A composite material, its preparation method and use in chemical mechanical polishing slurries

Abstract

This application discloses a composite material, its preparation method, and its application in chemical mechanical polishing slurries. The composite material includes modified nano-silica and a metal-organic polymer grown on the surface of the modified nano-silica; the particle size is 30–120 nm; the metal element is selected from at least one of Fe, Co, Ni, Cu, Zn, Mn, Zr, and Al; the organic ligand is selected from at least one of formic acid, acetic acid, propionic acid, oxalic acid, butyric acid, malonic acid, succinic acid, citric acid, fumaric acid, terephthalic acid, 2,5-furandicarboxylic acid, nicotinic acid, and isonicotinic acid. Anchoring metal ions on the surface of the abrasive particles in the form of a metal-organic polymer facilitates the coupling between chemical reactions and mechanical grinding during chemical mechanical polishing; it also helps alleviate the problem of residual metal ions after polishing, preventing them from affecting the electrical performance of devices and effectively improving product yield.

Description

Technical Field

[0001] This application relates to a composite material, its preparation method, and its application in chemical mechanical polishing slurry, and belongs to the field of materials. Background Technology

[0002] With the continuous development of semiconductor technology, the geometric dimensions of devices in integrated circuits are constantly shrinking. More components can be manufactured on a limited wafer surface, thus requiring a sufficient number of metal interconnects on the wafer surface to connect the devices. During chip manufacturing, the formation of new layers creates an uneven surface, necessitating planarization. Chemical mechanical polishing (CMP) is the best method for achieving global planarization and one of the most important processes in chip manufacturing. CMP technology was pioneered by IBM in the 1980s. Its basic principle is the synergistic effect of chemical reaction and mechanical grinding to achieve global planarization. In CMP, the wafer is fixed to a polishing head and brought into contact with a polishing pad. Under a certain external force, the wafer moves relative to the polishing head and pad. Simultaneously, polishing slurry is continuously injected and spread onto the surface of the polishing pad under centrifugal force. The wafer material is removed through the combined action of chemical reaction and mechanical grinding. Among them, the chemical reaction is the reaction between the wafer surface and the polishing slurry, which causes a softening layer to form on the wafer surface. Mechanical polishing refers to the mechanical action between the abrasive particles in the polishing slurry and the wafer surface, which removes the softening layer on the wafer surface. This process is repeated until global planarization is achieved.

[0003] Tungsten metal exhibits good resistance to electron migration at high current densities and can form good ohmic contacts with silicon, making it commonly used as a plug in chips to connect multilayer structures. Typically, an interlayer dielectric material is deposited and etched onto a semiconductor substrate, followed by the deposition of an adhesion layer in the vias, and then tungsten metal is deposited onto the vias and adhesion layer. However, the surface of the deposited tungsten metal layer is not perfectly flat, which is detrimental to subsequent processes; therefore, planarization is necessary.

[0004] Because tungsten has a high hardness (Mohs hardness 7.5), in the CMP process of tungsten, it is first oxidized into a soft oxide layer through a chemical reaction, and then subjected to a subsequent mechanical grinding process. The mutual coupling between the two processes achieves the global planarization of tungsten. US Patent 5958288 discloses a chemical mechanical polishing method for tungsten using Fe(NO3)3 as a catalyst and hydrogen peroxide as an oxidant. Metal ions catalyze the decomposition reaction of oxidants (hydrogen peroxide, persulfate, etc.) to generate free radicals with strong oxidizing properties. The tungsten is softened by the reaction of the oxidizing free radicals with the tungsten (J. Electrochem. Soc., 1991, 138(11):3460.). Taking the Fenton reaction as an example, the reaction equation for the oxidation of tungsten is as follows:

[0005] Fe 2+ +H₂O₂→Fe 3+ +·OH+OH - (1)

[0006] Fe 3+ +H₂O₂→Fe 2+ +·O2H+H + (2)

[0007] W + 6·OH → WO3 + 3H2O (3)

[0008] The WO3 generated by the above reaction is soft and can be rapidly removed by the abrasive particles, thus achieving global planarization. Metal ions are typically introduced as catalysts into tungsten polishing slurries to catalyze the oxidation of tungsten by the oxidant, accelerating the corrosion rate of tungsten. However, residual gold ions can affect the electrical performance of the chip, causing short circuits, leakage, and other problems, thereby reducing the yield of chip products. Furthermore, the introduction of metal ions complicates the cleaning process after polishing.

