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 chemical mechanical polishing composition is used for polishing a monocrystalline silicon substrate, and comprises cerium oxide abrasive particles; an oxidant; and a catalyst which is a nitrogen-based non-metallic compound. Compared with silicon dioxide abrasive particles, the cerium oxide abrasive particles are easier to clean from the surface of monocrystalline silicon. Meanwhile, an oxidizing agent and a catalyst are further added into the composition, and the higher material removal rate can be achieved through the combined action of the cerium oxide abrasive particles, the oxidizing agent and the catalyst.

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] Monocrystalline silicon, as a key semiconductor material, is widely used in integrated circuits, solar cells, sensors, and microelectronic devices due to its excellent electrical properties and highly ordered crystal structure. For example, modern central processing units (CPUs), GPU chips, and high-efficiency photovoltaic modules are all based on monocrystalline silicon.

[0003] In the fabrication of monocrystalline silicon, chemical mechanical polishing (CMP) is the core process for achieving atomic-level surface smoothness. Currently, silica nanoparticles are commonly used as abrasives due to their soft texture, which effectively removes surface oxide layers and defects while minimizing scratches or subsurface damage to the silicon wafer. Therefore, they are widely used in the raw material, intermediate, and final polishing stages. However, the surface of silica abrasives is rich in hydroxyl groups, which easily form strong hydrogen bonds or electrostatic adsorption with the monocrystalline silicon surface. This results in silica abrasives stubbornly adhering to the wafer surface after polishing, making them difficult to completely remove through conventional cleaning. Summary of the Invention

[0004] This application provides a chemical mechanical polishing composition and polishing method for polishing single-crystal silicon substrates. Cerium oxide abrasives are used in this composition to polish the single-crystal silicon substrate. Compared to silicon dioxide abrasives, cerium oxide abrasives are easier to clean from the surface of single-crystal silicon.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, embodiments of this application provide a chemical mechanical polishing composition for polishing a single-crystal silicon substrate, comprising: cerium oxide abrasive particles; an oxidant; and a catalyst, which is a nitrogen-based nonmetallic compound.

[0007] According to some embodiments of this application, the composition does not contain silica abrasive particles.

[0008] According to some embodiments of this application, the cerium oxide abrasive grains are chamfered octahedral cerium oxide abrasive grains.

[0009] According to some embodiments of this application, the cerium oxide abrasive particles have a zeta potential of -12 mV to -60 mV when the pH of the composition is 10-11.

[0010] According to some embodiments of this application, the nitrogen-based nonmetallic compound includes at least one of hydroxylamine, hydroxylamine sulfate, hydroxylamine hydrochloride, hydrazine, hydrazine hydrate, phenylhydrazine, N,N-dimethylamine, triethylamine oxide, sodium azide, or phenyl azide and its derivatives.

[0011] According to some embodiments of this application, the nitrogen-based nonmetallic compound is hydroxylamine.

[0012] According to some embodiments of this application, the oxidant is an inorganic non-metallic compound, which includes at least one of hydrogen peroxide, monopersulfate, diporsulfate, perchlorate, periodate, perborate, perbromate, peroxycarbonate, peroxyurea, diporoxydicarbonate, peroxymonosulfate, peroxydisulfate, perbromic acid, periodic acid, or perchloric acid.

[0013] According to some embodiments of this application, the composition further includes a pH adjuster comprising at least one of tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine), N,N,N',N',N”-pentamethyldiethylenetriamine, N-(2-ethylamino)-1,3-propanediamine, hexamethyl quaternary ammonium hydroxide, N,N'-dimethyl-1,6-hexanediamine, and hexane-1,6-bis(tri-n-butylammonium) dihydrogen phosphate.

[0014] According to some embodiments of this application, the pH adjuster is tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine).

[0015] According to some embodiments of this application, the composition further includes a wetting agent comprising a polyol and not containing a polymer.

[0016] According to some embodiments of this application, the polyol includes at least one of glycerol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol (1,3-butanediol or 1,4-butanediol), hexanediol (2-methyl-2,4-pentanediol), trimethylolpropane, neopentyl glycol, pentaerythritol, sorbitol, mannitol, xylitol, or erythritol.

[0017] According to some embodiments of this application, the composition is free of hydroxyethyl cellulose and polyvinylpyrrolidone.

[0018] 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

[0019] 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.

[0020] Figure 1 A scanning electron microscope image of chamfered octahedral cerium oxide abrasive grains (purchased) provided according to an embodiment of this specification is shown;

[0021] Figure 2 A scanning electron microscope image of chamfered octahedral cerium oxide abrasive grains (prepared) according to an embodiment of this specification is shown; Detailed Implementation

[0022] 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.

[0023] 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.

[0024] 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.

[0025] Considering the following description, these and other features of this specification, as well as the operation and function of related structural elements, and the economy of component assembly and manufacture, can be significantly improved. This description also includes all figures and text in the accompanying drawings, all of which form part of this specification. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0026] Monocrystalline silicon, as a key semiconductor material, is widely used in integrated circuits (ICs), micro-electro-mechanical 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 GPUs, 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.

[0027] In existing technologies, silica particles are widely used as the abrasive component in polishing slurries, especially dominating the stock polishing and final polishing stages of monocrystalline silicon. The main reason for the widespread use of silica particles is that silica has a relatively low Mohs hardness (approximately 5.5-6.5), far lower than that of monocrystalline silicon (approximately 7). Therefore, it causes less mechanical damage to the monocrystalline silicon substrate during polishing, effectively avoiding defects such as scratches, dislocation extension, and subsurface lattice distortion, thereby ensuring the yield of subsequent photolithography, epitaxy, or thin film deposition processes.

