Polishing composition for silicon carbide surfaces and method of use thereof

Abstract

The present disclosure relates to a chemical mechanical polishing (CMP) composition for polishing polycrystalline silicon carbide-containing surfaces. More specifically, the polishing composition is in the form of a slurry having a pH of 8 or greater that includes an oxidizing agent and an abrasive.

Description

[Technical field]

[0001] The present disclosure relates to a chemical mechanical polishing (CMP) composition for polishing a polycrystalline silicon carbide-containing surface. More specifically, the polishing composition disclosed herein is in the form of a slurry having a pH of 8 or greater that includes an oxidizing agent and an abrasive. [Background technology]

[0002] Chemical mechanical polishing (CMP) is a process that removes material from the surface of a substrate (such as a semiconductor wafer) and polishes (planarizes) the surface by combining physical processes, such as polishing, with chemical processes, such as oxidation. In its most basic form, CMP involves applying a slurry to the surface of the substrate or a polishing pad that polishes the substrate. This process accomplishes both the removal of unwanted material and the planarization of the surface of the substrate. It is not desirable for the removal or polishing process to be purely physical or purely chemical, but rather to involve a synergistic combination of both.

[0003] CMP is used on a wide variety of substrates, including, for example, silicon dioxide (SiO2) in interlayer or buried dielectrics, metals such as aluminum (Al), copper (Cu), tungsten (W), and other barrier metal layers such as tantalum (Ta), tantalum nitride (TaN), and titanium (Ti) in interconnect layers or plugs connecting to such interconnect layers, and polycrystalline silicon carbide (poly-SiC) in semiconductor and other materials.

[0004] Typically, silicon substrates are used in the manufacture of semiconductors. However, due to the inherent properties of silicon, further development is limited. The development of next generation semiconductor devices has emphasized the use of materials with higher hardness and other unique properties. For example, silicon carbide has higher thermal conductivity, higher radiation resistance, higher dielectric strength, and can withstand higher temperatures compared to silicon oxide. However, the use of silicon carbide has been limited by semiconductor manufacturing technology.

[0005] To produce silicon carbide semiconductors, the surface of the silicon carbide substrate must be polished to provide a smooth surface and precise surface dimensions. To date, the adaptation of CMP technology for silicon carbide polishing has not been very successful. Polishing compositions containing colloidal silica have a slow removal rate of silicon carbide, and therefore require long polishing cycles of several hours at temperatures around 50°C, which is likely to damage the silicon carbide substrate. See, for example, Zhou et al., J. Electrochemical Soc., Vol. 144, pp. L161-L163 (1997); Neslen et al., J. Electronic Materials, Vol. 30, pp. 1271-1275 (2001). The long polishing cycles add significant costs to the process and are a barrier to the widespread use of silicon carbide in the semiconductor industry.

[0006] Silicon carbide used in semiconductors can be single crystal or polycrystalline. Silicon carbide has many different types of crystal structures, each with its own distinct set of electronic properties. However, only a few of these polymorphs can be reproduced in forms acceptable for use as semiconductors. Such polymorphs can be either cubic (e.g., 3C silicon carbide) or non-cubic (e.g., 4H silicon carbide, 6H silicon carbide), or a mixture of polymorphs (i.e., polycrystalline).

[0007] In addition to the differences between the crystal polymorphs, there are significant differences between the single crystal form and polycrystalline silicon carbide. For example, the use of single crystal silicon carbide substrates in the manufacture of semiconductors increases the manufacturing costs of single crystal silicon carbide substrates. Also, when the substrate is subjected to heat treatment or the like, crystal slip dislocations may occur, causing deformation of the substrate.

[0008] Compared with the use of single crystal SiC substrates, poly-SiC substrates can be manufactured relatively inexpensively. To construct a SiC power semiconductor device, it is necessary to form a drift layer on a single crystal SiC substrate by epitaxy, and then form gates, electrodes, etc. on the drift layer. The process cost of using only expensive single crystal substrates is one of the major problems that limit the widespread use of single crystal SiC-containing devices. The use of poly-SiC reduces the process cost because i) only a few microns of the surface layer of the single crystal SiC substrate are used as the bulk epitaxial junction layer of the SiC power semiconductor, and ii) poly-SiC is used as the support substrate for the stacked substrate (see https: / / www.chusho.meti.go.jp / keiei / sapoin / portal / seika / 2015 / 2720403030h.pdf).

[0009] Poly-SiC substrates also contain numerous grain boundaries that block dislocation slippage and limit deformation of the substrate after heat treatment. For at least these reasons, poly-SiC is becoming more popular in semiconductor manufacturing.

[0010] However, when chemical mechanical polishing (CMP) is applied to the surface of a poly-SiC-containing substrate to obtain a smooth surface, low removal rates and poor surface smoothness often result. This is because poly-SiC substrates have different polar planes and crystal orientation planes that are exposed on the substrate surface, and each plane or surface has a different polishing removal rate. Simply put, poly-SiC consists of different crystal plane domains or crystal polymorphs, so different removal rates are observed during the CMP process, making it difficult to achieve both a high removal rate and a smooth surface.

[0011] In light of the challenges surrounding polishing poly-SiC-containing substrates, it is important to identify polishing compositions that enable high poly-SiC removal rates while simultaneously enabling low average roughness. These and other challenges are addressed by the subject matter disclosed herein. [Prior art documents] [Non-patent literature]

[0012] [Non-Patent Document 1] Zhou et al., J. Electrochemical Soc., vol. 144, pp. L161-L163 (1997) [Non-Patent Document 2] Neslen et al., J. Electronic Materials, vol. 30, pp. 1271-1275 (2001) [Non-Patent Document 3] https: / / www.chusho.meti.go.jp / keiei / sapoin / portal / seika / 2015 / 2720403030h.pdf Summary of the Invention [Problem to be solved by the invention]

[0013] In accordance with the objectives of the presently disclosed subject matter or problem solved by the present invention, as embodied and broadly described herein, it is an object of the present invention to provide compositions for polishing substrates, such as substrates containing polycrystalline silicon carbide (poly-SiC), that impart a desirable surface morphology (i.e., surface roughness) to the substrate when using CMP. Another object of the present invention is to provide an efficient method for polishing such poly-SiC-containing substrates using the polishing compositions disclosed herein. [Means for solving the problem]

[0014] Thus, the subject matter of the present disclosure in one aspect relates to a polishing composition comprising an oxidizing agent and an abrasive, the polishing composition having a pH of 8 or greater. In some embodiments, the oxidizing agent is a complex metal oxide (e.g., potassium permanganate) and the abrasive is alumina. In some embodiments, the amount of oxidizing agent present in the polishing composition ranges from about 1.5% to about 3.5% (by weight) and the amount of abrasive ranges from about 1.5% to about 3.5% (by weight).

[0015] In another aspect, the subject matter described herein relates to a method for polishing a substrate, comprising: 1) providing a polishing composition described herein; 2) providing a substrate comprising a polycrystalline silicon carbide layer; and 3) polishing the substrate with the polishing composition to obtain a polished substrate. In some embodiments, the polishing method has a high removal rate (RR). In some embodiments, the polishing method produces a substrate with a low roughness index (Ra).

[0016] These and other aspects are disclosed in further detail below. [Brief description of the drawings]

[0017] [Figure 1] 1 is a graph showing surface morphology Ra / Rz as a function of pH for test wafer 1. [Diagram 2] 1 is a graph showing removal rate and surface morphology Ra as a function of potassium permanganate (KMnO4) concentration, the graph being for test wafer 1. [Diagram 3] 1 is a graph showing removal rate and surface morphology Ra as a function of alumina powder concentration, the graph being for test wafer 1. [Figure 4] 1 is a graph showing surface morphology Ra / Rz as a function of pH for test wafer 2. [Diagram 5] 1 is a graph showing removal rate and surface morphology Ra as a function of potassium permanganate (KMnO4) concentration, the graph being for test wafer 2. [Figure 6] 1 is a graph showing removal rate and surface morphology Ra as a function of alumina powder concentration, the graph being for test wafer 2. [Figure 7] 2 is a graph showing the relationship between the pH of the polishing composition and the oxidation-reduction potential ORP. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention may be understood more readily by reference to the following detailed description of the invention and the examples included therein.

