Silicon wafer cleaning solution as well as preparation method and application thereof

Abstract

The invention relates to the technical field of semiconductor cleaning, in particular to silicon wafer cleaning liquid as well as a preparation method and application thereof. The silicon wafer cleaning solution is prepared from the following raw materials in parts by mass: 150 to 200 parts of dicyandiamide quaternary ammonium salt, 15 to 25 parts of nano-hydroxyapatite, 8 to 12 parts of ionic liquid, 3 to 7 parts of organic alkali, 40 to 60 parts of surfactant, 30 to 50 parts of oxidant, 2 to 4 parts of corrosion inhibitor, 5 to 8 parts of chelating agent and 400 to 600 parts of water. The cleaning solution has excellent low-temperature stability, can realize high-precision cleaning with low metal ion residue and low surface roughness in a wide temperature range of-10 DEG C to 40 DEG C, and can solve the long-standing problem of precision, cost and environmental protection collaborative optimization in the field of semiconductor cleaning.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor cleaning, and in particular to a silicon wafer cleaning liquid, a preparation method thereof, and an application thereof. Background Art

[0002] The cleaning of silicon wafers in the prior art has the following defects: 1. Defects of alkaline cleaning system 1) Uncontrollable etching: The etching rate of traditional strong alkali fluctuates greatly (±0.05nm / min); 2) Metal redeposition: The metal ions produced by etching are easily re-adsorbed on the silicon wafer surface; 3) Low-temperature failure: The fluidity of conventional solvents decreases significantly below 5°C.

[0003] 2. Process efficiency limitations 1) High energy consumption cost: cleaning needs to maintain a high temperature of 45-60℃; 2) Difficulty in waste liquid treatment: fluoride cleaning system produces highly polluted wastewater; 3) High material loss: the cleaning liquid life is only 24-48 hours.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] An object of the present invention is to provide a silicon wafer cleaning liquid having excellent low-temperature stability, capable of cleaning silicon wafers with high precision and high efficiency while reducing the roughness of the surface thereof, and having a long service life of the cleaning liquid.

[0006] Another object of the present invention is to provide a method for preparing a silicon wafer cleaning solution, which is simple and easy to implement. The obtained silicon wafer cleaning solution has excellent low-temperature stability, good cleaning ability for silicon wafers, can control the etching rate, and extend its service life.

[0007] Another object of the present invention is to provide a method for cleaning silicon wafers, which can efficiently clean silicon wafers and achieve a high recovery rate of nano-hydroxyapatite and ionic liquid.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted: A silicon wafer cleaning solution is prepared from the following raw materials in parts by weight: 150-200 parts of dicyandiamide quaternary ammonium salt, 15-25 parts of nano-hydroxyapatite, 8-12 parts of ionic liquid, 3-7 parts of organic base, 40-60 parts of surfactant, 30-50 parts of oxidant, 2-4 parts of corrosion inhibitor, 5-8 parts of chelating agent and 400-600 parts of water.

[0009] In some embodiments, the silicon wafer cleaning solution is prepared from raw materials comprising the following parts by weight: 160-180 parts of dicyandiamide quaternary ammonium salt, 17-22 parts of nano-hydroxyapatite, 9-11 parts of ionic liquid, 4-6 parts of organic base, 45-55 parts of surfactant, 35-45 parts of oxidant, 2.5-3.5 parts of corrosion inhibitor, 6-7 parts of chelating agent and 180-550 parts of water.

[0010] In some embodiments, the dicyandiamide quaternary ammonium salt includes at least one of dicyandiamide dodecyltrimethylammonium chloride and dicyandiamide octyldimethylammonium bromide.

[0011] In some embodiments, the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium chloride.

[0012] In some embodiments, the particle size of the nano-hydroxyapatite is 50-100 μm.

[0013] In some embodiments, the surfactant includes polyethylene glycol octylphenyl ether.

[0014] In some embodiments, the oxidizing agent comprises ammonium persulfate.

[0015] In some embodiments, the corrosion inhibitor includes 1,2,3-benzotriazole.

[0016] In some embodiments, the chelating agent comprises disodium EDTA.

[0017] In some embodiments, the organic base comprises tetramethylammonium hydroxide.

[0018] The method for preparing the silicon wafer cleaning solution as described above comprises the following steps: (a) Obtain a dispersion of nanohydroxyapatite, water, and a portion of the ionic liquid.

[0019] (b) performing a first mixing of the dispersion, the dicyandiamide quaternary ammonium salt, the corrosion inhibitor, and the remaining portion of the ionic liquid to obtain a first system.

[0020] (c) Under ozone conditions, the first system is mixed with an oxidant and an organic base solution to obtain a second system.

[0021] (d) performing a second mixing of the second system with a surfactant and a chelating agent solution to obtain a silicon wafer cleaning solution.

[0022] In some embodiments, the dispersion is subjected to a heating treatment during the obtaining process, and the heating temperature is 45-60°C.

[0023] In some embodiments, the specific preparation method of the dispersion includes: performing a first ultrasonic dispersion on the nano-hydroxyapatite and the water under heating conditions, and then adding the portion of the ionic liquid to perform a second ultrasonic dispersion.

[0024] In some embodiments, during the preparation of the dispersion, the first ultrasonic dispersion time is 20-35 min, the first ultrasonic dispersion power is 700-850 W, and the first ultrasonic dispersion power is 30-50 kHz; the second ultrasonic dispersion time is 10-20 min.

[0025] In some embodiments, the mass content of the partial ionic liquid in the total ionic liquid is 35% to 45%.

[0026] In some embodiments, the first mixing speed is 4000-6000 rpm, and the first mixing time is 10-30 min.

[0027] In some embodiments, the first mixing is performed in a reactor at a temperature of 25-40°C.

[0028] In some embodiments, the mass concentration of the oxidant in the oxidant and organic base solution is 25% to 35%.

[0029] In some embodiments, the ozone flow rate is 2-6 L / min, and the ozone introduction time is 10-20 min.

[0030] In some embodiments, the second mixing speed is 100-300 rpm, and the second mixing time is 20-40 min.

[0031] In some embodiments, during the preparation of the silicon wafer cleaning solution, the materials are mixed using a microfluidic mixing method.

