High-stability alumina polishing liquid, preparation method and application thereof

Abstract

The application provides a high-stability alumina polishing liquid and a preparation method thereof. The polishing liquid comprises the following raw material components in mass fraction: 40-60wt% of alumina slurry, 0.1-2wt% of a suspending agent, 0.01-0.1wt% of hydroxyethyl cellulose, 0.001-0.002wt% of a bactericide, the rest being a pH regulator and water; the pH regulator makes the pH value of the polishing liquid 2.0-4.0; the suspending agent comprises xanthan gum and a solvent; and the mass ratio of alumina to water in the alumina slurry is 1:3.5-4.5. The polishing liquid increases the dispersibility stability of the polishing liquid in polishing a PPS material element through the synergistic effect of the homogenization of alumina, the suspending agent and HEC, improves the polishing rate of the polished PPS material element and reduces surface damage.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing technology, and in particular to a method for preparing a highly stable alumina polishing slurry. Background Technology

[0002] In chemical mechanical polishing (CMP) processes, PPS (polyphenylene sulfide) components are frequently used as engineering plastic parts in contact with the polishing slurry and polishing pad due to their good heat resistance, chemical resistance, mechanical strength, and processing performance. These components include CMP retaining rings, retaining rings, limiting rings, and carrier parts. PPS retaining rings are typically used to restrict the wafer's position within the carrier head and are in continuous contact with the polishing pad, polishing slurry, and wafer edge areas during polishing. Therefore, their surface condition, abrasion resistance, and particle release directly affect the stability of the CMP process and the level of wafer defects. Abrasive particles, agglomerated particles, and acidic, alkaline, or oxidizing chemical components in the polishing slurry can cause mechanical scratching, wear, or localized damage to the surface of PPS components, resulting in scratches, grooves, roughened areas, or micro-defects. Especially under prolonged cyclic use or high-pressure polishing conditions, the number and size of scratches on the PPS component surface may further increase, thereby reducing its surface integrity and service life.

[0003] Alumina polishing slurry is a high-performance liquid polishing medium using alumina (Al₂O₃) as an abrasive, widely used in precision machining. Alumina itself possesses advantages such as high hardness, high chemical stability, high temperature resistance, and resistance to acid and alkali corrosion, making it an ideal non-metallic polishing material. In the polishing slurry, alumina is dispersed in water or other solvents in the form of micron- or nano-sized particles, forming a stable suspension system. This liquid form effectively reduces scratches on the workpiece surface while improving polishing efficiency and surface finish.

[0004] Compared to solid alumina grinding balls, grinding slurries are more suitable for automated and continuous production, especially in applications requiring uniform micron- or nanometer-level removal rates, where they offer irreplaceable advantages. With the development of high-end manufacturing, alumina grinding slurries are continuously evolving towards higher purity, smaller particle size, and greater environmental friendliness.

[0005] Most commercially available alumina grinding slurries suffer from insufficient suspension stability. In practical use, problems such as sedimentation, clumping, and stratification often occur due to formula imbalances, improper operation, or environmental factors. During storage, dispersants may precipitate; prolonged standing without stirring; and the use of hard water to prepare the slurry, where calcium and magnesium ions disrupt colloidal stability, all exacerbate sedimentation and stratification. To address this issue, vigorous shaking or thorough stirring with a stirrer is often required before use. For example, ultrasonic dispersion for 10-15 minutes or circulation with a stirring device for 10 minutes is necessary to ensure uniform Al2O3 suspension. This pretreatment is not only time-consuming and labor-intensive but also makes it difficult to guarantee consistent dispersion each time, thus affecting the stability and repeatability of the grinding effect.

[0006] Therefore, in practical applications, the hardness, particle size distribution, particle morphology, and dispersion stability of alumina abrasives directly cause fluctuations in local abrasive concentration and instability in polishing force. This exacerbates scratches, roughening, and other damage to the surface of PPS components, reducing surface integrity and lifespan. Simultaneously, it affects the uniformity of wafer processing and defect control, ultimately compromising the polishing stability of the CMP process. Therefore, there is an urgent need to provide an alumina polishing slurry that combines excellent dispersion stability with ease of use, fundamentally solving the dispersion stability problem of polishing slurries and thereby ensuring the polishing stability of PPS components and wafers in the CMP process. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for preparing a highly stable alumina polishing slurry, which solves the problems of poor suspension, obvious stratification, and the need for vigorous shaking or stirring with a stirrer before use, which is time-consuming and laborious.