[0019] Before the present compounds, compositions, articles, systems, devices, and / or methods are disclosed and described, it should be understood that they are not limited to specific synthesis methods unless otherwise specified, or to specific components unless otherwise specified, and therefore can, of course, vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, exemplary methods and materials are described herein.

[0020] As described herein, in an embodiment, the polishing composition includes an oxidizing agent and an abrasive, and the pH of the composition is 8 or more. These polishing compositions are for polishing poly-SiC-containing substrates. The polishing compositions exhibit at least one of the following advantages: 1) high removal rate, 2) smooth surface with low Ra, 3) high efficiency and planarization ability, 4) CMP process without the need to use fine lapping and / or grinding process, and 5) lower manufacturing cost.

[0021] The polishing compositions described herein have uses such as, but are not limited to, chemical-mechanical polishing of poly-SiC-containing semiconductor wafers.

[0022] A.Definition Listed below are definitions of various terms used to describe this invention. These definitions apply to the terms as they are used throughout this specification, unless otherwise limited in specific instances, either individually or as part of a larger group.

[0023] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an abrasive" or "pH adjuster" includes a mixture of two or more such abrasives or pH adjusters.

[0024] Ranges can be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another aspect includes the one particular value and / or the other particular value. Similarly, when values ​​are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each range are significant in relation to the other endpoint, as well as independently of the other endpoint. It will also be understood that there are several values ​​disclosed herein, and that each value is also disclosed herein as "about" that particular value in addition to the value itself. For example, when the value "10" is disclosed, "about 10" is also disclosed. Also, for example, when the value "about 10" is disclosed, "10" is also disclosed. It is also understood that each unit between two particular units is also disclosed. For example, when 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed. As used herein, when there is a statement of about X (X being a numerical value), about X is X±10%.

[0025] Weight percentages (wt %) of components are based on the total weight of the vehicle or composition in which the component is included, unless otherwise specified.

[0026] As used herein, the terms "optional" and "optionally" mean that the subsequently described event or circumstance may or may not occur, and that the description includes cases where said event or circumstance occurs and cases where said event or circumstance does not occur.

[0027] As used herein, the term "removal rate" (RR) refers to the amount of material removed per time, e.g., μm per hour (μm / hr). The more material removed per hour, the higher the material removal rate. More specifically, the RR can be calculated using the weight loss and crystal density before and after CMP.

[0028] As used herein, the term "roughness index" (Ra) is a calculated value that characterizes the degree of roughness of a surface, i.e., the texture of a surface that is irregular and non-uniform rather than smooth. The lower the value, the smoother the surface.

[0029] As used herein, the term "specific average roughness depth" (Rz) is the average value calculated from all heights and depths present on a surface, thereby further characterizing the texture of the surface.

[0030] Ra and Rz can be calculated according to JIS B 0601-2001 or ISO 13565-1: 1996. The roughness curve on which Ra and Rz are based can be measured by the device (atomic force microscope (AFM)) used in the examples described later.

[0031] B. Polishing composition The basic mechanism of chemical mechanical polishing (CMP) is to soften the surface layer by chemical reaction, and then remove the softened layer by mechanical force by abrasive particles. However, the role of CMP is not only material removal, but also planarization, surface smoothing, uniformity control, defect reduction, etc. Therefore, semiconductor yield improvement is affected by CMP processing. Surface scratches that can be caused by CMP are extremely harmful defects in semiconductor manufacturing. Therefore, the development of polishing compositions is very important to achieve suitable CMP performance without scratching the surface. The requirements of CMP may include a planarized surface of less than 13 nm, a roughness-free surface with a surface roughness of less than 1.2 nm, and a defect-free surface with a scratch and pit count of 0 counts per wafer. In some embodiments, the planarization is free of contamination, has high productivity, and is achieved with a high removal rate of the desired removed material. Here, the planarized surface can be evaluated by the index of Rz, and the roughness-free surface can be evaluated by the index of Ra.

[0032] CMP is often used as part of a polishing process to polish poly-SiC-containing surfaces. Due to its high level of hardness and remarkable chemical inertness, polishing of poly-SiC-containing surfaces can be difficult. Typically, to prepare poly-SiC wafers, multiple polishing steps must be performed that require particles even harder than poly-SiC itself to achieve reasonable polishing rates. However, using such hard particles often results in high levels of damage to the surface, such as scratches and dislocations, that typically occur both at the surface and below the surface of the wafer. Therefore, a CMP slurry and / or a method of polishing poly-SiC that can reduce damage and increase the polishing rate of poly-SiC-containing materials is highly desirable.

[0033] In this regard, therefore, the present disclosure relates to polishing compositions having a pH of 8 or more, comprising a composite metal oxide as an oxidizing agent and alumina as an abrasive. These polishing compositions have been found to provide high polishing rates and desirable surface morphology, and show reduced damage compared to that typically observed in conventional polishing methods. These polishing compositions and methods of using them are disclosed in more detail below.

[0034] 1. Oxidizing Agent The polishing composition disclosed herein contains an oxidizing agent, which undergoes an oxidation reaction with the surface of the object to be polished and can aid in the polishing process of various surfaces.

[0035] In some embodiments, the oxidizing agent present in the polishing composition can be, for example, permanganic acid and its salts, such as permanganate and its salts, including sodium permanganate and potassium permanganate; peroxides, such as hydrogen peroxide; nitric acid and its salts, such as iron nitrate, silver nitrate, aluminum nitrate, and its complexes, including cerium ammonium nitrate; persulfate compounds, such as persulfates, including peroxomonosulfuric acid, peroxodisulfuric acid, and the like, and their salts, including ammonium persulfate, potassium persulfate, and the like; chlorine-containing compounds, such as chloric acid and its salts, perchloric acid and its salts, including potassium perchlorate; bromine-containing compounds, such as bromic acid and its salts, including potassium bromate; iodic acid, its salts, including ammonium iodate, periodate, Examples of the acid include iodine-containing compounds such as periodate and its salts, such as sodium periodate and potassium periodate; ferric acids such as ferric acid and its salts, such as potassium ferric acid; chromic acids such as potassium chromate and its salts, such as potassium dichromate; vanadic acids such as ammonium vanadate, sodium vanadate, and potassium vanadate; ruthenic acids, such as perruthenic acid and its salts; molybdic acids such as ammonium molybdate and its salts, such as disodium molybdate; rhenic acids, such as perrhenic acid and its salts; and tungstic acids such as tungstic acid and its salts, such as disodium tungstate. These may be used alone or in combination of two or more.

[0036] In some embodiments, the oxidizing agent present in the polishing composition comprises complex metal oxide.Examples of complex metal oxide include, but are not limited to, nitrate, ferric acid, permanganic acid, chromic acid, vanadic acid, ruthenic acid, molybdic acid, rhenic acid, and tungstic acid.Among these, ferric acid, permanganic acid, and chromic acid are more preferred, and permanganic acid is even more preferred.

[0037] In some embodiments, the composite metal oxide contains a monovalent or divalent metal element other than a transition metal element, and a transition metal element in the fourth period of the periodic table is used as the composite metal oxide. As the monovalent or divalent metal element, Na, K, Mg, Ca, etc. are preferred. Among these, Na and K are more preferred. Preferred examples of the transition metal element in the fourth period of the periodic table include Fe, Mn, Cr, V, Ti, etc. Among these, Fe, Mn, and Cr are more preferred, and Mn is even more preferred. The composite metal oxide effectively reduces the hardness of the surface, which may cause embrittlement of the surface of a high-hardness material such as poly-SiC.

