Rough polishing liquid applied to diamond substrate and preparation method of rough polishing liquid

Abstract

The preparation method comprises the following steps: selecting an abrasive material base material, mixing the abrasive material base material with a silane coupling agent for chemical modification, coating the surface with a modified abrasive material with a functional layer, adding the modified abrasive material into a stirring container, and dispersing to obtain the rough polishing liquid applied to the diamond substrate. An oxidizing agent and a dispersing agent are added into the abrasive dispersion liquid to be stirred to form a polishing solution, the particle size distribution condition of the modified abrasive in the polishing solution is monitored in real time through an online particle size analyzer, and the ultrasonic power and the treatment time are automatically adjusted; adding a pH regulator into the polishing solution by adopting a step-by-step titration method, and adjusting the pH value to 6-9; the polishing solution is filtered through a micro-filtration membrane, undispersed particles and impurities are removed, and a polishing solution finished product is obtained; through the chemical modification and ultrasonic-assisted technology and the real-time monitoring and automatic adjusting process, the dispersity of the grinding material and the uniformity of the polishing solution are remarkably improved, and the particle size distribution of the grinding material is optimized, so that the high-quality polishing solution is obtained.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a rough polishing liquid applied to a diamond substrate and a preparation method thereof. Background Art

[0002] In the semiconductor and optoelectronics industries, diamond is widely used as a substrate material due to its excellent thermal conductivity, hardness and chemical stability. However, due to the extremely high hardness and brittleness of diamond, its processing, especially the polishing process, has always been a technical challenge in the industry. High-quality diamond substrates are crucial to improving device performance and reliability. Therefore, the research and development of efficient diamond polishing technology has important industrial value.

[0003] In the prior art, polishing of diamond substrates usually relies on a combination of mechanical polishing and chemical mechanical polishing (CMP); however, these methods still have significant deficiencies in improving polishing efficiency and surface quality. A core technical problem is the poor dispersion of abrasives in the polishing liquid, which leads to uneven polishing, which in turn affects the surface smoothness and processing accuracy of the substrate. This unevenness often leads to abrasive aggregation, forming scratches or surface defects, which limits the use of diamond substrates in high-precision applications.

[0004] In view of this, there is a need to improve the polishing material of the diamond substrate in the prior art to solve the technical problems of poor dispersion and uniformity of the polishing material. Summary of the invention

[0005] The purpose of the present invention is to provide a rough polishing liquid for diamond substrate and a preparation method thereof, so as to solve the above technical problems.

[0006] To achieve this object, the present invention adopts the following technical solutions: A method for preparing a rough polishing liquid for use on a diamond substrate, comprising: Selecting nano-aluminum oxide or silicon carbide as an abrasive substrate, mixing the abrasive substrate with a silane coupling agent, and chemically modifying the abrasive substrate in an ultrasonic reactor with the assistance of ultrasonic waves to form a modified abrasive having a functional layer coated on the surface of the abrasive substrate; The modified abrasive obtained is added into a stirring container, deionized water is added for preliminary dispersion to form an abrasive dispersion, then an oxidant and a dispersant are added into the abrasive dispersion according to a preset ratio, and ultrasonic stirring is used to form a polishing liquid; During the ultrasonic stirring process, the particle size distribution of the modified abrasive in the polishing liquid is monitored in real time by an online particle size analyzer, and the ultrasonic power and processing time are automatically adjusted according to the particle size distribution monitored in real time; A pH regulator is added to the polishing liquid by a stepwise titration method to adjust the pH value to a range of 6-9; The polishing liquid is filtered through a microfiltration membrane to remove undispersed particles and impurities to obtain a finished polishing liquid.

[0007] Optionally, the abrasive substrate is selected as nano-aluminum oxide or silicon carbide, the abrasive substrate is mixed with a silane coupling agent, and chemically modified in an ultrasonic reactor with the assistance of ultrasound to form a modified abrasive having a functional layer coated on the surface of the abrasive substrate, specifically comprising: Selecting nano-aluminum oxide or silicon carbide as an abrasive substrate, and performing plasma activation pretreatment on the surface of the abrasive substrate; The pretreated abrasive substrate is mixed with a preset silane coupling agent according to a first preset mass ratio, so that the silane coupling agent is evenly covered on the surface of the abrasive substrate; The mixture of the abrasive substrate and the silane coupling agent is placed in an ultrasonic reactor, and a chemical modification reaction is carried out under the assistance of ultrasonic waves to obtain a modified abrasive; wherein the chemical modification reaction conditions are a reaction temperature in the range of 25-60° C. and a reaction time in the range of 2-4 hours.

[0008] Optionally, the mixture of the abrasive substrate and the silane coupling agent is placed in an ultrasonic reactor, and subjected to a chemical modification reaction under the assistance of ultrasonic waves to obtain a modified abrasive, and then the method further comprises: After the chemical modification reaction is completed, the modified abrasive is separated from the unreacted silane coupling agent by centrifugal separation; The modified abrasive was washed several times with deionized water to remove unreacted silane coupling agent; The washed modified abrasive is dried in a vacuum drying oven at 80-120° C. for 12-24 hours to form a modified abrasive having a functional layer.

