TW202338058A - Polishing compositions for silicon carbide surfaces and methods of use thereof - Google Patents

Abstract

The present disclosure relates to chemical-mechanical polishing (CMP) compositions for polishing polycrystalline silicon carbide-containing surfaces. More particularly, the polishing compositions are in the form of a slurry with a pH of 8 or more comprising an oxidant and an abrasive.

Description

Abrasive compositions for silicon carbide surfaces and methods of using the same

The present invention relates to chemical mechanical polishing (CMP) compositions for polishing surfaces containing polycrystalline silicon carbide. More specifically, the grinding compositions disclosed herein are in the form of a slurry with a pH of 8 or greater, including an oxidizing agent and an abrasive.

Chemical mechanical polishing (CMP) is a method in which material is removed from the surface of a substrate, such as a semiconductor wafer, and the surface is ground (planarized) by combining a physical process such as abrasion with a chemical process such as oxidation. In its most basic form, CMP involves applying a slurry to the surface of a substrate or to a polishing pad that polishes the substrate. This method achieves both removal of unwanted material and planarization of the substrate surface. The removal or grinding methods are not intended to be purely physical or purely chemical, but rather involve a synergistic combination of both.

CMP is used on a variety of objects, examples of which include silicon dioxide (SiO ₂ ) between layers or embedded in dielectrics, metals such as aluminum (Al), copper (Cu), and tungsten (W) in wiring layers or connections Plugs to such wiring layers, barrier metal layers such as tantalum (Ta), tantalum nitride (TaN) and titanium (Ti), and polycrystalline silicon carbide (polycrystalline SiC) in materials such as semiconductors.

Typically, silicon substrates are used in semiconductor manufacturing. However, further development is limited due to the inherent properties of silicon. The development of next-generation semiconductor devices has focused on the use of materials with greater hardness and other unique properties. For example, when compared to silicon oxide, silicon carbide has higher thermal conductivity, greater radiation tolerance, higher dielectric strength, and is able to withstand higher temperatures. However, the use of silicon carbide has been limited by semiconductor manufacturing technology.

In order to produce silicon carbide semiconductors, the surface of the silicon carbide substrate must be ground in a manner that provides a smooth surface and precise surface dimensions. To date, adaptation of CMP technology for silicon carbide grinding has been relatively unsuccessful. Polishing compositions containing colloidal silica produce low silicon carbide removal rates and therefore require lengthy polishing cycles at temperatures of approximately 50° C. for several hours, which may result in damage to the silicon carbide substrate. See, for example, Zhou et al., J. Electrochemical Soc., 144, pp. L161-L163 (1997); Neslen et al., J. Electronic Materials, 30, pp. 1271-1275 (2001). Long polishing cycles add considerable cost to the process and are a barrier to widespread use of silicon carbide in the semiconductor industry.

Silicon carbide used in semiconductors can be single crystal or polycrystalline. Silicon carbide has many different types of crystal structures, each with its own unique set of electronic properties. However, only a few of these polytypes can be reproduced in forms acceptable for use as semiconductors. Such polytypes may be cubic (eg, 3C silicon carbide) or non-cubic (eg, 4H silicon carbide, 6H silicon carbide) or a mixture of polytypes (ie, polycrystalline).

In addition to the differences between polytypes, there are significant differences between single crystal forms and polycrystalline silicon carbide. For example, single crystal silicon carbide substrates are used in the production of semiconductors to produce single crystal silicon carbide substrates that are more expensive to produce. In addition, if the substrate is subjected to a thermal process or the like, slip dislocations in the crystal may occur, resulting in deformation of the substrate.

Compared to the use of monocrystalline SiC substrates, polycrystalline SiC substrates can be produced relatively cheaply. In order to construct a SiC power semiconductor device, it is necessary to form a drift layer on a single crystal SiC substrate by epitaxial crystallization and to form gates, electrodes, etc. on the drift layer. The processing cost of using expensive single crystal substrates alone is a major issue limiting the widespread use of devices containing single crystal SiC. The use of polycrystalline SiC will reduce processing costs because: i) the surface layer of a single crystal SiC substrate of only a few microns is used as the bulk epitaxial junction layer of the SiC power semiconductor; and ii) the polycrystalline SiC is used as the laminate substrate The supporting substrate (see https://www.chusho.meti.go.jp/keiei/sapoin/portal/seika/2015/2720403030h.pdf).

In addition, since the polycrystalline SiC substrate contains a large number of grain boundaries, dislocation slip is prevented and deformation of the substrate is suppressed even after thermal processing. For at least these reasons, polycrystalline SiC is becoming more common in semiconductor production.

However, when chemical mechanical polishing (CMP) is applied to the surface of a substrate containing polycrystalline SiC to obtain a smooth surface, it often results in low removal rates and reduced surface smoothness. This is because in a polycrystalline SiC substrate, polar planes and crystal orientation planes are different from each other, but are mixed and exposed on the surface of the substrate, which produces different grinding removal rates according to the respective planes and planes. In short, because polycrystalline SiC is composed of different crystal plane domains or polytypes, different removal rates are observed for each during the CMP method, making it difficult to achieve both high removal rates and smooth surfaces.

In view of the challenges associated with grinding substrates containing polycrystalline SiC, it is critical to identify grinding compositions that achieve high polycrystalline SiC removal rates while achieving low average roughness. These and other challenges are addressed by the themes revealed in this article. Citation list non-patent literature

[NPL 1] Non-patent document 1: Zhou et al., J. Electrochemical Soc., Volume 144, Pages L161 to L163 (1997) [NPL 2] Non-patent literature 2: Neslen et al., J. Electronic Materials, Volume 30, Pages 1271 to 1275 (2001) [NPL 3] Non-patent literature 3: https://www.chusho.meti.go.jp/keiei/sapoin/portal/seika/2015/2720403030 h.pdf

In accordance with the purposes of the presently disclosed subject matter or the problems to be solved by the present invention, as embodied and broadly described herein, it is an object of the present invention to provide a method for grinding a substrate, such as a substrate containing polycrystalline silicon carbide (polycrystalline SiC) A composition that provides a substrate with a desired surface morphology (ie, surface roughness) when using CMP. Another object of the present invention is to provide an effective method for grinding such polycrystalline SiC-containing substrates using the grinding composition disclosed herein.

Accordingly, the subject matter of the present invention is in one aspect an abrasive composition comprising an oxidizing agent and an abrasive, wherein the composition has a pH of 8 or greater. In some embodiments, the oxidizing agent is a complex metal oxide (eg, potassium permanganate) and the abrasive is alumina. In some embodiments, the oxidizing agent is present in the grinding composition in an amount ranging from about 1.5 wt% to about 3.5 wt%, and the abrasive is present in an amount ranging from about 1.5 wt% to about 3.5 wt%.

In another aspect, the subject matter described herein relates to a method for polishing a substrate, the method comprising the steps of: 1) providing a polishing composition described herein; 2) providing a substrate, wherein the substrate includes a polycrystalline silicon carbide layer; and 3) polishing the substrate with a polishing composition to provide a polished substrate. In some embodiments, the grinding method has a high removal rate (RR). In some embodiments, grinding methods produce substrates with low roughness index (Ra).

These and other aspects are revealed in further detail below.

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

Before the compounds, compositions, articles, systems, devices and/or methods of the present invention are disclosed and described, it is to be understood that it is not limited to particular methods of synthesis unless otherwise stated, or to particular components unless otherwise stated. Because this can of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects 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, example methods and materials are now described.

