Wafer polishing solution containing graphene nanosheets and preparation process of wafer polishing solution

Abstract

The invention relates to the technical field of grinding fluid, in particular to wafer polishing fluid containing graphene nanosheets and a preparation process of the wafer polishing fluid. A graphene modified abrasive; an oxidant; a complexing agent; a metal corrosion inhibitor; a pH adjusting agent; a dispersion stabilizer; an interface modifier; a defect repairing agent; a corrosion inhibition synergist; a wettability modifier; an anti-agglomeration agent; and deionized water. Through introduction of the graphene modified abrasive and multi-component collaborative design, the graphene modified abrasive polishing solution has high polishing efficiency, low corrosion rate and excellent dispersion stability, compared with a traditional polishing solution, the Cu / Co corrosion rate is reduced by 60% or above, the copper surface roughness Ra is smaller than or equal to 0.5 nm, polished wafers do not have obvious micro-scratches, and the lubricating property and the mechanical grinding property of graphene nanosheets are coordinated, so that the mechanical polishing effect is good. The copper / cobalt removal rate ratio is stabilized at 1: 1 + / -0.1, and the defects of dished pits and corrosion pits are effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of polishing slurry technology, specifically to a wafer polishing slurry containing graphene nanosheets and its preparation process. Background Technology

[0002] Wafer polishing slurry (chemical mechanical polishing slurry, CMP slurry) is a core consumable in the chemical mechanical polishing (CMP) process of semiconductor manufacturing. It is mainly used for ultra-precision planarization of wafer surfaces, especially in advanced 7nm / 5nm copper / cobalt interconnect processes. The performance of the polishing slurry directly determines the wafer surface quality, device yield, and reliability. Its core function is to remove wafer surface bumps, residual metal, and defects through the synergistic effect of chemical etching and mechanical polishing, achieving an atomically smooth planarized surface, providing a foundation for subsequent photolithography, deposition, and other processes.

[0003] However, traditional CMP polishing slurries for copper / cobalt interconnects typically consist of colloidal silica or alumina as single abrasives, combined with conventional oxidants and inhibitors, which have significant drawbacks: First, Cu / Co galvanic corrosion is a prominent issue, with the cobalt barrier layer easily over-corroded, leading to increased copper diffusion risk and higher device short-circuit rates. Second, the abrasives tend to agglomerate, forming micro-scratches on the wafer surface; in 7nm processes, the yield loss due to scratches can reach over 20%. Third, polishing selectivity is poor; the copper to cobalt removal rate ratio is difficult to maintain at 1:1, easily resulting in surface defects such as dish-shaped pits and etching pits. Fourth, dispersion stability is insufficient; after the polishing slurry has been left to stand for 48 hours, the delamination rate exceeds 5%, and there are large performance fluctuations between batches. Fifth, the wafer surface roughness is difficult to meet the requirements of advanced processes; after treatment with traditional polishing slurries, the copper surface roughness Ra ≥ 1.2nm, significantly increasing the risk of electron scattering.

[0004] Based on this, the present invention provides a wafer polishing slurry containing graphene nanosheets and its preparation method to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a wafer polishing slurry containing graphene nanosheets and its preparation process, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention proposes a wafer polishing slurry containing graphene nanosheets, which is composed of the following raw materials in parts by weight: abrasive matrix: 20-35 parts; graphene-modified abrasive: 5-12 parts; oxidant: 3-8 parts; complexing agent: 1.5-4 parts; metal corrosion inhibitor: 0.8-2.5 parts; pH adjuster: 0.5-1.8 parts; dispersant stabilizer: 0.3-1.2 parts; interface modifier: 0.2-0.9 parts; defect repair agent: 0.15-0.6 parts; corrosion inhibitor: 0.1-0.5 parts; wettability regulator: 0.08-0.3 parts; anti-agglomeration agent: 0.05-0.2 parts; deionized water: 30-45 parts.

[0007] Preferably, the abrasive matrix is ​​composed of colloidal silica and nano-alumina, wherein the colloidal silica comprises 18-32 parts and the nano-alumina comprises 2-3 parts.

[0008] Preferably, the graphene-modified abrasive is composed of silane coupling agent-modified graphene nanosheets and cerium oxide nanospheres, wherein the silane coupling agent-modified graphene nanosheets comprise 0.5-2 parts and the cerium oxide nanospheres comprise 4.5-10 parts.

[0009] Preferably, the oxidant is composed of hydrogen peroxide and ferric nitrate, wherein the hydrogen peroxide comprises 2-6 parts and the ferric nitrate comprises 1-2 parts.

[0010] Preferably, the complexing agent is composed of aminotriacetic acid, citric acid and disodium ethylenediaminetetraacetate, wherein the aminotriacetic acid is 0.5-1.5 parts, the citric acid is 0.4-1 parts, and the disodium ethylenediaminetetraacetate is 0.6-1.5 parts.