[0032] In some embodiments, the microfluidic mixing uses a Y-shaped glass chip with a channel width of 180-550 μm, a depth of 45-350 μm, and a tortuous channel length of 4-6 cm.

[0033] In some embodiments, in step (a), the flow rate of the dispersion of nanohydroxyapatite and water is controlled to be 0.3-0.6 mL / min, and the flow rate of the partial ionic liquid is controlled to be 1-1.5 mL / min.

[0034] A method for cleaning a silicon wafer comprises the following steps: The silicon wafer is pre-cleaned, mainly cleaned, rinsed and dried; the main cleaning adopts the cleaning agent or the silicon wafer cleaning liquid obtained by the preparation method of the silicon wafer cleaning liquid.

[0035] In some embodiments, the main cleaning temperature is 43-47°C; the main cleaning soaking time is 8-15 minutes; the main cleaning is megasonic assisted; the ratio of the cleaning agent to the silicon wafer is (4.5-5.5) L:1m 2 .

[0036] In some embodiments, the method further includes: recycling the waste cleaning liquid after injection and cleaning; the recycling process adopts a ceramic membrane recovery system; the membrane pore size of the ceramic membrane recovery system is 45~55nm, the porosity is 40%~50%; the transmembrane pressure difference is 0.3~0.8MPa, the cross flow velocity is 2~4m / s, and the temperature is 38~45℃.

[0037] In some embodiments, the recovered mixed liquid is subjected to vacuum distillation regeneration to recover the ionic liquid and nano-hydroxyapatite; the vacuum distillation regeneration temperature is 50~85°C, the vacuum degree of the vacuum distillation regeneration is 8~12Pa, and the scraping speed is 150~250rpm.

[0038] Compared with the prior art, the present invention has the following beneficial effects: (1) The silicon wafer cleaning solution of the present invention is prepared from dicyandiamide-based quaternary ammonium salt, nano-hydroxyapatite, ionic liquid, organic base, surfactant, oxidant, corrosion inhibitor, chelating agent and water. The cleaning solution can improve the metal ion removal rate, uniformity and roughness. The oxidation-chelation cascade reaction (metal oxidation → coordination dissolution) makes the Fe / Cu removal rate reach more than 99.8%. The ionic liquid / surfactant compound makes the contact angle difference less than 2°, achieving submicron level wetting uniformity. The hydroxyapatite particle size and corrosion inhibitor work together to keep the Ra value in the range of 0.2-0.5nm. Through the four-fold mechanism of "chemical oxidation-physical scrubbing-chelation stabilization-surface protection", atomic-level surface integrity control is achieved while ensuring cleaning efficiency. The cleaning solution of the present invention achieves high-precision cleaning with low metal ion residue and low surface roughness in a wide temperature range of -10℃ to 40℃. It can solve the long-standing problem of coordinated optimization of precision, cost and environmental protection in the field of semiconductor cleaning.

[0039] (2) The preparation method of the silicon wafer cleaning solution of the present invention is that the nano-hydroxyapatite can adsorb ionic liquid, that is, the cation of the imidazole ionic liquid is combined with the negative charge on the surface of the hydroxyapatite through Coulomb force to form a core-shell structure; the hydrophobic chain of the dicyandiamide quaternary ammonium salt and the benzene ring of the corrosion inhibitor produce π-alkyl interactions to form composite micelles, and O3 2+ / Cu + Oxidized to Fe 3 + / Cu 2+(Oxidation potential increased from 0.77V to 2.07V), promoting the subsequent chelation of the chelating agent, the carboxylic acid group of the chelating agent and the PO4 on the surface of hydroxyapatite 3- Competitive adsorption of metal ions forms a more stable [Fe(EDTA)]⁻ complex. Ozone controls the oxidation rate of the hydrophobic chains of the quaternary ammonium salt, preventing excessive hydrophilization and micelle disintegration. Organic base maintains a pH of 10.5-11.5, ensuring the chelating capacity of the chelating agent (pKa = 10.3) while preventing hydroxyapatite dissolution. Through the coordinated use of these steps, this method improves the etching rate control accuracy to ±0.02nm / min, extends the cleaning solution life to 120h, and achieves a 92% recyclability rate for the nanohydroxyapatite.

[0040] (3) The silicon wafer cleaning method of the present invention uses the above-mentioned silicon wafer cleaning liquid, which can improve the cleaning accuracy and efficiency, control the etching uniformity and silicon surface roughness, and can be carried out at a lower temperature; through ceramic membrane recovery and vacuum distillation technology, a 92% recycling rate of nano-hydroxyapatite is achieved, zero fluoride is used, waste liquid discharge is reduced by 68.75%, and the unit consumption cost is reduced to 0.75 yuan / wafer. DETAILED DESCRIPTION

[0041] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0042] According to one aspect of the present invention, the present invention relates to a silicon wafer cleaning solution prepared from raw materials including the following parts by mass: 150-200 parts of dicyandiamide quaternary ammonium salt, 15-25 parts of nano-hydroxyapatite, 8-12 parts of ionic liquid, 3-7 parts of organic base, 40-60 parts of surfactant, 30-50 parts of oxidant, 2-4 parts of corrosion inhibitor, 5-8 parts of chelating agent and 400-600 parts of water.

[0043] The silicon wafer cleaning solution of the present invention is prepared from a dicyandiamide-based quaternary ammonium salt, nano-hydroxyapatite, an ionic liquid, an organic base, a surfactant, an oxidant, a corrosion inhibitor, a chelating agent, and water. This cleaning solution improves metal ion removal rate, uniformity, and surface roughness. An oxidation-chelation cascade reaction (metal oxidation → coordinated dissolution) achieves an Fe / Cu removal rate exceeding 99.8%. The ionic liquid / surfactant combination achieves a contact angle difference of less than 2°, achieving submicron-level wetting uniformity. The hydroxyapatite particle size and the corrosion inhibitor synergize to maintain an Ra value within the range of 0.2-0.5 nm. Through a four-pronged mechanism of "chemical oxidation-physical scrubbing-chelation stabilization-surface protection," the solution achieves atomic-level surface integrity control while maintaining cleaning efficiency. This cleaning solution achieves high-precision cleaning with low metal ion residue and low surface roughness over a wide temperature range of -10°C to 40°C. It addresses the long-standing challenge of optimizing precision, cost, and environmental performance in the semiconductor cleaning industry.