[0008] To achieve the above and other related objectives, the present invention provides a method for preparing a highly stable alumina polishing slurry.

[0009] The first aspect of this invention discloses an alumina polishing slurry for polishing PPS material components. The alumina polishing slurry comprises the following raw material components by mass fraction: 40wt%~60wt% alumina slurry, 0.1~2wt% a suspending agent, 0.01~0.1wt% hydroxyethyl cellulose, 0.001~0.002wt% a bactericide, and the balance being a pH adjuster and water. The pH adjuster makes the pH value of the polishing slurry 2.0~4.0. The suspending agent comprises xanthan gum and a solvent. The mass ratio of alumina to water in the alumina slurry is 1:3.5~4.5.

[0010] The mass fraction is calculated based on the total mass of the grinding fluid, and represents the percentage of each component relative to the total mass of the grinding fluid.

[0011] Preferably, the alumina particle size in the alumina slurry is 10~650nm, such as 10nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, or 650nm; D 50 For 200-250nm, D 90 For 430-460nm, D 99 The particle size is 630-660nm; the alumina slurry is obtained by homogenizing alumina and water using a homogenizer. After homogenization, the particle size distribution is more concentrated, which improves the dispersibility in the polishing slurry and the polishing rate of the polishing slurry.

[0012] Considering polishing rate, surface effect, and production cost, preferably, the mass fraction of alumina slurry in the polishing slurry is 40-60 wt%, such as 40 wt%, 45 wt%, 50 wt%, 55 wt%, or 60 wt%. More preferably, the mass fraction of alumina slurry in the polishing slurry is 45 wt%-55 wt%, and most preferably, the mass fraction of alumina slurry in the polishing slurry is 50 wt%.

[0013] Preferably, the mass ratio of alumina to water in the alumina slurry is 1:3.5 to 4.5, such as 1:3.5, 1:4, or 1:4.5. Most preferably, the mass ratio of alumina to water in the alumina slurry is 1:4.

[0014] Considering polishing rate, surface effect, and production cost, preferably, the mass fraction of the suspending agent in the polishing slurry is 0.5~2wt%, such as 0.5wt%, 1wt%, 1.5wt%, or 2wt%. More preferably, the mass fraction of the suspending agent in the polishing slurry is 0.5~1.5wt%, and most preferably, the mass fraction of the suspending agent in the polishing slurry is 1wt%. The suspending agent is used to improve the dispersion stability and dispersion uniformity of the polishing slurry. Excessive addition (e.g., 3wt%) will cause the polishing slurry to become too viscous, resulting in a decrease in the polishing rate.

[0015] Preferably, the mass ratio of xanthan gum to solvent in the suspending agent is 1:(2.5-3.5), such as 1:2.5, 1:3, or 1:3.5. The solvent is used to disperse the xanthan gum. Pre-dispersing the xanthan gum in the solvent to prepare the suspending agent during the preparation of the grinding slurry ensures that the xanthan gum powder is fully wetted and uniformly dispersed in the solvent before being added to the solution for preparing the grinding slurry. This effectively prevents clumping. If the xanthan gum is not pre-dispersed and is directly added to the solution for preparing the grinding slurry, it cannot dissolve effectively, requiring high-speed and long-term stirring, and is also prone to particle agglomeration, resulting in an uneven grinding slurry. More preferably, the mass ratio of xanthan gum to solvent in the suspending agent is 1:3.

[0016] Preferably, the solvent in the suspending agent is selected from one or more of propylene glycol, glycerol, or butylene glycol;

[0017] Preferably, the xanthan gum is prepared as a 0.1 wt% aqueous solution with a viscosity of 500~1000 mPa·s at 25°C, such as 500 mPa·s, 600 mPa·s, 700 mPa·s, 800 mPa·s, 900 mPa·s, or 1000 mPa·s. If the xanthan gum viscosity is too high, the prepared grinding slurry will be too viscous, resulting in a decrease in the grinding rate and an increase in the number of particles adhering to the surface of the polished element after polishing.

[0018] Preferably, the hydroxyethyl cellulose (HEC) has a mass fraction of 0.02~0.1wt%, such as 0.02wt%, 0.04wt%, 0.06wt%, 0.08wt%, or 0.1wt%. HEC acts as a protective agent to improve the polishing effect of the polishing slurry, reduce particle adhesion on the polished surface, and reduce scratches. More preferably, the mass fraction of the HEC is 0.04wt%.

