Alkaline polishing solution for indium phosphide substrate, polishing method and indium phosphide polished wafer
By using silane coupling agent-modified nano-cerium oxide abrasive and an alkaline polishing slurry composed of an oxidant, combined with dynamic adjustment of polishing pressure and rotation speed, the problem of poor polishing effect of indium phosphide substrate was solved, achieving polished wafers with high flatness and low roughness, and increasing the effective chip count.
Patent Information
- Application Number
- CN202511778858.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-02-24
AI Technical Summary
In existing technologies, the polishing effect of indium phosphide substrates is poor, resulting in insufficient surface roughness and flatness, which makes it difficult to meet the performance requirements of high-end devices.
An alkaline polishing slurry composed of nano-cerium oxide abrasive modified with silane coupling agent, oxidant, and complexing agent, combined with a method of dynamically adjusting polishing pressure and rotation speed, achieves moderate oxidation and uniform polishing.
It improves the polishing effect of indium phosphide substrate, reduces surface roughness, enhances in-plane uniformity and flatness, and increases the effective chip count.
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Figure CN121555087A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of semiconductor material polishing technology, and particularly relates to an alkaline polishing solution and polishing method for an indium phosphide substrate, and an indium phosphide polishing sheet. Background Technology
[0002] Indium phosphide, as a core representative of second-generation semiconductor materials, is an irreplaceable substrate material for manufacturing high-speed optical fiber communication networks, millimeter-wave radio frequency front-end modules, and high-performance optoelectronic integrated chips due to its superior electron mobility, saturation drift velocity, and direct bandgap characteristics.
[0003] Traditional indium phosphide substrates are mainly 2-inch, 3-inch, and 4-inch, primarily used in low- to mid-range optical communication devices, detectors, or some radio frequency devices. With the large-scale commercialization of 5G mobile communication technology, the explosive growth of data center traffic, and the future evolution of terabit communication technology, the market demand for high-end indium phosphide-based devices (such as optical modulators, coherent receivers, and high electron mobility transistors with speeds of 100G / 400G and above) is becoming increasingly urgent, placing higher demands on their performance, power consumption, and cost. To reduce costs and increase production capacity, the industry is driving the transition of indium phosphide substrates from 2 / 3-inch to 4 / 6-inch. However, the increased size poses a severe challenge to the final surface polishing process.
[0004] After obtaining a single crystal ingot through single crystal growth and slicing it to obtain an indium phosphide substrate, the indium phosphide substrate needs to be ground and polished sequentially. Polishing is a technology that combines chemical etching and mechanical grinding to achieve ultra-precision surface planarization. Through the synergistic effect of mechanical and chemical processes, the wafer surface is planarized with atomic-level precision. The chemical polishing solution and polishing process used in the polishing process will affect the roughness and flatness of the indium phosphide substrate after polishing. Therefore, it is necessary to improve the polishing stage of the indium phosphide substrate to improve the polishing effect, thereby improving the quality of the indium phosphide substrate after polishing and significantly increasing the effective chip count. Summary of the Invention
[0005] In view of this, this application provides an alkaline polishing solution and polishing method for indium phosphide substrates, as well as an indium phosphide polishing sheet, to solve the technical problem of poor polishing effect of indium phosphide substrates in the prior art.
[0006] The first aspect of this application provides an alkaline polishing solution for an indium phosphide substrate, comprising silane coupling agent modified nano-cerium oxide abrasive, an oxidant, a complexing agent, and a deionized water solvent;
[0007] The pH of the alkaline polishing solution for the indium phosphide substrate is 7.5~9.0.
[0008] Preferably, the silane coupling agent modified cerium oxide nano-abrasive is selected from γ-aminopropyltriethoxysilane modified cerium oxide nano-abrasive and / or γ-aminopropyltrimethoxysilane modified cerium oxide nano-abrasive.
[0009] Preferably, the particle size of the silane coupling agent modified nano-cerium oxide abrasive is 30~80nm.