As described herein, in embodiments, is a grinding composition comprising an oxidizing agent and an abrasive, wherein the composition has a pH of 8 or greater. These polishing compositions are intended to polish substrates containing polycrystalline SiC. The grinding composition exhibits at least one benefit, such as: 1) high removal rate; 2) smooth surface with low Ra; 3) high efficiency and planarization ability; 4) CMP that does not require the use of fine grinding and/or grinding processes method; and 5) lower production costs.

The abrasive compositions described herein have a variety of uses, such as, but not limited to, chemical mechanical polishing of semiconductor wafers containing polycrystalline SiC. A.Definition

Listed below are definitions of various terms used to describe the present invention. These definitions apply to terms as they are used throughout this specification, individually or as part of a larger group, unless otherwise limited in a particular case.

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.

Ranges may 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 from one particular value and/or to another particular value. Similarly, when a value is expressed as an approximation by use of the prefix "about," it is understood that the particular value forms another aspect. It is further understood that the endpoints of each range are significant relative to, and independent of, the other endpoint. It should also be understood that certain values are disclosed herein, and that each value, in addition to the value itself, is also disclosed herein as "about" a particular value. For example, if the value "10" is revealed, then "approximately 10" is also revealed. For example, if the value "approximately 10" is revealed, then "10" is also revealed. It should also be understood that each unit between two specific units is also disclosed. For example, if 10 and 15 are revealed, 11, 12, 13, and 14 are also revealed. As used herein, when there is a description of about X (where X is a numerical value), about X is X ± 10%.

Unless specifically stated to the contrary, weight percent (wt%) of a component is based on the total weight of the vehicle or composition including that component.

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 the circumstances in which the event or circumstance occurs and A situation in which the event or situation does not occur.

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

As used herein, the term "roughness index" (Ra) is a calculated value that characterizes the degree of surface roughness (ie, a surface texture that is not smooth but irregular and uneven). The lower the value, the smoother the surface.

As used herein, the term "specific mean roughness depth" (Rz) is an average calculated from all heights and depths present on a surface, thereby further characterizing the texture of the surface. Ra and Rz can be calculated according to JIS B 0601-2001 or ISO 13565-1:1996. The roughness curve based on Ra and Rz can be measured by the equipment used in the examples described below (atomic force microscope (AFM)). B. Grinding Composition

The basic mechanism of chemical mechanical polishing (CMP) is to soften the surface layer through a chemical reaction, and then use abrasive particles to remove the softened layer through mechanical force. However, the role of CMP is not only material removal, but also planarization, surface smoothing, uniformity control, defect reduction, etc. Semiconductor yield improvements are therefore affected by CMP processing. Surface scratches that can result from CMP are extremely harmful defects in semiconductor manufacturing. Therefore, in order to achieve appropriate CMP performance without surface scratches, the development of abrasive compositions is crucial. CMP requirements may include a planarized surface with a flatness of <13 nm, a rough-free surface with a surface roughness of <1.2 nm, and a defect-free surface with a scratch and pit count of 0 per wafer. In some embodiments, planarization is performed at high removal rates of the desired material to be removed, without contamination and with high productivity. Here, the flattened surface can be evaluated by the Rz index, and the roughness-free surface can be evaluated by the Ra index.

CMP is often used as part of a polishing process to polish surfaces containing polycrystalline SiC. Due to its high hardness level and significant chemical inertness, grinding of surfaces containing polycrystalline SiC can be difficult. Typically, to prepare polycrystalline SiC wafers, multiple grinding steps must be performed that require particles even harder than the polycrystalline SiC itself in order to achieve a reasonable grinding rate. However, the use of such hard particles often leaves the surface highly damaged, such as scratches and dislocations, which typically occur at both the surface and subsurface of the wafer. Accordingly, there would be a great need for CMP slurries and/or methods for grinding polycrystalline SiC that reduce damage and increase grinding rates of polycrystalline SiC-containing materials.

Therefore, in this regard, the present invention is directed to abrasive compositions having a pH of 8 or greater containing composite metal oxides as oxidizing agents and alumina as abrasives. It has been found that these grinding compositions provide high grinding rates and desirable surface morphology, demonstrating reduced damage compared to damage typically observed with conventional grinding methods. Such abrasive compositions and methods of use are disclosed in greater detail below. 1. Oxidizing agent

The grinding compositions disclosed herein contain an oxidizing agent. The oxidizing agent can react with the surface of the object to be ground, thus facilitating the grinding process of various surfaces.

For example, in some embodiments, the oxidizing agent present in the grinding composition includes permanganic acid, such as permanganic acid and its salts, including sodium and potassium permanganate; peroxides, such as hydrogen peroxide; nitric acid Salt compounds, such as nitric acid, its salts, including ferric nitrate, silver nitrate, aluminum nitrate and their complexes, including ceric ammonium nitrate; persulfate compounds, such as persulfuric acid, including peroxymonosulfuric acid, peroxydisulfuric acid and the like substances, 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 Salts, including potassium bromate; iodine-containing compounds, such as iodic acid and its salts, including ammonium iodate, and periodic acid and its salts, including sodium periodate and potassium periodate; ferric acids, such as ferric acid and its salts, Including potassium ferrate; chromic acid, such as chromic acid and its salts, including potassium chromate and potassium dichromate; Vanadic acid, such as vanadate and its salts, including ammonium vanadate, sodium vanadate and potassium vanadate; ruthenic acid , such as perruthenic acid and its salts; molybdic acid, such as molybdic acid and its salts, including ammonium molybdate and disodium molybdate; rhenic acid, such as perrhenic acid and its salts; and tungstic acid, such as tungstic acid and its salts , including disodium tungstate. These may be used alone or in combination of two or more types as appropriate.

In some embodiments, the oxidizing agent present in the abrasive composition includes a complex metal oxide. Examples of composite metal oxides include, but are not limited to, metal nitrates, ferric acid, permanganic acid, chromic acid, vanadic acid, ruthenic acid, molybdic acid, rhenic acid, and tungstic acid. Among them, ferric acid, permanganic acid and chromic acid are more preferred, and permanganic acid is even more preferred.

In some embodiments, the composite metal oxide includes monovalent or divalent metal elements other than transition metal elements, and transition metal elements in the fourth period of the periodic table are used as the composite metal oxide. Preferred examples of monovalent or divalent metal elements include Na, K, Mg and Ca. Among them, Na and K are more preferred. Preferred examples of transition metal elements in the fourth period of the periodic table include Fe, Mn, Cr, V and Ti. Among them, Fe, Mn and Cr are more preferred, and Mn is even more preferred. Composite metal oxides can effectively reduce surface hardness and cause surface embrittlement of materials with high hardness such as polycrystalline SiC.

In some embodiments, the amount of oxidizing agent affects the properties of the grinding composition, such as RR, Ra, and Rz. The amount of oxidizing agent in the grinding composition is from about 0.01 wt% to about 5.0 wt%, from about 0.05 wt% to about 4.5 wt%, from about 0.1 wt% to about 4.0 wt%, from 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 oxidizing agent is present in the grinding composition in an amount 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 entire composition. In some embodiments, the amount of oxidizing agent in the grinding composition may range from 1.5 wt% to 3.5 wt%. In some embodiments, the amount of permanganate in the grinding composition may range from 1.5 wt% to 3.5 wt%.