[0019] Preferably, the pH of the grinding slurry is 2-4, such as 2, 2.5, 3, 3.5, or 4, and the pH adjuster is electronic-grade nitric acid. More preferably, the pH of the grinding slurry is 3.5. A pH in the acidic range can maintain the stability of the components in the grinding slurry and also provide a suitable antibacterial environment for the bactericide, thus exerting its antibacterial effect.

[0020] Preferably, the concentration of the bactericide is 0.001~0.002wt%. For example, it can be 0.001wt%, 0.0015wt%, or 0.002wt%. More preferably, the concentration of the bactericide is 0.0015wt%. The bactericide in the grinding fluid can inhibit and kill microorganisms, maintaining the chemical stability, colloidal stability, and performance consistency of the grinding fluid during storage and trial use.

[0021] Preferably, under the conditions of polishing pressure of 1.0 pis, polishing speed of 63 / 57 rpm, polishing fluid flow rate of 250 ml / min, and temperature of 42°C, the polishing rate of the polishing fluid on the PPS material component is 80~150 nm / min, such as 80 nm / min, 90 nm / min, 100 nm / min, 110 nm / min, 120 nm / min, 130 nm / min, 140 nm / min or 150 nm / min.

[0022] Preferably, under the conditions of polishing pressure of 1.0 pis, polishing speed of 63 / 57 rpm, polishing slurry flow rate of 250 ml / min, and temperature of 42°C, the surface roughness Ra of the PPS material component after polishing with the above-mentioned polishing slurry is <3.5 nm. More preferably, the surface roughness Ra is 2.0~3.5 nm, such as 2.0 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, 3.0 nm, 3.2 nm, or 3.5 nm. Even more preferably, the surface roughness Ra is 2.2~3.0 nm.

[0023] Preferably, under the conditions of polishing pressure of 1.0 pis, polishing speed of 63 / 57 rpm, polishing fluid flow rate of 250 ml / min, and temperature of 42°C, the residual particle count on the surface of the PPS material component after polishing with the above polishing fluid is 1 to 20 particles, such as 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 particles.

[0024] More preferably, under the conditions of polishing pressure of 1.0 pis, polishing speed of 63 / 57 rpm, polishing fluid flow rate of 250 ml / min, and temperature of 42°C, the residual particle amount on the surface of the PPS material component after polishing with the above polishing fluid is 1 to 10 particles.

[0025] Preferably, under the conditions of polishing pressure of 1.0 pis, polishing speed of 63 / 57 rpm, polishing fluid flow rate of 250 ml / min, and temperature of 42°C, the number of scratches on the surface of the PPS material component after polishing with the above polishing fluid is 0 to 30, such as 0, 2, 3, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, or 30 scratches.

[0026] Preferably, under the conditions of polishing pressure of 1.0 pis, polishing speed of 63 / 57 rpm, polishing fluid flow rate of 250 ml / min, and temperature of 42°C, the number of scratches on the surface of the PPS material component after polishing with the above polishing fluid is 0~20.

[0027] Preferably, under the conditions of polishing pressure of 1.0 pis, polishing speed of 63 / 57 rpm, polishing fluid flow rate of 250 ml / min, and temperature of 42°C, the number of scratches on the surface of the PPS material component after polishing with the above polishing fluid is 0 to 10.

[0028] Preferably, after the grinding slurry is placed at 25°C for 12 months, the particles are still observed to be a uniform turbid suspension in a transparent container by the naked eye.

[0029] Preferably, the grinding slurry is placed at 25°C for 12 months, and the average particle size increases by 0-3% and the specific gravity increases by 0-1%. For example, the average particle size increase can be 0%, 0.5%, 1%, 1.5%, 2%, 2.5% or 3%; the specific gravity increase can be 0%, 0.2%, 0.4%, 0.6%, 0.8% or 1%.

[0030] Preferably, the total gold impurities (excluding aluminum ions) content of the polishing fluid is 95~150 ppb, such as 95 ppb, 100 ppb, 105 ppb, 110 ppb, 115 ppb, 120 ppb, 125 ppb, 130 ppb, 135 ppb, 140 ppb, 145 ppb or 150 ppb.