[0009] Optionally, the modified abrasive obtained is added into a stirring container, deionized water is added for preliminary dispersion to form an abrasive dispersion, an oxidant and a dispersant are then added into the abrasive dispersion in a preset ratio, and ultrasonic stirring is used to form a polishing liquid, specifically comprising: The obtained modified abrasive is measured according to the second preset mass ratio, and slowly added into a stirring container, and deionized water pre-cooled to 4-10° C. is slowly added into the stirring container, while the temperature is maintained in the range of 15-25° C., and preliminary dispersion is performed to form an abrasive dispersion liquid; Adding an oxidant and a dispersant according to a preset molar ratio; wherein the oxidant is hydrogen peroxide and the dispersant is a bio-based polymer; A dual-frequency ultrasonic device is used to perform ultrasonic-assisted stirring on the abrasive dispersion to form a polishing solution; the reaction conditions are set to alternately act at a low frequency of 20-40 kHz and a high frequency of 100-200 kHz, and the ultrasonic treatment time is 30-60 minutes.

[0010] Optionally, during the ultrasonic stirring process, the particle size distribution of the modified abrasive in the polishing liquid is monitored in real time by an online particle size analyzer, and the ultrasonic power and processing time are automatically adjusted according to the particle size distribution monitored in real time, specifically including: During the ultrasonic stirring process, a laser scattering particle size analyzer is used to monitor the particle size distribution of the polishing liquid in real time; Setting preset particle size distribution standard parameters, wherein the particle size distribution standard parameters include particle size range, average particle size and particle size distribution width; The particle size distribution data monitored by the laser scattering particle size analyzer is transmitted to the central control unit through the control system, and the central control unit analyzes the deviation between the particle size distribution data and the particle size distribution standard parameters based on the built-in feedback control algorithm; When the real-time monitored particle size distribution data deviates from the particle size distribution standard parameter, the control system sets an adjustment strategy for the power output of the dual-frequency ultrasonic device according to the deviation value; The ultrasonic power and processing time are automatically adjusted according to the power output adjustment strategy.

[0011] Optionally, the control system sets an adjustment strategy for the power output of the dual-frequency ultrasonic device according to the deviation value, specifically including: Define the particle size distribution deviation ΔD monitored in real time, where ΔD = D_actual - D_target; D_actual is the average particle size obtained by real-time monitoring, and D_target is the preset particle size distribution standard parameter; According to the size and direction of the particle size deviation ΔD, formulate an adjustment strategy for the ultrasonic power output; The functional relationship between the ultrasonic power adjustment ΔP and the particle size deviation ΔD was established, and the linear model ΔP = K_p× ΔD was adopted; where ΔP is the ultrasonic power adjustment and K_p is the power adjustment coefficient; Calculate the power adjustment amounts ΔP_low and ΔP_high of the low-frequency and high-frequency ultrasonic waves respectively, and set the adjustment proportional coefficient β, ΔP_low = β × ΔP, ΔP_high = (1 - β) × ΔP.

[0012] Optionally, the stepwise titration method is used to add a pH regulator to the polishing liquid to adjust the pH value to a range of 6-9, specifically comprising: An online pH monitoring instrument is installed in the stirring container to monitor the pH value of the polishing liquid in real time; Select a weakly acidic or weakly alkaline pH regulator, wherein the pH regulator is an inorganic acid or an inorganic base; titrating by a stepwise titration method using an automatic titration device, wherein the stepwise titration method includes setting an initial dropping speed of the pH adjuster to a higher value, and then adding the pH adjuster dropwise to the polishing liquid at a preset constant micro flow rate; During the titration process, the pH value change trend of the polishing liquid is obtained in real time through the online pH monitoring instrument, and the dripping speed and dripping amount of the pH regulator are dynamically adjusted according to the degree to which the pH value is close to the target range; the dynamic adjustment process specifically includes: When the pH value is significantly different from the target range, maintain a higher drop rate; When the pH value gradually approaches the lower or upper limit of the target range, gradually reduce the dripping speed.

[0013] The present invention also provides a rough polishing liquid for diamond substrates, which is prepared by the above-mentioned method for preparing a rough polishing liquid for diamond substrates, and the rough polishing liquid comprises: A modified abrasive, wherein the modified abrasive is made of nano-aluminum oxide or silicon carbide as an abrasive substrate, the abrasive substrate is mixed with a silane coupling agent, and a functional layer is formed on the surface of the modified abrasive through chemical modification; Deionized water, used to preliminarily disperse the modified abrasive to form an abrasive dispersion; an oxidizing agent, added to the abrasive dispersion in a predetermined proportion; A dispersant is added to the abrasive dispersion according to a preset ratio; The pH adjuster is added by gradual titration to adjust the pH value of the polishing liquid to a range of 6-9.

