A chemical mechanical polishing slurry and use of the same
Patent Information
- Application Number
- TW114128007
- Authority / Receiving Office
- TW · TW
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-04-02
- Filing Date
- 2025-07-23
- Publication Date
- 2026-10-16
- Estimated Expiration
- 2045-07-22
AI Technical Summary
GaSb wafers are difficult to polish due to their reactive surface chemistry and brittleness, leading to challenges in achieving high-quality surfaces with low roughness, and existing polishing methods are complex and costly.
A chemical mechanical polishing (CMP) slurry comprising abrasive particles, polishing accelerators, an oxidant, a surfactant, a pH adjuster, and water, optimized to achieve high-quality surfaces with low roughness in a single polishing step, using a composition and content that includes inorganic and organic acid salts of alkali metals.
The CMP slurry enables efficient, one-step polishing of GaSb wafers, reducing polishing time from over 2 hours to approximately 15 minutes, achieving a smooth surface with Ra below 0.3 nm and eliminating defects like scratches and haze.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor technology, and in particular relates to a chemical mechanical polishing slurry and its uses. Prior Technology
[0002] III-V semiconductors are compound semiconductor materials formed by the combination of group III and group V elements. Commonly used group III elements include boron, aluminum, gallium, and indium, while commonly used group V elements include 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, also possessing a cubic zincblende structure. Compared to GaAs and InP, GaSb wafers have a more reactive surface chemistry and are easily oxidized. In air, a several-nanometer oxide layer can rapidly form on the surface. The passivation effect of antimony oxide and its limited solubility make chemical reactions with GaSb quite difficult.
[0003] In recent years, infrared detectors fabricated using GaSb as a substrate and epitaxial antimonide type II superlattice materials have demonstrated excellent detection performance in the long-wave and very long-wave infrared bands, showing promising application prospects in gas monitoring, night vision, and infrared imaging. The epitaxial growth of high-quality antimonide type II superlattice materials places high demands on the GaSb substrate material, requiring it to possess low defect density, high lattice integrity, and an epitaxial buffer layer with atomic-level flatness. This places high demands on the surface quality of the GaSb substrate, and its application relies on the development of polishing technology. GaSb wafers have low hardness and are brittle, making them prone to scratches; therefore, it is necessary to conduct in-depth research to solve their processing technology challenges.
[0004] To obtain high-quality GaSb material surfaces, CN116652700A provides a manual polishing method for GaSb single wafers, achieving a wafer roughness Ra below 0.70 nm. However, manual polishing is difficult to standardize and heavily relies on human factors. CN106064326B discloses a polishing method for GaSb single wafers, which results in minimal surface damage, easy cleaning, and a surface roughness of less than 0.30 nm after polishing. However, the entire polishing process is divided into coarse polishing, medium polishing, and fine polishing, and the polishing cloth, polishing fluid, and polishing parameters used are all different, making the process complex and costly. Summary of the Invention
[0005] The purpose of this invention is to provide a chemical mechanical polishing slurry and its application. The chemical mechanical polishing slurry of this invention can achieve a high-quality surface and low roughness in GaSb single crystal wafers with only one polishing step.
[0006] This invention provides a chemical mechanical polishing fluid, comprising abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH adjuster, and water; wherein... 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 the following: alkali metal carbonates, alkali metal bicarbonates, alkali metal nitrates, and alkali metal sulfates; The alkali metal organic acid salts include one or more of the following: alkali metal oxalates, alkali metal acetates, alkali metal citrates, alkali metal phthalates, and alkali metal diaminetetraacetic acids; and In this chemical mechanical polishing slurry, the mass ratio of inorganic acid salts of alkali metals to organic acid salts of alkali metals is (0.2 to 2 wt%): (0.05 to 0.5 wt%).
[0007] Preferably, the abrasive particles comprise one or more of alumina, cerium dioxide, 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 inorganic acid salt of the alkali metal includes one or more alkali metal nitrates; And / or, the alkali metal organic acid salt includes one or more of C2 to C6 alkylene or cycloalkylene diaminetetraacetic acid salts; And / or, the oxidant includes one or more of the following: bromate, bromate, chlorate, chlorite, hydrogen peroxide, hypochlorite, iodate, monoperoxysulfate, monoperoxysulfite, monoperoxyphosphate, monoperoxydiphosphate, monoperoxypyrophosphate, organic-halogen-oxygen compounds, periodate, permanganate, peracetic acid, and iron salts; And / or, the surfactant includes one or more of anionic and nonionic surfactants; And / or, the pH adjuster includes one or both of acid adjusters and base adjusters; And / or, the pH of the chemimechanical polishing solution is between 9.2 and 10.2.