[0028] However, the surface of silica particles is rich in active silanol groups (≡Si-OH). In a typical CMP environment that is near neutral or alkaline (pH>7), these hydroxyl groups dissociate to form negatively charged ≡Si-O- groups. Similarly, a thin oxide layer (SiO2) forms on the surface of single-crystal silicon under oxidizing conditions, also carrying a negative charge. Although like charges should theoretically repel each other, in actual processes, due to local ion shielding effects (such as K+, Na+, etc. counterions compressing the electric double layer), hydrogen bonding, and van der Waals forces, silica particles readily adsorb onto the surface of single-crystal silicon wafers through bridging effects (such as metal ion bridges and hydrated hydrogen bond bridges). This adsorption is not only difficult to completely remove with conventional megasonic cleaning or chemical rinsing, but it also forms "particle contamination hotspots" on the wafer surface, causing pattern defects (such as bridging and broken lines) during subsequent photolithography, severely reducing chip yield. Furthermore, due to the low hardness of silicon dioxide, it is difficult to generate sufficient shear force to efficiently remove surface reaction products (such as the native oxide layer or damaged layer) when in contact with the silicon wafer surface. Its removal mechanism mainly relies on a slow chemical-dominated process with a weak mechanical contribution, resulting in a low overall material removal rate.

[0029] Therefore, to overcome the inherent defects of silica abrasives, ideal abrasives should possess certain properties, such as moderate hardness—slightly higher than the silica layer but lower than the monocrystalline silicon substrate—so that they can remove surface oxides without damaging the underlying crystals. Another example is tunable surface electrochemistry to reduce adsorption tendency. In other words, the abrasives should have tunable surface charge characteristics within a pH range, enabling them to form stable electrostatic repulsion with the monocrystalline silicon surface and reduce physical adsorption.

[0030] In view of this, this application provides a chemical mechanical polishing composition and a polishing method for polishing single-crystal silicon substrates. In this composition, cerium oxide abrasive grains are used as polishing abrasive grains. Cerium oxide abrasive grains have tunable surface charge characteristics and a hardness higher than the silicon oxide layer but lower than the single-crystal silicon substrate, enabling the removal of the silicon oxide layer without damaging the single-crystal silicon substrate. Simultaneously, an oxidant and a catalyst are also added to the composition. The combined effect of the cerium oxide abrasive grains, oxidant, and catalyst can improve the material removal rate.

[0031] Before describing the specific embodiments in this specification, the application scenarios of this specification will be introduced as follows, wherein the chemical mechanical polishing composition is referred to as the composition.

[0032] 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 interim polishing stage to improve surface planarization efficiency and control interlayer thickness uniformity. 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 (GPUs), 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.

[0033] The composition includes cerium oxide abrasive grains. These cerium oxide abrasive grains provide a combination of chemical reaction and mechanical polishing, removing minute bumps and uneven areas from the surface of a monocrystalline silicon substrate through physical friction, thus planarizing the substrate. Cerium oxide abrasive grains include, but are not limited to, spherical cerium oxide abrasive grains, polyhedral cerium oxide abrasive grains, sheet-like cerium oxide abrasive grains, blocky cerium oxide abrasive grains, needle-like cerium oxide abrasive grains, rod-like cerium oxide abrasive grains, or polycrystalline agglomerated cerium oxide abrasive grains. The polyhedral cerium oxide abrasive grains can be at least one of cubic cerium oxide abrasive grains, octahedral cerium oxide abrasive grains, or chamfered octahedral cerium oxide abrasive grains. It should be noted that the composition does not contain silica abrasive grains. These silica abrasive grains can be any type of silica abrasive grains, such as colloidal silica abrasive grains or fumed silica abrasive grains. This composition fundamentally avoids the problems of traditional silica particles easily adhering to the monocrystalline silicon surface during chemical mechanical polishing, making thorough cleaning difficult, resulting in particle residue and surface defects.

[0034] The composition contains cerium oxide abrasive particles at a weight ratio between 0.1 wt% and 10 wt%. In some embodiments, the composition contains cerium oxide abrasive particles at a weight ratio between 0.5 wt% and 5 wt%. In some embodiments, the composition contains cerium oxide abrasive particles at a weight ratio between 1 and 3 wt%. Furthermore, the weight ratio of cerium oxide abrasive particles in the composition can be selected to be between 0.1wt%-0.5wt%, 0.5wt%-1wt%, 1wt%-1.5wt%, 1.5wt%-2wt%, 2wt%-2.5wt%, 2.5wt%-3wt%, 3wt%-3.5wt%, 3.5wt%-4wt%, 4wt%-4.5wt%, 4.5wt%-5wt%, 5wt%-5.5wt%, 5.5wt%-6wt%, 6wt%-6.5wt%, 6.5wt%-7wt%, 7wt%-7.5wt%, 7.5wt%-8wt%, 8wt%-8.5wt%, 8.5wt%-9wt%, and 9.5wt%-10wt%. It is understood that the above-mentioned range of cerium oxide abrasive particle weight ratio can be arbitrarily combined; for example, the weight ratio of cerium oxide abrasive particles in the composition ranges from 1.5 wt% to 3.5 wt%. It is also understood that the above weight ratio refers to the weight ratio of cerium oxide abrasive particles when the composition is used.

[0035] The cerium oxide abrasive particles in the composition have a zeta potential of -12 mV to -60 mV at a pH of 10-11. In some embodiments, the cerium oxide abrasive particles have a zeta potential of -18 mV to -40 mV at a pH of 10-11. In some embodiments, the cerium oxide abrasive particles have a zeta potential of -20 mV to -35 mV at a pH of 10-11. Furthermore, the cerium oxide abrasive particles in the composition have zeta potentials of -12mV to -15mV, -15mV to -20mV, -20mV to -25mV, -25mV to -30mV, -30mV to -35mV, -35mV to -40mV, -40mV to -45mV, -45mV to -50mV, -50mV to -55mV, and -55mV to -60mV at a pH of 10-11. It is understood that the zeta potentials of the aforementioned cerium oxide abrasive particles at a pH of 10-11 can be arbitrarily combined; for example, the cerium oxide abrasive particles may have a zeta potential of -20 to -45mV at a pH of 10-11.

[0036] Figure 1 A scanning electron microscope image of chamfered octahedral cerium oxide abrasive grains (purchased) provided according to an embodiment of this specification is shown; Figure 2A scanning electron microscope image of chamfered octahedral cerium oxide abrasive grains (prepared) according to an embodiment of this specification is shown.

