Chemical mechanical polishing composition for polishing monocrystalline silicon substrate and polishing method

Abstract

The invention provides a chemical mechanical polishing composition for polishing a monocrystalline silicon substrate and a polishing method. The composition comprises the following components: first silicon oxide abrasive particles which comprise colloidal silicon dioxide abrasive particles, are spherical and have an average particle size of 10-150 nm; the second silicon dioxide abrasive particles comprise gas-phase silicon dioxide abrasive particles, are in irregular shapes and have the average particle size of 50-300 nm; and the polishing additive is matched with the first silicon oxide abrasive particles and the second silicon oxide abrasive particles, so that the polishing quality and the material removal rate of the monocrystalline silicon substrate are improved.

Description

Technical Field

[0001] This application relates to the field of chemical mechanical polishing technology, and more particularly to a chemical mechanical polishing composition and polishing method for polishing single-crystal silicon substrates. Background Technology

[0002] In the processing of single-crystal silicon substrates, chemical mechanical polishing (CMP) is a key process for achieving atomically smooth surfaces and is widely used in wafer planarization in semiconductor manufacturing. Currently, colloidal silica abrasives are commonly used in industry as the abrasive media in CMP compositions. However, silica abrasives primarily operate through rolling and sliding friction, resulting in a relatively low coefficient of friction, weak cutting action, and limited material removal rates, making it difficult to meet the high production efficiency requirements of advanced processes.

[0003] Furthermore, because colloidal silica abrasive particles are susceptible to hydrodynamic behavior in chemical mechanical polishing compositions, it is difficult to form a stable and uniform contact pressure distribution on the surface of single-crystal silicon wafers, easily leading to uneven material removal in certain areas. This non-uniform removal behavior not only limits the improvement of removal efficiency but also leads to increased surface micro-undulations, scratches, and roughness, affecting the surface flatness and quality consistency of the final wafer.

[0004] Therefore, how to effectively control surface roughness while improving material removal rate, and achieve synergistic optimization of high efficiency and high precision, has become the core challenge facing the single-crystal silicon CMP process. Summary of the Invention

[0005] This application provides a chemical mechanical polishing composition and method for polishing single-crystal silicon substrates. In this composition, a mixture of colloidal silica abrasives and fumed silica abrasives is used as polishing abrasives, which effectively controls surface roughness while improving material removal rate.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, embodiments of this application provide a chemical mechanical polishing composition for polishing a single-crystal silicon substrate, comprising: a first silicon oxide abrasive, including colloidal silicon dioxide abrasive, and being spherical with an average particle size of 10-150 nm; a second silicon oxide abrasive, including fumed silicon dioxide abrasive, and being irregularly shaped with an average particle size of 50-300 nm; and a polishing aid, which works in conjunction with the first silicon oxide abrasive and the second silicon oxide abrasive to improve the polishing quality and material removal rate of the single-crystal silicon substrate.

[0008] According to some embodiments of this application, the mass ratio of the first silicon oxide abrasive grains to the second silicon oxide abrasive grains ranges from 3:7 to 9:1, wherein the proportion of the first silicon oxide abrasive grains to the mass ratio of the abrasive grains is between 30% and 90%, and the proportion of the second silicon oxide abrasive grains to the mass ratio of the abrasive grains is between 10% and 70%.

[0009] According to some embodiments of this application, the mass ratio of the first silicon oxide abrasive grains to the second silicon oxide abrasive grains ranges from 4:6 to 8:2, wherein the proportion of the first silicon oxide abrasive grains to the mass ratio of the abrasive grains is between 40% and 80%, and the proportion of the second silicon oxide abrasive grains to the mass ratio of the abrasive grains is between 20% and 60%.

[0010] According to some embodiments of this application, the polishing aid includes a surfactant, which includes at least one of a nonionic surfactant or a cationic surfactant.

[0011] According to some embodiments of this application, the nonionic surfactant includes alkylphenol polyoxyethylene ether.

[0012] According to some embodiments of this application, the number of carbon atoms m of the alkyl group in the alkylphenol polyoxyethylene ether ranges from 2 to 20, and the degree of polymerization n ranges from 5 to 200. The alkylphenol polyoxyethylene ether can be any combination of the number of atoms and the degree of polymerization.

[0013] According to some embodiments of this application, the alkylphenol polyoxyethylene ether includes at least one of octylphenol polyoxyethylene ether, heptaphenol polyoxyethylene ether, hexylphenol polyoxyethylene ether, decylphenol polyoxyethylene ether, and nonylphenol polyoxyethylene ether.

[0014] According to some embodiments of this application, the alkylphenol polyoxyethylene ether includes nonylphenol polyoxyethylene ether.

[0015] According to some embodiments of this application, the cationic surfactant includes 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-ammonium halide.

[0016] According to some embodiments of this application, the 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-ammonium halide comprises 2,3-bis(dodecyloxy)-N-(2-hydroxyethyl)-N,N-dimethylpropane-1-bromide.

[0017] In a second aspect, embodiments of this application provide a polishing method for a single-crystal silicon substrate, the method utilizing a composition as described in any one of the first aspects above to polish the single-crystal silicon substrate. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A scanning electron microscope image of colloidal silica abrasive grains with an average particle size of 70 nm, measured by dynamic light scattering, is shown according to an embodiment of this application.

[0020] Figure 2 A scanning electron microscope image of fumed silica abrasive grains with an average particle size of 155 nm, measured by dynamic light scattering, is shown according to an embodiment of this application. Detailed Implementation

[0021] The following description provides specific application scenarios and requirements for this specification, intended to enable those skilled in the art to make and use the contents of this specification. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0022] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not restrictive. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” used herein may also include the plural forms. When used in this specification, the terms “comprising,” “including,” and / or “containing” mean that the associated integers, steps, operations, elements, and / or components are present, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups, or that other features, integers, steps, operations, elements, components, and / or groups may be added to the system / method.

[0023] In this application, "X includes at least one of A, B, or C" means that X includes at least A, or X includes at least B, or X includes at least C. That is, X can include any combination of A, B, and C, or any combination of A, B, and C, as well as other possible content / elements. The arbitrary combination of A, B, and C can be A, B, C, AB, AC, BC, or ABC.

[0024] Monocrystalline silicon, as a key semiconductor material, is widely used in integrated circuits (ICs), microelectromechanical systems (MEMS), solar cells, power devices, and various sensors due to its excellent electrical properties, high carrier mobility, and highly ordered crystal structure. For example, in modern high-performance computing chips such as CPUs, monocrystalline silicon is the basic substrate material for building transistor arrays; in high-efficiency photovoltaic modules, high-purity monocrystalline silicon can achieve excellent photoelectric conversion efficiency. To meet the stringent requirements of these advanced applications for device performance and reliability, monocrystalline silicon wafers must possess extremely high surface flatness, extremely low surface roughness (typically reaching sub-nanometer levels), and a virtually defect-free clean surface during manufacturing. Therefore, chemical mechanical polishing (CMP) has become an indispensable core process in wafer fabrication, used to achieve global planarization and atomic-level surface smoothness.

