A wafer grinding particle, its preparation method and application

Abstract

This invention discloses a wafer grinding particle, its preparation method, and its application. The preparation method includes: (1) mixing ultrapure water, alcohol, and organic base to prepare an alkaline solution with a pH of 8 or higher; mixing a silicon source with an acid to prepare an acidic hydrolysate, and mixing it with ultrapure water to prepare a pure water hydrolysate; (2) adding a silicon source to the alkaline solution and stirring to obtain initial particles, then adding a silane coupling agent and stirring to undergo a co-condensation reaction to obtain functional particles with aniline groups modified on their surface; (3) adding the acidic hydrolysate to the system and achieving particle growth through constant liquid level evaporation; then adding an organic base to adjust the pH to 9 or higher, adding the pure water hydrolysate, and achieving particle re-growth through constant liquid level evaporation to obtain peanut-shaped silica sol. The particles prepared by this method have the characteristics of simple preparation process, low metal ion content, good stability, and peanut-shaped structure, and can be used as grinding particles in the planarization process of semiconductor wafer manufacturing.

Description

Technical Field

[0001] This invention relates to the field of nanoscale silica material synthesis, and in particular to a wafer grinding particle, its preparation method, and its application. Background Technology

[0002] In wafer planarization processes, chemical mechanical polishing (CMP) using abrasive particles, polishing pads, and the wafer is essential to achieve ultra-smooth surfaces. Irregularly shaped nano-silica particles not only have extremely low metal impurity content (<1 PPM), significantly reducing the risk of short circuits caused by metal impurities during semiconductor material polishing, but their larger contact area with the polished material also greatly improves polishing efficiency, making them promising candidates for precision polishing in the microelectronics field.

[0003] CN112299425A describes a method for preparing a silica sol with a raised, serrated surface structure using organosilanes as the silicon source and alkoxyalkylamines (R1 OR2NH2) as the catalyst. While this structure provides a high surface roughness that can improve grinding efficiency, it also increases the risk of scratching precision devices during grinding. Furthermore, the alkoxyalkylamines used in this method are high-boiling-point organic compounds, which are difficult to remove during subsequent silica sol purification, thus affecting the sol's purity.

[0004] CN111470510A describes a process where a siloxane with a content of over 95% is mixed with acid or water to prepare an acidic composite solution. The shape of the solution is controlled by alternating batches of adding the acidic composite solution, ultimately yielding a cocoon-shaped or curved long-chain silica sol. However, this process requires multiple additions of the acidic composite solution and strict control over the acid value, the time interval between each addition, and the pH value, making the reaction process complex and unsuitable for scale-up production.

[0005] Therefore, it is evident that the existing wafer abrasive particles described above still have inconveniences and defects in terms of structure, method, and application, and urgently need further improvement. How to create a new type of wafer abrasive particle with a simple fabrication process, low metal ion content, good stability, and a peanut-shaped structure, and its fabrication method, has become a pressing goal for the industry. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a silicon sol wafer grinding particle and its preparation method, which makes the preparation process simple, has low metal ion content, good stability and peanut-shaped structure, thereby overcoming the shortcomings of the prior art.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a method for preparing wafer grinding particles, comprising the following steps:

[0009] (1) An alkaline solution with a pH of 8 or higher was prepared by mixing ultrapure water, alcohol and organic base; an acidic hydrolysate was prepared by mixing silicon source and acid; and a pure water hydrolysate was prepared by mixing silicon source and ultrapure water.

[0010] (2) Add silicon source to alkaline solution and stir to obtain initial particles, then add silane coupling agent and stir to react, so that silane coupling agent and initial particles undergo co-condensation reaction to obtain functional particles with aniline groups partially modified on the surface of silicon dioxide particles.

[0011] (3) Add acidic hydrolysate to the system of functional particles and achieve particle growth by evaporation at a constant liquid level for a period of time; then add organic base to adjust the pH to above 9, add pure water hydrolysate, and achieve particle re-growth through constant liquid level evaporation reaction to obtain wafer grinding particles in the form of peanut-shaped silica sol.

[0012] As a further improvement of the present invention, in step (3), a peristaltic pump is used to maintain the liquid level balance by adding acidic hydrolysate or pure water hydrolysate. The volume ratio of the amount of pure water hydrolysate added to the amount of acidic hydrolysate is 1.5-3. When it is less than 1.5 or greater than 3, the particles will be spherical due to insufficient growth or excessive growth. Preferably, the volume ratio of the amount of pure water hydrolysate added to the amount of acidic hydrolysate is 1.8-2.2.