[0014] Compared with the prior art, the present invention has the following beneficial effects: by using a silane coupling agent in an ultrasonic reactor to chemically modify the abrasive, a functional layer is formed on its surface to improve the dispersibility and stability of the abrasive; in the preparation process, the modified abrasive is uniformly dispersed in the polishing liquid by ultrasonic stirring, and the particle size distribution is monitored in real time by an online particle size analyzer, and the ultrasonic parameters are automatically adjusted to optimize the dispersion effect; then the stepwise titration method is used to accurately adjust the pH value of the polishing liquid, and the undispersed particles and impurities are removed by microfiltration membrane filtration to ensure the purity and performance of the polishing liquid; this scheme significantly improves the dispersibility of the abrasive and the uniformity of the polishing liquid through chemical modification and ultrasonic auxiliary technology, and the process of real-time monitoring and automatic adjustment, optimizes the particle size distribution of the abrasive, so as to obtain high-quality polishing liquid, and improve the smoothness and processing quality of the surface processing of the diamond substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0017] Figure 1 This is one of the schematic diagrams of the preparation process of the preparation method of Example 1; Figure 2 The second schematic diagram of the preparation process of the preparation method of the first embodiment; Figure 3 This is the third schematic diagram of the preparation process of the preparation method of Example 1. DETAILED DESCRIPTION

[0018] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0020] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0021] Embodiment 1: Combination Figures 1 to 3 As shown, an embodiment of the present invention provides a method for preparing a rough polishing liquid applied to a diamond substrate, comprising: S1, selecting nano-aluminum oxide or silicon carbide as an abrasive substrate, mixing the abrasive substrate with a silane coupling agent, and chemically modifying the abrasive substrate in an ultrasonic reactor with the assistance of ultrasound to form a modified abrasive having a functional layer coated on the surface of the abrasive substrate; Nano-alumina or silicon carbide is selected as the abrasive substrate. Nano-abrasives can provide higher polishing accuracy and efficiency due to their small particle size and large specific surface area. The abrasive substrate is mixed with a silane coupling agent in order to form a functional layer on the abrasive surface through chemical modification. The silane coupling agent has a bifunctional group, one end of which can react with the hydroxyl group or other active groups on the abrasive surface, and the other end can provide hydrophilicity or other functions. This chemical modification process is carried out in an ultrasonic reactor, using the mechanical vibration and cavitation effect of ultrasound to promote full contact and reaction between the coupling agent and the abrasive surface. Finally, a functional layer of modified abrasive is formed on the surface of the abrasive substrate, which improves the dispersibility and stability of the abrasive and is beneficial to the subsequent polishing process.

[0022] S2, adding the obtained modified abrasive into a stirring container, adding deionized water for preliminary dispersion to form an abrasive dispersion, then adding an oxidant and a dispersant into the abrasive dispersion according to a preset ratio, and stirring with ultrasound to form a polishing liquid; The modified abrasive is added to a stirring container, and deionized water is added for preliminary dispersion to form an abrasive dispersion. The use of deionized water can avoid the influence of impurity ions on the performance of the polishing liquid and ensure the purity of the system. Subsequently, an oxidant and a dispersant are added to the abrasive dispersion according to a preset ratio. The role of the oxidant is to enhance the chemical mechanical polishing ability of the polishing liquid, moderately oxidize the surface of the diamond substrate, and help improve the polishing efficiency. The addition of the dispersant further improves the dispersion stability of the abrasive in the polishing liquid and prevents the aggregation and sedimentation of the abrasive particles. Ultrasonic stirring is used to promote the uniform dispersion of the abrasive using the energy of the ultrasonic wave to form a polishing liquid with stable performance.

[0023] S3, during the ultrasonic stirring process, the particle size distribution of the modified abrasive in the polishing liquid is monitored in real time by an online particle size analyzer, and the ultrasonic power and processing time are automatically adjusted according to the particle size distribution monitored in real time; During the ultrasonic stirring process, the particle size distribution of the modified abrasive in the polishing liquid is monitored in real time by an online particle size analyzer. Particle size distribution is one of the key factors affecting the polishing effect. Too large particles may cause scratches, and too small particles may reduce the polishing efficiency. Through real-time monitoring, the changes in the abrasive particle size can be obtained in time. According to the monitored particle size distribution data, the system automatically adjusts the power and processing time of the ultrasonic wave. For example, when it is found that the particle size is too large, the ultrasonic power can be increased or the processing time can be extended to promote further dispersion of the abrasive; when the particle size is too small, the power can be reduced or the time can be shortened to prevent excessive crushing of the abrasive. Such an automatic adjustment mechanism ensures that the particle size distribution of the polishing liquid is always in the best state, improving the quality of the polishing liquid and the polishing effect.

[0024] S4, adding a pH regulator to the polishing liquid by a stepwise titration method to adjust the pH value to a range of 6-9; The pH regulator is added to the polishing liquid by stepwise titration to adjust the pH value to a range of 6-9. The pH value has an important influence on the stability of the polishing liquid and the polishing effect. An overly acidic or alkaline environment may cause the abrasive to aggregate or the dispersant to fail. The stepwise titration method is an accurate pH adjustment method. By adding the pH regulator slowly and in batches, the pH value changes are monitored in real time to avoid excessive changes in the pH value caused by adding too much at one time. This can better control the pH value of the polishing liquid and ensure its stability and effectiveness.

[0025] S5, filtering the polishing liquid through a microfiltration membrane to remove undispersed particles and impurities to obtain a finished polishing liquid.

[0026] The polishing liquid is filtered through a microfiltration membrane to remove undispersed particles and impurities to obtain a finished polishing liquid. The filtration pore size of the microfiltration membrane is usually in the range of 0.1-1 micron, which can effectively intercept large particles and insoluble impurities to ensure the purity and uniformity of the polishing liquid. This step is very critical to improving the quality of the polishing liquid. The filtered polishing liquid has better stability and polishing effect, and is suitable for precision polishing of diamond substrates.