[0025] Currently, colloidal silica abrasives are widely used in industry as the polishing medium in chemical mechanical polishing compositions for single-crystal silicon substrates. Colloidal silica particles have a highly monodisperse spherical structure, narrow particle size distribution, and smooth surface. During polishing, they form a uniform and gentle contact with the silicon wafer surface, effectively reducing scratches and localized stress concentrations. Simultaneously, the excellent dispersion stability of colloidal silica avoids surface defects caused by agglomeration, thus facilitating the achievement of ultra-smooth surfaces. However, precisely because of its dense particles, relatively low hardness, and predominantly rolling and sliding motion, its mechanical polishing ability is weak, and material removal mainly relies on chemical action, resulting in a relatively low removal rate.

[0026] To improve material removal rate while controlling surface roughness, this application provides a chemical mechanical polishing composition and polishing method for polishing single-crystal silicon substrates. In this composition, a mixture of colloidal silica abrasives and fumed silica abrasives is used as the polishing abrasives. While fumed silica can achieve high material removal rates on single-crystal silicon substrates, its chain-like secondary structure formed by the aggregation of native nanoparticles may break or plow during polishing, making it more prone to surface scratches and defects. Colloidal silica, due to its uniform particle size and good dispersion, typically achieves better surface quality, but its removal rate is lower. Combining the two fully leverages the high removal efficiency of fumed silica and the fine finishing advantages of colloidal silica, significantly improving the polishing rate while maintaining good surface integrity, achieving synergistic optimization of removal rate and surface quality.

[0027] Before describing the specific embodiments in this specification, the application scenarios of this specification will be introduced as follows. The chemical mechanical polishing composition will be referred to simply as the composition.

[0028] The composition provided in this specification can be used for polishing single-crystal silicon substrates and is suitable for chemical mechanical polishing (CMP) processes in multiple key stages of semiconductor manufacturing. Specifically, it can be applied to the final polishing stage of single-crystal silicon wafers to remove residual micro-surface damage, hazy defects, and nanoscale roughness after previous processes (such as grinding, rough polishing, or epitaxial growth), achieving an atomically smooth, scratch-free, and residue-free clean surface. Simultaneously, this composition can also be used in the initial stock polishing stage to improve material removal rates. It is particularly suitable for advanced process applications with extremely high surface quality requirements, such as polishing high-purity single-crystal silicon substrates used in logic chips (CPUs), memory (DRAM, 3D NAND), and power devices. It can also be used for efficient surface treatment of single-crystal silicon wafers for solar cells, effectively suppressing particle adhesion and surface defect generation while maintaining high material removal rates, meeting the demands of high-yield and high-cleanliness industrial production.

[0029] The composition includes abrasive grains. These abrasive grains help remove excess material from the surface of a monocrystalline silicon substrate during polishing. Among the various abrasive grains, silicon oxide abrasive grains have moderate hardness, thus effectively improving material removal efficiency while avoiding scratches on the surface of the monocrystalline silicon substrate, thereby reducing surface depressions and resulting in a high degree of surface flatness.

[0030] The silica abrasive particles in this composition constitute 2 wt% to 30 wt% of the composition by weight. In some embodiments, the silica abrasive particles in this composition constitute 5 wt% to 20 wt% of the composition by weight. In some embodiments, the silica abrasive particles in this composition constitute 5 wt% to 10 wt% of the composition by weight. Further, the silica abrasive particles in this composition can be selected as being between 2 wt% to 5 wt%, 5 wt% to 10 wt%, 10 wt% to 15 wt%, 15 wt% to 20 wt%, 20 wt% to 25 wt%, or 25 wt% to 30 wt%. It is understood that the above ranges of silica abrasive particle weight percentages can be arbitrarily combined; for example, the silica abrasive particles in this composition may be in the range of 5 wt% to 15 wt%.

[0031] The silica abrasive particles in the composition have a zeta potential of -5 mV to -60 mV at pH values ​​of 11-12. In some embodiments, the silica abrasive particles in the composition have a zeta potential of -17 mV to -30 mV at pH values ​​of 11-12. Furthermore, the silica abrasive particles in the composition have zeta potentials of -5mV to -7mV, -7mV to -10mV, -10mV to -15mV, -15mV to -17mV, -17mV to -20mV, -20mV to -25mV, -25mV to -27mV, -27mV to -30mV, -30mV to -35mV, -35mV to -37mV, -37mV to -40mV, -40mV to -45mV, -45mV to -47mV, -47mV to -50mV, -50mV to -55mV, -55mV to -57mV, and -57mV to -60mV at pH values ​​of composition 11-12. It is understood that the zeta potential of the silica abrasive particles in the composition at pH values ​​of 11-12 can be arbitrarily combined. For example, the silica abrasive particles in the composition at pH values ​​of 11-12 have a potential of -5mV to -17mV.

[0032] The silica abrasives in this solution include first silica abrasives and second silica abrasives. The first silica abrasives are colloidal silica abrasives. Colloidal silica abrasives, due to their uniform particle size, good dispersibility, and smooth surface, allow for more precise control during polishing, effectively reducing surface scratches and defects, and achieving excellent surface quality. The second silica abrasives are fumed silica abrasives. Fumed silica abrasives have high reactivity and a large specific surface area, providing strong chemical action and a high material removal rate, which is beneficial for improving polishing efficiency. Combining colloidal silica abrasives and fumed silica abrasives leverages both the high removal rate of fumed silica abrasives and the surface smoothness-improving ability of colloidal silica abrasives, thus achieving an overall higher material removal rate and better surface quality.

[0033] In some embodiments, the mass ratio of first silica abrasive particles to second silica abrasive particles in the total abrasive particles ranges from 3:7 to 9:1, meaning the mass ratio of first silica abrasive particles to the total abrasive particles is between 30% and 90%, and the mass ratio of second silica abrasive particles to the total abrasive particles is between 10% and 70%. For example, the mass ratio of first silica abrasive particles to second silica abrasive particles in the total abrasive particles is between 3:7 and 1:1, meaning the mass ratio of first silica abrasive particles to the total abrasive particles is between 30% and 50%, and the mass ratio of second silica abrasive particles to the total abrasive particles is between 50% and 70%. At this ratio, the content of fumed silica abrasive particles (second silica abrasive particles) is relatively high, which can fully utilize their high reactivity and large specific surface area, making them particularly suitable for processes with extremely high polishing efficiency. For example, the mass ratio of first silica abrasive particles to second silica abrasive particles in the total abrasive particles is 1:1, meaning the mass ratio of first silica abrasive particles to the total abrasive particles is 50%, and the mass ratio of second silica abrasive particles to the total abrasive particles is 50%. In this scenario, the ratio of fumed silica abrasive particles to colloidal silica abrasive particles is equal, making it suitable for applications requiring both high material removal rates and high surface quality. For example, the mass ratio of primary silica abrasive particles to secondary silica abrasive particles in the total abrasive particles is 1:1 to 9:1, meaning the primary silica abrasive particles account for 50% to 90% of the total abrasive particles, while the secondary silica abrasive particles account for 10% to 50%. At this ratio, the content of colloidal silica abrasive particles (primary silica abrasive particles) is relatively high, allowing for more precise control during polishing and effectively reducing surface scratches and defects. This makes it particularly suitable for applications with extremely high surface quality requirements.

