Sodium dichloroisocyanurate composite polishing solution for improving indium phosphide removal rate and surface quality

Abstract

The invention relates to a sodium dichloroisocyanurate composite polishing solution capable of improving indium phosphide removal rate and surface quality. The polishing solution is prepared from the following components: nano silicon dioxide with the concentration of 8.0 to 12.0 weight percent, an oxidant with the concentration of 0.8 to 1.1 weight percent, a complexing agent with the concentration of 0.8 to 1.1 weight percent, a surfactant with the concentration of 200 to 500 ppm and the balance of deionized water, and the pH value of the polishing solution system is 8.9-9.1. The oxidizing agent is sodium dichloroisocyanurate; the complexing agent is potassium sorbate; according to the polishing solution, the removal rate and the surface quality of indium phosphide are obviously improved, and harmful gas is not generated to the maximum extent under the alkaline condition.

Description

Technical Field

[0001] This invention belongs to the field of chemical mechanical polishing, specifically relating to a green and environmentally friendly composite abrasive chemical mechanical polishing slurry that can achieve a high removal rate and low surface roughness for indium phosphide. Background Technology

[0002] Indium phosphide (InP) is an important semiconductor material, showing great potential, especially in high-speed electronic devices, optical communications, optoelectronic devices, quantum technology, and high-power applications. With technological advancements and increasing application demands, InP research not only drives the development of semiconductor materials but also provides fundamental support for the realization of many advanced technologies. InP exhibits higher electron mobility than silicon (Si) and gallium arsenide (GaAs), particularly in high-frequency applications where it offers faster electronic response speeds. As silicon-based semiconductors face performance bottlenecks in high-frequency, high-power, and high-temperature applications, InP has become an important alternative material. Furthermore, its inherently high photoelectric conversion efficiency can improve conversion efficiency and promote the development of green energy technologies.

[0003] Indium phosphide (InP) exhibits high chemical sensitivity, while alumina has high hardness and readily reacts chemically with InP surfaces, potentially causing surface damage or corrosion and affecting polishing results. Silica, as a base abrasive, possesses better chemical stability, is less prone to adverse reactions with InP, and allows for gentler polishing. The small and uniform particle size of silica contributes to a finer polishing effect and avoids scratches. Using silica as a polishing slurry better maintains the surface smoothness of InP during polishing. Silica polishing slurries provide a more uniform surface smoothness, reducing surface defects. Silica is widely used in the polishing of many semiconductor and optoelectronic materials, achieving a more uniform polishing effect. Silica also exhibits good thermal stability, maintaining its performance at high temperatures and minimizing thermal effects, which is crucial for fine polishing. In contrast, alumina may cause additional thermal damage or chemical changes at high temperatures.

[0004] During the production process, a layer of oxides and organic matter forms on the surface of InP, which can affect its performance and quality. Therefore, appropriate methods are needed to remove these contaminants to ensure the purity and performance of InP. Traditional methods for removing surface contaminants from InP include chemical cleaning, physical cleaning, and heat treatment. Chemical cleaning is one of the most commonly used methods, but the selection and concentration control of chemical cleaning agents are complex and can damage equipment. Furthermore, chemical cleaning agents may introduce new contaminants, affecting the quality of InP. A patent (CN114131434A - A Thinning Polishing Method for Indium Phosphide) uses NaClO as an oxidant and Al2O3 as an abrasive to prepare a single-component polishing solution. CMP is performed on InP at pH 12 with a polishing rate of 500 nm / min. The polishing effect is unsatisfactory, with scratches observed on the surface. The polishing rate is not significantly improved, and there are limitations such as the need to improve the surface quality of the polishing material. Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the shortcomings of current technologies by providing a highly efficient and stable composite polishing slurry that improves the removal rate and surface quality of indium phosphide (InP). This polishing slurry uses sodium dichloroisocyanurate as the oxidant, which offers better selectivity and safety compared to sodium hypochlorite, effectively removing oxides and organic matter from the InP surface. Furthermore, potassium sorbate is added as a complexing agent to bind with indium ions, forming a soluble complex and reducing the likelihood of corrosion on the InP surface. Finally, the surfactant octadecyltrimethylammonium chloride is added to reduce the coefficient of friction, providing lubrication and minimizing friction between silica particles and the material surface during polishing, thus preventing surface scratches or damage and improving the surface quality of the InP substrate. This invention's polishing slurry significantly improves both the removal rate and surface quality of InP, and is carried out under alkaline conditions, minimizing the generation of harmful gases. Therefore, using sodium dichloroisocyanurate as the oxidant to prepare the composite polishing slurry for polishing InP is a more ideal method.