[0027] The working principle of the present invention is as follows: a silane coupling agent is used in an ultrasonic reactor to chemically modify an abrasive so that a functional layer is formed on its surface to improve the dispersibility and stability of the abrasive; in the preparation process, ultrasonic stirring is used to uniformly disperse the modified abrasive in a polishing liquid, and the particle size distribution is monitored in real time by an online particle size analyzer, and ultrasonic parameters are automatically adjusted to optimize the dispersion effect; then a stepwise titration method is used to accurately adjust the pH value of the polishing liquid, and undispersed particles and impurities are removed by microfiltration membrane filtration to ensure the purity and performance of the polishing liquid; the scheme significantly improves the dispersibility of the abrasive and the uniformity of the polishing liquid through chemical modification and ultrasonic auxiliary technology, and the process of real-time monitoring and automatic adjustment, optimizes the particle size distribution of the abrasive, so as to obtain a high-quality polishing liquid, and improve the smoothness and processing quality of the surface processing of the diamond substrate.

[0028] In this embodiment, it is specifically explained that step S1 specifically includes: S11, selecting nano-aluminum oxide or silicon carbide as an abrasive substrate, and performing plasma activation pretreatment on the surface of the abrasive substrate; Nano-abrasives have ultra-fine particle sizes and high specific surface areas, which can provide higher polishing accuracy and efficiency. In order to enhance the reactivity of the surface of the abrasive substrate, it is pre-treated with plasma activation. Plasma activation treatment is to introduce active groups (such as hydroxyl, carboxyl, etc.) on the surface of the abrasive substrate through the action of high-energy plasma in a specific atmosphere to increase its surface energy and chemical activity. This step helps to improve the subsequent bonding efficiency with silane coupling agents.

[0029] S12, mixing the pretreated abrasive substrate with a preset silane coupling agent according to a first preset mass ratio, so that the silane coupling agent is evenly covered on the surface of the abrasive substrate; The pretreated abrasive substrate is mixed with a preset silane coupling agent according to a first preset mass ratio. Silane coupling agent is a type of compound with a bifunctional group, one end of which can react with an active group (such as Si-OH) on the surface of an inorganic material, and the other end contains an organic functional group. By precisely controlling the mass ratio, it is ensured that the silane coupling agent can be evenly covered on the surface of the abrasive substrate, so that each abrasive particle has a uniform functional layer.

[0030] S13, placing the mixture of the abrasive substrate and the silane coupling agent in an ultrasonic reactor, and performing a chemical modification reaction under the assistance of ultrasonic waves to obtain a modified abrasive; wherein the chemical modification reaction conditions are a reaction temperature in the range of 25-60° C. and a reaction time in the range of 2-4 hours.

[0031] The mixture is placed in an ultrasonic reactor and subjected to a chemical modification reaction under the assistance of ultrasound. The ultrasonic reactor utilizes the mechanical vibration and cavitation effect of ultrasound to promote the full mixing and reaction of the abrasive substrate and the silane coupling agent. The reaction conditions are set at a temperature of 25-60°C and a time of 2-4 hours. These conditions help accelerate the chemical reaction while preventing excessive temperatures from causing a decrease in material properties. Ultimately, a stable functional layer is formed on the surface of the abrasive substrate, giving the abrasive new physical and chemical properties.

[0032] S14, after the chemical modification reaction is completed, separating the modified abrasive from the unreacted silane coupling agent by centrifugal separation; After the chemical modification reaction is completed, the modified abrasive is separated from the unreacted silane coupling agent by centrifugal separation. Centrifugal separation uses the centrifugal force generated by high-speed rotation to separate components with different densities. This can effectively remove the unreacted silane coupling agent and other impurities to ensure the purity of the modified abrasive.

[0033] S15, washing the modified abrasive with deionized water for multiple times to remove unreacted silane coupling agent; The modified abrasive is washed multiple times with deionized water to remove the residual unreacted silane coupling agent and possible solvents or by-products. Multiple washings can ensure the cleanliness of the modified abrasive surface and avoid the influence of residues on the performance of subsequent polishing liquid. The use of deionized water can prevent the introduction of additional ionic impurities.

[0034] S16, drying the washed modified abrasive in a vacuum drying oven at 80-120° C. for 12-24 hours to form a modified abrasive having a functional layer.

[0035] The washed modified abrasive is dried in a vacuum drying oven at 80-120°C for 12-24 hours. Vacuum drying can reduce the boiling point, accelerate the evaporation of water, and prevent high-temperature oxidation or thermal decomposition. The dried modified abrasive has a stable functional layer, good dispersibility and polishing performance, laying the foundation for the preparation of high-quality polishing liquid.

