A Chemical Mechanical Polishing Liquid and Its Application

Abstract

The present invention provides a chemical mechanical polishing liquid and its application, which includes abrasive particles, polishing accelerators, oxidants, surfactants, pH regulators and water; the polishing accelerators include inorganic salts of alkali metals and organic salts of alkali metals; the inorganic salts of alkali metals include one or more of carbonates of alkali metals, bicarbonates of alkali metals, nitrates of alkali metals and sulfates of alkali metals; the organic salts of alkali metals include one or more of oxalates of alkali metals, acetates of alkali metals, citrates of alkali metals, phthalates of alkali metals and diaminetetraacetates of alkali metals. The present invention realizes one-step forming of GaSb single crystal wafer polishing, has a simple process and good stability, shortens the original polishing time from more than 2 hours to about 15 minutes, and the surface of the GaSb single crystal wafer is smooth, without defects such as scratches, orange peel, and matte surface, and the roughness Ra can reach below 0.3 nm.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductors, and particularly relates to a chemical mechanical polishing liquid and its application. Background Art

[0002] III-V compound semiconductors are compound semiconductor materials formed by the combination of group III elements and group V elements. The commonly used group III elements are mainly boron, aluminum, gallium, and indium, and the commonly used group V elements are mainly nitrogen, phosphorus, arsenic, and antimony. Gallium antimonide (GaSb), similar to indium phosphide (InP) and gallium arsenide (GaAs), is a typical III-V compound semiconductor material with the same zinc blende structure in the cubic crystal system. Compared with GaAs and InP, the surface chemistry of GaSb wafers is active and easily oxidized. An oxide layer of several nanometers can rapidly form on the surface in air. The passivation effect of antimony oxides and their limited solubility make the chemical treatment of GaSb quite difficult.

[0003] In recent years, infrared detectors developed from epitaxial antimonide type-II superlattice materials with GaSb as the substrate material have shown excellent detection performance in the long-wave and very long-wave infrared bands, and have good application prospects in fields such as gas monitoring, night vision, and infrared imaging. The epitaxial growth of high-quality antimonide type-II superlattice materials places high quality requirements on GaSb substrate materials, which need to have a low defect density, high lattice integrity, and an epitaxial buffer layer with atomic-level flatness. This poses very high requirements for the surface quality of GaSb substrates, and their application depends on the development of polishing technology. GaSb wafers are soft and brittle, and prone to scratching. Therefore, it is necessary to conduct in-depth research to solve the processing technology problems.

[0004] In order to obtain a high-quality GaSb material surface, CN116652700A provides a manual polishing method for GaSb single-crystalline wafers, and the surface roughness Ra of the wafers can reach below 0.70 nm. However, manual polishing is difficult to standardize and highly dependent on human factors; CN106064326B discloses a polishing method for GaSb single-crystalline wafers. After polishing, the surface damage of GaSb single-crystalline wafers is small, easy to clean, and the surface roughness is less than 0.30 nm. However, the entire polishing process is divided into rough polishing, medium polishing, and fine polishing, and the polishing cloth, polishing liquid, and polishing parameters used are all different. The process is complex and the use cost is relatively high. Summary of the Invention

[0005] The purpose of the present invention is to provide a chemical mechanical polishing liquid and its application. The chemical mechanical polishing liquid in the present invention can enable GaSb single-crystalline wafers to obtain a high-quality surface with low roughness only through one-step polishing.

[0006] The present invention provides a chemical mechanical polishing liquid, which comprises abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH regulator and water;

[0007] The polishing accelerator comprises inorganic salts of alkali metals and organic salts of alkali metals;

[0008] The inorganic salts of alkali metals include one or more of carbonates of alkali metals, bicarbonates of alkali metals, nitrates of alkali metals and sulfates of alkali metals;

[0009] The organic salts of alkali metals include one or more of oxalates of alkali metals, acetates of alkali metals, citrates of alkali metals, phthalates of alkali metals and diaminetetraacetates of alkali metals;

[0010] In the chemical mechanical polishing liquid, the mass ratio of the inorganic salts of alkali metals to the organic salts of alkali metals is (0.2 wt% - 2 wt%):(0.05 wt% - 0.5 wt%).

[0011] Preferably, the abrasive particles include one or more of alumina, cerium dioxide, silica, titanium dioxide and zirconium oxide;

[0012] And / or, the average particle size of the abrasive particles is 10 - 1000 nm;

[0013] And / or, the inorganic salts of alkali metals include one or more of nitrates of alkali metals;

[0014] And / or, the organic salts of alkali metals include one or more of C2 - C6 alkylene or cycloalkylene diaminetetraacetates;

[0015] And / or, the oxidant includes one or more of bromates, bromites, chlorates, chlorites, hydrogen peroxide, hypochlorites, iodates, monopersulfates, monopersulfites, monoperphosphates, monoperpyrophosphates, organic - halogen - oxides, periodates, permanganates, peracetic acid and iron salts;

[0016] And / or, the surfactant includes one or more of anionic surfactants and non - ionic surfactants;

[0017] And / or, the pH regulator includes one or two of an acid regulator and a base regulator;

[0018] And / or, the pH value of the chemical mechanical polishing liquid is 9.2 - 10.2.

