Method for preparing cerium hydroxide dispersion and cerium hydroxide particle dispersion

Abstract

In the present invention, positively charged cerium hydroxide particles without undergoing surface charge treatment are subjected to ultrasonic agitation, so that a negatively charged polymer or monomer and the cerium hydroxide particles form a coordination bond, thereby forming a first surface coating layer and reversing the surface charge into a negative charge; and in a second coating step, a weakly positively charged polymer is added, so that by means of charge attraction, a polymeric ion pair is formed, thereby achieving a second charge reversal to a positive charge. Disclosed in the present invention is a method for multiple surface coatings of cerium hydroxide particles. The coated cerium hydroxide particles do not change the intrinsic electrical properties thereof, and can greatly reduce defects caused by mechanical forces during polishing, such as particle adhesion, thereby improving the product yield.

Description

Method for preparing cerium hydroxide dispersion liquid and cerium hydroxide particle dispersion liquid TECHNICAL FIELD

[0001] The present application relates to a method for preparing cerium hydroxide dispersion liquid and a chemical mechanical polishing liquid comprising the cerium hydroxide particle dispersion liquid. BACKGROUND

[0002] Cerium hydroxide abrasive particles are prepared by sol method, and the surface thereof is generally not subjected to charge treatment and is positively charged. When polishing is performed using the same, a large number of particles are generally adsorbed on the surface of a wafer. If, as in the case of sol-type cerium oxide particles, the thickness of the coating layer on the surface of cerium hydroxide particles is increased by using two different polymer molecules to achieve a polyion pair through charge attraction without changing the electrical properties of the particles themselves, the coating layer on the surface of the particles becomes a multilayered molecule containing different components (inorganic-organic composite material). Increasing the thickness of the coating layer on the surface of cerium hydroxide particles (hard shell and soft core) theoretically reduces the mechanical collision force of the particles on the surface of a wafer, which is like putting a thick multi-layered clothing on the surface of a metal ball to reduce defects such as particle adhesion due to mechanical force. However, the particle size of sol-type cerium hydroxide particles is only 15-20 nm, and the surface modification is relatively difficult due to the small particle size. There is no report on the multiple coating of the surface of cerium hydroxide particles. SUMMARY

[0003] To solve the above technical problems, the present application discloses a method for multiple coating of the surface of cerium hydroxide particles. The coated cerium hydroxide particles do not change the electrical properties of the particles themselves, and can greatly reduce defects such as particle adhesion due to mechanical force during polishing, thereby improving the yield of products. Specifically, the present application provides a method for preparing cerium hydroxide particles with twice reversed surface charge and its polishing application.

[0004] One aspect of the present application discloses a method for preparing a cerium hydroxide particle dispersion liquid, comprising:

[0005] S1: preparing a negative charge cerium hydroxide particle dispersion liquid: preparing a solution containing a multivalent phosphoric acid or carboxylate-based negatively charged polymer or monomer, adding an alkaline pH adjuster to adjust the pH, adding a cerium hydroxide particle dispersion liquid under stirring, stirring for at least T1, transferring the solution to an ultrasonic tank, and ultrasonicating until the particles are dispersed; obtaining a negative charge cerium hydroxide particle dispersion liquid R1;

[0006] S2: preparing a positive charge cerium hydroxide particle dispersion liquid: preparing a solution of a positively charged polymer, adding R1 under stirring, stirring for at least T2, transferring the solution to an ultrasonic tank, adding an acidic pH adjuster to adjust the pH after the solution is clarified, and continuing to ultrasonicate until the clarified liquid is maintained, obtaining a positive charge cerium hydroxide particle dispersion liquid R2.

[0007] Further, the negatively charged polymer or monomer containing polyphosphoric acid or carboxylate is polyphosphoric acid, phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, hydroxyethylidene diphosphonic acid, citric acid, diammonium hydrogen citrate, ammonium citrate.

[0008] Further, the positively charged polymer is a weakly positively charged polymer of primary or secondary amine-HCl.