[0031] The second aspect of the present invention discloses a method for preparing the above-mentioned alumina polishing slurry, the method comprising: mixing and stirring alumina slurry, water, suspending agent and HEC evenly, adjusting pH, adding bactericide and stirring evenly to obtain polishing slurry.

[0032] To ensure the prepared polishing slurry is more stable and has better polishing rate and dispersibility, the preparation method preferably follows these steps:

[0033] 1) Add water and suspending agent to the alumina slurry and stir evenly to obtain the first mixture; the suspending agent is used to suspend the alumina, so that it can be better mixed with other raw material components in the future.

[0034] 2) Add HEC to the first mixture, stir well, add a pH adjuster to adjust the pH to 2-4, add the bactericide, stir well, and obtain the grinding slurry. The bactericide is acidic; adjusting the pH to the acidic range before adding the bactericide helps maintain its stability and better exert its bactericidal effect.

[0035] Preferably, the method for preparing the alumina slurry includes: mixing alumina and water, stirring until homogenized, and homogenizing using a homogenizer.

[0036] Preferably, the method for preparing the suspending agent includes: mixing the solvent and xanthan gum and stirring until homogeneous.

[0037] Preferably, the alumina slurry is prepared by stirring in two stages. The first stirring speed is 3800-4000 r / min, and the first stirring time is 15-30 min. The second stirring speed is 1900-2000 r / min, and the second stirring time is 15-30 min. More preferably, the first stirring time is 19-21 min, and the second stirring time is 19-21 min.

[0038] Preferably, the pressure of the homogenizer in the preparation of the alumina slurry is 16,000 to 20,000 psi, such as 16,000 psi, 17,000 psi, 18,000 psi, 19,000 psi, or 20,000 psi. More preferably, the pressure is 18,000 psi.

[0039] Preferably, in the preparation of the suspending agent, the rotation speed of propylene glycol before mixing with xanthan gum is 45-55 r / min, such as 45 r / min, 50 r / min, or 55 r / min; the rotation speed after mixing is 175-185 r / min, such as 175 r / min, 180 r / min, or 185 r / min; the stirring time after mixing is 30-60 min, such as 30 min, 40 min, 50 min, or 60 min. Stirring continues until the xanthan gum is completely dissolved. If it is not completely dissolved after 60 min of stirring, the stirring time can be extended until it is completely dissolved.

[0040] Preferably, in step 1), the stirring speed after adding water to the alumina slurry is 45-55 r / min, such as 45 r / min, 50 r / min, or 55 r / min; after adding the suspending agent, the stirring speed is 90-120 r / min, such as 90 r / min, 100 r / min, 110 r / min, or 120 r / min. More preferably, the stirring speed is 98-102 r / min;

[0041] Preferably, the stirring speed during step 2 is 90-120 r / min, such as 90 r / min, 100 r / min, 110 r / min or 120 r / min. More preferably, the stirring speed is 98-102 r / min; even more preferably, the stirring speed is 100 r / min.

[0042] Preferably, the stirring time during step 2 is 10-40 minutes; for example, it can be 10 minutes, 20 minutes, 30 minutes, or 40 minutes. More preferably, the stirring time is 30 minutes.

[0043] A third party to this invention provides an application of the above-mentioned polishing fluid in the polishing of PPS material components.

[0044] Preferably, the polishing slurry reduces the surface roughness of the PPS material element to 2.0~3.5 nm during polishing, such as 2.0 nm, 2.2 nm, 2.5 nm, 2.8 nm, 2.9 nm, 3.0 nm, 3.2 nm or 3.5 nm.

[0045] Preferably, the polishing slurry increases the polishing rate to 80~150 nm / min in the polishing of PPS material components.

[0046] Preferably, the application includes controlling the amount of residual surface particles on the PPS material element after polishing to be 0-20 particles. More preferably, the amount of residual surface particles is 0-10 particles.

[0047] Preferably, the application includes controlling the number of surface scratches on the PPS material element after polishing to be 0-30. More preferably, the number of surface scratches is 0-10.

[0048] The fourth aspect of the present invention provides the use of alumina homogenized by a homogenizer in improving the dispersion stability of grinding slurry.

[0049] As described above, the alumina polishing slurry and its preparation method of the present invention have the following beneficial effects:

[0050] 1. This invention provides an alumina polishing slurry with high polishing rate, low surface particle residue, and low surface scratches. By homogenizing the alumina, the alumina dispersion is increased, thereby improving the polishing rate of PPS material components and reducing surface damage.