In one embodiment, the grinding composition has an oxidation-reduction potential ORPx that is 100 mV or more higher than the oxidation-reduction potential ORPy of the material to be ground. In some embodiments, the grinding 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. In some embodiments, the redox potential ORPx of the grinding composition is about 150 mV or greater, 200 mV or greater, 250 mV or greater, 300 mV or greater, 350 mV or greater, 350 mV or greater than the redox potential ORPy of the material to be ground. mV or greater, 400 mV or greater, 450 mV or greater, 500 mV or greater, 550 mV or greater, or about 600 mV or greater. In one embodiment, the redox potential ORPx of the grinding composition is 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, approximately 700 mV to approximately 1200 mV, approximately 800 mV to approximately 1100 mV, or approximately 800 mV to approximately 1,000 mV. That is, the relationship between ORPx (mV) and ORPy (mV) satisfies the following equation (1): ORPx - ORPy ≧100 mV (1). In one embodiment, the redox potential ORPx of the grinding 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 redox potential ORPy of the material to be ground can 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, and about 300 mV at pH 11.0. Approximately 220 mV at pH 12.0, approximately 190 mV at pH 13.0, and approximately 150 mV at pH 14.0.

The oxidation-reduction potential of the grinding compositions and materials to be ground mentioned herein indicates the oxidation-reduction potential value measured at a liquid temperature of 25°C relative to a standard hydrogen electrode. Oxidation-reduction potential can be measured by using Horiba Laqua Act PC110 as the main body of the measuring device and Horiba Laqua 9300-10D as the electrode. 2. Abrasives

The abrasive compositions described herein contain abrasives. The abrasive is usually a metal oxide abrasive, which is preferably selected from the group consisting of silica, alumina, titanium dioxide, zirconium oxide, germanium oxide, ceria and mixtures thereof. In some embodiments, the abrasive is alumina. In another embodiment, the abrasive contains alpha alumina.

The abrasives disclosed herein exhibit suitable isoelectric points. For example, suitable isoelectric points would be those 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 exhibits 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. It should be noted that the abrasives in the examples described below have an isoelectric point of about 5 to 7. In some embodiments, the isoelectric point can be calculated by measuring the zeta potential. The zeta potential [mV] can be measured, for example, by subjecting an object for measuring the zeta potential to ELS-Z2 manufactured by Otsuka Electronics Co., Ltd. using a flow cell at a measurement temperature of 25°C by laser Doppler. The zeta potential is measured using the method (electrophoretic light scattering measurement method) and calculated by analyzing the data obtained by the Smoluchowski equation.

The abrasive can have any suitable particle size. The abrasive may have an average secondary particle size of about 10 nm or larger, about 25 nm or larger, about 50 nm or larger, about 100 nm or larger, or about 500 nm or larger. In some embodiments, the abrasive can have a thickness of about 100 nm or greater, about 200 nm or greater, about 250 nm or greater, about 300 nm or greater, about 350 nm or greater, or about 380 nm or greater. Large average secondary particle size. Alternatively or additionally, the abrasive may have a thickness 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 an average secondary particle size of approximately 25 nm or less. In some embodiments, the abrasive 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 embodiments, the abrasive 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 embodiments, the abrasive 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 can be measured by a particle size analyzer (HORIBA particle size distribution tool). Here, the average particle size means the average secondary particle size.

In addition, abrasives can be further characterized based on specific surface area, which can be obtained using BET technology. In some embodiments, the abrasive comprises about 10 m ² /g to about 250 m ² /g, about 25 m ² /g to about 200 m ² /g, about 50 m ² /g to about 175 m ² /g , a specific surface area in the range of about 75 m ² /g to about 150 m ² /g or about 100 m ² /g to about 150 m ² /g. In some embodiments, the abrasive comprises at least about 25 m ² /g, at least about 50 m ² /g, at least about 75 m ² /g, at least about 100 m ² /g, at least about 125 m ² /g, at least A specific surface area of about 150 m ² /g, at least about 175 m ² /g, at least about 200 m ² /g, or at least about 225 m ² /g.

Additionally, abrasives may be found to have an average density in ^the range of about 0.5 to about 5 g/cm. In some embodiments, the abrasive has 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 An average density of about 3.5 g/cm ³ , at least about 4 g/cm ³ , or at least about 5 g/cm ³ .

Additionally, the abrasive may include crystals having an average crystallite size of no more than about 1 micron. The crystallite size referenced herein may be the same as the grain size referenced, or the average size of the smallest single crystal structure within the grit of the abrasive granular material. In other cases, the average crystallite size may be smaller, such as no greater than about 800 nanometers, no greater than about 500 nanometers, such as no greater than about 300 nanometers, or even no greater than about 200 nanometers. In some embodiments, the average crystallite size may be no greater than about 175 nanometers, no greater than about 160 nanometers, or even no greater than about 150 nanometers. In some embodiments, the abrasive is in the form of aluminum oxide crystals having at least about 0.1 nanometer, at least about 1 nanometer, at least about 5 nanometer, at least about 10 nanometer, at least about 20 nanometer, at least about 30 nanometer. nanometers, at least about 40 nanometers, at least about 50 nanometers, or even at least about 80 nanometers. It is understood that the abrasive may be composed of aluminum oxide crystals having an average crystallite size ranging between any of the minimum and maximum values mentioned above.

In certain other cases, the abrasive may have finer grit sizes, including, for example, no greater than about 1.5 mm, no greater than about 1 mm, no greater than about 500 microns, no greater than about 300 microns, no greater than about 100 microns, An average particle size of no greater than about 50 microns, no greater than about 10 microns, no greater than about 1 micron, no greater than about 0.8 microns, or even no greater than about 0.6 microns. In some embodiments, the abrasive has a finer grit size in the range of about 0.5 microns to about 2 mm, about 1 micron to about 1 mm, or about 1 micron to about 500 microns.

In some embodiments, the amount of abrasive in the grinding 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 grinding composition may 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 in the grinding composition can range from about 0.01 wt% to about 5 wt%, from about 0.01 wt% to about 4.5 wt%, from 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 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 in the grinding composition may range from 1.5 wt% to 3.5 wt%. In some embodiments, the amount of aluminum oxide in the grinding composition may range from 1.5 wt% to 3.5 wt%.

In some embodiments, the alumina abrasive has alpha conversion. As used herein, the term "alpha conversion" refers to the conversion of an alpha aluminum precursor to alpha alumina. In some embodiments, the alpha alumina conversion rate may vary. In some embodiments, the alumina abrasive has a thickness of from about 50% to about 100%, from about 55% to about 95%, from about 60% to about 90%, from about 65% to about 85%, or from about 70% to about 80%. Alpha alumina conversion rate within % range. In some embodiments, the abrasive has an alpha conversion of less than about 100%, less than about 90%, or less than about 80%. In some embodiments, the abrasive has an alpha conversion of at least about 50%, about 55%, about 60%, about 65%, or at least about 70%. In this specification, the α conversion rate is also referred to as the α conversion rate. As the alpha conversion rate, a value obtained from the cumulative intensity of the diffraction line peak (2θ=57.5°) unique to alpha-alumina in the X-ray diffraction spectrum can be used. More specifically, the alpha conversion rate and crystallite size of alumina can be measured by X-ray diffraction measurement under the following measurement conditions; Equipment: Powder X-ray diffractometer Ultima IV manufactured by Rigaku Corporation X-ray generation voltage: 40 kV Radiation: Cu-Kα1 ray Current: 10 mA Scanning speed: 10°/min Measurement steps: 0.01° The alpha conversion rate can be calculated based on the cumulative intensity of the diffraction line peak (2θ=57.5°) unique to alpha-alumina. In addition, the crystallite size can be calculated using the powder X-ray diffraction pattern comprehensive analysis software JADE (automatically calculated by Scherrer equation, manufactured by MDI). 3. PH adjuster

The grinding composition may contain at least one pH adjuster to control pH. In some embodiments, the pH adjuster is a basic compound (alkaline pH adjuster). The basic compound may be appropriately selected from various basic compounds having the function of raising the pH of the grinding composition in which the compound is dissolved. For example, inorganic alkaline compounds such as alkali metal hydroxides, alkaline earth metal hydroxides, various carbonates, bicarbonates, and the like may be used. Such basic compounds may be used alone or in combination of two or more types thereof.