[0011] Preferably, the metal corrosion inhibitor is composed of benzotriazole, mercaptobenzothiazole and 2-mercaptobenzimidazole, wherein the benzotriazole content is 0.3-1 parts, the mercaptobenzothiazole content is 0.2-0.8 parts, and the 2-mercaptobenzimidazole content is 0.3-0.7 parts.

[0012] Preferably, the pH adjuster is composed of potassium hydroxide and boric acid, wherein the potassium hydroxide content is 0.3-1.2 parts and the boric acid content is 0.2-0.6 parts; the dispersion stabilizer is ammonium polyacrylate with a molecular weight of 8000-15000; and the interface modifier is a perfluorooctyl sulfonate ammonium type fluorocarbon surfactant, which is functionalized by grafting phosphate groups onto its hydrophilic end.

[0013] Preferably, the defect repair agent is nano-hydroxyapatite with a particle size of 20-50 nm; the corrosion inhibitor is sodium phytate; the wettability regulator is polyethylene glycol 400; and the anti-agglomeration agent is composed of sodium dodecylbenzenesulfonate and polyoxyethylene ether, wherein the sodium dodecylbenzenesulfonate is 0.03-0.12 parts and the polyoxyethylene ether is 0.02-0.08 parts.

[0014] Based on the above-mentioned wafer polishing slurry, the present invention also proposes a method for preparing a wafer polishing slurry containing graphene nanosheets, comprising the following steps: S1. 18-32 parts of colloidal silica and 2-3 parts of nano-alumina in the abrasive matrix are passed through an air-jet sieve to remove agglomerated particles. 0.5-2 parts of graphene nanosheets modified with silane coupling agent in the graphene-modified abrasive are added to 10-15 parts of deionized water and ultrasonically dispersed for 30 minutes at 25±3℃ using an ultrasonic disperser with a power of 300-500W and a frequency of 40kHz. 4.5-10 parts of nano-cerium oxide microspheres are added and ultrasonically dispersed for another 15 minutes, achieving a dispersion uniformity ≥99%. 2-6 parts of hydrogen peroxide and 1-2 parts of ferric nitrate are stored at a constant temperature of 20±2℃ to prevent decomposition. S2. The ultrasonically dispersed graphene-modified abrasive suspension and abrasive matrix are added to a high-speed mixing vessel and mixed in three stages: Coarse mixing: Stir at 500 rpm for 5 minutes to eliminate raw material accumulation; Fine mixing: Stir at 1200 r / min for 10 min, then add 0.5-1.5 parts of complexing agent aminotriacetic acid, 0.4-1 part of citric acid, and 0.6-1.5 parts of disodium ethylenediaminetetraacetate in sequence; Homogenization: Stir at 2000 r / min for 8 min, and monitor particle size distribution using an online laser particle size analyzer to ensure that the abrasive particle size variation coefficient is ≤5%; S3. Pump 0.3-1 parts of the metal corrosion inhibitor benzotriazole, 0.2-0.8 parts of mercaptobenzothiazole, 0.3-0.7 parts of 2-mercaptobenzimidazole and 5-8 parts of deionized water into a static mixer in a certain proportion, control the water temperature at 18-22℃, premix into a homogeneous solution, add 0.1-0.5 parts of the corrosion inhibitor sodium phytate, and inject in a pulsed manner at a pulse frequency of 10Hz to avoid excessive local concentration; S4. Add the mixture from step S2 and the premixed solution from step S3 into a mixing vessel and mix in two stages: First stage: Stir at 800 r / min for 4 min, add 0.3-1.2 parts of potassium hydroxide and 0.2-0.6 parts of boric acid to adjust the pH of the system to 8.5-9.5; Second stage: Stir at 1500 r / min for 6 min, then add the following components sequentially: dispersion stabilizer: ammonium polyacrylate 0.3-1.2 parts; interface modifier: ammonium perfluorooctyl sulfonate 0.2-0.9 parts; defect repair agent: nano hydroxyapatite 0.15-0.6 parts. The system viscosity is controlled to 5-8 using online viscosity feedback. Bye · s ; S5. Dissolve 0.08-0.3 parts of the wetting modifier polyethylene glycol 400, 0.03-0.12 parts of the anti-agglomeration agent sodium dodecylbenzenesulfonate, and 0.02-0.08 parts of polyoxyethylene ether in 15-22 parts of the remaining deionized water, and slowly add the solution dropwise to the mixing vessel. Reduce the speed to 600 r / min and stir for 3 min. Then add the oxidant pretreated in step S1 and continue stirring for 2 min. S6. Filter the mixed polishing slurry through a 0.2μm precision filter and send it into an aging tank for constant aging at 25℃ for 24h. Stir once every 6h during the process, at a speed of 300r / min for 5min to eliminate internal stress in the system. S7. Perform a pre-dispersion stability test on the wafer polishing slurry containing graphene nanosheets prepared in steps S1 to S6 to ensure that the delamination rate is ≤1% after standing for 72 hours.

