Polishing solution with self-lubricating function and preparation method thereof

Abstract

The invention relates to the technical field of polishing, in particular to a polishing solution with a self-lubricating function and a preparation method thereof. The invention relates to a polishing solution with a self-lubricating function. The polishing solution is prepared from the following raw materials: a grinding material, a thermal response microcapsule, a dispersing agent, an oxidizing agent, a pH regulator, a defoaming agent and Tween 80, wherein the thermal response microcapsule comprises an inner core and a shell, the inner core is molybdenum disulfide, and the shell is a temperature-sensitive polymer. The polishing solution with a self-lubricating function, which is prepared by preparing the thermal response microcapsules and preparing the polishing solution in an accurate proportion, has the advantages that the friction coefficient and the scratch risk are remarkably reduced, and the polishing effect is improved; the problems of scratching, temperature rise, uniformity and consumable service life in the polishing field are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polishing, in particular to a polishing liquid with self-lubricating function and a preparation method thereof. BACKGROUND

[0002] The polishing liquid, also known as grinding liquid or chemical mechanical polishing liquid, is a key liquid processing medium, which is widely used in the precise surface treatment process of various materials, especially in the occasions pursuing ultra-smooth, low-damage and high-flatness surface. Its core function is to remove the micro-protrusions on the material surface through the synergistic effect of chemical action such as dissolution, softening and passivation and mechanical action such as micro-cutting and friction, so as to realize the planarization, thinning, mirror finishing and removal of surface scratches, oxidation layer, processing metamorphic layer and other defects of the material.

[0003] The basic composition of the polishing liquid usually includes: abrasive particles, such as silica, nano-alumina, cerium oxide, diamond, silicon carbide, etc., which provide mechanical cutting force. Dispersion medium: usually water or organic solvent, which carries and disperses other components. Chemical additives: such as oxidizing agent, complexing agent, corrosion inhibitor, pH regulator, etc., which adjust the chemical reaction of the polishing process. Surfactants and dispersants: maintain stable suspension of abrasive particles and prevent agglomeration and sedimentation.

[0004] Common polishing liquid products and application fields include: semiconductor manufacturing: CMP polishing of silicon wafers, copper-tantalum interconnection layer, shallow trench isolation, polysilicon, dielectric layer. Optical elements: precise polishing of glass lenses, prisms, wafers, sapphire covers, laser crystals, etc. Metal processing: mirror polishing of non-ferrous metals such as stainless steel, copper, aluminum, hard alloy, etc. Storage hard disk: polishing of aluminum, glass, etc. hard disk substrate. Gem processing: polishing of jade, agate, etc.

[0005] Although polishing liquid is indispensable in precision machining, the existing technology still faces a series of challenges and limitations in practical application, mainly including: ① surface damage caused by insufficient lubricity: in the process of mechanical friction of high-speed polishing, it is often difficult for traditional polishing liquid to form a fully effective lubricating film between abrasive particles and workpiece surface, abrasive particles and polishing pad, which will lead to an increase in scratches and micro-defects, a decrease in polishing uniformity, an increase in polishing pad wear, and an accumulation of friction heat. ② Challenge of abrasive dispersion stability: nano-sized abrasive particles are prone to agglomeration and sedimentation, leading to unstable performance of the polishing liquid, affecting the uniformity of material removal rate and the repeatability of surface quality; existing dispersants may fail under high shear and long-term operation. ③ Cooling efficiency limitation: the specific heat capacity and thermal conductivity of traditional water-based polishing liquid are limited, and the heat generated by friction during high-intensity polishing may not be effectively removed in time, leading to excessive local temperature rise. ④ Chemical component balance problem: in the pursuit of high material removal rate, strong oxidizing or corrosive chemicals are often needed, which may conflict with the requirements of lubrication and corrosion inhibition, increasing the complexity of formula design and the potential corrosion risk to equipment / workpiece. ⑤ Environmental and cost pressure: high-performance additives such as certain organic solvents and fluorine-containing surfactants or difficult-to-handle abrasives may cause environmental burden or high cost problems.

[0006] In view of the core pain point of insufficient lubricity of existing polishing liquid and the problems of surface damage, poor uniformity, fast polishing pad wear, and high temperature rise caused thereby, it is urgent to develop a polishing liquid with self-lubricating function and a preparation method thereof. SUMMARY

[0007] In order to solve the problems of surface damage, poor uniformity, fast polishing pad wear, and high temperature rise caused by insufficient lubricity of polishing liquid, the present application provides a polishing liquid with self-lubricating function and a preparation method thereof, to achieve efficient and high-quality polishing effect.

[0008] In a first aspect, the present application provides a polishing liquid with self-lubricating function, which adopts the following technical solution: A polishing liquid with self-lubricating function, comprising the following raw materials prepared by weight percentage: abrasive 25-35%, thermal response microcapsule 5-10%, dispersant 3-5%, oxidizing agent 0.3-0.8%, pH adjuster 0.5-1.2%, defoamer 0.01-0.05%, Tween 80 0.8-1.2%, and the balance is deionized water; wherein the thermal response microcapsule comprises a core and a shell, the core is molybdenum disulfide, and the shell is a temperature-sensitive polymer.

