Indium phosphide polishing solution and preparation method thereof

Abstract

The invention discloses an indium phosphide polishing solution and a preparation method thereof. The indium phosphide polishing solution comprises a grinding material, a suspending agent, a dispersing agent, a first oxidizing agent, a second oxidizing agent, a surfactant, an acid-base regulator, a photocatalyst and a solvent, the grinding material is spherical aluminum oxide with the particle size range of 30-100 nm, the solvent comprises water, and the photocatalyst is configured to oxidize hydroxyl radicals and water molecules into hydroxyl radicals under light irradiation. In the indium phosphide polishing solution provided by the embodiment of the invention, the spherical aluminum oxide with the particle size of 30-100 nm is adopted as a grinding material, so that the surface damage of a workpiece is effectively solved, the surface roughness is reduced, the flatness is improved, and meanwhile, the phenomena that the indium phosphide surface is easy to cause corrosion and the solution is difficult to clean and easy to remain are avoided. The photocatalyst can adjust the chemical reaction rate of indium phosphide, improve the polishing rate of the indium phosphide polishing solution to indium phosphide, and meanwhile avoid hard spots easily appearing on the surface of a machined part due to imbalance of chemical reaction and mechanical action.

Description

Technical Field

[0001] This invention relates to the field of polishing slurry technology, and more specifically, to an indium phosphide polishing slurry and a method for preparing the indium phosphide polishing slurry. Background Technology

[0002] Indium phosphide (InP), as a third-generation semiconductor material, possesses irreplaceable advantages in fields such as 5G communication, optical modules, high-frequency millimeter-wave devices, and space solar cells. It features a direct-transition band structure, a wide bandgap, high electric field drift velocity, good thermal conductivity, and strong radiation resistance. However, indium phosphide is soft and brittle with low hardness (Mohs hardness of 3), making it prone to surface damage during polishing. Therefore, it places extremely high demands on the polishing fluid and processing techniques.

[0003] In related technologies, indium phosphide polishing slurries are divided into mechanical polishing slurries and chemical mechanical polishing slurries. Mechanical polishing slurries do not have a direct chemical reaction with the workpiece and rely on mechanical operations such as abrasives and polishing pads, which can easily cause damage to the surface of the workpiece and the roughness cannot meet the requirements of semiconductor substrates and chips. Therefore, chemical mechanical polishing slurries are the optimal choice to achieve global planarization, low roughness and high removal rate.

[0004] Chemical mechanical polishing slurries need to achieve a synergistic effect of chemical and mechanical action. Inappropriate abrasives may cause corrosion on the surface of indium phosphide, and the solution may be difficult to clean and leave residues. This can also significantly affect the life of the polishing pad and the uniformity of corrosion on the machine. Alternatively, excessive mechanical action may result in severe damage to the surface of the workpiece. Summary of the Invention

[0005] The present invention provides an indium phosphide polishing slurry and a method for preparing the indium phosphide polishing slurry, which reduces or eliminates surface damage to the workpiece, avoids the impact of strong acid solutions on the life of the polishing pad and the corrosion of the machine, and avoids the problem that strong acid solutions are difficult to clean and easily leave residues.

[0006] The indium phosphide polishing slurry provided in this embodiment of the invention includes an abrasive, a suspending agent, a dispersant, a first oxidant, a second oxidant, a surfactant, an acid-base regulator, a photocatalyst, and a solvent; the abrasive is alumina with a particle size range of 30nm-100nm, the solvent includes water, and the photocatalyst is configured to oxidize hydroxide ions and water molecules into hydroxyl radicals under light irradiation.

[0007] In the indium phosphide polishing solution provided in the embodiments of the present invention, the indium phosphide polishing solution uses 30nm-100nm alumina as the abrasive, which effectively solves the surface damage of the processed parts, reduces surface roughness and improves flatness, while also avoiding the easy corrosion of the indium phosphide surface and the difficulty in cleaning the solution and the easy residue.

[0008] In related technologies, the commonly used abrasives for indium phosphide are 30nm-100nm silicon oxide and 100nm-1000nm aluminum oxide. When using silicon oxide as the abrasive, the indium phosphide polishing slurry is acidic, with a pH of 1-5, but the removal rate is low at 0.1-0.3 μm / min. The indium phosphide surface is easily corroded, and silicon oxide is difficult to clean and tends to leave residue. Furthermore, the strongly acidic solution significantly affects the lifespan of the polishing pad and the corrosion of the polishing machine. When using 100nm-1000nm aluminum oxide as the abrasive, the indium phosphide polishing slurry is alkaline, with a pH of alkaline 9-13, and the removal rate can reach 0.8μm / min-1.2μm / min. However, the surface damage to the workpiece is more severe than with silicon oxide polishing slurries, and the surface roughness is higher.

