Surfactant, chemical mechanical polishing composition for tungsten and polishing method

Abstract

The invention discloses a surfactant which is a quaternary ammonium salt type cationic surfactant, the structural formula of a cationic part of the surfactant is # imgabs0, and R1-R11 independently comprise one or a combination of more of methyl, alkyl with the carbon atom number of 12-16, paraxylylene, alkenyl, benzyl, hydroxyl, heterocyclic radical, carboxyl and amino. The invention also discloses a chemical mechanical polishing composition containing the surfactant and a method for polishing a substrate containing tungsten, so that the EOE1 caused by too high tungsten corrosion rate is reduced, the surface of a tungsten plug and an interlayer insulating dielectric layer beside the tungsten plug are completely flattened, the tungsten plug is prevented from being sunken, and the service life of the tungsten plug is prolonged. Subsequent multilayer metal interconnection is easy to carry out, and improvement of device contact interconnection performance and improvement of integrated circuit density are facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a surfactant, a chemical mechanical polishing composition for tungsten containing the surfactant, and a polishing method. Background Art

[0002] With the rapid development of modern machining technology and electronic information technology, various mechanical components and electronic components have achieved amazing development and tend to be of high performance. High-performance integrated circuits have put forward higher and higher requirements for the processing accuracy such as surface roughness and flatness of some key parts. In semiconductor manufacturing processes, in order to better meet the high requirements of lithography for planarization, chemical mechanical polishing process (CMP) has been widely used in deep sub-micron technology (<0.25um).

[0003] The chemical mechanical polishing technology of tungsten is one of the key new processes in the development of deep sub-micron CMOS integrated circuits. Tungsten metal is widely used in multi-layer metal interconnection technology due to its excellent anti-electromigration performance and easy processing characteristics. Using tungsten chemical mechanical polishing to replace the reactive ion etching back-etching method can completely planarize the surface of tungsten plugs and the adjacent interlayer dielectric layer, avoid the phenomenon of tungsten plug depression, make the subsequent multi-layer metal interconnection easier, and is beneficial to improving the device contact interconnection performance and increasing the integrated circuit density.

[0004] Edge corrosion is generally a phenomenon that occurs after CMP. In the application of tungsten metal polishing, this phenomenon may be more serious. As the device size shrinks for more advanced applications, the performance requirements for CMP become more and more stringent, and reducing or even eliminating the edge corrosion phenomenon has become the main concern in CMP.

[0005] There is an urgent need to explore a new chemical mechanical polishing composition for tungsten to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of the problems existing in the prior art, in the first aspect, the present invention provides a surfactant, which is a quaternary ammonium salt type cationic surfactant, and the structural formula of its cation part is

[0007]

[0008] wherein, R1 to R 11 each independently includes one or more combinations of methyl, an alkyl group with 12 to 16 carbon atoms, p-phenylenedimethylene, alkenyl, benzyl, hydroxyl, heterocyclic group, carboxyl, and amino;

[0009] Furthermore, the cation part of the quaternary ammonium salt type cationic surfactant is one or more combinations of the following structural formulas:

[0010]

[0011] Further, the cationic part of the quaternary ammonium salt type cationic surfactant is one or a combination of two of the following structural formulas:

[0012]

[0013] In a second aspect of the present invention, a chemical mechanical polishing composition for tungsten is provided. The chemical mechanical polishing composition for tungsten comprises 0.5 - 5.0 wt% of abrasive particles, a catalyst, a chelating agent, a corrosion inhibitor, 0.01 - 0.2 wt% of the surfactant as described in the first aspect of the present invention, a bactericide and an oxidizing agent;

[0014] The pH of the chemical mechanical polishing composition for tungsten is 2 - 7;

[0015] Further, the chemical mechanical polishing composition for tungsten comprises 1.0 - 3.0 wt% of abrasive particles, a catalyst, a chelating agent, a corrosion inhibitor, 0.05 - 0.1 wt% of the surfactant as described in the first aspect of the present invention, a bactericide and an oxidizing agent;

[0016] The pH of the chemical mechanical polishing composition for tungsten is 3 - 5;

[0017] Further, the chelating agent comprises one or a combination of malonic acid, citric acid, maleic acid;

[0018] Preferably, the chelating agent is malonic acid;

[0019] Further, the abrasive particles comprise one or a combination of silica, cerium oxide, alumina.

