Titanium oxide-based chemical mechanical polishing composition for highly boron doped silicon films

Abstract

The present invention provides a chemical mechanical polishing composition comprising: (a) a titanium oxide abrasive; (b) an oxidizing agent; and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less. The invention also provides a method for chemical mechanical polishing of a substrate, in particular a substrate comprising a boron-doped polycrystalline silicon layer on a surface of the substrate, using the composition.

Description

Background Technology

[0001] Compositions and methods for planarizing or polishing substrate surfaces are well known in the art. Polishing compositions (also known as polishing slurries) typically contain abrasive materials in a liquid carrier and are applied to a surface by contacting the surface with a polishing pad filled with the polishing composition. Typical abrasive materials include silica, cerium oxide, alumina, zirconium oxide, and tin oxide. Polishing compositions are typically used in conjunction with polishing pads (e.g., polishing cloths or polishing discs). As an alternative or supplement to being suspended in the polishing composition, the abrasive material may also be incorporated into the polishing pad.

[0002] During the fabrication of advanced node memory devices, such as dynamic random access memory (DRAM), boron-doped polysilicon or boron-polysilicon alloys are increasingly used as patterning hard masks. Achieving high removal rates for this material via chemical mechanical planarization (CMP) can be challenging due to the high boron content in polysilicon. In addition to the requirement for high removal rates of boron-polysilicon films, some memory device designs also require extremely low removal rates of silicon nitride and / or silicon oxide, which can serve as termination layers in device film stacks. This presents selection requirements during CMP. Furthermore, some memory device designs also require medium to high removal rates of titanium nitride, which is also used in the fabrication of some memory devices. The ability to adjust the removal rates of boron-doped polysilicon and / or titanium nitride relative to silicon oxide and / or silicon nitride would be a desirable feature for polishing compositions and methods useful in device fabrication.

[0003] Therefore, there remains a need in the art for polishing compositions and methods for polishing boron-polycrystalline silicon and titanium nitride layers, wherein boron-polycrystalline silicon and titanium nitride exhibit high removal rates and selectivity. This invention provides such polishing compositions and methods. These and other advantages of the invention, as well as additional inventive features, will become apparent from the description of the invention provided herein. Summary of the Invention

[0004] The present invention provides a chemical mechanical polishing composition comprising: (a) a titanium oxide abrasive; (b) an oxidant; and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less.

[0005] The present invention further provides a method for chemical mechanical polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition comprising: (a) a titanium oxide abrasive; (b) an oxidant; and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the substrate, thereby polishing the substrate. Detailed Implementation

[0006] The present invention provides a chemical mechanical polishing composition comprising: (a) a titanium oxide abrasive; (b) an oxidant; and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less.

[0007] The polishing composition comprises titanium oxide abrasives. As used herein, the terms “abrasive” and “grind” are used interchangeably and may refer to any dispersion of abrasive particles. In other words, the terms “abrasive” and “grind” refer to (i) multiple single types of abrasives or abrasive particles and / or (ii) multiple types of abrasives or abrasive particles.

[0008] Titanium oxide (i.e., titanium dioxide) exists in at least seven polymorphs, four of which are found in nature. The three most common naturally occurring forms of titanium oxide are rutile, anatase, and brookite, with rutile and anatase being the forms usually obtained through synthesis. All forms of titanium oxide have the same empirical formula TiO2, but each has a different crystal structure. The rutile form (“rutile”) is the most thermally stable form of titanium oxide. Rutile has a tetragonal crystal structure, in which Ti-O octahedra share four edges. The anatase form (“anatase”) has a similar tetragonal crystal structure to rutile, except that the Ti-O octahedra share four corners instead of four edges. Anatase spontaneously transforms into the more stable rutile at temperatures above about 915°C. The brookite form (“brookite”) has an orthorhombic crystal structure that spontaneously transforms into rutile at temperatures above about 750°C; this brookite form is the least common of the three common forms and is rarely used commercially.

[0009] Numerous methods for preparing titanium oxides are known in the art. Synthetic methods include gas-phase synthesis and solution-phase synthesis. In the gas-phase synthesis of titanium oxides, a volatile titanium (IV) compound is mixed with water vapor and / or oxygen, and the gas stream is passed through a heated zone to hydrolyze the titanium (IV) compound and produce titanium oxides. The resulting titanium oxides are separated by cooling the gas stream and collecting the particulate titanium oxides. For example, U.S. Patent 4,842,832 teaches a method for synthesizing titanium oxides in which a volatile titanium (IV) compound, such as titanium tetrachloride or titanium tetraalkylol, is evaporated, the vapor is combined with water vapor and / or oxygen and a carrier gas, and the resulting gaseous mixture is heated in the gas phase to a temperature of 250°C to 600°C. The vapor is then cooled to provide spherical titanium oxide particles, which may be amorphous, rutile, anatase, or mixtures thereof. U.S. Patent 4,241,042 describes a method for synthesizing titanium oxides, wherein a liquid aerosol of a hydrolyzable titanium (IV) compound (e.g., titanium tetrachloride or titanium tetraalkylol compound) is contacted with water vapor in a carrier gas and heated, optionally in the presence of a nucleating agent. The vapor is then cooled to provide spherical titanium oxide particles. The spherical particles may be subjected to a heat treatment step at 250°C to 1100°C before or after a recovery step, said heat treatment step increasing the percentage of spherical titanium oxide particles as rutile.

[0010] The synthesis of large quantities of titanium oxide solution phases is also known in the field. Methods that allow the preparation of titanium oxide particles with specific rutile / anatase ratios are well known in the literature. For example, titanium oxide particles are prepared by precipitation from a titanium (IV) salt solution, resulting in a mixture of particles in the form of rutile and anatase, wherein the rutile to anatase ratio depends in part on the specific titanium (IV) compound used as the starting material and the specific reaction conditions (see, for example, Wilska, Acta Chemica Scandinavica, 8:1796-1801 (1954)).

[0011] The phase content of titanium oxides (e.g., the weight ratio of rutile to anatase) can be determined by various techniques. A suitable technique is X-ray diffraction (XRD). Rutile and anatase exhibit X-ray diffraction patterns with different peaks, both individually as pure microcrystals and together in a particular titanium oxide sample. The intensity ratio of the peaks (i.e., lines) in a mixed sample containing both rutile and anatase can be correlated with the concentration of rutile and anatase using a calibration curve obtained by preparing a mixture of rutile and anatase with known amounts of each microcrystal and by obtaining its X-ray diffraction. Although the line intensities of rutile and anatase are not equal with concentration, determining the line intensity ratio of rutile and anatase in a sample containing both rutile and anatase is a useful approximation of the weight ratio of rutile and anatase in the sample. See, for example, Wieska (ibid.) and the references cited therein. Typically, rutile has a useful X-ray diffraction characteristic with a lattice spacing of approximately 3.24 Å, while anatase has a lattice spacing of approximately 3.51 Å.

[0012] Titanium oxide abrasives may comprise any suitable titanium oxide (i.e., titanium dioxide). In some embodiments, the titanium oxide abrasive is a mixture of titanium oxide abrasives comprising rutile titanium oxide and / or anatase titanium oxide. In some embodiments, the X-ray diffraction pattern of the titanium oxide abrasive has an X / Y ratio of about 0.5 or greater, where X is the intensity of a peak in an X-ray diffraction curve representing a lattice spacing of about 3.24 Å and related to the rutile content of the particles, and Y is the intensity of a peak in an X-ray diffraction curve representing a lattice spacing of about 3.51 Å and related to the anatase content of the sample. In other words, most titanium oxide abrasives may be in the form of rutile titanium oxide. In some embodiments, the X / Y ratio is greater than or equal to 0.75 (e.g., about 1 or greater, or about 1.5 or greater, or about 2 or greater, or even about 3 or greater). In some embodiments, the titanium oxide abrasive is substantially composed of rutile (i.e., about 95% or more of the particles are rutile), in which case the X / Y ratio tends to infinity. In one embodiment, the titanium oxide abrasive consists only of rutile (i.e., the intensity of the peak in the X-ray diffraction pattern representing a lattice spacing of approximately 3.51 Å is undetectable). In some embodiments, the titanium oxide abrasive (e.g., rutile titanium oxide abrasive) may contain additional polymorphs (i.e., other than rutile and anatase) present in amounts less than 5%, such as less than 2.5%, less than 1%, less than 0.5%, less than 0.1%, or less than 0.01%. In some embodiments, the titanium oxide abrasive does not contain any detectable amount of additional polymorphs (i.e., other than rutile and anatase).