[0009] Further, the positively charged polymer is PEI-HCl (Mw=10000), PAA-HCl-03 (Mw=3000), PAA-HCl-3L (Mw=15000), PAA-D19-HCl (Mw=40000), PAA-D11-HCl (Mw=100000).

[0010] Further, the concentration of the negatively charged polymer containing polyphosphoric acid or carboxylate in R1 is 0.05%-0.5%.

[0011] Further, the concentration of the positively charged polymer in R2 is 0.1-1.0%.

[0012] Further, the concentration of cerium hydroxide particles in R2 is 0.5-1.0%.

[0013] Further, in S1, the pH is adjusted to 7-9; in S2, the pH is adjusted to 2-6.

[0014] Further, in S1, T1=30-60 minutes; in S2, T2=30-60 minutes.

[0015] Further, in S1, the basic pH adjuster is selected from KOH, ammonia, imidazole.

[0016] Further, in S2, the acidic pH adjuster is selected from HNO3, acetic acid, picolinic acid.

[0017] Another aspect of the present application also discloses a cerium hydroxide polishing solution obtained by any of the above methods, characterized in that the solid content of cerium hydroxide in R2 is less than 2wt%.

[0018] The present application also discloses a method for using cerium hydroxide particle dispersion liquid, and the above-mentioned cerium hydroxide particle dispersion liquid is used for polishing silicon oxide.

[0019] The surface of the sol-type cerium hydroxide grinding particles is generally not charged and is positively charged. In order to reduce the mechanical collision force between the grinding particles and the polishing surface without changing the electrical properties of the particles themselves, the cerium hydroxide can be coated with two different molecules. This coating is achieved by secondary charge reversal. The present application is for cerium hydroxide whose surface is not charged and is positively charged. By means of ultrasonic oscillation, the negatively charged polymer or monomer and the cerium hydroxide particles form a coordination bond, the surface is coated with the first layer, the surface charge is reversed to negative charge. In the second coating, a weakly positively charged polymer is added, and through charge attraction, a polyion pair is formed to achieve secondary charge reversal and become positively charged.

[0020] After the above technical solution is adopted, compared with the prior art, the following beneficial effects are obtained: when the surface-treated cerium hydroxide is used for polishing, the defects caused by mechanical force during polishing, i.e. particle adhesion, are greatly reduced, thereby improving the yield of the product. DETAILED DESCRIPTION

[0021] The advantages of the present application are further described below in combination with specific embodiments.

[0022] Comparative sample A: 2% cerium hydroxide (particle size 20 nm measured by light scattering) is added to deionized water to dilute it to 1% dispersion, pH 4.5.

[0023] Comparative sample B1: 1.0 gram of 50% polyphosphoric acid is added to 499.0 grams of deionized water, and KOH is used to adjust the pH, then 500 grams of 2% cerium hydroxide (particle size 20 nm measured by light scattering) is added under stirring for at least 30 minutes, and the solution is transferred to a 20 kHz ultrasonic tank for ultrasonic until the particles are dispersed. Finally, the solution contains 1% cerium hydroxide, 0.05% polyphosphoric acid, and pH 8.5.

[0024] Comparative sample B2: 3.0 grams of 50% polyphosphoric acid is added to 497.0 grams of deionized water, and KOH is used to adjust, then 500 grams of 2% cerium hydroxide (particle size 20 nm measured by light scattering) is added under stirring for at least 30 minutes, and the solution is transferred to a 20 kHz ultrasonic tank for ultrasonic until the particles are dispersed. Finally, the solution contains 1% cerium hydroxide, 0.15% polyphosphoric acid, and pH 8.6.

[0025] Comparative Sample B3: 10.0 grams of 50% polyphosphoric acid was added to 490.0 grams of deionized water, adjusted with KOH, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic bath at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.5% polyphosphoric acid, pH 9.0.

[0026] Comparative Samples C1a-C1c: 0.5 grams of 99% phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate was added to 499.5 grams of deionized water, adjusted to pH with imidazole, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic bath at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.05% phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate, pH 7.4.