[0008] Preferably, the abrasive particles comprise one or more of colloidal silica, pyrolytic silica, precipitated silica, and polycondensed silica; And / or, the average particle size of the abrasive particles is 50 to 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 organic acid salt of the alkali metal includes one or more of trans-1,2-cyclohexanediaminetetraacetate and ethylenediaminetetraacetate; And / or, the oxidant is a peroxide, including one or more of hydrogen peroxide, monoperoxysulfate, monoperoxysulfite, monoperoxyphosphate, monoperoxydiphosphate, monoperoxypyrophosphate, and peracetic acid; And / or, the surfactant includes one or more of the following: ethoxypropoxylated fatty alcohols, alkoxylated branched fatty alcohols, linear secondary alcohol polyoxyethylene ethers, polyethylene glycol stearate, sodium fatty alcohol polyoxyethylene ether sulfate, sarcosinate and taurine salts, dodecylbenzene sulfonic acid, alkyl carboxylic acid isomeric polyolamines, and acetylacetonate ethoxylated compounds; And / or, the pH adjuster is an acid adjuster, which includes one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, and oxalic acid; And / or, the pH adjuster is an alkaline adjuster, which includes one or more of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ethylenediamine, and phenylethylamine.
[0009] Preferably, the chemical mechanical polishing fluid further includes additives, which include one or more of buffers, biocides, scale inhibitors, defoamers, and dispersants.
[0010] Preferably, by weight percentage, The abrasive particles constitute 0.1 to 30 wt% of the polishing slurry. And / or, the inorganic acid salt of the alkali metal has a mass percentage content of 0.2 to 2 wt% in the polishing solution; And / or, the organic acid salt of the alkali metal in the polishing solution has a mass percentage of 0.05 to 0.5 wt%; And / or, the oxidant has a mass percentage of 0.01 to 8 wt% in the polishing slurry; And / or, the surfactant has a mass percentage content of 0.001 to 1 wt% in the polishing solution.
[0011] Preferably, by weight percentage, The abrasive particles constitute 0.2 to 25 wt% of the polishing slurry. And / or, the inorganic acid salt of the alkali metal in the polishing solution has a mass percentage of 0.2 to 1.5 wt%; And / or, the organic acid salt of the alkali metal in the polishing solution has a mass percentage of 0.05 to 0.4 wt%; And / or, the oxidant has a mass percentage of 0.02 to 5 wt% in the polishing slurry; And / or, the surfactant has a mass percentage content of 0.01 to 0.5 wt% in the polishing solution.
[0012] Preferably, the polishing fluid comprises silicon dioxide abrasive particles, potassium nitrate, trans-1,2-cyclohexanediaminetetraacetate, hydrogen peroxide, a surfactant, a pH adjuster, and water; wherein the surfactant is a linear secondary alcohol polyoxyethylene ether and / or polyethylene glycol stearate.
[0013] This invention provides the use of the chemical mechanical polishing slurry described above for polishing GaSb single wafers.
[0014] Preferably, the polishing of the GaSb single wafer includes the following steps: A) Chemical mechanical polishing (CMP) was performed on GaSb single crystal wafers using a polishing cloth and the CMP slurry. B) Clean the polished GaSb single crystal wafer.
[0015] Preferably, in step A), the GaSb single wafer is polished using a polishing machine at a polishing speed of 20 to 70 rpm, a polishing pressure of 300 to 800 g / cm2, a drop rate of the chemical mechanical polishing slurry of 10 to 50 mL / min, and a polishing time of 5 to 15 minutes; And / or, in step A), the polishing cloth is made of polyurethane; And / or, in step B), the GaSb single crystal wafer is rinsed with deionized water, then wiped with ethanol, then sprayed with deionized water, and finally dried with nitrogen.
[0016] This invention provides a chemical mechanical polishing (CMP) slurry, comprising abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH adjuster, and water. The polishing accelerator comprises inorganic acid salts and organic acid salts of alkali metals. The inorganic acid salts include one or more of alkali metal carbonates, bicarbonates, nitrates, and sulfates. The organic acid salts include one or more of oxalates, acetates, citrates, phthalates, and diaminetetraacetic acids. The mass ratio of the inorganic acid salts to the organic acid salts in the CMP slurry is (0.2 to 2 wt%):(0.05 to 0.5 wt%). This invention, through optimization of the composition and content of the polishing slurry, achieves one-step polishing of GaSb single wafers, eliminating the need for three polishing steps: rough polishing, medium polishing, and fine polishing. The process is simple, stable, and reduces the polishing time from over 2 hours to approximately 15 minutes. The GaSb single wafer obtained by the polishing method described in the above technical solution has a high-quality surface, and the surface is smooth and free from defects such as scratches, orange peel, and haze. The roughness Ra can reach below 0.3 nm. Implementation
[0017] This invention provides a chemical mechanical polishing slurry, comprising abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH adjuster, and water; wherein... 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 the following: alkali metal carbonates, alkali metal bicarbonates, alkali metal nitrates, and alkali metal sulfates; The alkali metal organic acid salts include one or more of the following: alkali metal oxalates, alkali metal acetates, alkali metal citrates, alkali metal phthalates, and alkali metal alkyl diaminetetraacetic acids; and In this chemical mechanical polishing slurry, the mass ratio of inorganic acid salts of alkali metals to organic acid salts of alkali metals is (0.2 to 2 wt%): (0.05 to 0.5 wt%).