[0013] Desiredly, the titanium oxide abrasive (e.g., rutile titanium oxide abrasive) is pure or substantially pure titanium oxide; however, small amounts of impurities and dopants may be present in the rutile titanium oxide abrasive. In some embodiments, the titanium oxide is prepared using a method employing dopants, such as tin compounds, to influence the rutile to anatase ratio in the titanium oxide. Therefore, the abrasive may contain small amounts of materials other than the titanium oxide itself (e.g., about 5 wt.% or less, about 4 wt.% or less, about 2 wt.% or less, or about 1 wt.% or less). In some embodiments, the titanium oxide abrasive is substantially pure rutile titanium oxide (i.e., about 99 wt.% or more of titanium oxide and 95% or more of rutile particles).

[0014] Titanium oxide abrasives can be modified (e.g., surface-modified) or unmodified. For example, titanium oxide abrasives can be surface-modified using polyethylene glycol, silanes, or combinations thereof. Suitable polyethylene glycol-based and silane-based compounds for modifying titanium oxide abrasives will be apparent to those skilled in the art. In some embodiments, titanium oxide abrasives are surface-modified using a combination of polyethylene glycol and silanes. For example, the surface of a titanium oxide abrasive can be modified using a compound of the following formula:

[0015] ,

[0016] Where n is from about 2 to about 100, for example, an integer from about 2 to about 50, from about 2 to about 25, or from about 2 to about 20. In some embodiments, the titanium oxide abrasive has limited surface modification or no surface modification.

[0017] Titanium oxide abrasive particles can have any suitable average particle size (i.e., average particle diameter). If the average abrasive particle size is too small, the polishing composition may not exhibit sufficient removal. Conversely, if the average abrasive particle size is too large, the polishing composition may exhibit undesirable polishing performance, such as poor substrate defect levels.

[0018] Therefore, titanium oxide abrasive particles may have an average particle size of about 10 nm or larger, such as about 20 nm or larger, about 25 nm or larger, about 30 nm or larger, about 35 nm or larger, about 40 nm or larger, about 45 nm or larger, or about 50 nm or larger. Alternatively, or additionally, titanium oxide abrasive particles may have an average particle size of about 300 nm or smaller, such as about 250 nm or smaller, about 225 nm or smaller, about 200 nm or smaller, about 175 nm or smaller, about 150 nm or smaller, about 125 nm or smaller, about 100 nm or smaller, about 75 nm or smaller, or about 50 nm or smaller. Therefore, titanium oxide abrasive particles may have an average particle size defined by any two of the foregoing endpoints.

[0019] For example, titanium oxide abrasive particles may have a diameter of about 10 nm to about 300 nm, such as about 10 nm to about 250 nm, about 10 nm to about 225 nm, about 10 nm to about 200 nm, about 10 nm to about 175 nm, about 10 nm to about 150 nm, about 10 nm to about 125 nm, about 10 nm to about 100 nm, about 20 nm to about 300 nm, about 20 nm to about 250 nm, about 20 nm to about 225 nm, about 20 nm to about 200 nm, about 20 nm to about 175 nm, about 20 nm to about 150 nm, about 20 nm to about 125 nm, about 20 nm to about 100 nm, about 30 nm to about 300 nm, about 30 nm to about 250 nm, about 30 nm to about 225 nm, about 30 nm to about 200 nm, about 30 nm to about 175 nm, about 30 nm to about 150 nm, about 30 nm to about 125 nm. The average particle size is approximately 10 nm to 100 nm, approximately 40 nm to 300 nm, approximately 40 nm to 250 nm, approximately 40 nm to 225 nm, approximately 40 nm to 200 nm, approximately 40 nm to 175 nm, approximately 40 nm to 150 nm, approximately 40 nm to 125 nm, approximately 40 nm to 100 nm, approximately 50 nm to 300 nm, approximately 50 nm to 250 nm, approximately 50 nm to 225 nm, approximately 50 nm to 200 nm, approximately 50 nm to 175 nm, approximately 50 nm to 150 nm, approximately 50 nm to 125 nm, or approximately 50 nm to 100 nm. In some embodiments, the titanium oxide abrasive has an average particle size of approximately 10 nm to 300 nm or approximately 50 nm to 150 nm.

[0020] For non-spherical abrasive particles, the particle size is the diameter of the smallest sphere surrounding the particle. The particle size of the abrasive can be measured using any suitable technique (e.g., laser diffraction). Suitable particle size measuring instruments are available, for example, from Malvern Instruments (Malvern, UK). For this purpose, the average particle size listed herein refers to the average particle size of all titanium oxide particles present in the polishing composition. For example, although the average particle sizes of the rutile and anatase particle groups present in the polishing composition will generally not be equal, preferably, the average particle sizes of the rutile and anatase particle groups are respectively and together within the range listed herein.

[0021] Titanium oxide abrasives can be present in the polishing composition in any suitable amount. If the polishing composition of the present invention contains too little abrasive, the composition may not exhibit sufficient removal rate. Conversely, if the polishing composition contains too much abrasive, the polishing composition may exhibit undesirable polishing performance and / or may be uneconomical and / or may lack stability. The polishing composition may contain about 10 wt.% or less of titanium oxide abrasives, such as about 9 wt.% or less, about 8 wt.% or less, about 7 wt.% or less, about 6 wt.% or less, about 5 wt.% or less, about 4 wt.% or less, about 3 wt.% or less, about 2 wt.% or less, about 1 wt.% or less, about 0.9 wt.% or less, about 0.8 wt.% or less, about 0.7 wt.% or less, about 0.6 wt.% or less, or about 0.5 wt.% or less of titanium oxide abrasives. Alternatively, or additionally, the polishing composition may contain about 0.001 wt.% or more of titanium oxide abrasive, such as about 0.005 wt.% or more, about 0.01 wt.% or more, 0.05 wt.% or more, about 0.1 wt.% or more, about 0.2 wt.% or more, about 0.3 wt.% or more, about 0.4 wt.% or more, about 0.5 wt.% or more, or about 1 wt.% or more of titanium oxide abrasive. Therefore, the polishing composition may contain any amount of titanium oxide abrasive defined by any two of the foregoing endpoints as needed.

[0022] For example, in some embodiments, the titanium oxide abrasive may polish about 0.001 wt.% to about 10 wt.% of the composition, such as about 0.001 wt.% to about 8 wt.%, about 0.001 wt.% to about 6 wt.%, about 0.001 wt.% to about 5 wt.%, about 0.001 wt.% to about 4 wt.%, about 0.001 wt.% to about 2 wt.%, about 0.001 wt.% to about 1 wt.%, about 0.001 wt.% to about 0.05 wt.%, about 0.01 wt.% to about 10 wt.%, about 0.01 wt.% to about 8 wt.%, about 0.01 wt.% to about 6 wt.%, about 0.01 wt.% to about 5 wt.%, about 0.01 wt.% to about 4 wt.%, about 0.01 wt.% to about 2 wt.%, about 0.01 wt.% to about 2 wt.%. wt.% to about 1 wt.%, about 0.05 wt.% to about 10 wt.%, about 0.05 wt.% to about 8 wt.%, about 0.05 wt.% to about 6 wt.%, about 0.05 wt.% to about 5 wt.%, about 0.05 wt.% to about 4 wt.%, about 0.05 wt.% to about 2 wt.%, about 0.05 wt.% to about 1 wt.%, about 0.1 wt.% to about 10 wt.%, about 0.1 wt.% to about 8 wt.%, about 0.1 wt.% to about 6 wt.%, about 0.1 wt.% to about 5 wt.%, about 0.1 wt.% to about 4 wt.%, about 0.1 wt.% to about 2 wt.%, about 0.1 wt.% to about 1 wt.%, about 0.5 wt.% to about 10 wt.%, about 0.5 wt.% to about 8 The polishing composition is present in amounts of about 0.001 wt.% to about 10 wt.%, about 0.5 wt.% to about 10 wt.%, about 1 wt.% to about 8 wt.%, about 1 wt.% to about 6 wt.%, about 1 wt.% to about 5 wt.%, about 1 wt.% to about 4 wt.%, or about 1 wt.% to about 2 wt.%. In some embodiments, the polishing composition comprises about 0.025 wt.% to about 5 wt.% of titanium oxide abrasive. In other embodiments, the polishing composition comprises about 0.001 wt.% to about 0.05 wt.% of titanium oxide abrasive.

[0023] Chemical mechanical polishing compositions contain an oxidizing agent. The oxidizing agent can be any suitable compound capable of oxidizing a substrate (e.g., boron-doped polycrystalline silicon, silicon nitride, silicon oxide, or titanium nitride). For example, the oxidizing agent can be selected from potassium persulfate, cerium ammonium nitrate, peroxides (e.g., hydrogen peroxide), periodates (e.g., sodium periodate or potassium periodate), iodates (e.g., sodium iodate, potassium iodate, or ammonium iodate), persulfates (e.g., sodium persulfate, potassium persulfate, or ammonium persulfate), chlorates (e.g., sodium chlorate or potassium chlorate), chromates (e.g., sodium chromate or potassium chromate), permanganates (e.g., sodium permanganate, potassium permanganate, or ammonium permanganate), bromates (e.g., sodium bromate or potassium bromate), perbromates (e.g., sodium perbromate or potassium perbromate), ferrates (e.g., potassium ferrate), perrhenates (e.g., ammonium perrhenate), perruthenates (e.g., tetrapropylammonium perruthenate), and combinations thereof. The oxidizing agent may be in acid form (e.g., persulfate), salt form (e.g., ammonium persulfate), or a mixture thereof. In some embodiments, the oxidizing agent comprises an alkali metal (e.g., sodium or potassium) salt of a peroxide, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof.