Specific examples of alkali metal hydroxides include potassium hydroxide, sodium hydroxide, ammonium hydroxide and the like. Specific examples of carbonates and bicarbonates include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate and similar salts.

In alternative embodiments, the pH adjusting agent may be a mixture of acidic and basic reagents (such as a buffer). In such embodiments, the choice of acid is not particularly limited, provided that the acid is strong enough to adjust the pH of the grinding composition of the present invention. In some embodiments, the acidic reagent can be an inorganic acid or an organic acid. By way of example and without limitation, such inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid and phosphoric acid.

By way of example and without limitation, such organic acids include formic acid, acetic acid, chloroacetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, N-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric 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-furancarboxylic acid , 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic 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.

In an alternative embodiment, the pH adjusting agent may be a buffer containing phosphates, acetates, borates, sulfonates, carboxylates, and the like.

The amount of pH adjuster can vary and is generally an amount sufficient to achieve and/or maintain the desired pH of the grinding composition (eg, within the ranges set forth herein).

In one embodiment, the pH of the grinding composition is adjusted to 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 The range is from 11.0 to about 13.0, from about 11.5 to about 13.0, from about 12.0 to about 13.0, or from about 12.5 to about 13.0. In one embodiment, the pH of the grinding composition can be adjusted to a range of 9 to 10.

In one embodiment, the pH of the grinding 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 grinding vehicle or grinding 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.

In some embodiments, the pH of the grinding 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, wherein the pH is no less than about 8. In some embodiments, the pH of the grinding composition has a pH greater than 8.

In some embodiments, the pH of the grinding 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.

pH adjusters can be present in a specific concentration range regardless of pH. For example, in some embodiments, the amount of pH adjuster ranges from about 0.0001 wt% to about 1 wt%, from about 0.005 wt% to about 0.5 wt%, or from about 0.001 wt% to about 0.1 wt%. In alternative embodiments, the amount of pH adjuster ranges from about 0.0001 wt% to about 0.0010 wt%, from about 0.0003 wt% to about 0.0009 wt%, or from about 0.0005 wt% to about 0.0008 wt%. In alternative embodiments, the amount of pH adjusting agent ranges from about 0.0009 wt% to about 0.0040 wt% or from about 0.0010 wt% to about 0.0030 wt%. In further alternative embodiments, the pH adjusting agent ranges from about 0.001 wt% to about 0.01 wt%. In some embodiments, the pH adjuster is present in an amount of at least about 0.0001 wt%, at least about 0.0005 wt%, at least about 0.001 wt%, at least about 0.005 wt%, at least about 0.01 wt%, at least about 0.025 wt%, at least about present in an amount of 0.05 wt%, at least about 0.075 wt%, or at least about 0.1 wt%. In some embodiments, the pH adjusting agent is present in an amount of less than about 0.01 wt%, less than about 0.005 wt%, less than about 0.001 wt%, or less than about 0.0005 wt%. In some embodiments, the pH adjuster is present at about 0.0001 wt%, about 0.00025 wt%, about 0.0005 wt%, about 0.0006 wt%, about 0.0007 wt%, about 0.0008 wt%, about 0.0009 wt%, about 0.001 wt%, Present in an amount of about 0.005 wt%, about 0.0075 wt%, about 0.01 wt%, about 0.025 wt%, or about 0.05 wt%.

However, the grinding composition must not use too much pH adjuster since the amount of ions will have a negative impact on the selectivity ratio. This also limits the type of pH adjuster. 4. Water

In some embodiments, the abrasive compositions disclosed herein contain a carrier, medium, or vehicle. In one embodiment, the carrier, medium or vehicle is water. Ion exchange water (deionized water), pure water, ultrapure water, distilled water and the like can be used as the water. To reduce the amount of unwanted components present in water, water purity can be increased by operations such as removal of impurity ions with ion exchange resins, removal of contaminants with filters, and/or distillation.

In some embodiments, the water is relatively free of impurities. In 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%, based on the total weight of water. 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 impurities.

The amount of water in the grinding composition can vary. In some embodiments, water is present in at least about 50 wt%, at least about 60 wt%, at least about 70 wt%, at least about 80 wt%, at least about 90 wt%, at least about 92 wt%, at least about 94 wt%, Present in an amount of at least about 96 wt% or at least about 98 wt%.

Grinding compositions containing any of the above-described carriers, media or vehicles will be in the form of a slurry or dispersion. In one embodiment, the temperature of the grinding composition can be adjusted to 5 to 30°C, 6 to 20°C, or 7 to 13°C. 5. Additional ingredients

In one embodiment, the grinding compositions disclosed herein may contain additional components such as corrosion inhibitors, carbohydrates, chelating agents, biocides, surfactants, or co-solvents. Additionally or alternatively, the compositions disclosed herein may include other additives as those skilled in the art will appreciate.

In another embodiment, additional components may include corrosion inhibitors. Non-limiting examples of corrosion inhibitors may include 2-methyl-3-butyn-2-ol, 3-methyl-2pyrazolin-5-one, 8-hydroxyquinoline, and dicyanodiamine, benzene Triazole 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 corrosion inhibitor in the abrasive composition may range from about 0.0005 wt% to 0.25 wt%, preferably from 0.0025 wt% to 0.15 wt%, and more preferably from 0.05 wt% to 0.1 wt%.

In an alternative embodiment, the abrasive composition does not contain corrosion inhibitors. As used herein, the term "corrosion inhibitor-free" means that the abrasive composition does not contain compounds known in the art to be used as corrosion inhibitors.

In one embodiment, additional components may include carbohydrates. Carbohydrates include sugars, and in some embodiments, the sugars are polysaccharides known as pullulan. The polysaccharide pullulan contains maltotriose units, which consist of three α-1,4-linked glucose molecules that are further linked by α-1,6-linkages.

In an alternative embodiment, the grinding composition contains no carbohydrates. As used herein, the term "carbohydrate-free" means that the grinding composition does not contain compounds known in the art as carbohydrates.

In another embodiment, additional components may include chelating agents. 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 , nitrotriacetic acid, iminodiacetic acid, ethylenediamine, CDTA and EDTA.

In an alternative embodiment, the abrasive composition does not contain chelating agents. As used herein, the term "chelating agent-free" means that the grinding composition does not contain compounds known in the art as chelating agents. 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, iminotriacetic acid, Acetic acid, ethylenediamine, CDTA and EDTA.

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, alkylbenzyldimethylchloride Ammonium and alkylbenzyldimethylammonium hydroxides, wherein the alkyl chain ranges from 1 to about 20 carbon atoms. More specific examples of chlorine compounds include, but are not limited to, sodium chlorite and sodium hypochlorite. Additional examples of biocides include biguanides, aldehydes, ethylene oxide, isothiazolinones, iodine-bearing compounds, the KATHON (trademark) and NEOLENE (trademark) product lines available from Dow Chemicals, and Preventol available from Lanxess (trademark) series. The amount of biocide used in the abrasive composition may 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%.