[0013] Furthermore, in step (3), an organic base is added to adjust the pH so that the pH is maintained at 9.5-11. When the pH is below 9 or above 11, the functional groups on the silica particles are less functional, resulting in a lower proportion of peanut-shaped particles in the final synthesized sol.

[0014] Furthermore, in step (1), the alcohol is one or more of methanol, ethanol, and isopropanol.

[0015] In steps (1) and (3), the organic base is a metal-free alkaline substance, which is one or more of ammonia, tetramethylammonium hydroxide, and diethanolamine; more preferably, the organic base is ammonia.

[0016] In step (1), the acid mixed with the silicon source is an organic acid or an inorganic acid, and is one or more of dilute oxalic acid, dilute citric acid, dilute acetic acid, dilute lactic acid, and dilute hydrochloric acid; more preferably, the acid is an organic acid.

[0017] In steps (1) and (2), the silicon source is one or more of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate. More preferably, the silicon source is methyl orthosilicate.

[0018] In step (1), the volume ratio of ultrapure water to alcohol is (3-6):1; preferably, the volume ratio is (4-5):1.

[0019] In step (1), the pH of the alkaline solution is between 8 and 9 to ensure that the subsequent reaction between the silane coupling agent and the silicon source proceeds smoothly.

[0020] In step (1), the volume ratio of silicon source to acid is 1:(9-15); the volume ratio of silicon source to ultrapure water is 1:(9-15).

[0021] Furthermore, in step (2), after adding a silicon source to the alkaline solution, the silicon dioxide content is 5%-30%; preferably, the silicon dioxide content is 8%-15%.

[0022] In step (2), the initial particle reaction temperature is 25-35℃, the stirring speed is 400-1000r / min, and the reaction time is 1-3 hours; preferably, the initial particle reaction temperature is 30-35℃, the stirring speed is 500-800r / min, and the reaction time is 1.5-2 hours.

[0023] In step (2), the volume ratio of the amount of silane coupling agent added to the amount of silicon source is (1-4):25; when adding the silane coupling agent dropwise, the mixture is stirred rapidly while adding the agent dropwise, and the stirring speed is 1500-2000 r / min.

[0024] In step (2), the conditions for obtaining functional particles are: temperature of 45-65℃, stirring speed of 500-1000r / min, and reaction time of 5-8 hours; preferably, the conditions for obtaining functional particles are: temperature of 50-60℃, stirring speed of 700-900r / min, and reaction time of 6-7 hours.

[0025] In step (2), the silane coupling agent has the structure of an organic compound of Y-R1-Si(OR2)3, wherein Y is an aniline group, and R1 and R2 are hydrocarbon groups with 1-3 carbon atoms. Preferably, R1 = CH2 and R2 = CH3.

[0026] Furthermore, in step (3), acidic hydrolysate is added to the system of functional particles until the pH is 5-6.5, and the mixture is heated to boiling. The functional particles are grown by evaporation at a constant liquid level. During this process, acidic hydrolysate is added to maintain the liquid level balance.

[0027] An organic weak base is added to the system of functional particles until the pH of the system is above 9, and the pH of the system is maintained above 9. The particles are regrown through constant liquid level evaporation. Pure water hydrolysate is added during this process to maintain liquid level balance.

[0028] The wafer grinding particles prepared by the above method have a peanut-shaped silica sol form accounting for >60% of the particles, with a particle size of 40-120 nm; the content of all metal ions is <1 ppm, of which: Na ion content is <180 ppb, Al ion content is <35 ppb, Fe ion content is <12 ppb, Cu ion content is <2.5 ppb; silica sol viscosity is <9 mPa·s, pH is 7-10, and silica mass fraction is >20%.

[0029] On the other hand, the present invention also discloses wafer grinding particles prepared by the above-mentioned method.

[0030] In another aspect, the present invention also provides an application of the above-mentioned wafer abrasive particles as abrasive particles in the planarization process of semiconductor wafer manufacturing.

[0031] The reaction principle of this invention is as follows: A silane coupling agent undergoes a co-condensation reaction with the initial particles, modifying part of the surface of the silica particles with aniline groups. These aniline groups exhibit different hydrophilicity and hydrophobicity in different pH environments, allowing the silica particles to respond to pH changes. An acidic hydrolysate is added, and evaporation occurs at a constant liquid level, enabling the functional particles to grow through hydrolysis and polymerization. When the pH is adjusted above 9, the aniline groups become hydrophobic, inhibiting the subsequent hydrolysis and polymerization process of the functional particles, resulting in uneven growth of the silica particles, which then resemble peanuts.