[0038] In some embodiments, the amount of oxidizing agent affects the properties of the polishing composition, such as RR, Ra, and Rz. The amount of oxidizing agent in the polishing composition is in the range of about 0.01 wt% to about 5.0 wt%, about 0.05 wt% to about 4.5 wt%, about 0.1 wt% to about 4.0 wt%, about 0.5 wt% to about 3.5 wt%, about 1.0 wt% to about 3.5 wt%, about 1.5 wt% to about 3.5 wt%, about 1.5 wt% to about 3.0 wt%, or about 2.0 wt% to about 3.0 wt%. Alternatively or additionally, the amount of oxidizing agent present in the polishing composition is less than about 5.0 wt%, less than about 4.5 wt%, less than about 4.0 wt%, less than about 3.5 wt%, less than about 3.0 wt%, less than about 2.5 wt%, less than about 2.0 wt%, less than about 1.5 wt%, or less than about 1 wt%. In some embodiments, the amount of oxidizing agent is about 1.5 wt%, about 2.0 wt%, about 2.5 wt%, about 2.95 wt%, about 3.0 wt%, or about 3.5 wt%. The percentage of oxidizing agent is measured relative to the total composition. In some embodiments, the amount of oxidizing agent may range from 1.5 wt% to 3.5 wt% in the polishing composition. In some embodiments, the amount of permanganate may range from 1.5 wt% to 3.5 wt% in the polishing composition.

[0039] In one embodiment, the polishing composition has an oxidation-reduction potential ORPx that is 100 mV or more higher than the oxidation-reduction potential ORPy of the object to be polished. In some embodiments, the polishing composition has an oxidation-reduction potential ORPx that is about 150 mV, 200 mV, 250 mV, 300 mV, 350 mV, 400 mV, 450 mV, 500 mV, 550 mV, or about 600 mV higher. In some embodiments, the polishing composition has an oxidation-reduction potential ORPx that is about 150 mV or more, 200 mV or more, 250 mV or more, 300 mV or more, 350 mV or more, 400 mV or more, 450 mV or more, 500 mV or more, 550 mV or more, or about 600 mV or more higher than the oxidation-reduction potential ORPy of the object to be polished. In one embodiment, the polishing composition has an oxidation-reduction potential ORPx in the range of about 100 mV to about 1500 mV, about 200 mV to about 1400 mV, about 300 mV to about 1300 mV, about 400 mV to about 1200 mV, about 400 mV to about 1100 mV, about 400 mV to about 1000 mV, about 400 mV to about 900 mV, about 400 mV to about 800 mV, about 450 mV to about 800 mV, about 500 mV to about 1200 mV, about 600 mV to about 1200 mV, about 700 mV to about 1200 mV, about 800 mV to about 1100 mV, or about 800 mV to about 1,000 mV. That is, the relationship between ORPx (mV) and ORPy (mV) satisfies the following formula (1): ORPx-ORPy≧100 mV (1). In one embodiment, the oxidation-reduction potential ORPx of the polishing composition may be about 800 mV or less, about 750 mV or less, about 650 mV or less, about 600 mV or less, or about 550 mV or less. In one embodiment, the oxidation-reduction potential ORPy of the polishing object may be about 460 mV at pH 8.0, about 400 mV at pH 9.0, about 330 mV at pH 10.0, about 300 mV at pH 11.0, about 220 mV at pH 12.0, about 190 mV at pH 13.0, and about 150 mV at pH 14.0.

[0040] The redox potential of the polishing composition and the polished object referred to here refers to the value of the redox potential relative to a standard hydrogen electrode measured at a liquid temperature of 25° C. The redox potential can be measured by using a Horiba Laqua Act PC110 as the main body of the measuring device and a Horiba Laqua 9300-10D as the electrode.

[0041] 2. Abrasive grain The polishing composition described herein contains an abrasive. The abrasive is typically a metal oxide abrasive, preferably selected from the group consisting of silica, alumina, titania, zirconia, germanium, ceria, and mixtures thereof. In some embodiments, the abrasive is alumina. In further embodiments, the abrasive contains alpha alumina.

[0042] The abrasive grains disclosed herein exhibit a suitable isoelectric point. For example, suitable isoelectric points are in the range of about 3 to about 8.5, about 3.5 to about 8.0, about 4 to about 7.5, about 4.5 to about 7.0, about 5 to about 7, or about 5.5 to about 6.5. In some embodiments, the abrasive grains exhibit an isoelectric point of less than about 9.0, less than about 8.5, less than about 8.0, less than about 7.5, less than about 7.0, less than about 6.5, less than about 6, or less than about 5. In some embodiments, the isoelectric point is about 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, or 8.0. The isoelectric point of the abrasive grains in the examples described below was about 5 to 7. In some embodiments, the isoelectric point can be calculated by measuring the zeta potential. The zeta potential [mV] may be calculated, for example, by subjecting the object to be measured for zeta potential to an ELS-Z2 manufactured by Otsuka Electronics Co., Ltd., measuring the object at a measurement temperature of 25°C using a flow cell by the laser Doppler method (electrophoretic light scattering measurement method), and analyzing the obtained data by the Smoluchowski formula.

[0043] The abrasive grains can have any suitable particle size. The abrasive grains can have an average secondary particle size of about 10 nm or more, about 25 nm or more, 50 nm or more, about 100 nm or more, or about 500 nm or more. In some embodiments, the abrasive grains can have an average secondary particle size of about 100 nm or more, about 200 nm or more, about 250 nm or more, about 300 nm or more, about 350 nm or more, or about 380 nm or more. Alternatively or additionally, the abrasive grains can have an average secondary particle size of about 1,000 nm or less, about 500 nm or less, about 200 nm or less, about 150 nm or less, about 100 nm or less, about 50 nm or less, or about 25 nm or less. In some embodiments, the abrasive grains can have an average secondary particle size of about 900 nm or less, about 800 nm or less, about 700 nm or less, about 650 nm or less, or about 600 nm or less. For example, in some embodiments, the abrasive grains can have an average secondary particle size in the range of about 10 nm to about 500 nm, about 20 nm to about 100 nm, or about 30 nm to about 50 nm. For example, in some embodiments, the abrasive grains can have an average secondary particle size in the range of about 100 nm to about 500 nm, about 200 nm to about 500 nm, or about 300 nm to about 500 nm. In some embodiments, the average secondary particle size is about 10 nm, about 15 nm, about 20 nm, about 25 nm, about 30 nm, about 35 nm, about 40 nm, about 45 nm, about 50 nm, about 75 nm, or about 100 nm. In some embodiments, the average secondary particle size is about 200 nm, about 300 nm, about 400 nm, or about 500 nm. The average particle size of the abrasive grains can be measured by a particle size analyzer (HORIBA Particle Size Distribution tool). Here, the average particle size refers to the average secondary particle size.

[0044] Additionally, the abrasive grains can be further characterized in terms of their specific surface area, which can be obtained using BET techniques. In some embodiments, the abrasive grains have a specific surface area of ​​about 10 m 2 / g ~ approx. 250m 2 / g, approx. 25m 2 / g~about 200m 2 / g, approx. 50m 2 / g ~ approx. 175m 2 / g, approx. 75m 2 / g~about 150m 2 / g, or about 100m 2 / g~about 150m 2 In some embodiments, the abrasive grains comprise a specific surface area in the range of at least about 25 m 2 / g, at least about 50m 2 / g, at least about 75m 2 / g, at least about 100m 2 / g, at least about 125m 2 / g, at least about 150m 2 / g, at least about 175m 2 / g, at least about 200m 2 / g, or at least about 225m 2 Includes specific surface area in g / g.

[0045] Furthermore, the abrasive grains are about 0.5 to about 5 g / cm 3 In some embodiments, the abrasive grains have an average density in the range of at least about 1 g / cm 3 , at least about 1.5 g / cm 3 , at least about 2 g / cm 3 , at least about 2.5 g / cm 3 , at least about 3.0 g / cm 3 , at least about 3.5 g / cm 3 , at least about 4 g / cm 3 , or at least about 5 g / cm 3 has an average density of

[0046] Further, the abrasive grains may include crystals having an average crystallite size of about 1 micron or less. References to crystallite size herein may be the same as references to particle size or the average size of the smallest single crystal structure within the grit of the abrasive grain material. In other examples, the average crystallite size may be smaller, such as about 800 nanometers or less, about 500 nanometers or less, about 300 nanometers or less, or about 200 nanometers or less. In some embodiments, the average crystallite size may be about 175 nanometers or less, about 160 nanometers or less, or about 150 nanometers or less. In some embodiments, the abrasive grains are in the form of alumina crystals having an average crystallite size of at least about 0.1 nanometers, at least about 1 nanometer, at least about 5 nanometers, at least about 10 nanometers, at least about 20 nanometers, at least about 30 nanometers, at least about 40 nanometers, at least about 50 nanometers, or even at least about 80 nanometers. It will be appreciated that the abrasive grains may be made of alumina crystals having an average crystallite size within a range between any of the minimum and maximum values ​​listed above.