[0009] The indium phosphide polishing slurry provided in this invention uses 30-100nm alumina as an abrasive. Ordinary alumina has sharp edges, while indium phosphide is soft and brittle, easily causing scratches and resulting in high roughness. Compared to using 100nm-1000nm alumina as an abrasive, this reduces or eliminates surface damage and roughness of the workpiece. Compared to using 30nm-100nm silicon oxide as an abrasive, it avoids the impact of strong acid solutions on the polishing pad's lifespan and machine corrosion, as well as the problem of strong acid solutions being difficult to clean and prone to residue. A photocatalyst can regulate the chemical reaction rate of indium phosphide, improving the polishing rate of the indium phosphide polishing slurry on indium phosphide, while avoiding an imbalance between chemical reaction and mechanical action, thus preventing pitting on the workpiece surface and increasing the removal rate to 1.0μm / min-1.3μm / min. This invention uses 30nm-100nm spherical alumina, effectively reducing the surface roughness of the workpiece to ≤0.2nm and the flatness to ≤1μm.

[0010] In some embodiments, the indium phosphide polishing slurry comprises the following components in weight percentages: abrasive: 5%-30%, suspending agent: 0.2%-3%, dispersant: 0.1%-2%, primary oxidant: 1%-10%, secondary oxidant: 0.2%-5%, surfactant: 0.2%-3%, pH adjuster: 0.1%-2%, and photocatalyst: 0.1%-2%.

[0011] In some embodiments, the photocatalyst includes at least one selected from titanium oxide, zirconium oxide, zinc oxide, ferric oxide, tin oxide, and zinc sulfide, and the amount of photocatalyst added is 0.1%-2%, preferably 0.3%-0.8%.

[0012] In some embodiments, the suspending agent can fully suspend the abrasive, increasing the service life of the abrasive. The suspending agent includes at least one of inorganic bentonite, organic bentonite, magnesium aluminum silicate, sodium carboxymethyl cellulose, xanthan gum, lithium magnesium silicate, and carbomer. The amount of suspending agent added is 0.2%-3%, preferably 0.5%-1.0%.

[0013] In some embodiments, the dispersant helps to prevent abrasive agglomeration by electrostatic repulsion and steric hindrance, thereby reducing the risk of scratches. The dispersant includes at least one of aqueous sodium polyacrylate, sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium hypophosphite, sodium silicate, aluminum nitrate, and polyethylene glycol. The amount of dispersant added is 0.1%-2%, preferably 0.3%-0.8%.

[0014] In some embodiments, the first oxidant includes at least one of sodium hypochlorite, sodium chlorate, sodium perchlorate, potassium perchlorate, and hydrogen peroxide. All first oxidants can instantaneously release free [O], possessing extremely strong oxidizing properties and capable of producing an oxide layer on the surface of indium phosphide. The amount of the first oxidant added is 1%-10%, preferably 3%-6%.

[0015] In some embodiments, the second oxidant includes at least one selected from potassium nitrate, sodium nitrate, potassium dichromate, aluminum nitrate, sodium orthovanadate, sodium metavanadate, and potassium permanganate. The second oxidant provides a stable oxidizing atmosphere for the polishing slurry and can enhance the oxidizing activity of the first oxidant; the addition amount is 0.2%-5%, preferably 0.5%-1.5%.

[0016] In some embodiments, the surfactant includes at least one selected from nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sodium dodecyl sulfate, sodium fatty acid methyl ester sulfonate, and dodecyl sulfonic acid. The surfactant is a nonionic or anionic surfactant that can improve the dispersibility and wettability of the abrasive. The surfactant addition amount is 0.2%-3%, preferably 0.3%-1.0%.

[0017] In some embodiments, the acid-base regulator is used to adjust the pH of the indium phosphide polishing solution, and includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, diethanolamine, potassium formate, and tetrasodium ethylenediaminetetraacetate. The amount of acid-base regulator added is 0.1%-2%, preferably 0.3%-1.2%.

[0018] The method for preparing indium phosphide polishing solution provided in this invention includes the following steps:

[0019] Add a dispersant to the first solvent and stir at a speed of 600r / min-1000r / min for 1min-5min. Then add alumina powder with a particle size range of 30nm-100nm to the first solvent, keep stirring and turn on ultrasonic dispersion for 1-2 hours to obtain the first solution.

[0020] Add a suspending agent to the second solvent and stir at a speed of 600 r / min-1000 r / min for 30 min-60 min to obtain a second solution. The first solvent and the second solvent are water of equal mass.

[0021] The second solution was added to the first solution at a rate of 0.5 L / min, and stirred at a speed of 1000 r / min-1500 r / min. The ultrasonic treatment was turned on and stirring was maintained for 1 hour to obtain the third solution.

[0022] While maintaining stirring and sonication, the first oxidant, the second oxidant, the photocatalyst, and the surfactant were added to the third solution sequentially at a rate of 1 g / min-5 g / min to obtain the fourth solution.

[0023] An acid-base adjuster is added dropwise to the fourth solution to adjust the pH value to the target range, thereby obtaining the indium phosphide polishing solution. Thus, the method for preparing the indium phosphide polishing solution provided in this embodiment of the invention yields the indium phosphide polishing solution provided in this embodiment of the invention.