[0044] The cleaning solution of this invention uses a dicyandiamide-based quaternary ammonium salt instead of a traditional strong base. Combined with the selective adsorption of nanohydroxyapatite and the low-temperature stability of ionic liquids, this solution improves control precision by addressing the issues of large etching rate fluctuation (±0.05nm / min), high metal ion residue (15-20ppb), and low-temperature failure associated with traditional strong bases. It achieves atomic-level cleaning with metal residue ≤3ppb, etching uniformity ±1.0%, and surface roughness Ra ≤0.15nm over a wide temperature range (-10°C to 40°C). Furthermore, it optimizes process efficiency by overcoming the limitations of existing processes, such as high temperature dependence (45-60°C), short cleaning solution life (24-48h), and high material loss. This solution improves etching rate control precision to ±0.02nm / min, extends the cleaning solution life to 120h, and achieves a 92% recycling rate for the nanohydroxyapatite. Regarding environmental upgrades: Solve the problems of fluoride pollution and high COD waste liquid, achieve zero fluoride use, reduce waste liquid emissions by 68.75%, and reduce unit consumption costs to 50% of the industry benchmark (0.75 yuan / piece).

[0045] In some embodiments, the dicyandiamide quaternary ammonium salt comprises 150 to 200 parts, for example, 150, 160, 170, 180, 190, 200, etc. The dicyandiamide quaternary ammonium salt in an appropriate proportion absorbs negatively charged contaminants on the silicon wafer surface through its cationic properties, disrupting the binding of metal ions to the substrate. The long-chain alkyl group (C12) enhances the ability to remove hydrophobic contaminants, the short-chain group (C8) improves solution permeability, and the dicyandiamide group provides coordination sites to assist the chelating agent.

[0046] In some embodiments, the nano-hydroxyapatite is 15 to 25 parts, for example, 15 parts, 16 parts, 17 parts, 18 parts, 20 parts, and 25 parts. The nano-hydroxyapatite in an appropriate proportion removes surface particle contaminants by nano-scale physical friction, and the hydroxyl groups selectively adsorb Ca2+ / Fe 3+ Metal ions such as quaternary ammonium salts form a dual effect of "chemical adsorption-physical scrubbing", and the surface microporous structure loads corrosion inhibitors to achieve local slow release.

[0047] In some embodiments, the ionic liquid is present in an amount of 8 to 12 parts, for example, 8 parts, 9 parts, 10 parts, 11 parts, or 12 parts. A suitable proportion of the ionic liquid can improve the dispersion stability of the organic base and the surfactant, the imidazole ring forms a π-π interaction with the metal ion, and the tetrafluoroborate ion promotes the activation of the oxidant.

[0048] In some embodiments, the organic base is present in an amount of 3 to 7 parts, for example, 3 parts, 4 parts, 5 parts, 6 parts, or 7 parts. A suitable proportion of the organic base can maintain an alkaline environment of pH 10-12, dissolve the silicon surface oxide layer (SiO2 + OH⁻ → SiO3²⁻), form a micellar structure with the quaternary ammonium salt, and enhance the solubilization of organic pollutants.

[0049] In some embodiments, the surfactant is present in an amount of 40 to 60 parts, for example, 40 parts, 45 parts, 50 parts, 55 parts, or 60 parts. A suitable ratio of surfactant can reduce the surface tension to <30 mN / m, promote the spreading and penetration of the cleaning solution in the nanoscale slots, form mixed micelles with the quaternary ammonium salt, and enhance the encapsulation ability of the nanoparticles.

[0050] In some embodiments, the oxidant is 30 to 50 parts, such as 30 parts, 35 parts, 40 parts, 45 parts or 50 parts. A suitable proportion of the oxidant can generate sulfate radicals (SO4· - ) oxidizes and decomposes organic matter, converting low-valent metal ions (such as Fe 2+ ) is oxidized to a high valence state (Fe 3+ ) facilitates chelation and forms an oxidation-corrosion equilibrium with TMAH under alkaline conditions to avoid excessive etching.

[0051] In some embodiments, the corrosion inhibitor is present in an amount of 2 to 4 parts, for example, 2 parts, 3 parts, or 4 parts. A suitable ratio of the corrosion inhibitor can form a [N-Si] coordination bond protective film on the silicon surface with a corrosion inhibition efficiency of >95%. The inhibitor preferentially adsorbs on lattice defects and synergistically repairs surface micro-damage with hydroxyapatite.

[0052] In some embodiments, the chelating agent is 5 to 8 parts, such as 5 parts, 5.5 parts, 6 parts, 7 parts, 7.5 parts, 8 parts, etc. Suitable chelating agents chelate Cu through the tetracarboxylic acid groups. 2+ / Fe 3+ Plasma, stability constant up to 10 16 -10 25 ; Form an oxidation-chelation series reaction with the oxidant to prevent the redeposition of metal ions.

[0053] In some embodiments, the amount of water is 400 to 600 parts, such as 400 parts, 450 parts, 500 parts, 550 parts, or 600 parts.

[0054] In some embodiments, the silicon wafer cleaning solution is prepared from the following raw materials in parts by weight: 160-180 parts of dicyandiamide quaternary ammonium salt, 17-22 parts of nanohydroxyapatite, 9-11 parts of ionic liquid, 4-6 parts of organic base, 45-55 parts of surfactant, 35-45 parts of oxidant, 2.5-3.5 parts of corrosion inhibitor, 6-7 parts of chelating agent and 180-550 parts of water.

[0055] The present invention is more conducive to ensuring the cleaning effect of the cleaning liquid by further optimizing the ratio of dicyandiamide quaternary ammonium salt, nano hydroxyapatite, ionic liquid, organic base, surfactant, oxidant, corrosion inhibitor, chelating agent and water.

[0056] In some embodiments, the dicyandiamide quaternary ammonium salt includes at least one of dicyandiamide dodecyltrimethylammonium chloride (DCDA-C12) and dicyandiamide octyldimethylammonium bromide (DCDA-C8). In some embodiments, the mass ratio of dicyandiamide dodecyltrimethylammonium chloride to dicyandiamide octyldimethylammonium bromide is (1.5-3):1.

[0057] In some embodiments, the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium chloride. In some embodiments, the mass ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate to 1-butyl-3-methylimidazolium chloride is 1:(1-3).