[0024] In some embodiments, the oxidant is selected from permanganates (e.g., sodium permanganate, potassium permanganate, or ammonium permanganate), cerium ammonium nitrate, and combinations thereof. In some embodiments, the oxidant is cerium ammonium nitrate. In other embodiments, the oxidant is a permanganate (e.g., sodium permanganate, potassium permanganate, or ammonium permanganate), such as potassium permanganate.

[0025] The polishing composition may contain any suitable amount of oxidant. The polishing composition may contain about 20 wt.% or less of oxidant, such as about 15 wt.% or less, about 10 wt.% or less, about 9 wt.% or less, about 8 wt.% or less, about 7 wt.% or less, about 6 wt.% or less, about 5 wt.% or less, about 4 wt.% or less, about 3 wt.% or less, or about 2 wt.% or less of oxidant. Alternatively, or additionally, the polishing composition may contain about 0.1 wt.% or more of oxidant, such as about 0.5 wt.% or more, about 1 wt.% or more, about 2 wt.% or more, about 3 wt.% or more, about 4 wt.% or more, or about 5 wt.% or more of oxidant. Therefore, the polishing composition may contain any amount of oxidant defined by any two of the foregoing endpoints as needed.

[0026] For example, in some embodiments, the oxidant may be from about 0.1 wt.% to about 20 wt.%, such as about 0.1 wt.% to about 15 wt.%, about 0.1 wt.% to about 10 wt.%, about 0.1 wt.% to about 9 wt.%, about 0.1 wt.% to about 8 wt.%, about 0.1 wt.% to about 7 wt.%, about 0.1 wt.% to about 6 wt.%, about 0.1 wt.% to about 5 wt.%, about 0.1 wt.% to about 4 wt.%, about 0.1 wt.% to about 3 wt.%, about 0.1 wt.% to about 2 wt.%, about 0.5 wt.% to about 20 wt.%, about 0.5 wt.% to about 15 wt.%, about 0.5 wt.% to about 10 wt.%, about 0.5 wt.% to about 9 wt.%, about 0.5 wt.% to about 8 wt.%, about 0.5 wt.% to about 7 wt.%. wt.%, about 0.5 wt.% to about 6 wt.%, about 0.5 wt.% to about 5 wt.%, about 0.5 wt.% to about 4 wt.%, about 0.5 wt.% to about 3 wt.%, about 0.5 wt.% to about 2 wt.%, about 1 wt.% to about 20 wt.%, about 1 wt.% to about 15 wt.%, about 1 wt.% to about 10 wt.%, about 1 wt.% to about 9 wt.%, about 1 wt.% to about 8 wt.%, about 1 wt.% to about 7 wt.%, about 1 wt.% to about 6 wt.%, about 1 wt.% to about 5 wt.%, about 1 wt.% to about 4 wt.%, about 1 wt.% to about 3 wt.%, about 1 wt.% to about 2 wt.%, about 2 wt.% to about 20 wt.%, about 2 wt.% to about 15 wt.%, about 2 wt.% to about 10 wt.%, about 2 The polishing composition is present in amounts of about 9 wt.% to about 9 wt.%, about 2 wt.% to about 8 wt.%, about 2 wt.% to about 7 wt.%, about 2 wt.% to about 6 wt.%, about 2 wt.% to about 5 wt.%, about 2 wt.% to about 4 wt.%, about 2 wt.% to about 3 wt.%, about 3 wt.% to about 20 wt.%, about 3 wt.% to about 15 wt.%, about 3 wt.% to about 10 wt.%, about 3 wt.% to about 9 wt.%, about 3 wt.% to about 8 wt.%, about 3 wt.% to about 7 wt.%, about 3 wt.% to about 6 wt.%, about 3 wt.% to about 5 wt.%, or about 3 wt.% to about 4 wt.%.In some embodiments, the polishing composition comprises at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of an oxidant, at least 2 wt.% (e.g., 2 wt.% to 20 wt.%, 2 wt.% to 10 wt.%, or 2 wt.% to 5 wt.%) of an oxidant, or at least 3 wt.% (e.g., 3 wt.% to 20 wt.%, 3 wt.% to 10 wt.%, or 3 wt.% to 5 wt.%) of an oxidant.

[0027] The polishing composition may contain iron ions, cobalt ions, manganese ions, organic acids, or combinations thereof.

[0028] Iron ions may be provided in the form of any suitable iron salt. A non-limiting example of a suitable iron salt is ferric nitrate. The polishing composition may contain any suitable amount of iron ions. For example, the polishing composition may contain about 0.005 wt.% to about 1 wt.% of iron ions, such as about 0.01 wt.% to about 0.9 wt.%, about 0.02 wt.% to about 0.8 wt.%, about 0.03 wt.% to about 0.6 wt.%, about 0.03 wt.% to about 0.4 wt.%, about 0.03 wt.% to about 0.2 wt.%, or about 0.03 wt.% to about 0.1 wt.%.

[0029] In some embodiments, the polishing composition is substantially free of iron ions. In the context of this invention, "substantially free of iron ions" means that the polishing composition contains about 0.01 wt.% or less of iron ions, such as about 0.005 wt.% or less, about 0.001 wt.% or less, or about 0.0001 wt.% or less of iron ions, or means that iron ions are undetectable in the polishing composition.

[0030] Cobalt ions may be provided in the form of any suitable cobalt salt. A non-limiting example of a suitable cobalt salt is cobalt acetate. The polishing composition may contain any suitable amount of cobalt ions. For example, the polishing composition may contain about 0.005 wt.% to about 1 wt.% of cobalt ions, such as about 0.01 wt.% to about 0.9 wt.%, about 0.02 wt.% to about 0.8 wt.%, about 0.03 wt.% to about 0.6 wt.%, about 0.03 wt.% to about 0.4 wt.%, about 0.03 wt.% to about 0.2 wt.%, or about 0.03 wt.% to about 0.1 wt.%.

[0031] In some embodiments, the polishing composition is substantially free of cobalt ions. In the context of this invention, "substantially free of cobalt ions" means that the polishing composition contains about 0.01 wt.% or less of cobalt ions, such as about 0.005 wt.% or less, about 0.001 wt.% or less, or about 0.0001 wt.% or less of cobalt ions, or means that cobalt ions are undetectable in the polishing composition.

[0032] Manganese ions may be provided in the form of any suitable manganese salt. A non-limiting example of a suitable manganese salt is manganese acetate. The polishing composition may contain any suitable amount of manganese ions. For example, the polishing composition may contain about 0.005 wt.% to about 1 wt.% of manganese ions, such as about 0.01 wt.% to about 0.9 wt.%, about 0.02 wt.% to about 0.8 wt.%, about 0.03 wt.% to about 0.6 wt.%, about 0.03 wt.% to about 0.4 wt.%, about 0.03 wt.% to about 0.2 wt.%, or about 0.03 wt.% to about 0.1 wt.%.

[0033] In some embodiments, the polishing composition is substantially free of manganese ions. In the context of this invention, "substantially free of manganese ions" means that the polishing composition contains about 0.01 wt.% or less of manganese ions, such as about 0.005 wt.% or less, about 0.001 wt.% or less, or about 0.0001 wt.% or less of manganese ions, or means that manganese ions are undetectable in the polishing composition.

[0034] The polishing composition may contain an organic acid. The organic acid may be any suitable organic acid. Non-limiting examples of suitable organic acids include tartaric acid, lactic acid, formic acid, acetic acid, maleic acid, citric acid, L-ascorbic acid, pyridinecarboxylic acid, and malonic acid. In some embodiments, the organic acid is selected from maleic acid, citric acid, L-ascorbic acid, pyridinecarboxylic acid, malonic acid, and combinations thereof.

[0035] The polishing composition may contain any suitable concentration of organic acid. For example, the polishing composition may contain about 1 mM or more of organic acid, such as about 2 mM or more, about 3 mM or more, about 4 mM or more, or about 5 mM or more of organic acid. Alternatively, or additionally, the polishing composition may contain about 100 mM or less of organic acid, such as about 50 mM or less, about 25 mM or less, about 20 mM or less, about 19 mM or less, about 18 mM or less, about 17 mM or less, about 16 mM or less, or about 15 mM or less of organic acid. Therefore, the polishing composition may contain any amount of organic acid defined by any two of the foregoing endpoints. For example, the polishing composition may contain an organic acid of about 1 mM to about 20 mM, such as an organic acid of about 1 mM to about 15 mM, about 2 mM to about 15 mM, about 3 mM to about 15 mM, about 3 mM to about 12 mM, about 1 mM to about 12 mM, or about 1 mM to about 10 mM. In some embodiments, the polishing composition contains an organic acid of about 1 mM to about 100 mM.