[0009] The scheme solves the core pain points such as scratching, temperature rise and short service life of the polishing pad caused by the insufficient lubrication performance of the traditional polishing liquid through the thermal response microcapsule and precise component synergy. Traditional lubricants such as PEG are consumed in the early stage of polishing and cannot continue to take effect in the high-temperature friction zone. The temperature-sensitive shell of the thermal response microcapsule realizes on-demand lubrication, and the area with high friction heat releases the lubricant preferentially. When the temperature is greater than 40 DEG C, the microcapsule breaks, and the molybdenum disulfide spreads in situ on the friction interface to form an ultra-thin lubricating film. The nano-lubricant fills the surface micro-convex body to avoid direct abrasives scratching; the dispersant synchronously stabilizes the abrasives and the microcapsule.

[0010] A polishing liquid with self-lubricating function is prepared from the following raw materials in percentage by weight: abrasives 28-32%, thermal response microcapsule 6-8.5%, dispersant 3.8-4.5%, oxidizing agent 0.4-0.7%, pH adjuster 0.7-1.0%, defoamer 0.02-0.04%, Tween 80 0.9-1.1%, and the balance is deionized water; wherein the thermal response microcapsule comprises a core and a shell, the core is molybdenum disulfide, and the shell is a temperature-sensitive polymer.

[0011] Preferably, the abrasives are one or a mixture of several of nano-cerium oxide, nano-silicon dioxide, nano-aluminum oxide or nano-zirconium oxide, which are ground to D50=80-90nm by a sand mill.

[0012] Preferably, the abrasives are nano-cerium oxide, and the proportion of cubic crystal phase crystal face is ≥60%.

[0013] By adopting the above scheme, nano-cerium oxide is the preferred abrasive for high-end semiconductor polishing, which realizes atomic-level flatness and zero defects by virtue of the crystal face activity and particle size precision.

[0014] Preferably, in the thermal response microcapsule: the number of layers of the core molybdenum disulfide is ≤5 layers, the lateral size is 50-100nm, and the S / Mo molar ratio is ≥1.98; the shell temperature-sensitive polymer is a PDEAAM-co-AAm copolymer, the lower critical solution temperature is 38-42 DEG C, the thickness is 20-50nm, and the crosslinking degree is 5-8%.

[0015] By adopting the above scheme, the monomer DEAAM with a low critical solution temperature is creatively selected as the main component of the microcapsule shell and polymerized with AAm to form a temperature-sensitive polymer PDEAAM-co-AAm. The lower critical solution temperature of the polymer precisely matches the polishing interface temperature, which is usually 40-45 DEG C. When the interface temperature is greater than the lower critical solution temperature, the polymer shell shrinks and breaks, and the molybdenum disulfide is released in situ to form an ultra-lubricating film on the friction interface.

[0016] Preferably, the dispersant is one of ammonium polyacrylate homopolymer, sodium epoxy succinate, acrylic acid-maleic anhydride copolymer, and ammonium polyacrylate-acrylate copolymer.

[0017] Preferably, the dispersant is a polyammonium acrylate-acrylate copolymer with a molecular weight of 8000-12000, a molecular weight distribution index (PDI) ≤ 1.3, and a carboxyl density ≥ 4.5 mmol / g.

[0018] Preferably, the polyammonium acrylate-acrylate copolymer is prepared by the following method: acrylic acid, butyl acrylate, and hydroxyethyl acrylate are mixed in a mass ratio of (60-70):(20-30):(5-10) to obtain a monomer mixture; 30-40% by mass of deionized water is added to the monomer mixture; high-speed shear emulsification is carried out at 5000 rpm for 20 min to form a monomer emulsion with a droplet D90 particle size ≤500 nm; the monomer emulsion is transferred to a reaction vessel and heated to 80°C; ammonium persulfate initiator is added and reacted for 30 min; chain transfer agent is then added dropwise; the temperature is lowered to 40°C, and ammonia is added dropwise to adjust the pH to 7.0-7.5; unreacted monomers are removed by thin-film evaporation to make the residual acrylic acid ≤0.1%; and the mixture is concentrated under vacuum to a solid content of 40%.

[0019] Preferably, the dispersant is ammonium polyacrylate-acrylate copolymer, the initiator is ammonium persulfate, and the total amount is 0.5-1.5% of the mass of the monomer mixture; the chain transfer agent is mercaptoacetic acid, and the amount is 0.1-0.3% of the mass of the monomer mixture; the reaction is carried out at 80°C for 3 hours, and the monomer conversion rate is ≥98%.

[0020] Preferably, the oxidant is urea peroxide; urea peroxide releases H2O2 slowly at low temperatures, avoiding premature microcapsule rupture.

[0021] Preferably, the pH adjuster is 25% ammonia solution.

[0022] By adopting the above scheme, the pH adjuster is 25% ammonia water, which evaporates after polishing without leaving any residue when heated. The pH value of 8.0-8.5 maintains the high activity of cerium oxide abrasive, while the pH is adjusted to a weakly alkaline level of 8.0-8.5, which is beneficial for polishing metals such as copper and nickel, as well as semiconductor materials.

[0023] Preferably, the defoamer is polyether-modified silicone oil.