[0010] Preferably, the oxidant is selected from at least one of hydrogen peroxide, sodium hypochlorite, peracetic acid, sodium percarbonate, ammonium persulfate, sodium perborate, ferric nitrate, potassium iodate, aluminum trichloride, potassium permanganate, hypobromic acid, and hypoiodic acid.
[0011] Preferably, the complexing agent is selected from at least one of oxalic acid, citric acid, aminotriacetic acid, benzotriazole, benzimidazole, benzothiazole, ethylenediaminetetraacetic acid and its salts, diethylenetriaminepentaacetic acid and its salts, malic acid and its salts, tartaric acid and its salts, succinic acid and its salts, malonic acid and its salts, succinic acid and its salts, sodium tripolyphosphate, dihydroxyethylglycine, and tetrasodium iminodisuccinate.
[0012] Preferably, the alkaline pH adjuster used in the alkaline polishing solution for the indium phosphide substrate is at least one of potassium hydroxide, sodium hydroxide, ammonia, and tetramethylammonium hydroxide.
[0013] Preferably, the alkaline polishing solution for the indium phosphide substrate comprises, by weight, 1-5 parts by weight of silane coupling agent modified nano-cerium oxide abrasive, 0.3-0.5 parts by weight of oxidant, 0.05-0.15 parts by weight of complexing agent, and 80-120 parts by weight of deionized water solvent.
[0014] Preferably, the alkaline polishing solution for the indium phosphide substrate comprises, by weight, 3 parts by weight of silane coupling agent modified nano-cerium oxide abrasive, 0.44 parts by weight of oxidant, 0.1 parts by weight of complexing agent and 100 parts by weight of deionized water solvent.
[0015] The second aspect of this application provides a method for preparing an alkaline polishing solution for an indium phosphide substrate, which can prepare the alkaline polishing solution for an indium phosphide substrate described in the first aspect, comprising the following steps:
[0016] Under a nitrogen atmosphere, nano-cerium oxide abrasive was dispersed in an ethanol solution and hydrolyzed by adding a silane coupling agent and an alkaline pH adjuster. After post-treatment, nano-cerium oxide abrasive modified by silane coupling agent was obtained.
[0017] A silane coupling agent-modified nano-cerium oxide abrasive, oxidant, complexing agent, and deionized water solvent were mixed evenly, and the pH was adjusted to 7.5~9.0 using an alkaline pH adjuster to obtain an alkaline polishing solution for indium phosphide substrates.
[0018] Preferably, the post-processing includes: centrifugation, washing, and drying in sequence.
[0019] The third aspect of this application provides a polishing method for an indium phosphide substrate, which uses an alkaline polishing solution for the indium phosphide substrate described in the first aspect for polishing, and includes the following steps:
[0020] A 6-inch indium phosphide substrate is fixed by the polishing head of a polishing machine, and an alkaline polishing solution of an indium phosphide substrate as described in the first aspect is injected to perform rough polishing, semi-fine polishing, and fine polishing in sequence to obtain a 6-inch indium phosphide polished sheet.
[0021] During the rough polishing process, the polishing head of the polishing machine applies a pressure of 60 kg, rotates at 55 rpm, the polishing disc rotates at 60 rpm, and the rough polishing time is 10 min.
[0022] During the semi-finish polishing process, the polishing head of the polishing machine applied an initial pressure of 60 kg, which was linearly reduced to 40 kg at a rate of 4 kg / min. The initial rotation speed was 55 rpm, which was linearly reduced to 40 rpm at a rate of 3 rpm / min. The initial rotation speed of the polishing disc was 60 rpm, which was linearly reduced to 45 rpm at a rate of 3 rpm / min. The semi-finish polishing time was 5 min.
[0023] During the fine polishing process, the polishing head of the polishing machine applies a pressure of 20 kg, a rotation speed of 35 rpm, a polishing disc rotation speed of 40 rpm, and a time of 5 min.
[0024] The fourth aspect of this application provides a 6-inch indium phosphide polished wafer, which is obtained by the polishing method described in the third aspect.