[0037] like Figures 1-2 As shown, the cerium oxide abrasive grains in this solution can be chamfered octahedral cerium oxide abrasive grains. The term "chamfered octahedron" in this application refers to a polyhedron, specifically a polyhedron with 8 hexagonal faces and 6 square faces. Within the scope of this application, "chamfered octahedral cerium oxide" is not limited to an ideal chamfered octahedral morphology, but also includes octahedrons whose morphology changes due to manufacturing processes or other factors. For example, chamfered octahedral cerium oxide abrasive grains may have more or fewer than 8 hexagonal faces, and / or more or fewer than 6 square faces. The hexagonal or square faces may exhibit shape deviations (such as imperfect symmetry, irregular side lengths, or slight curvature). In some embodiments, the surface of the chamfered octahedral cerium oxide abrasive grains may exhibit a certain degree of unevenness or deformation. Studies have found that the chamfered octahedral morphology can improve the surface morphology of the polished single-crystal silicon substrate while still exhibiting a high removal rate of the single-crystal silicon substrate.

[0038] It should be noted that the chamfered octahedral cerium oxide abrasive grains may contain impurities. These impurities originate from the raw materials or processes used to prepare the abrasive grains and can be considered as not being part of the abrasive grain mixture; that is, these impurities are not added to the composition as a single component. This means that the impurities are not added in actual mass. The actual mass of the present invention is less than 30 ppm, further less than 20 ppm, further less than 10 ppm, and further less than 1 ppm. Here, ppm refers to weight ppm. It should be noted that the chamfered octahedral cerium oxide abrasive grains in this composition are preferably chamfered octahedral cerium oxide abrasive grains without impurities. For ease of illustration, the following description will use 100 wt% chamfered octahedral cerium oxide abrasive grains without impurities. It is understood that ppm refers to parts per million (ppm) of mass; for example, 20 ppm means "twenty parts per million".

[0039] Chamfered octahedral cerium oxide abrasive grains can be sol-gel cerium oxide abrasive grains, i.e., cerium oxide abrasive grains prepared by hydrolysis or sol-gel methods. Sol-gel cerium oxide abrasive grains can be obtained through wet processes, such as precipitation (e.g., precipitation synthesis of cerium oxide), hydrolysis-condensation reactions, or hydrothermal methods. In some embodiments, chamfered octahedral cerium oxide abrasive grains can be calcined chamfered octahedral cerium oxide abrasive grains. Calcined chamfered octahedral cerium oxide abrasive grains (post-calcined colloidalceria) refer to cerium oxide particles obtained after calcination treatment of the aforementioned colloidal chamfered octahedral cerium oxide abrasive grains; that is, cerium oxide particles that are first prepared as chamfered octahedral cerium oxide abrasive grains and then calcined at high temperatures to change their crystallinity, surface chemical properties, particle morphology, or other physicochemical properties. Calcined chamfered octahedral cerium oxide abrasive grains, due to high-temperature treatment, possess higher hardness and crystallinity, further improving removal efficiency, enhancing stability and durability during the grinding process, and improving the smoothness of the final surface.

[0040] Chamfered octahedral cerium oxide abrasive grains can have any range of particle size distribution. For example, the average particle size of chamfered octahedral cerium oxide abrasive grains, as measured by scanning electron microscopy, is 10 nm–200 nm. In some embodiments, the average particle size of chamfered octahedral cerium oxide abrasive grains, as measured by scanning electron microscopy, is 20 nm–100 nm. Furthermore, the average particle size of the chamfered octahedral cerium oxide abrasive particles, measured by scanning electron microscopy, is 10nm-20nm, 20nm-30nm, 30nm-40nm, 40nm-50nm, 50nm-60nm, 60nm-70nm, 70nm-80nm, 80nm-90nm, 80nm-90nm, 90nm-100nm, 100nm-110nm, 110nm-120nm, 120nm-130nm, 130nm-140nm, 140nm-150nm, 150nm-160nm, 160nm-170nm, 170nm-180nm, 180nm-190nm, and 190nm-200nm. The average particle size refers to the arithmetic mean of the maximum distance between two points on the particle boundary.

[0041] The particle size distribution of chamfered octahedral cerium oxide abrasive grains can have any characteristics, such as a wide or narrow particle size distribution. Furthermore, the particle size distribution can be polydisperse, monodisperse, or have multiple peaks, etc.

[0042] See Figure 1In some embodiments, the chamfered octahedral cerium oxide abrasive grains can be commercially available chamfered octahedral cerium oxide abrasive grains. These commercially available abrasive grains exhibit monodisperse distribution characteristics, meaning they have uniform particle size and a narrow distribution range, which is beneficial for achieving more uniform contact and force distribution during the grinding process. Due to their regular geometric structure and high surface smoothness, these abrasive grains improve grinding efficiency while effectively reducing surface defects, making them suitable for precision polishing processes with high surface quality requirements.

[0043] See Figure 2 In some embodiments, the chamfered octahedral cerium oxide abrasive particles can be self-prepared chamfered octahedral cerium oxide abrasive particles. In this application, the chamfered octahedral cerium oxide abrasive particles (i.e., dispersed cerium oxide nanoparticles prepared directly by sol-gel method, hydrolysis method, precipitation method, or similar wet process) are used. It can be seen that the chamfered octahedral cerium oxide abrasive particles exhibit polydispersity. These particles possess high surface activity and good dispersibility, providing a fine and uniform polishing effect and reducing surface defects.

[0044] 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 cerium oxide 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.

[0045] The composition also includes one or more polishing aids. The polishing aids are dissolved in a liquid carrier. The polishing aids can interact with abrasive particles and / or with the substrate and / or with the polishing pad during CMP processing. This interaction can be based on, for example, hydrogen bonds, van der Waals forces, electrostatic forces, etc. The polishing aids can be any component suitable for use as, for example, a removal rate promoter, a polishing rate inhibitor, a surfactant, a thickener, a modifier, a complexing agent, a chelating agent, a biocide, a dispersant, an oxidizing agent, a film-forming agent, an etching inhibitor, a catalyst, a terminating compound, a dissolution inhibitor, or a combination thereof.