[0027] Comparative Samples C2a-C2c: 1.5 grams of 99% phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate was added to 498.5 grams of deionized water, adjusted to pH with imidazole, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic bath at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.15% phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate, pH 7.5.

[0028] Comparative Samples C3a-C3c: 5.0 grams of 99% phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate was added to 495.0 grams of deionized water, adjusted to pH with imidazole, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic bath at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.5% phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate, pH 8.0.

[0029] Comparative Sample D1: 0.5 grams of 98% hydroxyethylidene diphosphonic acid was added to 499.5 grams of deionized water, adjusted to pH with imidazole, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic bath at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.05% hydroxyethylidene diphosphonic acid, pH 8.1.

[0030] Comparative Sample D2: 3.0 grams of 98% hydroxyethylidene diphosphonic acid was added to 497.0 grams of deionized water, pH adjusted with imidazole, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic tank at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.3% hydroxyethylidene diphosphonic acid, pH 8.4.

[0031] Comparative Sample D3: 5.0 grams of 98% hydroxyethylidene diphosphonic acid was added to 495.0 grams of deionized water, pH adjusted with imidazole, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic tank at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.5% hydroxyethylidene diphosphonic acid, pH 8.6.

[0032] Comparative Sample Ela-E1c: 0.5 grams of 99% citric acid / diammonium hydrogen citrate / ammonium citrate was added to 499.5 grams of deionized water, pH adjusted with ammonia, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic tank at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.05% citric acid / diammonium hydrogen citrate / ammonium citrate, pH 7.0.

[0033] Comparative Sample E2a-E2c: 2.0 grams of 99% citric acid / diammonium hydrogen citrate / ammonium citrate was added to 498.0 grams of deionized water, pH adjusted with ammonia, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic tank at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.2% citric acid / diammonium hydrogen citrate / ammonium citrate, pH 7.3.

[0034] Comparative Sample E3a-E3c: 5.0 grams of 99% citric acid / diammonium hydrogen citrate / ammonium citrate was added to 495.0 grams of deionized water, pH adjusted with ammonia, then 500 grams of 2% cerium hydroxide (particle size 20 nm by light scattering) was added with stirring for at least 30 minutes, the solution was transferred to an ultrasonic tank at 20 kHz and sonicated until the particles were dispersed. Finally, the solution contained 1% cerium hydroxide, 0.5% citric acid / diammonium hydrogen citrate / ammonium citrate, pH 7.9.

[0035] Zeta potentials and particle sizes of cerium hydroxide particles before and after surface treatment are listed in Table I.

[0036] Comparative Sample A is the surface charge (zeta = +45 mV) and particle size (size = 20 nm) of cerium hydroxide particles as they exist stably prior to surface treatment. When polyphosphoric acid (polymeric phosphoric acid, Comparative Sample B) is added, the zeta potential becomes less than -30 mV and the particles do not noticeably grow over three weeks; likewise, when phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate / ethylidene diphosphonic acid (monomeric polyphosphoric acid, Comparative Samples C, D) is added, the zeta potential and particle size are also stable. When citric acid / diammonium hydrogen citrate / ammonium citrate (monomeric polycarboxylic acid, Comparative Sample E) is added, the zeta potential is less than -30 mV and the particles also do not noticeably grow over three weeks.

[0037] Polyphosphoric acid, phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate, ethylidene diphosphonic acid, and citric acid / diammonium hydrogen citrate / ammonium citrate all enable a first charge reversal of the surface of cerium hydroxide particles and maintain sol stability. We prefer Comparative Samples E2b (containing polycarboxylate) and B2 (containing polyphosphate) for a second charge reversal.

[0038] Inventive Sample Al: 1.0 gram of 99% PEI-HCl is added to 499.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b is added with stirring for at least 30 minutes, transferred to an ultrasonic tank at 20 kHz, and the pH is adjusted with acetic acid after the colloid is clear. The dispersion is sonicated until the clear liquid is maintained. Finally, the sample contains 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.1% PEI-HCl, and pH 2.0. The particles are stable, with a zeta potential of +40 mV.

