TW201041805A - Method for preparing ceria powder and slurry composition having the same - Google Patents

Abstract

A method for preparing cerium oxide powder and a slurry composition having the same are disclosed. The slurry composition has a high polishing speed and a high polishing selectivity, and also reduces micro scratches in a chemical mechanical polishing process. The method for preparing cerium oxide powder includes the steps of: rapidly heating a cerium compound to the temperature of 700 to 1,000 DEG C; calcining the cerium compound at the temperature of 700 to 1,000 DEG C to form calcined cerium oxide; and rapidly cooling the calcined cerium oxide to the temperature of 15 to 30 DEG C. Preferably, the step of calcining the cerium compound is carried out for 10 minutes to 2 hours, in the rapid heating step, the cerium compound is heated with a heating speed of 20 to 900 DEG C/min, and, in the rapid cooling step, the calcined cerium oxide is cooled with a cooling speed of 20 to 400 DEG C/min.

Description

201041805 VI. INSTRUCTIONS: All of Neigu is hereby incorporated by reference. This application claims priority to Korean Patent Application, which is filed on May 20, 2009, No. 10-2009-0043970, 20 TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for preparing a cerium oxide (-) powder, and a slurry composition having the cerium oxide powder. The polymeric composition of the present invention has high milling speeds and high milling selectivity and also reduces micro-scratches in the CMP process. [Prior Art] When the degree of integration of the semiconductor element is increased, the margin for the high-precision exposure process for producing 70 parts of the semiconductor body must be introduced into the overall planarization process. The chemical mechanical polishing (CMP) process is generally used for the overall planarization of semiconductor components, and its flatness in 胄"" is superior to other planarization methods, and the process is relatively simple. The abrasive slurry composition used in the CMP process generally includes abrasive particles, deionized water, and various additives. Representative examples of abrasive particles include colloidal ceria particles and smoked particles. However, since the conventional abrasive particles have a low polishing rate for the oxide layer and a low polishing selectivity between the oxide layer and the nitride layer, the conventional abrasive particles cannot be fully satisfied by 201041805, and therefore, the Lingying extra process is Obtain the result of period f. In order to solve such defects, a slurry composition using cerium oxide particles has been developed. The cerium oxide particles are substantially 5|, ^ s v have been used to treat glass products. It is also recognized that the composition of the cerium oxide particles is improved, and the surface composition improves the polishing rate of the oxide layer and the deficiency of the oxide layer and the nitride layer, and the density of the oxidized particles is smaller than that of the diced particles. In terms of high/6 to 8 times, it degrades the dispersion properties of the dip composition. Furthermore, the yttrium oxide particles are susceptible to CMP processes; they can cause undesirable micro scratches on the abrasive substrate.牯

In the STI (Shallow Trench Isolation) CMP process, the depth of the channel is % of 漤. Therefore, the micro-scratches formed during the STI CMP process will be severely inferior—deterioration + quality and yield of the conductor components. The formation of micro-to-marks is known as - defying the size and shape of the abrasive particles. Granules: A method for preparing oxidized granules and a CMP composition comprising the oxidizing sifter is disclosed in Korean Patent Publication No. 0087037 (International Application No. WO 2000/39843). The disclosed patents disclose the desired properties of the abrasive particles for the STICMP paste composition as well as the desired additives. At the same time, in the national patent, the slurry composition is aged to reduce the formation of micro scratches. In 1 〇 良 In Korean Patent Publication No. 02-0009619 (International φ 軎安 & A 凊 诡: WO 2000/73211), 露-species method for preparing cerium oxide particles according to heating rate. However, the 弁&, 卞 method used to make cerium oxide particles does not fully satisfy the problem of reducing micro-scratches derived from oxidized scorpions. 5 201041805 [Summary content]