[0034] In some embodiments, the mass ratio of the first silicon oxide abrasive grains to the second silicon oxide abrasive grains in the total abrasive grains ranges from 4:6 to 8:2, that is, the mass ratio of the first silicon oxide abrasive grains to the total abrasive grains is between 40% and 80%, and the mass ratio of the second silicon oxide abrasive grains to the total abrasive grains is between 20% and 60%. For example, the mass ratio of the first silicon oxide abrasive grains to the second silicon oxide abrasive grains in the total abrasive grains is from 4:6 to 1:1, that is, the mass ratio of the first silicon oxide abrasive grains to the total abrasive grains is 40%-50%, and the mass ratio of the second silicon oxide abrasive grains to the total abrasive grains is 50%-60%. For example, the mass ratio of the first silicon oxide abrasive grains to the second silicon oxide abrasive grains in the total abrasive grains is from 1:1 to 8:2, that is, the mass ratio of the first silicon oxide abrasive grains to the total abrasive grains is 50%-80%, and the mass ratio of the second silicon oxide abrasive grains to the total abrasive grains is 20%-50%.

[0035] Among them, the first silica abrasive grains are abrasive particles with a spherical morphology, that is, colloidal silica abrasive grains are abrasive particles with a spherical morphology. Figure 1 A scanning electron microscope image of colloidal silica abrasive grains with an average particle size of 70 nm, provided according to an embodiment of this application, is shown. Figure 1 As shown, the term "spherical" is not limited to a geometrically perfect sphere, but rather refers to a particle morphology with a rounded overall outline and no obvious sharp edges or vertices, including near-spherical structures with low elongation such as grape-like aggregates, ellipsoids, ovoids, cocoons, or potato-shaped particles. These particles have smooth surfaces without numerous rough, sharp, or serrated protrusions, significantly reducing the risk of surface defects such as scratches and pits caused by localized stress concentration during polishing. This morphological characteristic can be observed and determined by those skilled in the art using conventional characterization methods such as transmission electron microscopy (TEM) or scanning electron microscopy (SEM). Spherical colloidal silica, due to its excellent dispersion stability, uniform particle size distribution, and mild mechanical action, contributes to achieving more uniform material removal and higher surface finish. Currently, high-quality spherical colloidal silica is commercially available from specialized suppliers such as AkzoNobel (Amsterdam, Netherlands), Nissan Chemical (Houston, Texas, USA), Fuso Chemical, and Nalco.

[0036] In some embodiments, the average particle size range of the dispersed first silica abrasive particles in the composition can be 10 nm-150 nm. In some embodiments, the average particle size range of the dispersed first silica abrasive particles in the composition can be 20 nm-120 nm. In some embodiments, the average particle size range of the dispersed first silica abrasive particles in the composition can be 30 nm-100 nm. Further, the average particle size range of the first silica abrasive particles can be 10 nm-20 nm, 20 nm-30 nm, 30 nm-40 nm, 40 nm-50 nm, 50 nm-60 nm, 60 nm-70 nm, 70 nm-80 nm, 80 nm-90 nm, 90 nm-100 nm, 100 nm-110 nm, 110 nm-120 nm, 120 nm-130 nm, 130 nm-140 nm, or 140 nm-150 nm. Furthermore, the average particle size range of the first silica abrasive grains can be a combined range of any of the above ranges, such as 10nm-60nm, 80nm-120nm, etc. It is understood that the average particle size of the first silica abrasive grains can be measured by dynamic light scattering measurement (e.g., using a Malvern Mastersizer S from Malvern Instruments).

[0037] The first silica abrasive grains in the composition have a zeta potential of -5 mV to -60 mV at a pH of 11-12. In some embodiments, the first silica abrasive grains in the composition have a zeta potential of -15 mV to -40 mV at a pH of 11-12. Furthermore, the first silica abrasive particles in the composition have zeta potentials of -5mV to -7mV, -7mV to -10mV, -10mV to -15mV, -15mV to -17mV, -17mV to -20mV, -20mV to -25mV, -25mV to -27mV, -27mV to -30mV, -30mV to -35mV, -35mV to -37mV, -37mV to -40mV, -40mV to -45mV, -45mV to -47mV, -47mV to -50mV, -50mV to -55mV, -55mV to -57mV, and -57mV to -60mV at pH values ​​of composition 11-12. It is understood that the zeta potential of the first silica abrasive particles in the composition at a pH of 11-12 can be arbitrarily combined. For example, the first silica abrasive particles in the composition at a pH of 11-12 have a value of -5mV to -17mV.

[0038] The second type of silica abrasive particles are irregularly shaped abrasive particles, that is, fumed silica abrasive particles are irregularly shaped abrasive particles. Figure 2 A scanning electron microscope image of fumed silica abrasive grains with an average particle size of 155 nm, provided according to an embodiment of this application, is shown. Figure 2 As shown, unlike spherical or round particles, secondary silica abrasive particles exhibit significant geometric asymmetry and structural complexity in their microscopic morphology. Their surfaces and edges, under microscopic observation (such as SEM or TEM images), reveal numerous non-circular, rough, serrated, angular, or fractured features. Specifically, a considerable proportion (e.g., at least 60%, 70%, or even over 80%) of the identifiable surfaces of these particles are flat, angular, or uneven, with edges often exhibiting linear, angular, or fragmented characteristics rather than smooth, continuous curved surfaces. This highly irregular structure originates from the synthesis process of fumed silica—formed through the high-temperature flame hydrolysis reaction of silicon tetrachloride or silanes. This process leads to the rapid aggregation and solidification of primary particles into three-dimensional network, chain-like, or porous secondary particles, thereby endowing them with high specific surface area, strong adsorption capacity, and high surface chemical activity. Secondary silica abrasive grains not only enhance mechanical cutting during polishing through their sharp edges and rough surfaces, but also increase chemical reactivity with the silica surface through abundant surface silanol groups (Si-OH), thereby significantly improving material removal rates. However, when used alone, their irregular morphology may lead to localized stress concentration, increasing the risk of surface defects. Currently, high-performance irregular fumed silica has been commercialized and is available from several specialized manufacturers, such as Tokuyama Corporation of Japan, OCI Company of South Korea, and Cabot Corporation of the United States.

[0039] In some embodiments, the average particle size range of the dispersed second silica abrasive particles in the composition can be 50 nm-300 nm. In some embodiments, the average particle size range of the dispersed second silica abrasive particles in the composition can be 100 nm-200 nm. In some embodiments, the average particle size range of the dispersed second silica abrasive particles in the composition can be 120 nm-180 nm. Further, the average particle size range of the second silica abrasive particles can be 50 nm-60 nm, 60 nm-70 nm, 70 nm-80 nm, 80 nm-90 nm, 90 nm-100 nm, 100 nm-110 nm, 110 nm-120 nm, 120 nm-130 nm, 130 nm-140 nm, 140 nm-150 nm, 150 nm-160 nm, 160 nm-170 nm.