[0020] Further, the abrasive particles are silica, the average particle size of the silica is 40 - 80 nm, and the Zeta potential of the silica is 15 - 55 mV;

[0021] Further, the catalyst comprises one or a combination of iron nitrate, iron sulfate, iron chloride, iron bromide;

[0022] Preferably, the catalyst is iron nitrate;

[0023] The corrosion inhibitor comprises one or a combination of lysine, arginine, proline;

[0024] Preferably, the corrosion inhibitor comprises one or a combination of lysine and arginine;

[0025] The fungicide includes one or a combination of more than one of methylisothiazolinone, 5-chloro-2-methyl-4-isothiazolin-3-one, and 1,2-benzisothiazolin-3-one;

[0026] Preferably, the fungicide is 5-chloro-2-methyl-4-isothiazolin-3-one;

[0027] The oxidant includes one or a combination of more than one of hydrogen peroxide, persulfate, and periodate;

[0028] Preferably, the oxidant is hydrogen peroxide;

[0029] The third aspect of the present invention provides a method for polishing a substrate, including:

[0030] (i) Providing a substrate containing tungsten;

[0031] (ii) Providing a polishing pad;

[0032] (iii) Providing a chemical mechanical polishing composition as described in the second aspect of the present invention;

[0033] (iv) Bringing the substrate into contact with the polishing pad and the chemical mechanical polishing composition; and

[0034] (v) Moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to grind at least a part of the substrate to polish the substrate.

[0035] Beneficial effects:

[0036] The present invention proposes a surfactant and a chemical mechanical polishing composition for tungsten containing the same. Using this chemical mechanical polishing composition, the EOE (edge over-etching) caused by too fast tungsten corrosion rate is reduced, the surface of the tungsten plug and the adjacent interlayer dielectric layer are completely flattened, the phenomenon of tungsten plug depression is avoided, the subsequent multi-layer metal interconnection is facilitated, and it is beneficial to improve the device contact interconnection performance and increase the integrated circuit density. Specific embodiments

[0037] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] <Surfactant>

[0039] In the present invention, the surfactant is a quaternary ammonium salt type cationic surfactant, and the structural formula of its cation part is

[0040]

[0041] Among them, R1 to R 11 Each independently includes one or more combinations of methyl, an alkyl group with 12 to 16 carbon atoms, p-phenylenedimethylene, alkenyl, benzyl, hydroxyl, heterocyclic group, carboxyl, and amino.

[0042] In the present invention, preferably, the cationic part of the quaternary ammonium salt type cationic surfactant is one or more combinations of the structural formulas shown in the following figure:

[0043]

[0044] In the present invention, the quaternary ammonium salt type cationic surfactant can be obtained commercially or synthesized by conventional methods. Examples of the conventional methods include steps such as heating and stirring, cooling and crystallization, filtration, and recrystallization. The operation is simple and suitable for industrial production.

[0045] More preferably, the cationic part of the quaternary ammonium salt type cationic surfactant is one or both combinations of the structural formulas shown in the following figure:

[0046]

[0047] In the polishing composition, the surfactant improves the dispersibility of the silica particles, prevents particle aggregation, and thereby improves the stability and polishing effect of the polishing composition by reducing the interfacial tension between the liquid and the particles. In addition, it can reduce the EOE phenomenon caused by the too fast tungsten corrosion rate. The surfactant can adsorb on the tungsten surface to form a protective layer, isolate the corrosive components, and at the same time neutralize the surface charge, reduce the electrochemical activity. In addition, it can also reduce the surface tension of the polishing composition, improve the dispersibility of the abrasive, make the polishing more uniform, and at the same time interact with the corrosive components, inhibit the chemical reaction, increase the corrosion activation energy, slow down the corrosion rate, and finally reduce the impact and wear on the tungsten surface by adjusting the rheological properties of the polishing composition, thereby effectively reducing the EOE phenomenon caused by the too fast tungsten corrosion rate.

[0048] <Chemical Mechanical Polishing Composition for Tungsten>

[0049] The present invention provides a chemical mechanical polishing composition for tungsten. The chemical mechanical polishing composition for tungsten, in addition to including the above surfactant, further includes abrasive particles, a catalyst, a chelating agent, a corrosion inhibitor, a bactericide, and an oxidizing agent.