[0024] By adopting the above scheme, polyether-modified silicone oil suppresses foam generated by high-speed stirring and polishing, while reducing surface tension and avoiding air resistance at the interface between microcapsules and abrasives. This avoids the problem of hydrophobic points on the wafer surface that is easily caused by using traditional silicone oil.

[0025] Secondly, this application provides a method for preparing a polishing fluid with self-lubricating function, using the following technical solution: S1 Preparation of thermoresponsive microcapsules: Molybdenum disulfide was dispersed in cyclohexane, and DEAAM, AAM, and crosslinking agent PEGDA were added to form an oil phase; a polyethylene glycol-maleic anhydride mixture was dissolved in water to form an aqueous phase; the oil phase was injected into the aqueous phase, and emulsified by high-speed shearing to form an emulsion; the temperature was raised, and azobisisobutyramidine hydrochloride initiator was added dropwise; the polymerization reaction was carried out for 5 hours; the thermoresponsive microcapsule powder was obtained by spray drying. S2 Preparation of polishing solution: Add the thermally responsive microcapsule powder from step S1 to Tween80 and deionized water, and disperse by ultrasonication; then add abrasive, dispersant, and oxidant, mix, and stir for 30 minutes; add pH adjuster to adjust pH to 8.0-8.5, add defoamer, mix well, and filter.

[0026] By employing the above scheme, the dual effects of microencapsulation technology and precise triggering of release are achieved. During polishing, the friction between the tool and the workpiece generates localized high temperatures. When the temperature reaches the phase transition temperature of the microcapsule polymer shell, the permeability or mechanical strength of the shell changes, prompting the release of molybdenum disulfide inside. Simultaneously, the microcapsule shell physically isolates the molybdenum disulfide particles from other components in the polishing slurry, effectively preventing the aggregation and sedimentation of molybdenum disulfide itself, as well as partial oxidation failure caused by possible reactions with oxidants. This solves the problems of lubrication failure, severe scratches, and rapid wear of polishing pads in traditional polishing slurries. Grinding the abrasive to a narrow distribution range of D50=80-90nm is crucial for obtaining a high-precision, low-damage polished surface. Sand milling is an effective method. Using Tween80 surfactant in conjunction with ultrasonic dispersion ensures that the microcapsules are fully deagglomerated and stably dispersed before being added to the polishing slurry system. The abrasive dispersion and microcapsule dispersion are prepared separately, then mixed and stirred with other components to adjust the pH, and finally filtered to ensure the stability of each component before mixing and reduce uncertainties during mixing.

[0027] Preferably, in step S1, the thermally responsive microcapsules are prepared as follows: 7-9.5 parts of molybdenum disulfide are dispersed in 400 parts of cyclohexane, and 60-70 parts of DEAAM, 6.5-7.8 parts of AAM, and crosslinking agent PEGDA are added. The mixture is magnetically stirred at 500 rpm for 20 min to form an oil phase. 19-21 parts of a polyethylene glycol-maleic anhydride mixture are dissolved in 600 parts of water, and 0.1M NaOH is added dropwise to adjust the pH to 6.8 to form an aqueous phase. The oil phase is injected into the aqueous phase, emulsified at 5000 rpm for 5 min, homogenized in a homogenizer at 140-160 MPa for 3 cycles to form an emulsion, heated to 60-65℃, purged with nitrogen for 30 min, and an initiator azobisisobutyramidine hydrochloride aqueous solution is added dropwise at a rate of 1 mL / min. The polymerization reaction is carried out for 4-6 h, and the mixture is rapidly cooled to 10℃ in an ice bath. The precipitate is discarded by centrifugation, and the mixture is frozen at -20℃ for 10-12 h. The microcapsule powder is obtained by spray drying.

[0028] By employing the above scheme, AAM is used as the comonomer, forming a crosslinked network with a certain degree of toughness with PEGDA crosslinking agent. The introduction of a hydrophilic polyethylene glycol-maleic anhydride mixture into the outer layer increases the hydrophilicity of the microcapsules, contributing to their stable dispersion in aqueous polishing solutions. The DEAAM shell precisely responds to the frictional heat of polishing; the PEGDA crosslinked network with a crosslinking degree of 5-8% provides mechanical strength, with a breakage rate of <1% under pre-release shear at 10000 rpm; it undergoes directional rupture under the synergistic effect of temperature >40℃ and shear force, delaying the release time. Simultaneously, the molybdenum disulfide in the thermally responsive microcapsules is less prone to degradation or loss of lubricating properties during storage, extending the shelf life of the polishing solution; as a single unit, the thermally responsive microcapsules' dispersion behavior is more easily controlled through Tween 80 and ultrasound, contributing to a more stable and homogeneous system in the polishing solution.

[0029] Preferably, in step S1, the polyethylene glycol-maleic anhydride mixture is mixed at a molar ratio of 1:1, and the polyethylene glycol is PEG 400.

[0030] Preferably, in step S1, the amount of crosslinking agent PEGDA added is 5-8% of the total mass of DEAAM and AAM.

[0031] Preferably, in step S1, the spray drying conditions are: inlet temperature 160-170℃, outlet temperature 65-75℃, and inert gas protection.

[0032] The powder obtained by spray drying is easy to store, transport, and precisely add and disperse in subsequent polishing solutions, which is more convenient and stable than using emulsions directly.