[0046] Polishing aids include oxidants. While oxidants are generally avoided in traditional silica-based abrasive slurries during the chemical mechanical polishing of monocrystalline silicon (as they disrupt the stability of silica, leading to particle agglomeration and sedimentation, affecting slurry shelf life and polishing uniformity), they play a crucial role in systems using cerium oxide abrasives. Specifically, oxidants can rapidly oxidize the monocrystalline silicon surface in situ to silica. Cerium oxide particles have an extremely high chemical affinity for silica, efficiently removing the surface oxide layer through a synergistic effect of strong chemisorption and mechanical shearing. This "oxidation-adsorption-removal" cycle significantly improves material removal efficiency. Simultaneously, because cerium oxide abrasives have a lower affinity for unoxidized monocrystalline silicon, excessive erosion and surface defects are reduced, achieving a balance between high efficiency and high surface quality.

[0047] Oxidizing agents include both inorganic and organic compounds. Inorganic compounds include, but are not limited to, hydrogen peroxide, monopersulfate, diporsulfate, perchlorate, periodate, perborate, perbromate, peroxycarbonate, urea peroxide, disperoxydicarbonate, peroxymonosulfate, peroxydisulfate, perbromic acid, periodic acid, and perchloric acid. Organic compounds include, but are not limited to, benzyl peroxide, peracetic acid, dibutyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, methyl ethyl ketone peroxide, acetyl peroxide, lauryl peroxide, ethylbenzene peroxide, and cyclohexanone peroxide. In this scheme, inorganic compounds are preferred. Among the many inorganic compounds, hydrogen peroxide is preferred.

[0048] When used, the oxidant accounts for 0.01 wt.% to 5.0 wt.% of the composition by weight. In some embodiments, the oxidant accounts for 0.08 wt.% to 2.0 wt.% of the composition by weight. Further, the oxidant 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 oxidant weight percentages in the composition can be arbitrarily combined, for example, the oxidant weight percentage in the composition can be 1.0 wt.% to 2.0 wt.%.

[0049] Polishing aids also include catalysts. In the chemical mechanical polishing (CMP) process of single-crystal silicon, taking hydrogen peroxide as the oxidant as an example, the catalyst's role is to promote the decomposition of hydrogen peroxide (H₂O₂), efficiently generating highly reactive hydroxyl radicals (·OH), thereby accelerating the oxidation reaction on the single-crystal silicon surface, forming a silicon dioxide layer that is easily removed mechanically, and improving the material removal rate. However, iron-containing compounds (such as ferric nitrate) and other metal salts cannot be used as catalysts in the polishing of single-crystal silicon because Fe... 3 Metal ions, such as hydrogen peroxide, readily adsorb or remain on the silicon surface, introducing deep-level impurities. This leads to serious defects such as increased carrier recombination centers, increased leakage current, and decreased device reliability, severely impacting semiconductor device performance and yield. It is understood that the above description uses hydrogen peroxide as an example as the oxidant; other oxidants follow the same principle and will not be elaborated upon here.

[0050] Therefore, to avoid the aforementioned problems, a non-metallic catalyst is used in this scheme. Among numerous non-metallic catalysts, a nitrogen-based non-metallic catalyst is preferred in this scheme. Specifically, the nitrogen-based non-metallic catalyst includes at least one of hydroxylamine, hydroxylamine sulfate, hydroxylamine hydrochloride, hydrazine, hydrazine hydrate, phenylhydrazine, N,N-dimethylamine, triethylamine oxide, sodium azide, or phenyl azide and its derivatives.

[0051] Among numerous nitrogen-based nonmetallic catalysts, this scheme preferentially selects hydroxylamine as the catalyst. The following explanation uses hydroxylamine as an example. As a nonmetallic catalyst, hydroxylamine can activate H2O2 through a two-step reaction mechanism: First, protonated hydroxylamine reacts with H2O2 to generate ·OH and amino radicals (·NH2). Subsequently, the amino radicals further react with H2O2 to produce more ·OH and generate nitro groups (HNO), achieving a chain proliferation of free radicals, significantly enhancing oxidation capacity, and requiring no metal ions or external energy input.

[0052] When used, the catalyst accounts for 0.01 wt.% to 7.0 wt.% of the composition by weight. In some embodiments, the catalyst accounts for 0.1 wt.% to 5 wt.% of the composition by weight. In some embodiments, the catalyst accounts for 0.5 wt.% to 3 wt.% of the composition by weight. Further, the catalyst constitutes a portion of the composition by weight of 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 catalyst weight percentages in the composition can be arbitrarily combined, for example, the catalyst weight percentage in the composition can be 1.0 wt.% to 2.0 wt.%.

[0053] The polishing aid also includes a wetting agent. The wetting agent reduces the interfacial tension between the composition and the monocrystalline silicon surface, improving the spreadability and penetration of the composition on the monocrystalline silicon surface. This ensures that abrasive particles, oxidants, and catalysts are uniformly distributed on the monocrystalline silicon surface during polishing, preventing uneven local reactions and thus improving polishing uniformity. Among various wetting agents, this solution does not include polymeric wetting agents. Specifically, the oxidant in this solution is a non-metallic oxidant, represented by hydrogen peroxide. Taking hydrogen peroxide as an example, in the presence of hydrogen peroxide, polymers may undergo oxidative degradation, cross-linking, or free radical chain reactions, leading to molecular chain breakage or gelation. This not only results in the loss of wetting function but may also generate particulate contamination or consume the oxidant. The polymers mentioned here include hydroxymethyl cellulose, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), hydroxyethyl methyl cellulose (HEMC), ethyl hydroxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, methyl cellulose, ethyl cellulose, propyl cellulose, cellulose acetate, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), vinyl polymers of polyacrylamide and their derivatives, or combinations thereof. In other words, the wetting agent is not one of the polymers mentioned above. It should be noted that not only is the wetting agent not one of the polymers mentioned above, but the numerous chemical additives added to this composition also do not include one of the polymers mentioned above. That is to say, this composition does not contain one of the polymers mentioned above.

[0054] Therefore, polyols are chosen as the wetting agent in this solution. Polyols have a stable structure, do not contain easily oxidized sensitive functional groups, have strong antioxidant capacity, and can exist stably for a long time in an oxidizing environment composed of hydrogen peroxide (H2O2) and hydroxylamine, avoiding the introduction of instability or side reactions, thereby ensuring the overall performance and storage stability of the polishing solution.