[0050] pH of the polishing composition

[0051] In the present invention, the pH of the chemical mechanical polishing composition for tungsten is 2 to 7, and preferably the pH of the chemical mechanical polishing composition for tungsten is 3 to 5. An acidic environment (pH < 7) is beneficial to improving the polishing efficiency because, under acidic conditions, the oxidant (such as hydrogen peroxide) has higher activity and can react more effectively with the tungsten surface to form an oxide layer that is easily mechanically removed. Secondly, the pH value has an important influence on the stability and dispersibility of the polishing composition. Too low or too high a pH value may cause precipitation or agglomeration of the components (such as abrasive particles) in the polishing composition, affecting the polishing effect. In addition, the pH value also affects the corrosiveness of the polishing composition. Too low a pH value may increase the corrosion of the polishing equipment, while a higher pH value may reduce the selectivity of the polishing composition. Therefore, controlling the pH value within the range of 2 to 7 can take into account the stability of the polishing composition and the corrosion resistance of the equipment while ensuring the polishing efficiency.

[0052] Chelating agent

[0053] In the present invention, the chelating agent includes one or more combinations of malonic acid, citric acid, and maleic acid. Preferably, the chelating agent includes one or both combinations of malonic acid and citric acid. More preferably, the chelating agent is malonic acid. In the polishing composition, chelating agents such as malonic acid, citric acid, and maleic acid can form stable chelates with metal ions such as iron ions and tungsten ions, thereby preventing these metal ions from precipitating or reacting with other components, maintaining their solubility and activity in the polishing composition, and at the same time regulating their catalytic activity by chelating iron ions, controlling the decomposition rate of hydrogen peroxide, avoiding the EOE phenomenon caused by too fast a corrosion reaction. In addition, it can also chelate tungsten ions to prevent them from redepositing on the workpiece surface during the polishing process, avoiding secondary pollution and surface defects, and further improving the chemical stability and service life of the polishing composition.

[0054] In the present invention, the chelating agent is combined with the above surfactants. The chelating agent forms a protective layer by complexing metal ions and reducing metal corrosion, while the surfactant adjusts the surface tension, enhances the wettability, and stabilizes the solution. The combination of the two can effectively inhibit the excessive corrosion of tungsten, reduce corrosion non-uniformity, and further reduce the EOE phenomenon caused by too fast a tungsten corrosion rate. The above six surfactants, namely dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, cetyltrimethylammonium chloride, cetyl dimethylbenzyl ammonium chloride, N,N'-bis(dodecyldimethyl)-1,4-phenylenedimethylammonium chloride, N,N'-bis(tetradecyldimethyl)-1,4-phenylenedimethylammonium chloride, and the above three chelating agents, namely malonic acid, citric acid, and maleic acid, can be arbitrarily combined. Preferably, the combination is N,N'-bis(tetradecyldimethyl)-1,4-phenylenedimethylammonium chloride and malonic acid.

[0055] Abrasive particles

[0056] In the present invention, the abrasive particles include one or a combination of silica, cerium oxide, and alumina.

[0057] Silica (SiO2), cerium oxide (CeO2), and alumina (Al2O3) are common abrasive particles and are widely used in polishing compositions. The reason they can be used as abrasive particles in polishing compositions is mainly because they have strong hardness, high chemical stability, and good dispersibility.

[0058] As a common abrasive particle, silica is widely used because of its moderate hardness. It can effectively remove the uneven materials on the surface and will not cause excessive scratches to the substrate during the polishing process. Silica is very stable chemically and is not easy to react with the material to be polished. Therefore, it can maintain high grinding performance and reduce damage to the workpiece. In addition, the particles of silica are usually relatively uniform, which helps to improve the smoothness and consistency of the polishing process.

[0059] Cerium oxide has very high hardness and chemical stability and is particularly suitable for polishing hard materials. Compared with silica, it is suitable for removing larger defects on the material surface, but it may cause certain scratches to softer materials.