[0009] This patent application introduces metal ions onto the surface of abrasive particles, promoting the immobilization and nanoscale dispersion of the metal ion catalyst, thereby achieving an "integrated" coupling of chemical reaction and mechanical grinding, and enhancing free radical transport and tungsten oxidation during the polishing process. In the CMP process, the metal ion organic polymer acts as a catalyst, uniformly dispersed onto the surface of the polishing pad along with the abrasive particles. The free radicals generated by the decomposition of the catalytic oxidant react with the tungsten wafer surface, oxidizing it (J. Electrochem. Soc., 1991, 138(11): 3460.). Subsequently, under the mechanical action of the abrasive particles, the oxide layer is removed, and the exposed metal layer is oxidized again. This process repeats until global planarization is achieved. The metal ion organic polymer loaded onto the surface of the abrasive particles is removed along with the particles, effectively alleviating the problem of residual metal ions on the wafer surface, thereby reducing product leakage and short circuits, and improving product yield. Therefore, anchoring the metal ion catalyst onto the surface of the abrasive particles to achieve an "integrated" coupling of chemical reaction and mechanical grinding is of great significance. Summary of the Invention

[0010] The purpose of this invention is to provide a nano-silica metal-organic polymer composite material for chemical mechanical polishing of tungsten metal. This composite material facilitates the coupling effect between chemical reaction and mechanical grinding, and is suitable for tungsten chemical mechanical polishing processes in the chip manufacturing field.

[0011] Another objective of this invention is to provide abrasive particles of composite materials that facilitate the integration of chemical reaction and mechanical grinding, effectively alleviate the problem of residual catalyst metal ions after polishing, and are suitable for chemical mechanical polishing of tungsten metal.

[0012] According to one aspect of this application, a composite material is provided, comprising modified nano-silica and a metal-organic polymer grown on the surface of said modified nano-silica;

[0013] The particle size of the composite material is 30–120 nm;

[0014] The metal element in the organometallic polymer is selected from at least one of Fe, Co, Ni, Cu, Zn, Mn, Zr, and Al;

[0015] The organic ligand of the organometallic polymer is selected from at least one of formic acid, acetic acid, propionic acid, oxalic acid, butyric acid, malonic acid, succinic acid, citric acid, fumaric acid, terephthalic acid, 2,5-furandicarboxylic acid, nicotinic acid, and isonicotinic acid.

[0016] Optionally, the particle size of the composite material is 40–100 nm.

[0017] According to another aspect of this application, a method for preparing the aforementioned composite material is provided. This method involves modifying nano-silica with a coupling agent and an anhydride, and then further growing a metal-organic polymer on the modified nano-silica surface by adding organic ligands and metal ions, thereby obtaining a nano-silica metal-organic polymer composite material. This nano-silica metal-organic polymer composite material facilitates the integration of chemical reaction and mechanical grinding, and is suitable for the chemical mechanical polishing process of tungsten metal in the chip manufacturing field. The reaction mechanism between the coupling agent and the anhydride involves the reaction of primary amines with the anhydride to form amide bonds. The modification mechanism of the nano-silica involves a condensation reaction between the coupling agent and the silanol groups on the surface of the nano-silica, causing the coupling agent to bond to the surface of the nano-silica.

[0018] Includes the following steps:

[0019] The raw materials containing modified nano-silica, metal salt, and organic ligand are mixed and stirred to obtain the composite material.

[0020] The metal salt is selected from at least one of the nitrate, sulfate, chloride, carbonate, and acetate salts of the metal element;

[0021] The mass ratio of the metal salt to the organic ligand is 1:0.1 to 10;

[0022] The mass ratio of the metal salt to the modified nano-silica is 1:100 to 10000.

[0023] The modified nano-silica is obtained through the following steps:

[0024] The coupling agent precursor, acid anhydride, and solvent are mixed to obtain the coupling agent. The coupling agent is then mixed with nano-silica, heated, and stirred to obtain modified nano-silica.

[0025] The nano-silica is selected from silica sol or fumed silica;

[0026] The particle size of the nano-silica is 20–100 nm;

[0027] The coupling agent precursor is selected from at least one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, and N-2-aminoethyl-3-aminopropyltriethoxysilane.