[0006] To achieve the above objectives, the solution to the technical problem of this invention is as follows:

[0007] A sodium dichloroisocyanurate composite polishing slurry for improving the removal rate and surface quality of indium phosphide, the slurry comprising the following components: nano-silica concentration of 8.0–12.0 wt.%, oxidant concentration of 0.8–1.1 wt.%, complexing agent concentration of 0.8–1.1 wt.%, surfactant concentration of 200–500 ppm, with the balance being deionized water; the pH value of the polishing slurry system is 8.9–9.1.

[0008] The particle size of the nano-silica is 30-50 nm;

[0009] The oxidant is sodium dichloroisocyanurate, with a concentration of 0.8–1.1 wt.%.

[0010] The complexing agent is potassium sorbate, with a concentration of 0.8–1.1 wt.%.

[0011] The cationic surfactant is octadecyltrimethylammonium chloride (STAC) at a concentration of 200–500 ppm;

[0012] The pH adjuster is one or both of nitric acid (HNO3) and potassium hydroxide (KOH);

[0013] The preparation method of the high-efficiency polishing slurry using sodium dichloroisocyanurate composite abrasive to improve the removal rate and surface quality of indium phosphide includes the following steps:

[0014] Step S1: Add 35-45 wt.% of nano-SiO2 sol to a beaker, and slowly add deionized water to the beaker to dilute the nano-silica in the SiO2 sol to a concentration of 8.0-12.0 wt.%.

[0015] Step S2: Next, add sodium dichloroisocyanurate (oxidizing agent), potassium sorbate (complexing agent), and octadecyltrimethylammonium chloride (surfactant) to the solution obtained in step S1 in sequence.

[0016] Step S3: Add the remaining deionized water to the solution obtained in step S2 until the target volume is reached, and then place the beaker on a stirrer and stir for 4 to 6 minutes.

[0017] Step S4: Adjust the pH of the solution obtained in step S3 to the target pH using nitric acid (HNO3) and potassium hydroxide (KOH).

[0018] The composite abrasive polishing slurry used to improve the removal rate and surface quality of indium phosphide is used for chemical mechanical polishing of indium phosphide substrates.

[0019] The polishing machine used for polishing is a Rui Xuan SSP-500, and the polishing conditions are:

[0020] The polishing time is 310s (300s for liquid polishing and 10s for water polishing), the polishing pressure is 3.29psi (14kg), the polishing fluid flow rate is 80ml / min, the polishing head speed is 50rad / min, and the polishing disc speed is 50rad / min.

[0021] The essential features of this invention are:

[0022] This invention introduces sodium dichloroisocyanurate as the oxidant, potassium sorbate as the complexing agent, and octadecyltrimethylammonium chloride solution as the surfactant into an alkaline nano-SiO2 sol. By maintaining the pH of the polishing solution at 9, a stable sodium dichloroisocyanurate composite polishing solution is obtained. From an internal mechanism perspective, sodium dichloroisocyanurate can oxidize phosphorus on the surface of indium phosphide under alkaline conditions. The oxidation reaction destroys the oxide layer on the surface of indium phosphide, making the chemical bonds between phosphorus and indium easier to break. Subsequently, silica, through tiny particles, contacts the surface of indium phosphide, forming microscopic frictional forces that gradually remove the uneven parts of the indium phosphide surface. Simultaneously, octadecyltrimethylammonium chloride acts as a lubricant, decontaminant, and interfacial active agent. Its hydrophobic tail reduces the frictional resistance of the InP surface, minimizing scratches and corrosion during mechanical polishing, while also helping to disperse and stabilize silica particles, preventing their aggregation and precipitation. Furthermore, the surfactant enhances the oxidation effect of sodium dichloroisocyanurate, making it more uniformly distributed in the polishing solution.

[0023] Compared with the current technology, the beneficial effects of the present invention are:

[0024] This invention provides a composite abrasive polishing slurry using sodium dichloroisocyanurate as an oxidant, aiming to improve the removal rate and surface quality of indium phosphide. The polishing slurry has a pH of 9 and uses sodium dichloroisocyanurate as the oxidant, potassium sorbate as the complexing agent, and octadecyltrimethyl as the surfactant. Compared to the single polishing slurry formulated with only sodium hypochlorite as the oxidant and alumina as the abrasive in the patent of Sun Jinyang et al. (CN114131434A, involving a method for thinning and polishing indium phosphide), this invention uses a composite formulation of sodium dichloroisocyanurate, potassium sorbate, and octadecyltrimethyl, effectively improving the removal rate of indium phosphide to 1278.6 nm / min. The polishing rate is significantly improved, and the surface roughness is only 0.065 nm, resulting in significantly improved surface quality without scratches. Furthermore, this invention has lower cost and is environmentally friendly. Attached Figure Description

[0025] The invention will now be further described with reference to the accompanying drawings and examples. In the accompanying drawings:

[0026] Figure 1 A schematic diagram of the preparation process for a green and environmentally friendly sodium dichloroisocyanurate composite abrasive polishing slurry to improve the removal rate and surface quality of indium phosphide substrates.