[0019] Preferably, the abrasive particles include one or more of colloidal silica, fumed silica, precipitated silica and condensed silica;

[0020] and / or, the average particle size of the abrasive particles is 50 - 500 nm;

[0021] and / or, the inorganic acid salts of the alkali metal include one or both of potassium nitrate and sodium nitrate;

[0022] and / or, the organic acid salts of the alkali metal include one or more of trans - 1,2 - cyclohexanediaminetetraacetate and ethylenediaminetetraacetate;

[0023] and / or, the oxidizing agent is a peroxide, and the peroxide includes one or more of hydrogen peroxide, monopersulfate, monopersulfite, monoperphosphate, monoperoxydiphosphate, monoperoxypyrophosphate, and peracetic acid;

[0024] and / or, the surfactant includes one or more of ethoxylated propoxylated fatty alcohols, alkoxylated branched fatty alcohols, linear secondary alcohol polyoxyethylene ethers, polyethylene glycol stearates, sodium lauryl ether sulfate, sarcosinates and taurates, dodecylbenzenesulfonic acid, alkyl carboxylic acid isomeric polyolamines, and acetylenic glycol ethoxylates;

[0025] and / or, the pH regulator is an acid regulator, and the acid regulator includes one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, and oxalic acid;

[0026] and / or, the pH regulator is a base regulator, and the base regulator includes one or more of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ethylenediamine, and phenethylamine.

[0027] Preferably, the polishing liquid further includes an additive, and the additive includes one or more of a buffer, a biocide, a scale inhibitor, an antifoaming agent, and a dispersant.

[0028] Preferably, by mass percentage, the mass percentage content of the abrasive particles in the polishing liquid is 0.1 wt% - 30 wt%;

[0029] and / or, the mass percentage content of the inorganic acid salts of the alkali metal in the polishing liquid is 0.2 wt% - 2 wt%;

[0030] and / or, the mass percentage content of the organic acid salts of the alkali metal in the polishing liquid is 0.05 wt% - 0.5 wt%;

[0031] and / or, the mass percentage content of the oxidizing agent in the polishing liquid is 0.01 wt% - 8 wt%;

[0032] and / or, the mass percentage content of the surfactant in the polishing liquid is 0.001 wt% - 1 wt%.

[0033] Preferably, by mass percentage, the mass percentage content of the abrasive particles in the polishing liquid is 0.2 wt% to 25 wt%;

[0034] and / or, the mass percentage content of the inorganic acid salt of the alkali metal in the polishing liquid is 0.2 wt% to 1.5 wt%;

[0035] and / or, the mass percentage content of the organic acid salt of the alkali metal in the polishing liquid is 0.05 wt% to 0.4 wt%;

[0036] and / or, the mass percentage content of the oxidant in the polishing liquid is 0.02 wt% to 5 wt%;

[0037] and / or, the mass percentage content of the surfactant in the polishing liquid is 0.01 wt% to 0.5 wt%.

[0038] Preferably, the polishing liquid includes silica abrasive particles, potassium nitrate, trans-1,2-cyclohexanediaminetetraacetate, hydrogen peroxide, surfactant, pH regulator and water; the surfactant is linear secondary alcohol polyoxyethylene ether and / or polyethylene glycol stearate.

[0039] The present invention provides the application of the chemical mechanical polishing liquid as described above in the polishing of GaSb single crystal wafers.

[0040] Preferably, the polishing of the GaSb single crystal wafer includes the following steps:

[0041] A) Chemically mechanically polish the GaSb single crystal wafer using a polishing cloth in combination with the chemical mechanical polishing liquid;

[0042] B) Clean the polished GaSb single crystal wafer.

[0043] Preferably, in step A), the GaSb single crystal is polished by a polishing machine, the polishing rotation speed is 20 rpm to 70 rpm, and the polishing pressure is 300 g / cm 2 ~800 g / cm 2 , the dropping rate of the chemical mechanical polishing liquid is 10 mL / min to 50 mL / min, and the polishing time is 5 min to 15 min;

[0044] and / or, in step A), the polishing cloth is made of polyurethane;

[0045] and / or, in step B), after the GaSb single crystal wafer is rinsed with deionized water, it is scrubbed with ethanol, then sprayed with deionized water, and finally dried with nitrogen.