[0024] This invention provides an indium phosphide polishing slurry and a method for preparing the indium phosphide polishing slurry. The indium phosphide polishing slurry includes an abrasive, a suspending agent, a dispersant, a first oxidant, a second oxidant, a surfactant, an acid-base regulator, a photocatalyst, and a solvent; the abrasive is alumina with a particle size range of 30 nm-100 nm, the solvent includes water, and the photocatalyst is configured to oxidize hydroxide ions and water molecules into hydroxyl radicals under light irradiation.

[0025] In the indium phosphide polishing solution provided in the embodiments of the present invention, the indium phosphide polishing solution uses 30nm-100nm alumina as the abrasive, which effectively solves the surface damage of the processed parts, and also avoids the easy corrosion of the indium phosphide surface and the difficulty in cleaning the solution and the easy residue.

[0026] The indium phosphide polishing slurry provided in this invention uses 30-100nm alumina as an abrasive, which reduces or eliminates surface damage to the workpiece compared to using 100nm-1000nm alumina. Compared to using 30nm-100nm silicon oxide as an abrasive, it avoids the impact of strong acid solutions on the lifespan of the polishing pad and the corrosion of the machine, as well as the problem of strong acid solutions being difficult to clean and prone to residue. The photocatalyst can regulate the chemical reaction rate of indium phosphide, improving the polishing rate of the indium phosphide polishing slurry on indium phosphide, while avoiding pitting on the surface of the workpiece that is prone to occur due to an imbalance between chemical reaction and mechanical action.

[0027] Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the invention. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0029] Figure 1 This is a method for preparing indium phosphide polishing solution according to an embodiment of the present invention. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are optional and are only used to explain the embodiments of the present invention, and should not be construed as limiting the embodiments of the present invention.

[0031] Indium phosphide (InP), as a third-generation semiconductor material, possesses irreplaceable advantages in fields such as 5G communication, optical modules, high-frequency millimeter-wave devices, and space solar cells. It features a direct-transition band structure, a wide bandgap, high electric field drift velocity, good thermal conductivity, and strong radiation resistance. However, indium phosphide is soft and brittle with low hardness (Mohs hardness of 3), making it prone to surface damage during polishing. Therefore, it places extremely high demands on the polishing fluid and processing techniques.

[0032] In related technologies, indium phosphide polishing slurries are divided into mechanical polishing slurries and chemical mechanical polishing slurries. Mechanical polishing slurries do not have a direct chemical reaction with the workpiece and rely on mechanical operations such as abrasives and polishing pads, which can easily cause damage to the surface of the workpiece and the roughness cannot meet the requirements of semiconductor substrates and chips. Therefore, chemical mechanical polishing slurries are the optimal choice to achieve global planarization, low roughness and high removal rate.

[0033] Chemical mechanical polishing slurries need to achieve a synergistic effect of chemical and mechanical action. Inappropriate abrasives can easily cause corrosion of indium phosphide surfaces, making silicon oxide difficult to clean and prone to residue, significantly impacting polishing pad life and the uniformity of machine corrosion. Alternatively, excessive mechanical action can lead to severe surface damage to the workpiece. Conversely, choosing an unsuitable abrasive particle size can result in an imbalance between chemical reaction and mechanical action, potentially causing pitting on the workpiece surface.

[0034] To address the aforementioned technical problems, embodiments of the present invention provide an indium phosphide polishing solution and a method for preparing the indium phosphide polishing solution (e.g., ...). Figure 1 As shown in the figure, it can effectively solve the surface damage of the processed parts, and at the same time avoid the impact of strong acid solutions on the life of the polishing pad and the corrosion of the machine.

[0035] The indium phosphide polishing solution provided in this embodiment of the invention is prepared by the method for preparing indium phosphide polishing solution provided in this embodiment of the invention.

[0036] The indium phosphide polishing slurry provided in this invention comprises an abrasive, a suspending agent, a dispersant, a first oxidant, a second oxidant, a surfactant, a pH adjuster, a photocatalyst, and a solvent. The abrasive is alumina with a particle size range of 30 nm to 100 nm, the solvent includes water, and the photocatalyst is configured to oxidize hydroxide ions and water molecules into hydroxyl radicals under light irradiation. In this invention, spherical alumina is used to further reduce surface roughness and improve overall smoothness.

[0037] Specifically, the oxidant can transform the surface of indium phosphide into a soft oxide layer, which is easily removed by abrasive machinery. The abrasive can scrape away the soft oxide layer through physical friction, and achieve surface planarization of indium phosphide through shear force. The suspending agent prevents abrasive agglomeration, and the dispersant prevents abrasive sedimentation. Both suspending and dispersing agents can maintain uniform suspension of abrasive particles through electrostatic repulsion or steric hindrance. The surfactant can reduce surface tension, allowing the polishing slurry to spread evenly on the substrate surface, reducing bubble interference at the polishing pad-wafer interface, assisting the dispersant in stabilizing abrasive particles, and reducing the risk of mechanical damage. The pH adjuster regulates the pH of the indium phosphide polishing slurry, controlling the activity of the oxidant, the effectiveness of the complexing agent, the dispersion stability of the abrasive, and acting as a corrosion inhibitor.