[0015] Preferably, the performance testing in step S7 includes particle size distribution testing, zeta potential testing, and copper / cobalt corrosion rate testing.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention, through the introduction of graphene-modified abrasives and multi-component synergistic design, achieves a combination of high polishing efficiency, low corrosion rate, and excellent dispersion stability. Compared to traditional polishing slurries, the Cu / Co corrosion rate is reduced by more than 60%, the copper surface roughness Ra is ≤0.5nm, and there are no obvious micro-scratches on the polished wafer. The lubricating and mechanical abrasive properties of graphene nanosheets work synergistically to maintain a stable copper / cobalt removal rate ratio of 1:1±0.1, effectively avoiding dish-shaped pits and etching defects. The multi-stage ultrasonic dispersion and graded mixing process ensures abrasive dispersion uniformity ≥ The polishing slurry achieves a 99% yield, with a delamination rate ≤1% after 72 hours of standing, and batch-to-batch performance fluctuations ≤3%. The combined design of interface modifier and anti-agglomeration agent further enhances the wettability of the polishing slurry to the wafer surface and reduces polishing slurry residue. The defect repair agent, nano-hydroxyapatite, can actively fill nanoscale micro-defects on the wafer surface, significantly improving device reliability. In summary, the polishing slurry of this invention is suitable for 7nm / 5nm advanced process copper / cobalt interconnect CMP process, contains no harmful components, solves the problems of traditional polishing slurries, and meets the green requirements of semiconductor manufacturing. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] I. Materials: Unless otherwise specified, the components of the wafer polishing slurry containing graphene nanosheets in this invention are all commercially available. This invention proposes a wafer polishing slurry containing graphene nanosheets, which is composed of the following raw materials in parts by weight: abrasive matrix: 20-35 parts; graphene-modified abrasive: 5-12 parts; oxidant: 3-8 parts; complexing agent: 1.5-4 parts; metal corrosion inhibitor: 0.8-2.5 parts; pH adjuster: 0.5-1.8 parts; dispersant stabilizer: 0.3-1.2 parts; interface modifier: 0.2-0.9 parts; defect repair agent: 0.15-0.6 parts; corrosion inhibitor: 0.1-0.5 parts; wettability regulator: 0.08-0.3 parts; anti-agglomeration agent: 0.05-0.2 parts; deionized water: 30-45 parts.

[0019] It should be noted that the abrasive matrix is ​​composed of colloidal silica and nano-alumina, wherein the colloidal silica comprises 18-32 parts and the nano-alumina comprises 2-3 parts.

[0020] It should be noted that the graphene-modified abrasive is composed of silane coupling agent-modified graphene nanosheets and cerium oxide nanospheres, wherein the silane coupling agent-modified graphene nanosheets comprise 0.5-2 parts and the cerium oxide nanospheres comprise 4.5-10 parts. The silane coupling agent modified graphene nanosheets are modified with KH550 silane coupling agent, with a sheet thickness of 1-3 nm and a lateral dimension of 50-200 nm.

[0021] It should be noted that the oxidant is composed of hydrogen peroxide and ferric nitrate, with the hydrogen peroxide comprising 2-6 parts and the ferric nitrate comprising 1-2 parts.

[0022] It should be noted that the complexing agent is composed of aminotriacetic acid, citric acid and disodium ethylenediaminetetraacetate, wherein the aminotriacetic acid is 0.5-1.5 parts, the citric acid is 0.4-1 parts, and the disodium ethylenediaminetetraacetate is 0.6-1.5 parts.

[0023] It should be noted that the metal corrosion inhibitor is composed of benzotriazole, mercaptobenzothiazole and 2-mercaptobenzimidazole, wherein the benzotriazole content is 0.3-1 parts, the mercaptobenzothiazole content is 0.2-0.8 parts, and the 2-mercaptobenzimidazole content is 0.3-0.7 parts.

[0024] It should be noted that the pH adjuster is composed of potassium hydroxide and boric acid, wherein the potassium hydroxide content is 0.3-1.2 parts and the boric acid content is 0.2-0.6 parts. The dispersant stabilizer is ammonium polyacrylate with a molecular weight of 8000-15000; The interface modifier is a perfluorooctyl sulfonate ammonium type fluorocarbon surfactant, which is functionalized by grafting phosphate groups onto its hydrophilic end, and has a surface tension ≤25mN / m.