[0027] Figure 2 The image shows the AFM microstructure of the polished indium phosphide substrate corresponding to Example 1. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and best examples. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] Please see Figure 1 This invention provides a green and environmentally friendly sodium dichloroisocyanurate composite abrasive polishing slurry to improve the removal rate and surface quality of indium phosphide substrates, comprising the following steps:

[0030] Step S1: Add 40 wt.% nano-SiO2 sol with a particle size of 40 nm to a beaker, and slowly add deionized water to the beaker to dilute the nano-silica in the SiO2 sol to a concentration of 10 wt.%.

[0031] Step S2: Next, add sodium dichloroisocyanurate (1 wt.%), potassium sorbate (1 wt.%), osmotic agent, and octadecyltrimethylammonium chloride (300 ppm) to the solution obtained in step S1 in sequence.

[0032] Step S3: Add the remaining deionized water to the solution obtained in step S2 until the target volume v3 is reached. Place the beaker on the stirrer and stir for t1. The purpose is to make the polishing solution components more evenly distributed and to stabilize the polishing solution components.

[0033] Step S4: Adjust to the target pH of 9 using HNO3 and KOH.

[0034] In step S1 of the present invention, the volume of the silicon dioxide is v1 125 ml, v2 375 ml, and v3 500 ml.

[0035] In step S2 of the present invention, the oxidant sodium dichloroisocyanurate m1 is 5g, the complexing agent potassium sorbate m2 is 5g, and the surfactant octadecyltrimethylammonium chloride solution m3 is 0.15g.

[0036] In step S3 of the present invention, the stirring time t1 is 5 min.

[0037] Example 1

[0038] Prepare 500ml of polishing liquid

[0039] Add 125 ml of 40 wt.% SiO2 sol with a particle size of 40 nm to a beaker. Then add 5 g of oxidant (sodium dichloroisocyanurate), 5 g of complexing agent (potassium sorbate), and 0.15 g of surfactant (octadecyltrimethylammonium chloride). Finally, add the remaining deionized water to the beaker until the target volume (500 ml) is reached. At this point, the concentration of nano-silica in the SiO2 sol is 10 wt.%. Place the beaker containing the polishing solution on a stirrer and stir for 5 minutes to make the components of the polishing solution more evenly dispersed. Then adjust the polishing solution to the target pH of 9 with HNO3 and KOH. Finally, 500 ml of polishing solution was successfully prepared.

[0040] The polishing machine used was a Rui Xuan SSP-500, and the polishing conditions were as follows: polishing time was 310s (300s for liquid polishing and 10s for water polishing), polishing pressure was 3.29psi, polishing fluid flow rate was 80ml / min, polishing head speed was 50rad / min, and polishing disc speed was 50rad / min.

[0041] The 3-inch indium phosphide substrate was chemically and mechanically polished. After polishing, it was rinsed with deionized water and brushed with a PVA brush to remove the polishing liquid particles remaining on the surface of the indium phosphide substrate. Finally, the residual moisture on the surface of the quartz wafer was dried with high-purity nitrogen.

[0042] Example 2

[0043] Prepare 500ml of polishing liquid

[0044] The other steps are the same as in Example 1, except that 2.5g of sodium dichloroisocyanurate is added;

[0045] Example 3

[0046] Prepare 500ml of polishing liquid

[0047] The other steps are the same as in Example 1, except that 7.5g of sodium dichloroisocyanurate is added;

[0048] Example 4

[0049] Prepare 500ml of polishing liquid

[0050] The other steps are the same as in Example 1, except that 2.5g of potassium sorbate is added;

[0051] Example 5

[0052] Prepare 500ml of polishing liquid

[0053] The other steps are the same as in Example 1, except that 7.5g of potassium sorbate is added;

[0054] Example 6

[0055] The other steps are the same as in Example 1, except that the surfactant is the cationic surfactant CTAC.