Accordingly, it is an object of the present invention to provide a method for preparing a ceria powder, and a 'hyperbum composition having the cerium oxide powder, which has high polishing speed and high polishing selectivity, and Reduce micro-marks in the chemical mechanical polishing process. Another object of the present invention is to provide a method for preparing cerium oxide powder, and a cerium composition having the oxidized powder, which is particularly suitable for use in an STI (Shallow Channel Isolation) CMP process. In order to achieve the above objectives, the present invention provides a method for preparing cerium oxide powder, and the method includes the following steps: rapidly heating a hydrazine compound to a temperature of 700 C to looot; and submerging the koji at a temperature of 7 〇〇ul〇〇〇t^ To form a pseudo-sintered yttrium oxide; and to rapidly cool the yttrium-doped yttrium oxide to a temperature of 15 c to 30 C. Preferably, the step of calcining the ruthenium compound is carried out for 10 minutes to 2 hours. In the rapid heating step, the decorative compound is heated at a heating rate of 20 ° C / min to 90 (TC / min, and in the rapid cooling step煆 钸 钸 钸 钸 2 2 2 2 2 2 2 rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc rc The weight percentage is 〇1% to 10% of cerium oxide particles; and the weight percentage is 2 ❶/. to 201⁄4 based on the weight of the cerium oxide particles; and a balanced amount of water. The method of yttrium oxide powder is produced by rapid heating and rapid cooling during the sinter firing process to produce micro-cracks on the surface of cerium oxide particles 6 201041805 (abrasive grains... which are produced: surface and low particle density, and are susceptible to external Breaking and breaking;:: Pressure-sensitive abrasive particles are easily broken by external pressure during the wafer grinding process', thus reducing the formation of micro-scratches on the abrasive surface. The abrasive particles also occur in the polished wafer. Therefore, the product has a high research And (iv) selected from ancient polishing speed of the slurry is set out

It also asks for grinding selectivity and is especially suitable for STI (Shallow Trench Isolation) CMP processes. [Embodiment] The more complete value of the present invention and its many notable advantages can be better understood by referring to the following detailed description. The method for preparing an oxidized decorative powder of the present invention comprises the steps of: rapidly heating a sieve compound S 7 〇〇 U 1 〇〇 (temperature of rc (preferably 750 ° C to 95 (rc); at 700 ° C to 100 (the temperature of TC (preferably 750 C to 950 ° C) sinters the bismuth compound to form bismuth oxide ruthenium; and rapidly cools the bismuth-fired zinc oxide i 15U 30. (: temperature, Preferably, it is preferably from 18 c to 28 c', preferably room temperature (25). The term "fake-burning" means a heat treatment process in which a material is heated at a high temperature to completely or partially remove volatile components of the material. In the present invention, the ruthenium compound is converted into ruthenium oxide (abrasive particles) by calcination. For example, by calcination, carbon monoxide (C〇2) and water (H20) from cesium carbonate (Ce2(c〇3) 3. 6H2〇) is removed to produce cerium oxide (2Ce 〇 2 ). In the present invention, the sinter temperature can be changed according to the type of the cerium compound 7 201041805 ' and it is about 700 ° C to about 100 (TC Preferably, it is about 750 in Duda. (: to about 950 ° C. Preferably, the step of calcining the compound is carried out for a period of from 10 minutes to 2 hours, preferably 15 minutes. 90 minutes (嘏V version magic time). If the simmering time is less than Π) minutes, the sinter compound will be incomplete and the oxidized decoration will be formed in an improper way. If the simmering time exceeds 2 hours, the produced The degree of consolidation of yttrium oxide will increase excessively, and a solid length of 0 77 solid emulsified enamel will form scratches on the abrasive surface (such as wafers), and will be π, # R and it is economically undesired. If the calcination temperature is not within the above range, the calcination of the antimony compound may be performed incompletely or excessively, and the antimony oxide will not have the desired properties. If the rapid cooling temperature is not within the above range, the microcracks may be improperly formed in the oxide decoration. On the surface of the particle.

Preferably, in the rapid heating step, the cerium compound is heated at a rate of from 2 Cc to 30 cc, preferably from 50 t/min to 5%, preferably from 50 t/min to 5 Torr. It is heated at 18 C to 28 ° C, more preferably at room temperature (25 ° C.) In the rapid cooling step, the cerium oxide is enthalpy of 2 〇 <> c / min to 400 ° C / min, preferably It is cooled at a cooling rate of 2 〇ΐ / min to 1 〇 (rc / min.) If the deceleration heating rate is not within the above range, yttrium oxide may be formed incompletely, or micro-cracks may be insufficiently formed on the surface of the cerium oxide particles. If the rapid cooling rate is not within the above range, microcracks may be insufficiently formed on the surface of the cerium oxide particles. In the present invention, the rapid heating step, the calcining step, and the rapid cooling step are performed at least once, preferably repeating. Execute more than one time, especially 2 or 3. For the repeated heating step, the calcining step and the rapid cooling step, the surface of the cerium oxide particles becomes more irregular, and the particle density of the 201041805 cerium oxide particles is further reduced. And cerium oxide particles can be more easily destroyed by external impact. A conventional cerium compound which produces cerium oxide can be used as the cerium compound of the present invention. A preferred example of the cerium compound may be selected from the group consisting of cerium carbonate, cerium hydroxide, cerium sulfate, cerium oxalate, and mixtures thereof. It is barium carbonate.