[0038] In related technologies, the commonly used abrasives for indium phosphide are 30nm-100nm silicon oxide and 100nm-1000nm spherical alumina. When using silicon oxide as the abrasive, the indium phosphide polishing slurry is acidic, with a pH of 1-5, but the removal rate is low at 0.1-0.3 μm / min. The indium phosphide surface is easily corroded, and silicon oxide is difficult to clean and tends to remain. Furthermore, the strongly acidic solution significantly affects the lifespan of the polishing pad and the uniformity of corrosion on the machine tool. When using 100nm-1000nm spherical alumina as the abrasive, the indium phosphide polishing slurry is alkaline, with a pH of alkaline 9-13, and the removal rate can reach 0.8μm / min-1.2μm / min. However, the surface damage to the workpiece is more severe than with silicon oxide polishing slurries.

[0039] The indium phosphide polishing slurry provided in this invention uses 30-100nm spherical alumina as an abrasive. Compared to using 100-1000nm alumina, this reduces or eliminates surface damage to the workpiece, lowers surface roughness, and improves smoothness. Compared to using 30-100nm silicon oxide as an abrasive, it avoids the impact of strong acid solutions on the polishing pad's lifespan and machine corrosion, as well as the problem of strong acid solutions being difficult to clean and prone to residue. The photocatalyst can regulate the chemical reaction rate of indium phosphide, improving the polishing rate of the indium phosphide polishing slurry on indium phosphide, while avoiding an imbalance between chemical reaction and mechanical action, thus preventing pitting on the workpiece surface and increasing the removal rate to 1.0μm / min-1.3μm / min. Using 30-100nm spherical alumina as an abrasive effectively reduces the surface roughness of the workpiece to ≤0.2nm and the smoothness to ≤1μm, while also facilitating the formation of an oxide layer under the action of the first oxidant, resulting in a rapid reaction. Furthermore, compared to alumina with smaller particle size, this invention can increase reaction controllability and ensure the equilibrium performance of the reaction. Based on small-particle-size nano-alumina, this invention uses spherical alumina with a particle size of 30nm-40nm, which can meet various reaction requirements. Combined with surfactants and a primary oxidant, it achieves a faster reaction rate and a smoother surface.

[0040] Without the addition of a photocatalyst to assist polishing, the chemical reaction rate of indium phosphide is difficult to control. When using abrasives with low Mohs hardness, the removal rate is too low, and it is easy to cause an imbalance between chemical reaction and mechanical action, which in turn leads to pitting on the surface of the workpiece.

[0041] Indium phosphide polishing slurry contains hydroxide ions and water molecules. Under light irradiation, the photocatalyst oxidizes the hydroxide ions and water molecules adsorbed on the surface of the photocatalyst into hydroxyl radicals. The hydroxyl radicals have extremely strong oxidizing power, producing an oxide layer on the surface of indium phosphide, thereby increasing the removal rate of indium phosphide and improving the polishing rate of indium phosphide polishing slurry on indium phosphide. At the same time, it avoids the imbalance between chemical reaction and mechanical action, thus avoiding pitting on the surface of the processed parts.

[0042] In some embodiments, the indium phosphide polishing slurry comprises the following components in weight percentages: abrasive: 5%-30%, suspending agent: 0.2%-3%, dispersant: 0.1%-2%, primary oxidant: 1%-10%, secondary oxidant: 0.2%-5%, surfactant: 0.2%-3%, pH adjuster: 0.1%-2%, and photocatalyst: 0.1%-2%.

[0043] The components of the indium phosphide polishing solution provided in the embodiments of the present invention will be further described below through multiple examples and comparative examples.

[0044] As shown in Table 1 below, the indium phosphide polishing slurry provided in Example 1 uses spherical alumina with an abrasive of 30nm-100nm. The indium phosphide polishing slurry includes the following components by weight percentage: abrasive: 10%, first oxidant: 8%, second oxidant: 1.5%, acid-base adjuster: 0.1%, and photocatalyst: 1%.

[0045] The indium phosphide polishing slurry provided in Example 2 uses spherical alumina with an abrasive of 30nm-100nm. The indium phosphide polishing slurry includes the following components by weight percentage: abrasive: 5%, first oxidant: 10%, second oxidant: 2%, acid-base adjuster: 0.1%, and photocatalyst: 1.5%.

[0046] The indium phosphide polishing slurry provided in Example 3 uses spherical alumina with an abrasive of 30nm-100nm. The indium phosphide polishing slurry includes the following components by weight percentage: abrasive: 20%, first oxidant: 5%, second oxidant: 0.5%, acid-base adjuster: 0.1%, and photocatalyst: 0.5%.

[0047] The indium phosphide polishing slurry provided in Comparative Example 1 uses alumina with an abrasive of 100nm-500nm. The indium phosphide polishing slurry comprises the following components by weight percentage: abrasive: 10%, primary oxidant: 10%, and acid-base adjuster: 0.1%. The indium phosphide polishing slurry provided in Comparative Example 1 does not contain secondary oxidant or photocatalyst components.