[0025] Compared with the prior art, the present application provides an alkaline polishing solution and polishing method for indium phosphide substrates, and an indium phosphide polished wafer, which have at least the following beneficial effects:
[0026] 1. This application provides an alkaline polishing slurry for indium phosphide substrates. By using an alkaline polishing slurry with a specific pH, a moderate oxidation rate is achieved while avoiding excessive corrosion. Simultaneously, nano-cerium oxide abrasives are used to achieve "soft abrasive" chemical removal, reducing mechanical ploughing damage to the indium phosphide substrate. Furthermore, the nano-cerium oxide is modified with a silane coupling agent to provide dispersibility, reducing the varying depths and sizes of damage and scratches caused by the abrasives to the indium phosphide substrate. Thus, the alkaline polishing slurry provided in this application improves the roughness and flatness of the polished sheet obtained from polishing the indium phosphide substrate through compositional improvements, thereby enhancing the polishing effect.
[0027] 2. This application provides a polishing method for indium phosphide substrates. While polishing with the alkaline polishing solution, the applied pressure and rotation speed are dynamically adjusted. The pressure and rotation speed decrease linearly during the semi-finish polishing process, which compensates for the edge effect in the polishing of 6-inch indium phosphide substrates, thereby improving in-plane uniformity and making the roughness of the edge and center the same, thus improving the polishing effect.
[0028] 3. This application provides a polishing method for indium phosphide substrates, which significantly increases the effective chip count of the indium phosphide polished wafer due to improved in-plane uniformity. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0030] Figure 1 This is a schematic flowchart of a polishing method for a 6-inch indium phosphide substrate provided in Example 1. Detailed Implementation
[0031] This application provides an alkaline polishing solution and polishing method for indium phosphide substrates, as well as an indium phosphide polishing sheet, to solve the technical problem of poor polishing effect of indium phosphide substrates in the prior art.
[0032] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0033] In view of the current defects of poor polishing effect of indium phosphide substrates, this application provides an alkaline polishing solution and polishing method for indium phosphide substrates; the alkaline polishing solution for indium phosphide substrates provided has a pH of 7.5~9.0 and is composed of nano-cerium oxide abrasive, oxidant, complexing agent and deionized water solvent.
[0034] In the alkaline polishing solution for indium phosphide substrates provided in this application, the oxidant used, such as hydrogen peroxide, is a mild oxidant that can gently form a loose and easily removable oxide layer of In₂O₃, P₂O₅, etc., on the surface of the indium phosphide substrate. The alkaline environment with a pH of 7.5~9.0 ensures a moderate oxidation rate while avoiding excessive corrosion of the indium phosphide substrate. Furthermore, the surface of the nano-cerium oxide particles is rich in Ce.3+ / Ce 4+ Ion pairs have a strong ability to adsorb oxygen, effectively adsorbing and activating water molecules or oxygen in the environment, converting them into highly reactive oxygen species such as hydroxyl radicals. These reactive oxygen species catalyze the oxidation reaction on the surface of indium phosphide substrates, accelerating the oxidation of indium and phosphorus atoms, resulting in a very soft and porous oxide layer. This allows for "soft abrasive" chemical removal rather than mechanical ploughing. Furthermore, the complexing agent effectively complexes the removed indium ions, preventing their redeposition onto the substrate surface and the formation of defects. Therefore, the alkaline indium phosphide substrate polishing solution used in this application, comprising nano-cerium oxide abrasive, oxidant, complexing agent, and deionized water solvent, can achieve polishing. And those skilled in the art know... The Mohs hardness of indium phosphide substrates is around 4.5, which is much lower than that of silicon carbide substrates (around 9.5). For indium phosphide substrates with lower hardness, the agglomeration of nanoscale abrasives in chemical polishing solutions, resulting in abrasives with a wide particle size distribution, can easily cause damage and scratches of varying depths and sizes to the indium phosphide substrate. This makes the surface of the indium phosphide substrate prone to microscopic unevenness, increasing roughness and reducing the polishing effect. This application provides a surface modification of nano-cerium oxide abrasives to improve dispersibility. Using nano-cerium oxide modified with a silane coupling agent with good dispersibility as the abrasive improves the polishing effect, thereby solving the technical problem of poor polishing effect of indium phosphide substrates.