[0040] 170nm-180nm, 180nm-190nm, 190nm-200nm, 200nm-210nm, 210nm-220nm,

[0041] The average particle size range of the second silica abrasive grains can be 220nm-230nm, 230nm-240nm, 240nm-250nm, 250nm-260nm, 260nm-270nm, 270nm-280nm, 280nm-290nm, or 290nm-300nm. Furthermore, the average particle size range of the second silica abrasive grains can be a combination of any of the above ranges, such as 50nm-100nm, 80nm-120nm, etc. It is understood that the average particle size of the second silica abrasive grains can be obtained through dynamic light scattering measurement (e.g., using a Malvern Mastersizer S from Malvern Instruments).

[0042] The second silica abrasive grains in the composition have a zeta potential of -1 mV to -60 mV at pH values ​​of 11-12. In some embodiments, the second silica abrasive grains in the composition have a zeta potential of -10 mV to -40 mV at pH values ​​of 11-12. Furthermore, the second silica abrasive particles in the composition have zeta potentials of -1mV to -5mV, -5mV to -7mV, -7mV to -10mV, -10mV to -15mV, -15mV to -17mV, -17mV to -20mV, -20mV to -25mV, -25mV to -27mV, -27mV to -30mV, -30mV to -35mV, -35mV to -37mV, -37mV to -40mV, -40mV to -45mV, -45mV to -47mV, -47mV to -50mV, -50mV to -55mV, -55mV to -57mV, and -57mV to -60mV at pH values ​​of composition 11-12. It is understood that the zeta potential of the second silica abrasive particles in the composition at pH values ​​of 11-12 can be arbitrarily combined. For example, the second silica abrasive particles in the composition at pH values ​​of 11-12 have a value of -5mV to -17mV.

[0043] The composition includes a liquid carrier. The liquid carrier can contain other components of the composition besides the liquid carrier itself, suspending these components in the liquid carrier and allowing them to contact the substrate for polishing. The liquid carrier can be an aqueous carrier, or any component suitable for suspending abrasive particles and chemical additives. The liquid carrier can be one of water, ethers (such as dioxane and tetrahydrofuran), and alcohols (such as methanol and ethanol), or a combination of water, ethers (such as dioxane and tetrahydrofuran), and alcohols (such as methanol and ethanol). When the liquid carrier is a combination of multiple components, the liquid carrier contains at least 50 wt% water, for example, the aqueous carrier contains 50 wt%, 70 wt%, 90 wt%, 95 wt%, or 99 wt% water. The liquid carrier is water. Further, the water is deionized water.

[0044] The composition also includes a polishing aid. The polishing aid is dissolved in a liquid carrier. The polishing aid interacts with the first and second silica abrasive grains, effectively regulating the pH and dispersion stability of the polishing solution during chemical mechanical polishing. Furthermore, its chemically active components react moderately with the monocrystalline silicon surface, softening the surface material and thus enhancing the cutting efficiency of the abrasive grains, significantly improving material removal rate. Simultaneously, the polishing aid forms a uniform protective film on the monocrystalline silicon wafer surface, reducing surface defects such as scratches and pits, effectively improving surface smoothness and gloss, and achieving high-quality ultra-precision polishing results. This interaction can be based on, for example, hydrogen bonds, van der Waals forces, electrostatic forces, etc. The polishing aid can be any component suitable for use as, for example, a removal rate promoter, polishing rate inhibitor, surfactant, thickener, regulator, complexing agent, chelating agent, biocidal agent, dispersant, oxidizing agent, film-forming agent, etching inhibitor, catalyst, terminating compound, dissolution inhibitor, or a combination thereof.

[0045] Polishing aids include surfactants. Surfactants in the composition can effectively reduce the surface roughness of monocrystalline silicon substrates. Specifically, surfactant molecules can adsorb onto the silicon wafer surface and the interface between silicon oxide abrasive particles through hydrogen bonding, electrostatic interactions, or hydrophobic interactions. The directional alignment of hydrophilic and hydrophobic groups at the interface reduces the surface tension at the liquid-solid interface, promotes uniform spreading of the composition on the silicon wafer surface, and enhances the wetting and penetration ability of micro-area uneven structures. Simultaneously, when surfactants adsorb onto the surface of silicon oxide abrasive particles, they can change the surface charge and provide steric hindrance, helping to disperse the silicon oxide abrasive particles, preventing agglomeration, ensuring uniform action of the silicon oxide abrasive particles on the silicon wafer surface, and reducing scratches and micro-damage caused by localized concentrated cutting. Furthermore, surfactants can moderately inhibit over-etching, balancing chemical action and mechanical polishing, thereby obtaining a smoother, flatter surface morphology, significantly reducing surface roughness, and improving the ultra-precision machining quality of monocrystalline silicon substrates.

[0046] Surfactants include at least one of nonionic or cationic surfactants. Nonionic surfactants include alkylphenol polyoxyethylene ethers. Alkylphenol polyoxyethylene ether molecules have an amphiphilic structure, with hydrophobic groups consisting of alkyl-substituted benzene rings and hydrophilic groups consisting of polyoxyethylene chains. This amphiphilic structure endows them with surface activity, enabling them to be directionally adsorbed onto the surface of silicon oxide abrasive grains or silicon wafers in the composition. During chemical mechanical polishing (CMP), the hydrophobic groups of alkylphenol polyoxyethylene ethers adhere to the surface of silicon oxide abrasive grains or monocrystalline silicon substrates. The hydrophilic groups extend into the aqueous phase, forming a spatially stable layer that effectively prevents the agglomeration of silicon oxide abrasive grains and improves dispersion stability. Simultaneously, the surfactant reduces the surface tension of the polishing solution, enhancing the wetting and penetration ability of the composition onto the micro-uneven structures of the silicon wafer surface. This allows the chemical action and mechanical abrasion to be more uniformly concentrated in the raised areas, thereby promoting surface planarization and significantly reducing surface roughness.

[0047] In the specific chemical structure of the alkylphenol polyoxyethylene ether, the number of carbon atoms m of the alkyl group can be 2 to 20. In some embodiments, the number of carbon atoms m of the alkyl group can be 3 to 12. For example, the number of carbon atoms m of the alkyl group can be any integer from 2 to 20, such as ethyl (m=2), butyl (m=4), octyl (m=8), nonyl (m=9), or dodecyl (m=12), etc.

[0048] The alkylphenol polyoxyethylene ether has a degree of polymerization n of 5 to 200 in its specific chemical structure. In some embodiments, the degree of polymerization n can be 5-100. For example, the degree of polymerization n (i.e., the average number of ethylene oxide units added) can be any integer from 5 to 200, such as n=9 (low hydrophilicity), n=20 (medium hydrophilicity), n=40, n=100, or n=150 (high hydrophilicity). The alkylphenol polyoxyethylene ether can be any combination of atomic number and degree of polymerization. The alkylphenol polyoxyethylene ether obtained by combination can cover a variety of compounds, such as octylphenol polyoxyethylene (9) ether (m=8, n=9), nonylphenol polyoxyethylene (40) ether (m=9, n=40), dodecylphenol polyoxyethylene (100) ether (m=12, n=100), or ethylphenol polyoxyethylene (200) ether (m=2, n=200), etc.