[0046] The present invention provides a chemical mechanical polishing liquid, which comprises abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH regulator and water; the polishing accelerator comprises inorganic acid salts of alkali metals and organic acid salts of alkali metals; the inorganic acid salts of alkali metals include one or more of carbonates of alkali metals, bicarbonates of alkali metals, nitrates of alkali metals and sulfates of alkali metals; the organic acid salts of alkali metals include one or more of oxalates of alkali metals, acetates of alkali metals, citrates of alkali metals, phthalates of alkali metals and alkylenediaminetetraacetates of alkali metals; in the chemical mechanical polishing liquid, the mass ratio of the inorganic acid salts of alkali metals to the organic acid salts of alkali metals is (0.2 wt% - 2 wt%):(0.05 wt% - 0.5 wt%). By optimizing the components and contents of the polishing liquid, the present invention realizes one-step forming of GaSb single crystal wafer polishing, without going through three-step polishing of rough polishing, medium polishing and fine polishing. The process is simple and has good stability, shortening the original polishing time from more than 2 hours to about 15 minutes. The GaSb single crystal wafer obtained by the polishing method described in the above technical solution has a high-quality surface, and the surface is smooth, without defects such as scratches, orange peel, and matte surface, and the roughness Ra can reach below 0.3 nm. Detailed Embodiments

[0047] The present invention provides a chemical mechanical polishing liquid, which comprises abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH regulator and water;

[0048] The polishing accelerator comprises inorganic acid salts of alkali metals and organic acid salts of alkali metals;

[0049] The inorganic acid salts of alkali metals include one or more of carbonates of alkali metals, bicarbonates of alkali metals, nitrates of alkali metals and sulfates of alkali metals;

[0050] The organic acid salts of alkali metals include one or more of oxalates of alkali metals, acetates of alkali metals, citrates of alkali metals, phthalates of alkali metals and alkylenediaminetetraacetates of alkali metals;

[0051] In the chemical mechanical polishing liquid, the mass ratio of the inorganic acid salts of alkali metals to the organic acid salts of alkali metals is (0.2 wt% - 2 wt%):(0.05 wt% - 0.5 wt%).

[0052] In the present invention, the chemical mechanical polishing liquid can achieve excellent polishing effects for GaSb wafers with high polishing difficulty and shorten the total polishing time, and is also applicable to the chemical mechanical polishing treatment of compound semiconductor materials formed by the combination of group III elements and group V elements, such as GaAs, InP, GaSb, InAs, InSb, InAsSb, InGaAs, AlGaSb, InAlSb, AlGaAsSb, GaInAsSb, etc. On the contrary, considering the higher polishing difficulty demonstrated by GaSb wafers during polishing, polishing liquids applicable to other semiconductor materials are difficult to achieve the technical effects of the polishing liquid in the present invention.

[0053] In the present invention, the abrasive grains preferably include one or more of alumina, cerium dioxide, silicon dioxide, titanium dioxide, and zirconium dioxide, more preferably silicon dioxide. The silicon dioxide can be in any suitable form of silicon dioxide, such as including one or more of colloidal silicon dioxide, pyrogenic silicon dioxide, precipitated silicon dioxide, and condensed silicon dioxide. The average particle size of the abrasive grains is preferably 10 - 1000 nm, more preferably 50 - 500 nm, and further preferably 70 - 300 nm. Specifically, for example, 10 nm, 30 nm, 50 nm, 70 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, and preferably a range value with any of the above-mentioned values as the upper or lower limit.

[0054] In the present invention, the abrasive grains are suspended in the polishing liquid. The mass percentage content of the abrasive grains in the chemical mechanical polishing liquid is preferably 0.1% - 30%, more preferably 0.2% - 25%, such as 0.1%, 0.2%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, and preferably a range value with any of the above-mentioned values as the upper or lower limit.

[0055] In the present invention, the polishing accelerator can chemically react with the material to be polished or combine with one of the components in the material to be polished to form a substance or bond with a relatively weak binding force, so as to increase the removal rate of the material to be polished. The polishing accelerator preferably includes inorganic salts of alkali metals and organic salts of alkali metals.

[0056] In the present invention, the inorganic acid salts of alkali metals include one or more of carbonates of alkali metals, bicarbonates of alkali metals, nitrates of alkali metals, and sulfates of alkali metals; the alkali metals in the inorganic acid salts of alkali metals are preferably one or more of lithium, sodium, and potassium; specifically, in the embodiments of the present invention, the inorganic acid salts of alkali metals may be one or more of potassium nitrate, potassium sulfate, and potassium carbonate, and the mass percentage content of the inorganic acid salts of alkali metals in the chemical mechanical polishing liquid is preferably 0.2% to 2%, more preferably 0.2% to 1.5%, still more preferably 0.5% to 1.5%, such as 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, and is preferably a range value with any of the above values as the upper or lower limit.