[0048] The indium phosphide polishing slurry provided in Comparative Example 2 uses alumina with an abrasive of 100nm-500nm. The indium phosphide polishing slurry comprises the following components by weight percentage: abrasive: 10%, primary oxidant: 10%, primary oxidant: 2%, and acid-base adjuster: 0.1%. The indium phosphide polishing slurry provided in Comparative Example 2 does not contain any photocatalyst components.

[0049] The indium phosphide polishing slurry provided in Comparative Example 3 uses silicon oxide as the abrasive. The indium phosphide polishing slurry comprises the following components by weight percentage: abrasive: 20%, primary oxidant: 10%, primary oxidant: 2%, and acid-base adjuster: 0.1%. The indium phosphide polishing slurry provided in Comparative Example 3 does not contain any photocatalyst components.

[0050] The indium phosphide polishing slurry provided in Comparative Example 4 uses silicon oxide as the abrasive. The indium phosphide polishing slurry includes the following components by weight percentage: abrasive: 20%, primary oxidant: 10%, primary oxidant: 2%, acid-base adjuster: 0.1%, and photocatalyst: 1.5%.

[0051] The indium phosphide polishing slurry provided in Comparative Example 5 uses alumina with an abrasive of 30nm-100nm. The indium phosphide polishing slurry comprises the following components by weight percentage: abrasive: 10%, primary oxidant: 8%, acid-base adjuster: 0.1%, and photocatalyst: 1%. The indium phosphide polishing slurry provided in Comparative Example 5 does not contain a secondary oxidant component.

[0052] The indium phosphide polishing slurry provided in Comparative Example 6 uses alumina with an abrasive of 30nm-100nm. The indium phosphide polishing slurry comprises the following components by weight percentage: abrasive: 10%, primary oxidant: 8%, acid-base adjuster: 0.1%, and secondary oxidant: 1.5%. The indium phosphide polishing slurry provided in Comparative Example 6 does not contain any photocatalyst components.

[0053] The indium phosphide polishing slurry provided in Comparative Example 7 uses alumina with an abrasive of 30nm-100nm. The indium phosphide polishing slurry comprises the following components by weight percentage: abrasive: 10%, acid-base adjuster: 0.1%, secondary oxidant: 1.5%, and photocatalyst: 1%. The indium phosphide polishing slurry provided in Comparative Example 7 does not contain the primary oxidant component.

[0054] Table 1:

[0055]

[0056] As shown in Table 2 below, the indium phosphide polishing solutions provided in Examples 1, 2, and 3 exhibit scratch lengths of less than 2 cm, yields of greater than 90%, removal rates higher than 0.9, roughness lower than 0.15, and no pitting. Therefore, Examples 1, 2, and 3 are preferred embodiments of the present invention.

[0057] The indium phosphide polishing solutions provided in Comparative Examples 1 and 2 had scratch lengths greater than 30 cm, roughness greater than 0.4, and yields less than 20%.

[0058] The removal rates of the indium phosphide polishing solutions provided in Comparative Examples 3, 4 and 5 were less than 0.9.

[0059] Comparative Examples 6 and 7 showed pitting.

[0060] Table 2:

[0061] Case Scratch length (cm) Removal rate pockmarks roughness Flatness TTV (μm) Yield Example 1 1.5 1.15 none 0.11 0.78 95.1％ Example 2 1.2 0.98 none 0.09 0.85 96.3％ Example 3 1.6 1.13 none 0.12 0.69 93.8％ Comparative Example 1 46.2 0.91 none 0.43 2.15 20.1％ Comparative Example 2 51.3 1.08 none 0.58 2.32 19.7％ Comparative Example 3 1.3 0.18 none 0.11 1.26 91.3％ Comparative Example 4 2.6 0.35 none 0.12 1.39 92.4％ Comparative Example 5 1.8 0.81 none 0.11 0.91 94.8％ Comparative Example 6 2.6 0.53 have 0.37 0.81 58.3％ Comparative Example 7 3.1 0.45 have 0.46 0.89 42.5％

[0062] In some embodiments, the photocatalyst includes at least one of titanium oxide, zirconium oxide, zinc oxide, ferric oxide, tin oxide, and zinc sulfide.

[0063] Specifically, indium phosphide polishing solutions contain hydroxyl and water molecules. Under light irradiation, the photocatalyst oxidizes the hydroxyl and water molecules adsorbed on its surface into hydroxyl radicals. These hydroxyl radicals have extremely strong oxidizing power, producing an oxide layer on the indium phosphide surface, thereby increasing the removal rate of indium phosphide and improving the polishing speed of the indium phosphide polishing solution. Titanium oxide, zirconium oxide, zinc oxide, ferric oxide, tin oxide, and zinc sulfide can all oxidize the hydroxyl and water molecules adsorbed on the photocatalyst surface into hydroxyl radicals under light irradiation, producing an oxide layer on the indium phosphide surface, thus aiding in the removal of indium phosphide.

[0064] In some embodiments, the suspending agent includes at least one of inorganic bentonite, organic bentonite, magnesium aluminum silicate, sodium carboxymethyl cellulose, xanthan gum, lithium magnesium silicate, and carbomer.