[0049] Alkylphenol polyoxyethylene ethers include at least one of octylphenol polyoxyethylene ether, heptaphenol polyoxyethylene ether, hexylphenol polyoxyethylene ether, decylphenol polyoxyethylene ether, and nonylphenol polyoxyethylene ether. That is, alkylphenol polyoxyethylene ethers can include one of octylphenol polyoxyethylene ether, heptaphenol polyoxyethylene ether, hexylphenol polyoxyethylene ether, decylphenol polyoxyethylene ether, and nonylphenol polyoxyethylene ether, or a combination of any two or more of octylphenol polyoxyethylene ether, heptaphenol polyoxyethylene ether, hexylphenol polyoxyethylene ether, decylphenol polyoxyethylene ether, and nonylphenol polyoxyethylene ether.

[0050] In some embodiments, the alkylphenol polyoxyethylene ether is nonylphenol polyoxyethylene ether. In some embodiments, the nonylphenol polyoxyethylene ether includes at least one of nonylphenol polyoxyethylene (4) ether, nonylphenol polyoxyethylene (6) ether, nonylphenol polyoxyethylene (7) ether, nonylphenol polyoxyethylene (9) ether, nonylphenol polyoxyethylene (10) ether, nonylphenol polyoxyethylene (14) ether, nonylphenol polyoxyethylene (15) ether, nonylphenol polyoxyethylene (18) ether, nonylphenol polyoxyethylene (30) ether, nonylphenol polyoxyethylene (40) ether, and nonylphenol polyoxyethylene (50) ether.

[0051] The main difference between nonylphenol polyoxyethylene (4) ether, nonylphenol polyoxyethylene (6) ether, nonylphenol polyoxyethylene (7) ether, nonylphenol polyoxyethylene (9) ether, nonylphenol polyoxyethylene (10) ether, nonylphenol polyoxyethylene (14) ether, nonylphenol polyoxyethylene (15) ether, nonylphenol polyoxyethylene (18) ether, nonylphenol polyoxyethylene (30) ether, nonylphenol polyoxyethylene (40) ether and nonylphenol polyoxyethylene (50) ether lies in the length of their polyoxyethylene chains (i.e., the number of ethylene oxide units, EO number).

[0052] In some embodiments, nonylphenol polyoxyethylene ether is nonylphenol polyoxyethylene (40) ether, that is, nonylphenol polyoxyethylene ether with an EO number of 40.

[0053] Cationic surfactants include 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-halogenammonium. The molecular structure of 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-halogenammonium contains a positively charged quaternary ammonium head group and two long, hydrophobic alkyl chains linked by ether bonds. The quaternary ammonium head group also has terminal hydroxyl groups to enhance hydrophilicity, resulting in a distinct amphiphilic character. During chemical mechanical polishing (CMP), this surfactant can adsorb onto negatively charged silica abrasive grains or the surface of single-crystal silicon wafers through electrostatic and hydrophobic interactions, effectively reducing liquid-solid interfacial tension and enhancing the wetting and spreading ability of the composition. Simultaneously, the adsorption layer of this surfactant creates steric hindrance and electrostatic repulsion, preventing silica abrasive grain aggregation, improving dispersion stability, and reducing localized scratches or uneven grinding caused by particle aggregation. In addition, the surfactant can form a moderate protective layer on the silicon wafer surface, inhibit excessive corrosion in the recessed areas, and promote the selective removal of the protrusions, thereby improving the surface planarization effect and significantly reducing surface roughness.

[0054] In 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-ammonium halide, when the alkyl group is dodecyl, the hydroxyalkyl group is 2-hydroxyethyl, and the counterion is bromide, 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-ammonium halide is 2,3-bis(dodecyloxy)-N-(2-hydroxyethyl)-N,N-dimethylpropane-1-bromide. For ease of description, 2,3-bis(dodecyloxy)-N-(2-hydroxyethyl)-N,N-dimethylpropane-1-bromide will be abbreviated as BNAB in the following text.

[0055] When used, the surfactant accounts for 0.0001 wt.% to 2.0 wt.% of the composition by weight. In some embodiments, the surfactant accounts for 0.001 wt.% to 0.5 wt.% of the composition by weight. Further, the surfactant accounts for 0.0001 wt.% to 0.001 wt.%, 0.001 wt.% to 0.005 wt.%, 0.005 wt.% to 0.01 wt.%, 0.01 wt.% to 0.1 wt.%, 0.1 wt.% to 0.2 wt.%, 0.3 wt.%, 0.3 wt.% to 0.4 wt.%, and 0.4 wt.% to 0.5 wt.% by weight. It is understood that the above-mentioned ranges of surfactant weight percentages can be arbitrarily combined, for example, the surfactant accounts for 1.0 wt.% to 2.0 wt.% of the composition by weight.

[0056] The polishing aid also includes a chelating agent. This chelating agent effectively complexes metal ions in the composition during the CMP process, preventing metal ions from depositing on the polishing interface or the surface of silicon oxide abrasive grains and thus passivating the reactivity. This maintains and enhances the continuity of the polishing process, helps improve the material removal rate of the substrate surface, and simultaneously improves the uniformity and surface quality of the polishing. The chelating agents include dicarboxylic acids, polycarboxylic acids, amino acids, aminocarboxylic acids, aminopolycarboxylic acids, phosphates, polyphosphates, aminophosphonic acids, phosphonocarboxylic acids, and combinations thereof.

[0057] The dicarboxylic acids include at least one of oxalic acid, malonic acid, succinic acid, maleic acid, phthalic acid, tartaric acid, aspartic acid, or glutamic acid. The polycarboxylic acids include at least one of citric acid or butanetetracarboxylic acid. The amino polycarboxylic acids include ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenediaminetetraacetic acid (EGTA), diethylenetriaminepentaacetic acid (DTPA), diaminohydroxypropanetetraacetic acid (DTPA-OH), triethylenetetraaminehexaacetic acid (TTHA), iminodiacetic acid (IDA), nitrotriacetic acid (NTA), bis(aminophenoxyethanetetraacetic acid) (BAPTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), nicotinamide, ethylenediaminedihydroxyphenylacetic acid (EDDHA), and combinations thereof. Aminophosphonic acids include ethylenediaminetetra(methylenephosphonic acid) (EDTMP), aminotri(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid) (DTPMP), and combinations thereof.

[0058] In some embodiments, the chelating agent is an aminopolycarboxylic acid. In some embodiments, the chelating agent is at least one selected from ethylenediaminetetraacetic acid (EDTA), diaminohydroxypropanetetraacetic acid (DTPA-OH), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenediaminetetraacetic acid (EGTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraaminehexaacetic acid (TTHA), diethylenetriaminepenta (methylenephosphonic acid) (DTPMP), and ethylenediaminetetra(methylenephosphonic acid) (EDTMP).

[0059] When used, the chelating agent accounts for 0.01 wt.% to 5.0 wt.% of the composition by weight. In some embodiments, the chelating agent accounts for 0.08 wt.% to 2.0 wt.% of the composition by weight. Further, the chelating agent accounts for 0.01 wt.% to 0.5 wt.%, 0.5 wt.% to 0.8 wt.%, 0.5 wt.% to 1 wt.%, 1 wt.% to 1.5 wt.%, 1.5 wt.% to 2 wt.%, 2 wt.% to 2.5 wt.%, 2.5 wt.% to 3 wt.%, 3 wt.% to 3.5 wt.%, 3.5 wt.% to 4 wt.%, 4 wt.% to 4.5 wt.%, and 4.5 wt.% to 5 wt.%. It is understood that the above-mentioned ranges of the chelating agent's weight percentage in the composition can be arbitrarily combined, for example, the chelating agent accounts for 1.0 wt.% to 2.0 wt.% of the composition by weight.