[0036] In some embodiments, the polishing composition is substantially free of organic acids. In the context of this invention, "substantially free of organic acids" means that the polishing composition contains about 1 mM or less of an organic acid, such as about 0.5 mM or less, about 1 µM or less, or about 0.5 µM or less, or that organic acids are undetectable in the polishing composition. In some embodiments, the polishing composition is substantially free of iron ions, substantially free of cobalt ions, substantially free of manganese ions, and / or substantially free of organic acids.

[0037] In some embodiments, the polishing composition further comprises a dispersant. The dispersant can be any suitable dispersant. For example, the dispersant can be a nonionic polymer dispersant or anionic polymer dispersant. For example, the dispersant can comprise polyvinyl alcohol (PVA), glycerol, polyethylene glycol (PEG), polypropylene glycol (PPG), polyvinylpyrrolidone (PVP), polyacrylic acid, polymethacrylic acid, ammonium polyacrylate, ammonium polymethacrylic acid, maleic acid polyacrylate, or combinations thereof. In some embodiments, the dispersant comprises polyoxyethylene, such as polyethylene oxide, polypropylene oxide, or combinations thereof.

[0038] The polishing composition may contain any suitable amount of dispersant. The polishing composition may contain about 10 wt.% or less of dispersant, such as about 9 wt.% or less, about 8 wt.% or less, about 7 wt.% or less, about 6 wt.% or less, about 5 wt.% or less, about 4 wt.% or less, about 3 wt.% or less, or about 2 wt.% or less of dispersant. Alternatively, or additionally, the polishing composition may contain about 0.1 wt.% or more of dispersant, such as about 0.5 wt.% or more, about 1 wt.% or more, or about 2 wt.% or more of dispersant. Therefore, the polishing composition may contain any amount of dispersant defined by any two of the foregoing endpoints as needed.

[0039] For example, in some embodiments, the dispersant may be from about 0.1 wt.% to about 10 wt.%, from about 0.1 wt.% to about 9 wt.%, from about 0.1 wt.% to about 8 wt.%, from about 0.1 wt.% to about 7 wt.%, from about 0.1 wt.% to about 6 wt.%, from about 0.1 wt.% to about 5 wt.%, from about 0.1 wt.% to about 4 wt.%, from about 0.1 wt.% to about 3 wt.%, from about 0.1 wt.% to about 2 wt.%, from about 0.5 wt.% to about 10 wt.%, from about 0.5 wt.% to about 9 wt.%, from about 0.5 wt.% to about 8 wt.%, from about 0.5 wt.% to about 7 wt.%, from about 0.5 wt.% to about 6 wt.%, from about 0.5 wt.% to about 5 wt.%, from about 0.5 wt.% to about 4 wt.%, from about 0.5 wt.% to about 3 wt.% The polishing composition is present in amounts of about 0.5 wt.% to about 2 wt.%, about 1 wt.% to about 10 wt.%, about 1 wt.% to about 9 wt.%, about 1 wt.% to about 8 wt.%, about 1 wt.% to about 7 wt.%, about 1 wt.% to about 6 wt.%, about 1 wt.% to about 5 wt.%, about 1 wt.% to about 4 wt.%, about 1 wt.% to about 3 wt.%, about 1 wt.% to about 2 wt.%, about 2 wt.% to about 10 wt.%, about 2 wt.% to about 9 wt.%, about 2 wt.% to about 8 wt.%, about 2 wt.% to about 7 wt.%, about 2 wt.% to about 6 wt.%, about 2 wt.% to about 5 wt.%, about 2 wt.% to about 4 wt.%, or about 2 wt.% to about 3 wt.%. In some embodiments, the polishing composition comprises about 0.1 wt.% to about 4 wt.% of a dispersant, about 0.5 wt.% to about 4 wt.% of a dispersant, about 0.5 wt.% to about 3 wt.% of a dispersant, about 1 wt.% to about 4 wt.% of a dispersant, or about 1 wt.% to about 3 wt.% of a dispersant.

[0040] The polishing composition contains water. The water can be any suitable type of water, and can be, for example, deionized water or distilled water. In some embodiments, the polishing composition may further contain one or more organic solvents in combination with water. For example, the polishing composition may further contain hydroxyl solvents (e.g., methanol or ethanol), ketone solvents, amide solvents, sulfoxide solvents, etc.

[0041] The polishing composition may have any suitable pH. Typically, the polishing composition has a pH of about 7 or less, such as about 6.5 or less, about 6 or less, about 5.5 or less, about 5 or less, about 4.5 or less, or about 4 or less. Alternatively, or additionally, the polishing composition may have a pH of about -2 or greater, such as about -1.5 or greater, about -1 or greater, about -0.5 or greater, about 0 or greater, about 0.5 or greater, about 1 or greater, about 1.5 or greater, or about 2 or greater. Thus, the polishing composition may have a pH defined by any two of the foregoing endpoints.

[0042] For example, the polishing composition may have a pH of about -2 to about 7, such as about -1.5 to about 7, about -1 to about 7, about -0.5 to about 7, about 0 to about 7, about 0.5 to about 7, about 1 to about 7, about 1.5 to about 7, about 2 to about 7, about -2 to about 6.5, about -1.5 to about 6.5, about -1 to about 6.5, about -0.5 to about 6.5, about 0 to about 6.5, about 0.5 to about 6.5, about 1 to about 6.5, about 1.5 to about 6.5, about 2 to about 6.5, about -2 to about 6, about -1.5 to about 6, about -1 to about 6, about -0.5 to about 6, about 0 to about 6, about 0.5 to about 6, about 1 to about 6, about 1.5 to about 6, about 2 to about 6, about -2 to about 5.5, about -1.5 to about 5.5, about -1 to about 5.5, about -0.5 pH values ​​of approximately 5.5, approximately 0 to approximately 5.5, approximately 0.5 to approximately 5.5, approximately 1 to approximately 5.5, approximately 1.5 to approximately 5.5, approximately 2 to approximately 5.5, approximately -2 to approximately 5, approximately -1.5 to approximately 5, approximately -1 to approximately 5, approximately -0.5 to approximately 5, approximately 0 to approximately 5, approximately 0.5 to approximately 5, approximately 1 to approximately 5, approximately 1.5 to approximately 5, approximately 2 to approximately 5, approximately -2 to approximately 4.5, approximately -1.5 to approximately 4.5, approximately -1 to approximately 4.5, approximately -0.5 to approximately 4.5, approximately 0 to approximately 4.5, approximately 0.5 to approximately 4.5, approximately 1 to approximately 4.5, approximately 1.5 to approximately 4.5, approximately 2 to approximately 4.5, approximately -2 to approximately 4, approximately -1.5 to approximately 4, approximately -1 to approximately 4, approximately -0.5 to approximately 4, approximately 0 to approximately 4, approximately 0.5 to approximately 4, approximately 1 to approximately 4, approximately 1.5 to approximately 4, approximately 2 to approximately 4. In some embodiments, the chemical mechanical polishing composition has a pH of about 6 or less. In some embodiments, the polishing composition has a pH of about 5 or less, or about 4 or less. In other embodiments, the polishing composition has a pH of about 0 to about 7 or about 0 to about 4.

[0043] The pH of the polishing composition can be adjusted using any suitable acid or base. Non-limiting examples of suitable acids include nitric acid, sulfuric acid, phosphoric acid, and organic acids such as formic acid and acetic acid. Non-limiting examples of suitable bases include sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

[0044] In some embodiments, the polishing composition further comprises a buffer. The buffer can be any suitable compound capable of buffering (e.g., maintaining) the polishing composition within a specific pH range. For example, the buffer may be selected from ammonium salts, alkali metal salts, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, amino acids, and combinations thereof.

[0045] The chemical mechanical polishing composition optionally further comprises one or more additives. Illustrative additives include regulators, acids (e.g., sulfonic acids), complexing agents, chelating agents, descaling agents, scale inhibitors, and dispersants.

[0046] In some embodiments, the polishing composition further comprises a bioremoving agent. Non-limiting examples of suitable bioremoving agents are isothiazolinone-based bioremoving agents, such as Kordek MLX. TM (DuPont, Wilmington, DE). Polishing compositions may contain any suitable amount of a biodegrading agent. For example, a polishing composition may contain about 0.001 wt.% to about 0.2 wt.% of a biodegrading agent.