In another embodiment, additional components may include surfactants. Surfactants can be anionic, cationic, nonionic or zwitterionic and can increase the lubricity of the vehicle or composition. Non-limiting examples of surfactants are lauryl sulfate, sodium or potassium salts, lauryl sulfate, secondary alkanesulfonates, alcohol ethoxides, acetylene glycol surfactants, quaternary ammonium Mainly surfactants, amphoteric surfactants (such as betaine and surfactants mainly based on amino acid derivatives) and any combination thereof. Examples of suitable commercially available surfactants include the TRITON ^™ , Tergitol ^™ , DOWFAX ^™ series of surfactants manufactured by Dow Chemicals, and SURFYNOL ^™ , DYNOL ^™ , Zetasperse ^™ , Nonidet ^™ and Tomadol ^™ manufactured by Air Products and Chemicals Various surfactants in the surfactant series. Surfactants Suitable surfactants may also include polymers containing ethylene oxide (EO) and propylene oxide (PO) groups. An example of an EO-PO polymer is Tetronic ^™ 90R4 from BASF Chemicals. An example of an acetylenic diol surfactant is Dynol ^™ 607 from Air Products and Chemicals. The amount of surfactant used in the grinding composition may 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%.

In another embodiment, the additional component may include another solvent, referred to as 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. The co-solvent can be used in various amounts, preferably from a low limit of about 0.0001, 0.001, 0.01, 0.1, 0.5, 1, 5 or 10 (wt%) to about 0.001, 0.01, 0.1, 1, 5, 10, 15, 20, 25 or 35 (wt%) upper limit.

Accordingly, as described herein, in some embodiments, abrasive compositions include an oxidizing agent and an abrasive, wherein the oxidizing agent includes a complex metal oxide, the abrasive includes alumina, and the pH of the composition is about 8 or more. big.

The grinding composition as in any of the above embodiments, wherein the oxidizing agent includes potassium permanganate.

The abrasive composition as in any of the above embodiments, wherein the abrasive includes alpha-alumina.

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

The grinding composition in any of the above embodiments, wherein the oxidizing agent is potassium permanganate and the grinding agent is aluminum oxide.

The grinding composition as in any of the above embodiments, wherein the pH is adjusted by a pH adjuster such as potassium hydroxide.

The grinding composition of any of the above embodiments, wherein the oxidizing agent is present in an amount of about 1.5 wt% to about 3.5 wt%.

The abrasive composition as in any of the above embodiments, wherein the abrasive is present in an amount of about 1.5 wt% to about 3.5 wt%.

The grinding composition of 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%.

The abrasive composition of any of the above embodiments, wherein the abrasive is alumina and is present in an amount of about 1.5 wt% to about 3.5 wt%.

The grinding 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 Exists in wt% amount.

The grinding composition as in any one of the above embodiments, wherein the pH is at least 9.

A grinding composition as in any of the above embodiments, wherein the pH is 10 or less.

The grinding composition as in any of the above embodiments further includes a carrier (such as water).

The grinding composition in any of the above embodiments is in the form of slurry. C. Methods of using abrasive compositions

The abrasive compositions described herein may be used to abrade any suitable substrate comprising polycrystalline SiC. In some embodiments, the substrate includes at least one polycrystalline SiC layer. In some embodiments, at least one layer comprising polycrystalline SiC is on the surface of the substrate, ie, the top layer of the substrate. The surface containing polycrystalline SiC may be in the form of a wafer or may be in the form of a thin (or thick) film.

Silicon carbide used in semiconductors can be single crystal or polycrystalline, where examples of such polytypes are cubic (such as 3C silicon carbide) or non-cubic (such as 4H silicon carbide, 6H silicon carbide) or a mixture of polytypes ( That is polycrystalline SiC). The advantage of using polycrystalline SiC is to reduce the cost of the substrate. Some outstanding features of polycrystalline SiC are that it generally does not have the same polarity (Si/C surface) as monocrystalline 4H-SiC, its color is black, and it is opaque.

An additional characteristic of polycrystalline SiC is that since it is composed of multiple polytypes, such as 4H, 3C, and various other polytype crystals, there may be voids (vacancies) at the grain boundaries. The different polytypes in polycrystalline SiC make crystallinity challenging, and polycrystalline SiC varies widely. In addition, the density of polycrystalline SiC is less than 3.21 g/cm ³ of 4H-SiC. The density of polycrystalline SiC may be 3.20 g/ ^cm or less, 3.19 g/cm ^or less, 3.18 g/cm ^or less, ^3.17 g/cm or less, or ^3.16 g/cm or less. Small. In addition, the density of polycrystalline SiC may be 3.10 g/cm ³ or greater, 3.15 g/cm ³ or greater, 3.16 g/cm ³ or greater, 3.17 g/cm ³ or greater, 3.18 g/cm ³ or greater, 3.19 g/ ^cm3 or greater, or 3.20 g/ ^cm3 or greater. Because of these and other characteristics, it is difficult to achieve high removal rates and required smoothness of polycrystalline SiC during CMP, which increases production time and associated costs. Accordingly, it is an object of the present invention to provide a method for grinding polycrystalline SiC that provides a high removal rate of polycrystalline SiC with a desired smoothness.

Grinding materials containing polycrystalline SiC can benefit a variety of applications such as, but not limited to, flat panel displays, integrated circuits, memory or hard disks, metals, interlayer dielectric (ILD) devices, semiconductors, microelectromechanical systems, iron Electrical body and magnetic tape.

Accordingly, in some embodiments, the subject matter disclosed herein relates to a method of grinding a substrate containing polycrystalline SiC using the grinding composition disclosed herein. In some embodiments, a method of grinding a substrate comprising polycrystalline SiC includes: (a) providing a substrate comprising polycrystalline SiC; (b) providing a grinding composition described herein; (c) applying the grinding composition to the substrate and (d) polishing at least a portion of the substrate with the polishing composition to polish the substrate.

In some embodiments, the equipment used in the grinding methods disclosed herein is chemical mechanical polishing (CMP) equipment, but the methods disclosed should not be limited thereto. Typically, the apparatus includes a pressure plate that is in motion during use and has a speed resulting from orbital, linear or circular motion; an abrasive pad that is in contact with the pressure plate and moves with the pressure plate when in motion; and a carrier that is held in place to be borrowed. A substrate that is polished by contacting the surface of a polishing pad and moving relative to that surface. Polishing of the substrate is performed by placing the substrate in contact with a polishing pad and a polishing composition (the polishing composition is typically disposed between the substrate and the polishing pad), wherein the polishing pad moves relative to the substrate to polish at least a portion of the substrate to Grind the substrate. The grinding endpoint can then be determined by monitoring the weight of the polycrystalline SiC-containing substrate, which is used to calculate the amount of polycrystalline SiC removed from the substrate. Such techniques are well known in the art.

The polishing pad used here is not particularly limited. For example, any abrasive pad may be used, including non-woven types, suede types, polyurethane types including hard foam types and soft foam types, abrasive-containing types, abrasive-free types, and the like.

Grinding means removing at least a portion of a surface to grind the surface. Grinding may be performed to provide a surface with reduced surface roughness by removing grooves, crates, dimples and the like, but may also be performed to introduce or restore surface geometry characterized by the intersection of flat sections.