[0055] Polyols include at least one of glycerol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol (1,3-butanediol or 1,4-butanediol), hexanediol (2-methyl-2,4-pentanediol), trimethylolpropane, neopentyl glycol, pentaerythritol, sorbitol, mannitol, xylitol, or erythritol.

[0056] When used, the wetting agent accounts for 0.01 wt.% to 7.0 wt.% of the composition by weight. In some embodiments, the wetting agent accounts for 0.1 wt.% to 5 wt.% of the composition by weight. In some embodiments, the wetting agent accounts for 0.5 wt.% to 3 wt.% of the composition by weight. Further, the wetting agent constitutes a portion of the composition by weight of 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 wetting agent weight percentages in the composition can be arbitrarily combined, for example, the wetting agent weight percentage in the composition can be 1.0 wt.% to 2.0 wt.%.

[0057] The polishing aid also includes a chelating agent. This chelating agent effectively complexes metal ions generated by oxidation reactions in the composition during the CMP process, preventing metal ions from depositing on the polishing interface or abrasive surface and passivating the reactivity. This maintains and enhances the continuity of the polishing process, helping to improve the material removal rate of the substrate surface, while also improving polishing uniformity and surface quality. The chelating agents include dicarboxylic acids, polycarboxylic acids, amino acids, aminocarboxylic acids, aminopolycarboxylic acids, phosphates, polyphosphates, aminophosphonic acids, phosphonocarboxylic acids, and combinations thereof.

[0058] 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.

[0059] 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).

[0060] 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 0.01 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.

[0061] Polishing aids also include surfactants. On one hand, surfactants help enhance the dispersion stability of cerium oxide abrasive particles in the composition, preventing particle agglomeration and thus maintaining consistent polishing performance. On the other hand, surfactants can also improve the wettability between the polishing pad and the substrate surface by adjusting interfacial tension, enhancing the uniform wetting effect of the polishing area. Furthermore, surfactants can effectively reduce microbubbles and residues generated during polishing, control the formation of optical defects (such as watermarks and spots), and reduce the roughness and haze of the substrate surface, significantly improving the cleanliness and optical quality of the polished surface.

[0062] The surfactant includes at least one of anionic or nonionic surfactants. In this embodiment, a nonionic surfactant is preferred. In some embodiments, the surfactant includes at least one of sodium dodecyl sulfate (SDS), sodium lauryl sulfate (SLS), sodium lauryl ether sulfate (SLES), sodium octyl sulfate, sodium decyl sulfate, disodium octyl sulfosuccinate (AOT / DOSS), potassium dodecyl sulfate, or ammonium lauryl sulfate. In some embodiments, the surfactant includes at least one of polyethylene glycol (PEG), polypropylene glycol, poly(ethylene oxide)-b-poly(propylene oxide), polyoxyethylene-polyoxyethylene alkylamine, poly((ethylene oxide)-b-(propylene oxide)-b(ethylene oxide)) triblock copolymer, polyoxyethylene-polyoxypropylene copolymer, and polyoxyethylene alkyl ether (PEOLE-polyoxyethylene dodecyl ether or PEOHE-polyoxyethylene hexyl ether). In some embodiments, the surfactant includes polyethylene glycol, polypropylene glycol, polyglycerol, polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxybutylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene fatty acid ester, polyoxyethylene glycerol ether fatty acid ester, polyoxyethylene dehydrated sorbitan fatty acid ester, polyoxyethylene polyoxypropylene copolymer, poly(ethylene oxide)-b-poly(propylene oxide), polyoxyethylene glycol, polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene dodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, and polyoxyethylene alkenyl ether. Polyoxyethylene dioxyethylene phenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene stearamide, polyoxyethylene oleamide, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene sorbitan monolaurate Esters, polyoxyethylene sorbitol monopalmitate, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol monooleate, polyoxyethylene sorbitol trioleate, polyoxyethylene sorbitol tetraoleate, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, acetylene glycol, polyoxyethylene-polyoxyethylene alkylamine, poly((ethylene oxide)-b-(propylene oxide)-b(ethylene oxide)) triblock copolymer or combinations thereof.

[0063] When used, the surfactant accounts for 0.001 wt.% to 2.0 wt.% of the composition by weight. In some embodiments, the surfactant accounts for 0.005 wt.% to 0.5 wt.% of the composition by weight. Further, the surfactant accounts for 0.001 wt.% to 0.005 wt.%, 0.005 wt.% to 0.01 wt.%, 0.01 wt.% to 0.05 wt.%, 0.05 wt.% to 0.1 wt.%, 0.1 wt.% to 0.5 wt.%, 0.5 wt.% to 0.8 wt.%, 0.8 wt.% to 1 wt.%, 1 wt.% to 1.5 wt.%, and 1.5 wt.% to 2 wt.%. 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.

[0064] The polishing aid also includes a coating agent. This coating agent can reversibly bind to the surface of cerium oxide abrasive grains through hydrogen bonding and / or ionic interactions, thereby effectively controlling the dispersion stability of the cerium oxide abrasive grains and inhibiting their agglomeration during storage or use. The coating agent can be in a free state or bound to the abrasive grains in the composition, preferably in a coated form. The coating agent can be dissolved in an aqueous carrier such as deionized water, then added to the cerium oxide abrasive grains and stirred thoroughly to allow the coating agent to be uniformly adsorbed onto the surface of the cerium oxide abrasive grains, forming a stable coating structure. This mixture is then introduced into the polishing composition to improve overall performance.

[0065] The coating agent is an anionic polymer. The anionic polymer can be used in any feasible form, such as an acid, conjugate acid, conjugate base, salt (e.g., ammonium salt), or combinations thereof. The anionic polymer contains repeating monomer units. The monomer units contain functional groups selected from carboxylic acids, sulfonic acids, sulfates, phosphonic acids, phosphoric acids, and combinations thereof. In a preferred embodiment, the repeating monomer units contain carboxylic acid functional groups.

