxide, the preparation raw materials include the following components:

[0138] Cerium source;

[0139] Praseodymium source;

[0140] Neodymium salt;

[0141] Ammonia water;

[0142] Ammonium source;

[0143] Organic acid;

[0144] Nitric acid;

[0145] Water;

[0146] The above cerium source is cerium nitrate;

[0147] The above ammonium source is ammonium nitrate;

[0148] The above organic acid is acetic acid;

[0149] The above praseodymium source is praseodymium nitrate;

[0150] The above neodymium salt is neodymium nitrate.

[0151] Preparing the above spherical composite cerium oxide includes the following steps:

[0152] A1 Dissolve the ammonium source in water, then add the praseodymium source and neodymium salt and stir until a transparent and clear solution is obtained. Among them, the molar ratio of cerium ions, praseodymium ions, and neodymium ions in the cerium source, praseodymium source, and neodymium salt is 80000:1:1, and the mass ratio of the ammonium source to water is 1:200; then successively add nitric acid and acetic acid and stir until a transparent and clear solution is obtained to obtain a first mixed solution. Among them, the volume ratio of nitric acid, acetic acid to water is 2:1:200;

[0153] A2 Add ammonia water and ammonium source to the first mixed solution, and react at 85.0 °C and 20 MPa high pressure for 60 hours to obtain a second mixed solution; among them, the mass ratio of water to ammonia water and ammonium source is 85:4:2, and the molar ratio of ammonia water and ammonium source is 1:0.4;

[0154] A3 Adjust the pH of the above second mixed solution to 10.0 to obtain colloidal spherical cerium dioxide, and concentrate the cerium dioxide concentration to 5% w / w at 120 °C under high temperature and reduced pressure to obtain colloidal spherical cerium dioxide;

[0155] A4 Concentrate the colloidal spherical cerium dioxide to a solid content of 95.0% w / w at 145 °C under high pressure, then centrifuge to obtain a precipitate, and dry the precipitate at 300 °C under high temperature for 8 hours. After deagglomeration, a nano-spherical composite cerium oxide powder with D50 of 90 ± 70 nm is obtained, with a yield of 81% and an impurity content < 100 ppm.

[0156] Example 4

[0157] A polishing liquid, having the following components in parts by weight:

[0158] Abrasive, 1.5 parts;

[0159] Ultra-pure water, 85.0 parts;

[0160] Oxidizing agent, 0.5 part;

[0161] Complexing agent, 1.0 part;

[0162] Corrosion inhibitor, 0.1 part;

[0163] Surfactant, 0.2 part;

[0164] pH regulator, 0.2 part.

[0165] Among them, the abrasive is the nano-spherical composite cerium oxide powder prepared in Example 1;

[0166] Among them, the oxidant is potassium permanganate;

[0167] Among them, the complexing agent is glutamic acid;

[0168] Among them, the corrosion inhibitor is ammonia water;

[0169] Among them, the surfactant is polyacrylic acid ether;

[0170] Among them, the pH regulator is citrate.

[0171] Example 5

[0172] A method for semiconductor polishing using the polishing liquid of Example 4, comprising the following steps:

[0173] Check the components such as the polishing pad and polishing disc of the CMP equipment to ensure that they are clean and functioning properly;

[0174] Fix the silicon wafer to be polished on the polishing disc to ensure its firmness;

[0175] Start the equipment, evenly spray the polishing liquid onto the surface of the polishing pad, and start the polishing process;

[0176] After polishing, thoroughly clean the surface of the silicon wafer with deionized water to remove the residual polishing liquid;

[0177] Dry the wafer with nitrogen to prevent water stains from remaining.

[0178] Comparative Example 1

[0179] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the molar ratio of cerium ions to praseodymium ions and neodymium ions in the cerium source, praseodymium source, and neodymium salt is 10:1:1.

[0180] Comparative Example 2

[0181] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the mass ratio of the ammonium source to water is 1:30000.

[0182] Comparative Example 3

[0183] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the mass ratio of the ammonium source to water is 1:50.

[0184] Comparative Example 4

[0185] The difference between Comparative Example 4 and Example 1 is that in step A1 of Comparative Example 4, acetic acid was added first and then nitric acid.

[0186] Comparative Example 5

[0187] The difference between Comparative Example 5 and Example 1 is that in step A1 of Comparative Example 5, only nitric acid was added and no acetic acid was added.

[0188] Comparative Example 6

[0189] The difference between Comparative Example 6 and Example 1 is that in step A1 of Comparative Example 6, only acetic acid was added and no nitric acid was added.