[0058] In some embodiments, the particle size of the nano-hydroxyapatite is 50-100 μm, for example, 50 μm, 60 μm, 80 μm, 100 μm, etc.

[0059] In some embodiments, the surfactant includes polyethylene glycol octylphenyl ether.

[0060] In some embodiments, the organic base includes tetramethylammonium hydroxide (TMAH).

[0061] In some embodiments, the oxidizing agent comprises ammonium persulfate.

[0062] In some embodiments, the corrosion inhibitor includes 1,2,3-benzotriazole (BTA).

[0063] In some embodiments, the chelating agent includes disodium ethylenediaminetetraacetate (EDTA-2Na).

[0064] According to another aspect of the present invention, the present invention also relates to a method for preparing the silicon wafer cleaning solution as described above, comprising the following steps: (a) Obtain a dispersion of nanohydroxyapatite, water, and a portion of the ionic liquid.

[0065] (b) The dispersion, the dicyandiamide quaternary ammonium salt, the corrosion inhibitor, and the remaining portion of the ionic liquid are first mixed to obtain a first system.

[0066] (c) Under ozone conditions, the first system is mixed with an oxidant and an organic base solution to obtain a second system.

[0067] (d) The second system is mixed with a surfactant and a chelating agent solution to obtain a silicon wafer cleaning solution.

[0068] The preparation method of the silicon wafer cleaning liquid of the present invention comprises the following steps: nano-hydroxyapatite can adsorb ionic liquid, that is, cations of imidazole ionic liquid bind to negative charges on the surface of hydroxyapatite through Coulomb force to form a core-shell structure; hydrophobic chains of dicyandiamide quaternary ammonium salt interact with benzene rings of corrosion inhibitor to form composite micelles. , O3 converts Fe 2+ / Cu + Oxidized to Fe 3+ / Cu 2+ (Oxidation potential increased from 0.77V to 2.07V), promoting the subsequent chelation of the chelating agent, the carboxylic acid group of the chelating agent and the PO4 on the surface of hydroxyapatite 3- Competitive adsorption of metal ions to form a more stable [Fe(EDTA)]⁻ complex; ozone can control the oxidation rate of the hydrophobic chain of the quaternary ammonium salt to avoid excessive hydrophilization leading to micelle disintegration; organic bases can maintain the pH at 10.5-11.5, which not only ensures the chelating ability of the chelating agent (pKa=10.3) but also prevents the dissolution of hydroxyapatite.

[0069] In some embodiments, in the core-shell structure, transmission electron microscopy shows that the shell thickness is 2-3 nm.

[0070] In some embodiments, the dispersion is subjected to a heat treatment during acquisition, and the temperature of the heat treatment is 45-60°C. The heat treatment can promote the dissociation of -OH groups on the surface of hydroxyapatite, and the Zeta potential drops from -15mV to -25mV (pH 7), thereby providing active sites for the subsequent adsorption of ionic liquids.

[0071] In some embodiments, the specific preparation method of the dispersion includes: performing a first ultrasonic dispersion on the nanohydroxyapatite and the water under heating conditions, and then adding the partial ionic liquid for a second ultrasonic dispersion; the time of the first ultrasonic dispersion is 20~35min (20min, 30min or 35min, etc.), the first ultrasonic dispersion power is 700~850W (750W, 780W, 800W or 850W, etc.), and the power of the first ultrasonic dispersion is 30~50kHz (30kHz, 35kHz, 40kHz or 50kHz, etc.); the time of the second ultrasonic dispersion is 10~20min (10min, 12min, 15min or 20min, etc.).

[0072] In some embodiments, the mass content of the partial ionic liquid in the total ionic liquid is 35% to 45%, for example, 35%, 40% or 45%.

[0073] In some embodiments, the first mixing speed is 4000-6000 rpm, for example, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, or 6000 rpm. The first mixing time is 10-30 min, for example, 10 min, 20 min, or 30 min. The present invention adopts appropriate first mixing conditions to ensure that the materials are fully mixed and reacted to obtain a composite micelle system.

[0074] In some embodiments, the first mixing is performed in a reactor, and the temperature of the first mixing is 25-40°C, for example, 25°C, 30°C, 35°C, 40°C, etc.

[0075] In some embodiments, in the oxidant and organic base solution, the mass concentration of the oxidant is 25% to 35%, such as 25%, 30% or 35%.

[0076] In some embodiments, the ozone flow rate is 2 to 6 L / min (e.g., 2 L / min, 3 L / min, 5 L / min, 6 L / min, etc.), and the ozone injection time is 10 to 20 minutes, such as 10 minutes, 15 minutes, or 20 minutes. By using an appropriate ozone flow rate and injection time, the oxidation rate of the quaternary ammonium salt hydrophobic chain can be better controlled at 15% to 20%, thereby avoiding excessive hydrophilization that may lead to micelle disintegration.

[0077] In some embodiments, the second mixing speed is 100-300 rpm, for example, 100 rpm, 200 rpm, 300 rpm, etc.; the second mixing time is 20-40 min, for example, 20 min, 30 min, or 40 min, etc. Quality control is performed through appropriate second mixing. The zeta potential is detected to be -20-25 mV, and the surface tension is detected to be 26-30 mN / m.

[0078] In some embodiments, during the preparation of the silicon wafer cleaning solution of the present invention, microfluidics is used to mix the various materials. In some embodiments, the dispersion is obtained by microfluidic mixing, and the microfluidic mixing uses a Y-shaped glass chip with a channel width of 180 to 550 μm (e.g., 450 μm, 500 μm, 550 μm, etc.), a depth of 45 to 350 μm (250 μm, 300 μm, 350 μm, etc.), and a tortuous channel length of 4 to 6 cm (4 cm, 5 cm, or 6 cm, etc.); the flow rate of the nanohydroxyapatite and water is controlled to be 0.3 to 0.6 mL / min (e.g., 0.3 mL / min, 0.5 mL / min, or 0.6 mL / min, etc.), and the flow rate of the partial ionic liquid is controlled to be 1 to 1.5 mL / min (e.g., 1 mL / min, 1.2 mL / min, 1.5 mL / min, etc.). Mixing efficiency: Reynolds number Re=80, achieving laminar shear mixing, dispersion uniformity>95%; output: a nanocomposite dispersion with surface-coated ionic liquid (particle size distribution PDI<0.15) is obtained.