[0035] Meanwhile, the polishing method for an indium phosphide substrate provided in this application uses the aforementioned alkaline polishing solution for polishing. The polishing process is divided into rough polishing, semi-fine polishing, and fine polishing. The purpose of the rough polishing process is to quickly remove the damaged layer left by the previous grinding process and achieve preliminary global planarization. In the semi-fine polishing process, the applied pressure and rotation speed are dynamically adjusted. The pressure and rotation speed decrease linearly during the semi-fine polishing process, which effectively compensates for the edge effect in the polishing of the 6-inch indium phosphide substrate, thereby improving the in-plane uniformity. The roughness of the edge and center of the 6-inch indium phosphide polished sheet is uniform, and there will be no unevenness in the roughness of the edge and center, thus improving the polishing effect. In the fine polishing process, through slight chemical action and mechanical friction, micro-scratches are completely eliminated to obtain an atomically smooth surface, thereby obtaining an indium phosphide polished sheet with high flatness and low roughness.
[0036] Example 1
[0037] This embodiment provides a polishing method for a 6-inch indium phosphide substrate, as shown in the flowchart below. Figure 1 As shown, the process includes the steps of preparing an alkaline polishing solution and the polishing process.
[0038] The steps for preparing an alkaline polishing solution include:
[0039] 500g of cerium oxide nanoparticles with an average particle size of 50nm and an ethanol solution were added to a reaction vessel and dispersed evenly. Then, 100g of silane coupling agent KH-550 and an appropriate amount of ammonia were added to hydrolyze the silane coupling agent KH-550. After reacting for 3 hours, silane coupling agent modified cerium oxide nanoparticles were obtained. Next, they were centrifuged and washed alternately with ethanol and deionized water, and dried for later use.
[0040] Mix 10L of deionized water, 300g of silane coupling agent modified nano-cerium oxide abrasive, 40mL of hydrogen peroxide solution (30wt%) and 10g of citric acid evenly, and add an appropriate amount of tetramethylammonium hydroxide aqueous solution to adjust the pH to 8.5 to obtain an alkaline polishing solution for indium phosphide substrate for later use.
[0041] The polishing steps include:
[0042] Prepare 5 6-inch indium phosphide (InP-S) substrates with an average roughness Ra > 2 nm after grinding.
[0043] A 6-inch indium phosphide substrate was fixed in place using the polishing head of a polishing machine, and the alkaline polishing solution of the indium phosphide substrate prepared in this embodiment was injected sequentially for polishing, resulting in a thickness drop of 30 μm.
[0044] The rough polishing process in polishing is as follows: apply a pressure of 60 kg, control the speed of the carrier to 55 rpm, and the speed of the polishing disc to 60 rpm for rough polishing for 10 minutes;
[0045] The semi-finish polishing process is as follows: apply an initial pressure of 60 kg and linearly decrease it to 40 kg at a speed of 4 kg / min, control the initial rotation speed of the carrier to 55 rpm and linearly decrease it to 40 rpm at a speed of 3 rpm / min, the initial rotation speed of the polishing disc to 60 rpm and linearly decrease it to 45 rpm at a speed of 3 rpm / min, and the semi-finish polishing time is 5 min.
[0046] The fine polishing process in polishing is as follows: apply a pressure of 20 kg, control the speed of the carrier to 35 rpm, and the speed of the polishing disc to 40 rpm for 5 minutes of fine polishing;
[0047] Five 6-inch indium phosphide substrates were sequentially rough-polished, semi-fine-polished, and fine-polished to obtain five 6-inch indium phosphide polished wafers for later use.
[0048] Example 2
[0049] This embodiment provides a polishing method for a 6-inch indium phosphide substrate. As the first comparative example of Example 1, the difference from Example 1 is that nano-silica is used as the abrasive, and the method includes the steps of preparing an alkaline polishing solution and polishing.
[0050] The steps for preparing an alkaline polishing solution include:
[0051] Mix 10L of deionized water, 300g of nano-silica abrasive, 40mL of hydrogen peroxide solution (30wt%) and 10g of citric acid evenly, and add an appropriate amount of tetramethylammonium hydroxide aqueous solution to adjust the pH to 8.5 to obtain an alkaline polishing solution for indium phosphide substrate for later use.