[0190] Comparative Example 7

[0191] The difference between Comparative Example 7 and Example 1 is that in Comparative Example 7, the volume ratio of nitric acid, acetic acid to water was 2:1:75.

[0192] Comparative Example 8

[0193] The difference between Comparative Example 8 and Example 1 is that in Comparative Example 8, the volume ratio of nitric acid, acetic acid to water was 2:1:300.

[0194] Comparative Example 9

[0195] The difference between Comparative Example 9 and Example 1 is that in step A2 of Comparative Example 9, ammonia water was not added.

[0196] Comparative Example 10

[0197] The difference between Comparative Example 10 and Example 1 is that in step A2 of Comparative Example 10, no ammonium source was added.

[0198] Comparative Example 11

[0199] The difference between Comparative Example 11 and Example 1 is that in step A2 of Comparative Example 11, the mass ratio of water to ammonia water and ammonium source was 40:4:2.

[0200] Comparative Example 12

[0201] The difference between Comparative Example 12 and Example 1 is that in step A2 of Comparative Example 12, the mass ratio of water to ammonia water and ammonium source was 120:4:2.

[0202] Comparative Example 13

[0203] The difference between Comparative Example 13 and Example 1 is that in step A2 of Comparative Example 13, the molar ratio of ammonia water to ammonium source was 1:0.005.

[0204] Comparative Example 14

[0205] The difference between Comparative Example 14 and Example 1 is that in step A2 of Comparative Example 14, the reaction temperature is 15.0 °C.

[0206] Comparative Example 15

[0207] The difference between Comparative Example 15 and Example 1 is that in step A2 of Comparative Example 15, the reaction temperature is 170.0 °C.

[0208] Comparative Example 16

[0209] The difference between Comparative Example 16 and Example 1 is that in step A2 of Comparative Example 16, the reaction time is 50 minutes.

[0210] Comparative Example 17

[0211] The difference between Comparative Example 17 and Example 1 is that in step A2 of Comparative Example 17, the reaction time is 120 hours.

[0212] Comparative Example 18

[0213] The difference between Comparative Example 18 and Example 1 is that in step A3 of Comparative Example 18, the pH is adjusted to 6.0.

[0214] Comparative Example 19

[0215] The difference between Comparative Example 19 and Example 1 is that in step A3 of Comparative Example 19, high-temperature vacuum concentration is carried out at 60 °C. If the temperature is too low, concentration cannot be achieved.

[0216] Comparative Example 20

[0217] The difference between Comparative Example 20 and Example 1 is that in step A3 of Comparative Example 20, high-temperature vacuum concentration is carried out at 200 °C. If the temperature is too high, there is a risk of explosion.

[0218] Comparative Example 21

[0219] The difference between Comparative Example 21 and Example 1 is that in step A4 of Comparative Example 21, high-pressure concentration is carried out at 80 °C.

[0220] Due to the too low temperature, the concentration cannot reach the specified concentration.

[0221] Comparative Example 22

[0222] The difference between Comparative Example 22 and Example 1 is that in step A4 of Comparative Example 22, high-pressure concentration is carried out at 200 °C.

[0223] Due to the too high temperature, there is a risk of explosion.

[0224] Comparative Example 23

[0225] The difference between Comparative Example 23 and Example 1 is that in step A4 of Comparative Example 23, drying was carried out at a temperature of 280 °C, and the moisture could not be completely removed.

[0226] Comparative Example 24

[0227] The difference between Comparative Example 24 and Example 1 is that in step A4 of Comparative Example 24, drying was carried out at a temperature of 1200 °C, and the morphology of the product nanoparticles changed and could not maintain a spherical shape.

[0228] Comparative Example 25

[0229] The difference between Comparative Example 25 and Example 1 is that in step A4 of Comparative Example 25, the drying time was adjusted to 1.5 hours, resulting in incomplete removal of moisture.

[0230] Comparative Example 26

[0231] The difference between Comparative Example 26 and Example 1 is that in step A4 of Comparative Example 26, the drying time was adjusted to 12 hours, which was too long, wasted energy, and had an impact on the product morphology.

[0232] Performance test:

[0233] The cerium oxide composite powder prepared in Examples 1-3 and Comparative Examples 1-19 was analyzed, and the analysis results are shown in Table 1.

[0234] Table 1

[0235]

[0236] It can be seen from Table 1 that in Comparative Example 1, the addition amounts of praseodymium ions and neodymium ions relative to cerium ions were too large, resulting in non-shaped particles, larger particle sizes, and more impurities.

[0237] In Example 2, without doping praseodymium and neodymium, the impurity content of the product increased significantly.