[0079] In some embodiments, in step (a), the dicyandiamide quaternary ammonium salt solution and the remaining ionic liquid use a Y-shaped glass chip (channel width of 500 μm, depth of 300 μm, and tortuous channel length of 5 cm) with operating parameters: dicyandiamide quaternary ammonium salt solution: ionic liquid = 1:3 (volume ratio), Reynolds number Re = 200 (laminar mixing); mixing time: 15 s, mixing uniformity (CV) ≤ 5% (determined by fluorescent probe method).

[0080] This invention utilizes microfluidic mixing to achieve atomic-level etching control through a combination of "precise component distribution and dynamic reaction regulation." The specific mechanisms include: 1) Using Y-shaped microchannels and laminar shear, the molar ratio of dicyandiamide-based quaternary ammonium salt, corrosion inhibitor, and oxidant fluctuates by less than 0.5%, eliminating concentration gradient-induced etching rate deviations at the source. 2) By injecting oxidant and ozone gases in stages through a microfluidic chip, the SO₄⁻ radical generation rate is stabilized at 0.1-0.15 mmol / (L·s), avoiding the pulsating radical concentration fluctuations (±30%) seen in traditional batch mixing. This reduces the standard deviation of the etching rate from ±0.1 nm / min to ±0.02 nm / min (verified by SEM linewidth analysis). 3) Inhibitor molecules preferentially adsorb to active sites on the silicon wafer surface via electroosmotic flow (zeta potential -25 mV) within the microchannel, forming a dense protective film with a thickness of 1.2±0.3 nm (as measured by AFM), suppressing lateral overetching. 3) Microfluidic technology achieves long-term performance maintenance through “component stability enhancement-side reaction inhibition”. Nanomaterial anti-agglomeration: Hydroxyapatite particles in microfluidic shear field (shear rate 10 4 s - ¹) is uniformly coated with an ionic liquid shell (2-3 nm thick, as confirmed by TEM), reducing interparticle van der Waals forces by 68% and achieving particle size growth of less than 5% within 120 hours (DLS data), thus preventing adsorption degradation due to agglomeration. Free radical lifetime regulation: Spatiotemporally isolated injection of ozone and ammonium persulfate within the microchannel extends the free radical half-life from 8 hours in a conventional stirred tank to 35 hours (electron spin resonance detection), and improves oxidation capacity retention from 40% to 85%. pH gradient buffering: The microfluidic system integrates an online pH sensor (accuracy ±0.05), enabling real-time adjustment of the organic base injection rate, narrowing the pH fluctuation range of the cleaning solution from 10.5-12.0 to 11.2±0.1. This inhibits the dissolution of hydroxyapatite (reducing solubility from 5 mg / L to 0.3 mg / L) and the hydrolysis of quaternary ammonium salts.

[0081] According to another aspect of the present invention, the present invention also relates to a method for cleaning a silicon wafer, comprising the following steps: The silicon wafer is pre-cleaned, mainly cleaned, rinsed and dried. The main cleaning adopts the cleaning agent or the silicon wafer cleaning solution obtained by the preparation method of the silicon wafer cleaning solution.

[0082] The silicon wafer cleaning method of the present invention adopts the above-mentioned silicon wafer cleaning liquid, which can improve the cleaning accuracy and efficiency, control the etching uniformity and silicon surface roughness, and can perform cleaning at a lower temperature.

[0083] In some embodiments, pre-cleaning is performed using ultrapure water (18-18.5 MΩ·cm) and ultrasonic treatment (35-45 kHz) for 3-6 minutes to initially remove surface impurities from the silicon wafer.

[0084] In some embodiments, the main cleaning temperature is 43-47°C; the main cleaning soaking time is 8-15 minutes; the main cleaning is assisted by megasonics: 0.8-1.2 MHz, with a power density of 1.5-3 W / cm². The ratio of the cleaning agent to the silicon wafer is (4.5-5.5) L:1m 2 ; In some embodiments, rinsing adopts three-stage rinsing, and the flow rate of pure water is (8~12L / min).

[0085] In some embodiments, Marangoni drying (pressure 10 -3 Pa).

[0086] Some embodiments also include recycling the waste cleaning fluid after injection and rinsing; this recycling process utilizes a ceramic membrane recovery system (pH adjusted to 6.5-7.0 to prevent dissolution of the nanoparticles). The ceramic membrane recovery (solid-liquid separation) equipment includes a tubular ceramic membrane assembly (made of Al2O3). The membrane pore size of the ceramic membrane recovery system is 45-55 nm (designed for hydroxyapatite), with a porosity of 40%-50%. The transmembrane pressure is 0.3-0.8 MPa, the cross-flow velocity is 2-4 m / s (to minimize concentration polarization), and the temperature is 38-45°C (to prevent organic polymerization).

[0087] Recovery efficiency: ionic liquid recovery rate ≥95%, solid impurity retention rate ≥99% (impurity particle size >100 nm).

[0088] The nanoparticle retention rate of the waste cleaning liquid after injection cleaning is >99.8%; the COD removal rate of the permeate is 85% (including quaternary ammonium salt decomposition products).

[0089] In some embodiments, the recovered mixed liquid undergoes vacuum distillation regeneration (solvent removal and activation) to recover the ionic liquid and nanohydroxyapatite. The equipment employed is a short-path molecular distillation apparatus. The vacuum distillation regeneration temperature is 50-85°C (well below the ionic liquid's decomposition temperature of 200°C), the vacuum level is 8-12 Pa (to prevent oxidation of the nanoparticles), and the distillation time is 50-70 minutes. The scraping speed is 150-250 rpm (to form a 0.1 mm refreshed liquid film). The regeneration process includes: (a) removal of adsorbed organic matter (TOC reduced from 5000 ppm to <50 ppm); (b) dissociation of the ionic liquid from the nanoparticles (recovery of [BMIM]Cl via evaporation-condensation); and (c) regeneration of hydroxyl groups on the hydroxyapatite surface (-OH peak intensity restored to 95% as measured by FTIR). Material recovery: The regenerated nanohydroxyapatite re-enters the microfluidic premixing system; the recovered ionic liquid is tested for purity (≥99% by HPLC) and then added to the silicon wafer cleaning solution formulation.