[0025] It should be noted that the defect repair agent is nano-hydroxyapatite with a particle size of 20-50nm. The corrosion inhibitor is sodium phytate; The wettability regulator is polyethylene glycol 400; The anti-agglomeration agent is composed of sodium dodecylbenzenesulfonate and polyoxyethylene ether, wherein the sodium dodecylbenzenesulfonate is 0.03-0.12 parts and the polyoxyethylene ether is 0.02-0.08 parts.

[0026] II. Process: Based on the above formulation, this invention also proposes a method for preparing a wafer polishing slurry containing graphene nanosheets, specifically including the following steps: S1. 18-32 parts of colloidal silica and 2-3 parts of nano-alumina in the abrasive matrix are passed through a 5μm airflow sieve to remove agglomerated particles. 0.5-2 parts of graphene nanosheets modified with silane coupling agent in the graphene-modified abrasive are added to 10-15 parts of deionized water. The mixture is ultrasonically dispersed for 30 minutes at 25±3℃ using a 300-500W ultrasonic disperser at a frequency of 40kHz. 4.5-10 parts of nano-cerium oxide microspheres are then added and ultrasonically dispersed for another 15 minutes. The dispersion uniformity is ≥99%. 2-6 parts of hydrogen peroxide and 1-2 parts of ferric nitrate should be stored at a constant temperature of 20±2℃ to prevent decomposition. S2. The ultrasonically dispersed graphene-modified abrasive suspension and abrasive matrix are put into a high-speed mixing kettle and mixed in three stages: coarse mixing: stirring at 500 r / min for 5 min to eliminate raw material accumulation; Fine mixing: Stir at 1200 r / min for 10 min, then add 0.5-1.5 parts of complexing agent aminotriacetic acid, 0.4-1 part of citric acid, and 0.6-1.5 parts of disodium ethylenediaminetetraacetate in sequence; Homogenization: Stir at 2000 r / min for 8 min, and monitor particle size distribution using an online laser particle size analyzer to ensure that the abrasive particle size variation coefficient is ≤5%; S3. Pump 0.3-1 parts of the metal corrosion inhibitor benzotriazole, 0.2-0.8 parts of mercaptobenzothiazole, 0.3-0.7 parts of 2-mercaptobenzimidazole and 5-8 parts of deionized water into a static mixer in a certain proportion, control the water temperature at 18-22℃, premix into a homogeneous solution, add 0.1-0.5 parts of the corrosion inhibitor sodium phytate, and inject in a pulsed manner at a pulse frequency of 10Hz to avoid excessive local concentration; S4. Add the mixture from step S2 and the premixed solution from step S3 into a mixing vessel and mix in two stages: First stage: Stir at 800 r / min for 4 min, add 0.3-1.2 parts of potassium hydroxide and 0.2-0.6 parts of boric acid to adjust the pH of the system to 8.5-9.5; Second stage: Stir at 1500 r / min for 6 min, then add 0.3-1.2 parts of ammonium polyacrylate dispersion stabilizer, 0.2-0.9 parts of ammonium perfluorooctyl sulfonate interface modifier, and 0.15-0.6 parts of nano-hydroxyapatite defect repair agent sequentially. The system viscosity is controlled to 5-8 using online viscosity feedback. Bye · s ; S5. Dissolve 0.08-0.3 parts of the wetting modifier polyethylene glycol 400, 0.03-0.12 parts of the anti-agglomeration agent sodium dodecylbenzenesulfonate, and 0.02-0.08 parts of polyoxyethylene ether in 15-22 parts of the remaining deionized water. Add the solution slowly dropwise to the mixing vessel at a rate of 5 mL / min. Reduce the stirring speed to 600 r / min and stir for 3 min. Then add the oxidant pretreated in step S1 and continue stirring for 2 min. S6. Filter the mixed polishing slurry through a 0.2μm precision filter and send it into an aging tank for constant aging at 25℃ for 24h. During this period, stir once every 6h at a speed of 300r / min for 5min to eliminate internal stress in the system.

[0027] Example 1: In this example, a wafer polishing slurry containing graphene nanosheets was prepared according to the following process. The formulation components are: abrasive matrix: 25 parts colloidal silicon dioxide and 2.5 parts nano alumina. Graphene-modified abrasive: 1.2 parts of graphene nanosheets modified with silane coupling agent and 7.3 parts of cerium oxide nanospheres; Oxidizing agent: 4 parts hydrogen peroxide, 1.5 parts ferric nitrate; Complexing agent: 1.0 part aminotriacetic acid, 0.7 part citric acid, 1.0 part disodium ethylenediaminetetraacetate; Metal corrosion inhibitors: 0.65 parts benzotriazole, 0.5 parts mercaptobenzothiazole, and 0.5 parts 2-mercaptobenzimidazole; pH adjuster: 0.75 parts potassium hydroxide, 0.4 parts boric acid; Dispersion stabilizer: 0.75 parts of ammonium polyacrylate (molecular weight 12000); Interface modifier: 0.55 parts of ammonium perfluorooctyl sulfonate; Defect repair agent: 0.35 parts of nano-hydroxyapatite; Corrosion inhibitor and synergist: 0.3 parts sodium phytate; Wetting agent: 4000.19 parts of polyethylene glycol; Anti-agglomeration agent: 0.075 parts sodium dodecylbenzenesulfonate, 0.05 parts polyoxyethylene ether; Deionized water: 37.5 parts.