[0036] In this embodiment, it is specifically described that step S2 specifically includes: S21, measuring the obtained modified abrasive according to the second preset mass ratio, and slowly adding it into a stirring container, slowly adding deionized water pre-cooled to 4-10° C. into the stirring container, while maintaining the temperature in the range of 15-25° C., and performing preliminary dispersion to form an abrasive dispersion; The modified abrasive obtained is measured according to the second preset mass ratio and slowly added to a container with a stirring function. To ensure uniform dispersion of the abrasive, the abrasive should be added gradually, and the agitator should be turned on at the same time so that the abrasive is continuously stirred and dispersed during the addition process. Slowly add deionized water that has been pre-cooled to 4-10°C. The cooled deionized water helps control the temperature of the system to prevent abrasive agglomeration or performance degradation due to increased temperature. Maintain the temperature in the stirring container within the range of 15-25°C. This temperature range is conducive to the stable dispersion of the abrasive and avoids the influence of high temperature on the activity of the oxidant and dispersant. Through the above operations, the abrasive dispersion is initially dispersed to form a foundation for subsequent steps.

[0037] S22, adding an oxidant and a dispersant according to a preset molar ratio; wherein the oxidant is hydrogen peroxide and the dispersant is a bio-based polymer; Add oxidant and dispersant to the abrasive dispersion according to a preset molar ratio. Hydrogen peroxide (H2O2) is used as the oxidant. As a highly efficient oxidant, it can moderately oxidize the surface of the diamond substrate during the polishing process and improve the polishing efficiency. Bio-based polymer is used as the dispersant. This dispersant is environmentally friendly and biodegradable. It also has good dispersing properties and can effectively prevent the aggregation and sedimentation of abrasive particles. Adding in a precise molar ratio ensures that the concentrations of the oxidant and dispersant meet the process requirements, which helps to stabilize and optimize the performance of the polishing liquid.

[0038] S23, using a dual-frequency ultrasonic device to perform ultrasonic-assisted stirring on the abrasive dispersion to form a polishing liquid; the reaction conditions are set to alternately act at a low frequency of 20-40 kHz and a high frequency of 100-200 kHz, and the ultrasonic treatment time is 30-60 minutes.

[0039] A dual-frequency ultrasonic device is used to perform ultrasonic-assisted stirring on the abrasive dispersion to form a polishing liquid. The dual-frequency ultrasonic device is set to alternately act at a low frequency of 20-40 kHz and a high frequency of 100-200 kHz, and utilizes the physical effects of ultrasonic waves of different frequencies to promote uniform dispersion of the abrasive.

[0040] Low-frequency ultrasound has a strong cavitation effect and mechanical vibration, which can effectively destroy the aggregates between particles and fully disperse the abrasive particles. High-frequency ultrasound has a higher energy density, which can further refine the particles and improve the uniformity and stability of dispersion. The use of low-frequency and high-frequency ultrasound alternately can give full play to their respective advantages and achieve the best dispersion effect. The ultrasonic treatment time is set to 30-60 minutes. This time range can ensure that the abrasive is fully dispersed while avoiding excessive particle crushing or excessive energy consumption due to too long treatment time.

[0041] During the ultrasonic-assisted stirring process, the temperature and pressure of the polishing liquid should also be properly controlled to prevent overheating or overpressure from adversely affecting the system.

[0042] In this embodiment, it is specifically described that step S3 specifically includes: S31, during the ultrasonic stirring process, a laser scattering particle size analyzer is used to monitor the particle size distribution of the polishing liquid in real time; During the ultrasonic stirring process, a laser scattering particle size analyzer is used to monitor the particle size distribution of the polishing liquid in real time. The laser scattering particle size analyzer irradiates the sample with a laser beam and analyzes the scattering intensity and angle distribution of the particles to the laser, thereby accurately determining the particle size distribution. The advantage of real-time monitoring is that it can timely obtain the dynamic changes of abrasive particles in the polishing liquid, ensuring that the polishing liquid maintains a stable particle size distribution throughout the preparation process. This is crucial to prevent excessive aggregation or excessive fragmentation of abrasive particles and ensure the polishing effect.

[0043] S32, setting preset standard parameters for particle size distribution, wherein the standard parameters for particle size distribution include particle size range, average particle size and particle size distribution width; and serving as a reference for automatically adjusting ultrasonic power and processing time.

[0044] According to the specific polishing requirements, preset particle size distribution standard parameters are set. The particle size distribution standard parameters include particle size range, average particle size and particle size distribution width. The particle size range determines the minimum and maximum sizes of the abrasive particles, the average particle size reflects the overall distribution trend of the abrasive particles, and the particle size distribution width describes the uniformity of the particle size. Reasonable setting of these parameters can ensure that the polishing liquid has the best polishing performance and stability. For example, a smaller average particle size and a narrower distribution width can help improve polishing accuracy and reduce surface scratches.

[0045] S33, transmitting the particle size distribution data monitored by the laser scattering particle size analyzer to the central control unit through the control system, and the central control unit analyzes the deviation between the particle size distribution data and the particle size distribution standard parameters based on the built-in feedback control algorithm; The particle size distribution data monitored by the laser scattering particle size analyzer is transmitted to the central control unit through the control system. The feedback control algorithm built into the central control unit will analyze the deviation between the actual particle size distribution data and the preset particle size distribution standard parameters in real time. The feedback control algorithm evaluates whether the particle size distribution of the current polishing liquid meets the process requirements based on the size and direction of the deviation. If the particle size distribution is found to deviate from the preset standard, the system will generate corresponding adjustment instructions to correct the current ultrasonic processing parameters.