[0018] In this invention, the chemical mechanical polishing slurry can achieve excellent polishing results for GaSb wafers, which are difficult to polish, and shorten the total polishing time. It is also applicable to the chemical mechanical polishing of compound semiconductor materials formed by the combination of group III and group V elements, such as GaAs, InP, GaSb, InAs, InSb, InAsSb, InGaAs, AlGaSb, InAlSb, AlGaAsSb, GaInAsSb, etc. However, it is not the case for other semiconductor materials. Considering the higher polishing difficulty of GaSb wafers, polishing slurries suitable for other semiconductor materials are unlikely to achieve the technical effect of the polishing slurry in this invention.
[0019] In this invention, the abrasive particles preferably include one or more of alumina, cerium dioxide, silicon dioxide, titanium dioxide, and zirconium oxide, more preferably silicon dioxide, which can be any suitable form of silicon dioxide, such as one or more of colloidal silicon dioxide, pyrolytic silicon dioxide, precipitated silicon dioxide, and polycondensed silicon dioxide; the average particle size of the abrasive particles is preferably 10 to 1000 nm, more preferably 50 to 500 nm, and even more preferably 70 to 300 nm, specifically, such as 10 nm, 30 nm, 50 nm, 70 nm, 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm, preferably a range of values with any of the above values as the upper or lower limit.
[0020] In this invention, the abrasive particles are suspended in the polishing liquid, and the mass percentage of the abrasive particles in the chemical mechanical polishing liquid is preferably 0.1% to 30%, more preferably 0.2% to 25%, such as 0.1%, 0.2%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, preferably a range of values with any of the above values as the upper or lower limit.
[0021] In this invention, the polishing accelerator can chemically react with the material being polished or combine with one of the components of the material being polished to form a substance with weak bonding or to form a bond, thereby increasing the removal rate of the material being polished; the polishing accelerator preferably includes inorganic acid salts of alkali metals and organic acid salts of alkali metals.
[0022] In this invention, the inorganic acid salt of the alkali metal includes one or more of alkali metal carbonates, alkali metal bicarbonates, alkali metal nitrates, and alkali metal sulfates; the alkali metal in the inorganic acid salt is preferably one or more of lithium, sodium, and potassium; specifically, in embodiments of this invention, the inorganic acid salt of the alkali metal can be one or more of potassium nitrate, potassium sulfate, and potassium carbonate, and the mass percentage of the inorganic acid salt of the alkali metal in the chemical mechanical polishing solution is preferably 0.2% to 2%, more preferably 0.2% to 1.5%, and even 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%, preferably a range of values with any of the above values as the upper or lower limit.
[0023] In this invention, the alkali metal organic acid salt includes one or more of alkali metal oxalates, alkali metal acetates, alkali metal citrates, alkali metal phthalates, and alkali metal diaminetetraacetic acids, more preferably one or more of C2 to C6 alkylene or cycloalkylene diaminetetraacetic acids, such as ethylenediaminetetraacetic acid and / or 1,2-cyclohexanediaminetetraacetic acid; the alkali metal in the alkali metal organic acid salt is preferably one or more of lithium, sodium, and potassium; specifically, in embodiments of this invention, the alkali metal organic acid salt may be sodium citrate, disodium ethylenediaminetetraacetate, and 1,2-cyclohexanediaminetetraacetic acid. One or more of 2-cyclohexanediaminetetraacetic acid salts; the mass percentage of the alkali metal organic acid salt in the chemical mechanical polishing slurry is preferably 0.05 to 0.5%, more preferably 0.05 to 0.4%, even 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%, preferably a range of values with any of the above values as the upper or lower limit.
[0024] In this invention, the oxidant preferably includes one or more of bromate, bromate, chlorate, chlorite, hydrogen peroxide, hypochlorite, iodate, monoperoxysulfate, monoperoxysulfite, monoperoxyphosphate, monoperoxydiphosphate, monoperoxypyrophosphate, organic-halogen-oxygen compounds, periodate, permanganate, peracetic acid, and iron salts (such as ferric nitrate); the mass percentage of the oxidant in the chemical mechanical polishing solution 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%, preferably a range of values with any of the above values as the upper or lower limit.