[0065] Suspension agents effectively suspend abrasive particles, increasing their lifespan. Specifically, suspending agents maintain the stability of the abrasive particles by increasing the viscosity of the liquid phase or forming a three-dimensional network structure, ensuring long-term uniform suspension. Among these, high molecular weight polymers such as inorganic bentonite, organic bentonite, magnesium aluminum silicate, sodium carboxymethyl cellulose (CMC), xanthan gum, lithium magnesium silicate, and carbomer, or inorganic thickeners, can all increase viscosity, enabling long-term uniform suspension of the abrasive particles and maintaining their stability.

[0066] In some embodiments, the dispersant includes at least one of aqueous sodium polyacrylate, sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium hypophosphite, sodium silicate, aluminum nitrate, and polyethylene glycol.

[0067] Dispersants help prevent abrasive agglomeration through electrostatic repulsion and steric hindrance, thus reducing the risk of scratches. Specifically, dispersants regulate particle surface properties, allowing the abrasive to maintain its independent dispersion at its native particle size in the liquid phase, thereby preserving the stability of the abrasive. Among these, water-based sodium polyacrylate, sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium hypophosphite, sodium silicate, aluminum nitrate, polyethylene glycol homopolymers, polyphosphates, and anionic surfactants can all regulate particle surface properties to maintain the independent dispersion of the abrasive at its native particle size in the liquid phase.

[0068] In some embodiments, the first oxidant includes at least one of sodium hypochlorite, sodium chlorate, sodium perchlorate, potassium perchlorate, and hydrogen peroxide.

[0069] Specifically, the oxidant used in indium phosphide polishing slurries can include a primary oxidant. During the chemical reaction, the primary oxidant instantaneously releases free peroxide ions, all of which have extremely strong oxidizing properties and can rapidly produce a soft oxide layer on the surface of indium phosphide, which is easily removed by abrasive machinery. Among them, materials such as sodium hypochlorite, sodium chlorate, sodium perchlorate, potassium perchlorate, and hydrogen peroxide, which can release free peroxide ions during the chemical reaction, all have extremely strong oxidizing properties and can rapidly produce a soft oxide layer on the surface of indium phosphide, which is easily removed by abrasive machinery, thereby increasing the removal rate of indium phosphide.

[0070] In some embodiments, the second oxidant includes at least one of potassium nitrate, sodium nitrate, potassium dichromate, aluminum nitrate, sodium orthovanadate, sodium metavanadate, and potassium permanganate.

[0071] Specifically, the oxidant used in indium phosphide polishing slurry may include a secondary oxidant. During the chemical reaction, the secondary oxidant provides a stable oxidizing atmosphere for the polishing slurry, synergistically enhancing the oxidizing activity of the primary oxidant and promoting the redox reaction on the indium phosphide surface, thereby aiding in the removal of indium phosphide. Materials such as potassium nitrate, sodium nitrate, potassium dichromate, aluminum nitrate, sodium orthovanadate, sodium metavanadate, and potassium permanganate, which provide a stable oxidizing atmosphere for the polishing slurry during the chemical reaction, can synergistically work with the primary oxidant to promote the redox reaction on the indium phosphide surface, thus facilitating the removal of indium phosphide.

[0072] In some embodiments, the surfactant includes at least one of nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sodium lauryl sulfate, sodium fatty acid methyl ester sulfonate, and dodecyl sulfonic acid.

[0073] Surfactants, whether nonionic or anionic, enhance the dispersibility and wettability of abrasive particles. They interact with spherical alumina to increase its smoothness, thus improving overall flatness. Specifically, surfactants reduce surface tension, allowing the polishing slurry to spread evenly on the substrate surface, reducing bubble interference at the polishing pad-wafer interface, assisting the dispersant in stabilizing abrasive particles, and reducing the risk of mechanical damage. Anionic and nonionic materials such as nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sodium dodecyl sulfate, sodium fatty acid methyl ester sulfonate, and dodecyl sulfonic acid can reduce surface tension, allowing the polishing slurry to spread evenly on the substrate surface, reducing bubble interference at the polishing pad-wafer interface, assisting the dispersant in stabilizing abrasive particles, and reducing the risk of mechanical damage.

[0074] In some embodiments, the acid-base regulator includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, diethanolamine, potassium formate, and ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na).

[0075] Specifically, the pH of indium phosphide polishing slurry is one of the most critical control parameters, as it strongly affects the activity of the oxidant, the effectiveness of the compounding agents, the dispersion stability of the abrasive, and the effect of the corrosion inhibitor. The role of pH adjusters is to regulate the pH of the indium phosphide polishing slurry, thereby controlling the activity of the oxidant, the effectiveness of the compounding agents, the dispersion stability of the abrasive, and the effect of the corrosion inhibitor.

[0076] The indium phosphide polishing slurry provided in this embodiment of the invention uses 30-100nm alumina as the abrasive, and the acid-base adjuster is an alkaline material such as sodium hydroxide, potassium hydroxide, triethanolamine, diethanolamine, potassium formate, and tetrasodium ethylenediaminetetraacetate. Compared with using 30-100nm silicon oxide as the abrasive, it avoids the impact of strong acid solutions on the polishing pad life and machine corrosion, as well as the problems of strong acid solutions being difficult to clean and prone to residue.