[0039] Inventive Sample A2: 2.0 grams of 99% PEI-HCl is added to 498.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b is added with stirring for at least 30 minutes, transferred to an ultrasonic tank at 20 kHz, and the pH is adjusted with acetic acid after the colloid is clear. The dispersion is sonicated until the clear liquid is maintained. Finally, the sample contains 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.2% PEI-HCl, and pH 3.4. The particles are stable, with a zeta potential of +42 mV.

[0040] Invention Sample A3: 10.0 grams of 99% PEI-HCl was added to 490.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with acetic acid after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 1.0% PEI-HCl, pH 4.0. The particles were stable, with a zeta potential of +43 mV.

[0041] Invention Sample B1a: 2.5 grams of 40% PAA-HCl-03 was added to 497.5 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.1% PAA-HCl-03, pH 3.0. The particles were stable, with a zeta potential of +42 mV.

[0042] Invention Sample B1b: 5.0 grams of 40% PAA-HCl-03 was added to 495.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.2% PAA-HCl-03, pH 4.2. The particles were stable, with a zeta potential of +38 mV.

[0043] Invention Sample B1c: 25.0 grams of 40% PAA-HCl-03 was added to 475.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 1.0% PAA-HCl-03, pH 5.0. The particles were stable, with a zeta potential of +35 mV.

[0044] Invention Sample B2a: 2.0 grams of 50% PAA-HCl-3L was added to 498.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.1% PAA-HCl-3L, pH 3.0. The particles were stable, and the zeta potential was +45 mV.

[0045] Invention Sample B2b: 4.0 grams of 50% PAA-HCl-3L was added to 496.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.2% PAA-HCl-3L, pH 4.2. The particles were stable, and the zeta potential was +48 mV.

[0046] Invention Sample B2c: 20.0 grams of 50% PAA-HCl-3L was added to 480.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 1.0% PAA-HCl-3L, pH 5.0. The particles were stable, and the zeta potential was +48 mV.

[0047] Invention Sample C1a: 5.0 grams of 21% PAA-D19-HCl was added to 495.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.1% PAA-D19-HCl, pH 4.0. The particles were stable, and the zeta potential was +40 mV.

[0048] Invention Sample C1 b: 9.5 grams of 21% PAA-D19-HCl was added to 490.5 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.2% PAA-D19-HCl, pH 5.3. The particles were stable, and the zeta potential was +48 mV.

[0049] Invention Sample C1 c: 50.0 grams of 21% PAA-D19-HCl was added to 450.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 1.0% PAA-D19-HCl, pH 6.0. The particles were stable, and the zeta potential was +44 mV.

[0050] Invention Sample C2a: 2.5 grams of 40% PAA-D11-HCl was added to 497.5 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.1% PAA-D11-HCl, pH 4.0. The particles were stable, and the zeta potential was +48 mV.

[0051] Invention Sample C2b: 5.0 grams of 40% PAA-D11-HCl was added to 495.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic bath at 20 kHz, and the pH was adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 0.2% PAA-D11-HCl, pH 5.3. The particles were stable, and the zeta potential was +50 mV.

[0052] Invention Sample C2c: 25.0 grams of 40% PAA-D11-HCl was added to 475.0 grams of deionized water, then 500.0 grams of Comparative Sample E2b was added with stirring for at least 30 minutes, transferred to an ultrasonic tank at 20 kHz, and the pH adjusted with HNO3 after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% diammonium hydrogen citrate, 1.0% PAA-D11-HCl, pH 6.0. The particles were stable, and the zeta potential was +45 mV.

[0053] Invention Sample Dl: 2.5 grams of 40% PAA-HCl-03 was added to 497.5 grams of deionized water, then 500.0 grams of Comparative Sample B2 was added with stirring for at least 30 minutes, transferred to an ultrasonic tank at 20 kHz, and the pH adjusted with picolinic acid after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% polyphosphoric acid, 0.1% PAA-HCl-03, pH 4.0. The particles were stable, and the zeta potential was +40 mV.