[0025] In this invention, the surfactant is preferably an anionic surfactant and / or a nonionic surfactant, such as one or more of ethoxypropoxylated fatty alcohols, alkoxylated branched fatty alcohols, linear secondary alcohol polyoxyethylene ethers, polyethylene glycol stearate, sodium fatty alcohol polyoxyethylene ether sulfate, sarcosinate and taurine, dodecylbenzenesulfonic acid, alkyl carboxylic acid isomeric polyolamines, and acetylenic diol ethoxylated compounds; the surfactant content in the chemical mechanical polishing solution is preferably 0.001% to 1% by mass, more preferably... The range is from 0.01% to 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 of values with any of the above values as the upper or lower limit.
[0026] In this invention, the pH adjuster preferably includes an acid adjuster and / or a base adjuster, wherein the acid adjuster is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, and oxalic acid, and the base adjuster is one or more of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ethylenediamine, and phenylethylamine; the pH value of the chemical mechanical polishing solution is preferably 9.2 to 10.2.
[0027] Depending on actual needs, the chemical mechanical polishing fluid of the present invention may further include one or more of other additives, such as buffers, biocides, scale inhibitors, defoamers, and dispersants.
[0028] The present invention does not impose any special restrictions on the preparation method of the chemical mechanical polishing fluid. It can be obtained by mixing the above-mentioned abrasive particles, polishing accelerator, oxidant, surfactant, pH adjuster and water in a conventional mixing method. In this case, the oxidant may decompose in the presence of some additives. In this case, the oxidant can be added before use.
[0029] This invention also provides an application of the aforementioned chemical mechanical polishing slurry for polishing GaSb single-wafer crystals, wherein the polishing of the GaSb single-wafer crystals includes the following steps: A) Perform chemical mechanical polishing on GaSb single-wafer crystals using the chemical mechanical polishing slurry described above; and B) Clean the polished GaSb single crystal wafer.
[0030] The present invention preferably uses a polishing cloth in conjunction with the chemical mechanical polishing slurry described above to perform chemical mechanical polishing on GaSb single crystal wafers, and before chemical mechanical polishing, the GaSb single crystal wafer to be polished is placed in a wax-free adsorption pad soaked in water for fixation.
[0031] In this invention, the polishing cloth is preferably a polyurethane polishing cloth, more preferably a black polyurethane polishing cloth; the rotation speed of the chemical mechanical polishing is preferably 20 to 70 rpm, more preferably 30 to 60 rpm, such as 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, preferably a range with any of the above values as the upper or lower limit; the pressure of the chemical mechanical polishing is preferably 300 to 800 g / cm², more preferably 400 to 700 g / cm², such as 300 g / cm², 400 g / cm², 500 g / cm², 600 g / cm², 700 g / cm², 800 g / cm², preferably a range with any of the above values as the upper or lower limit; during the chemical mechanical polishing process, the drip rate of the chemical mechanical polishing liquid is preferably 10 to 50 mL / min, more preferably 20 to 40 mL / min. The flow rate is measured in 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, or 50 mL / min, preferably within the range of values described above as the upper or lower limit. The chemical mechanical polishing time varies depending on the amount of material removed. Generally, for amounts of 5 to 20 μm, the chemical mechanical polishing time is 5 to 15 minutes, more preferably 8 to 12 minutes, such as 5 minutes, 6 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, or 15 minutes, preferably within the range of values described above as the upper or lower limit.
[0032] After completing the chemical mechanical polishing, the present invention sequentially rinses the polished GaSb single crystal with deionized water and wipes it with ethanol, then sprays it with deionized water and dries it with nitrogen to obtain the polished GaSb single crystal.
[0033] This invention provides a chemical mechanical polishing (CMP) slurry, comprising abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH adjuster, and water. The polishing accelerator comprises inorganic acid salts and organic acid salts of alkali metals. The inorganic acid salts include one or more of alkali metal carbonates, bicarbonates, nitrates, and sulfates. The organic acid salts include one or more of oxalates, acetates, citrates, phthalates, and alkyldiaminetetraacetic acids. The mass ratio of the inorganic acid salts to the organic acid salts in the CMP slurry is (0.2 to 2 wt%):(0.05 to 0.5 wt%). This invention achieves one-step polishing of GaSb single wafers by selectively optimizing the composition and content of the polishing slurry, eliminating the need for three polishing steps: rough polishing, medium polishing, and fine polishing. The process is simple, stable, and reduces the polishing time from over 2 hours to approximately 15 minutes. The GaSb single wafer obtained by the polishing method described in the above technical solution has a high-quality surface, and the surface is smooth and free from defects such as scratches, orange peel, and haze. The roughness Ra can reach below 0.3 nm.