[0028] Includes the following steps: S1: Raw material pretreatment and metering: Abrasive matrix: 25 parts colloidal silica and 2.5 parts nano alumina are sieved through an air classifier (5μm aperture) to remove agglomerated particles; Graphene-modified abrasive: 1.2 parts of silane coupling agent-modified graphene nanosheets were added to 12.5 parts of deionized water and ultrasonically dispersed at 25°C for 30 min using an ultrasonic disperser (power 400W) at a frequency of 40kHz. Then, 7.3 parts of nano-cerium oxide microspheres were added and ultrasonically dispersed for another 15 min, achieving a dispersion uniformity of 99.5%. Oxidizing agent: 4 parts hydrogen peroxide and 1.5 parts ferric nitrate, stored at a constant temperature of 20°C; S2: Preparation of premixed abrasive system: Coarse mixing: The ultrasonically dispersed graphene-modified abrasive suspension and abrasive matrix are put into a high-speed mixing vessel and stirred at 500 r / min for 5 min; Fine mixing: Stir at 1200 r / min for 10 min, then add 1.0 part of aminotriacetic acid, 0.7 part of citric acid, and 1.0 part of disodium ethylenediaminetetraacetate in sequence; Homogenization: Stirring at 2000 r / min for 8 min, the particle size variation coefficient was monitored by an online laser particle size analyzer and found to be 3.2%; S3: Corrosion inhibitor system compounding: 0.65 parts of benzotriazole, 0.5 parts of mercaptobenzothiazole, 0.5 parts of 2-mercaptobenzimidazole and 6.5 parts of deionized water are pumped into a static mixer at a water temperature of 20°C to premix into a homogeneous solution; 0.3 parts of sodium phytate were injected via pulse (pulse frequency 10Hz). S4: Mixed System Regulation: First stage: The mixture from step 2 and the premixed solution from step 3 are added to a mixing vessel and stirred at 800 rpm for 4 minutes. 0.75 parts of potassium hydroxide and 0.4 parts of boric acid are added, and the pH value is adjusted to 9.0. Second stage: Stir at 1500 rpm for 6 minutes, then add 0.75 parts of ammonium polyacrylate, 0.55 parts of ammonium perfluorooctyl sulfonate, and 0.35 parts of nano-hydroxyapatite sequentially. The system viscosity is controlled to 6.5 using online viscosity feedback. Bye · s ; S5: Wetting and anti-agglomeration system compounding: Dissolve 4000.19 parts of polyethylene glycol, 0.075 parts of sodium dodecylbenzenesulfonate, and 0.05 parts of polyoxyethylene ether in 18.5 parts of the remaining deionized water, add it to the mixing vessel at a dropping rate of 5 mL / min, reduce the speed to 600 r / min and stir for 3 min, add the oxidant pretreated in step 1, and continue stirring for 2 min; S6: Filtration and aging: The mixed polishing liquid is filtered through a 0.2μm precision filter and sent to an aging tank for constant temperature aging at 25℃ for 24 hours, with stirring at 300r / min for 5 minutes every 6 hours; Example 2: In this example, 18 parts colloidal silica, 2 parts nano-alumina; 0.5 parts silane coupling agent modified graphene nanosheets, 4.5 parts nano-cerium oxide microspheres; 2 parts hydrogen peroxide, 1 part ferric nitrate; 0.5 parts aminotriacetic acid, 0.4 parts citric acid, 0.6 parts disodium ethylenediaminetetraacetate; 0.3 parts benzotriazole, 0.2 parts mercaptobenzothiazole, 0.3 parts 2-mercaptobenzimidazole; 0.3 parts potassium hydroxide, 0.2 parts boric acid; 0.3 parts ammonium polyacrylate (molecular weight 8000); 0.2 parts perfluorooctyl sulfonate; 0.15 parts nano-hydroxyapatite; 0.1 parts sodium phytate; 0.08 parts polyethylene glycol 400; 0.03 parts sodium dodecylbenzenesulfonate, 0.02 parts polyoxyethylene ether; 30 parts deionized water. Other process parameters are the same as in Example 1.