[0057] In the present invention, the organic acid salts of alkali metals include one or more of oxalates of alkali metals, acetates of alkali metals, citrates of alkali metals, phthalates of alkali metals, and diaminetetraacetates of alkali metals, more preferably include one or more of C2-C6 alkylene or cycloalkylene diaminetetraacetates, such as ethylenediaminetetraacetate and / or 1,2-cyclohexanediaminetetraacetate; the alkali metals in the organic acid salts of alkali metals are preferably one or more of lithium, sodium, and potassium; specifically, in the embodiments of the present invention, the organic acid salts of alkali metals may be one or more of sodium citrate, disodium ethylenediaminetetraacetate, and 1,2-cyclohexanediaminetetraacetate; the mass percentage content of the organic acid salts of alkali metals in the chemical mechanical polishing liquid is preferably 0.05% to 0.5%, more preferably 0.05% to 0.4%, still more preferably 0.1% to 0.4%, such as 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, and is preferably a range value with any of the above values as the upper or lower limit.

[0058] In the present invention, the oxidizing agent preferably includes one or more of bromates, bromites, chlorates, chlorites, hydrogen peroxide, hypochlorites, iodates, monopersulfates, monopersulfites, monoperphosphates, monoperpyrophosphates, organic-halogen-oxidation compounds, periodates, permanganates, peracetic acid, and iron salts (such as iron nitrate); the mass percentage content of the oxidizing agent in the chemical mechanical polishing liquid is preferably 0.01 to 8%, more preferably 0.02% to 5%, such as 0.01%, 0.02%, 0.05%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, and is preferably a range value with any of the above values as the upper or lower limit.

[0059] In the present invention, the surfactant is preferably an anionic surfactant and / or a non-ionic surfactant, such as one or more of ethoxylated propoxylated fatty alcohols, alkoxylated branched fatty alcohols, linear secondary alcohol polyoxyethylene ethers, polyethylene glycol stearates, sodium lauryl ether sulfate, sarcosinates and taurates, dodecylbenzenesulfonic acid, alkyl carboxylic acid isomeric polyol amines and alkynediol ethoxylates; the mass percentage content of the surfactant in the chemical mechanical polishing liquid is preferably 0.001% - 1%, more preferably 0.01% - 0.5%, such as 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, preferably a range value with any of the above values as the upper or lower limit.

[0060] In the present invention, the pH regulator preferably includes an acid regulator and / or a base regulator. The acid regulator is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid and oxalic acid, and the base regulator is one or more of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ethylenediamine and phenethylamine; the pH value of the chemical mechanical polishing liquid is preferably 9.2 - 10.2.

[0061] According to actual needs, the chemical mechanical polishing liquid in the present invention may further include other additives, such as one or more of a buffer, a biocide, a scale inhibitor, an antifoaming agent and a dispersant.

[0062] The present invention does not impose special restrictions on the preparation method of the chemical mechanical polishing liquid. It can be obtained by mixing the above-mentioned abrasive particles, polishing accelerators, oxidants, surfactants, pH regulators and water in a conventional mixing manner. Among them, the oxidant may decompose in the presence of some additives. In this case, the oxidant can be added before use.

[0063] The present invention also provides an application of the above-mentioned chemical mechanical polishing liquid in polishing a GaSb single crystal wafer. The polishing of the GaSb single crystal wafer includes the following steps:

[0064] A) Chemically mechanically polish the GaSb single crystal wafer with the above-mentioned chemical mechanical polishing liquid;

[0065] B) Clean the polished GaSb single crystal wafer.

[0066] The present invention preferably uses a polishing cloth in combination with the chemical mechanical polishing liquid described above to perform chemical mechanical polishing on a GaSb single crystal wafer. Before chemical mechanical polishing, the GaSb single crystal wafer to be polished is placed and fixed in a wax-free adsorption pad soaked in water.

[0067] In the present invention, the polishing cloth is preferably a polishing cloth made of polyurethane material, more preferably a black polyurethane material polishing cloth. The rotation speed of the chemical mechanical polishing is preferably 20 - 70 rpm, more preferably 30 - 60 rpm, such as 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, and is preferably a range value with any of the above values as the upper or lower limit; the pressure of the chemical mechanical polishing is preferably 300 - 800 g / cm 2 ², more preferably 400 - 700 g / cm 2 ², such as 300 g / cm 2 ², 400 g / cm 2 ², 500 g / cm 2 ², 600 g / cm 2 ², 700 g / cm 2 ², 800 g / cm 2 ², and is preferably a range value with any of the above values as the upper or lower limit; during the chemical mechanical polishing process, the dropping speed of the chemical mechanical polishing liquid is preferably 10 - 50 mL / min, more preferably 20 - 40 mL / min, such as 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min, 30 mL / min, 35 mL / min, 40 mL / min, 45 mL / min, 50 mL / min, and is preferably a range value with any of the above values as the upper or lower limit; the time of the chemical mechanical polishing varies according to the removal amount. Generally, when the removal amount is 5 - 20 μm, the chemical mechanical polishing time is 5 min - 15 min, more preferably 8 min - 12 min, such as 5 min, 6 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, and is preferably a range value with any of the above values as the upper or lower limit.