[0090] In some embodiments, the reagent circulation rate: the recovery rate of the dicyandiamide quaternary ammonium salt is ≥90%, and the purity of the ionic liquid is ≥99% (GC-MS detection of impurities <0.1%).

[0091] In some embodiments, etching uniformity: the extreme difference in etching depth on a 300mm silicon wafer surface is reduced from 1.8nm to 0.4nm (90-point measurement). In some embodiments, life test: after 120 hours of cyclic use, Fe 3+ The removal rate only dropped from 99.8% to 99.5%, and the surface tension was maintained at 28±1 mN / m. In some embodiments, cost analysis shows that microfluidic mixing increases raw material utilization to 98%, reducing waste costs by 42% compared to traditional processes.

[0092] The following is further explained with reference to specific embodiments and comparative examples.

[0093] Example 1 A silicon wafer cleaning solution is prepared from the following raw materials in parts by weight: 170 parts of dicyandiamide quaternary ammonium salt, 20 parts of nano-hydroxyapatite, 10 parts of ionic liquid, 5 parts of organic base, 50 parts of surfactant, 40 parts of oxidant, 3 parts of corrosion inhibitor, 6.5 parts of chelating agent and 500 parts of water. The dicyandiamide quaternary ammonium salt is dicyandiamide dodecyltrimethylammonium chloride, the ionic liquid is [BMIM]Cl, the surfactant is polyethylene glycol octylphenyl ether, the oxidant is ammonium persulfate, the corrosion inhibitor is EDTA-2Na, and the organic base is tetramethylammonium hydroxide.

[0094] The method for preparing a silicon wafer cleaning solution comprises the following steps: (a) Dispersion premixing: Nanohydroxyapatite (80 nm) was added to 50°C deionized water and ultrasonically dispersed for 30 min (800 W, 40 kHz) to obtain a nanohydroxyapatite dispersion. This dispersion was then proportionally introduced into a microfluidic chip with a portion of the ionic liquid (40% by mass of the total ionic liquid). Parameters: Channel structure: Y-shaped staggered microchannel (width 200 μm, depth 50 μm); Flow rate control: 0.5 mL / min for the nanoparticle phase and 1.2 mL / min for the ionic liquid phase; Mixing efficiency: Reynolds number Re = 80, achieving laminar shear mixing and dispersion uniformity > 95%; a nanocomposite dispersion coated with ionic liquid (particle size distribution PDI < 0.15) was obtained.

[0095] (b) Main reaction stage: Dicyandiamide quaternary ammonium salt, corrosion inhibitor and dispersion were added to a high-speed shear reactor (25°C) in sequence, and shear mixed at 5000 rpm for 20 min to form a composite micelle system.

[0096] (c) Oxidation activation stage: ozone (5 L / min) was introduced and an oxidant and an organic base solution were added. The mass content of the oxidant was 30%, and the reaction was carried out for 15 min.

[0097] (d) Final mixing stage: Add chelating agent solution (2 mol / L) and surfactant, and stir at a low speed of 200 rpm for 30 min.

[0098] Example 2 A silicon wafer cleaning solution is prepared from the following raw materials in parts by weight: 160 parts of dicyandiamide quaternary ammonium salt, 22 parts of nano-hydroxyapatite, 9 parts of ionic liquid, 6 parts of organic base, 45 parts of surfactant, 35 parts of oxidant, 2.5 parts of corrosion inhibitor, 7 parts of chelating agent and 450 parts of water.

[0099] The method for preparing the silicon wafer cleaning solution of this embodiment adopts the above-mentioned raw material ratios of this embodiment, and other conditions are the same as those of Example 1.

[0100] Example 3 A silicon wafer cleaning solution is prepared from the following raw materials in parts by weight: 180 parts of dicyandiamide quaternary ammonium salt, 17 parts of nano-hydroxyapatite, 11 parts of ionic liquid, 4 parts of organic base, 55 parts of surfactant, 35 parts of oxidant, 3.5 parts of corrosion inhibitor, 6 parts of chelating agent and 550 parts of water.

[0101] The method for preparing the silicon wafer cleaning solution of this embodiment adopts the above-mentioned raw material ratios of this embodiment, and other conditions are the same as those of Example 1.

[0102] Example 4 A silicon wafer cleaning solution is prepared from the following raw materials in parts by weight: 150 parts of dicyandiamide quaternary ammonium salt, 15 parts of nano-hydroxyapatite, 8 parts of ionic liquid, 3 parts of organic base, 40 parts of surfactant, 30 parts of oxidant, 2 parts of corrosion inhibitor, 5 parts of chelating agent and 400 parts of water.

[0103] The method for preparing the silicon wafer cleaning solution of this embodiment adopts the above-mentioned raw material ratios of this embodiment, and other conditions are the same as those of Example 1.

[0104] Example 5 A silicon wafer cleaning solution is prepared from the following raw materials in parts by weight: 200 parts of dicyandiamide quaternary ammonium salt, 25 parts of nano-hydroxyapatite, 12 parts of ionic liquid, 7 parts of organic base, 60 parts of surfactant, 50 parts of oxidant, 4 parts of corrosion inhibitor, 8 parts of chelating agent and 600 parts of water.

[0105] The method for preparing the silicon wafer cleaning solution of this embodiment adopts the above-mentioned raw material ratios of this embodiment, and other conditions are the same as those of Example 1.

[0106] Example 6 A silicon wafer cleaning solution, which differs from Example 1 in that: The dicyandiamide quaternary ammonium salt is dicyandiamide dodecyltrimethylammonium chloride and dicyandiamide octyldimethylammonium bromide (mass ratio is 2:1), and the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium chloride (mass ratio is 1:2).

[0107] Example 7 A silicon wafer cleaning liquid, the raw materials of which are the same as those in Example 1.

[0108] The method for preparing a silicon wafer cleaning solution comprises the following steps: (a) Dispersion premixing: Nanohydroxyapatite (100 nm) was added to 60°C deionized water and ultrasonically dispersed for 20 min (power 850 W, frequency 50 kHz) to obtain a nanohydroxyapatite dispersion. This dispersion was then proportionally mixed with a portion of the ionic liquid (40% by weight of the total ionic liquid) and introduced into a microfluidic chip. Parameters: Channel structure: Y-shaped staggered microchannel (width 200 μm, depth 50 μm); flow rate control: 0.6 mL / min for the nanoparticle phase and 1.5 mL / min for the ionic liquid phase; dispersion uniformity >95%; a nanocomposite dispersion coated with ionic liquid was obtained (particle size distribution (PDI) <0.15).