[0028] The acid anhydride is selected from at least one of succinic anhydride, glutaric anhydride, maleic anhydride, and phthalic anhydride;

[0029] The solvent is selected from at least one of methanol, ethanol, ethylene glycol, propanol, N,N-dimethylformamide, and N,N-dimethylacetamide;

[0030] The molar ratio of the coupling agent precursor to the acid anhydride is 1:0.1 to 10;

[0031] The molar ratio of the coupling agent precursor to the solvent is 1:10 to 1000;

[0032] The heating temperature is 60–120°C;

[0033] The stirring speed of the stirring b is 100-400 rpm;

[0034] The stirring time for step b is 6 to 20 hours.

[0035] The stirring speed of the stirring a is 200-400 rpm;

[0036] The stirring time is 6 to 20 hours.

[0037] According to another aspect of this application, a chemical mechanical polishing slurry is provided, comprising the aforementioned composite material, oxidant, pH adjuster, and water.

[0038] The oxidant is selected from at least one of hydrogen peroxide, persulfate, potassium permanganate, and peracetic acid;

[0039] The pH adjuster is selected from at least one of dilute nitric acid, dilute hydrochloric acid, and dilute sulfuric acid.

[0040] In the chemical mechanical polishing slurry, the mass content of the composite material is 0.1-10 wt%; optionally, in the chemical mechanical polishing slurry, the mass content of the composite material is 0.5-5 wt%.

[0041] Optionally, in the chemical mechanical polishing slurry, the mass content of the composite material is 0.5 to 3 wt%.

[0042] In the chemical mechanical polishing slurry, the oxidant has a mass content of 0.1–10 wt%.

[0043] Optionally, the oxidant in the chemical mechanical polishing slurry has a mass content of 1-5 wt%.

[0044] Optionally, the oxidant in the chemical mechanical polishing slurry has a mass content of 1-3%;

[0045] The pH of the chemical mechanical polishing slurry is 1 to 4.

[0046] Optionally, the pH of the chemical mechanical polishing slurry is 2 to 3.

[0047] According to another aspect of this application, an application of the above-described chemical mechanical polishing slurry is provided for use in the chemical mechanical polishing process of tungsten metal.

[0048] The beneficial effects that this application can produce include:

[0049] 1) Anchoring metal ions on the surface of abrasive particles in the form of metal-organic polymers is beneficial for achieving the coupling between chemical reactions and mechanical grinding during chemical mechanical polishing.

[0050] 2) The application of nano-silica metal-organic polymer composite materials helps to alleviate the problem of residual metal ions after polishing, avoids them from affecting the electrical performance of the device, and effectively improves the product yield. Attached Figure Description

[0051] Figure 1 This is a TEM image of the nano-silica metal-organic polymer composite material in Example 1 of this application, with a scale of 100 nm.

[0052] Figure 2 This is a TEM image of the nano-silica metal-organic polymer composite material in Example 1 of this application, with a scale of 20 nm.

[0053] Figure 3 The polishing rate test results of the nano-silica metal-organic polymer composite materials in Examples 1 and 2 and Comparative Examples 1 and 2 of this application are shown. Detailed Implementation

[0054] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0055] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0056] The analysis method in the embodiments of this application is as follows:

[0057] CMP experiments were conducted using a UMT-Tribolab polishing machine (Bruker Corporation, USA) and polyurethane polishing pads (Sub400 & IC1000, Dow Electronic Materials, USA).

[0058] The thickness of tungsten wafers was measured using an RTS-9 dual-electric four-probe tester.

[0059] The zeta potential, conductivity, particle size, and particle size distribution index were measured using a Malvern Zeta-sizer Nano instrument (Nano-ZS90, Thermo Fisher Scientific, USA).

[0060] TEM testing was performed using JEM-2100.

[0061] According to embodiments of this application, a method for preparing a nano-silica metal-organic polymer composite material is provided. The method is characterized by introducing the metal-organic polymer onto the surface of nano-silica, achieving an integrated process of chemical reaction and mechanical grinding. This alleviates the problem of residual metal ions after polishing, prevents them from affecting the electrical properties of the product, and effectively improves the product yield. The specific implementation steps are as follows:

[0062] A chemical mechanical polishing slurry for tungsten metal comprises 0.5-5% by mass of a nano-silica organometallic polymer, 1-5% by mass of an oxidant, and the balance being water. Preferably, the chemical mechanical polishing slurry for tungsten metal comprises 0.5-3% by mass of a nano-silica organometallic polymer, 1-3% by mass of an oxidant, and the balance being water.