[0033] Preferably, in step S1: the azobisisobutyramidine hydrochloride aqueous solution is prepared by adding 4-6 parts of azobisisobutyramidine hydrochloride to 100 parts of deionized water and mixing them evenly.

[0034] By adopting the above scheme, the microcapsules prepared by this scheme have a uniform particle size of 200-210nm, a high encapsulation rate of 94.3%, and a precise temperature control rupture temperature of 40.2℃, which fully meets the self-lubricating requirements of the polishing fluid. The process reproducibility was verified: the rupture temperature deviation was <±0.3℃, and the molybdenum disulfide release rate was >98%.

[0035] In summary, this application has the following beneficial effects: The self-lubricating polishing slurry prepared in this application was used to prepare thermally responsive microcapsules loaded with the solid lubricant molybdenum disulfide. These microcapsules were cleverly integrated into the polishing slurry system, significantly reducing the coefficient of friction and the risk of scratches, and improving surface quality. The microcapsules protect the molybdenum disulfide, extend its shelf life, and improve dispersion stability. They also work synergistically with nano-abrasives to enhance the polishing effect. This process solves the problems of scratches, temperature rise, uniformity, and consumable life in the polishing field.

[0036] The polishing slurry with self-lubricating function prepared by this application reduces the scratch depth during use, improves the yield of high-end chips, extends the life of polishing pads, reduces intra-wafer non-uniformity, reduces energy consumption and meets emission standards, which is in line with the development trend of green manufacturing. Detailed Implementation

[0037] The technical solution of this application is further illustrated by specific embodiments below. These specific embodiments do not represent a limitation on the scope of protection of this application. Any non-essential modifications and adjustments made by others based on the concept of this application still fall within the scope of protection of this application.

[0038] Unless otherwise specified, the experimental methods shown in the following examples are conventional methods. All reagents and materials shown are commercially available products.

[0039] Polyethylene glycol: Jiangsu Haian Petrochemical Plant, product specification: PEG-400; Maleic anhydride: Anaiji Chemical, CAS: 108-31-6, Product Code: A010576; N,N-Diethylacrylamide (abbreviated DEAAM); Wuhan Jixin Yibang Biotechnology Co., Ltd., CAS: 2675-94-7, Product No.: 20240702; Acrylamide (abbreviation AAM); Shanghai Maclean Biochemical Technology Co., Ltd., CAS: 122775-19-3, Product Code: A874710; Polyethylene glycol diacrylate (PEGDA); Shanghai Huayuan Biochemical Technology Co., Ltd., CAS: 26570-48-9; Nano-cerium oxide: Hangzhou Jiupeng New Materials Co., Ltd., CAS: 1306-38-3, Item No.: CY-CE02; Molybdenum disulfide: Henan Shuangjie Chemical Co., Ltd., CAS: 569-70-63; Butyl acrylate: Shandong Jinyufeng New Material Co., Ltd., CAS: 141-32-2, Item No.: JYF-11; Hydroxyethyl acrylate: Shandong Ruifeng New Materials Co., Ltd., Item No.: JH062003; Polyether modified silicone oil: Yantai Hanbang New Materials Co., Ltd., Model: 204, Item No.: 01.

[0040] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0041] Preparation Example

[0042] Preparation Example 1: Preparation of Ammonium Polyacrylate-Acrylate Copolymer 650g of acrylic acid, 250g of butyl acrylate, and 80g of hydroxyethyl acrylate were mixed to obtain a monomer mixture, and 343mL of deionized water was added. The mixture was then subjected to high-speed shear emulsification at 5000rpm for 20min to form a monomer emulsion with a droplet D90 diameter ≤500nm. The monomer emulsion was transferred to a reaction vessel and heated to 80℃. 9.8g of ammonium persulfate initiator was added, and the reaction was allowed to proceed for 30min. Then, 1.96g of mercaptoacetic acid chain transfer agent was added dropwise, and the reaction was maintained at 80℃ for 3h until the monomer conversion rate was ≥98%. The mixture was then cooled to 40℃, and ammonia was added dropwise to adjust the pH to 7.0. Unreacted monomers were removed by thin-film evaporation, leaving residual acrylic acid ≤0.1%. The mixture was then concentrated under vacuum to a solid content of 40%.

[0043] Preparation Example 2: Preparation of Ammonium Polyacrylate-Acrylate Copolymer 600g of acrylic acid, 200g of butyl acrylate, and 50g of hydroxyethyl acrylate were mixed to obtain a monomer mixture, and 300mL of deionized water was added. The mixture was then subjected to high-speed shear emulsification at 5000rpm for 20min to form a monomer emulsion with a droplet D90 diameter ≤500nm. The monomer emulsion was transferred to a reactor and heated to 80℃. 5g of ammonium persulfate initiator was added, and the reaction was allowed to proceed for 30min. Then, 1.0g of mercaptoacetic acid chain transfer agent was added dropwise, and the reaction was maintained at 80℃ for 3h until the monomer conversion rate was ≥98%. The temperature was then lowered to 40℃, and ammonia was added dropwise to adjust the pH to 7.0. Unreacted monomers were removed by thin-film evaporation, leaving residual acrylic acid ≤0.1%. The mixture was then concentrated under vacuum to a solid content of 40%.