[0060] Alumina is one of the commonly used abrasive particles with high hardness, and its hardness is higher than that of cerium oxide. Its main advantage lies in its very strong grinding ability and is suitable for rough machining of materials with higher hardness. Since alumina particles are hard and sharp, they can quickly remove the material layer, but the particle shape and properties of alumina may also cause more surface scratches.

[0061] Silica is lower than alumina and cerium oxide in particle size and hardness and has better surface treatment effect. Its relatively gentle grinding characteristics make it particularly suitable for fine polishing to avoid excessive wear and scratches. In contrast, although alumina and cerium oxide have higher hardness and are suitable for rough machining, they may cause damage to finer surfaces. Therefore, silica is a very ideal abrasive particle in precision polishing. Especially in applications that require higher surface smoothness and lower surface damage, silica has obvious advantages.

[0062] In the present invention, the average particle size of silica is 40 - 80 nm. When the particle size is less than 40 nm, since the smaller particles remove less material per unit time, it may significantly reduce the material removal rate; while when the particle size is greater than 80 nm, it may cause greater wear and surface scratches, affecting the overall polishing effect. Setting the particle size of silica within the above range can provide better polishing effect.

[0063] The above-mentioned abrasive particles include, but are not limited to, a series of abrasive particles produced by Fusang Company: any one or a combination of more than one of PL-1, PL-2, PL-3, PL-5, and PL-6.

[0064] In the present invention, the Zeta potential of silica is 15 to 55 mV. Setting the Zeta potential of silica within the above range helps to maintain the stable dispersion of particles and good polishing effect. If the Zeta potential is lower than this range, the mutual attraction between silica particles increases, which may lead to particle aggregation or agglomeration. This aggregation phenomenon will lead to a decrease in the stability of the polishing composition, and the polishing particles cannot be evenly distributed in the liquid, thus affecting the uniformity of the polishing process and resulting in uneven surface wear or poor effect. On the contrary, when the Zeta potential is higher than 55 mV, the repulsive force between silica particles is too strong, reducing the contact probability between silica and the polishing surface, resulting in a decrease in the material removal rate (MRR).

[0065] The positively charged abrasive particles can be obtained by any suitable method that can provide positive charges to the abrasive particles. Generally, the surface of the abrasive particles is covered by a grafting method to make them carry positive charges. The specific method is as follows: adjust the pH of the abrasive particles to 9.0 with ammonia water, heat to 40 °C, dropwise add aminopropyltrimethoxysilane, keep warm for 1 h, then distill at normal pressure with a constant liquid level until the top temperature of the tower reaches 100 °C and end, and filter to obtain the positively charged abrasive particles.

[0066] By controlling the ratio of the mass of aminopropyltrimethoxysilane to the mass of the abrasive particles within the range of 0.2% to 1.8%, abrasive particles with a Zeta potential of 10 to 65 mV can be obtained. It can be cited that when the ratio of the mass of aminopropyltrimethoxysilane to the mass of the abrasive particles is 0.2%, the Zeta potential of the abrasive particles is 10 mV; when the ratio is 0.3%, the Zeta potential of the abrasive particles is 15 mV; when the ratio is 0.5%, the Zeta potential of the abrasive particles is 20 mV; when the ratio is 0.8%, the Zeta potential of the abrasive particles is 35 mV; when the ratio is 1.0%, the Zeta potential of the abrasive particles is 40 mV; when the ratio is 1.2%, the Zeta potential of the abrasive particles is 50 mV; when the ratio is 1.3%, the Zeta potential of the abrasive particles is 55 mV; when the ratio is 1.8%, the Zeta potential of the abrasive particles is 65 mV.

[0067] Catalyst

[0068] In the present invention, the catalyst includes one or a combination of ferric nitrate, ferric sulfate, ferric chloride, and ferric bromide. In the presence of an oxidant (such as hydrogen peroxide), these iron salt catalysts can catalyze the formation of highly oxidizing active substances (such as hydroxyl radicals ·OH), which can react with the tungsten surface to form an oxide layer that is easily removed mechanically, thereby significantly improving the polishing rate and removal efficiency of tungsten.