[0077] This invention also provides a method for preparing an indium phosphide polishing slurry, the method comprising the following steps:

[0078] Step 01: Add a dispersant to the first solvent and stir at a speed of 600r / min-1000r / min for 1min-5min. Then add alumina powder with a particle size range of 30-100nm to the first solvent, keep stirring and turn on ultrasonic dispersion for 1-2 hours to obtain the first solution.

[0079] In step 01, the first solvent can be 50% water in the calculated proportion, and the dispersant includes at least one of aqueous sodium polyacrylate, sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium hypophosphite, sodium silicate, aluminum nitrate, and polyethylene glycol. The dispersant is added to 50% water in the calculated proportion, and the mixture is stirred at 600-1000 rpm for 1-5 minutes. Then, alumina powder with a particle size range of 30 nm-100 nm is added to the first solvent, and the mixture is stirred while ultrasonically dispersed for 1-2 hours to obtain the first solution.

[0080] Preliminary mixing allows for initial mixing of the dispersant and abrasive in water, preventing component denaturation due to localized overheating during ultrasonication. Ultrasonic dispersion can address nano-agglomeration issues that are inaccessible to stirring. During ultrasonic dispersion, the microbubbles generated by the ultrasound waves rupture, creating localized high pressure and high temperature, which breaks down abrasive agglomerates. 600 r / min is the starting point for the critical shear rate; below this value, the dispersant may not be adequately wetted, while the upper limit of 1000 r / min is to prevent air entrainment.

[0081] Step 02: Add a suspending agent to the second solvent and stir at a speed of 600r / min-1000r / min for 30min-60min to obtain a second solution. The first solvent and the second solvent are water of the same mass.

[0082] In step 02, the second solvent can be water, which accounts for 50% of the calculated proportion. The suspending agent includes at least one of inorganic bentonite, organic bentonite, magnesium aluminum silicate, sodium carboxymethyl cellulose, xanthan gum, lithium magnesium silicate, and carbomer. The suspending agent is added to the second solvent, and the mixture is stirred at 600 rpm to 1000 rpm for 30-60 minutes to obtain the second solution.

[0083] The stirring process after adding the suspending agent to the second solvent is a crucial step in the preparation of the polishing slurry, directly affecting the activation effect and final dispersion stability of the suspending agent. 600 r / min is the starting point of the critical shear rate; below this value, the suspending agent may not be sufficiently wetted. The upper limit of 1000 r / min is to avoid air entrainment, ensuring that the polymer suspending agent is stirred for a sufficient time to ensure that the molecular chains are fully stretched.

[0084] Step 03: Add the second solution to the first solution at a rate of 0.5 L / min, stir at a speed of 1000 r / min-1500 r / min, turn on the sonication and keep stirring for 1 hour to obtain the third solution.

[0085] In step 03, the second solution is added to the first solution at a rate of 0.5 L / min, and the mixture is stirred at a speed of 1000 r / min-1500 r / min. Ultrasonication is then activated and stirring is maintained for 1 hour to obtain the third solution.

[0086] In the preparation of indium phosphide polishing slurry, adding the second solution to the first solution at a controlled rate and applying high-energy mixing is a key step to achieve uniform dispersion at the molecular level.

[0087] Step 04: While maintaining stirring and sonication, add the first oxidant, second oxidant, photocatalyst, and surfactant sequentially to the third solution at a rate of 1 g / min-5 g / min to obtain the fourth solution. During the chemical reaction, the first oxidant instantaneously releases free peroxide ions [Oˉ], which have extremely strong oxidizing properties and can rapidly produce a soft oxide layer on the surface of indium phosphide, which is easily removed by abrasive machinery. The second oxidant provides a stable oxidizing atmosphere for the polishing slurry and works synergistically with the first oxidant to facilitate the redox reaction on the surface of indium phosphide, thereby aiding in the removal of indium phosphide.

[0088] In step 04, while maintaining stirring and sonication, the first oxidant, the second oxidant, the photocatalyst, and the surfactant are added sequentially to the third solution at a rate of 1-5 g / min to obtain the fourth solution. The photocatalyst includes at least one of titanium dioxide, zirconium oxide, zinc oxide, ferric oxide, tin oxide, and zinc sulfide. The first oxidant includes at least one of sodium hypochlorite, sodium chlorate, sodium perchlorate, potassium perchlorate, and hydrogen peroxide. The second oxidant includes at least one of potassium nitrate, sodium nitrate, potassium dichromate, aluminum nitrate, sodium orthovanadate, sodium metavanadate, and potassium permanganate. The surfactant includes at least one of nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sodium dodecyl sulfate, sodium fatty acid methyl ester sulfonate, and dodecyl sulfonic acid.