[0068] After completing the chemical mechanical polishing, the present invention rinses the polished GaSb single crystal wafer with deionized water and then wipes it with ethanol, and then sprays it with deionized water and dries it with nitrogen to obtain the polished GaSb single crystal wafer.

[0069] The present invention provides a chemical mechanical polishing liquid, comprising abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH regulator and water; the polishing accelerator comprises inorganic acid salts of alkali metals and organic acid salts of alkali metals; the inorganic acid salts of alkali metals include one or more of carbonates of alkali metals, bicarbonates of alkali metals, nitrates of alkali metals and sulfates of alkali metals; the organic acid salts of alkali metals include one or more of oxalates of alkali metals, acetates of alkali metals, citrates of alkali metals, phthalates of alkali metals and alkylenediaminetetraacetates of alkali metals; in the chemical mechanical polishing liquid, the mass ratio of the inorganic acid salt of alkali metal to the organic acid salt of alkali metal is (0.2 wt% - 2 wt%):(0.05 wt% - 0.5 wt%). By optimizing the selection of the components and contents of the polishing liquid, the present invention realizes one-step forming of GaSb single crystal wafer polishing, without going through three-step polishing of rough polishing, medium polishing and fine polishing. The process is simple and has good stability, shortening the original polishing time from more than 2 hours to about 15 minutes. The GaSb single crystal wafer obtained by the polishing method described in the above technical solution has a high-quality surface, and the surface is smooth, without defects such as scratches, orange peel, and matte surface, and the roughness Ra can reach below 0.3 nm.

[0070] In order to further illustrate the present invention, the following is a detailed description of a chemical mechanical polishing liquid and its application provided by the present invention in combination with embodiments, but it should not be construed as a limitation to the protection scope of the present invention.

[0071] Example 1 Influence of pH on GaSb single crystal wafer polishing

[0072] Use polishing liquids with different pH values to chemically mechanically polish GaSb single crystal wafers (see Experimental Examples 1A, 1B, 1C in Table 1). Except for using potassium hydroxide solution to adjust the pH to 9.1, 10.2, and 11.2 respectively, the polishing liquids used in all experimental examples contain 20% colloidal silica, 1% potassium nitrate, 0.2% potassium trans-1,2-cyclohexanediaminetetraacetate, and 3% hydrogen peroxide, and the rest is deionized water. The polishing uses a black non-grooved polyurethane polishing pad, the polishing speed is 50 rpm, the downward pressure is 25 N, and the flow rate of the polishing liquid is 20 ml / min. Place the GaSb single crystal wafer in a wax-free adsorption pad soaked in deionized water, place it on a single-sided polishing machine for polishing, and the polishing time is 5 min. Immediately after the polishing is completed, remove the GaSb single crystal wafer, rinse it with overflowing deionized water, then wipe it with ethanol and dry it with nitrogen. Use an electronic analytical balance with a precision of 0.0001 g to weigh and compare the mass change before and after polishing, calculate the removal rate of the GaSb single crystal wafer through the mass change, and obtain the roughness of the GaSb single crystal wafer through an atomic force microscope (the scanning range is 5x5 μm). The experimental results are shown in Table 1:

[0073] Table 1: GaSb Removal Rate and Roughness

[0074]

[0075] It can be seen from the data in Table 1 that as the pH increases, the roughness shows a gradually increasing trend. When the pH is 9.2, a relatively high removal rate and a relatively low roughness can be achieved. When the pH rises to 10.2, the removal rate decreases by about 15%. When the pH continues to rise to 11.2, the removal rate further decreases. This shows that for the chemical mechanical polishing of GaSb, the higher the pH, the lower the removal rate. To further verify this conjecture, the pH was decreased to 8.2, and it was found that the polishing liquid particles aggregated, resulting in poor stability of the entire system. Therefore, the optimal polishing pH range for this system is 9.2 - 10.2.