[0034] To further illustrate the present invention, the following describes in detail the chemical mechanical polishing fluid provided by the present invention and its uses in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention. [Example] [1 pH] [right] [GaSb] [Impact of single-wafer polishing] [ ]
[0035] Chemical mechanical polishing (CMP) of GaSb single-layer wafers was performed using polishing slurries with different pH values (see Experiments 1A, 1B, and 1C in Table 1). Except for adjusting the pH to 9.1, 10.2, and 11.2 using potassium hydroxide solution, all the polishing slurries used in the experimental examples contained 20 wt% colloidal silicon dioxide, 1 wt% potassium nitrate, 0.2 wt% potassium trans-1,2-cyclohexanediaminetetraacetate, and 3 wt% hydrogen peroxide, with the remainder being deionized water. Polishing was performed using a black, grooveless polyurethane polishing pad at a speed of 50 rpm, a pressure of 25 N, and a polishing slurry flow rate of 20 mL / min. The GaSb single-layer wafer was placed in a wax-free adsorption pad soaked in deionized water and polished on a single-sided polishing machine for 5 minutes. Immediately after polishing, the GaSb single wafer was removed and rinsed with deionized water, then wiped with ethanol and dried with nitrogen. The mass change before and after polishing was compared using an electronic analytical balance with an accuracy of 0.0001 g. The removal rate of the GaSb single wafer was calculated based on the mass change. The roughness of the GaSb single wafer was obtained using atomic force microscopy (scanning range 5 x 5 μm). The experimental results are shown in Table 1.
[0036] Table 1. GaSb Removal Rate and Roughness Experimental Example pH value Removal rate (μm / min) Ra(nm) 1A 9.2 4.95 1.24 1B 10.2 4.11 1.66 1C 11.2 3.28 >2
[0037] As shown in Table 1, the roughness gradually increases with increasing pH. A high removal rate and low roughness are achieved at pH 9.2. When the pH rises to 10.2, the removal rate decreases by approximately 15%. When the pH continues to rise to 11.2, the removal rate decreases further. This indicates that for the chemical mechanical polishing of GaSb, the higher the pH, the lower the removal rate. To further verify this hypothesis, the pH was lowered to 8.2. It was found that the polishing slurry particles aggregated, leading to poor stability of the entire system. Therefore, the optimal polishing pH range for this system is 9.2 to 10.2. [Example] [2] [Oxidizing agent concentration] [GaSb] [Impact of single-wafer polishing] [ ]
[0038] Chemical mechanical polishing (CMP) of GaSb single wafers was performed using polishing slurries with different oxidant concentrations (Experiments 2A, 2B, 2C, and 2D). Except for varying concentrations of hydrogen peroxide, all the polishing slurries used in these experiments contained 20 wt% colloidal silica, 1 wt% potassium nitrate, and 0.2 wt% potassium trans-1,2-cyclohexanediaminetetraacetate. The pH was adjusted to 10.2 using potassium hydroxide, and the remaining component was deionized water. The polishing parameters and cleaning methods for the GaSb single wafers were the same as in Example 1. The mass changes before and after polishing were compared using an electronic analytical balance with an accuracy of 0.0001 g. The removal rate of the GaSb single wafers was calculated based on these mass changes. The experimental results are shown in Table 2.
[0039] Table 2. GaSb Removal Rate Experimental Example hydrogen peroxide concentration Removal rate (μm / min) Ra(nm) 2A 2wt% 3.92 1.95 2B 3wt% 4.11 1.66 2C 5wt% 2.03 >2 2D 7wt% 2.45 >2
[0040] As shown in Table 2, the removal rate increases slightly when the hydrogen peroxide concentration increases from 2 wt% to 3 wt%. When the hydrogen peroxide concentration increases to 5 wt%, the removal rate decreases by 50%. When the hydrogen peroxide concentration continues to increase to 7 wt%, the removal rate increases slightly but cannot reach the level of the 3 wt% concentration.
[0041] Furthermore, as the hydrogen peroxide concentration increased, the roughness exhibited a trend of first decreasing and then increasing, reaching its lowest point at a concentration of 3 wt%. This indicates that a hydrogen peroxide concentration of 3 wt% can achieve both a high GaSb removal rate and low roughness. [Example] [3] [Polishing Accelerator Pair] [GaSb] [Impact of single-wafer polishing] [ ]
[0042] GaSb single-crystal wafers were chemically and mechanically polished using polishing slurries containing different types of accelerators (Experiments 3A, 3B, 3C, 3D, 3E, 3F). The polishing slurries used in Examples 3A-3E all contained 20 wt% colloidal silica, 1 wt% potassium nitrate, and 3 wt% hydrogen peroxide. The pH was adjusted to 9.2 using potassium hydroxide. Except for Example 3E, which did not contain organic acid salts, Examples 3A-3D and 3G all contained 0.2% of different types of organic acid salts, with the remainder being deionized water. Furthermore, Examples 3E-3G were used to illustrate the synergistic promoting effect of potassium nitrate and organic acid salts. The polishing parameters and cleaning methods for the GaSb single-crystal wafers were the same as in Example 1. The mass change before and after polishing was compared using an electronic analytical balance with an accuracy of 0.0001 g. The removal rate of the GaSb single-crystal wafer was calculated based on the mass change. The roughness of the GaSb single-crystal wafers was obtained using atomic force microscopy (scanning range 5 x 5 μm). The experimental results are shown in Table 3.