[0051] 2. The present invention effectively avoids the problem of ineffective dissolution of xanthan gum powder and easy particle agglomeration caused by directly adding xanthan gum powder by first uniformly dispersing it in a solvent to prepare a suspending agent and then adding the suspension to the solution for preparing the polishing slurry. This improves the dispersion stability and particle uniformity of the polishing slurry and reduces surface damage to polished PPS material components.

[0052] 3. This invention improves the dispersion and storage stability of the polishing slurry by synergistic effects of alumina homogenizer, suspending agent and HEC, thereby increasing the polishing rate of PPS material components and reducing surface damage and particle residue. Detailed Implementation

[0053] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0054] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0055] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the presence of other method steps before or after the combined steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0056] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention; in the specification and claims of the present invention, unless otherwise expressly stated in the text, the singular forms "a", "an" and "this" include the plural forms.

[0057] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0058] Example 1

[0059] This embodiment 1 provides a specific grinding fluid. Based on the total mass of the grinding fluid, the specific composition of the grinding fluid is: 50wt% alumina slurry, 1wt% suspending agent, 0.04wt% hydroxyethyl cellulose (HEC), 0.0015wt% LX-150, nitric acid is used to adjust the pH to 3.5, and the balance is water.

[0060] The specific preparation steps are as follows:

[0061] 1) Preparation of alumina slurry: Add 40 kg of water and 10 kg of alumina powder to a clean reactor. Disperse at 4000 r / min for 20 min. Adjust the stirring speed to 2000 r / min and stir for 20 min. Transfer to a 50 L transfer container and homogenize using a homogenizer at a pressure of 18000 Psi. Alumina slurry is obtained after homogenization.

[0062] 2) Preparation of suspension: Add 3 kg of propylene glycol to a clean 5 L beaker, start stirring at 50 r / min; slowly add 1 kg of xanthan gum, increase the stirring speed to 180 r / min, and stir for 30 min.

[0063] 3) Preparation of grinding fluid

[0064] a) Add alumina slurry to a clean reactor and turn on the stirring speed to 50 r / min;

[0065] b) Add water according to the ratio, adjust the speed to 100 r / min, and stir for 30 min;

[0066] c) Add the suspending agent according to the formula ratio, keep the speed constant, and stir for 30 minutes;

[0067] d) Add HEC according to the formula ratio, keep the speed constant, and stir for 30 minutes;

[0068] e) Adjust the pH to 3.50 with nitric acid, keeping the speed constant, and stir for 5 minutes to maintain the pH value.

[0069] f) Add LX-150 according to the ratio, keep the speed constant, and stir for 30 minutes; then filter to obtain the grinding liquid.

[0070] The particle size distribution of alumina slurry before and after homogenization was tested using a nanoparticle size potentiometer, and the results are shown in Table 1 below.

[0071] Table 1. Alumina particle size test results before and after homogenization

[0072]

[0073] As shown in Table 1, the particle sizes of alumina, D10, D50, D90 and D99, decreased to varying degrees before and after homogenization, with D99 ​​showing the most significant reduction. The particle size distribution of alumina was more concentrated after homogenization.

[0074] Examples 2-3

[0075] The difference between Examples 2 and 3 and Example 1 lies in the amount of alumina slurry added. In Example 2, the amount of alumina slurry added is 8 wt%, and in Example 3, the amount of alumina slurry added is 12 wt%. The remaining components and preparation methods are the same as in Example 1.

[0076] Comparative Examples 1-2

[0077] The difference between Comparative Examples 1 and 2 and Example 1 lies in the amount of alumina slurry added. In Comparative Example 1, the amount of alumina slurry added is 5 wt%, and in Comparative Example 2, the amount of alumina slurry added is 20 wt%. The remaining components and preparation methods are the same as in Example 1.

[0078] Examples 4-5

[0079] The difference between Examples 4 and 5 and Example 1 is the amount of suspending agent added. In Example 4, the amount of suspending agent added is 0.5 wt%, and in Example 5, the amount of suspending agent added is 1.5 wt%. The remaining components and preparation methods are the same as in Example 1.

[0080] Comparative Examples 3-4

[0081] The difference between Comparative Examples 3 and 4 and Example 1 is the amount of suspending agent added. No suspending agent was added in Comparative Example 3, and the amount of suspending agent added was 0. In Comparative Example 4, the amount of suspending agent added was 4 wt%. The other components and preparation methods were the same as in Example 1.