[0054] Invention Sample D2: 5.0 grams of 40% PAA-HCl-03 was added to 495.0 grams of deionized water, then 500.0 grams of Comparative Sample B2 was added with stirring for at least 30 minutes, transferred to an ultrasonic tank at 20 kHz, and the pH adjusted with picolinic acid after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% polyphosphoric acid, 0.2% PAA-HCl-03, pH 5.1. The particles were stable, and the zeta potential was +44 mV.

[0055] Invention Sample D3: 25.0 grams of 40% PAA-HCl-03 was added to 475.0 grams of deionized water, then 500.0 grams of Comparative Sample B2 was added with stirring for at least 30 minutes, transferred to an ultrasonic tank at 20 kHz, and the pH adjusted with picolinic acid after the colloid was clear, and the dispersion was continued until the clear solution was maintained. Finally, the sample contained 0.5% cerium hydroxide, 0.1% polyphosphoric acid, 1.0% PAA-HCl-03, pH 6.0. The particles were stable, and the zeta potential was +47 mV.

[0056] The zeta potential and particle size of cerium hydroxide particles before and after surface treatment are listed in Table 1.

[0057] Table 1 Zeta Potential and Particle Size

[0058] All the content percentage in the present application is mass percentage content.

[0059] From the above examples, we can see that the first coating on the surface of cerium hydroxide particles can use a polymer or monomer containing a multi-phosphoric acid or carboxylate negative charged group, and the specific embodiments are polyphosphoric acid, phosphoric acid / ammonium dihydrogen phosphate / diammonium hydrogen phosphate, hydroxyethylidene diphosphonic acid, and citric acid / diammonium hydrogen citrate / ammonium citrate, etc., to realize the charge reversal to negative charge. The second coating is to use a polymer containing a primary or secondary amine-HCl type weakly positively charged group, such as PEI-HCl, PAA-HCl-03, PAA-HCl-3L, PAA-D19-HCl, and PAA-D11-HCl, etc., to realize the second charge reversal, which is positively charged.

[0060] Polishing object: TEOS blank wafer

[0061] Polishing instrument: Mirra polishing machine; IC1000 polishing pad; NanoSpec film thickness measurement system (NanoSpec6100-300, Shanghai Nanospec Technology Corporation); white light interferometer.

[0062] Polishing conditions: the rotation speeds of Platten and Carrier are 93 rpm and 87 rpm respectively, the polishing pressure is 4.0 psi, and the polishing liquid flow rate is 150 mL / min.

[0063] Polishing step: using the above prepared polishing liquid, the above polishing instrument and polishing conditions are used to polish the TEOS blank wafer. After polishing, the white light interferometer is used to detect the adhesion of the TEOS blank wafer surface, and the results are shown in Table 2.

[0064] Table 2 Surface adhesion of TEOS blank wafer before and after polishing

[0065] As can be seen from Table 2, using cerium hydroxide bare particles (comparative sample A) to polish the TEOS blank wafer, the surface will produce serious particle adhesion. But once the surface of cerium hydroxide is coated (inventive samples A, B, C and D), the particle adhesion on the surface of the TEOS blank wafer will be greatly reduced without changing its electrical properties. The reason is that by two times of coating, the thickness of the surface of cerium hydroxide particles is increased, which is like wearing multiple layers of thick clothes on the surface of a metal ball, so that the coated cerium hydroxide particles do not directly contact each other, and at the same time, the coated polymer cerium hydroxide particles become polymer macromolecules, and the attraction between them is weakened, thereby effectively reducing the particle adhesion.

[0066] In summary, using the negatively charged polymer or monomer and the weakly positively charged polymer defined in the present application can effectively achieve the secondary reverse of the cerium hydroxide particles, the coated cerium hydroxide particles do not change the electrical properties of the particles themselves, and by increasing the thickness of the surface coating layer of the cerium hydroxide particles (hard shell and soft core), the defects of particle adhesion caused by mechanical force on the wafer surface during polishing can be reduced, thereby greatly improving the yield of the product.