[0043] Table 3. GaSb Removal Rate and Roughness Experimental Example Types of accelerators Potassium nitrate concentration (%) Removal rate (μm / min) Ra(nm) 3A Sodium citrate 1 1.68 1.5 3B Potassium tartrate 1 1.12 0.96 3C Disodium ethylenediaminetetraacetate 1 4.35 >2 3D Potassium trans-1,2-cyclohexanediaminetetraacetate 1 4.95 1.24 3E / 1 0.89 0.98 3F / / 0.52 1.78 3G Potassium trans-1,2-cyclohexanediaminetetraacetate / 1.27 >2
[0044] Analyzing the data in Table 3, as shown in Examples 3A-3D, different types of organic acid salts and potassium nitrate can affect the GaSb removal rate and surface roughness to varying degrees. Compared to Example 3F, Example 3E, with the addition of 1 wt% potassium nitrate alone, showed a decrease in roughness and an increase in removal rate (Rate 0.89 μm / min, a 71.15% increase compared to Example 3F). However, the improvement of surface roughness and GaSb removal rate by potassium nitrate is limited. Ideally, the amount of potassium nitrate added should not exceed 2 wt%, as further increasing the potassium nitrate content will affect the stability of the polishing slurry. Compared to Example 3F, Example 3G, with the addition of 0.2 wt% potassium trans-1,2-cyclohexanediaminetetraacetate alone, showed a significant increase in GaSb removal rate (Rate 1.27 μm / min, a 144.23% increase compared to Example 3F). Compared to Experiment 3F, Experiment 3D, which simultaneously added 1 wt% potassium nitrate and 0.2 wt% potassium trans-1,2-cyclohexanediaminetetraacetate, significantly improved the GaSb removal rate (Rate 4.95 μm / min, an increase of 851.92% compared to Experiment 3F). The effect was far greater than adding 1 wt% potassium nitrate or 0.2 wt% potassium trans-1,2-cyclohexanediaminetetraacetate alone, indicating that the two have a synergistic effect on improving the GaSb removal rate.
[0045] In summary, both inorganic acid salts and organic acid salts can accelerate the removal rate of GaSb to varying degrees. When both are present in the polishing solution, the removal rate of GaSb increases significantly, indicating that they have a synergistic effect. [Example] [4] [Surfactant pairs] [GaSb] [Impact of single-wafer polishing] [ ]
[0046] GaSb single-crystal wafers were polished using surfactants of the same concentration but different types (Examples 4A-4I). All polishing solutions contained 20 wt% colloidal silica, 1 wt% potassium nitrate, 0.2 wt% potassium trans-1,2-cyclohexanediaminetetraacetate, and 3 wt% hydrogen peroxide, with the remainder being deionized water. Except for Example 4J, which served as a comparative example and contained no surfactants, the other examples contained 0.2 wt% of different types of surfactants. The polishing parameters and cleaning methods for the GaSb single-crystal wafers were the same as in Example 1. The mass change before and after polishing was compared using an electronic analytical balance with an accuracy of 0.0001 g. The removal rate of the GaSb single-crystal wafer was calculated based on the mass change. The roughness of the GaSb single-crystal wafers was obtained using atomic force microscopy (scanning range 5 x 5 μm). The experimental results are shown in Table 4.
[0047] Table 4. GaSb Removal Rate and Roughness Experimental Example surfactants Main ingredients CAS Removal rate (μm / min) Ra(nm) 4A C8-18 Ethoxypropoxylated fatty alcohols 68603-25-8 2.04 1.1 4B CA-90 Alkoxylated branched fatty alcohols 64366-70-7 2.64 0.9 4C S-90 Linear secondary alcohol polyoxyethylene ether 84133-50-6 0.78 0.2 4D PEGMS Polyethylene glycol stearate 9004-99-3 1.61 0.5 4E AES Sodium fatty alcohol polyoxyethylene ether sulfate 9004-82-4 1.90 0.7 4F CS30 sarcosinate and taurine 61791-59-1 1.84 1.3 4G LABSA Dodecylbenzenesulfonic acid 85536-14-7 1.47 2 4H DX-NF201 Alkyl carboxylic acid isomer polyolamine / 0.25 1.2 4I SURFYNOL Acetylene diol ethoxy compounds 8043-35-4 0.17 1.7 4J / / 4.95 1.24
[0048] Table 4 shows that different types of surfactants have varying degrees of influence on the removal rate and roughness of GaSb single wafers. Experimental Example 4C / 4D exhibits good roughness (Ra≤0.5nm), and while the removal rate decreases, it still meets the requirements of the one-step GaSb polishing process. This method achieves one-step polishing of GaSb single wafers, eliminating the need for three polishing steps: roughing, intermediate polishing, and fine polishing. The process is simple, stable, and reduces the original polishing time from over 2 hours to approximately 15 minutes. Under strong light, the polished wafer surface of Experimental Example 4C / 4D is smooth, clean, and free of haze, with no scratches or particle residue. [Example] [5] Synergistic effect between polishing accelerators [ ]
[0049] Example 3 verified that the two polishing promoters, inorganic acid salts and organic acid salts, have a synergistic effect on improving the GaSb removal rate without the addition of surfactants. This example explores the effect of the two on the GaSb polishing rate when surfactants are added.