[0047] In certain other examples, the abrasive grains can have a finer grit size, including, for example, an average particle size of about 1.5 millimeters or less, about 1 millimeter or less, about 500 microns or less, about 300 microns or less, about 100 microns or less, about 50 microns or less, about 10 microns or less, about 1 micron or less, about 0.8 microns or less, or even about 0.6 microns or less. In some embodiments, the finer grit size of the abrasive grains ranges from about 0.5 microns to about 2 millimeters, from about 1 micron to about 1 millimeter, or from about 1 micron to about 500 microns.

[0048] In some embodiments, the amount of abrasive in the polishing composition is about 0.01 wt% or more, about 0.05 wt% or more, about 0.1 wt% or more, about 0.2 wt% or more, about 0.25 wt% or more, about 0.5 wt% or more, about 0.75 wt% or more, about 1 wt% or more, about 2 wt% or more, or about 3 wt% or more. Alternatively or additionally, the amount of abrasive in the polishing composition can be about 3 wt% or less, about 2.5 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.75 wt% or less, about 0.5 wt% or less, or about 0.1 wt% or less. In some embodiments, the amount of abrasive grains in the polishing composition may be in the range of about 0.01 wt% to about 5 wt%, about 0.01 wt% to about 4.5 wt%, about 0.1 wt% to about 4.0 wt%, about 1.0 wt% to about 3.5 wt%, about 1.5 wt% to about 3.0 wt%, or about 2.0 wt% to about 3.0 wt%. In some embodiments, the amount of abrasive grains is about 0.1 wt%, about 0.25 wt%, about 0.5 wt%, about 0.75 wt%, about 1 wt%, about 1.5 wt%, about 2 wt%, about 2.5 wt%, about 3 wt%, about 3.5 wt%, about 4 wt%, about 4.5 wt%, or about 5 wt%. In some embodiments, the amount of abrasive grains in the polishing composition may be in the range of 1.5 wt% to 3.5 wt%. In some embodiments, the amount of alumina can range from 1.5% to 3.5% by weight in the polishing composition.

[0049] In some embodiments, the alumina abrasive grain has an alpha conversion. As used herein, the term "alpha conversion" refers to the conversion of alpha aluminum precursor to alpha alumina. In some embodiments, the alpha alumina conversion can vary. In some embodiments, the alumina abrasive grain has an alpha alumina conversion ranging from about 50% to about 100%, about 55% to about 95%, about 60% to about 90%, about 65% to about 85%, or about 70% to about 80%. In some embodiments, the alpha conversion of the abrasive grain is less than about 100%, less than about 90%, or less than about 80%. In some embodiments, the alpha conversion of the abrasive grain is at least about 50%, about 55%, about 60%, about 65%, or at least about 70%.

[0050] In this specification, the alpha conversion rate is also referred to as the alpha conversion rate. The alpha conversion rate may be a value calculated from the integrated intensity of a diffraction peak (2θ=57.5°) specific to α-alumina in an X-ray diffraction spectrum. More specifically, the alpha conversion rate and crystallite size of alumina may be calculated by performing X-ray diffraction measurement under the following measurement conditions: Equipment: Rigaku Corporation, powder X-ray diffraction equipment Ultima IV X-ray generation voltage: 40 kV Radiation: Cu-Kα1 line Current: 10mA Scan speed: 10° / min Measurement step: 0.01°.

[0051] The alpha conversion rate can be calculated based on the integrated intensity of the diffraction peak (2θ=57.5°) specific to alpha-alumina. The crystallite size can be calculated using powder X-ray diffraction pattern comprehensive analysis software JADE (manufactured by MDI, automatic calculation based on Scherrer's formula).

[0052] 3. pH adjuster The polishing composition may contain at least one pH adjuster for controlling pH. In some embodiments, the pH adjuster is a basic compound (basic pH adjuster). The basic compound may be appropriately selected from various basic compounds having the function of increasing the pH of the polishing composition dissolved therein. For example, inorganic basic compounds such as alkali metal hydroxides, alkaline earth metal hydroxides, various carbonates, and bicarbonates may be used. These basic compounds may be used alone or in combination of two or more.

[0053] Specific examples of alkali metal hydroxides include potassium hydroxide, sodium hydroxide, ammonium hydroxide, etc. Specific examples of carbonates and hydrogen carbonates include ammonium hydrogen carbonate, ammonium carbonate, potassium hydrogen carbonate, potassium carbonate, sodium hydrogen carbonate, sodium carbonate, etc.

[0054] In alternative embodiments, the pH adjusting agent may be a mixture of an acidic agent and a basic agent (such as a buffering agent). In such embodiments, the selection of the acid is not particularly limited, as long as the strength of the acid is sufficient to adjust the pH of the polishing composition of the present invention. In some embodiments, the acidic agent may be an inorganic acid or an organic acid. For example, but not limited to, such inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid.

[0055] For example, but not limited to, such organic acids include formic acid, acetic acid, chloroacetic acid, propionic acid, butanoic acid, valeric acid, 2-methylbutyric acid, N-hexanoic acid, 3,3-dimethylbutanoic acid, 2-ethylbutanoic acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citrate, citric acid, lactic acid, diglycolic acid, 2-furan carboxylic acid, 3-furan carboxylic acid, 2-tetrahydrofuran carboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, and phenoxyacetic acid. Such organic acids also include, but are not limited to, organic sulfonic acids, such as methanesulfonic acid, ethanesulfonic acid, and isethionic acid.

[0056] In alternative embodiments, the pH adjusting agent may be a buffer including phosphates, acetates, borates, sulfonates, carboxylates, and the like.

[0057] The amount of pH adjuster can vary, and typically is an amount sufficient to achieve and / or maintain the desired pH of the polishing composition, eg, within the ranges described herein.

[0058] In one embodiment, the pH of the polishing composition is adjusted to a range of about 8.0 to about 13.0, about 8.5 to about 13.0, about 9.0 to about 13.0, about 9.5 to about 13.0, about 10 to about 13.0, about 10.5 to about 13, about 11.0 to about 13.0, about 11.5 to about 13.0, about 12.0 to about 13.0, or about 12.5 to about 13.0. In one embodiment, the pH of the polishing composition can be adjusted to a range of 9 to 10.

[0059] In one embodiment, the pH of the polishing composition is adjusted to greater than about 8.0, greater than about 8.5, greater than about 9.0, greater than about 9.5, greater than about 10.0, greater than about 10.5, greater than about 11.0, greater than about 11.5, greater than about 12, or greater than about 12.5. In other words, the pH of the polishing vehicle or polishing composition can be about 8 or greater, about 9 or greater, about 10 or greater, about 11 or greater, about 12 or greater, or about 13 or greater.

[0060] In some embodiments, the pH of the polishing composition is adjusted to about 13 or less, about 12 or less, about 11 or less, about 10 or less, or about 9 or less, where the pH is about 8 or greater. In some embodiments, the pH of the polishing composition has a pH greater than 8.

[0061] In some embodiments, the pH of the polishing composition is about 8, about 8.5, about 9, about 9.5, about 10, about 10.5, about 11, about 11.5, about 12, about 12.5, or about 13.