[0032] By adopting the above technical solutions, the present invention has at least the following effects:

[0033] (1) The preparation process of the present invention is simple. The preparation method described above successfully prepared semiconductor wafer planarization grinding particles with peanut-shaped structure, wherein the proportion of peanut-shaped particles is >60%, the particle size is 40-120nm, and the stability is good.

[0034] (2) The content of all metal ions in the system is <1ppm, of which: Na ion content is <180ppb, Al ion content is <35ppb, Fe ion content is <12ppb, Cu ion content is <2.5ppb, and the metal ion content is low.

[0035] (3) The viscosity of the silica sol is <9mPa·s, the pH is 7-10, the mass fraction of silica is >20%, and the stability is good. Attached Figure Description

[0036] The above is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Figure 1 This is a scanning electron microscope image of silica sol in Embodiment 1 of the present invention.

[0038] Figure 2 This is a scanning electron microscope image of silica sol in Embodiment 2 of the present invention.

[0039] Figure 3 This is a scanning electron microscope image of silica sol in Embodiment 3 of the present invention.

[0040] Figure 4 This is a scanning electron microscope image of silica sol in Embodiment 4 of the present invention.

[0041] Figure 5 This is a scanning electron microscope image of silica sol in Embodiment 5 of the present invention.

[0042] Figure 6 This is a scanning electron microscope image of the silica sol in Comparative Example 1 of this invention.

[0043] Figure 7 This is a scanning electron microscope image of the silica sol in Comparative Example 2 of this invention.

[0044] Figure 8 This is a scanning electron microscope image of the silica sol in Comparative Example 3 of this invention.

[0045] Figure 9 This is a scanning electron microscope image of the silica sol in Comparative Example 4 of this invention.

[0046] in, Figures 1-8 The bottom right bar indicates 50nm. Figure 9 The scale in the lower left corner is 100nm. Detailed Implementation

[0047] Example 1

[0048] (1) An alkaline solution with pH = 8.6 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0049] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of dilute oxalic acid solution.

[0050] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0051] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0052] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 12 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0053] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0054] (7) Add 4.3 ml of ammonia water to adjust the pH to 9.8, heat to boiling, and achieve the regrowth of particles through constant liquid level evaporation reaction to obtain peanut-shaped silica sol, consuming 1500 ml of pure water hydrolysate.

[0055] Example 2 (replacing oxalic acid with citric acid)

[0056] (1) An alkaline solution with pH = 8.5 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0057] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of citric acid solution.

[0058] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0059] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0060] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 12 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0061] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0062] (7) Add 4.3 ml of ammonia water to adjust the pH to 9.9, heat to boiling, and achieve the regrowth of particles through constant liquid level evaporation reaction to obtain peanut-shaped silica sol, consuming 1500 ml of pure water hydrolysate.

[0063] Example 3 (Increasing the amount of silane coupling agent)

[0064] (1) An alkaline solution with pH = 8.8 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0065] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of dilute oxalic acid solution.

[0066] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0067] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0068] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 24 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0069] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0070] (7) Add 4.3 ml of ammonia water to adjust the pH to 9.8, heat to boiling, and achieve the regrowth of particles through constant liquid level evaporation reaction to obtain peanut-shaped silica sol, consuming 1500 ml of pure water hydrolysate.

[0071] Example 4 (with added ammonia dosage in step (7))

[0072] (1) An alkaline solution with pH = 8.6 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0073] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of dilute oxalic acid solution.

[0074] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0075] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0076] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 12 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0077] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0078] (7) Add 6.1 ml of ammonia water to adjust the pH to 10.6, heat to boiling, and achieve the regrowth of particles through constant liquid level evaporation reaction to obtain peanut-shaped silica sol, consuming 1500 ml of pure water hydrolysate.

[0079] Example 5 (Scale-up experiment of Example 1)

[0080] (1) Prepare an alkaline solution with pH=8.9 by mixing 9L of ultrapure water, 2L of ethanol and 40ml of ammonia.

[0081] (2) An acidic hydrolysate was prepared by mixing 1L of methyl orthosilicate with 10L of dilute oxalic acid solution.