The ruthenium oxide m diffraction pattern prepared by the t method of the present invention shows a - main peak having a Θ value of 27. To 30. And a peak with a value of 3〇 to 35. The intensity ratio (area ratio, main peak/secondary peak) of the main peak and the secondary peak is equal to or more than 3.0. The cerium oxide powder (particles) has an average particle size of from 2 Å to 50 nm, preferably from 25 to 45 Å. To calculate the particle (crystal) size of the cerium oxide powder, the full width at half maximum (FWHM) value of the main peak determined by the dioptric diffraction analysis of the cerium oxide powder can be combined by the equation (10)(10). The particle size of the cerium oxide powder is small; m is the deterioration of the polishing rate and the polishing selectivity in the CMP process. If the particle size of the cerium oxide powder exceeds 5 ,, a slight trace will be formed on the polished surface in the cMp process. The mass composition of the present invention comprises oxidized particles, and is particularly suitable for use in micro-scratches, which will be strictly controlled by the second-instance, and the quality and productivity of the beef conductors.

In the Mp process. The slurry composition of the present invention comprises: based on the total weight of the mass composition, the weight percentage is up to iq% (preferably 〇5% to 5%\ of zinc oxide particles and based on the weight of the cerium oxide particles) (i.e., the weight of the cerium oxide particles & (10)%), the weight percentage of the dispersant to: preferably 3% to 15% by weight; and the balance of purchased water 'preferably deionized water or pure If the amount of oxidized particles 201041805 is less than the weight percentage 〇J 0/〇私 2 ή, the emulsified cerium particles are not enough to work like abrasive particles, which will deteriorate the enthalpy and grinding selectivity. If the amount exceeds the weight percentage, if the right oxime is 10°/, the cerium oxide particles will accumulate votes, form a crystal cluster or sink the temple, which will continue to separate the composition phase of the / 礴 礴 礴Separation, and further progress to promote the formation of microscopic marks in the CMP process. ο ο In the composition of the present invention, a dispersing agent is added to uniformly disperse the abrasive particles in the slurry composition. For the agent, a dispersing agent conventionally used for the CMP slurry composition can be used. Examples of the dispersing agent of the present invention may include carbonic acid or a salt thereof. Preferred dispersing agents are many: 'or a salt thereof, and the most preferred dispersing agent is acrylic acid or a salt thereof, such as an ammonium salt of polyacrylic acid. Specific examples of carbonic acid include: glutaric acid, gluconic acid, glycolic acid, lauric acid, lactic acid, frequency acid, malonic acid, citric acid, citric acid, stearic acid, succinic acid, acetic acid, oxalic acid, hexane Acid, citric acid, caproic acid, octanoic acid, formic acid, butenedioic acid, phthalic acid, propionic acid, propionic acid, tartaric acid, polyacrylic acid, salts thereof, mixtures thereof, etc. Carbonates include conventional salts, For example, a sodium salt, an ammonium salt, a potassium salt, etc. As the dispersing agent, at least one carbonic acid or a salt thereof can be used. When the dispersing agent is a polycarboxylic acid, the weight average molecular weight of the dispersing agent is from 5,000 to 20,000, preferably 10,000. To 15000. If the weight average molecular weight of the dispersant is less than 5 〇〇〇 or more than 20,000', the dispersion of the slurry composition may be insufficient. If the amount of the dispersant is less than 2% by weight (based on the weight of the cerium oxide particles) )' cerium oxide in the slurry composition Dispersion is insufficient, and it will collect, form crystal clusters or precipitate. If the amount of dispersant exceeds 20% by weight (based on the weight of cerium oxide particles), the excess dispersant will become miscellaneous 10 201041805 and it does not have any Additional advantages ❹ An oxidized decorative composition can be prepared by adding cerium oxide particles and a dispersing agent to water. When the dispersed oxidized particles are in water, the dispersing device can be used to prevent aggregation of cerium oxide particles in the slurry composition. Conventional agitators or dispersing devices are used as dispersing devices. Specific examples of dispersing devices include: vibrators, homogenizers, paint shakers, ultrasonic homogenizers, bead mills, roll mills, top mills (apexmill), Vibratory ball mills, combinations thereof. In the case of using a bead mill, conventional beads such as cerium oxide beads, alumina beads, glass beads, and the like can be used as the dispersion. Hereinafter, preferred examples and comparative examples are provided to facilitate the understanding of the present invention. However, the invention is not limited to the following examples. [Example 1] Preparation of cerium oxide 3 () g of cerium carbonate powder in a tumbling bowl at room temperature (251) was slowly pushed into a tubular furnace of 7 〇 rc (steaming temperature). When the bowl is pushed, the movement speed of the bowl is controlled so that the heating rate of the strontium carbonate powder is ι 〇〇 c / min. When the temperature of the barium carbonate powder is increased to the temperature of the calcination () hour. Then, the bowl was moved into the dryer ' and the sintered yttria was cooled to the chamber S (cooling rate: 500 c / knife) to obtain a color-transparent powder. The cooling rate can be adjusted by controlling the temperature of the cooling water surrounding the dryer. By x-ray diffraction analysis, it was confirmed that the yellow umbrella blade was yttrium oxide. The half-height width (FWHM) of the main peak of the oxidized powder in the X-ray diffraction pattern and the Scherrer equation are used to smear the oxidized particles 201041805 '=particle size, which is about 28 nm (Table 1). The TEM (transmissive electron microscope) image of the cerium oxide powder produced in Example j shows 1 image. , [聋 聋 Example 2 to 4] Preparation of cerium oxide. In addition to changing the calcination temperature from 70 (rc to 8〇〇r (example 2), 9〇〇 C: example 3) and 1〇〇 (rc (example 4), the yellow powder is root