[0044] Preparation Example 3: Preparation of Ammonium Polyacrylate-Acrylate Copolymer 700g acrylic acid, 300g butyl acrylate, and 100g hydroxyethyl acrylate were mixed to obtain a monomer mixture, and 400mL of deionized water was added. The mixture was then subjected to high-speed shear emulsification at 5000rpm for 20min to form a monomer emulsion with a droplet D90 diameter ≤500nm. The monomer emulsion was transferred to a reactor and heated to 80℃. 15g of ammonium persulfate initiator was added, and the reaction was allowed to proceed for 30min. Then, 3.0g of mercaptoacetic acid chain transfer agent was added dropwise, and the reaction was maintained at 80℃ for 3h until the monomer conversion rate was ≥98%. The mixture was then cooled to 40℃, and ammonia was added dropwise to adjust the pH to 7.0. Unreacted monomers were removed by thin-film evaporation, leaving residual acrylic acid ≤0.1%. The mixture was then concentrated under vacuum to a solid content of 40%. Example Example 1

[0045] A method for preparing a polishing fluid with self-lubricating function is as follows: Preparation of thermoresponsive microcapsules (S1): 8.2 g of molybdenum disulfide was dispersed in 400 mL of cyclohexane, and 66 g of DEAAM, 7.1 g of AAm, and 4.7 g of crosslinking agent PEGDA were added. The mixture was magnetically stirred at 500 rpm for 20 min to form an oil phase. 20 g of polyethylene glycol-maleic anhydride mixture was dissolved in 600 mL of water, and 0.1 M NaOH was added dropwise to adjust the pH to 6.8 to form an aqueous phase. The oil phase was injected into the aqueous phase, and the mixture was emulsified at 5000 rpm for 5 min. The emulsion was homogenized for 3 cycles at 150 MPa using a homogenizer. The temperature was raised to 65 °C, and nitrogen was purged for 30 min. Azobisisobutyramidine hydrochloride aqueous solution was added dropwise at a rate of 1 mL / min. The polymerization reaction was carried out for 5 h, and the mixture was rapidly cooled to 10 °C in an ice bath. The precipitate was discarded by centrifugation, and the mixture was frozen at -20 °C for 12 h. The mixture was then spray-dried at an inlet temperature of 170 °C and an outlet temperature of 65 °C to obtain thermoresponsive microcapsule powder. S2 Preparation of polishing solution: 70g of thermally responsive microcapsule powder from step S1 is added to 10g of Tween 80 and 557.5g of deionized water and ultrasonically dispersed; then 307g of nano-cerium oxide, 41g of ammonium polyacrylate-acrylate copolymer, and 5.2g of hydrogen peroxide are added and stirred for 30min; 9g of 25% ammonia water is added to adjust the pH, and 0.3g of polyether modified silicone oil is added, mixed and filtered.

[0046] The azobisisobutyramidine hydrochloride aqueous solution is prepared by adding 5g of azobisisobutyramidine hydrochloride to 100mL of deionized water and mixing thoroughly.

[0047] The polyethylene glycol-maleic anhydride mixture is a mixture of 20g polyethylene glycol and 4.9g maleic anhydride. Example 2

[0048] A method for preparing a polishing fluid with self-lubricating function is as follows: Preparation of thermoresponsive microcapsules (S1): 7g of molybdenum disulfide was dispersed in 400mL of cyclohexane, and 60g of DEAAM, 6.5g of AAM, and 3.3g of crosslinking agent PEGDA were added. The mixture was magnetically stirred at 500rpm for 20min to form an oil phase. 19g of polyethylene glycol-maleic anhydride mixture was dissolved in 600mL of water, and 0.1M NaOH was added dropwise to adjust the pH to 6.8 to form an aqueous phase. The oil phase was injected into the aqueous phase, emulsified at 5000rpm for 5min, and homogenized for 3 cycles at 140MPa in a homogenizer to form an emulsion. The temperature was raised to 60℃, and nitrogen was purged for 30min. Azobisisobutyramidine hydrochloride aqueous solution was added dropwise at a rate of 1mL / min, and the polymerization reaction was carried out for 4h. The mixture was then rapidly cooled to 10℃ in an ice bath. The precipitate was discarded by centrifugation, and the mixture was frozen at -20℃ for 10h. The mixture was then spray-dried at an inlet temperature of 160℃ and an outlet temperature of 65℃ to obtain thermoresponsive microcapsule powder. S2 Preparation of polishing solution: 396.1g of thermally responsive microcapsule powder from step S1 is added to 8g of Tween80 and 603.9g of water and ultrasonically dispersed; 250g of nano-cerium oxide, 30g of ammonium polyacrylate-acrylate copolymer, and 3g of hydrogen peroxide are added and stirred for 30min; 5g of 25% ammonia water is added to adjust the pH to 8.0-8.5, and 0.1g of polyether modified silicone oil is added, mixed and filtered.