[0060] Polishing aids also include removal rate enhancers. These remove rate enhancers include nitrogen-containing compounds. Nitrogen-containing compounds can adsorb onto the surface of single-crystal silicon via amino groups in their molecules, promoting the hydrolysis of surface Si-H groups and simultaneously inducing polarization of adjacent Si-Si bonds, weakening them and making them more susceptible to nucleophilic attack by OH- or H2O, forming an oxide layer that is subsequently removed by abrasive mechanical processes. Furthermore, nitrogen-containing compounds can enhance the interfacial reaction activity between silicon oxide abrasive grains and the silicon wafer, thereby significantly improving the material removal rate.

[0061] Nitrogen-containing compounds include compounds having at least one amino group, two amino groups, three amino groups, or more than three amino groups (e.g., five amino groups). Further, nitrogen-containing compounds include linear primary diamines, piperazine compounds, guanidine compounds, choline, alkanolamines, or combinations thereof. The linear primary diamines include diaminomethane, 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-diaminodecane, 1,11-undecanediamine, 1,12-dodecanediamine, and combinations thereof. Piperazine compounds include piperazine, bisaminopropylpiperazine, hydroxyethylpiperazine, aminoethylpiperazine, bishydroxyethylpiperazine, methylbenzylpiperazine, tert-butyloxycarbonylpiperazine, methoxyphenylpiperazine dihydrochloride, piperazine carboxylate, methylpiperazine, ethylpiperazine, butylpiperazine, formylpiperazine, dimethylpiperazine, bromomethylpiperazine, aminomethylpiperazine, isopropylpiperazine, methoxyethylpiperazine, cyclopropylmethylpiperazine, benzylpiperazine, benzyloxycarbonylpiperazine, acetylpiperazine, cyclohexylpiperazine, piperazine methanol, piperazine formaldehyde, and combinations thereof. Guanidine compounds include guanidine, guanidine derivatives, guanidine salts, and combinations thereof. Further, guanidine compounds include guanidine carbonate, guanidine hydrochloride, arginine, creatine, and combinations thereof. Alkaneolamines include ethanolamine, diethanolamine, triethanolamine, aminoethylethanolamine, aminoethoxyethanol, aminoethylisopropanolamine, dimethylethanolamine, diethylethanolamine, aminoethylmethylethanolamine, aminopropanol, methylaminoethanol, aminobutanol, propanol, isopropylaminoethanol, butylaminopropanol, tert-butylaminoethanol, dimethylaminobutylaminoethanol, dimethylaminohexanol, aminomethylpropylene glycol, methyldiethanolamine, diisopropanolamine, methoxyethanol ethyldiethanolamine, aminoethylethanol, butyldiethanolamine, triisopropanolamine, dimethylaminopropanol, butylaminoethanol, tert-butylaminoethanol, diethylethanolamine, dimethylaminomethylpropanol, diisopropylaminoethanol, dibutylaminoethanol, dimethylaminohexanol, aminomethylpropylene glycol, methyldiethanolamine, diisopropanolamine, dimethylaminoethoxyethanol, ethyldiethanolamine, butyldiethanolamine, triisopropanolamine, and combinations thereof.

[0062] In addition to the compounds mentioned above, nitrogen-containing compounds also include linear aliphatic polyamines. These linear aliphatic polyamines include diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine, polyethyleneimine (PEI), and combinations thereof.

[0063] In this scheme, linear aliphatic polyamines are preferred as removal rate enhancers among a variety of removal rate enhancers.

[0064] When used, the removal rate enhancer accounts for 0.01 wt.% to 7.0 wt.% of the composition by weight. In some embodiments, the removal rate enhancer accounts for 0.1 wt.% to 4.0 wt.% of the composition by weight. Further, the removal rate enhancer accounts for 0.01 wt.% to 0.5 wt.%, 0.5 wt.% to 0.8 wt.%, 0.5 wt.% to 1 wt.%, 1 wt.% to 1.5 wt.%, 1.5 wt.% to 2 wt.%, 2 wt.% to 2.5 wt.%, 2.5 wt.% to 3 wt.%, 3 wt.% to 3.5 wt.%, 3.5 wt.% to 4 wt.%, 4 wt.% to 4.5 wt.%, 4.5 wt.% to 5 wt.%, 5 wt.% to 5.5 wt.%, 5.5 wt.% to 6 wt.%, 6 wt.% to 6.5 wt.%, and 6.5 wt.% to 7 wt.%. It is understood that the above-mentioned ranges of removal rate enhancer in the composition can be arbitrarily combined, for example, the removal rate enhancer accounts for 1.0 wt.% to 2.0 wt.%.

[0065] The polishing aid also includes a pH adjuster. This pH adjuster helps the composition achieve a suitable pH. The pH adjuster includes organic bases, inorganic bases, or combinations thereof.

[0066] The inorganic bases include at least one of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkaline earth metal carbonates, alkali metal phosphates, alkaline earth metal phosphates, or ammonium compounds. Alkali metal hydroxides include at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide. Alkaline earth metal hydroxides include at least one of magnesium hydroxide, calcium hydroxide, and beryllium hydroxide. Alkali metal carbonates include at least one of potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, and lithium bicarbonate. Alkali earth metal carbonates include at least one of magnesium carbonate, calcium carbonate, and beryllium carbonate. Alkali metal phosphates include at least one of tripotassium phosphate, trisodium phosphate, dipotassium phosphate, and disodium phosphate. Alkali earth metal phosphates include at least one of magnesium phosphate, calcium phosphate, and beryllium phosphate. Ammonium compounds include at least one of ammonium carbonate, ammonium bicarbonate, and ammonium hydroxide.

[0067] Organic bases include at least one of aliphatic amines, aromatic amines, and quaternary ammonium hydroxides. Aliphatic amines include at least one of ethylamine, diethylamine, and ethanolamine. Aromatic amines include at least one of aniline and pyridine. Quaternary ammonium hydroxides include at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH).

[0068] In this scheme, the preferred pH adjuster is an alkali metal hydroxide, a quaternary ammonium hydroxide, an alkali metal carbonate, or a combination thereof. Further, the pH adjuster is selected from: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, or any combination thereof.

[0069] When used, the pH adjuster accounts for 0.01 wt.% to 8.0 wt.% of the composition by weight. In some embodiments, the pH adjuster accounts for 0.1 wt.% to 5 wt.% of the composition by weight. In some embodiments, the pH adjuster accounts for 0.5 wt.% to 3 wt.% of the composition by weight. Further, the pH adjuster accounts for 0.01 wt.% to 0.5 wt.%, 0.5 wt.% to 0.8 wt.%, 0.5 wt.% to 1 wt.%, 1 wt.% to 1.5 wt.%, 1.5 wt.% to 2 wt.%, 2 wt.% to 2.5 wt.%, 2.5 wt.% to 3 wt.%, 3 wt.% to 3.5 wt.%, 3.5 wt.% to 4 wt.%, 4 wt.% to 4.5 wt.%, 4.5 wt.% to 5 wt.%, 5 wt.% to 5.5 wt.%, 5.5 wt.% to 6 wt.%, 6 wt.% to 6.5 wt.%, 6.5 wt.% to 7 wt.%, 7 wt.% to 7.5 wt.%, and 7.5 wt.% to 8 wt.% of the composition by weight. It is understood that the weight ratio range of the pH adjuster in the composition can be arbitrarily combined, for example, the weight ratio of the pH adjuster in the composition is 1.0 wt.% to 2.0 wt.%.