[0109] (b) Main reaction stage: Dicyandiamide quaternary ammonium salt, corrosion inhibitor and dispersion were added to a high-speed shear reactor (25°C) in sequence, and shear mixed at 6000 rpm for 10 min to form a composite micelle system.

[0110] (c) Oxidation activation stage: ozone (6 L / min) was introduced and an oxidant and an organic base solution were added. The mass content of the oxidant was 35%, and the reaction was carried out for 15 min.

[0111] (d) Final mixing stage: Add chelating agent solution (2 mol / L) and surfactant, and stir at a low speed of 100 rpm for 40 min.

[0112] Example 8 A silicon wafer cleaning liquid, the raw materials of which are the same as those in Example 1.

[0113] The method for preparing a silicon wafer cleaning solution comprises the following steps: (a) Dispersion premixing: Nanohydroxyapatite (100 nm) was added to 45°C deionized water and ultrasonically dispersed for 35 min (power 700 W, frequency 30 kHz) to obtain a nanohydroxyapatite dispersion. This dispersion was then proportionally mixed with a portion of the ionic liquid (40% by weight of the total ionic liquid) and introduced into a microfluidic chip. Parameters: Channel structure: Y-shaped staggered microchannel (width 200 μm, depth 50 μm); flow rate control: 0.3 mL / min for the nanoparticle phase and 1 mL / min for the ionic liquid phase; dispersion uniformity >95%; a nanocomposite dispersion coated with ionic liquid was obtained (particle size distribution (PDI) <0.15).

[0114] (b) Main reaction stage: Dicyandiamide quaternary ammonium salt, corrosion inhibitor and dispersion were added to a high-speed shear reactor (25°C) in sequence, and shear mixed at 4000 rpm for 30 min to form a composite micelle system.

[0115] (c) Oxidation activation stage: ozone (2 L / min) was introduced and an oxidant and an organic base solution were added. The mass content of the oxidant was 25%, and the reaction was carried out for 15 min.

[0116] (d) Final mixing stage: Add chelating agent solution (2 mol / L) and surfactant, and stir at 300 rpm for 20 min.

[0117] Example 9 The method for preparing the silicon wafer cleaning solution differs from that of Example 1 in that: Premixing of dispersion: Add nanohydroxyapatite (80 nm) to 50°C deionized water and ultrasonically disperse for 30 min (power 800 W, frequency 40 kHz) to obtain nanohydroxyapatite dispersion. Then, add a portion of ionic liquid (40% by weight of the total ionic liquid) and continue ultrasonicating for 15 min to form a dispersion.

[0118] Comparative Example 1 The difference between the silicon wafer cleaning solution and Example 1 is as follows: No nanohydroxyapatite was added.

[0119] Comparative Example 2 The difference between the silicon wafer cleaning solution and Example 1 is as follows: No ionic liquid was added.

[0120] Comparative Example 3 The difference between the silicon wafer cleaning solution and Example 1 is as follows: No corrosion inhibitor was added.

[0121] Experimental example The cleaning liquid obtained in each embodiment is used to clean the silicon wafer, and then the waste cleaning liquid is recycled. The specific method is as follows: 1. Cleaning (1) Pre-cleaning: Ultrasonic cleaning with ultrapure water (18.2 MΩ·cm) for 5 min (40 kHz).

[0122] (2) Main cleaning: cleaning agent: silicon wafer = 5L: 1m²; temperature: 43~47℃; soak for 10min; megasonic auxiliary: 1 MHz megasonic wave, power density: 2W / cm².

[0123] (3) Rinsing: three-stage countercurrent rinsing (pure water flow rate is 10L / min).

[0124] (4) Drying: vacuum drying (pressure 10 -3 Pa).

[0125] 2. Waste liquid collection The waste cleaning solution is introduced into the ceramic membrane recovery system (pH is adjusted to 6.5-7.0 to prevent dissolution of nanoparticles).

[0126] Ceramic membrane recovery (solid-liquid separation) equipment: tubular ceramic membrane assembly (made of Al2O3).

[0127] Parameters: Membrane pore size: 50nm Operating pressure: 0.8MPa (transmembrane pressure difference) Temperature: 30℃.

[0128] Cross flow speed: 3m / s.

[0129] 3. Vacuum distillation regeneration Equipment: Short-path molecular distillation apparatus.

[0130] Parameters: temperature is 80°C; vacuum degree is 10 Pa; scraping speed is 200 rpm (forming a 0.1 mm renewal liquid film).

[0131] Regeneration process: a. Removal of adsorbed organic matter; b. Dissociation of ionic liquid from nanoparticles (recovery of [BMIM]Cl by evaporation-condensation); c. Regeneration of hydroxyl groups on the hydroxyapatite surface.

[0132] 4. Material Recycling The regenerated nano-hydroxyapatite re-enters the microfluidic premixing system in the cleaning agent preparation process; the recovered ionic liquid is added to the cleaning agent formula after purity testing (HPLC ≥ 99%).

[0133] The present invention is tested as follows: Metal ion removal efficiency testing utilizes the "GB / T 24578-2015 Total Reflection X-ray Fluorescence Spectrometry Test Method for Metal Contamination on Silicon Wafer Surfaces." The procedure involves placing the cleaned silicon wafer in a total reflection X-ray fluorescence spectrometer. Monochromatic X-rays incident at a grazing angle excite the surface metal ions to emit a characteristic fluorescence spectrum. Residual metal ions are calculated based on the linear relationship between the integrated fluorescence count rate and the surface density of the calibration element (detection limit as low as 10^10 atoms / cm²). Verification metric: Metal ion capture efficiency ≥ 99.7%.

[0134] Surface roughness testing: DIN 50453-2:2023 Determination of etch rate of semiconductor materials (optical method): The etch rate is calculated by analyzing the changes in the optical properties of the silica coating before and after etching (e.g., reflectivity and transmittance). A silica coating sample is prepared and etched in an etching solution at a preset time gradient (e.g., 1-minute intervals). An ellipsometer or laser interferometer is used to monitor the film thickness change in real time, and the etching amount per minute is calculated (accuracy ±0.02nm / min). Temperature control is maintained within ±0.1°C, and solution concentration fluctuation is ≤±0.5%.