[0076] Example 2: Influence of Oxidant Concentration on the Polishing of GaSb Single Crystal Wafers

[0077] Use polishing liquids with different oxidant concentrations to chemically mechanically polish GaSb single crystal wafers (Experimental Examples 2A, 2B, 2C, 2D). Except for containing different concentrations of hydrogen peroxide, the polishing liquids used in all experimental examples contain 20% colloidal silica, 1% potassium nitrate, 0.2% potassium trans - 1,2 - cyclohexanediaminetetraacetate, and the pH is adjusted to 10.2 with potassium hydroxide, and the rest is deionized water. The polishing parameters and the cleaning method of the GaSb single crystal wafers are the same as those in Example 1. Use an electronic analytical balance with a precision of 0.0001 g to weigh the mass change before and after polishing, and calculate the removal rate of the GaSb single crystal wafer through the mass change. The experimental results are shown in Table 2:

[0078] Table 2 GaSb Removal Rate

[0079]

[0080] It can be known from the data in Table 2 that when the hydrogen peroxide concentration increases from 2% to 3%, the removal rate slightly increases. When the hydrogen peroxide concentration rises to 5%, the removal rate decreases by 50%. When the hydrogen peroxide concentration continues to rise to 7%, the removal rate slightly increases but cannot reach the level when the hydrogen peroxide concentration is 3%. In addition, as the hydrogen peroxide concentration increases, the roughness experiences a trend of first decreasing and then increasing, and reaches the lowest at a concentration of 3%, indicating that when the hydrogen peroxide concentration is 3%, a relatively high GaSb removal rate and a relatively low roughness can be achieved.

[0081] Example 3: Influence of Polishing Promoter on the Polishing of GaSb Single Crystal Wafers

[0082] A chemical mechanical polishing of GaSb single crystal wafers was carried out using polishing liquids containing different types of accelerators (Experimental Examples 3A, 3B, 3C, 3D, 3E, 3F). The polishing liquids used in Experimental Examples 3A - 3E all contained 20% colloidal silica, 1% potassium nitrate, 3% hydrogen peroxide, and the pH was adjusted to 9.2 with potassium hydroxide. Except for 3E which did not contain organic salts, Experimental Examples 3A - 3D and 3G all contained 0.2% of different types of organic salts, and the rest was deionized water. In addition, Experimental Examples 3E - 3G were used to illustrate the synergistic accelerating effect of potassium nitrate and organic salts. The polishing parameters and the cleaning method of the GaSb single crystal wafers were the same as those in Example 1. An electronic analytical balance with a precision of 0.0001 g was used to weigh the mass change before and after polishing for comparison, and the removal rate of the GaSb single crystal wafer was calculated based on the mass change. The roughness of the GaSb single crystal wafer was obtained by an atomic force microscope (the scanning range was 5x5 μm). The experimental results are shown in Table 3:

[0083] Table 3 GaSb Removal Rate and Roughness

[0084]

[0085] Analyzing Table 3, it can be seen from 3A - 3D that different types of organic salts and potassium nitrate can affect the GaSb removal rate and surface roughness to varying degrees. Compared with Experimental Example 3F, Experimental Example 3E added 1% potassium nitrate alone, and while the roughness decreased, the removal rate also increased (Rate 0.89 μm / min, a 71.15% increase compared to 3E). However, the improvement of potassium nitrate on the surface roughness and GaSb removal rate is limited. Preferably, the addition amount of potassium nitrate does not exceed 2%. Further increasing the potassium nitrate content will affect the stability of the polishing liquid. Compared with Experimental Example 3F, Experimental Example 3G added 0.2% potassium trans - 1,2 - cyclohexanediaminetetraacetate alone, and the GaSb removal rate increased significantly (Rate 1.27 μm / min, a 144.23% increase compared to 3E). Compared with Experimental Example 3F, Experimental Example 3D added 1% potassium nitrate and 0.2% potassium trans - 1,2 - cyclohexanediaminetetraacetate simultaneously, and the GaSb removal rate increased significantly (Rate 4.95 μm / min, an 851.92% increase compared to 3E). The effect is far beyond that of adding 1% potassium nitrate or 0.2% potassium trans - 1,2 - cyclohexanediaminetetraacetate alone, indicating that the two have a synergistic effect on the improvement of the GaSb removal rate.

[0086] In summary, both inorganic salts and organic salts can accelerate the removal rate of GaSb to varying degrees. When both are present in the polishing liquid, the removal rate of GaSb increases significantly, indicating a synergistic effect between them.

[0087] Example 4 Effect of Surfactants on the Polishing of GaSb Single Crystal Wafers.

[0088] GaSb single crystal wafers were polished using surfactants with the same concentration but different types (Experimental Examples 4A - 4I). The polishing solutions used in all experimental examples contained 20% colloidal silica, 1% potassium nitrate, 0.2% potassium trans - 1,2 - cyclohexanediaminetetraacetate, and 3% hydrogen peroxide, with the rest being deionized water. Experimental Example 4J was used as a control and did not contain any surfactant. Except for Experimental Example 4J containing 0.2% of different types of surfactants, the polishing parameters and the cleaning method of the GaSb single crystal wafers were the same as those in Example 1. An electronic analytical balance with a precision of 0.0001 g was used to weigh the mass change before and after polishing, and the removal rate of the GaSb single crystal wafer was calculated based on the mass change. The roughness of the GaSb single crystal wafer was obtained using an atomic force microscope (scanning range: 5x5 μm). The experimental results are shown in Table 4:

[0089] Table 4 GaSb Removal Rate and Roughness

[0090]

[0091] From the data in Table 4, it can be seen that different types of surfactants have varying degrees of influence on the removal rate and roughness of GaSb single crystal wafers. The roughness of Experimental Examples 4C / 4D is better (Ra ≤ 0.5 nm). At the same time, the removal rate decreases but still meets the requirements of the one - step GaSb polishing process. One - step forming of GaSb single crystal wafer polishing is achieved, eliminating the need for three - step polishing of rough polishing, intermediate polishing, and fine polishing. The process is simple and has good stability, shortening the original polishing time from more than 2 hours to about 15 minutes. When observing the surface of the wafers polished in Experimental Examples 4C / 4D under strong light, the surface is flat, smooth, and free of matte, scratches, and particle residues.

[0092] Example 5 Synergistic Effect between Polishing Promoters

[0093] Example 3 verified that in the case of not adding surfactants, the two polishing promoters, inorganic acid salts and organic acid salts, have a synergistic effect on enhancing the removal rate of GaSb. This example explores the influence of the two on the GaSb polishing rate when surfactants are added.

[0094] Polishing accelerators of different concentrations and types were used to polish GaSb single wafers (Experimental Examples 5A-5F). The polishing liquid used in all experimental examples contained 20% colloidal silica, 0.2% linear secondary alcohol polyoxyethylene ether, and 3% hydrogen peroxide. Experimental Example 5G, as a comparative example, did not contain alkali metal inorganic salts. The remaining experimental examples contained alkali metal inorganic salts and / or trans-1,2-cyclohexanediaminetetraacetic acid potassium of different concentrations and types. The polishing parameters and the cleaning method of the GaSb single wafer were the same as those in Example 1. An electronic analytical balance with an accuracy of 0.0001 g was used to weigh and compare the mass change before and after polishing. The removal rate of the GaSb single wafer was calculated by the mass change. The roughness of the GaSb single wafer was obtained by atomic force microscopy (scanning range was 5x5μm). The experimental results are shown in Table 4:

[0095] Table 5 GaSb removal rate and roughness

[0096]

[0097] Analyzing the data in Table 5, the polishing accelerator of Experimental Example 5F is 1.2% potassium nitrate, the removal rate of GaSb is 0.44μm / min, and the roughness is >2nm. The polishing accelerator of Experimental Example 5G is 0.5% trans-1,2-cyclohexanediaminetetraacetic acid potassium, the removal rate of GaSb is 0.32μm / min, and the roughness is >2nm. Further increase in the content of organic acid salts does not further increase the removal rate of GaSb, but affects the stability of the polishing liquid. Therefore, the addition amount of organic acid salts is preferably not more than 0.5%. The polishing accelerator of Experimental Example 5B is 1% potassium nitrate and 0.2% trans-1,2-cyclohexanediaminetetraacetic acid potassium, the removal rate of GaSb is 0.78μm / min, and the roughness is 0.2nm. While the roughness is significantly reduced, the removal rate of GaSb is significantly improved, which is significantly better than 5F and 5G, indicating that there is a synergistic effect between organic acid salts and inorganic acid salts.

[0098] The different removal rates and roughness of Experimental Examples 5B, 5D, and 5E indicate that the synergistic effects of different types of inorganic acid salts and the same organic acid salts are not the same. While the removal rate of Experimental Example 5B is higher, a lower roughness can be achieved. The surface of the wafer after polishing in Experimental Example 5B is observed under strong light. The surface is smooth and has no matte surface, scratches, or residual particles. The polished GaSb in Experimental Examples 5D and 5E is difficult to clean, and there are more particles remaining on the surface, so the roughness is higher.

[0099] The results of Experimental Examples 5A - 5C illustrate that different potassium nitrate concentrations have significant effects on both the removal rate and roughness of GaSb. As the potassium nitrate concentration increases, the removal rate of GaSb gradually rises. However, compared with Experimental Example 5B, the roughness of GaSb after polishing in Experimental Example 5C is higher, and the state of the polishing liquid is not good, with easy delamination. Therefore, the content of potassium nitrate should not be greater than 2 wt%.

[0100] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A chemical mechanical polishing liquid comprising abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH regulator and water; The polishing accelerator includes an inorganic acid salt of an alkali metal and an organic acid salt of an alkali metal; The inorganic acid salt of the alkali metal includes one or more nitrates of the alkali metal; The organic acid salt of the alkali metal includes one or more of trans-1,2-cyclohexanediaminetetraacetate and ethylenediaminetetraacetate; In the chemical mechanical polishing liquid, the mass ratio of the inorganic acid salt of the alkali metal to the organic acid salt of the alkali metal is (0.2 wt%~2wt%): (0.05 wt%~0.5wt%); The pH value of the chemical mechanical polishing liquid is 9.2-10.2; In terms of mass percentage, the mass percentage of the abrasive particles in the polishing liquid is 0.1 wt% to 30wt%; The mass percentage of the inorganic acid salt of the alkali metal in the polishing liquid is 0.2 wt% to 2wt%; The mass percentage of the organic acid salt of the alkali metal in the polishing liquid is 0.05 wt% to 0.5 wt%; The mass percentage of the oxidant in the polishing liquid is 0.01 wt%~8wt%; The mass percentage of the surfactant in the polishing liquid is 0.001 wt%~1wt%.