[0056] Example 7

[0057] The other steps are the same as in Example 1, except that the surfactant is the cationic surfactant DTAC.

[0058] Example 8

[0059] The other steps are the same as in Example 1, except that the surfactant is the cationic surfactant TDBAC.

[0060] Table 1 compares the removal rate and surface roughness of Examples 1-8.

[0061]

[0062] The reason for the low removal rate of indium phosphide in Examples 2-5 is that only when appropriate concentrations of sodium dichloroisocyanurate and sorbitan can be added, the interaction between sodium dichloroisocyanurate and the complexing agent potassium sorbate and the cationic surfactant octadecyltrimethylammonium chloride can be maximized, thus helping to control the surface reaction rate and protect the surface of indium phosphide from unnecessary damage.

[0063] The main reasons for the poor surface quality and low removal rate of indium phosphide in Examples 6-8 are as follows: STAC has strong interfacial activity, enabling it to effectively interact with other components in the polishing solution, such as sodium dichloroisocyanurate and silica. This interfacial activity and long hydrophobic chains help reduce surface energy, making the InP surface smoother and reducing surface corrosion and oxidation, thereby improving the surface quality after polishing. In contrast, surfactants with shorter hydrophobic chains, such as DTAC and CTAC, have weaker surface adsorption and interfacial activity, and may not effectively inhibit excessive oxidation or surface corrosion, resulting in a surface quality inferior to that after STAC treatment. Due to its strong hydrophobicity and molecular structure, STAC can improve the dispersibility of silica particles in the polishing solution, reducing particle aggregation and precipitation. This allows the particles to act uniformly on the InP surface during polishing, thereby increasing the removal rate. In contrast, short-chain surfactants such as DTAC, CTAC, and TDBAC may cause particle deposition or agglomeration, reducing the removal rate.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be included in the protection scope of the present invention.

[0065] Matters not covered in this invention are common knowledge.

Claims

1. A sodium dichloroisocyanurate complex polishing solution for improving the removal rate and surface quality of indium phosphide, characterized by, The component ingredients of the polishing liquid include: nano-silicon dioxide concentration of 8.0-12.0 wt.%, oxidant concentration of 0.8-1.1 wt.%, complexing agent concentration of 0.8-1.1 wt.%, surfactant concentration of 200-500 ppm, and the balance is deionized water; the pH value of the polishing liquid system is 8.9-9.1; The oxidant is sodium dichloroisocyanurate, the complexing agent is potassium sorbate, and the cationic surfactant is octadecyl trimethyl ammonium chloride.

2. The sodium dichloroisocyanurate complex polishing solution for improving the removal rate and surface quality of indium phosphide according to claim 1, characterized by, The particle size of the nano-silicon dioxide is 30-50 nm.

3. The sodium dichloroisocyanurate complex polishing solution for improving the removal rate and surface quality of indium phosphide according to claim 1, characterized by, The pH regulator is one or both of nitric acid and potassium hydroxide.

4. The method for preparing a high-efficiency polishing slurry of sodium dichloroisocyanurate composite abrasive to improve the removal rate and surface quality of indium phosphide as described in claim 1, characterized in that: The method comprises the following steps: Step S1: add 35-45 wt.% nano-SiO2 sol in a beaker, and slowly add deionized water to the beaker to dilute the nano-silicon dioxide in the SiO2 sol to a concentration of 8.0-12.0 wt.%; Step S2: then add the oxidant sodium dichloroisocyanurate, the complexing agent potassium sorbate, and the surfactant octadecyl trimethyl ammonium chloride to the solution obtained in step S1 in sequence; Step S3: add the balance of deionized water to the solution obtained in step S2 until the target volume, and then place the beaker on a stirrer and stir for 4-6 minutes; Step S4: adjust the pH of the solution obtained in step S3 to the target pH by using nitric acid (HNO3) and potassium hydroxide (KOH).

5. The use of a composite abrasive polishing liquid for improving the removal rate and surface quality of InP according to claim 1, characterized in that Chemical mechanical polishing is performed on an indium phosphide substrate.

6. The use of a composite abrasive polishing liquid for improving the removal rate and surface quality of indium phosphide according to claim 5, characterized in that The polishing machine for the polishing is Rui Xuan SSP-500, and the polishing conditions are: The polishing time is 310 s (liquid polishing for 300 s and water polishing for 10 s), the polishing pressure is 3.29 psi (14 kg), the polishing liquid flow rate is 80 ml / min, the polishing head rotation speed is 50 rad / min, and the polishing disc rotation speed is 50 rad / min.

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