[0049] The aqueous solution of azobisisobutyramidine hydrochloride is prepared by adding 4g of azobisisobutyramidine hydrochloride to 100mL of deionized water and mixing thoroughly. Example 3

[0050] A method for preparing a polishing fluid with self-lubricating function is as follows: Preparation of thermoresponsive microcapsules (S1): 9.5 g of molybdenum disulfide was dispersed in 400 mL of cyclohexane, and 70 g of DEAAM, 7.8 g of AAm, and 6.2 g of crosslinking agent PEGDA were added. The mixture was magnetically stirred at 500 rpm for 20 min to form an oil phase. 21 g of polyethylene glycol-maleic anhydride mixture was dissolved in 600 mL of water, and 0.1 M NaOH was added dropwise to adjust the pH to 6.8 to form an aqueous phase. The oil phase was injected into the aqueous phase, emulsified at 5000 rpm for 5 min, and homogenized for 3 cycles at 160 MPa in a homogenizer to form an emulsion. The temperature was raised to 65 °C, and nitrogen was purged for 30 min. Azobisisobutyramidine hydrochloride aqueous solution was added dropwise at a rate of 1 mL / min. The polymerization reaction was carried out for 6 h, and the mixture was rapidly cooled to 10 °C in an ice bath. The precipitate was discarded by centrifugation, and the mixture was frozen at -20 °C for 12 h. The mixture was then spray-dried at an inlet temperature of 170 °C and an outlet temperature of 75 °C to obtain thermoresponsive microcapsule powder. S2 Preparation of polishing solution: Add 12g Tween 80 and 517.5g water to 50g of thermally responsive microcapsule powder from step S1, and disperse by ultrasonication; add 350g of nano-cerium oxide, 50g of ammonium polyacrylate-acrylate copolymer, and 8g of hydrogen peroxide urea, and stir for 30min; add 12g of 25% ammonia water to adjust the pH to 8.0-8.5, add 0.5g of polyether modified silicone oil, mix well and filter.

[0051] The aqueous solution of azobisisobutyramidine hydrochloride is prepared by adding 6g of azobisisobutyramidine hydrochloride to 100mL of deionized water and mixing thoroughly. Example 4

[0052] A method for preparing a polishing fluid with self-lubricating function is as follows: Preparation of thermoresponsive microcapsules (S1): 7.5 g molybdenum disulfide was dispersed in 400 mL of cyclohexane, and 62 g DEAAM, 7.5 g AAm, and 4.2 g crosslinking agent PEGDA were added. The mixture was magnetically stirred at 500 rpm for 20 min to form an oil phase. 19.5 g of polyethylene glycol-maleic anhydride mixture was dissolved in 600 mL of water, and 0.1 M NaOH was added dropwise to adjust the pH to 6.8 to form an aqueous phase. The oil phase was injected into the aqueous phase, emulsified at 5000 rpm for 5 min, and homogenized for 3 cycles at 160 MPa using a homogenizer to form an emulsion. The temperature was raised to 65 °C, and nitrogen was purged for 30 min. Azobisisobutyramidine hydrochloride aqueous solution was added dropwise at a rate of 1 mL / min. The polymerization reaction was carried out for 6 h, and the mixture was rapidly cooled to 10 °C in an ice bath. The precipitate was discarded by centrifugation, and the mixture was frozen at -20 °C for 10 h. The mixture was then spray-dried at an inlet temperature of 160 °C and an outlet temperature of 75 °C to obtain thermoresponsive microcapsule powder. S2 Preparation of polishing solution: Add 11g Tween 80 and 593.8g water to 60g of thermally responsive microcapsule powder from step S1, and disperse by ultrasonication; add 280g of nano-cerium oxide, 38g of ammonium polyacrylate-acrylate copolymer, and 7g of hydrogen peroxide urea, and stir for 30min; add 10g of 25% ammonia water to adjust the pH to 8.0-8.5, add 0.2g of polyether modified silicone oil, mix well and filter.

[0053] The aqueous solution of azobisisobutyramidine hydrochloride is prepared by adding 6g of azobisisobutyramidine hydrochloride to 100mL of deionized water and mixing thoroughly. Example 5

[0054] A method for preparing a polishing fluid with self-lubricating function is as follows: Preparation of thermoresponsive microcapsules (S1): 8.5 g molybdenum disulfide was dispersed in 400 mL of cyclohexane, and 68 g DEAAM, 6.8 g AAm, and 5.2 g crosslinking agent PEGDA were added. The mixture was magnetically stirred at 500 rpm for 20 min to form an oil phase. 20.5 g of polyethylene glycol-maleic anhydride mixture was dissolved in 600 mL of water, and 0.1 M NaOH was added dropwise to adjust the pH to 6.8 to form an aqueous phase. The oil phase was injected into the aqueous phase, and the mixture was emulsified at 5000 rpm for 5 min. The emulsion was homogenized for 3 cycles at 160 MPa using a homogenizer. The temperature was raised to 65 °C, and nitrogen was purged for 30 min. Azobisisobutyramidine hydrochloride aqueous solution was added dropwise at a rate of 1 mL / min. The polymerization reaction was carried out for 5 h, and the mixture was rapidly cooled to 10 °C in an ice bath. The precipitate was discarded by centrifugation, and the mixture was frozen at -20 °C for 12 h. The mixture was then spray-dried at an inlet temperature of 160 °C and an outlet temperature of 75 °C to obtain thermoresponsive microcapsule powder. S2 Preparation of polishing solution: Add 9g Tween 80 and 529.6g water to 85g of thermally responsive microcapsule powder from step S1, and disperse by ultrasonication; add 320g of nano-cerium oxide, 45g of ammonium polyacrylate-acrylate copolymer, and 4g of hydrogen peroxide urea, and stir for 30min; add 7g of 25% ammonia water to adjust the pH to 8.0-8.5, add 0.4g of polyether modified silicone oil, mix well and filter.