[0050] GaSb single-crystal wafers were polished using polishing accelerators of different concentrations and types (Examples 5A-5F). All examples contained 20 wt% colloidal silica, 0.2 wt% linear secondary alcohol polyoxyethylene ether, and 3 wt% hydrogen peroxide in their polishing solutions. Example 5G, as a comparative example, did not contain alkali metal inorganic salts. The other examples contained different concentrations and types of alkali metal inorganic salts and / or potassium trans-1,2-cyclohexanediaminetetraacetate. The polishing parameters and cleaning methods for the GaSb single-crystal wafers were the same as in Example 1. The mass change before and after polishing was compared using an electronic analytical balance with an accuracy of 0.0001 g. 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 atomic force microscopy (scanning range 5x5 μm). The experimental results are shown in Table 4.
[0051] Table 5. GaSb Removal Rate and Roughness Experimental Example Alkali metal inorganic salts Alkali metal inorganic salt concentration (%) potassium trans-1,2-cyclohexanediaminetetraacetate concentration (%) Removal rate ( μm / min ) Ra(nm) 5A potassium nitrate 0.5 0.2 0.41 >2 5B potassium nitrate 1 0.2 0.78 0.2 5C potassium nitrate 2 0.2 0.84 0.5 5D potassium sulfate 1 0.2 0.53 >2 5E Potassium carbonate 1 0.2 0.69 >2 5F potassium nitrate 1.2 / 0.44 >2 5G / / 0.5 0.32 >2
[0052] Analyzing the data in Table 5, in Experiment 5F, the polishing accelerator was 1.2 wt% potassium nitrate, resulting in a GaSb removal rate of 0.44 μm / min and a roughness >2 nm. In Experiment 5G, the polishing accelerator was 0.5 wt% potassium trans-1,2-cyclohexanediaminetetraacetate, resulting in a GaSb removal rate of 0.32 μm / min and a roughness >2 nm. Further increasing the content of organic acid salts did not further increase the GaSb removal rate; instead, it affected the stability of the polishing solution. Therefore, the optimal addition amount of organic acid salts should not exceed 0.5%. In Experiment 5B, the polishing accelerator was 1 wt% potassium nitrate and 0.2 wt% potassium trans-1,2-cyclohexanediaminetetraacetate, resulting in a GaSb removal rate of 0.78 μm / min and a roughness of 0.2 nm. While the roughness decreased significantly, the GaSb removal rate increased significantly, which was significantly better than in Experiments 5F and 5G, indicating a synergistic effect between organic and inorganic acid salts.
[0053] The different removal rates and roughnesses of Experiments 5B, 5D, and 5E indicate that the synergistic effects of different types of inorganic acid salts and the same type of organic acid salt are not entirely the same. Experiment 5B achieved a higher removal rate while maintaining a lower roughness. Under strong light, the polished wafer surface of Experiment 5B was observed to be smooth, clean, and free of haze, with no scratches or particle residue. In Experiments 5D and 5E, the polished GaSb was difficult to clean completely, leaving more particles on the surface, resulting in higher roughness.
[0054] The results of Experiments 5A-5C show that different potassium nitrate concentrations have a significant impact on the removal rate and roughness of GaSb. As the potassium nitrate concentration increases, the removal rate of GaSb gradually increases. However, compared with Experiment 5B, the roughness of GaSb after polishing in Experiment 5C is higher, and the polishing solution is in poor condition, easily exhibiting stratification. Therefore, the potassium nitrate content should not exceed 2 wt%.
[0055] 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 considered within the scope of protection of the present invention.
Claims
1. A chemical mechanical polishing (CMP) slurry, comprising abrasive particles, a polishing accelerator, an oxidant, a surfactant, a pH adjuster, and water; wherein the polishing accelerator comprises inorganic acid salts and organic acid salts of alkali metals; the inorganic acid salts of alkali metals comprise one or more of alkali metal carbonates, alkali metal bicarbonates, alkali metal nitrates, and alkali metal sulfates; the organic acid salts of alkali metals comprise one or more of alkali metal oxalates, alkali metal acetates, alkali metal citrates, alkali metal phthalates, and alkali metal diaminetetraacetic acid salts; and the pH of the CMP slurry is 9.2 to 10.2; the abrasive particles constitute 0.1 to 30 wt% of the CMP slurry by mass percentage; the inorganic acid salts of alkali metals constitute 0.2 to 2 wt% of the CMP slurry by mass percentage; and the organic acid salts of alkali metals constitute 0.05 to 0.5 wt% of the CMP slurry by mass percentage. The oxidant has a mass percentage content of 0.01 to 8 wt% in the chemical mechanical polishing slurry; the surfactant has a mass percentage content of 0.001 to 1 wt% in the chemical mechanical polishing slurry.