[0052] The polishing steps include:
[0053] Prepare 5 6-inch indium phosphide (InP-S) substrates with an average roughness Ra > 2 nm after grinding.
[0054] A 6-inch indium phosphide substrate was fixed in place using the polishing head of a polishing machine, and the alkaline polishing solution of the indium phosphide substrate prepared in this embodiment was injected sequentially for polishing, resulting in a thickness drop of 14 μm.
[0055] The rough polishing process in polishing is as follows: apply a pressure of 60 kg, control the speed of the carrier to 55 rpm, and the speed of the polishing disc to 60 rpm for rough polishing for 10 minutes;
[0056] The semi-finish polishing process is as follows: apply an initial pressure of 60 kg and linearly decrease it to 40 kg at a speed of 4 kg / min, control the initial rotation speed of the carrier to 55 rpm and linearly decrease it to 40 rpm at a speed of 3 rpm / min, the initial rotation speed of the polishing disc to 60 rpm and linearly decrease it to 45 rpm at a speed of 3 rpm / min, and the semi-finish polishing time is 5 min.
[0057] The fine polishing process in polishing is as follows: apply a pressure of 20 kg, control the speed of the carrier to 35 rpm, and the speed of the polishing disc to 40 rpm for 5 minutes of fine polishing;
[0058] Five 6-inch indium phosphide substrates were sequentially rough-polished, semi-fine-polished, and fine-polished to obtain five 6-inch indium phosphide polished wafers for later use.
[0059] Example 3
[0060] This embodiment provides a polishing method for a 6-inch indium phosphide substrate. As a second comparative example of Example 1, the difference from Example 1 is that nano-cerium oxide is used as the abrasive, and the method includes the steps of preparing an alkaline polishing solution and polishing.
[0061] The steps for preparing an alkaline polishing solution include:
[0062] Mix 10L of deionized water, 300g of nano-cerium oxide abrasive, 40mL of hydrogen peroxide solution (30wt%) and 10g of citric acid evenly, and add an appropriate amount of tetramethylammonium hydroxide aqueous solution to adjust the pH to 8.5 to obtain an alkaline polishing solution for indium phosphide substrate for later use.
[0063] The polishing steps include:
[0064] Prepare 5 6-inch indium phosphide (InP-S) substrates with an average roughness Ra > 2 nm after grinding.
[0065] A 6-inch indium phosphide substrate was fixed in place using the polishing head of a polishing machine, and the alkaline polishing solution of the indium phosphide substrate prepared in this embodiment was injected sequentially for polishing, resulting in a thickness drop of 30 μm.
[0066] The rough polishing process in polishing is as follows: apply a pressure of 60 kg, control the speed of the carrier to 55 rpm, and the speed of the polishing disc to 60 rpm for rough polishing for 10 minutes;
[0067] The semi-finish polishing process is as follows: apply an initial pressure of 60 kg and linearly decrease it to 40 kg at a speed of 4 kg / min, control the initial rotation speed of the carrier to 55 rpm and linearly decrease it to 40 rpm at a speed of 3 rpm / min, the initial rotation speed of the polishing disc to 60 rpm and linearly decrease it to 45 rpm at a speed of 3 rpm / min, and the semi-finish polishing time is 5 min.
[0068] The fine polishing process in polishing is as follows: apply a pressure of 20 kg, control the speed of the carrier to 35 rpm, and the speed of the polishing disc to 40 rpm for 5 minutes of fine polishing;
[0069] Five 6-inch indium phosphide substrates were sequentially rough-polished, semi-fine-polished, and fine-polished to obtain five 6-inch indium phosphide polished wafers for later use.
[0070] Example 4
[0071] This embodiment provides a polishing method for a 6-inch indium phosphide substrate. As the third comparative example of Example 1, the difference from Example 1 is that an acidic pH polishing solution is used for polishing, including the steps of preparing the acidic polishing solution and the polishing step.