Prepared by the method of Example 1. By calender diffraction analysis, it can be confirmed that the yellow color is yttrium oxide. The flat particle size of the cerium oxide particles was determined according to the method of Example 1, which is presented in Table 1. The #饰奋ΤΕΜ (transmission electron microscope) images produced in Examples 2 to 4 are shown in the first to fourth figures. [Examples 5 to 8] Preparation of cerium oxide except for changing the calcination temperature from 70 (rc to 9 〇 (rc and changing the heating rate 100 from 100 C / min to 2 〇 ° C / min (example 5), 50 °) In addition to c / min (example 6), 〇 C / knife (example 7) and 9 〇 (rc / min (example 8), yellow powder 2 was prepared according to the method of Example 1. By X-ray diffraction analysis, it was confirmed ^Color-only powder is cerium oxide. The average particle size of cerium oxide particles was determined according to the method of Example i, which is presented in Table 1. The TEM (transmissive electron microscope) image of cerium oxide powder produced in Examples 5 to 8 shows 5 to 8 circles. [Example 9 to U] Preparation of yttrium oxide 12 201041805 In addition to changing the temperature of simmering from 70 (TC to 900 ° C, the heating rate is changed from l 〇〇 ° C / min to 45 (TC/min, and the cooling rate from 5 (rc/min to 20 °C/min (example 9), 100 y/min (example 1 〇) and 200 t/min (example 11), the yellow powder is Prepared according to the method of Example 1. It was confirmed by X-ray diffraction analysis that the yellow powder was cerium oxide. The average particle size of the cerium oxide particles was determined according to the method of Example 1, which is long in Table i: Example 9 to 1 The TEM (transmission electron microscope) image of the oxidized powder produced in 1 is shown in Fig. 9 to Fig. u. [Example 12] The preparation of yttrium oxide was changed from 7 G (rc to 9 (10). Change the heating rate from l〇〇C/min to 45 (rc/min, change the simmering time from ! hours to 3: minutes and further perform the heating step, the smoldering step and the cooling again