Polycrystalline SiC may be removed at any suitable rate to achieve polishing of the substrate in the polishing methods disclosed herein. In some embodiments, the removal rate (RR) of the polishing composition used in the disclosed polishing methods is from about 1 μm/h to about 10 μm/h, from about 2 μm/h to about 8 μm/h, In the range of about 3 μm/h to about 7 μm/h, about 4 μm/h to about 7 μm/h, about 4.5 μm/h to about 6.5 μm/h, and about 5.0 μm/h to about 6.0 μm/h. In some embodiments, the RR ranges from about 6.0 μm/h to about 7.0 μm/h. In some embodiments, the RR is at least about 1.0 μm/h, about 2.0 μm/h, about 3.0 μm/h, about 4.0 μm/h, about 4.5 μm/h, about 5.0 μm/h, about 5.5 μm/h. , about 6.0 μm/h or about 7.0 μm/h. In some embodiments, the RR is less than about 10.0 μm/h, about 9.0 μm/h, about 8.0 μm/h, about 7.0 μm/h, about 6.5 μm/h, about 5.0 μm/h, about 4.5 μm/h. , about 4.0 μm/h, about 3.0 μm/h, about 2.0 μm/h or about 1.0 μm/h.

In some embodiments, the grinding methods disclosed herein employ grinding compositions having a specific average roughness index (Ra). In some embodiments, the Ra of the grinding composition is from about 0.01 nm to about 1.50 nm, from about 0.01 nm to about 1.20 nm, from about 0.10 nm to about 1.2 nm, from about 0.25 nm to about 1.20 nm, from 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 grinding composition used in the disclosed grinding method has an Ra of 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.

In some embodiments, the grinding methods disclosed herein employ grinding compositions having a specific average roughness depth (Rz). In some embodiments, the Rz of the grinding composition is from about 1 nm to about 20 nm, from about 5 nm to about 15 nm, from about 6 nm to about 12 nm, from about 7 nm to about 10 nm, from about 8 nm to about 10 nm. nm or in the range of about 9 nm to about 10 nm. In some embodiments, the grinding composition has Rz 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, about 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.

In some embodiments, the grinding methods disclosed herein employ any suitable head pressure. In some embodiments, the head pressure of the grinding process 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 a range of about 6 psi to about 8 psi.

In some embodiments, the grinding methods disclosed herein employ any suitable platen rotation speed. In some embodiments, the platen rotation speed of the grinding method is 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 in the range of about 110 rpm to about 130 rpm.

In some embodiments, the grinding methods disclosed herein employ any suitable head rotation speed. In some embodiments, the head rotation speed of the grinding method is from about 90 rpm to about 200 rpm, from about 100 rpm to about 190 rpm, from about 110 rpm to about 180 rpm, from about 120 rpm to about 170 rpm, from about 130 rpm to about 170 rpm. About 160 rpm or in the range of about 140 rpm to about 150 rpm.

In some embodiments, the grinding methods disclosed herein employ any suitable pressure velocity (PV). In some embodiments, the PV of the grinding method is between about 300 psi*in/second and about 900 psi*in/second, between about 350 psi*in/second and about 850 psi*in/second, and about 400 psi*in/second. to about 800 psi*inch/second or in the range of about 450 psi*inch/second to about 750 psi*inch/second.

Therefore, in some embodiments, methods of using abrasive compositions are described herein, wherein the methods include the steps of: a) providing a polishing composition as disclosed herein (eg, technical solution 1); b) providing a substrate, wherein The substrate includes a layer containing polycrystalline silicon carbide (polycrystalline SiC); and c) grinding the substrate with the grinding composition to provide a ground substrate.

As in any of the above embodiments, the substrate is a semiconductor.

As in any of the above embodiments, wherein the method produces a polycrystalline SiC removal rate in the range of about 4 μm/h to about 7 μm/h.

As in any of the above embodiments, the ground substrate has a roughness index (Ra) of less than about 1.2 nm.

As in any of the above embodiments, wherein the ground substrate has a specific average roughness depth (Rz) of less than about 10 nm.

As in any of the above embodiments, wherein the abrasive composition includes an abrasive having an isoelectric point in the range of about 5 to about 7. The abrasive compositions in the examples described below have isoelectric points in the range of about 5 to about 7.

As in any of the above embodiments, wherein the grinding composition includes a grinding agent that does not contain transition phase alumina.

As in any of the above embodiments, the grinding composition includes an oxidizing agent that is potassium permanganate.

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

As in any of the above embodiments, wherein the grinding composition has a pH in the range of about 9 to about 10. D.Example

The following preparations and examples are given to enable those skilled in the art to more clearly understand and practice the present invention. They should not be considered as limiting the scope of the invention, but are merely illustrative and representative.

In one aspect, methods of preparing abrasive compositions are disclosed. In another aspect, methods of grinding materials using abrasive compositions are disclosed.

Example 1 - Abrasive Evaluation

The average secondary particle size of the alumina abrasive was measured by a laser diffraction/scattering particle size distribution measuring device (LA-950 manufactured by Horiba Corporation) and is shown in Table 1.

[Table 1] Table 1: Abrasive evaluation Average secondary particle size (μm) Alumina A 0.44

Example 2: Measure the removal rate (RR), roughness index (Ra) and average roughness depth (Rz) of the experimental slurry.

Table 2 below shows the grinding equipment used and general settings of the grinding parameters.

[Table 2] Table 2: Grinding/Cleaning inclusions Project Comment Grinding equipment REVASUM 6EC2 -- polishing pad IC1000k groove If appropriate, use a hard pad for shape transfer regulator KINIK 179B -- Common grinding conditions Head pressure (7 psi), platen/head rotation (120/145 rpm) Can show rough PV deviation slurry flow rate 50ml/min Low temperature is better Slurry stirring rate <150rpm -- Grinding time 5 minutes -- Cooler temperature 10℃ Low temperature inhibition rate selectivity pH adjustment HNO ₃ is used for acidic compositions and KOH is used for alkaline compositions. -- *The cooler is a device used to cool the pressure plate. The temperature at the cooler temperature is a value obtained by measuring the pad surface temperature close to the head/substrate during polishing with a radiation thermometer. * Since polycrystalline SiC is polycrystalline, various crystal orientations, Si surfaces and C surfaces are mixed on the ground surface. As the rate selectivity decreases, therefore, the Ra (mn) and Rz (nm) of the polished surface can decrease.

Test conditions/parameters from Table 2: (a) REVSUM 6EC2 is used for single-side grinding of approximately 22-inch diameter platens; (b) Select Rohm and Haas IC1000 k-groove pad, which is a hard polyurethane polishing pad; (c) KINIK 179B is used as a conditioner for the pad, and the conditioning process used lasts about 2 minutes, followed by test grinding with 5 Lbs; (d) The cooler temperature is set to 10°C during the grinding test; (e) Use a slurry flow rate of 50 ml/min; (f) The grinding conditions adopt a head pressure of 7.0 psi, and platen and head speeds of 120 and 145 rpm respectively; and (g) The grinding time is 5 minutes.