[0062] The pH adjuster may be present in a particular concentration range regardless of the pH. For example, in some embodiments, the amount of pH adjuster ranges from about 0.0001% to about 1% by weight, from about 0.005% to about 0.5% by weight, or from about 0.001% to about 0.1% by weight. In alternative embodiments, the amount of pH adjuster ranges from about 0.0001% to about 0.0010% by weight, from about 0.0003% to about 0.0009% by weight, or from about 0.0005% to about 0.0008% by weight. In alternative embodiments, the amount of pH adjuster ranges from about 0.0009% to about 0.0040% by weight, or from about 0.0010% to about 0.0030% by weight. In further alternative embodiments, the pH adjuster ranges from about 0.001% to about 0.01% by weight. In some embodiments, the amount of pH adjuster is present in an amount of at least about 0.0001%, at least about 0.0005%, at least about 0.001%, at least about 0.005%, at least about 0.01%, at least about 0.025%, at least about 0.05%, at least about 0.075%, or at least about 0.1% by weight. In some embodiments, the pH adjuster is present in an amount of less than about 0.01%, less than about 0.005%, less than about 0.001%, or less than about 0.0005% by weight. In some embodiments, the pH adjuster is present in an amount that is about 0.0001%, about 0.00025%, about 0.0005%, about 0.0006%, about 0.0007%, about 0.0008%, about 0.0009%, about 0.001%, about 0.005%, about 0.0075%, about 0.01%, about 0.025%, or about 0.05% by weight.

[0063] However, the polishing composition cannot use an excessively large amount of pH adjuster because the amount of ions adversely affects the selectivity, which also limits the types of pH adjusters.

[0064] 4.Water In some embodiments, the polishing composition disclosed herein contains a carrier, medium, or vehicle. In one embodiment, the carrier, medium, or vehicle is water. The water can be ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, or the like. In order to reduce the amount of unnecessary components present in water, the purity of the water can be increased by operations such as removing impurity ions with an ion exchange resin, removing contaminants with a filter, and / or distillation.

[0065] In some embodiments, the water is relatively free of impurities, hi some embodiments, the water contains less than about 10% w / w, less than about 9% w / w, less than about 8% w / w, less than about 7% w / w, less than about 6% w / w, less than about 5% w / w, less than about 4% w / w, less than about 3% w / w, less than about 2% w / w, less than about 1% w / w, less than about 0.9% w / w, less than about 0.8% w / w, less than about 0.7% w / w, less than about 0.6% w / w, less than about 0.5% w / w, less than about 0.4% w / w, less than about 0.3% w / w, or less than about 0.1% w / w of impurities based on the total weight of the water.

[0066] The amount of water in the polishing composition can vary. In some embodiments, water is present in an amount of at least about 50% by weight, at least about 60% by weight, at least about 70% by weight, at least about 80% by weight, at least about 90% by weight, at least about 92% by weight, at least about 94% by weight, at least about 96% by weight, or at least about 98% by weight.

[0067] The polishing composition, including any of the above-described carriers, media, or vehicles, is in the form of a slurry or dispersion.

[0068] In one embodiment, the temperature of the polishing composition may be adjusted to 5 to 30°C, 6 to 20°C, or 7 to 13°C.

[0069] 5. Additional Ingredients In one embodiment, the polishing composition disclosed herein may contain additional components such as a corrosion inhibitor, a carbohydrate, a chelating agent, a biocide, a surfactant, or a cosolvent. Additionally or alternatively, the compositions disclosed herein can include other additives, as would be understood by one of ordinary skill in the art.

[0070] In another embodiment, the additional component may include a corrosion inhibitor. Non-limiting examples of the corrosion inhibitor may include 2-methyl-3-butyn-2-ol, 3-methyl-2-pyrazolin-5-one, 8-hydroxyquinoline and dicyandiamide, benzotriazole and its derivatives, pyrazole and its derivatives, imidazole and its derivatives, benzimidazole and its derivatives, isocyanurate and its derivatives, and mixtures thereof. The amount of the corrosion inhibitor in the polishing composition may be in the range of about 0.0005wt% to 0.25wt%, preferably 0.0025wt% to 0.15wt%, more preferably 0.05wt% to 0.1wt%.

[0071] In another embodiment, the polishing composition does not contain a corrosion inhibitor. As used herein, the term "corrosion inhibitor-free" means that the polishing composition does not contain compounds known in the art to be used as corrosion inhibitors.

[0072] In one embodiment, the additional component may include a carbohydrate. The carbohydrate may include a sugar, and in some embodiments, the sugar is a polysaccharide known as pullulan. The polysaccharide pullulan is composed of maltotriose units in which three α-1,4 linked glucose molecules are further linked by α-1,6 bonds.

[0073] In an alternative embodiment, the polishing composition is carbohydrate-free. As used herein, the term "carbohydrate-free" means that the polishing composition does not contain compounds known in the art as carbohydrates.

[0074] In another embodiment, the additional component may include a chelating agent. The term chelating agent is intended to mean any substance that chelates a metal, such as copper, in the presence of an aqueous solution. Non-limiting examples of chelating agents include inorganic acids, organic acids, amines and amino acids, such as glycine, alanine, citric acid, acetic acid, maleic acid, oxalic acid, malonic acid, phthalic acid, succinic acid, nitrilotriacetic acid, iminodiacetic acid, ethylenediamine, CDTA and EDTA.

[0075] In another embodiment, the polishing composition does not contain a chelating agent. The term "chelating agent-free" used herein means that the polishing composition does not contain a compound known in the art as a chelating agent. Non-limiting examples of chelating agents include compounds such as glycine, alanine, citric acid, acetic acid, maleic acid, oxalic acid, malonic acid, phthalic acid, succinic acid, nitrilotriacetic acid, iminodiacetic acid, ethylenediamine, CDTA and EDTA.

[0076] In one embodiment, the additional component may be a biocide. Non-limiting examples of biocides include hydrogen peroxide, quaternary ammonium compounds, and chlorine compounds. More specific examples of quaternary ammonium compounds include, but are not limited to, methylisothiazolinone, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, alkylbenzyldimethylammonium chloride, and alkylbenzyldimethylammonium hydroxide, with alkyl chains ranging from 1 to about 20 carbon atoms. More specific examples of chlorine compounds include, but are not limited to, sodium chlorite and sodium hypochlorite. Further examples of biocides include biguanides, aldehydes, ethylene oxide, isothiazolinones, iodophors, the KATHON™ and NEOLENE™ product families available from Dow Chemicals, and the Preventol™ family from Lanxess. The amount of the biocide used in the polishing composition can range from about 0.0001 wt% to 0.10 wt%, 0.0001 wt% to 0.005 wt%, or 0.0002 wt% to 0.0025 wt%.

[0077] In another embodiment, the additional component may include a surfactant. The surfactant may be anionic, cationic, nonionic, or zwitterionic and may increase the lubricity of the vehicle or composition. Non-limiting examples of surfactants are dodecyl sulfate, sodium or potassium salt, lauryl sulfate, secondary alkane sulfonate, alcohol ethoxylate, acetylenic diol surfactant, quaternary ammonium surfactant, amphoteric surfactant such as betaine and amino acid derivative surfactant, and any combination thereof. Examples of suitable commercially available surfactants include the TRITON™, Tergitol™, and DOWFAX™ families of surfactants manufactured by Dow Chemicals, as well as various surfactants in the SURFYNOL™, DYNOL™, Zetasperse™, Nonidet™, and Tomadol™ surfactant families manufactured by Air Products and Chemicals. Suitable surfactants of the surfactant may also include polymers containing ethylene oxide (EO) and propylene oxide (PO) groups. An example of an EO-PO polymer is Tetronic™ 90R4 manufactured by BASF Chemicals. An example of an acetylenic diol surfactant is Dynol™ 607 manufactured by Air Products and Chemicals. The amount of surfactant used in the polishing composition can range from about 0.0005 wt% to 0.15 wt%, 0.001 wt% to 0.05 wt%, or 0.0025 wt% to 0.025 wt%.