[0047] In some embodiments, the present invention provides a chemical mechanical polishing composition comprising, substantially comprising, or comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of a permanganate (e.g., potassium permanganate); and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less.

[0048] In some embodiments, the present invention provides a chemical mechanical polishing composition comprising, substantially comprising, or comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of a permanganate (e.g., potassium permanganate); (c) a dispersant; and (d) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less.

[0049] In some embodiments, the present invention provides a chemical mechanical polishing composition comprising, substantially comprising, or comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of cerium ammonium nitrate; and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less.

[0050] In some embodiments, the present invention provides a chemical mechanical polishing composition comprising, substantially comprising, or comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of cerium ammonium nitrate; (c) a dispersant; and (d) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less.

[0051] Polishing compositions can be produced by any suitable technique, many of which are known to those skilled in the art. Polishing compositions can be prepared by batch or continuous processes. Generally, polishing compositions are prepared by combining the components of a polishing composition. The term "component" as used herein includes individual components (e.g., titanium oxide abrasives, oxidants, optional pH adjusters, and / or any optional additives) and any combination of components (e.g., titanium oxide abrasives, oxidants, optional pH adjusters, and / or any optional additives, etc.).

[0052] For example, a polishing composition may be prepared by the following steps: (i) providing all or part of the liquid carrier; (ii) dispersing the titanium oxide abrasive, oxidant, optional pH adjuster and / or any optional additive using any suitable method for preparing this dispersion; (iii) adjusting the pH of the dispersion as needed; and (iv) optionally adding suitable amounts of any other optional components and / or additives to the mixture.

[0053] Alternatively, the polishing composition may be prepared by the following steps: (i) providing one or more components (e.g., an oxidant, optional pH adjuster, and / or any optional additive) in a titanium oxide abrasive slurry; (ii) providing one or more components (e.g., a liquid carrier, an oxidant, optional pH adjuster, and / or any optional additive) in an additive solution; (iii) combining the titanium oxide abrasive slurry with the additive solution to form a mixture; (iv) optionally adding a suitable amount of any other optional additive to the mixture; and (v) adjusting the pH of the mixture as needed.

[0054] The polishing composition can be provided as a single-package system comprising a titanium oxide abrasive, an oxidant, an optional pH adjuster and / or any optional additive, and water. Alternatively, the polishing composition of the present invention can be provided as a dual-package system comprising a titanium oxide abrasive slurry in a first package and an additive solution in a second package, wherein the titanium oxide abrasive slurry is substantially composed of or consisting of titanium oxide abrasive and water, and wherein the additive solution is substantially composed of or consisting of an oxidant, an optional pH adjuster and / or any optional additive. The dual-package system allows for adjustment of the properties of the polishing composition by varying the blending ratio of the two packages (i.e., the titanium oxide abrasive slurry and the additive solution).

[0055] Various methods can be employed to utilize this dual-package polishing system. For example, the titanium oxide abrasive slurry and additive solution can be delivered to the polishing table via different pipes joined and connected at the supply pipe outlet. The titanium oxide abrasive slurry and additive solution can be mixed shortly before polishing or immediately before, or can be supplied to the polishing table simultaneously. Furthermore, when mixing the two packages, deionized water can be added as needed to adjust the polishing composition and the resulting substrate polishing characteristics.

[0056] Similarly, three, four or more packaging systems can be used in conjunction with the present invention, wherein each of the plurality of containers contains different components of the inventive chemimechanical polishing composition, one or more optional components and / or one or more of the same components in different concentrations.

[0057] To mix components contained in two or more storage devices at or near the point of use to produce a polishing composition, the storage devices typically have one or more flow lines guiding the polishing composition from each storage device to the point of use (e.g., a pressure plate, polishing pad, or substrate surface). As used herein, the term "point of use" refers to the point where the polishing composition is applied to the substrate surface (e.g., the polishing pad or the substrate surface itself). The term "flow line" means a flow path from an individual storage container to the point of use of the component stored therein. Flow lines may each guide directly to the point of use, or two or more flow lines may be combined at any point to form a single flow line guiding to the point of use. Furthermore, any of the flow lines (e.g., individual flow lines or combined flow lines) may first guide to one or more other devices (e.g., pumping devices, measuring devices, mixing devices, etc.) before reaching the point of use of one or more components.

[0058] The components of the polishing composition may be delivered independently to the point of use (e.g., the components are delivered to the substrate surface and then mixed during the polishing process), or one or more of the components may be combined before delivery to the point of use, such as shortly before or immediately before delivery to the point of use. If the components are combined "immediately before delivery to the point of use" within approximately 5 minutes or less before being added to the pressure plate in mixed form, such as approximately 4 minutes or less, approximately 3 minutes or less, approximately 2 minutes or less, approximately 1 minute or less, approximately 45 seconds or less, approximately 30 seconds or less, approximately 10 seconds or less, or simultaneously with delivery at the point of use (e.g., the components are combined at the dispenser), then the components are combined "immediately before delivery to the point of use." Similarly, if the components are combined within 5 m of the point of use, such as within 1 m of the point of use, or even within 10 cm of the point of use (e.g., within 1 cm of the point of use), then the components are also combined "immediately before delivery to the point of use."

[0059] When two or more components of a polishing composition are combined before reaching the point of use, the components can be combined in a flow path and delivered to the point of use without the use of a mixing device. Alternatively, one or more of the flow paths can be directed to a mixing device to facilitate the combination of two or more components. Any suitable mixing device can be used. For example, the mixing device can be a nozzle or orifice through which two or more of the components flow (e.g., a high-pressure nozzle or orifice). Alternatively, the mixing device can be a container-type mixing device comprising: one or more inlets through which two or more components of the polishing slurry are introduced into the mixer; and at least one outlet through which the mixed components exit the mixer to be delivered directly or via other elements of the device (e.g., via one or more flow paths) to the point of use. Furthermore, the mixing device may comprise more than one chamber, each chamber having at least one inlet and at least one outlet, wherein two or more components are combined in each chamber. If a container-type mixing device is used, then the mixing device preferably includes a mixing mechanism to further facilitate the combination of components. Mixing mechanisms are generally known in the field and include stirrers, mixers, agitators, paddle baffles, gas bubbler systems, vibrators, etc.

[0060] The polishing composition may also be provided as a concentrate, which is intended to be diluted with an appropriate amount of water prior to use. In this embodiment, the polishing composition concentrate contains a certain amount of polishing composition components such that, after diluting the concentrate with an appropriate amount of water, each component of the polishing composition will be present in the polishing composition in an amount within the appropriate range listed above for each component. For example, titanium oxide abrasives, oxidants, optional pH adjusters, and / or any optional additives may each be present in the concentrate in an amount approximately twice (e.g., approximately three times, approximately four times, or approximately five times) the concentrations listed above for each component, such that when the concentrate is diluted with equal volumes of water (e.g., two, three, or four equal volumes of water, respectively), each component will be present in the polishing composition in an amount within the range set forth above for each component. Furthermore, as those skilled in the art will understand, the concentrate may contain an appropriate proportion of water present in the final polishing composition to ensure that the titanium oxide abrasives, oxidants, optional pH adjusters, and / or any optional additives are at least partially or completely dissolved in the concentrate.

[0061] The present invention further provides a method for chemical mechanical polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition comprising: (a) a titanium oxide abrasive; (b) an oxidant; and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the substrate, thereby polishing the substrate.

[0062] The substrate can be any suitable substrate. In some embodiments, the substrate comprises boron-doped polysilicon, such as a boron-polysilicon alloy. Therefore, the method may include providing a substrate comprising a boron-doped polysilicon layer on a substrate surface, wherein at least a portion of the boron-doped polysilicon layer on the substrate surface is ground to polish the substrate. Alternatively, or additionally, the substrate may comprise a silicon nitride layer, a silicon oxide layer, a titanium nitride layer, or a combination thereof on a substrate surface. Therefore, by way of example, the method may include providing a substrate comprising: (i) a silicon nitride layer on a substrate surface, wherein at least a portion of the silicon nitride layer on the substrate surface is ground to polish the substrate; (ii) a silicon oxide layer on a substrate surface, wherein at least a portion of the silicon oxide layer on the substrate surface is ground to polish the substrate; and / or (iii) a titanium nitride layer on a substrate surface, wherein at least a portion of the titanium nitride layer on the substrate surface is ground to polish the substrate. In some embodiments, the substrate comprises a boron-doped polysilicon layer on a substrate surface, and a silicon oxide layer, a silicon nitride layer, and / or a titanium nitride layer on a substrate surface.