[0069] In the present invention, preferably, the catalyst is ferric nitrate. Compared with ferric sulfate, ferric nitrate has higher catalytic activity and can more effectively catalyze the decomposition of hydrogen peroxide to generate hydroxyl radicals, thus improving the polishing rate of tungsten. Ferric nitrate has good stability in aqueous solution and is not prone to hydrolysis reactions, which helps to maintain the chemical stability of the polishing composition. In contrast, ferric chloride and ferric bromide are easily hydrolyzed in aqueous solution to form ferric hydroxide and the corresponding acids, which may affect the pH value and stability of the polishing composition.

[0070] Corrosion inhibitor

[0071] In the present invention, the corrosion inhibitor includes one or a combination of lysine, arginine, and proline, preferably includes one or a combination of lysine and arginine, and more preferably, the corrosion inhibitor is lysine. The functional groups (such as amino groups and carboxyl groups) in the corrosion inhibitor can chemically adsorb on the tungsten surface to form a stable protective film, preventing the corrosive components (such as ferric nitrate and hydrogen peroxide) in the polishing composition from directly contacting the tungsten surface, thereby reducing the occurrence of corrosion reactions.

[0072] Bactericide

[0073] In the present invention, the bactericide includes one or a combination of methylisothiazolinone, 5-chloro-2-methyl-4-isothiazolin-3-one, and 1,2-benzisothiazolin-3-one, preferably 5-chloro-2-methyl-4-isothiazolin-3-one. In the polishing composition, bactericides such as MIT (methylisothiazolinone), CMIT (5-chloro-2-methyl-4-isothiazolin-3-one), and BIT (1,2-benzisothiazolin-3-one) can effectively prevent the growth of microorganisms such as bacteria, molds, and yeasts in the polishing composition. These bactericides have the characteristics of broad-spectrum, high-efficiency, and low toxicity, which can ensure the stability of the polishing composition during storage and use, and avoid performance degradation and quality problems caused by microbial contamination.

[0074] Oxidizing agent

[0075] In the present invention, the oxidizing agent includes one or a combination of hydrogen peroxide, persulfate, and periodate. Preferably, the oxidizing agent is hydrogen peroxide. In the polishing composition, the main function of the oxidizing agent is to chemically react with the surface of the material to be polished, forming a soft substance that is easily removed mechanically, thereby achieving efficient and uniform material removal. The advantage of hydrogen peroxide compared to other oxidizing agents is that its decomposition products are water and oxygen, which are environmentally friendly, and it has strong oxidizing ability, capable of effectively oxidizing the tungsten surface to form an oxide layer that is easily removed mechanically. In addition, hydrogen peroxide has good compatibility with other components (such as catalysts) in the polishing composition and can act synergistically to improve the polishing efficiency.

[0076] Proportion of each substance

[0077] In the present invention, the chemical mechanical polishing composition for tungsten comprises 0.5 - 5.0 wt% of abrasive particles, a catalyst, a chelating agent, a corrosion inhibitor, 0.01 - 0.2 wt% of the surfactant as described above, a bactericide, and an oxidizing agent; preferably, the chemical mechanical polishing composition for tungsten comprises 1.0 - 3.0 wt% of abrasive particles, a catalyst, a chelating agent, a corrosion inhibitor, 0.05 - 0.1 wt% of the surfactant as described above, a bactericide, and an oxidizing agent.

[0078] Setting the contents of each component within the above ranges can ensure that while providing sufficient mechanical grinding force, the risk of scratches and other surface damages caused by excessive concentration of abrasive particles is avoided; 0.01 - 0.2 wt% of the surfactant is sufficient to ensure good dispersibility and stability of the polishing composition, while avoiding affecting other properties of the polishing composition due to excessive concentration.

[0079] <Method for polishing a substrate>

[0080] In the present invention, the chemical mechanical polishing composition for tungsten can be applied to tungsten chemical mechanical polishing.

[0081] During the polishing process, the polishing composition is continuously dropped onto the polishing pad, and the substrate containing tungsten is tightly pressed onto the polishing pad rotating at high speed. The oxidizing agent in the polishing composition chemically reacts with the surface of the substrate to form an oxide layer. At the same time, the chelating agent combines with the reaction product and dissolves it in the polishing composition to prevent it from accumulating on the surface of the substrate. The abrasive particles in the polishing composition mechanically grind the surface of the substrate under the action of pressure and rotation, removing the oxide layer generated by the chemical reaction and exposing a new surface. The new surface is chemically oxidized again, and so on, ultimately achieving the planarization of the surface of the substrate. As the polishing progresses, it is necessary to regularly supplement fresh polishing composition to maintain the concentration and performance of the polishing composition.