[0046] S34, when the real-time monitored particle size distribution data deviates from the particle size distribution standard parameters, the control system sets the adjustment strategy of the power output of the dual-frequency ultrasonic device according to the deviation value; for example, when the particle size is too large, the low-frequency and high-frequency ultrasonic powers are reduced to reduce particle breakage, while extending the processing time to promote particle redispersion.

[0047] S35, according to the power output adjustment strategy, automatically adjust the ultrasonic power and processing time. The adjusted ultrasonic device continues to process the polishing liquid, while the central control unit continues to monitor the particle size distribution data in real time, forming a closed-loop control system. Through continuous feedback and adjustment, it is ensured that the particle size distribution of the polishing liquid is always kept within the preset optimization range.

[0048] In this embodiment, it is further explained that step S34 specifically includes: S341, defining the particle size distribution deviation ΔD monitored in real time, where ΔD = D_actual - D_target; D_actual is the average particle size obtained by real-time monitoring, and D_target is a preset particle size distribution standard parameter.

[0049] S342, formulating an adjustment strategy for ultrasonic power output according to the size and direction of the particle size deviation ΔD; specifically including: When ΔD>0, increasing the ultrasonic power or extending the treatment time indicates particle agglomeration to promote further dispersion of particles; When ΔD<0 (the actual average particle size is smaller than the standard parameter of particle size distribution), reducing the ultrasonic power or shortening the processing time indicates that the particles may be over-broken to prevent the particles from being too fine and affecting the polishing effect.

[0050] S343, establishing a functional relationship between the ultrasonic power adjustment amount ΔP and the particle size deviation ΔD, using a linear model ΔP = K_p × ΔD; wherein ΔP is the ultrasonic power adjustment amount, K_p is the power adjustment coefficient, K_p is determined based on experience or experimental data, and the unit is W / μm.

[0051] S344, respectively calculate the power adjustment amounts ΔP_low and ΔP_high of the low-frequency and high-frequency ultrasonic waves, and set the adjustment proportional coefficient β (0≤β≤1), ΔP_low = β × ΔP, ΔP_high = (1 - β) × ΔP. As needed, the β value can be selected to control the adjustment amplitude of the low-frequency and high-frequency powers, and is used to allocate the power adjustment amount between the low frequency and the high frequency.

[0052] In this embodiment, it is specifically described that step S4 specifically includes: S41, installing an online pH monitoring instrument in the stirring container to monitor the pH value of the polishing liquid in real time; Install an online pH monitoring instrument in the mixing vessel to monitor the pH value of the polishing liquid in real time. The online pH monitoring instrument can continuously and accurately measure the pH value of the polishing liquid, avoiding the delays and errors caused by sampling measurements. Real-time monitoring is essential for precise control of pH value, because small changes in pH value can have a significant impact on the performance of the polishing liquid. By connecting the pH monitoring instrument directly to the mixing vessel, the timeliness and accuracy of the data are ensured, providing a reliable basis for subsequent pH adjustments.

[0053] S42, selecting a weakly acidic or weakly alkaline pH regulator, wherein the pH regulator is an inorganic acid or an inorganic base; A weakly acidic or weakly alkaline pH regulator is selected, and the pH regulator is an inorganic acid or an inorganic base. Commonly used inorganic acids include dilute hydrochloric acid, dilute nitric acid, etc., and commonly used inorganic bases include dilute sodium hydroxide solution, ammonia water, etc. The purpose of selecting a weak acid or a weak base as a pH regulator is to avoid adverse effects on the chemical properties of other components in the polishing liquid (such as abrasives, oxidants, dispersants) during the process of adjusting the pH value. Inorganic acids and inorganic bases have the characteristics of rapid reaction and easy control, and are suitable for precise pH adjustment.

[0054] S43, titration is performed by a stepwise titration method using an automatic titration device, wherein the stepwise titration method includes setting the initial dripping speed of the pH adjuster to a higher value, and then adding it dropwise to the polishing liquid at a preset constant small flow rate; so as to quickly approach the target pH range, while maintaining continuous stirring of the polishing liquid to ensure that the pH adjuster is fully mixed with the polishing liquid.

[0055] The pH value of the polishing liquid is adjusted by the step-by-step titration method through an automatic titration device. The step-by-step titration method is characterized by quickly approaching the target pH range with a high drop rate in the initial stage, and then adding the pH regulator drop by drop at a preset constant micro flow rate to finely adjust the pH value to the target range. The specific process includes: Initial titration stage: Set the pH adjuster drop rate to a higher value, such as adding a certain volume of adjuster per minute, to quickly change the pH value of the polishing liquid to bring it close to the target range. This stage is designed to save time and improve adjustment efficiency.

[0056] Fine titration stage: When the pH value is close to the target range, reduce the dripping speed and switch to adding the regulator drop by drop at a constant and small flow rate. This can avoid over-adjustment that causes the pH value to exceed the target range. Precise control of the small flow rate helps to achieve fine adjustment of the pH value.

[0057] The automatic titration device can accurately control the dripping speed and dripping amount of the regulator, and is linked with the online pH monitoring instrument to achieve closed-loop control, ensuring the accuracy and reliability of pH adjustment.