[0072] The steps for preparing an acidic polishing solution include:
[0073] 500g of cerium oxide nanoparticles with an average particle size of 50nm and an ethanol solution were added to a reaction vessel and dispersed evenly. Then, 100g of silane coupling agent KH-550 and an appropriate amount of ammonia were added to hydrolyze the silane coupling agent KH-550. After reacting for 3 hours, silane coupling agent modified cerium oxide nanoparticles were obtained. Next, they were centrifuged and washed alternately with ethanol and deionized water, and dried for later use.
[0074] Mix 10L of deionized water, 300g of silane coupling agent modified nano-cerium oxide abrasive, 40mL of hydrogen peroxide solution (30wt%) and 10g of citric acid evenly to obtain an acidic polishing solution for indium phosphide substrate.
[0075] The polishing steps include:
[0076] Prepare 5 6-inch indium phosphide (InP-S) substrates with an average roughness Ra > 2 nm after grinding.
[0077] A 6-inch indium phosphide substrate was fixed in place using the polishing head of a polishing machine, and the indium phosphide substrate prepared in this embodiment was injected sequentially for polishing, resulting in a thickness drop of 30 μm.
[0078] The rough polishing process in polishing is as follows: apply a pressure of 60 kg, control the speed of the carrier to 55 rpm, and the speed of the polishing disc to 60 rpm for rough polishing for 10 minutes;
[0079] The semi-finish polishing process is as follows: apply an initial pressure of 60 kg and linearly decrease it to 40 kg at a speed of 4 kg / min, control the initial rotation speed of the carrier to 55 rpm and linearly decrease it to 40 rpm at a speed of 3 rpm / min, the initial rotation speed of the polishing disc to 60 rpm and linearly decrease it to 45 rpm at a speed of 3 rpm / min, and the semi-finish polishing time is 5 min.
[0080] The fine polishing process in polishing is as follows: apply a pressure of 20 kg, control the speed of the carrier to 35 rpm, and the speed of the polishing disc to 40 rpm for 5 minutes of fine polishing;
[0081] Five 6-inch indium phosphide substrates were sequentially rough-polished, semi-fine-polished, and fine-polished to obtain five 6-inch indium phosphide polished wafers for later use.
[0082] Example 5
[0083] This embodiment provides a polishing method for a 6-inch indium phosphide substrate. As the third comparative example of Example 1, the difference from Example 1 is that the pressure and rotation speed are not adjusted during the polishing process, and the method includes the steps of preparing alkaline polishing solution and polishing.
[0084] The steps for preparing an alkaline polishing solution include:
[0085] 500g of cerium oxide nanoparticles with an average particle size of 50nm and an ethanol solution were added to a reaction vessel and dispersed evenly. Then, 100g of silane coupling agent KH-550 and an appropriate amount of ammonia were added to hydrolyze the silane coupling agent KH-550. After reacting for 3 hours, silane coupling agent modified cerium oxide nanoparticles were obtained. Next, they were centrifuged and washed alternately with ethanol and deionized water, and dried for later use.
[0086] Mix 10L of deionized water, 300g of silane coupling agent modified nano-cerium oxide abrasive, 40mL of hydrogen peroxide solution (30wt%) and 10g of citric acid evenly, and add an appropriate amount of tetramethylammonium hydroxide aqueous solution to adjust the pH to 8.5 to obtain an alkaline polishing solution for indium phosphide substrate for later use.
[0087] The polishing steps include:
[0088] Prepare 5 6-inch indium phosphide (InP-S) substrates with an average roughness Ra > 2 nm after grinding.
[0089] A 6-inch indium phosphide substrate was fixed in place using the polishing head of a polishing machine, and the alkaline polishing solution of the indium phosphide substrate prepared in this embodiment was injected sequentially for polishing, resulting in a thickness drop of 30 μm.