[0082] (3) Prepare a pure water hydrolysate by mixing 2L of methyl orthosilicate with 25L of ultrapure water.

[0083] (4) Take 6L of alkaline solution, heat it to 32℃, add 1.6L of methyl orthosilicate, turn on the stirrer, set the speed to 650r / min, and react for 1.8 hours to obtain the initial particles.

[0084] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 120 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0085] (6) Add 2L of acidic hydrolysate to the functional particles, pH=5.7, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 8L of acidic hydrolysate.

[0086] (7) Add 43 ml of ammonia water to adjust the pH to 10.1, heat to boiling, and achieve the regrowth of particles through constant liquid level evaporation reaction to obtain peanut-shaped silica sol, consuming 15 L of pure water hydrolysate.

[0087] Comparative Example 1 (using pure water instead of silane coupling agent)

[0088] (1) An alkaline solution with pH = 8.6 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0089] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of dilute oxalic acid solution.

[0090] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0091] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0092] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 12 ml of ultrapure water, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0093] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0094] (7) Add 4.3 ml of ammonia water to adjust the pH to 9.8, heat to boiling, and achieve particle regrowth through constant liquid level evaporation reaction to obtain spherical silica sol, consuming 1500 ml of pure water hydrolysate.

[0095] Comparative Example 2 (reducing the amount of ammonia used in step (7))

[0096] (1) An alkaline solution with pH = 8.6 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0097] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of dilute oxalic acid solution.

[0098] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0099] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0100] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 12 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0101] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0102] (7) Add 2.8 ml of ammonia water to adjust the pH to 7.3, heat to boiling, and achieve particle regrowth through constant liquid level evaporation reaction. The proportion of peanut-shaped silica sol is low, and 1500 ml of pure water hydrolysate is consumed.

[0103] Comparative Example 3 (increasing the amount of pure water hydrolysate in step (7))

[0104] (1) An alkaline solution with pH = 8.6 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0105] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of dilute oxalic acid solution.

[0106] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0107] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0108] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 12 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0109] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0110] (7) Add 4.3 ml of ammonia water to adjust the pH to 9.8, heat to boiling, and achieve particle regrowth through constant liquid level evaporation reaction to obtain spherical silica sol, consuming 3500 ml of pure water hydrolysate.

[0111] Comparative Example 4 (increasing the amount of ammonia in step (7))

[0112] (1) An alkaline solution with pH = 8.6 was prepared by mixing 900 ml of ultrapure water, 200 ml of ethanol and 4 ml of ammonia.

[0113] (2) An acidic hydrolysate was prepared by mixing 100 mL of methyl orthosilicate with 1000 mL of dilute oxalic acid solution.

[0114] (3) Prepare a pure water hydrolysate by mixing 200 ml of methyl orthosilicate with 2500 ml of ultrapure water.

[0115] (4) Take 600 mL of alkaline solution, heat it to 32 °C, add 160 mL of methyl orthosilicate, turn on the stirrer and set the speed to 650 r / min. After reacting for 1.8 hours, the initial particles are obtained.

[0116] (5) Heat the initial particles to 50°C, turn on the stirrer at a speed of 1700 r / min, add 12 ml of aniline methyltrimethoxysilane, and then adjust the stirring speed to 800 r / min and continue the reaction for 6.5 hours to obtain functional particles.

[0117] (6) Add 200 ml of acidic hydrolysate (pH=5.7) to the functional particles, heat to boiling, and achieve functional particle growth by evaporation at a constant liquid level, consuming 800 ml of acidic hydrolysate.

[0118] (7) Add 10.8 ml of ammonia water to adjust the pH to 11.8, heat to boiling, and achieve particle re-growth through constant liquid level evaporation reaction. The proportion of peanut-shaped silica sol is low, and 1500 ml of pure water hydrolysate is consumed.

[0119] In Examples 1-5 above, after adding a silicon source to the alkaline solution, the silicon dioxide content is 5%-30%.

[0120] Figures 1-5 These are scanning electron microscope images of the silica sol obtained in Examples 1-5 of the present invention. Figure 1-5 It can be seen that peanut-shaped silica sol can be obtained, and the proportion of peanut-shaped particles is >60% and the particle size is 40-120nm; the content of all metal ions in the system is <1ppm, of which: Na ion content <180ppb, Al ion content <35ppb, Fe ion content <12ppb, Cu ion content <2.5ppb, and the metal ion content is low; (3) the silica sol viscosity is <9mPa·s, the pH is 7-10, and the silica mass fraction is >20%.