* The smear powder was prepared according to the method of Example 1. It was confirmed by X 〇 m 'the yellow powder was an oxidized decoration. According to the example! The yttrium oxide powder produced by the average particle size of the rolled ruthenium particles is shown in Fig. 12. [Example 13] The preparation of cerium oxide was carried out except that the calcination time was changed from 3 Torr to 2 〇 minutes and further heated to AL ^ 2 times more than Example 1. The analysis of the vibration and burning steps and the cooling step: = is: 2 1 "2 method preparation. By X-ray diffraction ° wh is oxygen (4). According to the method of Example 1, bee 13 201041805 determines the average particle size of the oxidized town particles, which is presented in Table 1. The yttrium oxide powder yttrium (transmissive electron microscope) pattern produced in Example 13 is shown in Fig. 13. [Example I4] Preparation of cerium oxide except that the smoldering time was changed from 30 minutes to 15 minutes and further than Example 1 In addition to the heating step, the material step and the cooling step, the yellow powder was prepared according to the method of Example 12. It was confirmed by X-ray diffraction analysis that the yellow powder was cerium oxide. The cerium oxide was determined according to the method of the example 丨. The average particle size of the particles is presented in the table. The TEM (transmissive electron microscope) image of the cerium oxide powder produced in Example 14 is shown in Figure 14. [Comparative Example 1] Preparation of cerium oxide will be Platinum at room temperature (251) The 30 g of strontium carbonate powder was slowly pushed into a tubular furnace at 900 ° C (baked temperature). When the platinum bowl was pushed, the movement speed of the bowl was controlled so that the heating rate of the strontium carbonate powder was 1 (rc / min. When the temperature of the barium carbonate powder is increased to the calcination temperature (9 ° C ), the barium carbonate powder is calcined at 90 °C for 1 hour. Then, the calcined barium oxide is cooled to room temperature in a tubular furnace ( Cooling rate: i 〇〇C / min) to obtain a yellow powder. It was confirmed by X-ray diffraction analysis that the yellow powder was cerium oxide. The average particle size of cerium oxide particles was determined according to the method of Example 1, which is shown in Table 1. The TEM (transmission electron microscope) image of the cerium oxide powder produced in Comparative Example i is shown in Fig. 15. 201041805

Table 1 Conditions for preparing yttrium oxide Heating rate (〇C/min) Sintering temperature (°c) Sintering time (minutes) Cooling rate (〇C/min) Additional heating/cooling average particle size (nm) Example 1 100 700 60 50 28 Example 2 800 30 Example 3 900 36 Example 4 1000 42 Example 5 20 900 36 Example 6 50 35 Example 7 450 31 Example 8 900 29 Example 9 450 20 31 Example 10 100 38 Example 11 200 39 Example 12 30 50 1 Example 35 Example 13 20 2 times 34 Example 14 15 3 times 33 Comparative Example 1 10 60 10 44 [Examples 1 5 to 28 and Comparative Example 2] Preparation and evaluation of cerium oxide slurry composition in a premixed container Add 1.5 kg of deionized water and 1.05 g of ammonium polyacrylate and mix. Then, 15 g of the cerium oxide powders prepared in Examples 1 to 14 and Comparative Example 1 were individually added to the mixture. The mixture was dispersed in a bead mill using oxidized hammer beads for 30 minutes to produce a cerium oxide slurry composition (Examples 15 to 28 and 15 201041805 Comparative Example 2). The slurry composition was evaluated as a complete tantalum wafer (8 inches in diameter) having a tantalum oxide layer (thickness: 丨〇μπι) and a complete tantalum wafer (8 inches in diameter) having a tantalum nitride layer as an example 15 to 2 8 and each of the slurry compositions of Comparative Example 2 were ground with an IPEC AVANTI 472 grinding apparatus of Entrepix, Inc., USA. The ruthenium dioxide layer was prepared by TEOS (electrodesulfide)-plasma CVD (chemical vapor deposition) method, and the tantalum nitride layer was prepared by a low pressure CVD method. The grind head pressure of 4 psi, the machine speed of 6 rpm, the head speed of 50 rPm, and the flow rate of 15 〇 cc/min were performed for the test =! minutes. After grinding, the wafer was rinsed with deionized water and dried. The optical interferometer was used to measure the cerium oxide layer and the tantalum nitride layer remaining on the wafer at 2 degrees to determine the polishing rate of the cerium oxide layer and the cerium nitride layer, as shown in Table 2. A micro-to-mark ’ number between 0.3 (4) and 2 5 _ was also measured, which is also presented in Table 2. Evaluation ~~~ Grinding of the oxide layer of the oxide layer --.......degree (A/min) speed (A / min) Example of micro-scratch number 15 ~~-.... .. —· 2845 57 —~~__ 54 Example 16 3194 72 Γ ^ 61 16 201041805