[0063] Boron-doped polysilicon can be any suitable boron-doped polysilicon, many of which are known in the art. The polysilicon can have any suitable phase and can be amorphous, crystalline, or a combination thereof. The boron doping level can be any suitable level. Generally, a boron-doped polysilicon layer contains at least 75 wt.% boron, at least 80 wt.% boron, at least 85 wt.% boron, or at least 90 wt.% boron. For example, the boron-doped polycrystalline silicon layer may contain about 75 wt.% to about 99.9 wt.% boron, such as 75 wt.% to about 99 wt.%, about 75 wt.% to about 95 wt.%, about 75 wt.% to about 90 wt.%, about 80 wt.% to about 99.9 wt.%, about 80 wt.% to about 99 wt.%, about 80 wt.% to about 95 wt.%, about 80 wt.% to about 90 wt.%, about 85 wt.% to about 99.9 wt.%, about 85 wt.% to about 99 wt.%, about 85 wt.% to about 95 wt.%, about 85 wt.% to about 90 wt.%, about 90 wt.% to about 99.9 wt.%, about 90 wt.% to about 99 wt.%, about 90 wt.% to about 95 wt.%, about 95 wt.% to about 99.9 wt.%. The boron doping content is wt.% or about 95 wt.% to about 99 wt.%. In some embodiments, the boron-doped polycrystalline silicon layer contains at least 95 wt.% boron. Without wishing to be bound by any particular theory, it is believed that the compositions and methods presented herein are particularly suitable for polishing boron-doped polycrystalline silicon with high levels (e.g., about 80 wt.% or more, about 85 wt.% or more, about 90 wt.% or more, or about 95 wt.% or more) boron doping.

[0064] When polishing a boron-doped polycrystalline silicon substrate according to the method of the present invention, the polishing composition of the present invention is expected to exhibit a high removal rate. For example, when polishing a silicon wafer containing a boron-doped polycrystalline silicon layer according to embodiments of the present invention, the polishing composition is expected to exhibit a boron-doped polycrystalline silicon removal rate of about 500 Å / min or higher, such as about 550 Å / min or higher, about 600 Å / min or higher, about 650 Å / min or higher, about 700 Å / min or higher, about 750 Å / min or higher, about 800 Å / min or higher, about 850 Å / min or higher, about 900 Å / min or higher, about 950 Å / min or higher, about 1000 Å / min or higher, about 1100 Å / min or higher, about 1200 Å / min or higher, about 1300 Å / min or higher, about 1400 Å / min or higher, about 1500 Å / min or higher, about 1600 Å / min or higher, about 1700 Å / min or higher, about 1800 Å / min or higher. Removal rates of approximately 1900 Å / min or higher, approximately 2000 Å / min or higher, approximately 2100 Å / min or higher, approximately 2200 Å / min or higher, approximately 2300 Å / min or higher, approximately 2400 Å / min or higher, approximately 2500 Å / min or higher, approximately 2600 Å / min or higher, approximately 2700 Å / min or higher, approximately 2800 Å / min or higher, approximately 2900 Å / min or higher, approximately 3000 Å / min or higher, approximately 3500 Å / min or higher, approximately 4000 Å / min or higher, or approximately 4500 Å / min or higher.

[0065] In some embodiments, where the substrate further comprises titanium nitride, the titanium nitride can be any suitable titanium nitride, many of which are known in the art. When a substrate containing titanium nitride is polished according to the method of the invention, the chemical mechanical polishing composition of the invention is expected to exhibit a high removal rate. For example, when polishing a substrate containing titanium nitride according to embodiments of the present invention, the polishing composition desiccates to exhibit a titanium nitride removal rate of about 500 Å / min or higher, such as about 550 Å / min or higher, about 600 Å / min or higher, about 650 Å / min or higher, about 700 Å / min or higher, about 750 Å / min or higher, about 800 Å / min or higher, about 850 Å / min or higher, about 900 Å / min or higher, about 950 Å / min or higher, about 1000 Å / min or higher, about 1100 Å / min or higher, about 1200 Å / min or higher, about 1300 Å / min or higher, about 1400 Å / min or higher, about 1500 Å / min or higher, about 1600 Å / min or higher, about 1700 Å / min or higher, about 1800 Å / min or higher. Removal rates of approximately 1900 Å / min or higher, approximately 2000 Å / min or higher, approximately 2100 Å / min or higher, approximately 2200 Å / min or higher, approximately 2300 Å / min or higher, approximately 2400 Å / min or higher, approximately 2500 Å / min or higher, approximately 2600 Å / min or higher, approximately 2700 Å / min or higher, approximately 2800 Å / min or higher, approximately 2900 Å / min or higher, approximately 3000 Å / min or higher, approximately 3500 Å / min or higher, approximately 4000 Å / min or higher, or approximately 4500 Å / min or higher.

[0066] In some embodiments, where the substrate further comprises silicon oxide, the silicon oxide can be any suitable silicon oxide, many of which are known in the art. Suitable types of silicon oxide include, but are not limited to, borophosphosilicate glass (BPSG), tetraethyl orthosilicate (TEOS), plasma-enhanced tetraethyl orthosilicate (PETEOS), thermal oxides, undoped silicate glass, and high-density plasma (HDP) oxides. When polishing a silicon oxide-containing substrate according to the method of the invention, the chemical mechanical polishing composition of the invention is expected to exhibit a low silicon oxide removal rate. For example, when polishing a silicon oxide-containing substrate according to embodiments of the invention, the polishing composition is expected to exhibit a silicon oxide removal rate of about 500 Å / min or less, such as about 250 Å / min or less, about 200 Å / min or less, about 150 Å / min or less, about 100 Å / min or less, about 50 Å / min or less, about 25 Å / min or less, about 10 Å / min or less, or about 5 Å / min or less. In some embodiments, the polishing composition exhibits a silica removal rate that is too low to be detected.

[0067] In some embodiments, where the substrate further comprises silicon nitride, the silicon nitride can be any suitable silicon nitride, many of which are known in the art. When polishing a silicon nitride-containing substrate according to the method of the invention, the chemical mechanical polishing composition of the invention desiccates to exhibit a low silicon nitride removal rate. For example, when polishing a silicon nitride-containing substrate according to embodiments of the invention, the polishing composition desiccates to exhibit a silicon nitride removal rate of about 500 Å / min or less, such as about 250 Å / min or less, about 200 Å / min or less, about 150 Å / min or less, about 100 Å / min or less, about 50 Å / min or less, about 25 Å / min or less, about 10 Å / min or less, or about 5 Å / min or less. In some embodiments, the polishing composition exhibits a silicon nitride removal rate that is too low to be detectable.

[0068] The chemical mechanical polishing (CMP) compositions of the present invention can be customized to provide effective polishing within a desired range of selective polishing for a particular thin-layer material, while minimizing surface imperfections, defects, corrosion, erosion, and removal of the terminating layer. Selectivity can be controlled to some extent by varying the relative concentrations of the components in the polishing composition. When desired, the CMP compositions of the present invention can be used to polish substrates comprising boron-doped polysilicon and silicon oxide on a surface layer, wherein the CMP compositions provide polishing selectivity of about 5:1 or higher (e.g., about 10:1 or higher, about 15:1 or higher, about 25:1 or higher, about 50:1 or higher, about 100:1 or higher, or about 150:1 or higher) for boron-doped polysilicon to silicon oxide. Furthermore, the chemical mechanical polishing (CMP) composition of the present invention can be used to polish substrates comprising boron-doped polysilicon and silicon nitride on a surface layer, wherein the CMP composition provides polishing selectivity of boron-doped polysilicon to silicon nitride at about 3:1 or higher (e.g., about 5:1 or higher, about 10:1 or higher, about 15:1 or higher, about 25:1 or higher, about 50:1 or higher, about 100:1 or higher, or about 150:1 or higher). Therefore, in embodiments, when used to polish a substrate comprising at least one boron-doped polysilicon layer and at least one silicon oxide layer and / or at least one silicon nitride layer, the polishing composition and polishing method allow preferential removal of boron-doped polysilicon compared to the removal of silicon oxide and / or silicon nitride. As used herein, the phrase "polishing selectivity" refers to the ratio of the removal rates of two different thin-layer materials.

[0069] The chemical mechanical polishing (CMP) composition of the present invention can also be used to polish substrates comprising boron-doped polysilicon and titanium nitride on a surface layer, wherein the CMP composition provides polishing selectivity of about 20:1 or lower (e.g., about 10:1 or lower, about 5:1 or lower, about 4:1 or lower, about 3:1 or lower, or about 2:1 or lower) for boron-doped polysilicon and titanium nitride. When polishing substrates comprising both boron-doped polysilicon and titanium nitride according to the method of the present invention, the CMP composition of the present invention desiccates to exhibit high removal rates. Therefore, in the presence of silicon oxide and / or silicon nitride, the CMP composition of the present invention can be used to selectively remove boron-doped polysilicon and / or titanium nitride.