[0089] Indium phosphide polishing slurries contain hydroxyl and water molecules. Under light or ultraviolet irradiation, the photocatalyst oxidizes the hydroxyl and water molecules adsorbed on its surface into hydroxyl radicals. These hydroxyl radicals have extremely strong oxidizing power, producing an oxide layer on the indium phosphide surface, thereby increasing the removal rate of indium phosphide and improving the polishing speed of the indium phosphide polishing slurry. Surfactants can reduce surface tension, allowing the polishing slurry to spread evenly on the substrate surface, reducing bubble interference at the polishing pad-wafer interface, assisting the dispersant in stabilizing abrasive particles, and reducing the risk of mechanical damage.

[0090] Step 05: Add an acid-base adjuster to the fourth solution to adjust the pH value to the target range, thus obtaining the indium phosphide polishing solution.

[0091] In step 05, an acid-base adjuster is added dropwise to the fourth solution to adjust the pH value to the target range, thus obtaining the indium phosphide polishing solution. The alkali adjuster includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, diethanolamine, potassium formate, and tetrasodium ethylenediaminetetraacetate.

[0092] The components in the indium phosphide polishing liquid obtained by the preparation method provided in this invention can be in the following weight percentages: abrasive: 5%-30%, suspending agent: 0.2%-3%, dispersant: 0.1%-2%, first oxidant: 1%-10%, second oxidant: 0.2%-5%, surfactant: 0.2%-3%, and acid-base adjuster: 0.1%-2%.

[0093] The parameters of the indium phosphide polishing slurry are as follows: Pressure: 100-300 g / cm³ 2 Rotation speed: 30r / min-60r / min, processing time: 5min-10min, the polishing pad for the indium phosphide polishing slurry can be black damping cloth.

[0094] The method for preparing the indium phosphide polishing solution provided in the embodiments of the present invention also includes other beneficial effects of the indium phosphide polishing solution provided in the embodiments of the present invention, which will not be elaborated here.

[0095] In the description of this specification, the references to terms such as "some embodiments," "in one example," and "exemplarily" indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0096] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0097] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are optional and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An indium phosphide polishing liquid characterized by comprising: The indium phosphide polishing solution includes abrasives, suspending agents, dispersants, a first oxidant, a second oxidant, surfactants, acid-base adjusters, photocatalysts, and solvents. The abrasive is alumina with a particle size range of 30nm-100nm, the solvent includes water, and the photocatalyst is configured to oxidize hydroxide and water molecules into hydroxyl radicals under light irradiation.

2. The indium phosphide polishing solution of claim 1, wherein The indium phosphide polishing slurry comprises the following components in weight percentage: abrasive: 5%-30%, suspending agent: 0.2%-3%, dispersant: 0.1%-2%, primary oxidant: 1%-10%, secondary oxidant: 0.2%-5%, surfactant: 0.2%-3%, acid-base adjuster: 0.1%-2%, and photocatalyst: 0.1%-2%.

3. The indium phosphide polishing solution of claim 1, wherein The photocatalyst includes at least one of titanium oxide, zirconium oxide, zinc oxide, ferric oxide, tin oxide, and zinc sulfide.

4. The indium phosphide polishing solution of claim 1, wherein The suspending agent includes at least one of inorganic bentonite, organic bentonite, magnesium aluminum silicate, sodium carboxymethyl cellulose, xanthan gum, lithium magnesium silicate, and carbomer.

5. The indium phosphide polishing solution of claim 1, wherein The dispersant includes at least one of aqueous sodium polyacrylate, sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium hypophosphite, sodium silicate, aluminum nitrate, and polyethylene glycol.

6. The indium phosphide polishing solution of claim 1, wherein The first oxidant is used to produce an oxide layer on the surface of indium phosphide, and includes at least one of sodium hypochlorite, sodium chlorate, sodium perchlorate, potassium perchlorate, and hydrogen peroxide.

7. The indium phosphide polishing solution of claim 1, wherein The second oxidant is used to provide a stable oxidizing atmosphere for the polishing slurry and to enhance the oxidizing activity of the first oxidant. It includes at least one of potassium nitrate, sodium nitrate, potassium dichromate, aluminum nitrate, sodium orthovanadate, sodium metavanadate, and potassium permanganate.

8. The indium phosphide polishing slurry according to claim 1, characterized in that, The surfactant includes at least one of nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sodium dodecyl sulfate, sodium fatty acid methyl ester sulfonate, and dodecyl sulfonic acid.

9. The indium phosphide polishing solution according to claim 1, characterized in that, The acid-base regulator includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, diethanolamine, potassium formate, and tetrasodium ethylenediaminetetraacetate.

10. A method for preparing an indium phosphide polishing solution, characterized in that, The method includes the following steps: (1) Add a dispersant to the first solvent and stir, then add alumina powder with a particle size range of 30nm-100nm, keep stirring and turn on ultrasonic dispersion to obtain the first solution; (2) Add a suspending agent to the second solvent and stir to obtain a second solution, wherein both the first solvent and the second solvent are water; (3) Add the second solution to the first solution and stir, turn on the sonication and keep stirring to obtain the third solution; (4) While stirring and sonicating, add the first oxidant, the second oxidant, the photocatalyst and the surfactant to the third solution in sequence to obtain the fourth solution; (5) Add acid-base adjuster to the fourth solution to adjust the acid-base value to the target range and obtain indium phosphide polishing solution.

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