2. The chemical mechanical polishing solution according to claim 1, characterized in that: The abrasive particles include one or more of aluminum oxide, ceria, silicon dioxide, titanium dioxide and zirconium oxide; And / or, the average particle size of the abrasive particles is 10 to 1000 nm; and / or, the oxidant comprises one or more of bromate, bromite, chlorate, chlorite, hydrogen peroxide, hypochlorite, iodate, monoperoxysulfate, monoperoxysulfite, monoperoxyphosphate, monoperoxyhypodyphosphate, monoperoxypyrophosphate, organic-halogen-oxygen compound, periodate, permanganate, peracetic acid and iron salt; And / or, the surfactant includes one or more of anionic surfactants and nonionic surfactants; And / or, the pH regulator includes one or both of an acid regulator and an alkali regulator.

3. The chemical mechanical polishing solution according to claim 1, characterized in that: The abrasive particles include one or more of colloidal silica, pyrogenic silica, precipitated silica and condensation-polymerized silica; And / or, the average particle size of the abrasive particles is 50-500 nm; And / or, the inorganic acid salt of the alkali metal includes one or both of potassium nitrate and sodium nitrate; And / or, the oxidant is a peroxide, and the peroxide includes one or more of hydrogen peroxide, monopersulfate, monopersulfite, monoperphosphate, monoperoxydiphosphate, monoperoxypyrophosphate, and peracetic acid; and / or, the surfactant comprises one or more of ethoxypropoxylated fatty alcohols, alkoxylated branched fatty alcohols, linear secondary alcohol polyoxyethylene ethers, polyethylene glycol stearates, fatty alcohol polyoxyethylene ether sodium sulfates, sarcosinates and taurates, dodecylbenzenesulfonic acid, alkyl carboxylic acid isomeric polyol amines, and acetylene glycol ethoxylates; And / or, the pH regulator is an acid regulator, and the acid regulator includes one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid and oxalic acid; And / or, the pH regulator is an alkali regulator, and the alkali regulator includes one or more of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ethylenediamine and phenylethylamine.

4. The chemical mechanical polishing solution according to claim 1, characterized in that: The polishing liquid further includes additives, which include one or more of a buffer, a biocide, an antiscalant, a defoamer, and a dispersant.

5. The chemical mechanical polishing solution according to claim 1, characterized in that: In terms of mass percentage, the mass percentage of the abrasive particles in the polishing liquid is 0.2 wt% to 25 wt%; And / or, the mass percentage of the inorganic acid salt of the alkali metal in the polishing liquid is 0.2 wt%~1.5wt%; And / or, the mass percentage of the organic acid salt of the alkali metal in the polishing liquid is 0.05 wt% to 0.4 wt%; And / or, the mass percentage of the oxidant in the polishing liquid is 0.02 wt%~5wt%; And / or, the mass percentage of the surfactant in the polishing liquid is 0.01 wt%~0.5wt%.

6. The chemical mechanical polishing solution according to claim 1, characterized in that: The polishing liquid comprises silicon dioxide abrasive particles, potassium nitrate, trans-1,2-cyclohexanediaminetetraacetate, hydrogen peroxide, a surfactant, a pH regulator and water; the surfactant is a linear secondary alcohol polyoxyethylene ether and / or polyethylene glycol stearate.

7. Use of the chemical mechanical polishing liquid as claimed in any one of claims 1 to 6 in polishing a GaSb single wafer.

8. The use according to claim 7, characterized in that: The GaSb single wafer polishing comprises the following steps: A) chemical mechanical polishing is performed on a GaSb single crystal wafer using a polishing cloth and the chemical mechanical polishing solution; B) Cleaning the polished GaSb single crystal wafer.

9. The use according to claim 8, characterized in that: In the step A), the GaSb single crystal is polished by a polishing machine, the polishing speed is 20 rpm to 70 rpm, and the polishing pressure is 300 g / cm 2 ~800 g / cm 2 The dripping rate of the chemical mechanical polishing liquid is 10 mL / min to 50 mL / min, and the polishing time is 5 min to 15 min; And / or, the polishing cloth in step A) is made of polyurethane; And / or, in the step B), the GaSb single crystal wafer is rinsed with deionized water and then scrubbed with ethanol, then sprayed with deionized water, and finally dried with nitrogen.

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