[0070] The polishing aid also includes a pH buffer. The pH buffer helps maintain a suitable pH value in the composition. Further, the pH adjuster and pH buffer work together to adjust the pH value of the composition. The pH buffer can be any suitable buffer. For example, the pH buffer can be a carbonate, bicarbonate, phosphate, borate, organic buffer, or a combination thereof. Carbonates include sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate, calcium carbonate, magnesium carbonate, and combinations thereof. Bicarbonates include sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, and combinations thereof. Phosphates include sodium phosphate, potassium phosphate, ammonium phosphate, and combinations thereof. Borates include sodium borate, potassium borate, and combinations thereof. Organic buffers include tris(hydroxymethyl)aminomethane (TRIS), sodium acetate, potassium acetate, ammonium acetate, sodium citrate, potassium citrate, ammonium citrate, and combinations thereof. In this embodiment, inorganic carbonates are preferred as pH buffers. Further, sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate, carbonate, and magnesium carbonate are preferred as pH buffers.

[0071] When used, the pH buffer accounts for 0.01 wt.% to 8.0 wt.% of the composition by weight. In some embodiments, the pH buffer accounts for 0.1 wt.% to 5 wt.% of the composition by weight. In some embodiments, the pH buffer accounts for 0.5 wt.% to 3 wt.% of the composition by weight. Further, the pH buffer accounts for 0.01 wt.% to 0.5 wt.%, 0.5 wt.% to 0.8 wt.%, 0.5 wt.% to 1 wt.%, 1 wt.% to 1.5 wt.%, 1.5 wt.% to 2 wt.%, 2 wt.% to 2.5 wt.%, 2.5 wt.% to 3 wt.%, 3 wt.% to 3.5 wt.%, 3.5 wt.% to 4 wt.%, 4 wt.% to 4.5 wt.%, 4.5 wt.% to 5 wt.%, 5 wt.% to 5.5 wt.%, 5.5 wt.% to 6 wt.%, 6 wt.% to 6.5 wt.%, 6.5 wt.% to 7 wt.%, 7 wt.% to 7.5 wt.%, and 7.5 wt.% to 8 wt.% of the composition by weight. It is understood that the above-mentioned range of pH buffers in the composition by weight can be arbitrarily combined, for example, the pH buffer in the composition by weight is 1.0 wt.% to 2.0 wt.%.

[0072] With the adjustment of a pH adjuster and a pH buffer, the composition has a suitable pH value. In some embodiments, the composition has a pH value greater than 7 when used, i.e., the composition is alkaline. In some embodiments, the composition has a pH value of 9 to 12 when used. In some embodiments, the composition has a pH value of 10 to 11 when used. In some embodiments, the composition has a pH value of 11 to 12 when used. Further, the composition has a pH value between 9 and 10, and between 10 and 11 when used.

[0073] Secondly, this application also provides a polishing method for a single-crystal silicon substrate. The method includes the following steps: (a) providing the above-described chemical mechanical polishing composition; (b) contacting the single-crystal silicon substrate with the chemical mechanical polishing composition and a polishing pad; (c) moving the polishing pad relative to the single-crystal silicon substrate, with the chemical mechanical polishing composition located in between; and (d) removing at least a portion of the single-crystal silicon substrate. The method may optionally include other steps.

[0074] The composition can be prepared using suitable techniques known to those skilled in the art. As described above, the silica abrasive particles and other components can be added to the liquid carrier in any order and in suitable amounts to achieve the desired concentration. The silica abrasive particles and other components can be mixed and stirred in the liquid carrier. The pH value can be adjusted using the pH adjuster and pH buffer described above to obtain and maintain the desired pH. The silica abrasive particles and other components can be added at any time before use or during CMP treatment.

[0075] The composition can be provided as a single-part system, a two-part system, or a multi-part system. For example, as a two-part system, the first part may include silica abrasive particles, and the second part may include one or more other components. The first and second parts can be mixed at any time before or during the CMP treatment.

[0076] The following are specific embodiments of the compositions designed according to the above disclosure. It should be understood that the following embodiments are merely illustrative of the compositions and polishing methods disclosed above, and the specific implementation methods and parameters used are only one or more of the numerous parameters and methods described above. Those skilled in the art can use other parameters to perform chemical mechanical polishing according to the above methods without departing from the core spirit of the disclosure.

[0077]

Measurement

[0078] Polishing process: All experiments were conducted using a KIZI polishing machine (Dongguan Jinyan Precision Grinding Machinery Manufacturing Co., Ltd.). The polished wafers were 6-inch diameter p-type silicon wafers. The polishing pads were Suba800 (Nitta Haas). The polishing disc speed was 93 rpm, the polishing head speed was 87 rpm, the pressure was 2.5 psi, the polishing fluid flow rate was 140 ml / min, and the polishing time was 5 minutes. After polishing, the wafers were cleaned with a PVA brush and deionized water.

[0079] Removal Rate (RR) Measurement: The material removal rate of the silicon wafer is measured using an electronic scale and calculated based on the weight difference before and after polishing.

[0080] Average particle size measurement: Average particle size is measured by dynamic light scattering (e.g., using Malvern MastersizerS from Malvern Instruments).

[0081] Surface roughness (Ra) measurement: The surface roughness (Ra) of the polished silicon wafer was measured at four measurement points, including the center and 20 mm from the edge of the silicon wafer, using an NX20 (ParkSystems). Surface roughness is the arithmetic mean of the absolute deviations of the profile height from the average height.

[0082] Zeta potential measurement: The zeta potential of the particles in the composition was measured using a Mastersizer S (Malvern Instruments).

[0083] Scratch measurement: Scratch was measured using 10 wafers. A Candela CS10 (KLA-Tencor) was used to inspect surface scratches on the polished wafers. The number of wafers with scratches among these 10 wafers was counted.

[0084] Example 1

[0085] Compositions A1-A6 and E1-E4 contain 0.8 wt% tetramethylammonium hydroxide (TMAH), 1.2 wt% potassium carbonate, 1.2 wt% diethylenetriamine (DETA), and 0.2 wt% diethylenetriaminepentaacetic acid (DTPA). The pH value is 11.5. Furthermore, compositions A1-A6 and E1-E4 also contain silica abrasive particles, including fumed silica and colloidal silica. The average particle size and concentration of the fumed silica and colloidal silica are shown in Table 1, with a total concentration of 10 wt%.

[0086] Table 1

[0087]

[0088] in conclusion:

[0089] (1) Compared with A3, A1, which contains colloidal silica abrasive particles, exhibits a lower surface roughness Ra, but also a lower material removal rate RR. Correspondingly, compared with A1, A3, which contains fumed silica abrasive particles, exhibits a higher material removal rate RR, but also a higher surface roughness Ra.