[0063] Example 1

[0064] 0.9 g of aminopropyl-3-ethoxysilane, 0.203 g of succinic anhydride, and 30 g of anhydrous ethanol were placed in a beaker and shaken for 12 h to allow the reaction to proceed fully, yielding mixture a. Mixture a was then mixed with silica sol with a particle size of 75 nm to obtain 180 g of mixture b, wherein the mass fraction of nano-silica was 5%. This mixture was heated at 80 °C for 24 h to obtain modified silica sol. The modified silica sol was washed through an ultrafiltration membrane. A certain amount of the modified silica sol was then added to Fe(NO3)3 and sodium acetate solution to prepare mixture c, wherein the content of nano-silica was 1%, and Fe... 3+ Content 90 ppm, sodium acetate and Fe 3+ The molar ratio was 4:1, and the mixture was stirred at room temperature for 24 hours to obtain a nano-silica metal-organic polymer composite material.

[0065] Figure 1 This is a TEM image of the nano-silica metal-organic polymer composite material in Example 1 of this application, with a scale of 100 nm.

[0066] Figure 2 This is a TEM image of the nano-silica metal-organic polymer composite material in Example 1 of this application, with a scale of 20 nm.

[0067] from Figure 1 , Figure 2It can be seen that the prepared nano-silica composite material has a uniform particle size distribution, all maintained at around 80 nm, and the surface of the nano-silica is uniformly coated with a layer of metal-organic polymer, with a shell thickness ranging from 1 to 10 nm.

[0068] The chemical mechanical polishing properties of the above materials were tested using tungsten metal:

[0069] A polishing solution was prepared, comprising 1% by mass of nano-silica metal-organic polymer, 2% by mass of hydrogen peroxide, and a pH of 2.5.

[0070] Polishing process parameters: polishing pressure 2psi, polishing time 1min, polishing fluid flow rate 80ml / min, polishing head speed 65rpm, polishing pad speed 60rpm.

[0071] Example 2

[0072] 0.9 g of aminopropyl-3-ethoxysilane, 0.203 g of succinic anhydride, and 30 g of anhydrous ethanol were placed in a beaker and shaken for 12 h to allow the reaction to proceed fully, yielding mixture a. Mixture a was then mixed with silica sol with a particle size of 100 nm to obtain 180 g of mixture b, wherein the mass fraction of nano-silica was 5%. This mixture was heated at 80 °C for 24 h to obtain modified silica sol. The modified silica sol was washed through an ultrafiltration membrane. A certain amount of the modified silica sol was then added to Fe(NO3)3 and sodium acetate solution to prepare mixture c, wherein the content of nano-silica was 1%, and Fe... 3+ Content 90 ppm, sodium acetate and Fe 3+ The molar ratio was 4:1, and the mixture was stirred at room temperature for 24 hours to obtain a nano-silica metal-organic polymer composite material.

[0073] The obtained material was characterized and was similar to that of Example 1.

[0074] The chemical mechanical polishing properties of the above materials were tested using tungsten metal:

[0075] A polishing solution was prepared, comprising 1% by mass of nano-silica metal-organic polymer, 2% by mass of hydrogen peroxide, and a pH of 2.5.

[0076] Polishing process parameters: polishing pressure 2psi, polishing time 1min, polishing fluid flow rate 80ml / min, polishing head speed 65rpm, polishing pad speed 60rpm.

[0077] Comparative Example 1

[0078] Chemical mechanical polishing performance test of tungsten metal:

[0079] The polishing slurry was prepared, containing 1% by mass of 75nm nano-sized silicon dioxide and Fe. 3+It contains 30 ppm of hydrogen peroxide (2% by mass) and has a pH of 2.5.

[0080] Polishing process parameters: polishing pressure 2psi, polishing time 1min, polishing fluid flow rate 80ml / min, polishing head speed 65rpm, polishing pad speed 60rpm.

[0081] Comparative Example 2

[0082] Chemical mechanical polishing performance test of tungsten metal:

[0083] The polishing slurry was prepared, containing 3% by mass of 75nm nano-sized silicon dioxide and Fe. 3+ It contains 30 ppm of hydrogen peroxide (2% by mass) and has a pH of 2.5.