[0121] Figure 6 The image shown is a scanning electron microscope image of the silica sol in Comparative Example 1 of this invention. Since pure water was used instead of coupling agent in Comparative Example 1, functional particles modified with aniline groups could not be formed. As a result, only spherical silica sols could be generated, and peanut-shaped silica sols could not be generated.

[0122] Figure 7The image shown is a scanning electron microscope image of the silica sol in Comparative Example 2 of the present invention. Since the amount of ammonia water used in step (7) was reduced in Comparative Example 2, the pH value was less than 9. Therefore, the proportion of peanut-shaped silica sol obtained was relatively low.

[0123] Figure 8 The image shown is a scanning electron microscope image of the silica sol in Comparative Example 3 of this invention. Because Comparative Example 3 increased the amount of pure water hydrolysate in step (7), the volume ratio of the pure water hydrolysate to the acidic hydrolysate was greater than 3. Consequently, it could only generate spherical silica sol and could not generate peanut-shaped silica sol. Experiments confirmed that the situation was similar when the volume ratio was less than 1.5.

[0124] Figure 9 The image shown is a scanning electron microscope image of the silica sol in Comparative Example 4 of the present invention. Due to the excess ammonia in step (7) of Comparative Example 4, the pH value is greater than 11, and therefore the proportion of peanut-shaped silica sol obtained is also relatively low.

[0125] In Example 1 above, the alcohol can be replaced with methanol or isopropanol, or a combination of methanol, ethanol and isopropanol; the organic base can be replaced with tetramethylammonium hydroxide or diethanolamine, or a combination of ammonia, tetramethylammonium hydroxide and diethanolamine; the pH of the alkaline solution prepared by mixing can be set between 8 and 9, and the volume ratio of ultrapure water to alcohol can be replaced with 3:1 or 6:1.

[0126] In Example 1 above, the silicon source can be replaced with tetraethyl orthosilicate or propyl orthosilicate; or replaced with a combination of methyl orthosilicate, tetraethyl orthosilicate, and propyl orthosilicate; the acid that reacts with the silicon source can also be replaced with one or more of dilute acetic acid, dilute lactic acid, and dilute hydrochloric acid; the volume ratio of silicon source to acid can be replaced with 1:9 or 1:15; the volume ratio of silicon source to ultrapure water can be replaced with 1:9 or 1:15.

[0127] In Example 1 above, the reaction temperature for obtaining the initial particles can be replaced with 25°C, 30°C, or 35°C; the stirring speed can be replaced with 400 r / min, 500 r / min, 800 r / min, or 1000 r / min; and the reaction time can be replaced with 1 hour, 2 hours, or 3 hours.

[0128] In Example 1 above, the silane coupling agent can be replaced with one of the organic compounds with the structure Y-R1-Si(OR2)3, in addition to aniline methyltrimethoxysilane, where Y is an aniline group and R1 and R2 are hydrocarbon groups with 1-3 carbon atoms. The silane coupling agent is stirred during the reaction (the volume ratio of the added silane coupling agent to the silicon source can be replaced with 1:25 or 4:25; when adding the silane coupling agent dropwise, it is added dropwise while stirring rapidly, and the stirring speed can be replaced with 1500 r / min or 2000 r / min), so that the silane coupling agent and the initial particles undergo a co-condensation reaction to obtain functional particles with aniline groups partially modified on the surface of silica particles (in the reaction conditions for obtaining functional particles, the temperature can be replaced with 45℃, 60℃ or 65℃, the stirring speed is 500 r / min, 700 r / min or 900 r / min or 1000 r / min, and the reaction time can be replaced with 5 hours or 6 hours or 7 hours or 8 hours).

[0129] In Example 1 above, an acidic hydrolysate is added to the functional particle system, and particle growth is achieved through evaporation at a constant liquid level over a period of time (the acidic hydrolysate is added to the functional particle system until the pH can be replaced with 5 or 6.5, heated to boiling, and functional particle growth is achieved through evaporation at a constant liquid level; during this process, the acidic hydrolysate is added to maintain liquid level equilibrium). In Example 1 above, the volume ratio of the added pure water hydrolysate to the acidic hydrolysate can be replaced with 1.5 or 3.