[0058] S44, during the titration process, the pH value change trend of the polishing liquid is obtained in real time through an online pH monitoring instrument, and the dripping speed and dripping amount of the pH regulator are dynamically adjusted according to the degree to which the pH value is close to the target range; the dynamic adjustment process specifically includes: When the pH value is significantly different from the target range, maintain a higher drop rate; When the pH value gradually approaches the lower or upper limit of the target range, gradually reduce the dripping speed. Use a fine titration method to avoid over-adjustment that causes the pH value to exceed the target range.

[0059] The key to dynamic adjustment is to flexibly adjust the titration parameters according to the real-time pH value change trend. To achieve this, a real-time data feedback mechanism can be established between the automatic titration device and the pH monitor, and the control system automatically adjusts the dripping speed and dripping amount according to the preset algorithm. For example, when the pH value change rate (ΔpH / Δt) is too large, the dripping speed is automatically reduced; when the change rate is too small and the pH value has not yet reached the target range, the dripping speed can be appropriately increased.

[0060] The innovation lies in: 1. Through the combination of online pH monitoring and automatic titration device, the automation and real-time control of pH adjustment process are realized, which reduces manual intervention and improves the accuracy and efficiency of adjustment.

[0061] 2. According to the difference between the pH value and the target range, the pH regulator’s dripping speed and dripping amount are dynamically adjusted to avoid over-adjustment or under-adjustment. This intelligent adjustment strategy improves the accuracy of pH control and ensures the chemical stability of the polishing liquid.

[0062] 3. The step-by-step titration method is used to combine the initial rapid adjustment with the later fine adjustment, which ensures both the adjustment speed and the adjustment accuracy. This method is innovative in the preparation of polishing liquid and can meet the requirements for precise control of pH value.

[0063] Embodiment 2: The present invention further provides a rough polishing liquid for diamond substrates, which is prepared by the preparation method of the rough polishing liquid for diamond substrates as described in Example 1, and the rough polishing liquid comprises: The modified abrasive is made of nano-aluminum oxide or silicon carbide as an abrasive substrate, the abrasive substrate is mixed with a silane coupling agent, and a functional layer is formed on the surface of the modified abrasive through chemical modification.

[0064] Deionized water is used to preliminarily disperse the modified abrasive to form an abrasive dispersion.

[0065] The oxidant is added to the abrasive dispersion in a preset ratio to enhance the oxidizing property of the polishing solution.

[0066] The dispersant is added into the abrasive dispersion according to a preset ratio to promote uniform dispersion of the modified abrasive in the polishing liquid.

[0067] The pH adjuster is added by gradual titration to adjust the pH value of the polishing liquid to within the range of 6-9 to stabilize the chemical properties of the polishing liquid.

[0068] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a rough polishing liquid for diamond substrates, characterized in that: include: Selecting nano-aluminum oxide or silicon carbide as an abrasive substrate, mixing the abrasive substrate with a silane coupling agent, and chemically modifying the abrasive substrate in an ultrasonic reactor with the assistance of ultrasonic waves to form a modified abrasive having a functional layer coated on the surface of the abrasive substrate; The modified abrasive obtained is added into a stirring container, deionized water is added for preliminary dispersion to form an abrasive dispersion, then an oxidant and a dispersant are added into the abrasive dispersion according to a preset ratio, and ultrasonic stirring is used to form a polishing liquid; During the ultrasonic stirring process, the particle size distribution of the modified abrasive in the polishing liquid is monitored in real time by an online particle size analyzer, and the ultrasonic power and processing time are automatically adjusted according to the particle size distribution monitored in real time; A pH regulator is added to the polishing liquid by a stepwise titration method to adjust the pH value to a range of 6-9; The polishing liquid is filtered through a microfiltration membrane to remove undispersed particles and impurities to obtain a finished polishing liquid.

2. The method for preparing a rough polishing liquid for diamond substrate according to claim 1, characterized in that: The method of selecting nano-aluminum oxide or silicon carbide as an abrasive substrate, mixing the abrasive substrate with a silane coupling agent, and chemically modifying the abrasive substrate in an ultrasonic reactor with the assistance of ultrasound to form a modified abrasive having a functional layer coated on the surface of the abrasive substrate specifically includes: Selecting nano-aluminum oxide or silicon carbide as an abrasive substrate, and performing plasma activation pretreatment on the surface of the abrasive substrate; The pretreated abrasive substrate is mixed with a preset silane coupling agent according to a first preset mass ratio, so that the silane coupling agent is evenly covered on the surface of the abrasive substrate; The mixture of the abrasive substrate and the silane coupling agent is placed in an ultrasonic reactor, and a chemical modification reaction is carried out under the assistance of ultrasonic waves to obtain a modified abrasive; wherein the chemical modification reaction conditions are a reaction temperature in the range of 25-60° C. and a reaction time of 2-4 hours.

3. The method for preparing a rough polishing liquid for diamond substrate according to claim 2, characterized in that: The method further comprises placing a mixture of the abrasive substrate and the silane coupling agent in an ultrasonic reactor, and performing a chemical modification reaction under the assistance of ultrasonic waves to obtain a modified abrasive, and then further comprising: After the chemical modification reaction is completed, the modified abrasive is separated from the unreacted silane coupling agent by centrifugal separation; The modified abrasive was washed several times with deionized water to remove unreacted silane coupling agent; The washed modified abrasive is dried in a vacuum drying oven at 80-120° C. for 12-24 hours to form a modified abrasive having a functional layer.