[0082] Examples 6-7

[0083] The difference between Examples 6 and 7 and Example 1 lies in the amount of hydroxyethyl cellulose added. In Example 6, the amount of hydroxyethyl cellulose added is 0.02 wt%, and in Example 7, the amount of hydroxyethyl cellulose added is 0.1 wt%. The remaining components and preparation methods are the same as in Example 1.

[0084] Comparative Examples 5-6

[0085] The difference between Comparative Examples 5 and 6 and Example 1 is the amount of HEC added. No HEC was added in Comparative Example 5, i.e., the amount of HEC added was 0, while the amount of HEC added in Comparative Example 6 was 0.5 wt%. The other components and preparation methods were the same as in Example 1.

[0086] Examples 8-10

[0087] The difference between Examples 8-10 and Example 1 lies in the pH value of the grinding slurry. The pH value of the grinding slurry in Example 8 is 2.0, the pH value of the grinding slurry in Example 9 is 3.0, and the pH value of the grinding slurry in Example 10 is 4.0. The remaining components and preparation methods are the same as those in Example 1.

[0088] Comparative Example 7

[0089] The difference between Comparative Example 7 and Example 1 is that the pH value of the grinding slurry is different. The pH value of the grinding slurry in Comparative Example 7 is 7.0. The other components and preparation methods are the same as those in Example 1.

[0090] Comparative Examples 8-9

[0091] The difference between Comparative Examples 8 and 9 and Example 1 is that the homogenization pressure during powder pretreatment is different. In Comparative Example 8, the alumina slurry is not homogenized, while in Comparative Example 9, the homogenization pressure is 10000 Psi. The other components and preparation methods are the same as in Example 1.

[0092] Comparative Example 10

[0093] The difference between Comparative Example 10 and Example 1 is that the suspension preparation step is omitted, and xanthan gum and propylene glycol are added directly in step c) according to the ratio and stirred for 30 minutes. The remaining components and preparation methods are the same as in Example 1.

[0094] In Comparative Example 10, after adding a suspending agent during the preparation of the grinding fluid, agglomeration occurred, resulting in an uneven grinding fluid with unacceptable dispersibility.

[0095] The formulations of the grinding fluids in Examples 1-10 and Comparative Examples 1-10 are shown in Table 2.

[0096] Table 2 Composition and Formulation of Grinding Fluid

[0097]

[0098] Test section

[0099] The performance of the polishing slurries prepared in the above embodiments and comparative examples of this application was tested. After the polishing slurries were prepared, they were left to stand for 1 day before the polishing performance was tested. The process conditions for polishing the PPS retaining ring are as follows:

[0100] Polishing equipment: Horizon

[0101] Polishing object: 12-inch PPS retaining ring

[0102] Polishing pad: H800

[0103] Polishing pressure: 1.0 psi

[0104] Polishing speed: 63 / 57 rpm

[0105] Grinding slurry flow rate: 250 mL / min

[0106] Polishing temperature: 42℃

[0107] Polishing time: 60s

[0108] 1) The polishing rate was measured using a KLA non-metallic film thickness gauge (F50). Specifically, the thickness of the 12-inch PPS retaining ring was measured before and after polishing. The polishing rate was calculated by dividing the difference in thickness before and after polishing by the polishing time. The results are shown in Table 3.

[0109] 2) Surface roughness Ra test: The test was performed using an atomic force microscope. The test area at each location was 10μm*10μm. The roughness of 3 locations was taken and the average value was calculated. The results are shown in Table 3.

[0110] 3) Surface particle residue and scratches: The polished PPS retaining ring was tested using a laser microscope to detect and count the number of particle residues and surface scratches. The number of scratches with a length >130nm was counted. The sample was measured three times, and the results are the average of the particle residue and the average of the number of scratches measured three times. The results are shown in Table 3.

[0111] 4) Metal and impurity content (excluding aluminum ions): The concentration of metal ions in the polishing slurry was detected using an Agilent 7900 ICP-MS system, and the concentrations of other metal ions besides aluminum ions were counted.

[0112] 5) Dispersion of the grinding slurry: After the prepared grinding slurry was placed at 25°C for 3 months, the sedimentation state of the particles in a transparent container was observed visually. If the grinding slurry remained a uniform turbid suspension, it was considered highly dispersed. If the grinding slurry was in a gel state and became a uniform turbid suspension after shaking, it was considered moderately dispersed. If it could not be shaken, it was considered poorly dispersed. The results are shown in Table 3. The highly dispersed grinding slurry was stored for another 12 months after 3 months, and its dispersibility was observed.