[0090] The rough polishing process in polishing is as follows: apply a pressure of 60 kg, control the speed of the carrier to 55 rpm, and the speed of the polishing disc to 60 rpm for rough polishing for 10 minutes;
[0091] The semi-finish polishing process in polishing is as follows: apply a pressure of 40 kg, control the speed of the carrier to 40 rpm, and the speed of the polishing disc to 45 rpm for 5 minutes of semi-finish polishing;
[0092] The fine polishing process in polishing is as follows: apply a pressure of 20 kg, control the speed of the carrier to 35 rpm, and the speed of the polishing disc to 40 rpm for 5 minutes of fine polishing;
[0093] Five 6-inch indium phosphide substrates were sequentially rough-polished, semi-fine-polished, and fine-polished to obtain five 6-inch indium phosphide polished wafers for later use.
[0094] Experimental Example 1
[0095] In this experiment, the 6-inch indium phosphide polished wafers provided in Examples 1-5 were tested for overall surface flatness (TTV) using a flatness meter, and for surface roughness (Ra) at the edges and center using an atomic force microscope to characterize the polishing effect; the test results are shown in Table 1.
[0096] Table 1: Polishing effect test results
[0097]
[0098] As shown in Table 1, the polishing effect test results indicate that the polishing methods provided in Examples 1-5 all reduced the roughness of the abrasive disc, but there were differences in the flatness and roughness of the polished disc. In Example 2, the polishing fluid used in the polishing stage contained nano-silica as the abrasive. The nano-silica abrasive surface does not contain Ce, which adsorbs oxygen. 3+ / Ce 4+Ion pairs cannot convert active oxygen to catalyze the oxidation reaction on the surface of indium phosphide substrate, so polishing mainly relies on mechanical ploughing action. Moreover, the high hardness of nano-silica makes it easy to damage the indium phosphide polishing sheet during the polishing process, resulting in a decrease in flatness and roughness. It can be seen that compared with Example 2, the polishing sheet provided in Example 1 has improved the polishing effect by adding softer nano-cerium oxide abrasive to the polishing liquid used in the polishing stage.
[0099] The polishing effect test results shown in Table 1 also show that the polishing sheet provided in Example 3 uses nano-cerium oxide as the abrasive in the polishing slurry during the polishing stage, but it is not modified with a surface silane coupling agent, resulting in poor dispersibility. The nano-cerium oxide abrasive is prone to agglomeration, forming abrasive particles of varying sizes, which can easily cause damage and scratches of varying depths and sizes to the indium phosphide substrate, making the surface of the indium phosphide substrate prone to microscopic unevenness and increased roughness. It can be seen that compared with Example 3, the polishing sheet provided in Example 1, by adding silane-modified nano-cerium oxide abrasive to the polishing slurry during the polishing stage, improves the dispersibility and polishing effect.
[0100] The polishing effect test results shown in Table 1 also show that the polishing solution used in the polishing stage of the polishing sheet provided in Example 4 is an acidic pH polishing solution. Unlike alkaline pH polishing solutions, it cannot guarantee a moderate oxidation rate while avoiding excessive corrosion of the indium phosphide substrate. As a result, the substrate is corroded faster during the polishing process, making it difficult to control the corrosion rate. Some areas of the polishing sheet are corroded more deeply, while others are corroded less deeply, which reduces the flatness of the polishing sheet. It can be seen that compared with Example 4, the polishing sheet provided in Example 1 uses an alkaline polishing solution in the polishing stage, which gently controls corrosion and oxidation and improves the polishing effect.
[0101] The polishing effect test results shown in Table 1 also show that the polishing sheet provided in Example 5 did not control the pressure and rotation speed during the polishing stage, and could not compensate for the edge effect in the polishing of large-size indium phosphide substrates, resulting in different roughness between the edge and the center, and uneven roughness. It can be seen that compared with Example 5, the polishing sheet provided in Example 1 used dynamic control of the applied pressure and rotation speed during the polishing stage, compensated for the edge effect, improved the polishing effect, and increased the effective chip load of the polishing sheet provided in Example 1.
[0102] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. An alkaline polishing solution for an indium phosphide substrate, characterized in that, include: Silane coupling agent modified nano-cerium oxide abrasive, oxidant, complexing agent and deionized water solvent; The pH of the alkaline polishing solution for the indium phosphide substrate is 7.5~9.
0.