[0055] The aqueous solution of azobisisobutyramidine hydrochloride is prepared by adding 5g of azobisisobutyramidine hydrochloride to 100mL of deionized water and mixing thoroughly.

[0056] Comparative Example

[0057] Comparative Example 1 Similar to Example 1, except that the abrasive is nano-silica and the dispersant is ammonium polyacrylate homopolymer.

[0058] Comparative Example 2 Similar to Example 1, except that the abrasive is nano-alumina and the dispersant is sodium epoxysuccinate.

[0059] Comparative Example 3 Similar to Example 1, except that the abrasive is nano-zirconia; the dispersant is an acrylic acid-maleic anhydride copolymer, wherein acrylic acid and maleic anhydride are mixed in a molar ratio of 1:1.

[0060] Comparative Example 4 Similar to Example 1, except that the molybdenum disulfide is not microencapsulated, and 70g of molybdenum disulfide is added directly to the raw material.

[0061] Comparative Example 5 Similar to Example 1, except that the temperature-sensitive polymer of the microcapsule shell is replaced with ordinary PNIPAM.

[0062] Comparative Example 6 Same as in Example 1, except that the dispersant is replaced with inefficient sodium polyacrylate.

[0063] Comparative Example 7 Similar to Example 1, except that Tween 80 is not added, and only water-dispersible microcapsules are used.

[0064] Performance testing

[0065] Performance tests were conducted on the self-lubricating polishing slurries prepared in Examples 1-5 and Comparative Examples 1-7. The test substrate was a 300mm silicon wafer. Polishing machine parameters were: pressure 3 psi, rotation speed 93 rpm, time 60 s, and flow rate 200 mL / min. Performance was assessed by scratch depth, coefficient of friction, wear rate, and polishing efficiency. Scratch depth was measured using a Bruker AFM at a scan rate of 1 Hz. Polishing efficiency was measured by the material removal rate (MRR) using an ellipsometry. Wear rate was measured by the polishing pad thickness loss using a laser thickness gauge, with an initial pad thickness of 1.27 mm and an endpoint of 1.00 mm. The test results are shown in Table 1.

[0066]

[0067] Table 1 shows that, among the polishing slurries with self-lubricating function prepared in Examples 1-5, Example 1 exhibited the best performance, with a scratch depth of 1.9±0.2 nm, a wear rate of 0.65 μm / piece, and an MRR of 285±8 nm / min. Comparative Examples 1, 2, and 3 also demonstrated excellent performance, with scratch depths ranging from 2.1 to 2.8 nm, friction coefficients from 0.069 to 0.078, and wear rates from 0.68 to 0.94 μm / piece, and MRRs from 270 to 282 nm / min. This indicates that the abrasive is one or a mixture of several of nano-cerium oxide, nano-silica, nano-alumina, or nano-zirconia, and the dispersant is one of ammonium polyacrylate homopolymer, sodium epoxy succinate, acrylic acid-maleic anhydride copolymer, or ammonium polyacrylate-acrylate copolymer, all of which exhibit good performance. Good lubricity allows for the application of greater pressure or the use of higher rotational speeds, while reducing thermal deformation or workpiece damage caused by frictional heat generation, potentially improving material removal rate while maintaining quality.

[0068] As shown in Table 1, the experimental data in Comparative Example 4, where molybdenum disulfide was not microencapsulated, easily agglomerated, resulting in a particle size >500 nm and a scratch depth of 12.5 ± 3.1 nm when directly scraping the surface. In Comparative Example 5, the temperature-sensitive polymer of the microcapsule shell was replaced with ordinary PNIPAM, with an LCST of 32°C, which was lower than the polishing temperature of 40°C. This premature release led to lubrication issues, with only 45% of the lubricant effectively covering the surface. In Comparative Example 6, the dispersant was changed to inefficient sodium polyacrylate, which had a large particle size and strong cutting force. The scratch depth was 8.2 ± 2.0 nm, causing stress-concentrated scratches. It could be used for rough polishing of metals but could not be used for fine polishing, resulting in a high defect rate. In Comparative Example 7, without the addition of Tween 80, only water was used to disperse the microcapsules. The microcapsule agglomeration >800 nm led to uneven release and decreased coverage.

[0069] The above experimental results show that the self-lubricating polishing slurry prepared in this application, along with the thermally responsive microcapsules loaded with the solid lubricant molybdenum disulfide, and their ingenious integration into the polishing slurry system, significantly reduces the coefficient of friction and the risk of scratches, and improves surface quality. The microcapsules protect MoS2, extend its shelf life, and improve dispersion stability. They also work synergistically with nano-abrasives to enhance the polishing effect. This solves the problems of scratches, temperature rise, uniformity, and consumable life in the polishing field.

[0070] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the present invention, they are protected by patent law.