[0082] The above and other advantages of the present invention can be better understood through the following embodiments, but the following embodiments are not intended to limit the scope of the present invention.

[0083] Example

[0084] The following gives examples to illustrate the present invention, but the present invention is not limited by the following examples.

[0085] Synthesis Example 1

[0086] Dodecyl chloride and trimethylamine were placed in a reaction kettle at a molar ratio of 1.1:1, water was added as a solvent, and the mixture was stirred and reacted at 70 °C for 4 h. After the reaction was stopped, the reaction solution was cooled to 4 °C. The precipitated crystals were filtered and then recrystallized with ethanol. After drying, white powdered solid A1 of dodecyltrimethylammonium chloride was obtained.

[0087] Synthesis Example 2

[0088] N,N-Dimethyl-dodecyl tertiary amine and benzyl chloride were placed in a reaction kettle at a molar ratio of 1.1:1, water was added as a solvent, and the mixture was stirred and reacted at 90 °C for 5 h. After the reaction was stopped, the reaction solution was cooled to 4 °C. The precipitated crystals were filtered and then recrystallized with ethanol. After drying, white powdered solid A2 of dodecyldimethylbenzylammonium chloride was obtained.

[0089] Synthesis Example 3

[0090] Hexadecyl chloride and trimethylamine were placed in a reaction kettle at a molar ratio of 1.1:1, water was added as a solvent, and the mixture was stirred and reacted at 70 °C for 4 h. After the reaction was stopped, the reaction solution was cooled to 4 °C. The precipitated crystals were filtered and then recrystallized with ethanol. After drying, white powdered solid A3 of hexadecyltrimethylammonium chloride was obtained.

[0091] Synthesis Example 4

[0092] N,N-Dimethyl-hexadecyl tertiary amine and benzyl chloride were placed in a reaction kettle at a molar ratio of 1.1:1, water was added as a solvent, and the mixture was stirred and reacted at 90 °C for 5 h. After the reaction was stopped, the reaction solution was cooled to 4 °C. The precipitated crystals were filtered and then recrystallized with ethanol. After drying, white powdered solid A4 of hexadecyldimethylbenzylammonium chloride was obtained.

[0093] Synthesis Example 5

[0094] N,N-Dimethyl-dodecyl tertiary amine and p-dichlorobenzene (XDC) were placed in a reaction kettle at a molar ratio of 2.2:1, anhydrous ethanol was added as a solvent, and the mixture was stirred and reacted at 75 °C for 4 h. After the reaction was stopped, the reaction solution was cooled to 4 °C. The precipitated crystals were filtered and then recrystallized with ethanol. After drying, white powdered solid A5 of N,N'-bis(dodecyldimethyl)-1,4-phenylenedimethylammonium chloride was obtained.

[0095] Synthesis Example 6

[0096] N,N-Dimethyl-tetradecyl tertiary amine and p-dichlorobenzyl (XDC) were placed in a reaction kettle at a molar ratio of 2.2:1, anhydrous ethanol was added as a solvent, and the mixture was stirred and reacted at 75 °C for 4 h. After the reaction was stopped, the reaction solution was cooled to 4 °C. The precipitated crystals were filtered and then recrystallized with ethanol. After drying, white powdery solid A6 of N,N'-bis(tetradecyldimethyl)-1,4-phenylenedimethylammonium chloride was obtained.

[0097] Table 1 shows the components and contents of the tungsten polishing composition in the examples and comparative examples of the present invention. A chemical mechanical polishing composition was prepared by simply stirring and mixing 0.15 wt% of ferric nitrate catalyst, 0.0015 wt% of 5-chloro-2-methyl-4-isothiazolin-3-one fungicide, 0.25 wt% of chelating agent, 0.035 wt% of corrosion inhibitor and the formulation shown in Table 1. After mixing evenly, the pH value was adjusted with potassium hydroxide or nitric acid. 1.5 wt% of hydrogen peroxide was added before use and mixed evenly, and the balance was made up to 100 wt% with water to obtain the polishing compositions of the examples and comparative examples of the present invention.