[0066] Further, the carboxylic acids of the repeating monomer units include maleic acid, acrylic acid, aspartic acid, methacrylic acid, succinic acid, terephthalic acid, itaconic acid, and combinations thereof. The sulfonic acids of the repeating monomer units include vinyl sulfonic acid, styrene sulfonic acid, vinylbenzene sulfonic acid, ethyl methacrylate, propylene sulfonic acid, 3-sulfopropyl acrylate, propyl methacrylate, propyl sulfonate, acrylamide methylpropanesulfonic acid (AMPS), ethyl acrylate sulfonate, sodium styrene sulfonate, and combinations thereof. The phosphonic acids of the repeating monomer units include ammonium diethylphosphonate methacrylate, vinyl phosphonic acid, vinylbenzyl dimethylphosphonic acid, acrylamide phosphonic acid, vinylidene diphosphonic acid, and combinations thereof.

[0067] Anionic polymers can be homopolymers, copolymers, or combinations thereof. Anionic homopolymers include polysulfonic acid, poly(acrylamidomethylpropanesulfonic acid), polystyrene sulfonic acid, poly(vinyl sulfonic acid), poly(aspartic acid), polyacrylic acid, polymethacrylic acid, phosphonic polyacrylic acid, poly(methacrylic acid), poly(maleic acid), poly(itaconic acid), poly(maleic anhydride), anionic polyacrylamide, poly(methacrylamide), poly(methyl vinyl ether-copolymer-maleic acid), poly(methacrylamidomethylpropanesulfonic acid), poly(vinyl phosphonic acid), poly(vinyl phosphoric acid), poly(acrylamidomethylpropanesulfonic acid), poly(methacryloyloxyethanesulfonic acid), poly(acrylamidomethylpropanesulfonic acid), and poly(methacryloyloxyethyl... Phosphoric acid), poly(methacrylamidopropyl sulfonic acid), carboxymethyl inulin, polynaphthalene sulfonic acid, polyhydroxypropyl acrylate, poly(octadecyl acrylate), poly(tert-butyl acrylate), poly(tetrahydrofurfuryl methacrylate), poly(ethyl acrylate), poly(isobornyl acrylate), poly(isobutyl acrylate), poly(isodecyl acrylate), poly(isodecyl methacrylate), poly(isooctyl acrylate), poly(lauryl acrylate), poly(propyl acrylate), poly(butyl acrylate), poly(decyl acrylate), poly(hexyl acrylate), poly(octyl acrylate), poly(octyl methacrylate), polyepoxysuccinic acid, phosphonomethylated chitosan, and combinations thereof.

[0068] The copolymers include poly(acrylic acid-conmaleic acid) copolymers, poly(styrene sulfonic acid-conmaleic acid), poly(acrylamide-coacrylic acid), poly(vinylphosphonic acid-coacrylic acid), poly(vinyl sulfate), acrylic acid-acrylamide-methylpropanesulfonic acid copolymers, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid (AA-AMPS) in different weight percentages as shown, and combinations thereof.

[0069] The coating agent should have a low molecular weight (MW). If the molecular weight of the coating agent is too high, it will cause aggregation and agglomeration of cerium oxide abrasive particles, resulting in defects such as scratches on the substrate surface, and leading to cerium oxide abrasive particle precipitation and a shortened shelf life. Preferably, the coating agent has a molecular weight (MW) of up to 50,000 g / mol, more preferably up to 30,000 g / mol, more preferably up to 20,000 g / mol, more preferably up to 15,000 g / mol, and most preferably up to 9,000 g / mol. Preferably, the coating agent has a molecular weight of at least 100 g / mol, more preferably at least 200 g / mol, more preferably at least 300 g / mol, more preferably at least 400 g / mol, and most preferably at least 500 g / mol. In a preferred embodiment, the coating agent has a molecular weight of 100 g / mol to 50,000 g / mol, more preferably 200 g / mol to 30,000 g / mol, more preferably 300 g / mol to 20,000 g / mol, more preferably 400 g / mol to 15,000 g / mol, and more preferably 500 g / mol to 9,000 g / mol. Studies have found that the molecular weight of the coating agent can improve the removal rate of the substrate material during CMP and extend the shelf life of the composition.

[0070] When used, the coating agent accounts for 0.01 wt.% to 5.0 wt.% of the composition by weight. In some embodiments, the coating agent accounts for 0.05 wt.% to 2.0 wt.% of the composition by weight. Further, the coating agent accounts for 0.01 wt.% to 0.05 wt.%, 0.05 wt.% to 0.1 wt.%, 0.1 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.% of the composition by weight. It is understood that the above-mentioned coating agent weight ratio range of the composition can be arbitrarily combined, for example, the coating agent weight ratio of the composition is 1.0 wt.% to 2.0 wt.%.

[0071] The polishing aid also includes a pH adjuster. This pH adjuster helps the composition achieve the appropriate pH.

[0072] pH adjusters include N,N-dimethyloctylamine, N,N,N',N'-tetramethyl-1,3-propanediamine, N,N,N',N'-tetramethyl-1,6-hexanediammonium, 1,7-diaminoheptane, and N,N,N',N'-tetrabutyl-1,6-hexanediammonium. The pH adjuster comprises at least one of tetramethyl-1,6-hexammonium, N,N,N',N',N'-pentamethyldiethylenetriamine, N-(2-ethylamino)-1,3-propanediamine, hexamethyl quaternary ammonium hydroxide, N,N'-dimethyl-1,6-hexanediamine, and hexanediol-1,6-bis(tri-n-butylammonium). In some embodiments, the pH adjuster comprises at least one of tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine), N,N,N',N',N',N'-pentamethyldiethylenetriamine, N-(2-ethylamino)-1,3-propanediamine, hexamethyl quaternary ammonium hydroxide, N,N'-dimethyl-1,6-hexanediamine, and hexanediol-1,6-bis(tri-n-butylammonium). Further pH adjuster is tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine).

[0073] When used, the pH adjuster accounts for 0.01 wt.% to 7.0 wt.% of the composition by weight. In some embodiments, the pH adjuster accounts for 0.1 wt.% to 4 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 constitutes a portion of the composition at a weight ratio of 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 weight ratio ranges of the pH adjuster can be arbitrarily combined, for example, the pH adjuster may constitute a portion of the composition at a weight ratio of 1.0 wt.% to 2.0 wt.%.