[0113] 6) Storage stability of polishing slurry: Samples of the polishing slurry prepared in Example 1 were stored for 1, 6 and 12 months to test the D50 particle size and specific gravity (the density of polishing slurry and the density of water at 20°C were measured using a portable densitometer, and the ratio of the density of polishing slurry to the density of water was calculated as the specific gravity of the corresponding polishing slurry). The results are shown in Table 4.

[0114] Table 3. Test results of grinding fluid performance

[0115]

[0116] Table 3 shows highly dispersed grinding slurries after 3 months of storage. The grinding slurries prepared in Examples 1-10 were retained and stored for up to 12 months. The grinding slurries remained in a uniform, turbid suspension state, without agglomeration or stratification. The grinding slurries prepared in this patent have good dispersion stability.

[0117] As shown in Table 3, the polishing slurries prepared in Examples 1-9 of this application all achieved polishing rates >80 nm / min, surface roughness Ra <3.5 nm, surface particle residue <20 particles, surface scratches <30, and total gold impurities (excluding aluminum ions) <150 ppb. The prepared polishing slurries remained uniformly dispersed, without sedimentation or agglomeration even after 12 months. From the examples and comparative examples, it can be seen that: the polishing rate of the polishing slurries prepared in Examples 1-3 increased with increasing alumina slurry content, while the surface particle residue and surface scratches slightly increased; combined with Comparative Example 2, it was found that as the alumina slurry content increased to 90%, the polishing rate tended to balance out and slightly decreased, while the surface residue and surface scratches increased, leading to a decrease in final polishing quality; in Comparative Example 1, reducing the alumina slurry content to 25 wt% resulted in a decrease in surface particle residue and surface scratches after polishing, but the polishing rate was <60 nm / min, which was relatively low. The amounts of suspending agent used in Examples 1, 4-5, and Comparative Examples 3-4 differed. The suspending agent was used to increase the suspension of the polishing slurry, allowing alumina particles to be better dispersed in the system. In Comparative Example 4, the amount of suspending agent was increased to 4 wt%. Excessive suspending agent resulted in an overly viscous polishing slurry, significantly reducing the polishing rate and increasing the amount of residual particles on the surface after polishing. In Comparative Example 3, without the addition of suspending agent, the polishing slurry easily settled and stratified, leading to a decrease in polishing rate and an increase in the number of surface scratches and surface roughness. The HEC content in Examples 1, 6-7, and Comparative Examples 5-6 differed. In Comparative Example 6, when the HEC content was increased to 0.5 wt%, the amount of residual particles on the surface was close to 0, and the number of surface scratches was 0, but the polishing rate decreased to 72 nm / min. In Comparative Example 5, without the addition of HEC, the polishing rate slightly increased, but the number of residual particles and surface scratches increased significantly, resulting in a significant decrease in polishing quality. The polishing slurries prepared in Examples 1, 8-10, and Comparative Example 7 have different pH values. In Comparative Example 7, when the pH of the polishing slurry increased to 7, the alumina polishing slurry became unstable in a neutral environment, and the polishing rate decreased to 56 nm / min. In Comparative Example 8, the alumina powder was not homogenized during slurry preparation. In Comparative Example 9, the pressure during alumina powder homogenization was insufficient, resulting in increased surface roughness, more surface scratches, and poorer dispersion stability after polishing. In Comparative Example 10, the xanthan gum and propylene glycol in the suspending agent were not mixed evenly beforehand and were directly added to prepare the polishing slurry, leading to an uneven and substandard polishing slurry. Forcibly using it for polishing resulted in a decreased polishing rate, a significant increase in surface particle residue and surface scratches, and substandard polishing quality.

[0118] Table 4. Stability of the grinding slurry prepared in Example 1 after 1, 6, and 12 months of storage.

[0119]

[0120] As shown in Table 4, the average particle size D of the grinding slurry prepared in Example 1 of this invention after 12 months of storage is... 50 The particle size increased only to 244 nm, an increase of <3%, and the specific gravity changed by less than 1%. The grinding slurry prepared in Example 1 has excellent storage stability.