[Table 3] Table 3: Wafer evaluation inclusions Project Comment test wafer Test wafer 1: polycrystalline SiC wafer purchased from a conventional supplier. • Nominal Ra < 7 nm • Density = 3.15 g/cm ³ test wafer Test wafer 2: polycrystalline SiC wafer purchased from a conventional supplier. • Nominal Ra < 7 nm • Density = 3.2 g/cm ³ Substrate cleaning Use organic acids and surfactants (Kanto M02, etc.), SPM, DHF and PVA to wipe. Spin rinse dryer. Clean in batches Remove METTLER TOLEDO analytical balance ME204TE weight loss method surface morphology Park SYSTEMS AFM • 10 μm×10μm • 256 pxl×256 pxl • 1 Hz

Table 3 above shows common methods used to evaluate wafer grinding.

Test conditions/parameters: (a) Use a 6-inch polycrystalline SiC test wafer, which can be purchased from a conventional supplier; (b) In test wafer 1, the nominal value of the mirror finish after one-time grinding is Ra less than 7 nm , the density is assumed to be 3.15 g/cm ³ and the SORI is less than 50 μm. In test wafer 2, the nominal value of the primary grinding mirror finish is Ra less than 7 nm, the density is assumed to be 3.2 g/cm ³ , and the SORI is less than 50 μm. It should be noted that "one polishing" means that the supplier has polished test wafer 1 and test wafer 2. (c) Wafers are cleaned by: 1) PVA wipe with organic acid and surfactant (i.e. Kanto chemical CMP-MO ₂ diluted to 10 times with H ₂ O), followed by RCA based cleaning such as 2 ) Sulfuric acid and hydrogen peroxide mixed solution (SPM), and 3) Hydrofluoric acid cleaning; (d) Calculate RR using the weight loss and crystal density before and after CMP after cleaning the substrate; this CMP was performed using the grinding composition of Example 3 (research comparison), and (e) for surface roughness evaluation, the values of Ra and Rz were observed by atomic force microscopy (AFM). The measurement area is 10 microns.

Because polycrystalline SiC has no polarity, the two surfaces are considered to have similar properties when testing RR and Ra/Rz. RR and Ra assessments are performed using one set on each side. First, RR is obtained by weight loss conversion, and then the substrate is cleaned to measure AFM. In addition, one side is evaluated alternately to avoid the effect of residual stress on the grinding surface.

Example 3 - Comparative Study

(Comparative Study 1) Procedure for preparing a polishing composition: Alumina A was provided as an abrasive and mixed in water so that the contents of the entire abrasive (powder) were set to the values shown in Table 4-1. Subsequently, potassium permanganate was added as an oxidizing agent to the contents of the values shown in Table 4-1, followed by stirring at room temperature (25° C.) for 30 minutes, thereby preparing a dispersion liquid. While checking the pH of the dispersion liquid with a pH meter (manufactured by Horiba Co., Ltd.), KOH or HNO ₃ was added as a pH adjuster, thereby adjusting the pH to the values shown in Table 4-1, and thus preparing a grinding composition. Test Wafer 1 was used in Comparative Study 1.

[Table 4-1] Table 4-1 Composition Oxidizing agent(wt%) Powder(wt%) pH value RR(μm/h) Ra(nm) Rz(nm) Comparative example 1_1 4.00 4.0 7.26 7.03 1.76 22.30 Comparative example 1_2 4.00 4.0 2.98 8.30 2.50 28.25 Comparative example 1_3 4.00 1.4 7.93 5.96 2.27 21.76 Comparative example 1_4 4.00 1.4 3.01 7.18 2.60 31.31 Comparative example 1_5 1.40 4.0 6.69 5.72 1.69 21.23 Comparative example 1_6 1.40 4.0 3.00 6.64 2.33 24.89 Comparative example 1_7 1.40 1.4 7.02 4.48 1.38 14.23 Comparative example 1_8 1.40 1.4 3.02 5.55 1.66 14.38 The present invention 1_1 1.50 1.5 9.01 4.96 0.89 9.42 The present invention 1_2 1.50 3.5 8.01 5.52 0.87 9.20 The present invention 1_3 2.00 3.0 8.88 5.65 0.62 8.22 The present invention 1_4 2.95 2.0 9.65 5.67 0.64 7.49 The present invention 1_5 3.50 1.5 9.70 5.98 0.74 8.70 The present invention 1_6 3.50 3.5 9.80 6.98 0.80 9.12 The present invention 1_7 2.95 2.0 11.02 6.69 1.08 9.88 The present invention 1_8 3.5 3.5 11.10 6.92 0.93 9.82 *The powder is aluminum oxide A.

According to the polishing composition according to an aspect of the present invention, when polishing the test wafer 1 with low density, Ra and Rz can be reduced while RR remains high. Because the possibility of pits and grains is higher in wafers with low density, RR tends to be higher and Ra and Rz tend to decrease when grinding this wafer. Therefore, abrasive compositions that can reduce Ra and Rz while keeping RR high can be used for wafers with low density. On the other hand, in Comparative Examples 1 to 6 and 8, RR was high, but Ra and Rz could not be sufficiently reduced. In addition, in Comparative Example 7, RR was low, and Ra and Rz could not be sufficiently reduced.

(Comparative Study 2) Steps for preparing a polishing composition: Alumina A was provided as an abrasive and mixed in water so that the contents of the entire abrasive (powder) were set to the values shown in Table 4-2. Subsequently, potassium permanganate was added as an oxidizing agent to the contents of the values shown in Table 4-2, followed by stirring at room temperature (25° C.) for 30 minutes, thereby preparing a dispersion liquid. While checking the pH of the dispersion liquid with a pH meter (manufactured by Horiba Co., Ltd.), KOH or HNO ₃ was added as a pH adjuster, thereby adjusting the pH to the values shown in Table 4-2, and thus preparing a grinding composition. Test Wafer 2 was used in Comparative Study 2.

[Table 4-2] Table 4-2 Composition Oxidizing agent(wt%) Powder(wt%) pH value RR(μm/h) Ra(nm) Rz(nm) Comparative example 2_1 2.00 3.0 3.00 6.59 1.95 21.69 Comparative example 2_2 2.95 2.0 3.00 5.88 1.46 16.16 Comparative example 2_3 2.00 5.0 11.21 2.99 0.27 3.63 Comparative example 2_4 3.50 5.0 11.22 3.25 0.32 9.74 Comparative example 2_5 1.40 3.5 11.24 2.67 0.34 8.80 Comparative example 2_6 4.00 1.5 11.20 2.82 0.62 6.58 The present invention 2_1 2.95 2.0 9.58 3.64 0.58 7.26 The present invention 2_2 1.50 1.5 9.82 3.44 0.75 12.92 The present invention 2_3 1.50 3.5 9.58 3.34 0.66 6.47 The present invention 2_4 3.50 3.5 9.78 4.85 0.50 8.95 The present invention 2_5 2.00 3.0 9.67 4.15 0.72 9.58 The present invention 2_6 2.95 2.0 9.53 3.70 0.52 6.59 *The powder is aluminum oxide A.

According to the polishing composition according to an aspect of the present invention, when polishing the test wafer 2 with high density, RR can be improved while suppressing increases in Ra and Rz. Because the performance of a high-density wafer is close to that of a single-crystal wafer, when grinding this wafer, Ra and Rz are lower, but there is little improvement in RR. Therefore, as described above, abrasive compositions that can improve RR while suppressing increases in Ra and Rz can be used for wafers with high density. On the other hand, in Comparative Examples 9 and 10, RR was high, but Ra and Rz were reduced. In addition, in Comparative Examples 11 to 14, Ra and Rz were suppressed to be low, but the value of RR was low.