[0130] The wafer abrasive particles of this invention functionalize initial silicon dioxide particles, causing them to grow in different pH systems, resulting in uneven particle growth and a peanut-shaped appearance. The wafer abrasive particles prepared by the above method of this invention have the advantages of simple preparation process, low metal ion content, and good stability, and can be used as abrasive particles in the planarization process of semiconductor wafer manufacturing.

[0131] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, or alterations made by those skilled in the art using the disclosed technical content shall fall within the protection scope of the present invention.

Claims

1. A method for preparing wafer grinding particles, characterized in that, Includes the following steps: (1) An alkaline solution with a pH of 8-9 was prepared by mixing ultrapure water, alcohol and organic base, with a volume ratio of ultrapure water to alcohol of (3-6):1; an acidic hydrolysate was prepared by mixing silicon source and acid, with a volume ratio of silicon source to acid of 1:(9-15); a pure water hydrolysate was prepared by mixing silicon source and ultrapure water, with a volume ratio of silicon source to ultrapure water of 1:(9-15). (2) Add silicon source to alkaline solution and stir to obtain initial particles, then add silane coupling agent and stir to cause silane coupling agent to undergo co-condensation reaction with initial particles to obtain functional particles with aniline groups modified on part of the surface of silica particles; the structure of silane coupling agent is one of the organic compounds of Y-R1-Si(OR2)3, wherein Y is aniline group, and R1 and R2 are hydrocarbon groups with 1-3 carbons; (3) Add acidic hydrolysate to the system of functional particles until the pH value is 5-6.5, and achieve particle growth by evaporation at a constant liquid level for a period of time; then add organic base to adjust the pH value so that the pH value is maintained at 9.5-11, add pure water hydrolysate, and the volume ratio of the amount of pure water hydrolysate to the amount of acidic hydrolysate is 1.5-3. The particles are regrown through constant liquid level evaporation reaction to obtain wafer grinding particles in the form of peanut-shaped silica sol.

2. The method for preparing wafer grinding particles according to claim 1, characterized in that, In step (1), the alcohol is one or more of methanol, ethanol and isopropanol; And / or, in steps (1) and (3), the organic base is one or more of ammonia, tetramethylammonium hydroxide, and diethanolamine; And / or, in step (1), the acid mixed with the silicon source is one or more of dilute oxalic acid, dilute citric acid, dilute acetic acid, dilute lactic acid, and dilute hydrochloric acid; And / or, in steps (1) and (2), the silicon source is one or more of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

3. The method for preparing wafer grinding particles according to claim 1, characterized in that, In step (2), after adding a silicon source to the alkaline solution, the silicon dioxide content is 5%-30%; And / or, in step (2), the reaction temperature for obtaining the initial particles is 25-35 ℃, the stirring speed is 400-1000 r / min, and the reaction time is 1-3 hours; And / or, in step (2), the volume ratio of the amount of silane coupling agent added to the amount of silicon source is (1-4):25; when adding the silane coupling agent dropwise, the mixture is stirred rapidly while adding the agent dropwise, and the stirring speed is 1500-2000 r / min. And / or, in step (2), the conditions for obtaining functional particles are: temperature of 45-65 ℃, stirring speed of 500-1000 r / min, and reaction time of 5-8 hours.

4. The method for preparing wafer grinding particles according to claim 3, characterized in that, In step (2), after adding a silicon source to the alkaline solution, the silicon dioxide content is 8%-15%; And / or, in step (2), the reaction temperature for obtaining the initial particles is 30-35 ℃, the stirring speed is 500-800 r / min, and the reaction time is 1.5-2 hours; And / or, in step (2), the conditions for obtaining functional particles are: temperature of 50-60℃, stirring speed of 700-900 r / min, and reaction time of 6-7 hours; And / or, in step (2), R1=CH2 and R2=CH3 in the silane coupling agent.

5. The method for preparing wafer grinding particles according to any one of claims 1-4, characterized in that, The wafer grinding particles prepared by the preparation method have a proportion of >60% in the form of peanut-shaped silica sol and a particle size of 40-120 nm. And / or, the content of all metal ions is <1 ppm, of which: Na ion content is <180 ppb, Al ion content is <35 ppb, Fe ion content is <12 ppb, and Cu ion content is <2.5 ppb; And / or, the silica sol viscosity is <9 mPa·s, the pH value is 7-10, and the silica mass fraction is >20%.

6. Wafer abrasive particles prepared by the method of any one of claims 1-5.

7. The application of the wafer abrasive particles according to claim 6 as abrasive particles in the planarization process of semiconductor wafer manufacturing.

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