[0067] It should be noted that the embodiments of the present application have better implementation, and do not limit the present application in any form, any skilled person in the art can change or modify the above disclosed technical content into equivalent effective embodiments, as long as it does not deviate from the technical solution of the present application, any modification or equivalent change and modification of the above embodiments according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A method for producing a cerium hydroxide particle dispersion liquid, characterized by, The application relates to a method for preparing a cerium hydroxide particle dispersion liquid, and a method for using the cerium hydroxide particle dispersion liquid. S1: preparing a negative charge cerium hydroxide particle dispersion liquid: configuring a solution containing a polybasic phosphoric acid or carboxylate negative charge polymer or monomer, adding an alkaline pH regulator to adjust the pH, adding the cerium hydroxide particle dispersion liquid under stirring, stirring for at least T1, transferring the solution to an ultrasonic tank, and ultrasonically dispersing until the particles are dispersed; a negative charge cerium hydroxide particle dispersion liquid R1 is obtained; S2: preparing a positive charge cerium hydroxide particle dispersion liquid: configuring a solution containing a positive charge polymer, adding R1 under stirring, stirring for at least T2, transferring the solution to an ultrasonic tank, adding an acidic pH regulator to adjust the pH after the solution is clarified, and continuously ultrasonically dispersing until the clarified liquid is maintained, and a positive charge cerium hydroxide particle dispersion liquid R2 is obtained.

2. The cerium hydroxide particle dispersion liquid according to claim 1, wherein The polybasic phosphoric acid or carboxylate negative charge polymer or monomer is polyphosphoric acid, phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, hydroxyethylidene diphosphonic acid, citric acid, diammonium hydrogen citrate, ammonium citrate.

3. The cerium hydroxide particle dispersion liquid according to claim 1, wherein The positive charge polymer is a weakly positive charge polymer of primary or secondary amine-HCl.

4. The cerium hydroxide particle dispersion liquid according to claim 3, wherein The positive charge polymer is PEI-HCl, PAA-HCl-03, PAA-HCl-3L, PAA-D19-HCl, PAA-D11-HCl.

5. The cerium hydroxide particle dispersion liquid according to claim 1, wherein The mass percentage concentration of the polybasic phosphoric acid or carboxylate negative charge polymer in R1 is 0.05% to 0.5%.

6. The cerium hydroxide particle dispersion liquid according to claim 1, wherein The mass percentage concentration of the positive charge polymer in R2 is 0.1% to 1.0%.

7. The cerium hydroxide particle dispersion liquid according to claim 1, wherein The concentration of the cerium hydroxide particles in R2 is 0.5% to 1.0%.

8. The cerium hydroxide particle dispersion liquid according to claim 1, wherein In S1, the pH is adjusted to 7 to 9.

9. The cerium hydroxide particle dispersion liquid according to claim 1, wherein In S2, the pH is adjusted to 2 to 6.

10. The cerium hydroxide particle dispersion liquid according to claim 1, wherein In S1, T1 is 30 to 60 minutes; and in S2, T2 is 30 to 60 minutes.

11. The cerium hydroxide particle dispersion liquid according to claim 1, wherein In S1, the alkaline pH regulator is selected from KOH, ammonia water and imidazole.

12. The cerium hydroxide particle dispersion liquid according to claim 1, wherein In S2, the acidic pH regulator is selected from HNO3, acetic acid and picolinic acid.

13. The cerium hydroxide particle dispersion liquid according to claim 1, wherein The particle size of the cerium hydroxide particles in R1 is 20 to 60 nm.

14. The cerium hydroxide particle dispersion liquid according to claim 1, wherein The particle size of the cerium hydroxide particles in R2 is 50 to 130 nm.

15. A cerium hydroxide polishing solution obtained from the method of any preceding claim, characterized in that, The solid content of the cerium hydroxide in R2 is less than 2 wt%.

16. A method for using a cerium hydroxide particle dispersion liquid, wherein the cerium hydroxide particle dispersion liquid as claimed in any one of claims 1 to 15 is used for polishing silicon oxide.

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