[0029] Example 3: In this example, the following components were used: 32 parts colloidal silica, 3 parts nano-alumina; 2 parts silane coupling agent modified graphene nanosheets, 10 parts nano-cerium oxide microspheres; 6 parts hydrogen peroxide, 2 parts ferric nitrate; 1.5 parts aminotriacetic acid, 1 part citric acid, 1.5 parts disodium ethylenediaminetetraacetate; 1 part benzotriazole, 0.8 parts mercaptobenzothiazole, 0.7 parts 2-mercaptobenzimidazole; 1.2 parts potassium hydroxide, 0.6 parts boric acid; 1.2 parts ammonium polyacrylate (molecular weight 15000); 0.9 parts perfluorooctyl sulfonate; 0.6 parts nano-hydroxyapatite; 0.5 parts sodium phytate; 0.3 parts polyethylene glycol 400; 0.12 parts sodium dodecylbenzenesulfonate, 0.08 parts polyoxyethylene ether; 45 parts deionized water. Other process parameters were the same as in Example 1.

[0030] The material parameters of the wafer polishing slurry prepared in the examples are shown in Table 1: Table 1: Material parameters of the wafer polishing slurry prepared in the examples

[0031] Comparative Example 1: In this comparative example, there were 15 parts of graphene-modified abrasive, 2.5 parts of silane coupling agent-modified graphene nanosheets, and 12.5 parts of cerium oxide nanospheres. Other process parameters were the same as in Example 1.

[0032] Comparative Example 2: In this comparative example, the amount of colloidal silica was 15 parts, and other process parameters were the same as in Example 1.

[0033] Comparative Example 3: In this comparative example, benzotriazole was 1.5 parts, and other process parameters were the same as in Example 1.

[0034] The material parameters of the wafer polishing slurry prepared in the comparative example are shown in Table 2: Table 2: Material parameters of the wafer polishing slurry prepared in the comparative example

[0035] III. Performance Testing: The following performance tests were performed on the wafer polishing slurries prepared in the examples and comparative examples: a. Particle size distribution detection: Referring to GB / T19077-2016 "Particle size analysis by laser diffraction", a laser particle size analyzer (test range 0.01~10μm) was used to test the particle size of the polishing slurry abrasive, and the main peak particle size and coefficient of variation were recorded. Test conditions: The polishing slurry was diluted to an abrasive concentration of 0.5% (mass fraction), ultrasonically dispersed for 5 minutes, and then tested. Each sample was tested in parallel for 3 times and the average value was taken.

[0036] b. Zeta potential detection: Refer to GB / T29024.1-2021 "Particle size analysis - potentiometric analysis - Part 1: Electrophoresis", use a potentiometer to test and record the potential value; Test conditions: The polishing slurry was diluted to a solid content of 0.1% (mass fraction), the test temperature was 25℃, the dispersion medium was deionized water, and each sample was tested in parallel 3 times and the average value was taken.

[0037] c. Cu / Co corrosion rate detection: Refer to GB / T24196-2009 "Electrochemical test methods for corrosion of metals and alloys - Guidelines for potentiostatic and potentiodynamic polarization measurements" (equivalent to ASTM G59-14 (2020) "Standard test method for potentiodynamic polarization test"), and use an electrochemical workstation for testing; Test conditions: Three-electrode system (working electrode is 99.99% pure Cu / Co sheet with an area of ​​1 cm², reference electrode is saturated calomel electrode (SCE), auxiliary electrode is platinum sheet), test medium is the polishing solution to be tested, scan rate is 1 mV / s, test potential range is -0.2~0.8V (relative to open circuit potential), test time is 30 min, and the corrosion rate of Cu / Co (μm / min) is calculated by polarization curve.

[0038] d. Surface roughness inspection: Refer to SJ / T11631-2016 "Atomic force microscopy test method for surface roughness of silicon wafers" (complies with GB / T30598-2014 "General rules for measurement methods of atomic force microscopy"), and use atomic force microscopy to test the surface roughness Ra (nm) of the polished copper wafer. Test conditions: tapping mode, scanning range 5μm×5μm, scanning rate 1Hz, 5 different regions were selected for testing for each sample, and the average value was taken.

[0039] e. Dispersion stability test: Refer to SEMIC80-0712 "Stability Test Method of CMP Polishing Slurry" (Semiconductor Industry Standard), take 100mL of polishing slurry and place it in a stoppered transparent graduated cylinder, keep it at a constant temperature of 25℃ for 72h, and record the ratio of the volume of the supernatant to the total volume, which is the separation rate (%). Test conditions: graduated cylinder accuracy 0.1mL, avoid vibration during the standing process, and test each sample twice in parallel and take the average value.