[0084] Polishing process parameters: polishing pressure 2psi, polishing time 1min, polishing fluid flow rate 80ml / min, polishing head speed 65rpm, polishing pad speed 60rpm.

[0085] Figure 3 The polishing rate test results of the nano-silica metal-organic polymer composite materials in Examples 1 and 2 and Comparative Examples 1 and 2 of this application are shown.

[0086] Table 1 shows the chemical mechanical polishing test results of tungsten metal and the physicochemical properties of the polishing solution.

[0087] Table 1

[0088]

[0089] A nano-silica metal-organic polymer composite material with uniform particle size distribution was successfully prepared by surface modification treatment of nano-silica and growth of metal-organic polymers. This composite material exhibited excellent performance in the chemical mechanical polishing (CMP) of tungsten. It directionally introduces metal ions onto the surface of abrasive particles, thereby achieving an "integrated" process of chemical reaction and mechanical polishing, promoting their coupling. Simultaneously, the material effectively alleviates the problem of residual metal ions after polishing, significantly improving product yield.

[0090] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A composite material, characterized in that, Includes modified nano-silica and a metal-organic polymer grown on the surface of the modified nano-silica; The metal element in the organometallic polymer is selected from at least one of Fe, Co, Ni, Cu, Zn, Mn, Zr, and Al; The organic ligand of the metal-organic polymer is selected from at least one of formic acid, acetic acid, propionic acid, oxalic acid, butyric acid, malonic acid, succinic acid, citric acid, fumaric acid, terephthalic acid, 2,5-furandicarboxylic acid, nicotinic acid, and isonicotinic acid. The modified nano-silica is obtained through the following steps: The coupling agent precursor, acid anhydride, and solvent are mixed to obtain the coupling agent. The coupling agent is then mixed with nano-silica, heated, and stirred to obtain modified nano-silica. The nano-silica is selected from silica sol or fumed silica; The particle size of the nano-silica is 20~100nm; The coupling agent precursor is selected from at least one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, and N-2-aminoethyl-3-aminopropyltriethoxysilane. The acid anhydride is selected from at least one of succinic anhydride, glutaric anhydride, maleic anhydride, and phthalic anhydride; The solvent is selected from at least one of methanol, ethanol, ethylene glycol, propanol, N,N-dimethylformamide, and N,N-dimethylacetamide; The molar ratio of the coupling agent precursor to the acid anhydride is 1:0.1~10; The molar ratio of the coupling agent precursor to the solvent is 1:10~1000; The heating temperature is 60~120℃; The stirring speed of the stirring b is 100~400 rpm; The stirring time for step b is 6 to 20 hours.

2. The composite material according to claim 1, characterized in that, The particle size of the composite material is 30~120nm.

3. The composite material according to claim 1, characterized in that, The particle size of the composite material is 40~100nm.

4. A method for preparing the composite material according to any one of claims 1 to 3, characterized in that, Includes the following steps: The raw materials containing modified nano-silica, metal salt, and organic ligand are mixed and stirred to obtain the composite material.

5. The preparation method according to claim 4, characterized in that, The metal salt is selected from at least one of the nitrate, sulfate, chloride, carbonate, and acetate salts of the metal element; The mass ratio of the metal salt to the organic ligand is 1:0.1~10; The mass ratio of the metal salt to the modified nano-silica is 1:100~10000.

6. The preparation method according to claim 4, characterized in that, The stirring speed of the agitator is 200~400 rpm; The stirring time is 6~20h.

7. A chemical mechanical polishing slurry, characterized in that, Contains the composite material, oxidant, pH adjuster, and water as described in any one of claims 1 to 3; The oxidant is selected from at least one of hydrogen peroxide, persulfate, potassium permanganate, and peracetic acid; The pH adjuster is selected from at least one of dilute nitric acid, dilute hydrochloric acid, and dilute sulfuric acid.

8. The chemical mechanical polishing slurry according to claim 7, characterized in that, In the chemical mechanical polishing slurry, the mass content of the composite material is 0.1~10 wt%; In the chemical mechanical polishing slurry, the oxidant has a mass content of 0.1~10 wt%; The pH of the chemical mechanical polishing slurry is 1-4.

9. The application of a chemical mechanical polishing slurry according to any one of claims 7 or 8, characterized in that, Chemical mechanical polishing process for tungsten metal.

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