[0078] In another embodiment, the additional component may include another solvent, called a co-solvent. Non-limiting examples of co-solvents include, but are not limited to, alcohols (such as methanol or ethanol), ethyl acetate, tetrahydrofuran, alkanes, tetrahydrofuran, dimethylformamide, toluene, ketones (such as acetone), aldehydes, and esters. Other non-limiting examples of co-solvents include dimethylformamide, dimethylsulfoxide, pyridine, acetonitrile, glycols, and mixtures thereof. Co-solvents may be used in various amounts, preferably from lower limits of about 0.0001, 0.001, 0.01, 0.1, 0.5, 1, 5, or 10 (wt%) to upper limits of about 0.001, 0.01, 0.1, 1, 5, 10, 15, 20, 25, or 35 (wt%).

[0079] Thus, as described herein, in some embodiments, a polishing composition comprises an oxidizer and an abrasive, wherein the oxidizer comprises a complex metal oxide, the abrasive comprises alumina, and the pH of the composition is about 8 or greater.

[0080] The polishing composition as in any embodiment above, wherein the oxidizing agent comprises potassium permanganate.

[0081] A polishing composition as in any embodiment above, wherein the abrasive comprises alpha alumina.

[0082] The polishing composition, as in any of the above embodiments, wherein the abrasive has an isoelectric point in the range of about 5 to about 7.

[0083] A polishing composition as in any embodiment above, wherein the oxidizing agent is potassium permanganate and the abrasive is alumina.

[0084] The polishing composition, as in any embodiment above, wherein the pH is adjusted with a pH adjuster, such as potassium hydroxide.

[0085] The polishing composition, as in any embodiment above, wherein the oxidizing agent is present in an amount of about 1.5% to about 3.5% by weight.

[0086] The polishing composition, as in any embodiment above, wherein the abrasive is present in an amount from about 1.5% to about 3.5% by weight.

[0087] The polishing composition as in any of the above embodiments, wherein the oxidizing agent is potassium permanganate and is present in an amount from about 1.5% to about 3.5% by weight.

[0088] The polishing composition as in any of the above embodiments, wherein the abrasive is alumina and is present in an amount from about 1.5% to about 3.5% by weight.

[0089] The polishing composition as in any of the above embodiments, wherein the oxidizing agent is potassium permanganate and is present in an amount of about 1.5 wt % to about 3.5 wt % and the abrasive is alumina and is present in an amount of about 1.5 wt % to about 3.5 wt %.

[0090] The polishing composition, as in any of the above embodiments, has a pH of at least 9.

[0091] The polishing composition as in any of the above embodiments, wherein the pH is 10 or less.

[0092] The polishing composition, as in any of the above embodiments, further comprises a carrier (eg, water).

[0093] As in any of the above embodiments, the polishing composition is in the form of a slurry.

[0094] C. Method of Using the Polishing Composition The polishing compositions described herein are useful for polishing any suitable substrate comprising poly-SiC. In some embodiments, the substrate comprises at least one layer of poly-SiC. In some embodiments, the at least one layer comprising poly-SiC is on the surface of the substrate, i.e., on the top layer of the substrate. The poly-SiC-containing surface may be in the form of a wafer or a thin (or thick) film.

[0095] Silicon carbide used in semiconductors can be single crystal or polycrystalline, examples of such polymorphs are cubic (e.g., 3C silicon carbide) or non-cubic (e.g., 4H silicon carbide, 6H silicon carbide), or a mixture of polymorphs (i.e., poly-SiC). The advantage of using poly-SiC is the low cost of the substrate. Some distinguishing features of poly-SiC are that it typically does not have the same polarity (Si / C surface) as single crystal 4H-SiC, is black, and is opaque.

[0096] A further feature of poly-SiC is that it consists of many polymorphs (e.g., 4H, 3C, and various other polymorphs), so voids (vacancies) may exist at the grain boundaries. The different polymorphs in poly-SiC result in a difficult crystallinity with a wide variation in poly-SiC. Also, the density of poly-SiC is 3.21 g / cm3, which is higher than that of 4H-SiC. 3 The density of poly-SiC is 3.20 g / cm 3 or less, 3.19 g / cm 3 or less, 3.18 g / cm 3 or less, 3.17 g / cm 3 or less, 3.16 g / cm 3 The density of poly-SiC may be 3.10 g / cm or less. 3 or more, 3.15 g / cm 3 or more, 3.16 g / cm 3 or more, 3.17 g / cm 3 or more, 3.18 g / cm 3 or more, 3.19 g / cm 3 or more, 3.20 g / cm 3 Because of these and other characteristics, it is difficult to obtain high removal rates and the desired smoothness of poly-SiC during CMP, which increases manufacturing time and associated costs.

[0097] Therefore, an object of the present invention is to provide a method for polishing poly-SiC that has a high removal rate of poly-SiC and a desired smoothness.

[0098] Polishing of materials including poly-SiC can be beneficial in a variety of applications, including, but not limited to, flat panel displays, integrated circuits, memory or rigid disks, metals, interlayer dielectric (ILD) devices, semiconductors, microelectromechanical systems, ferroelectrics, and magnetic bands.

[0099] Thus, in some embodiments, the subject matter disclosed herein relates to a method for polishing a poly-SiC-containing substrate with a polishing composition disclosed herein. In some embodiments, the method for polishing a poly-SiC-containing substrate includes the steps of: (a) providing a poly-SiC-containing substrate; (b) providing a polishing composition described herein; (c) applying the polishing composition to at least a portion of the substrate; and (d) polishing at least a portion of the substrate with the polishing composition to polish the substrate.

[0100] In some embodiments, the apparatus used in the polishing method disclosed herein is a chemical mechanical polishing (CMP) apparatus, although the disclosed method should not be limited thereto. Typically, the apparatus comprises a platen that is in motion during use and has a velocity resulting from an orbital, linear, or circular motion, a polishing pad that contacts the platen and moves with the platen when in motion, and a carrier that contacts the surface of the polishing pad and holds a substrate to be polished by moving relative to the surface of the polishing pad. The polishing of the substrate is performed by placing the substrate in contact with a polishing pad and a polishing composition (generally placed between the substrate and the polishing pad) and moving the polishing pad relative to the substrate to polish at least a portion of the substrate to polish the substrate. The polishing endpoint can then be determined by monitoring the weight of the poly-SiC-containing substrate, which is used to calculate the amount of poly-SiC removed from the substrate. Such techniques are well known in the art.

[0101] The polishing pad used here is not particularly limited. For example, any polishing pad can be used, such as a nonwoven type, a suede type, a polyurethane type including a hard foam type and a soft foam type, a type including abrasive grains, a type not including abrasive grains, etc.

[0102] Polishing refers to the removal of at least a portion of a surface to polish the surface. Polishing can be performed to provide a surface with reduced surface roughness by removing grooves, crates, pits, etc., but polishing can also be performed to introduce or restore a surface shape characterized by the intersection of planar segments.

[0103] Poly-SiC can be removed at any suitable rate to achieve polishing of the substrate in the polishing method disclosed herein. In some embodiments, the polishing composition used in the disclosed polishing method has a removal rate (RR) in the range of about 1 μm / hr to about 10 μm / hr, about 2 μm / hr to about 8 μm / hr, about 3 μm / hr to about 7 μm / hr, about 4 μm / hr to about 7 μm / hr, about 4.5 μm / hr to about 6.5 μm / hr, or about 5.0 μm / hr to about 6.0 μm / hr. In some embodiments, the RR is in the range of about 6.0 μm / hr to about 7.0 μm / hr. In some embodiments, RR is at least about 1.0 μm / hr, about 2.0 μm / hr, about 3.0 μm / hr, about 4.0 μm / hr, about 4.5 μm / hr, about 5.0 μm / hr, about 5.5 μm / hr, about 6.0 μm / hr, or about 7.0 μm / hr. In some embodiments, RR is less than about 10.0 μm / hr, about 9.0 μm / hr, about 8.0 μm / hr, about 7.0 μm / hr, about 6.5 μm / hr, about 5.0 μm / hr, about 4.5 μm / hr, about 4.0 μm / hr, about 3.0 μm / hr, about 2.0 μm / hr, or about 1.0 μm / hr.