[0040] Performance data for the examples and comparative examples are shown in Table 3: Table 3: Performance Data of Examples and Comparative Examples

[0041] IV. Analysis Conclusion: As shown in Tables 2 and 3, in Comparative Example 1, the excessive amount of graphene-modified abrasive led to severe abrasive agglomeration, with the main peak particle size increasing to 250 nm and the coefficient of variation reaching 12.5%. The Cu / Co corrosion rate nearly doubled, the surface roughness Ra increased to 1.2 nm, and the dispersion stability stratification rate reached 8.5%, resulting in polishing slurry failure. In Comparative Example 2, the insufficient colloidal silica resulted in insufficient mechanical grinding force of the abrasive matrix, a 50% increase in the Cu / Co corrosion rate, a surface roughness Ra reaching 0.85 nm, and a dispersion stability stratification rate of 5.2%. In Comparative Example 3, the excessive amount of benzotriazole, although reducing the corrosion rate, significantly decreased the polishing efficiency (Cu corrosion rate was only 0.04 μm / min), failing to meet the requirements of mass production processes. This verifies the scientific validity of the component range of the wafer polishing slurry examples of the present invention.

[0042] According to Tables 1 and 3, it can be seen that the proportions of each component in Example 1 of the present invention are balanced. 25 parts of colloidal silica and 2.5 parts of nano-alumina form a stable abrasive matrix. 1.2 parts of graphene-modified abrasive and 7.3 parts of nano-cerium oxide microspheres synergistically improve grinding efficiency and selectivity. The Cu / Co corrosion rate is close to 1:1, and the surface roughness Ra is as low as 0.45 nm. The complexing agent, corrosion inhibitor, and corrosion synergist are combined to effectively inhibit galvanic corrosion. The dispersant stabilizer and anti-agglomeration agent ensure uniform abrasive dispersion. The stratification rate is only 0.6%, and the overall performance is optimal. Therefore, Example 1 is the best embodiment of the present invention.

[0043] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A wafer polishing liquid containing graphene nanosheets, characterized by, It is composed of the following raw materials by weight: abrasive matrix: 20-35 parts; graphene modified abrasive: 5-12 parts; oxidizing agent: 3-8 parts; complexing agent: 1.5-4 parts; metal corrosion inhibitor: 0.8-2.5 parts; pH adjuster: 0.5-1.8 parts; dispersion stabilizer: 0.3-1.2 parts; interface modifier: 0.2-0.9 parts; defect repair agent: 0.15-0.6 parts; corrosion inhibitor synergist: 0.1-0.5 parts; wetting modifier: 0.08-0.3 parts; anti-agglomeration agent: 0.05-0.2 parts; deionized water: 30-45 parts.

2. The graphene nanoplatelet-containing wafer polishing solution according to claim 1, wherein The abrasive matrix is composed of colloidal silica and nano-alumina, the colloidal silica: 18-32 parts, the nano-alumina: 2-3 parts.

3. The graphene nanoplatelet-containing wafer polishing solution of claim 1, wherein the graphene nanoplatelet-containing wafer polishing solution is characterized by, The graphene modified abrasive is composed of silane coupling agent modified graphene nanosheet and nano cerium oxide microspheres, the silane coupling agent modified graphene nanosheet: 0.5-2 parts, the nano cerium oxide microspheres: 4.5-10 parts.

4. The graphene nanoplatelet-containing wafer polishing solution of claim 1, wherein the graphene nanoplatelet-containing wafer polishing solution is characterized by, The oxidizing agent is composed of hydrogen peroxide and ferric nitrate, the hydrogen peroxide: 2-6 parts, the ferric nitrate: 1-2 parts.

5. The graphene nanoplatelet-containing wafer polishing solution of claim 1, wherein the graphene nanoplatelet-containing wafer polishing solution is a liquid. The complexing agent is composed of amino triacetic acid, citric acid and ethylenediaminetetraacetic acid disodium, the amino triacetic acid: 0.5-1.5 parts, the citric acid: 0.4-1 part, the ethylenediaminetetraacetic acid disodium: 0.6-1.5 parts.

6. The graphene nanoplatelet-containing wafer polishing solution of claim 1, wherein, The metal corrosion inhibitor is composed of benzotriazole, mercaptobenzothiazole and 2-mercaptobenzimidazole, the benzotriazole: 0.3-1 part, the mercaptobenzothiazole: 0.2-0.8 part, the 2-mercaptobenzimidazole: 0.3-0.7 part.

7. The graphene nanoplatelet-containing wafer polishing solution of claim 1, wherein the graphene nanoplatelet-containing wafer polishing solution is a liquid. The pH adjuster is composed of potassium hydroxide and boric acid, the potassium hydroxide: 0.3-1.2 parts, the boric acid: 0.2-0.6 parts; the dispersion stabilizer is polyacrylic acid ammonium with a molecular weight of 8000-15000; the interface modifier is a perfluorooctyl sulfonic acid ammonium type fluorocarbon surfactant, which is functionalized and modified by grafting phosphate groups on the hydrophilic end.