[0238] In Example 3, the molar ratio of ammonia water to ammonium source was 1:0.4. The excessive ammonium source would bring extra metal impurities and also affect the reaction rate. Although the product was still spherical nano-composite cerium oxide, its impurity content increased and did not meet the semiconductor application requirements.

[0239] In Comparative Example 2, the mass ratio of ammonium source to water was too low, resulting in an extremely low reaction rate and non-shaped particles.

[0240] In Comparative Example 3, the mass ratio of ammonium source to water was too high, resulting in too fast a reaction rate and inability to form spherical nanoparticles.

[0241] In Comparative Example 4, the addition order of organic acid and nitric acid was changed, resulting in the inability of the reaction to proceed smoothly.

[0242] In Comparative Examples 5-6, no organic acid or nitric acid was added, resulting in the failure of the reaction to proceed smoothly.

[0243] In Comparative Example 7, the volume ratio of nitric acid, acetic acid to water was changed to 2:1:75. The amount of water used was too small, and the particle shape could not be maintained or even formed.

[0244] In Comparative Example 8, the volume ratio of nitric acid, acetic acid to water was changed to 2:1:300. The amount of water used was too large, resulting in the inability to maintain the particle shape, an increase in impurities, a decrease in the reaction rate, and incomplete reaction.

[0245] In Comparative Examples 9-10, due to the addition of less ammonia or ammonium source in Step A2, the reaction efficiency decreased, the reaction was incomplete, and the particle morphology changed.

[0246] In Comparative Example 11, since the mass ratio of water to ammonia and ammonium source was changed to 40:4:2 in Step A2, the reaction was too intense, resulting in the particles not being formed.

[0247] In Comparative Example 12, since the mass ratio of water to ammonia and ammonium source was changed to 120:4:2 in Step A2, the reaction was too slow, resulting in the yield dropping below 50%.

[0248] In Comparative Example 13, since the molar ratio of ammonia and ammonium source was changed to 1:0.005 in Step A2, the reaction was too slow, resulting in incomplete reaction and the particles not being formed.

[0249] In Comparative Example 14, the reaction could not proceed at 15°C.

[0250] In Comparative Example 15, the reaction was carried out at 170°C. The temperature was too high to obtain formed nano-ceria particles.

[0251] In Comparative Example 16, the raw materials were reacted at 85.0°C and 20 MPa for 50 minutes. The time was too short and the reaction was incomplete, resulting in the product not being formed.

[0252] In Comparative Example 17, the raw materials were reacted at 85.0°C and 20 MPa for 120 hours. The time was too long, which not only wasted time, energy and water, but also resulted in the product not being formed.

[0253] In Comparative Example 18, in Step A3, the pH was adjusted to 6.0, resulting in a change in the shape of the product nano-particles.

[0254] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made using the content of the specification of the present invention, or directly or indirectly applied in the relevant technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A spherical composite cerium oxide, characterized in that: The raw materials for preparation include the following components: Cerium source; ammonia; Ammonium source; Organic acids; nitric acid; water; Praseodymium and neodymium sources; The D50 of the spherical composite cerium oxide is 20-160nm; The molar ratio of cerium ions, praseodymium ions and neodymium ions of the cerium source, the praseodymium source and the neodymium source is 100-1000000:1:1; The molar ratio of the ammonia water to the ammonium source is 1:0.2-0.4; The spherical composite cerium oxide is prepared by the following method: S1: mixing a cerium source with water, a praseodymium source, a neodymium source, nitric acid, and an organic acid in sequence to obtain a first mixed solution; S2 adding ammonia water and an ammonium source to the first mixed solution, heating for reaction, and obtaining a second mixed solution; S3: adjusting the pH of the second mixed solution to be alkaline, and obtaining the spherical composite cerium oxide through a sol-gel reaction; In step S2, the heating reaction temperature is 30°C-120°C, and the heating reaction time is 1-60 hours; In the step S1, the mass ratio of the cerium source to water is 1:100-20000; In step S1, the volume ratio of nitric acid, organic acid and water is 2:1:100 - 280; The mass ratio of the water in step S1 to the ammonia water and the ammonium source in step S2 is 50-100:4:

2.

2. The spherical composite cerium oxide according to claim 1, characterized in that: The D50 of the spherical composite cerium oxide is 90±10 nm.

3. A semiconductor polishing material, characterized in that: The invention comprises the spherical composite cerium oxide material as described in any one of claims 1 or 2.

4. A method for polishing a semiconductor, characterized in that: The following steps are involved: The wafer to be polished is fixed on the polishing plate, the polishing equipment is started, the semiconductor polishing material according to claim 3 is prepared into a polishing liquid and then sprayed onto the surface of the polishing pad for polishing.

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