Claims

1. A polishing fluid with self-lubricating function, characterized in that, It is prepared from the following raw materials by weight percentage: 25-35% abrasive, 5-10% thermally responsive microcapsules, 3-5% dispersant, 0.3-0.8% oxidant, 0.5-1.2% pH adjuster, 0.01-0.05% defoamer, 0.8-1.2% Tween 80, and the balance being deionized water; wherein, the thermally responsive microcapsules include a core and a shell, the core being molybdenum disulfide and the shell being a temperature-sensitive polymer.

2. The polishing liquid with self-lubricating function according to claim 1, characterized in that, The abrasive is one or a mixture of several of nano-cerium oxide, nano-silica, nano-alumina, or nano-zirconia, and is ground to D50=80-90nm by a sand mill.

3. The polishing fluid with self-lubricating function according to claim 1, characterized in that, The thermally responsive microcapsules contain: a core of molybdenum disulfide with ≤5 layers, a transverse dimension of 50-100 nm, and an S / Mo molar ratio ≥1.98; and a shell of thermosensitive polymer, PDEAAM-co-AAm copolymer, with a low critical melting temperature of 38-42 °C, a thickness of 20-50 nm, and a degree of crosslinking of 5-8%.

4. The polishing liquid with self-lubricating function according to claim 1, characterized in that, The dispersant is one of the following: ammonium polyacrylate homopolymer, sodium epoxy succinate, acrylic acid-maleic anhydride copolymer, and ammonium polyacrylate-acrylate copolymer.

5. The polishing fluid with self-lubricating function according to claim 4, characterized in that, The ammonium polyacrylate-acrylate copolymer is prepared by the following method: acrylic acid, butyl acrylate, and hydroxyethyl acrylate are mixed in a mass ratio of (60-70):(20-30):(5-10) to obtain a monomer mixture; 30-40% by mass of deionized water is added to the monomer mixture; high-speed shear emulsification is carried out at 5000 rpm for 20 min to form a monomer emulsion with a droplet D90 particle size ≤500 nm; the monomer emulsion is transferred to a reaction vessel and heated to 80°C; ammonium persulfate initiator is added and reacted for 30 min; chain transfer agent is then added dropwise; the temperature is lowered to 40°C, and ammonia is added dropwise to adjust the pH to 7.0-7.5; unreacted monomers are removed by thin-film evaporation to make the residual acrylic acid ≤0.1%; and the mixture is concentrated under vacuum to a solid content of 40%.

6. The polishing fluid with self-lubricating function according to claim 1, characterized in that, The defoamer is polyether-modified silicone oil; the pH adjuster is 25% ammonia water.

7. A method for preparing a polishing fluid with self-lubricating function as described in any one of claims 1-6, characterized in that, The following technical solution is adopted: S1 Preparation of thermoresponsive microcapsules: Molybdenum disulfide was dispersed in cyclohexane, and DEAAM, AAM, and crosslinking agent PEGDA were added to form an oil phase; a polyethylene glycol-maleic anhydride mixture was dissolved in water to form an aqueous phase; the oil phase was injected into the aqueous phase, and emulsified by high-speed shearing to form an emulsion; the temperature was raised, and azobisisobutyramidine hydrochloride initiator was added dropwise; the polymerization reaction was carried out for 5 hours; the thermoresponsive microcapsule powder was obtained by spray drying. S2 Preparation of polishing solution: Add the thermally responsive microcapsule powder from step S1 to Tween80 and deionized water, and disperse by ultrasonication; then add abrasive, dispersant, and oxidant, mix, and stir for 30 minutes; add pH adjuster to adjust pH to 8.0-8.5, add defoamer, mix well, and filter.

8. The method for preparing the polishing fluid with self-lubricating function according to claim 7, characterized in that, The preparation of thermoresponsive microcapsules in step S1 involves dispersing 7-9.5 parts of molybdenum disulfide in 400 parts of cyclohexane, adding 60-70 parts of DEAAM, 6.5-7.8 parts of AAM, and the crosslinking agent PEGDA, and dissolving by magnetic stirring at 500 rpm for 20 min to form an oil phase; dissolving 19-21 parts of a polyethylene glycol-maleic anhydride mixture in 600 parts of water, and adjusting the pH to 6.8 by adding 0.1M NaOH dropwise to form an aqueous phase; injecting the oil phase into the aqueous phase, emulsifying at 5000 rpm for 5 min, homogenizing for 3 cycles at 140-160 MPa using a homogenizer to form an emulsion, heating to 60-65℃, purging with nitrogen for 30 min, adding an initiator azobisisobutyramidine hydrochloride aqueous solution at a dropping rate of 1 mL / min, and polymerizing for 4-6 h; then rapidly cooling to 10℃ in an ice bath; centrifuging to discard the precipitate, freezing at -20℃ for 10-12 h, and spray drying to obtain microcapsule powder.

9. The method for preparing the polishing fluid with self-lubricating function according to claim 7, characterized in that, In step S1: the amount of crosslinking agent PEGDA added is 5-8% of the total mass of DEAAM and AAM.

10. The method for preparing the polishing fluid with self-lubricating function according to claim 7, characterized in that, In step S1, the spray drying conditions are: inlet temperature 160-170℃, outlet temperature 65-75℃, and inert gas protection.

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