8. The graphene nanoplatelet-containing wafer polishing solution of claim 1, wherein the graphene nanoplatelet-containing wafer polishing solution has a pH of 2 to 5. The defect repair agent is nano-hydroxyapatite with a particle size of 20-50 nm; the corrosion inhibitor synergist is sodium phytate; the wetting modifier is polyethylene glycol 400; the anti-agglomeration agent is composed of sodium dodecyl benzene sulfonate and polyoxyethylene ether, the sodium dodecyl benzene sulfonate: 0.03-0.12 parts, the polyoxyethylene ether: 0.02-0.08 parts. 9.The method of any one of claims 1-8, wherein the graphene nanoplatelet-containing wafer polishing solution is prepared by the following steps: (1) mixing the graphene nanoplatelets, the dispersing agent, and the solvent to obtain a mixture; (2) adding the surfactant into the mixture obtained in step (1) to obtain a graphene nanoplatelet-containing wafer polishing solution. It includes the following steps: S1. The abrasive matrix colloidal silica 18-32 parts and nano-alumina 2-3 parts are removed by airflow screen to remove agglomerated particles, the silane coupling agent modified graphene nanosheet 0.5-2 parts in the graphene modified abrasive is added to deionized water 10-15 parts, and the power 300-500 W ultrasonic disperser is used for ultrasonic dispersion at 25±3℃ for 30 min, the frequency is 40 kHz, the nano cerium oxide microspheres 4.5-10 parts are continuously ultrasonic dispersed for 15 min, and the dispersion uniformity is ≥99%; the oxidizing agent hydrogen peroxide 2-6 parts and ferric nitrate 1-2 parts are stored at 20±2℃ constant temperature to avoid decomposition; S2. Put the graphene modified abrasive suspension after ultrasonic dispersion, abrasive matrix into a high-speed mixing kettle, and mix in three stages: Coarse mixing: stirring at 500 r / min for 5 min to eliminate the accumulation of raw materials; Fine mixing: stirring at 1200 r / min for 10 min, and sequentially adding complexing agents such as amino triacetate 0.5-1.5 parts, citric acid 0.4-1 part, and ethylenediaminetetraacetic acid disodium 0.6-1.5 parts; Homogenization: stirring at 2000 r / min for 8 min, monitoring the particle size distribution through an online laser particle size analyzer, and ensuring that the coefficient of variation of the abrasive particle size is ≤5%; S3. Pump benzotriazole 0.3-1 part, mercaptobenzothiazole 0.2-0.8 part, 2-mercaptobenzimidazole 0.3-0.7 part, and deionized water 5-8 parts into a static mixer in proportion, control the water temperature at 18-22℃, and premix into a homogeneous solution. Add corrosion inhibitor synergist sodium phytate 0.1-0.5 part, and pulse injection at a pulse frequency of 10 Hz to avoid local high concentration; S4. Put the mixing system of step S2 and the premixed solution of step S3 into a mixing kettle, and mix in two stages: First stage: stirring at 800 r / min for 4 min, adding pH adjuster potassium hydroxide 0.3-1.2 parts and boric acid 0.2-0.6 parts to adjust the pH value of the system to 8.5-9.5; The second stage: stirring at 1500 r / min for 6 min, and then adding the dispersing stabilizer (0.3-1.2 parts of polyacrylamide), the interface modifier (0.2-0.9 parts of ammonium perfluorooctyl sulfonate), and the defect repairing agent (0.15-0.6 parts of nano-hydroxyapatite) in sequence, and the viscosity of the system is controlled to be 5-8 by online viscosity feedback Pa s ;​ S5. Dissolve the wetness adjuster polyethylene glycol 400 0.08-0.3 parts, the anti-agglomeration agent sodium dodecyl benzene sulfonate 0.03-0.12 parts, and the polyoxyethylene ether 0.02-0.08 parts in the remaining deionized water 15-22 parts, slowly drop into the mixing kettle, and reduce the stirring speed to 600 r / min for 3 min. Then add the pre-treated oxidizing agent in step S1, and continue stirring for 2 min; S6. Filter the mixed polishing liquid through a precision filter with a pore size of 0.2 μm, send it into an aging tank, and keep it at a constant temperature of 25℃ for 24 h. Stir every 6 h during the period at a speed of 300 r / min for 5 min to eliminate the stress in the system; S7. Perform pre-dispersion stability detection on the wafer polishing liquid containing graphene nanosheets prepared in steps S1 to S6, and ensure that the delamination rate is ≤1% after 72 h of standing.

10. The method of claim 9, wherein the graphene nanoplatelet-containing wafer polishing solution is prepared by adding 0.1 to 5 parts by weight of the graphene nanoplatelet-containing abrasive to 100 parts by weight of the base solution. The performance detection of step S7 includes particle size distribution detection, Zeta potential detection, and copper / cobalt corrosion rate detection.

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