[0121] Furthermore, to compare the effect of homogenization on the grinding fluid, the particle size and effect data of alumina before and after homogenization in Tables 1-3 are summarized in Table 5 below.

[0122] Table 5 Summary of test results on alumina particle size before and after homogenization and the preparation of grinding slurry

[0123]

[0124] As shown in Table 5, the alumina particles homogenized by the homogenizer are smaller and more concentrated. The prepared polishing slurry not only has high dispersibility and does not agglomerate or settle during long-term storage, but also reduces the surface roughness by 59%, the number of residual particles on the surface by 50%, and the number of surface scratches is close to 0 after polishing.

[0125] In summary, the alumina polishing slurry prepared in this invention achieves polishing rates >80 nm / min, surface roughness Ra <3.5 nm, surface particle residue of 0-20 particles, surface scratches of 0-30, and total gold impurities (excluding aluminum ions) content <150 ppb. The prepared polishing slurry exhibits good dispersion and storage stability, remaining uniformly dispersed without sedimentation or agglomeration even after 12 months of storage, with an average particle size increase of <3% and a specific gravity increase of <1%.

[0126] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An alumina polishing slurry for polishing PPS material components, characterized in that, The grinding slurry comprises the following raw material components by mass fraction: 40-60 wt% alumina slurry, 0.1-2 wt% suspending agent, 0.01-0.1 wt% hydroxyethyl cellulose, 0.001-0.002 wt% bactericide, and the balance being pH adjuster and water; the pH adjuster makes the pH value of the grinding slurry 2.0-4.0; the suspending agent includes xanthan gum and solvent; the mass ratio of alumina to water in the alumina slurry is 1:3.5-4.

5.

2. The alumina polishing slurry according to claim 1, characterized in that, The alumina particle size in the alumina slurry is 10~650nm.

3. The alumina polishing slurry according to claim 2, characterized in that, Alumina D in alumina slurry 50 Particle size is 200-250nm, D 90 The particle size is 430-460nm.

4. The alumina polishing slurry according to claim 1, characterized in that, The bactericide is LX-150; And / or, the pH adjuster is nitric acid; And / or, the mass ratio of xanthan gum to solvent in the suspending agent is 1:(2.5-3.5); And / or, the solvent in the suspending agent includes one or more of propylene glycol, glycerol, or butylene glycol; And / or, the xanthan gum, when prepared as a 0.1 wt% aqueous solution, has a viscosity of 500~1000 mPa·s at 25°C.

5. A method for preparing the grinding fluid as described in any one of claims 1 to 4, characterized in that, The preparation method includes: mixing alumina slurry, water, suspending agent, and hydroxyethyl cellulose evenly, adjusting the pH, adding bactericide and stirring evenly to obtain a grinding liquid.

6. The method for preparing the grinding fluid according to claim 5, characterized in that, The preparation method includes: 1) Add water and suspending agent to the alumina slurry, stir evenly to obtain the first mixture; 2) Add hydroxyethyl cellulose to the first mixture, stir evenly, add pH adjuster to adjust pH to 2-4, add bactericide, stir evenly, and obtain the grinding liquid.

7. The method for preparing the grinding fluid according to claim 5, characterized in that, The method for preparing the alumina slurry includes: mixing alumina and water, stirring evenly, and homogenizing using a homogenizer; And / or, the method for preparing the suspending agent includes: mixing the solvent and xanthan gum and stirring until homogeneous.

8. The preparation method according to claim 6, characterized in that, In step 1), the stirring speed of the alumina slurry after adding water is 45~55 r / min, and the stirring speed after adding the suspending agent is 90-120 r / min; And / or, in step 2), the stirring speed is 90-120 r / min.

9. The preparation method according to claim 7, characterized in that, The alumina slurry preparation process involves two stirring operations. The first stirring speed is 3800-4000 r / min and the first stirring time is 15-30 min. The second stirring speed is 1900-2000 r / min and the second stirring time is 15-30 min. And / or, the pressure of the homogenizer during homogenization is 16,000 to 20,000 psi; And / or, in the preparation of the suspension, the rotation speed of the solvent before mixing with xanthan gum is 45-55 r / min, and the rotation speed after mixing with xanthan gum is 175-185 r / min.

10. The application of an abrasive slurry as described in any one of claims 1 to 4 in the polishing of PPS material components, characterized in that, The applications include reducing the surface roughness of PPS material components; and / or increasing the polishing rate.

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