2. The alkaline polishing solution for an indium phosphide substrate according to claim 1, characterized in that, The silane coupling agent modified nano-cerium oxide abrasive is selected from γ-aminopropyltriethoxysilane modified nano-cerium oxide abrasive and / or γ-aminopropyltrimethoxysilane modified nano-cerium oxide abrasive.
3. The alkaline polishing solution for an indium phosphide substrate according to claim 1, characterized in that, The particle size of the silane coupling agent modified nano-cerium oxide abrasive is 30~80nm.
4. The alkaline polishing solution for an indium phosphide substrate according to claim 1, characterized in that, The oxidant is selected from at least one of hydrogen peroxide, sodium hypochlorite, peracetic acid, sodium percarbonate, ammonium persulfate, sodium perborate, ferric nitrate, potassium iodate, aluminum trichloride, potassium permanganate, hypobromic acid, and hypoiodic acid.
5. The alkaline polishing solution for an indium phosphide substrate according to claim 1, characterized in that, The complexing agent is selected from at least one of oxalic acid, citric acid, aminotriacetic acid, benzotriazole, benzimidazole, benzothiazole, ethylenediaminetetraacetic acid and its salts, diethylenetriaminepentaacetic acid and its salts, malic acid and its salts, tartaric acid and its salts, succinic acid and its salts, malonic acid and its salts, succinic acid and its salts, sodium tripolyphosphate, dihydroxyethylglycine, and tetrasodium iminodisuccinate.
6. The alkaline polishing solution for an indium phosphide substrate according to claim 1, characterized in that, The alkaline pH adjuster used in the alkaline polishing solution for the indium phosphide substrate is at least one of potassium hydroxide, sodium hydroxide, ammonia, and tetramethylammonium hydroxide.
7. The alkaline polishing solution for an indium phosphide substrate according to claim 1, characterized in that, The alkaline polishing solution for the indium phosphide substrate comprises, by weight, 3 parts by weight of silane coupling agent modified nano-cerium oxide abrasive, 0.44 parts by weight of oxidant, 0.1 parts by weight of complexing agent and 100 parts by weight of deionized water solvent.
8. A method for preparing an alkaline polishing solution for an indium phosphide substrate, characterized in that, An alkaline polishing solution for an indium phosphide substrate as described in any one of claims 1-7 can be prepared by the following steps: Under a nitrogen atmosphere, nano-cerium oxide abrasive was dispersed in an ethanol solution and hydrolyzed by adding a silane coupling agent and an alkaline pH adjuster. After post-treatment, nano-cerium oxide abrasive modified by silane coupling agent was obtained. A silane coupling agent-modified nano-cerium oxide abrasive, oxidant, complexing agent, and deionized water solvent were mixed evenly, and the pH was adjusted to 7.5~9.0 using an alkaline pH adjuster to obtain an alkaline polishing solution for indium phosphide substrates.
9. A polishing method for an indium phosphide substrate, characterized in that, Includes the following steps: A 6-inch indium phosphide substrate is fixed by the polishing head of a polishing machine, and an alkaline polishing solution of an indium phosphide substrate as described in any one of claims 1-7 is injected to perform rough polishing, semi-fine polishing, and fine polishing in sequence to obtain a 6-inch indium phosphide polished sheet. During the rough polishing process, the polishing head of the polishing machine applies a pressure of 60 kg, rotates at 55 rpm, the polishing disc rotates at 60 rpm, and the rough polishing time is 10 min. During the semi-finish polishing process, the polishing head of the polishing machine applied an initial pressure of 60 kg, which was linearly reduced to 40 kg at a rate of 4 kg / min. The initial rotation speed was 55 rpm, which was linearly reduced to 40 rpm at a rate of 3 rpm / min. The initial rotation speed of the polishing disc was 60 rpm, which was linearly reduced to 45 rpm at a rate of 3 rpm / min. The semi-finish polishing time was 5 min. During the fine polishing process, the polishing head of the polishing machine applies a pressure of 20 kg, a rotation speed of 35 rpm, a polishing disc rotation speed of 40 rpm, and a time of 5 min.
10. A 6-inch indium phosphide polished wafer, characterized in that, It is obtained by polishing by the polishing method described in claim 9.