[0070] When polishing a substrate, the polishing composition of the present invention is expected to exhibit low particle defects, as determined by a suitable technique. Particle defects on a substrate polished by the inventive polishing composition can be determined by any suitable technique. For example, laser light scattering techniques (e.g., dark field normal beam complex (DCN) and dark field tilted beam complex (DCO)) can be used to determine particle defects on a polished substrate. Suitable instruments for assessing particle defect levels are available, for example, from KLA-Tencor (e.g., a SURFSCAN operating at a 120 nm threshold or a 160 nm threshold). TM SPI instruments).

[0071] The chemical mechanical polishing composition and method of the present invention are particularly suitable for use in conjunction with chemical mechanical polishing equipment. Typically, the equipment includes: a pressure plate that is in motion during use and has a speed generated by tracked, linear, or circular motion; a polishing pad that contacts the pressure plate and moves with the pressure plate during motion; and a carrier that holds a substrate to be polished by contacting and moving the substrate relative to the surface of the polishing pad. Polishing of the substrate is performed by the following steps: placing the substrate in contact with the polishing pad and the polishing composition of the present invention, and then moving the polishing pad relative to the substrate to abrade at least a portion of the substrate, thereby polishing the substrate.

[0072] Substrates can be polished using any suitable polishing pad (e.g., polishing surface) with a chemical mechanical polishing composition. Suitable polishing pads include, for example, woven and nonwoven polishing pads. Furthermore, suitable polishing pads may contain any suitable polymer with different densities, hardness, thickness, compressibility, resilience after compression, and compressive modulus. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbons, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene, co-formed products thereof, and mixtures thereof. Soft polyurethane polishing pads are particularly suitable for use with inventive polishing methods. Typical pads include, but are not limited to, SURFIN. TM 000, SURFIN TM SSW1, SPM3100 (commercially available from companies such as Emines Technologies), POLITEX TM EPIC TM D100 pad (commercially available from CMC Materials), IC1010 TM Mattresses (available commercially from Dow Chemical Company, Inc.) and Fujibo Polypas TM 27.

[0073] Desiredly, chemical mechanical polishing (CMP) equipment further includes in-situ polishing endpoint detection systems, many of which are known in the art. Techniques for detecting and monitoring the polishing process by analyzing light or other radiation reflected from the surface of a polished substrate are known in the art. Such methods are described, for example, in U.S. Patent Nos. 5,196,353, 5,433,651, 5,609,511, 5,643,046, 5,658,183, 5,730,642, 5,838,447, 5,872,633, 5,893,796, 5,949,927, and 5,964,643. Desiredly, detecting or monitoring the progress of the polishing process on a polished substrate enables the determination of polishing endpoints, that is, determining when to terminate the polishing process on a particular substrate.

[0074] The substrate can be polished using any suitable downforce. For example, the substrate can be polished using a downforce of about 1 psi or greater, about 2 psi or greater, about 3 psi or greater, about 4 psi or greater, or about 5 psi or greater. Alternatively, or additionally, the substrate can be polished using a downforce of about 10 psi or less, about 8 psi or less, about 6 psi or less, about 4 psi or less, or about 2 psi or less. Therefore, the substrate can be polished using a downforce defined by any two of the aforementioned endpoints. For example, the substrate can be polished using a downforce of about 1 psi to about 10 psi, about 2 psi to about 10 psi, about 1 psi to about 8 psi, about 2 psi to about 8 psi, about 1 psi to about 6 psi, about 2 psi to about 6 psi, about 1 psi to about 4 psi, or about 2 psi to about 4 psi.

[0075] In some embodiments, the present invention provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate, wherein the substrate comprises a boron-doped polycrystalline silicon layer on a substrate surface; (ii) providing a polishing pad; (iii) providing a chemically mechanically polishing composition comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of a permanganate (e.g., potassium permanganate); and (c) water, wherein the chemically mechanically polishing composition has a pH of about 7 or lower; (iv) contacting the substrate with the polishing pad and the chemically mechanically polishing composition; and (v) moving the polishing pad and the chemically mechanically polishing composition relative to the substrate to abrade at least a portion of the boron-doped polycrystalline silicon layer on the substrate surface, thereby polishing the substrate.

[0076] In some embodiments, the present invention provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate, wherein the substrate comprises a boron-doped polycrystalline silicon layer on a substrate surface; (ii) providing a polishing pad; (iii) providing a chemically mechanically polishing composition comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of a permanganate (e.g., potassium permanganate); (c) a dispersant; and (d) water, wherein the chemically mechanically polishing composition has a pH of about 7 or less; (iv) contacting the substrate with the polishing pad and the chemically mechanically polishing composition; and (v) moving the polishing pad and the chemically mechanically polishing composition relative to the substrate to abrade at least a portion of the boron-doped polycrystalline silicon layer on the substrate surface, thereby polishing the substrate.

[0077] In some embodiments, the present invention provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate, wherein the substrate comprises a boron-doped polycrystalline silicon layer on a substrate surface; (ii) providing a polishing pad; (iii) providing a chemically mechanically polishing composition comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of cerium ammonium nitrate; and (c) water, wherein the chemically mechanically polishing composition has a pH of about 7 or less; (iv) contacting the substrate with the polishing pad and the chemically mechanically polishing composition; and (v) moving the polishing pad and the chemically mechanically polishing composition relative to the substrate to abrade at least a portion of the boron-doped polycrystalline silicon layer on the substrate surface, thereby polishing the substrate.

[0078] In some embodiments, the present invention provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate, wherein the substrate comprises a boron-doped polycrystalline silicon layer on a substrate surface; (ii) providing a polishing pad; (iii) providing a chemically mechanically polishing composition comprising: (a) a titanium oxide abrasive; (b) at least 1 wt.% (e.g., 1 wt.% to 20 wt.%, 1 wt.% to 10 wt.%, or 1 wt.% to 5 wt.%) of cerium ammonium nitrate; (c) a dispersant; and (d) water, wherein the chemically mechanically polishing composition has a pH of about 7 or less; (iv) contacting the substrate with the polishing pad and the chemically mechanically polishing composition; and (v) moving the polishing pad and the chemically mechanically polishing composition relative to the substrate to abrade at least a portion of the boron-doped polycrystalline silicon layer on the substrate surface, thereby polishing the substrate.

[0079] The aspects of the invention described above (including embodiments) may be advantageous individually or in combination with one or more other aspects or embodiments. Without limiting the foregoing description, certain non-limiting embodiments of this disclosure, numbered 1 to 63, are provided below. It will be apparent to those skilled in the art upon reading this disclosure that each of the individually numbered embodiments may be used or combined with any of the preceding or subsequent individually numbered embodiments. This is intended to support all such combinations of embodiments, and not be limited to the combinations of embodiments explicitly provided below:

[0080] Example

[0081] (1) A chemical mechanical polishing composition is presented in Example (1), comprising:

[0082] (a) Titanium oxide abrasive;

[0083] (b) Oxidizing agents; and

[0084] (c) Water,

[0085] The chemical mechanical polishing composition described herein has a pH of about 7 or less.

[0086] (2) The polishing composition according to Example (1) is presented in Example (2), wherein the polishing composition has a pH of about 6 or less.

[0087] (3) The polishing composition according to Example (1) or Example (2) is presented in Example (3), wherein the polishing composition has a pH of about 5 or less.

[0088] (4) In Example (4), a polishing composition according to any one of Examples (1) to (3) is presented, wherein the polishing composition comprises about 0.001 wt.% to about 10 wt.% of the titanium oxide abrasive.

[0089] (5) In Example (5), a polishing composition according to any one of Examples (1) to (4) is presented, wherein the polishing composition comprises about 0.025 wt.% to about 5 wt.% of the titanium oxide abrasive.

[0090] (6) In Example (6), a polishing composition according to any one of Examples (1) to (5) is presented, wherein the titanium oxide abrasive is substantially pure rutile titanium oxide.

[0091] (7) The polishing composition according to any one of Examples (1) to (6) is presented in Example (7), wherein the titanium oxide abrasive has an average particle size of about 10 nm to about 300 nm.

[0092] (8) In Example (8), a polishing composition according to any one of Examples (1) to (7) is presented, wherein the titanium oxide abrasive has an average particle size of about 50 nm to about 150 nm.

[0093] (9) In Example (9), a polishing composition according to any of Examples (1) to (8) is presented, wherein the oxidant is selected from potassium persulfate, cerium ammonium nitrate, peroxide, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, and combinations thereof.

[0094] (10) In Example (10), a polishing composition according to any of Examples (1) to (9) is presented, wherein the oxidant is selected from permanganate, cerium ammonium nitrate and combinations thereof.

[0095] (11) In Example (11), a polishing composition according to any of Examples (1) to (10) is presented, wherein the oxidant is cerium ammonium nitrate.

[0096] (12) In Example (12), a polishing composition according to any one of Examples (1) to (10) is presented, wherein the oxidant is potassium permanganate.

[0097] (13) A polishing composition according to any one of Examples (1) to (12) is presented in Example (13), wherein the polishing composition comprises 1 wt.% to 20 wt.% of the oxidant.