[0104] In some embodiments, the polishing method disclosed herein uses a polishing composition having a specific average roughness index (Ra). In some embodiments, the Ra of the polishing composition is in the range of about 0.01 nm to about 1.50 nm, about 0.01 nm to about 1.20 nm, about 0.10 nm to about 1.2 nm, about 0.25 nm to about 1.20 nm, about 0.50 nm to about 1.20 nm, about 0.6 nm to about 0.90 nm, or about 0.70 nm to about 0.90 nm. In some embodiments, the Ra of the polishing composition used in the disclosed polishing method is less than about 1.20 nm, less than about 1.10 nm, less than about 1.0 nm, less than about 0.90 nm, less than about 0.80 nm, less than about 0.70 nm, less than about 0.60 nm, less than about 0.50 nm, less than about 0.40 nm, or less than about 0.30 nm.

[0105] In some embodiments, the polishing method disclosed herein uses a polishing composition having a specific average roughness depth (Rz). In some embodiments, the Rz of the polishing composition is in the range of about 1 nm to about 20 nm, about 5 nm to about 15 nm, about 6 nm to about 12 nm, about 7 nm to about 10 nm, about 8 nm to about 10 nm, or about 9 nm to about 10 nm. In some embodiments, the Rz of the polishing composition is less than about 15 nm, about 14 nm, about 13 nm, about 12 nm, about 11 nm, about 10 nm, about 9.75 nm, about 9.50 nm, about 9.25 nm, about 9.00 nm, 8.75 nm, about 8.50 nm, about 8.25 nm, about 8.0 nm, 7.75 nm, about 7.5 nm, about 7.25 nm, about 7.00 nm, or about 6.50 nm.

[0106] In some embodiments, the polishing methods disclosed herein use any suitable head pressure, hi some embodiments, the head pressure of the polishing method ranges from about 1.4 psi to about 22 psi, from about 2.9 psi to about 14.5 psi, from about 3 psi to about 12 psi, from about 4 psi to about 10 psi, from about 5 psi to about 9 psi, or from about 6 psi to about 8 psi.

[0107] In some embodiments, the polishing methods disclosed herein use any suitable platen rotation speed, hi some embodiments, the platen rotation speed of the polishing method is in the range of about 60 rpm to about 180 rpm, about 70 rpm to about 170 rpm, about 80 rpm to about 160 rpm, about 90 rpm to about 150 rpm, about 100 rpm to about 140 rpm, or about 110 rpm to about 130 rpm.

[0108] In some embodiments, the polishing methods disclosed herein use any suitable head rotation speed, in some embodiments, the head rotation speed of the polishing method is in the range of about 90 rpm to about 200 rpm, about 100 rpm to about 190 rpm, about 110 rpm to about 180 rpm, about 120 rpm to about 170 rpm, about 130 rpm to about 160 rpm, or about 140 rpm to about 150 rpm.

[0109] In some embodiments, the polishing methods disclosed herein use any suitable pressure rate (PV), hi some embodiments, the PV of the polishing method ranges from about 300 psi*in / sec to about 900 psi*in / sec, from about 350 psi*in / sec to about 850 psi*in / sec, from about 400 psi*in / sec to about 800 psi*in / sec, or from about 450 psi*in / sec to about 750 psi*in / sec.

[0110] Thus, in some embodiments, described herein is a method of using a polishing composition, comprising: a) providing a polishing composition disclosed herein (e.g., claim 1); b) providing a substrate comprising a polycrystalline silicon carbide (poly-SiC)-containing layer; and c) polishing the substrate with the polishing composition to provide a polished substrate.

[0111] As in any embodiment above, the substrate is a semiconductor.

[0112] As with any embodiment above, the method provides a poly-SiC removal rate in the range of about 4 μm / hr to about 7 μm / hr.

[0113] As in any embodiment above, the polished substrate has a roughness index (Ra) of less than about 1.2 nm.

[0114] As in any of the above embodiments, the polished substrate has a specified average roughness depth (Rz) of less than about 10 nm.

[0115] As in any of the embodiments described above, the polishing composition contains abrasive grains having an isoelectric point in the range of about 5 to about 7. The isoelectric points of the polishing compositions in the examples described below were in the range of about 5 to about 7.

[0116] As in any embodiment above, the polishing composition comprises an abrasive that does not contain transition phase alumina.

[0117] As in any embodiment above, the polishing composition contains an oxidizing agent that is potassium permanganate.

[0118] As in any of the above embodiments, the polishing composition further comprises a pH adjuster present in an amount of less than about 0.001 wt. %.

[0119] As with any of the embodiments described above, the polishing composition has a pH in the range of about 9 to about 10.

[0120] D. [Example] The following preparations and examples are given to enable those skilled in the art to more clearly understand and to practice the present invention, and they are not to be construed as limiting the scope of the invention, but merely as illustrative and representative thereof.

[0121] In one embodiment, a method of making the polishing composition is disclosed. In another embodiment, a method of using the polishing composition to polish a material is disclosed.

[0122] [Example 1] Abrasive grain evaluation The average secondary particle size of the alumina abrasive grains was measured using a laser diffraction / scattering type particle size distribution measuring device (LA-950, manufactured by Horiba, Ltd.) and is shown in Table 1.

[0123] [Table 1]

[0124] Example 2 Measurement of Removal Rate (RR), Roughness Index (Ra) and Average Roughness Depth (Rz) of Experimental Slurries Table 2 below shows the general settings of the polishing equipment and polishing parameters used.

[0125] [Table 2]

[0126] *The cooler is a device that cools the polishing platen. The cooler temperature is the value obtained by measuring the pad surface temperature near the head / substrate during polishing with a radiation thermometer. *Poly-SiC is polycrystalline, so the polished surface contains a mixture of various crystal orientations, Si faces, and C faces. By reducing the speed selectivity of each, the Ra (nm) and Rz (nm) of the polished surface can be reduced.

[0127] Test conditions / parameters for Table 2: (a) The REVSUM6EC2 was used for single-sided polishing of a platen approximately 22 inches in diameter.

[0128] (b) A RohmanHaas IC1000k grooved pad, a hard polyurethane polishing pad, was selected.

[0129] (c) KINIK 179B was used as the pad conditioner, with a conditioning sequence lasting approximately 2 minutes prior to test sanding at 5 pounds.

[0130] (d) During the polishing test, the chiller temperature was set at 10°C.

[0131] (e) A slurry flow rate of 50 ml / min was used.

[0132] (f) Polishing conditions included a head pressure of 7.0 psi, and platen and head rotation speeds of 120 and 145 rpm, respectively.

[0133] (g) The polishing time was 5 min.

[0134] [Table 3]

[0135] Table 3 above shows the general methodology used to evaluate the polishing of wafers.

[0136] Test conditions / parameters: (a) A 6 inch poly-SiC test wafer was used that can be purchased from a conventional supplier.

[0137] (b) Test wafer 1 has a nominal mirror finish once polished, with an Ra of less than 7 nm and a density of 3.15 g / cm 3 It is assumed that the SORI is less than 50 μm. For test wafer 2, the nominal once-polished mirror finish is less than 7 nm Ra and 3.2 g / cm density. 3 It is assumed that the SORI is less than 50 μm. Note that "once polished" means that the provider has already polished the test wafer 1 and the test wafer 2.

[0138] (c) The wafer was cleaned by 1) a PVA wipe with organic acid and surfactant (i.e., CMP-MO2 from Kanto Chemical Co., Ltd. diluted 10 times with HO), followed by 2) an RCA-based clean such as a sulfuric acid and hydrogen peroxide mixture (SPM), and 3) a hydrofluoric acid clean.

[0139] (d) RR was calculated using the weight loss and crystal density before and after CMP after substrate cleaning, which was performed using the polishing composition of Example 3 (Comparative Study).

[0140] (e) Surface roughness was evaluated by observing the Ra and Rz values ​​using an atomic force microscope (AFM). The measurement area was 10 microns.

[0141] Since poly-SiC has no polarity, when testing RR and Ra / Rz, both surfaces were treated as having the same characteristics. RR and Ra evaluations were performed using one set on each side. First, RR was calculated by weight loss conversion, and then the substrate was cleaned and measured with AFM. In addition, to avoid the influence of residual stress on the polished surface, one-sided evaluations were performed alternately.