[0090] (2) Compared with E1, A2, which has a higher content of fumed silica abrasive particles, has a higher material removal rate RR, but also a higher surface roughness.

[0091] (3) Compared with E2, E3 and E4, A4, A5 and A6, which have higher average particle size of fumed silica, have higher material removal rates, but also higher surface roughness Ra.

[0092] (4) Compared with A4, A5 and A6, E2-E4 has a smaller average particle size of fumed silica, exhibiting a comparable material removal rate RR and a lower surface roughness Ra.

[0093] Example 2

[0094] Compositions A7, A8, and E5 contain 1.2 wt% tetramethylammonium hydroxide (TMAH), 1 wt% potassium carbonate, 0.8% triethylenetetramine (TETA), and 0.2 wt% diethylenetriaminepentaacetic acid (DTPA). The pH value is 11.5. Furthermore, compositions A7, A8, and E5 also contain silica abrasive particles, including fumed silica and colloidal silica. The average particle size and concentration of the fumed silica and colloidal silica are shown in Table 2, with a total concentration of 10 wt%.

[0095] Table 2

[0096]

[0097] in conclusion:

[0098] (1) Compared with A8, A7, which contains colloidal silica abrasive particles, has no scratches.

[0099] (2) Compared with A7 and A8, E5, which contains both colloidal silica abrasive particles and fumed silica abrasive particles, has no scratches and a higher removal rate.

[0100] Example 3

[0101] Compositions A9-A14 and E6-E8 contain 1 wt% tetramethylammonium hydroxide (TMAH), 1 wt% potassium carbonate, 1 wt% diethylenetriamine (DETA), and 0.15 wt% ethylenediaminetetraacetic acid (EDTA). The pH value is 11.5. Compositions A9-A14 and E6-E8 also contain 0.01 wt% of a surfactant, as shown in Table 3. Furthermore, compositions A9-A14 and E6-E8 contain silica abrasive particles, including fumed silica and colloidal silica. The average particle size and concentration of the fumed silica and colloidal silica are shown in Table 3, with a total concentration of 10 wt%.

[0102] Table 3

[0103]

[0104]

[0105] in conclusion:

[0106] (1) Compared with A12-A14, the composition A9-A11, which contains only colloidal silica abrasive particles, exhibits a lower removal rate but has a lower surface roughness Ra and no scratches.

[0107] (2) Compared with A9 which contains only colloidal silica, component E6, which contains both colloidal silica and fumed silica, exhibits a higher removal rate and lower surface roughness compared with A9 which contains only silica and A14 which contains only fumed silica.

[0108] (3) Compared with A9, A12 and E6, the surfactant-containing compositions A10-A11, A13-A14 and E7-E8 exhibited lower surface roughness.

[0109] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0110] In summary, after reading this detailed disclosure, those skilled in the art will understand that the foregoing detailed disclosure may be presented by way of example only and may not be restrictive. Although not explicitly stated herein, those skilled in the art will understand that this specification requires various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be made by this specification and are within the spirit and scope of the exemplary embodiments described herein.

[0111] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, "an embodiment," "an embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is to be emphasized and understood that two or more references to "an embodiment" or "an embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Moreover, specific features, structures, or characteristics may be suitably combined in one or more embodiments of this specification.

[0112] It should be understood that in the foregoing description of the embodiments in this specification, various features are combined in a single embodiment, drawing, or description for the purpose of simplifying the description and to aid in understanding a feature. However, this does not mean that the combination of these features is necessary, and those skilled in the art may extract some features as individual embodiments when reading this specification. That is, the embodiments in this specification can also be understood as an integration of multiple sub-embodiments. It is also valid when each sub-embodiment contains fewer than all the features of a single foregoing disclosed embodiment.

[0113] Every patent, patent application, publication of a patent application, and other material, such as articles, books, specifications, publications, documents, and literature (excluding any related historical examination documents), cited in this disclosure is incorporated herein for all purposes, including, for example, in the specification and claims of this disclosure. However, in the event of any inconsistency or conflict between the descriptions, definitions, and / or terms used in the foregoing and those used in this disclosure, the descriptions, definitions, and / or terms used in this disclosure shall prevail.

[0114] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments described in this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can implement the applications described in this specification using alternative configurations based on the embodiments in this specification. Therefore, the embodiments in this specification are not limited to the embodiments precisely described in the applications.

Claims

1. A chemical mechanical polishing composition for polishing a single crystal silicon substrate, characterized by comprising: a colloidal silica abrasive; a nonionic surfactant; and a water-soluble organic acid. Comprising: first silica abrasive grains including colloidal silica abrasive grains and being spherical in shape with an average particle diameter of 10-150 nm; second silica abrasive grains including fumed silica abrasive grains and being irregular in shape with an average particle diameter of 50-300 nm; and a polishing aid that cooperates with the first silica abrasive grains and the second silica abrasive grains to improve polishing quality and material removal rate of the single crystal silicon substrate. The mass ratio of the first silica abrasive grains and the second silica abrasive grains ranges from 3:7 to 9:1, wherein the first silica abrasive grains account for 30-90% of the total abrasive grains in terms of mass ratio, and the second silica abrasive grains account for 10-70% of the total abrasive grains in terms of mass ratio.

2. The composition of claim 1, wherein, The mass ratio of the first silica abrasive grains and the second silica abrasive grains ranges from 4:6 to 8:2, wherein the first silica abrasive grains account for 40-80% of the total abrasive grains in terms of mass ratio, and the second silica abrasive grains account for 20-60% of the total abrasive grains in terms of mass ratio.

3. The composition of claim 1, wherein, The polishing aid includes a surfactant, and the surfactant includes at least one of a nonionic surfactant or a cationic surfactant.

4. The composition of claim 1, wherein, The nonionic surfactant includes an alkylphenol polyoxyethylene ether.

5. The composition of claim 4, wherein, The number of carbon atoms m of the alkyl group in the alkylphenol polyoxyethylene ether ranges from 2 to 20, and the degree of polymerization n ranges from 5 to 200, and the alkylphenol polyoxyethylene ether can be any combination of the number of atoms and the degree of polymerization.

6. The composition of claim 5, wherein, The alkylphenol polyoxyethylene ether includes at least one of an octylphenol polyoxyethylene ether, a heptylphenol polyoxyethylene ether, a hexylphenol polyoxyethylene ether, a decylphenol polyoxyethylene ether, and a nonylphenol polyoxyethylene ether.

7. The composition of claim 6, wherein, The alkylphenol polyoxyethylene ether includes a nonylphenol polyoxyethylene ether.

8. The composition of claim 6, wherein, The cationic surfactant includes 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-halide ammonium.

9. The composition of claim 4, wherein, The 2,3-bis(alkyloxy)-N-(ω-hydroxyalkyl)-N,N-dimethylpropane-1-halide ammonium includes 2,3-bis(dodecyloxy)-N-(2-hydroxyethyl)-N,N-dimethylpropane-1-bromide.

10. The composition of claim 9, wherein, The method utilizes the composition according to any one of claims 1-10 to polish a single crystal silicon substrate.

11. A polishing method for a single crystal silicon substrate, characterized by, ​

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