[0074] The pH value of the composition affects the removal rate of monocrystalline silicon substrate during CMP treatment. 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 8 to 11 when used. In some embodiments, the composition has a pH value of 10 to 11 when used. Further, the composition has a pH value between 8 and 10, and between 10 and 11 when used.

[0075] 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.

[0076] The composition can be prepared using suitable techniques known to those skilled in the art. As described above, cerium oxide abrasive particles and other components besides the cerium oxide abrasive particles can be added to the liquid carrier in any order and in suitable amounts to achieve the desired concentration. The cerium oxide abrasive particles and other components can be mixed and stirred in the liquid carrier. The pH value can be adjusted using the pH adjuster described above to obtain and maintain the desired pH. The cerium oxide abrasive particles and other components can be added at any time before use or during CMP treatment.

[0077] 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 cerium oxide 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.

[0078] 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.

[0079]

preparation

[0080] Preparation of chamfered octahedral cerium oxide abrasive grains:

[0081] like Figure 2The preparation process of the chamfered octahedral cerium oxide abrasive particles is as follows: 200g of cerium(III) nitrate hexahydrate (Ce(NO3)3·6H2O) was dissolved in 500mL of deionized water and stirred at room temperature until the solid dissolved, denoted as solution A. 100mL of ammonia water was dissolved in 400mL of deionized water and stirred until the solid dissolved, denoted as solution B. Solution B was slowly added to solution A while stirring at room temperature for 30min. The mixture was placed in a water bath at 85℃ for 4 hours. The cooled mixture was centrifuged to obtain a white solid, which was then acidified with water and acetic acid to obtain a suspension of chamfered octahedral cerium oxide. The chamfered octahedral cerium oxide abrasive particles were obtained. The average particle size of the chamfered octahedral cerium oxide abrasive particles was 42.25nm. The average particle size of the chamfered octahedral cerium oxide abrasive particles was measured using a NovaNano450 scanning electron microscope. The average particle size is obtained by taking the arithmetic mean of the maximum distances between two points on the particle boundary measured from 1000 particles.

[0082] Preparation of the composition:

[0083] The compositions of all embodiments were prepared by adding and dissolving a polishing aid in deionized water. Then, chamfered octahedral cerium oxide abrasive particles were added and stirred until the chamfered octahedral cerium oxide abrasive particles were dispersed.

[0084] [Polishing Process]

[0085] Using KIZI polishing equipment (Dongguan Jinyan Precision Grinding Machinery Manufacturing Co., Ltd.), a chemical mechanical polishing (CMP) process was performed on the surface of a 6-inch circular silicon wafer for 80 seconds under the following conditions: table speed 50 rpm, die head speed 50 rpm, downforce 1.4 psi, and polishing slurry flow rate 100 mL / min. After polishing, the wafer was rinsed with deionized water, and then cleaned for 20 minutes at 21°C with SC-1 cleaning solution (ammonia (29 wt.%): hydrogen peroxide (31 wt.%): deionized water = 1:3:30, volume ratio), and scrubbed with a PVA brush. Finally, the wafer surface was dried with high-purity nitrogen.

[0086]

Measurement

[0087] Removal Rate (RR) Measurement:

[0088] The mass change of silicon wafers before and after polishing was measured by weighing using a Mettler Toledo Instruments (Shanghai) Co., Ltd., and the material removal rate was calculated and determined.

[0089] Surface roughness (Ra) measurement:

[0090] Five measurement points (the center point and four symmetric points 20 mm from the edge) were selected on the surface of a silicon wafer using a Park Systems NX20 atomic force microscope (AFM) to measure the polished surface roughness (Ra). The surface roughness Ra is defined as the arithmetic mean of the absolute values of the deviations of the profile heights from the mean height.

[0091] Hydrophilicity measurement:

[0092] The hydrophilicity assessment starts with a score of 100 and uses a two-step scoring method.

[0093] First step: After polishing, the silicon wafer is placed horizontally and the state of the water film on the surface is observed; if the water film is intact, record the edge shrinkage distance a within 3 seconds (a = 0 no deduction; 0 < a ≤ 0.5 cm, deduct 10 points; 0.5 < a ≤ 2 cm, deduct 20 points; 2 < a ≤ 5 cm, deduct 30 points; a > 5 cm, deduct 50 points); if the water film is incomplete, measure the distance b from the edge to the nearest water film (b = 0 no deduction; 0 < b ≤ 0.5 cm, deduct 10 points; 0.5 < b ≤ 2 cm, deduct 20 points; b > 5 cm, deduct 50 points). When a ≤ 0.5 cm (water film intact) or b ≤ 0.5 cm (water film incomplete), proceed to the second step.

[0094] Second step: After rinsing for 10 seconds under a water pressure of 90 Pa and a flow rate of 2 L / min, place the wafer vertically and record the time t when the water film starts to slide (t ≤ 3 s, deduct 30 points; 3 < t ≤ 5 s, deduct 20 points; 5 < t ≤ 10 s, deduct 10 points; t > 10 s no deduction), and record the distance c between the upper edge and the top of the water film at 10 seconds after vertical placement (c < 1 cm, deduct 10 points; 1 ≤ c < 3 cm, deduct 20 points; 3 ≤ c < 5 cm, deduct 30 points; c ≥ 5 cm, deduct 50 points). The lower the final score, the worse the hydrophilicity. A score ≤ 50 points is determined as insufficient hydrophilicity, not meeting the process requirements.

[0095] Measurement of average particle size and zeta potential:

[0096] After preparing the composition, it is left to stand at room temperature for 36 hours without stirring. Subsequently, the average particle size and zeta potential of the particles in the composition are measured by dynamic light scattering using a Malvern Mastersizer S (Malvern Instruments Limited).