In some embodiments, polycrystalline SiC has a density of 3.18 g/cm or ^greater . In some embodiments, polycrystalline SiC has a density of less than 3.18 g/cm ³ . In some embodiments, the content of both oxidizing agent and abrasive in the grinding composition is preferably greater than 1.5 wt%. Example 4: Relationship between Oxidation Reduction Potential ORP and pH of Grinding Compositions Each of the grinding compositions of Inventions 1, 2, 5 and 6 were prepared and the pH was adjusted to that described in the table below using _HNO3 pH in order to adjust the pH to the acidic side, and KOH was used in order to adjust the pH to the alkaline side. Subsequently, the oxidation-reduction potential ORP at each pH was measured. [Table 5-1] Table 5 KMnO ₄ : 1.5 wt%/Alumina: 3.5 wt% pH (nominal) pH (actual) ORP(mV) 12 12.00 516 11 11.01 562 10 9.97 590 9 8.94 656 8 8.00 723 7(as is) 6.82 769 6 6.21 816 Table 5-2] Table 5 (continued) KMnO ₄ : 1.5 wt% / Aluminum oxide: 1.5 wt% pH (nominal) pH (actual) ORP(mV) 12 12.00 543 11 10.99 590 10 9.98 620 9 8.93 676 8 8.50 699 7(as is) 7.08 781 6 6.29 840 [Table 5-3] Table 5 (continued) KMnO ₄ : 3.5 wt%/Alumina: 1.5 wt% pH (nominal) pH (actual) ORP(mV) 12 12.00 559 11 11.00 602 10 9.92 666 9 9.07 691 8 8.29 722 7(as is) 7.68 748 6 6.23 850 [Table 5-4] Table 5 (continued) KMnO ₄ : 3.5 wt% / Aluminum oxide: 3.5 wt% pH (nominal) pH (actual) ORP(mV) 12 11.99 536 11 11.00 579 10 9.96 627 9 8.98 671 8 8.02 738 7(as is) 7.03 791 6 6.28 854

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 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 illustrative only, with a true scope and spirit of the invention being indicated by the following claims. The present invention includes the following aspects and forms. 1. A polishing composition comprising an oxidant, an abrasive and water, the oxidant being permanganate present in an amount of about 1.5 wt% to about 3.5 wt%; and the abrasive being present in an amount of about 1.5 wt% to about 3.5 Alumina is present in an amount of wt%; wherein the grinding composition has a pH greater than about 8. 2. The abrasive composition of item 1, wherein the abrasive has an isoelectric point in the range of about 5 to about 7. 3. The grinding composition of item 1 or 2, wherein the oxidizing agent is potassium permanganate. 4. The grinding composition of any one of items 1 to 3, wherein the grinding composition further comprises a pH adjuster present in an amount of less than about 0.001 wt%. 5. The grinding composition of item 4, wherein the pH adjuster is an alkaline pH adjuster. 6. The grinding composition of item 5, wherein the pH adjuster is potassium hydroxide. 7. The grinding composition of any one of items 1 to 6, wherein the pH is in the range of about 9 to about 10. 8. The polishing composition according to any one of items 1 to 7, wherein the polishing composition has a polycrystalline SiC removal rate of about 4 μm/h to about 7 μm/h. 9. A method for grinding a substrate containing polycrystalline silicon carbide, the method comprising the following steps: a) providing a grinding composition as in any one of items 1 to 8; b) providing a substrate, wherein the substrate contains a layer of polycrystalline silicon carbide (polycrystalline SiC); and c) grinding the substrate with the grinding composition to provide a ground substrate. 10. The method of item 9, wherein the substrate is a semiconductor. 11. The method of item 9 or 10, wherein the method produces a polycrystalline SiC removal rate in the range of about 4 μm/h to about 7 μm/h. 12. The method of any one of items 9 to 11, wherein the ground substrate has a roughness index (Ra) of less than about 1.2 nm. 13. The method of any one of items 9 to 12, wherein the ground substrate has a specific average roughness depth (Rz) of less than about 13 nm. 14. The method of any one of items 9 to 13, wherein the abrasive composition includes an abrasive having an isoelectric point in the range of about 5 to about 7. 15. The method of any one of items 9 to 14, wherein the grinding composition includes an oxidizing agent that is potassium permanganate. 16. The method of any one of items 9 to 15, wherein the grinding composition has a pH in the range of about 9 to about 10. This application is based on U.S. Provisional Patent Application No. 63/288039 filed on December 10, 2021, the disclosure content of which is incorporated herein by reference in its entirety.

[Fig. 1] Fig. 1 is a graph showing changes in surface morphology Ra/Rz with pH. This figure is of test wafer 1. [Figure 2] Figure 2 is a graph showing changes in removal rate and surface morphology Ra with the concentration of potassium permanganate (KMnO ₄ ). This figure is of test wafer 1. [Fig. 3] Fig. 3 is a graph showing changes in removal rate and surface morphology Ra depending on the concentration of alumina powder. This figure is of test wafer 1. [Fig. 4] Fig. 4 is a graph showing changes in surface morphology Ra/Rz with pH. This figure is of test wafer 2. [Fig. 5] Fig. 5 is a graph showing changes in removal rate and surface morphology Ra with the concentration of potassium permanganate ( _KMnO4 ). This figure is of test wafer 2. [Fig. 6] Fig. 6 is a graph showing changes in removal rate and surface morphology Ra depending on the concentration of alumina powder. This figure is of test wafer 2. [Fig. 7] Fig. 7 is a graph showing the relationship between the oxidation reduction potential ORP and the pH of the polishing composition.

Claims (16)

A grinding composition comprising an oxidizing agent, an abrasive and water, wherein The oxidizing agent is permanganate present in an amount from about 1.5 wt% to about 3.5 wt%; and The abrasive is alumina present in an amount from about 1.5 wt% to about 3.5 wt%; wherein the abrasive composition has a pH greater than about 8. The abrasive composition of claim 1, wherein the abrasive has an isoelectric point in the range of about 5 to about 7. The grinding composition of claim 1, wherein the oxidizing agent is potassium permanganate. The grinding composition of claim 1, wherein the grinding composition further comprises a pH adjuster present in an amount less than about 0.001 wt%. The grinding composition of claim 4, wherein the pH adjuster is an alkaline pH adjuster. The grinding composition of claim 5, wherein the pH adjuster is potassium hydroxide. The grinding composition of claim 1, wherein the pH is in the range of about 9 to about 10. The polishing composition of claim 1, wherein the polishing composition has a polycrystalline SiC removal rate of about 4 μm/h to about 7 μm/h. A method for grinding a substrate containing polycrystalline silicon carbide, the method includes the following steps: a) Provide the abrasive composition as claimed in claim 1; b) providing a substrate, wherein the substrate includes a layer containing polycrystalline silicon carbide (polycrystalline SiC); and c) Polishing the substrate with the polishing composition to provide a polished substrate. The method of claim 9, wherein the substrate is a semiconductor. The method of claim 9, wherein the method produces a polycrystalline SiC removal rate in the range of about 4 μm/h to about 7 μm/h. The method of claim 9, wherein the ground substrate has a roughness index (Ra) of less than about 1.2 nm. The method of claim 9, wherein the ground substrate has a specific average roughness depth (Rz) of less than about 13 nm. The method of claim 9, wherein the abrasive composition includes an abrasive having an isoelectric point in the range of about 5 to about 7. The method of claim 9, wherein the grinding composition includes an oxidizing agent that is potassium permanganate. The method of claim 9, wherein the grinding composition has a pH in the range of about 9 to about 10.