2. The chemical mechanical polishing slurry as claimed in claim 1, wherein the abrasive particles comprise one or more of alumina, cerium dioxide, 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 inorganic acid salt of the alkali metal comprises one or more of alkali metal nitrates; and / or, the organic acid salt of the alkali metal comprises one or more of C2 to C6 alkylene or cycloalkylene diaminetetraacetic acid salts; and / or, the oxidant comprises one or more of bromate, bromate, chlorate, chlorite, hydrogen peroxide, hypochlorite, iodate, monoperoxysulfate, monoperoxysulfite, monoperoxyphosphate, monoperoxydiphosphate, monoperoxypyrophosphate, organic-halogen-oxygen compounds, periodate, permanganate, peracetic acid, and iron salts; and / or, the surfactant comprises one or more of anionic and nonionic surfactants. And / or, the pH adjuster includes one or both of acid adjusters and base adjusters.
3. The chemical mechanical polishing slurry as claimed in claim 1, wherein the abrasive particles comprise one or more of colloidal silica, pyrolytic silica, precipitated silica, and condensed silica; and / or, the average particle size of the abrasive particles is 50 to 500 nm; and / or, the inorganic acid salt of the alkali metal comprises one or both of potassium nitrate and sodium nitrate; and / or, the organic acid salt of the alkali metal comprises one or more of trans-1,2-cyclohexanediaminetetraacetate and ethylenediaminetetraacetate; and / or, the oxidant is a peroxide, the peroxide comprising one or more of hydrogen peroxide, monoperoxysulfate, monoperoxysulfite, monoperoxyphosphate, 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 stearate, sodium fatty alcohol polyoxyethylene ether sulfate, sarcosinate and taurine, dodecylbenzenesulfonic acid, alkyl carboxylic acid isomeric polyolamines, and ethynyldiol ethoxylated compounds; and / or, the pH adjuster is an acid adjuster, comprising one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, and oxalic acid; and / or, the pH adjuster is a base adjuster, comprising one or more of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ethylenediamine, and phenylethylamine.
4. The chemical mechanical polishing fluid as claimed in claim 1, further comprising additives, including one or more of buffers, biocides, scale inhibitors, defoamers, and dispersants.
5. The chemical mechanical polishing slurry as described in claim 1, wherein, The abrasive particles constitute 0.2 to 25 wt% of the chemical mechanical polishing slurry by mass percentage; and / or, the inorganic acid salt of the alkali metal constitutes 0.2 to 1.5 wt% of the chemical mechanical polishing slurry by mass percentage; and / or, the organic acid salt of the alkali metal constitutes 0.05 to 0.4 wt% of the chemical mechanical polishing slurry by mass percentage; and / or, the oxidant constitutes 0.02 to 5 wt% of the chemical mechanical polishing slurry by mass percentage; and / or, the surfactant constitutes 0.01 to 0.5 wt% of the chemical mechanical polishing slurry by mass percentage.
6. The chemical mechanical polishing slurry as described in claim 1, wherein, The chemical mechanical polishing slurry comprises silicon dioxide abrasive particles, potassium nitrate, trans-1,2-cyclohexanediaminetetraacetate, hydrogen peroxide, the surfactant, the pH adjuster, and water; wherein the surfactant is linear secondary alcohol polyoxyethylene ether and / or polyethylene glycol stearate.
7. Use of a chemical mechanical polishing slurry as described in any one of claims 1 to 6 for polishing GaSb single wafers.
8. The use as described in claim 7, wherein, The polishing of the GaSb single crystal wafer includes the following steps: A) performing chemical mechanical polishing on the GaSb single crystal wafer using a polishing cloth and the chemical mechanical polishing slurry; and B) cleaning the polished GaSb single crystal wafer.
9. The use as described in claim 8, wherein in step A), the GaSb single wafer is polished using a polishing machine at a polishing speed of 20 to 70 rpm, a polishing pressure of 300 to 800 g / cm², a chemical mechanical polishing slurry dripping rate of 10 to 50 mL / min, and a polishing time of 5 to 15 minutes; and / or, in step A), the polishing cloth is made of polyurethane; and / or, in step B), the GaSb single wafer is rinsed with deionized water, then wiped with ethanol, then sprayed with deionized water, and finally dried with nitrogen.