[0097] Example 1:

[0098] Compositions A1 - A2 and E1 contain 3 wt% of octahedral cerium oxide abrasive grains with chamfered corners (such as Figure 1As shown, the composition contains monodisperse truncated octahedral cerium oxide abrasive particles, 0.2 wt% coating agent, 0.03 wt% surfactant, and 0.05 wt% chelating agent. The pH was adjusted to 10.5 using a pH adjuster. The coating agent is polyacrylic acid. The surfactant is polyethylene glycol (PEG). The chelating agent is diethylenetriaminepentaacetic acid (DTPA). The pH adjuster is tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine). In addition to these common components, these compositions also contain different oxidizing agents and wetting agents, as detailed in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] in conclusion:

[0103] (1) Compared with composition A1, composition A2 containing oxidant H2O2 has a higher removal rate and better hydrophilicity. At the same time, composition A2 has a lower surface roughness Ra, that is, better surface quality;

[0104] (2) Compared with composition A2, composition E1, which contains a polyol wetting agent, has a higher material removal rate. At the same time, composition E1 has less particle agglomeration and better zeta potential retention.

[0105] Example 2:

[0106] Composition E2-E7 contains 3 wt% chamfered octahedral cerium oxide abrasive grains (e.g. Figure 2 As shown, the prepared polydisperse truncated octahedral cerium oxide abrasive particles contain 0.2 wt% coating agent, 0.01 wt% surfactant, and 0.05 wt% chelating agent. The pH is adjusted to 10.5 using a pH adjuster. The truncated octahedral cerium oxide abrasive particles are prepared according to the steps described above. The coating agent is polystyrene sulfonic acid. The surfactant is polyoxyethylene isodecanyl ether. The chelating agent is ethylenediaminetetramethylenephosphonic acid (EDTMPA). The pH adjuster is tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine). In addition to these common components, these compositions also contain different oxidants, catalysts, and wetting agents, as detailed in Table 2.

[0107] Table 2

[0108]

[0109] in conclusion:

[0110] (1) Compared with compositions E2 and E5, compositions E3 and E6 containing hydroxylamine exhibited higher material removal rates (RR);

[0111] (2) Compared with other compositions, compositions E4 and E7, which contain both hydroxylamine and H2O2, exhibit higher material removal rate (RR) and lower surface roughness (Ra). In other words, compositions containing both hydroxylamine and H2O2 can improve surface quality while increasing material removal rate.

[0112] Example 3:

[0113] Compositions A3-A10 and E8-E11 contain 3 wt% truncated octahedral cerium oxide abrasive grains, 0.2 wt% coating agent, 0.01 wt% surfactant, 0.05 wt% chelating agent, and 2 wt% wetting agent. The pH is adjusted to 10.5 using a pH adjuster. The truncated octahedral cerium oxide abrasive grains are prepared according to the steps described above. The coating agent is polystyrene sulfonic acid. The surfactant is polyethylene glycol (PEG). The chelating agent is diethylenetriaminepentaacetic acid (DTPA). The wetting agent is glycerol. In addition to these common components, these compositions also contain different oxidants, catalysts, and pH adjusters, as shown in Table 3. It should be noted that: TMAH is tetramethylammonium hydroxide; HMH is hexamethylammonium hydroxide; and TMHMD is tetramethyl-1,6-hexammonium diamine.

[0114] Table 3

[0115]

[0116] in conclusion:

[0117] (1) Compared with compositions A3-A6, compositions E8-E11 exhibit better hydrophilicity and lower surface roughness;

[0118] (2) Compared with compositions A7-A10, compositions E8-E11 exhibited a lower average particle size and a higher zeta potential three days after composition preparation. In other words, compositions E8-E11 showed better stability and less particle agglomeration.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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 single-crystal silicon substrates, characterized in that, include: Cerium oxide abrasive particles; Oxidizing agent; as well as The catalyst is a nitrogen-based nonmetallic compound.

2. The composition according to claim 1, characterized in that, The composition does not contain silica abrasive particles.

3. The composition according to claim 1, characterized in that, The cerium oxide abrasive grains are chamfered octahedral cerium oxide abrasive grains.

4. The composition according to claim 1, characterized in that, The cerium oxide abrasive particles have a zeta potential of -12 mV to -60 mV when the pH of the composition is 10-11.

5. The composition according to claim 1, characterized in that, The nitrogen-based nonmetallic compounds include at least one of hydroxylamine, hydroxylamine sulfate, hydroxylamine hydrochloride, hydrazine, hydrazine hydrate, phenylhydrazine, N,N-dimethylamine, triethylamine oxide, sodium azide, or phenyl azide and their derivatives.

6. The composition according to claim 1, characterized in that, The nitrogen-based nonmetallic compound is hydroxylamine.

7. The composition according to claim 1, characterized in that, The oxidant is an inorganic non-metallic compound, which includes at least one of hydrogen peroxide, monopersulfate, diporsulfate, perchlorate, periodate, perborate, perbromate, peroxycarbonate, peroxyurea, diporoxydicarbonate, peroxymonosulfate, peroxydisulfate, perbromic acid, periodic acid, or perchloric acid.

8. The composition according to claim 1, characterized in that, The composition further includes a pH adjuster comprising at least one of tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine), N,N,N',N',N”-pentamethyldiethylenetriamine, N-(2-ethylamino)-1,3-propanediamine, hexamethyl quaternary ammonium hydroxide, N,N'-dimethyl-1,6-hexanediamine, and hexane-1,6-bis(tri-n-butylammonium) dihydrogen phosphate.

9. The composition according to claim 8, characterized in that, The pH adjuster is tetramethyl-1,6-hexanediamine (N,N,N',N'-tetramethyl-1,6-hexanediamine).

10. The composition according to claim 1, characterized in that, The composition further includes a wetting agent comprising a polyol and not containing a polymer.

11. The composition according to claim 10, characterized in that, The polyols include at least one of glycerol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol (1,3-butanediol or 1,4-butanediol), hexanediol (2-methyl-2,4-pentanediol), trimethylolpropane, neopentyl glycol, pentaerythritol, sorbitol, mannitol, xylitol, or erythritol.

12. The composition according to claim 1, characterized in that, The composition does not contain hydroxyethyl cellulose or polyvinylpyrrolidone.

13. A polishing method for single-crystal silicon substrates, characterized in that, The method utilizes the composition as described in any one of claims 1-12 to polish a single-crystal silicon substrate.

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