[0142] Example 3 Comparative Study (Comparative study 1) Preparation procedure of polishing composition: Alumina A was prepared as abrasive grains, and mixed in water so that the total content of abrasive grains (powder) was the value shown in Table 4-1. Next, potassium permanganate, an oxidizing agent, was added so that the content was the content shown in Table 4-1, and the mixture was stirred at room temperature (25°C) for 30 minutes to prepare a dispersion. While checking the pH of the dispersion with a pH meter (manufactured by Horiba, Ltd.), KOH or HNO3 was added as a pH adjuster to adjust the pH to the value shown in Table 4-1 to prepare a polishing composition.

[0143] In comparative study 1, test wafer 1 was used.

[0144] [Table 4-1]

[0145] According to the polishing composition of one embodiment of the present invention, when a low-density test wafer 1 is polished, Ra and Rz can be reduced while maintaining a high RR. Since a low-density wafer is likely to have pits and grains, when this wafer is polished, RR is likely to be high while Ra and Rz are likely to deteriorate. For this reason, a polishing composition that can reduce Ra and Rz while maintaining a high RR is useful for low-density wafers. In contrast, although RR is high in Comparative Examples 1 to 6 and 8, Ra and Rz cannot be sufficiently reduced. In addition, in Comparative Example 7, RR is low and Ra and Rz cannot be sufficiently reduced. (Comparative study 2) Preparation procedure of polishing composition: Alumina A was prepared as abrasive grains, and mixed in water so that the total content of abrasive grains (powder) was the value shown in Table 4, 2. Next, potassium permanganate, an oxidizing agent, was added to the content shown in Table 4, 2, and stirred at room temperature (25°C) for 30 minutes to prepare a dispersion. While checking the pH of the dispersion with a pH meter (manufactured by Horiba, Ltd.), KOH or HNO3 was added as a pH adjuster to adjust the pH to the value shown in Table 4, 2, to prepare a polishing composition.

[0146] In comparative study 2, test wafer 2 was used.

[0147] [Table 4-2]

[0148] According to the polishing composition of one embodiment of the present invention, when a high-density test wafer 2 is polished, RR can be improved while suppressing increases in Ra and Rz. Since a high-density wafer has performance close to that of a single crystal wafer, when this wafer is polished, Ra and Rz are low, but RR is difficult to improve. Therefore, a polishing composition that can improve RR while suppressing increases in Ra and Rz is useful for high-density wafers. In contrast, Comparative Example 9 and Comparative Example 10 have high RR, but Ra and Rz are deteriorated. Moreover, Comparative Examples 11 to 14 have low Ra and Rz, but low RR values.

[0149] In some embodiments, the density of poly-SiC is 3.18 g / cm 3 In some embodiments, the density of the poly-SiC is 3.18 g / cm 3 is less than.

[0150] In some embodiments, the content of the oxidizing agent and the content of the abrasive grains in the polishing composition are preferably both more than 1.5% by weight.

[0151] Example 4 Relationship between pH and oxidation-reduction potential ORP of polishing composition The polishing compositions of the present invention 1, 2, 5, and 6 were prepared, and the pH was adjusted to the acidic side by using HNO3, and to the alkaline side by using KOH, as shown in the following table. Then, the oxidation-reduction potential ORP at each pH was measured.

[0152] [Table 5-1]

[0153] [Table 5-2]

[0154] [Table 5-3]

[0155] [Table 5-4]

[0156] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other aspects of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

[0157] The present invention encompasses the following aspects and configurations.

[0158] 1. A polishing composition comprising an oxidizing agent, an abrasive, and water, wherein the oxidizing agent is permanganate present in an amount of about 1.5% to about 3.5% by weight, the abrasive is alumina present in an amount of about 1.5% to about 3.5% by weight, and the polishing composition has a pH of greater than about 8.

[0159] 2. The polishing composition according to 1., wherein the abrasive grains have an isoelectric point in the range of about 5 to about 7.

[0160] 3. A polishing composition according to 1. or 2., wherein the oxidizing agent is potassium permanganate.

[0161] 4. The polishing composition according to any one of 1. to 3., further comprising a pH adjuster present in an amount of less than about 0.001 wt. %.

[0162] 5. The polishing composition according to 4., wherein the pH adjuster is a basic pH adjuster.

[0163] 6. The polishing composition according to 5., wherein the pH adjuster is potassium hydroxide.

[0164] 7. The polishing composition according to any one of 1. to 6., which has a pH in the range of about 9 to about 10.

[0165] 8. The polishing composition according to any one of 1. to 7., wherein the polishing composition has a poly-SiC removal rate of about 4 μm / hour to about 7 μm / hour.

[0166] 9. A method for polishing a substrate containing polycrystalline silicon carbide, comprising the steps of: a) providing a polishing composition described in any one of 1. to 7.; b) providing a substrate containing a polycrystalline silicon carbide (poly-SiC)-containing layer; and c) polishing the substrate with the polishing composition to obtain a polished substrate.

[0167] 10. The method of claim 9, wherein the substrate is a semiconductor.

[0168] 11. The method of claim 9 or 10, wherein the method results in a poly-SiC removal rate in the range of about 4 μm / hr to about 7 μm / hr.

[0169] 12. The method according to any one of 9. to 11., wherein the polished substrate has a roughness index (Ra) of less than about 1.2 nm.

[0170] 13. A method according to any one of 9. to 12., wherein the polished substrate has a specific average roughness depth (Rz) of less than about 13 nm.

[0171] 14. The method according to any one of 9. to 13., wherein the polishing composition contains abrasive grains having an isoelectric point in the range of about 5 to about 7.

[0172] 15. The method according to any one of 9. to 14., wherein the polishing composition contains an oxidizing agent which is potassium permanganate.

[0173] 16. The method according to any one of 9. to 15., wherein the polishing composition has a pH in the range of about 9 to about 10.

[0174] This application is based on a U.S. provisional patent application (Application No. 63-288039) filed on December 10, 2021, the disclosure of which is incorporated by reference in its entirety into this specification.

Claims

1. A polishing composition comprising an oxidizing agent, an abrasive grain, and water, the oxidizing agent is permanganate present in an amount of about 1.5% to about 3.5% by weight; A polishing composition wherein the abrasive is alumina present in an amount of about 1.5% to about 3.5% by weight, and wherein the polishing composition has a pH greater than about 8.

2. 2. The polishing composition of claim 1, wherein the abrasive has an isoelectric point in the range of about 5 to about 7.

3. The polishing composition of claim 1 , wherein the oxidizing agent is potassium permanganate.

4. The polishing composition of claim 1 , further comprising a pH adjuster present in an amount less than about 0.001 wt %.

5. The polishing composition according to claim 4 , wherein the pH adjuster is a basic pH adjuster.

6. The polishing composition according to claim 5 , wherein the pH adjuster is potassium hydroxide.

7. 2. The polishing composition of claim 1, wherein the pH is in the range of about 9 to about 10.

8. 10. The polishing composition of claim 1, wherein the polishing composition has a poly-SiC removal rate of about 4 μm / hr to about 7 μm / hr.

9. 1. A method of polishing a substrate comprising polycrystalline silicon carbide, comprising: a) providing the polishing composition of claim 1; b) providing a substrate including a polycrystalline silicon carbide (poly-SiC)-containing layer; and c) polishing the substrate with the polishing composition to obtain a polished substrate.

10. The method of claim 9 , wherein the substrate is a semiconductor.

11. The method of claim 9, wherein the method results in a poly-SiC removal rate in the range of about 4 μm / hr to about 7 μm / hr.

12. 10. The method of claim 9, wherein the polished substrate has a roughness index (Ra) of less than about 1.2 nm.

13. 10. The method of claim 9, wherein the polished substrate has a specific average roughness depth (Rz) of less than about 13 nm.

14. The method of claim 9, wherein the polishing composition comprises an abrasive having an isoelectric point in the range of about 5 to about 7.

15. The method of claim 9 , wherein the polishing composition comprises an oxidizing agent that is potassium permanganate.

16. The method of claim 9, wherein the polishing composition has a pH in the range of about 9 to about 10.

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