4. The method for preparing a rough polishing liquid for diamond substrate according to claim 1, characterized in that: The modified abrasive obtained is added into a stirring container, deionized water is added for preliminary dispersion to form an abrasive dispersion, an oxidant and a dispersant are then added into the abrasive dispersion in a preset ratio, and ultrasonic stirring is used to form a polishing liquid, specifically comprising: The obtained modified abrasive is measured according to the second preset mass ratio, and slowly added into a stirring container, and deionized water pre-cooled to 4-10° C. is slowly added into the stirring container, while the temperature is maintained in the range of 15-25° C., and preliminary dispersion is performed to form an abrasive dispersion liquid; Adding an oxidant and a dispersant according to a preset molar ratio; wherein the oxidant is hydrogen peroxide and the dispersant is a bio-based polymer; A dual-frequency ultrasonic device is used to perform ultrasonic-assisted stirring on the abrasive dispersion to form a polishing solution; the reaction conditions are set to alternately act at a low frequency of 20-40 kHz and a high frequency of 100-200 kHz, and the ultrasonic treatment time is 30-60 minutes.

5. The method for preparing a rough polishing liquid for diamond substrate according to claim 4, characterized in that: During the ultrasonic stirring process, the particle size distribution of the modified abrasive in the polishing liquid is monitored in real time by an online particle size analyzer, and the ultrasonic power and processing time are automatically adjusted according to the real-time monitored particle size distribution, specifically including: During the ultrasonic stirring process, a laser scattering particle size analyzer is used to monitor the particle size distribution of the polishing liquid in real time; Setting preset particle size distribution standard parameters, wherein the particle size distribution standard parameters include particle size range, average particle size and particle size distribution width; The particle size distribution data monitored by the laser scattering particle size analyzer is transmitted to the central control unit through the control system, and the central control unit analyzes the deviation between the particle size distribution data and the particle size distribution standard parameters based on the built-in feedback control algorithm; When the real-time monitored particle size distribution data deviates from the particle size distribution standard parameter, the control system sets an adjustment strategy for the power output of the dual-frequency ultrasonic device according to the deviation value; The ultrasonic power and processing time are automatically adjusted according to the power output adjustment strategy.

6. The method for preparing a rough polishing liquid for diamond substrate according to claim 4, characterized in that: The control system sets an adjustment strategy for the power output of the dual-frequency ultrasonic device according to the deviation value, specifically including: Define the real-time monitored particle size distribution deviation ΔD, where ΔD = D_actual - D_target; D_actual is the average particle size obtained by real-time monitoring, and D_target is the preset particle size distribution standard parameter; According to the size and direction of the particle size deviation ΔD, formulate an adjustment strategy for the ultrasonic power output; The functional relationship between the ultrasonic power adjustment ΔP and the particle size deviation ΔD was established, and the linear model ΔP = K_p ×ΔD was adopted; where ΔP is the ultrasonic power adjustment and K_p is the power adjustment coefficient; Calculate the power adjustment amounts ΔP_low and ΔP_high of the low-frequency and high-frequency ultrasonic waves respectively, and set the adjustment proportional coefficient β, ΔP_low = β × ΔP, ΔP_high = (1 - β) × ΔP.

7. The method for preparing a rough polishing liquid for diamond substrate according to claim 1, characterized in that: The stepwise titration method is used to add a pH regulator to the polishing liquid to adjust the pH value to a range of 6-9, specifically comprising: An online pH monitoring instrument is installed in the stirring container to monitor the pH value of the polishing liquid in real time; Select a weakly acidic or weakly alkaline pH regulator, wherein the pH regulator is an inorganic acid or an inorganic base; titrating by a stepwise titration method using an automatic titration device, wherein the stepwise titration method includes setting an initial dropping speed of the pH adjuster to a higher value, and then adding the pH adjuster dropwise to the polishing liquid at a preset constant micro flow rate; During the titration process, the pH change trend of the polishing liquid is obtained in real time through an online pH monitoring instrument, and the dripping speed and dripping amount of the pH adjuster are dynamically adjusted according to the degree to which the pH value approaches the target range.

8. The method for preparing a rough polishing liquid for diamond substrate according to claim 7, characterized in that: The pH dynamic adjustment process specifically includes: When the pH value is significantly different from the target range, maintain a higher drop rate; When the pH value gradually approaches the lower or upper limit of the target range, gradually reduce the dripping speed.

9. A rough polishing liquid for diamond substrates, characterized in that: The rough polishing liquid is prepared by the method for preparing a rough polishing liquid for a diamond substrate according to any one of claims 1 to 8, wherein the rough polishing liquid comprises: A modified abrasive, wherein the modified abrasive is made of nano-aluminum oxide or silicon carbide as an abrasive substrate, the abrasive substrate is mixed with a silane coupling agent, and a functional layer is formed on the surface of the modified abrasive through chemical modification; Deionized water, used to preliminarily disperse the modified abrasive to form an abrasive dispersion; an oxidizing agent, added to the abrasive dispersion in a predetermined proportion; A dispersant is added to the abrasive dispersion according to a preset ratio; The pH adjuster is added by gradual titration to adjust the pH value of the polishing liquid to a range of 6-9.

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