Example 17 3318 81 63 Example 18 3452 102 72 Example 19 3128 74 65 Example 20 3217 65 67 Example 21 3026 57 48 Example 22 2766 51 71 Example 23 3157 81 66 Example 24 3311 48 52 Example 25 2631 50 75 Example 26 3411 55 45 Example 27 3215 53 37 Example 28 3029 49 36 Comparative Example 2 2455 107 176 As shown in Table 2, the oxide composition of the present invention is compared with the slurry composition having the conventional cerium oxide particles (Comparative Example 1) The slurry composition of the particles (Examples 1 to 14) has a high oxide layer polishing rate and a relatively low nitride layer polishing rate, and has a high polishing selectivity between the oxide layer and the nitride layer. Further, as shown in Figs. 1 to 14, the cerium oxide particles of the present invention have a multi-directional, irregular and dimmed lattice 17 201041805 pattern. This irregular lattice pattern is formed by microcracks on the surface of the cerium oxide particles, which are generated by controlling the heating rate and the cooling rate. The cerium oxide abrasive particles of the present invention are susceptible to cracking by external pressure during the grinding process, which reduces the generation of micro scratches on the abrasive layer. Cracked abrasive particles also occur in the grinding of the wafer. Therefore, the slurry of the present invention has a high polishing rate and high polishing selectivity, and is particularly suitable for use in an STI (Shallow Trench Isolation) CMP process. From Example 2 1 (Example 7) and Examples 26 to 28 (Examples 12 to 14), by further performing the heating step and the cooling step more than once, the polishing rate of the slurry composition on the oxide layer is increased, and the nitride is added. The polishing rate of the layer is reduced and the number of micro scratches is reduced. When comparing Fig. 7 and Figs. 12 to 14, the lattice pattern of the abrasive particles in Figs. 12 to 14 is more irregular than the lattice pattern of the abrasive particles in Fig. 7. This difference is due to the fact that the micro-cracks formed on the abrasive particles are increased by repeating the rapid heating step and the rapid cooling step by preparing the cerium oxide abrasive particles. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 14 are TEM photographs of cerium oxide particles individually produced by Examples 1 to 4 of the present invention. Fig. 15 is a photograph of a tem of cerium oxide particles produced in Comparative Example 1. [Main component symbol description] 201041805

Claims (1)

201041805 VII. Patent Application Range: 1. A method for preparing cerium oxide powder, comprising the steps of: rapidly heating a compound to a temperature of 700 ° C to 1 ;; at 700 C to 1000 C The ruthenium compound is calcined to form a pseudo-fired ruthenium oxide; and the bismuth oxide ruthenium is rapidly cooled to a temperature of from 15 t to 30 °C. 2. The method for preparing a cerium oxide powder according to claim 1, wherein the step of calcining the cerium compound is performed for 1 minute to 2 hours, and in the rapid heating step, the cerium compound is 2 (rc / min to 9 〇〇 it / heating at a heating rate, and in the rapid cooling step, the bismuth oxide enthalpy is cooled at a cooling rate of 20 〇 / min to 4 〇〇 ° C / min 3. The method for preparing a cerium oxide powder according to the above item, wherein the rapid heating step, the calcining step, and the rapid cooling step are performed more than once. 4. If the claim is the first item The method for preparing a cerium oxide powder, wherein the cerium compound is selected from the group consisting of cerium carbonate, cerium hydroxide, cerium sulfate, cerium oxalate, and mixtures thereof. Slurry composition 'comprising: cerium oxide particles having a percentage by weight of 0.1% to 1 〇〇 / 〇 20 201041805 based on the total weight of the slurry composition; based on the weight of the cerium oxide particles, the weight percentage is 2% to 20% of the dispersant; Measured water, where 'the cerium oxide particles are prepared by a method comprising the steps of: rapidly heating a compound up to 700 ° C to 1 〇〇〇. (: temperature; at 700. (: to 1000. (: The ruthenium compound is calcined to form a bismuth oxide ruthenium; and the bismuth oxide ruthenium is rapidly cooled to a temperature of from 5 ° C to 30 °. twenty one