[0098] Table 1

[0099]

[0100] To verify the polishing effect of the polishing composition of the present invention, the polishing compositions in the examples and comparative examples were used to polish Tungsten / OX blank and Tungsten 754 wafers respectively. The polishing conditions were as follows: LK (CMP machine), DH3010H (purchased from DINGLONG Co., Ltd) polishing pad, pressure of 2.0 psi, polishing base / polishing head rotation speed of 93 / 87 rpm, polishing composition flow rate of 300 mL / min, and the evaluation results are shown in Table 2:

[0101] Table 2

[0102]

[0103] It should be noted that according to the explanations and elaborations in the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some equivalent modifications and changes to the present invention should also be within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the invention.

Claims

1. A surfactant, characterized in that, The surfactant is a quaternary ammonium salt type cationic surfactant, and the structural formula of its cationic part is Among them, R1 to R 11 each independently includes one or more combinations of methyl, an alkyl group having 12 to 16 carbon atoms, p-phenylenedimethylene, alkenyl, benzyl, hydroxyl group, heterocyclic group, carboxyl group, and amino group.

2. The surfactant according to claim 1, characterized in that, The cationic part of the quaternary ammonium salt type cationic surfactant is one or a combination of more than one of the structural formulas shown in the following figure:

3. The surfactant according to claim 2, characterized in that, The cationic part of the quaternary ammonium salt type cationic surfactant is one or a combination of two of the structural formulas shown in the following figure:

4. A chemical mechanical polishing composition for tungsten, characterized in that, The chemical mechanical polishing composition for tungsten includes 0.5 - 5.0 wt% of abrasive particles, a catalyst, a chelating agent, a corrosion inhibitor, 0.01 - 0.2 wt% of the surfactant as described in any one of claims 1 - 3, a bactericide, and an oxidizing agent; The pH of the chemical mechanical polishing composition for tungsten is 2 - 7.

5. The chemical mechanical polishing composition for tungsten according to claim 4, wherein The chemical mechanical polishing composition for tungsten includes 1.0 - 3.0 wt% of abrasive particles, a catalyst, a chelating agent, a corrosion inhibitor, 0.05 - 0.1 wt% of the surfactant as described in any one of claims 1 - 3, a bactericide, and an oxidizing agent; The pH of the chemical mechanical polishing composition for tungsten is 3 - 5.

6. The chemical mechanical polishing composition for tungsten according to claim 4 or 5, characterized in that, The chelating agent includes one or a combination of more than one of malonic acid, citric acid, and maleic acid. Preferably, the chelating agent is malonic acid.

7. The chemical mechanical polishing composition for tungsten according to claim 4 or 5, characterized in that, The abrasive particles include one or a combination of more than one of silica, cerium oxide, and alumina.

8. The chemical mechanical polishing composition for tungsten according to claim 7, wherein The abrasive particles are silica, the average particle size of the silica is 40 - 80 nm, and the Zeta potential of the silica is 15 - 55 mV.

9. The chemical mechanical polishing composition for tungsten according to claim 4 or 5, characterized in that, The catalyst includes one or a combination of more than one of iron nitrate, iron sulfate, iron chloride, and iron bromide. Preferably, the catalyst is iron nitrate; The corrosion inhibitor includes one or a combination of more than one of lysine, arginine, and proline. Preferably, the corrosion inhibitor includes one or a combination of two of lysine and arginine; The bactericide includes one or a combination of more than one of methylisothiazolinone, 5 - chloro - 2 - methyl - 4 - isothiazolin - 3 - one, and 1,2 - benzisothiazolin - 3 - one. Preferably, the bactericide is 5 - chloro - 2 - methyl - 4 - isothiazolin - 3 - one; The oxidizing agent includes one or a combination of more than one of hydrogen peroxide, persulfate, and periodate. Preferably, the oxidizing agent is hydrogen peroxide.

10. A method for polishing a substrate, characterized in that, Comprising: (i) Providing a substrate containing tungsten; (ii) Providing a polishing pad; (iii) Providing the chemical mechanical polishing composition as described in claim 4; (iv) Bringing the substrate into contact with the polishing pad and the chemical mechanical polishing composition; and (v) Moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to grind at least a part of the substrate to polish the substrate.

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