[0135] Method for testing etching uniformity: optical method (DIN 50453-2:2023).

[0136] The test results are shown in Table 1.

[0137] Table 1 Test results

[0138] From the above, it can be seen that the silicon wafer cleaning solution of the present invention has excellent low-temperature stability, can clean silicon wafers with high precision and high efficiency, and can reduce the roughness of the surface thereof, and the cleaning solution has a long service life.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon wafer cleaning solution, characterized in that: Prepared from the following raw materials in parts by weight: 150-200 parts of dicyandiamide quaternary ammonium salt, 15-25 parts of nano-hydroxyapatite, 8-12 parts of ionic liquid, 3-7 parts of organic base, 40-60 parts of surfactant, 30-50 parts of oxidant, 2-4 parts of corrosion inhibitor, 5-8 parts of chelating agent and 400-600 parts of water.

2. The silicon wafer cleaning solution according to claim 1, characterized in that Prepared from the following raw materials in parts by weight: 160-180 parts of dicyandiamide quaternary ammonium salt, 17-22 parts of nano-hydroxyapatite, 9-11 parts of ionic liquid, 4-6 parts of organic base, 45-55 parts of surfactant, 35-45 parts of oxidant, 2.5-3.5 parts of corrosion inhibitor, 6-7 parts of chelating agent and 180-550 parts of water.

3. The silicon wafer cleaning solution according to claim 1, wherein Contains at least one of the following features (1) to (3): (1) The dicyandiamide quaternary ammonium salt includes at least one of dicyandiamide dodecyltrimethylammonium chloride and dicyandiamide octyldimethylammonium bromide; (2) The ionic liquid includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium chloride; (3) The particle size of the nano-hydroxyapatite is 50-100 μm.

4. The silicon wafer cleaning solution according to claim 1, characterized in that Contains at least one of the following features (1) to (5): (1) The surfactant includes polyethylene glycol octylphenyl ether; (2) The oxidant includes ammonium persulfate; (3) The corrosion inhibitor includes 1,2,3-benzotriazole; (4) The chelating agent includes disodium edetate; (5) The organic base includes tetramethylammonium hydroxide.

5. The method for preparing a silicon wafer cleaning solution according to any one of claims 1 to 4, wherein: The following steps are involved: (a) obtaining a dispersion of nanohydroxyapatite, water, and a portion of an ionic liquid; (b) first mixing the dispersion, the dicyandiamide quaternary ammonium salt, the corrosion inhibitor, and the remaining portion of the ionic liquid to obtain a first system; (c) mixing the first system with an oxidant and an organic base solution under ozone conditions to obtain a second system; (d) performing a second mixing of the second system with a surfactant and a chelating agent solution to obtain a silicon wafer cleaning solution.

6. The method for preparing a silicon wafer cleaning solution according to claim 5, wherein: Contains at least one of the following features (1) to (4): (1) The dispersion is subjected to a heating treatment during the obtaining process, wherein the heating treatment temperature is 45-60° C.; (2) A specific method for preparing the dispersion comprises: performing a first ultrasonic dispersion of the nano-hydroxyapatite and the water under heating conditions, and then adding a portion of the ionic liquid to perform a second ultrasonic dispersion; (3) During the preparation of the dispersion, the first ultrasonic dispersion time is 20 to 35 minutes, the first ultrasonic dispersion power is 700 to 850 W, and the first ultrasonic dispersion power is 30 to 50 kHz; the second ultrasonic dispersion time is 10 to 20 minutes; (4) The mass content of the partial ionic liquid in the total ionic liquid is 35% to 45%.

7. The method for preparing a silicon wafer cleaning solution according to claim 5, wherein: Contains at least one of the following features (1) to (5): (1) The first mixing speed is 4000-6000 rpm, and the first mixing time is 10-30 min; (2) The first mixing is carried out in a reactor at a temperature of 25-40° C.; (3) In the oxidant and organic base solution, the mass concentration of the oxidant is 25% to 35%; (4) The ozone flow rate is 2-6 L / min, and the ozone introduction time is 10-20 min; (5) The rotation speed of the second mixing is 100-300 rpm, and the time of the second mixing is 20-40 min.

8. The method for preparing a silicon wafer cleaning solution according to claim 5, wherein: During the preparation of the silicon wafer cleaning solution, the materials are mixed using a microfluidic mixing method; Preferably, the microfluidic mixing uses a Y-shaped glass chip with a channel width of 180-550 μm, a depth of 45-350 μm, and a tortuous channel length of 4-6 cm; Preferably, in step (a), the flow rate of the dispersion of the nano-hydroxyapatite and the water is controlled to be 0.3-0.6 mL / min, and the flow rate of the partial ionic liquid is controlled to be 1-1.5 mL / min.

9. A method for cleaning a silicon wafer, characterized in that: The following steps are involved: Pre-clean, main clean, rinse and dry the silicon wafers; The main cleaning adopts the cleaning agent according to any one of claims 1 to 4, or the silicon wafer cleaning solution obtained by the preparation method of the silicon wafer cleaning solution according to any one of claims 5 to 8.

10. The method for cleaning a silicon wafer according to claim 9, wherein: Contains at least one of the following features (1) to (2): (1) The main cleaning temperature is 43-47°C; the main cleaning soaking time is 8-15 minutes; the main cleaning is assisted by megasonics; the ratio of the cleaning agent to the silicon wafer is (4.5-5.5) L:1m 2 ; (2) Also included: recycling the waste cleaning liquid after injection and cleaning; the recycling process uses a ceramic membrane recovery system; the membrane pore size of the ceramic membrane recovery system is 45~55nm, the porosity is 40%~50%; the transmembrane pressure difference is 0.3~0.8MPa, the cross flow velocity is 2~4m / s, and the temperature is 38~45℃; Preferably, the mixed liquid after the recovery treatment is subjected to vacuum distillation regeneration to recover the ionic liquid and nano-hydroxyapatite; the temperature of the vacuum distillation regeneration is 50~85°C, the vacuum degree of the vacuum distillation regeneration is 8~12Pa, and the scraping speed is 150~250rpm.

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