[0098] (14) A polishing composition according to any one of Examples (1) to (13) is presented in Example (14), wherein the polishing composition comprises 2 wt.% to 20 wt.% of the oxidant.

[0099] (15) A polishing composition according to any one of Examples (1) to (14) is presented in Example (15), wherein the polishing composition comprises 3 wt.% to 20 wt.% of the oxidant.

[0100] (16) A polishing composition according to any one of Examples (1) to (15) is presented in Example (16), wherein the polishing composition further comprises iron ions.

[0101] (17) A polishing composition according to Example (16) is presented in Example (17), wherein the polishing composition contains about 0.01 wt.% to about 1 wt.% of iron ions.

[0102] (18) In Example (18), a polishing composition according to any one of Examples (1) to (15) is presented, wherein the polishing composition is substantially free of iron ions.

[0103] (19) A polishing composition according to any one of Examples (1) to (18) is presented in Example (19), wherein the polishing composition further comprises an organic acid.

[0104] (20) The polishing composition according to Example (19) is presented in Example (20), wherein the organic acid is selected from maleic acid, citric acid, L-ascorbic acid, pyridinecarboxylic acid, malonic acid and combinations thereof.

[0105] (21) A polishing composition according to Example (19) or Example (20) is presented in Example (21), wherein the polishing composition comprises about 1 mM to about 100 mM of the organic acid.

[0106] (22) A polishing composition according to any one of Examples (1) to (18) is presented in Example (22), wherein the polishing composition is substantially free of organic acids.

[0107] (23) A polishing composition according to any one of Examples (1) to (22) is presented in Example (23), wherein the polishing composition further comprises a buffer.

[0108] (24) The polishing composition according to Example (23) is presented in Example (24), wherein the buffer is selected from ammonium salts, alkali metal salts, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, amino acids and combinations thereof.

[0109] (25) A polishing composition according to any one of Examples (1) to (24) is presented in Example (25), wherein the polishing composition further comprises a dispersant.

[0110] (26) The polishing composition according to Example (25) is presented in Example (26), wherein the dispersant comprises polyethylene oxide.

[0111] (27) A method for chemically mechanically polishing a substrate is presented in Example (27), comprising:

[0112] (i) Provide a substrate,

[0113] (ii) Provide polishing pads,

[0114] (iii) Providing a chemical mechanical polishing composition, said chemical mechanical polishing composition comprising:

[0115] (a) Titanium oxide abrasive;

[0116] (b) Oxidizing agents; and

[0117] (c) Water,

[0118] The chemimechanical polishing composition described herein has a pH of about 7 or less.

[0119] (iv) Contact the substrate with the polishing pad and the chemical mechanical polishing composition, and

[0120] (v) The polishing pad and the chemical mechanical polishing composition are moved relative to the substrate to grind at least a portion of the substrate, thereby polishing the substrate.

[0121] (28) The method according to Example (27) is presented in Example (28), wherein the polishing composition has a pH of about 6 or less.

[0122] (29) The method according to Example (27) or Example (28) is presented in Example (29), wherein the polishing composition has a pH of about 5 or less.

[0123] (30) The method according to any one of the embodiments of (27) to (29) is presented in Example (30), wherein the polishing composition comprises about 0.001 wt.% to about 10 wt.% of the titanium oxide abrasive.

[0124] (31) The method according to any one of the embodiments of (27) to (30) is presented in Example (31), wherein the polishing composition comprises about 0.025 wt.% to about 5 wt.% of the titanium oxide abrasive.

[0125] (32) The method according to any of the embodiments of (27) to (31) is presented in Example (32), wherein the titanium oxide abrasive is substantially pure rutile titanium oxide.

[0126] (33) The method according to any of the embodiments of (27) to (32) is presented in Example (33), wherein the titanium oxide abrasive has an average particle size of about 10 nm to about 300 nm.

[0127] (34) The method according to any one of the embodiments of (27) to (33) is presented in Example (34), wherein the titanium oxide abrasive has an average particle size of about 50 nm to about 150 nm.

[0128] (35) The method according to any of the embodiments of (27) to (34) is presented in Example (35), wherein the oxidant is selected from potassium persulfate, cerium ammonium nitrate, peroxide, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate and combinations thereof.

[0129] (36) The method according to any of the embodiments of (27) to (35) is presented in Example (36), wherein the oxidant is selected from permanganate, cerium ammonium nitrate and combinations thereof.

[0130] (37) The method according to any one of the embodiments of (27) to (36) is presented in Example (37), wherein the oxidant is cerium ammonium nitrate.

[0131] (38) The method according to any one of the embodiments of (27) to (36) is presented in Example (38), wherein the oxidant is potassium permanganate.

[0132] (39) The method according to any of the embodiments of (27) to (38) is presented in Example (39), wherein the polishing composition comprises 1 wt.% to 20 wt.% of the oxidant.

[0133] (40) The method according to any one of the embodiments (27) to (39) is presented in Example (40), wherein the polishing composition comprises 2 wt.% to 20 wt.% of the oxidant.

[0134] (41) The method according to any one of the embodiments of (27) to (40) is presented in Example (41), wherein the polishing composition comprises 3 wt.% to 20 wt.% of the oxidant.

[0135] (42) The method according to any of the embodiments of (27) to (41) is presented in Example (42), wherein the polishing composition further comprises iron ions.

[0136] (43) The method according to Example (42) is presented in Example (43), wherein the polishing composition comprises about 0.01 wt.% to about 1 wt.% of iron ions.

[0137] (44) The method described in any of the embodiments of (27) to (41) is presented in Example (44), wherein the polishing composition is substantially free of iron ions.

[0138] (45) The method according to any one of the embodiments of (27) to (44) is presented in Example (45), wherein the polishing composition further comprises an organic acid.

[0139] (46) The method according to Example (45) is presented in Example (46), wherein the organic acid is selected from maleic acid, citric acid, L-ascorbic acid, pyridinecarboxylic acid, malonic acid and combinations thereof.

[0140] (47) The method according to Example (45) or Example (46) is presented in Example (47), wherein the polishing composition comprises about 1 mM to about 100 mM of organic acid.

[0141] (48) The method described in any of the embodiments of (27) to (44) is presented in Example (48), wherein the polishing composition is substantially free of organic acids.

[0142] (49) The method according to any one of the embodiments of (27) to (48) is presented in Example (49), wherein the polishing composition further comprises a buffer.

[0143] (50) The method according to Example (49) is presented in Example (50), wherein the buffer is selected from ammonium salts, alkali metal salts, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, amino acids and combinations thereof.

[0144] (51) The method according to any one of the embodiments (27) to (50) is presented in Example (51), wherein the polishing composition further comprises a dispersant.

[0145] (52) The method according to Example (51) is presented in Example (52), wherein the dispersant comprises polyethylene oxide.

[0146] (53) The method according to any one of the embodiments (27) to (52) is presented in embodiment (53), wherein the substrate comprises a boron-doped polysilicon layer on the surface of the substrate, and at least a portion of the boron-doped polysilicon layer on the surface of the substrate is ground to polish the substrate.

[0147] (54) The method according to Example (53) is presented in Example (54), wherein the boron-doped polycrystalline silicon layer comprises at least 80 wt.% boron.

[0148] (55) The method according to Example (53) is presented in Example (55), wherein the boron-doped polycrystalline silicon layer comprises at least 85 wt.% boron.

[0149] (56) The method according to Example (53) is presented in Example (56), wherein the boron-doped polycrystalline silicon layer comprises at least 90 wt.% boron.

[0150] (57) The method according to any one of the embodiments (53) to (56) is presented in embodiment (57), wherein the substrate further comprises a silicon nitride layer on the surface of the substrate, and wherein at least a portion of the silicon nitride layer on the surface of the substrate is ground to polish the substrate.

[0151] (58) The method according to Example (57) is presented in Example (58), wherein the chemical mechanical polishing composition provides polishing selectivity of about 3:1 or higher for boron-doped polycrystalline silicon to silicon nitride.

[0152] (59) The method according to any one of the embodiments (53) to (58) is presented in embodiment (59), wherein the substrate further comprises a silicon oxide layer on the surface of the substrate, and wherein at least a portion of the silicon oxide layer on the surface of the substrate is ground to polish the substrate.

[0153] (60) The method according to Example (59) is presented in Example (60), wherein the chemical mechanical polishing composition provides polishing selectivity of about 5:1 or higher for boron-doped polycrystalline silicon to silicon oxide.

[0154] (61) The method according to any one of the embodiments (53) to (60) is presented in embodiment (61), wherein the substrate further comprises a titanium nitride layer on the surface of the substrate, and wherein at least a portion of the titanium nitride layer on the surface of the substrate is ground to polish the substrate.

[0155] (62) The method according to Example (61) is presented in Example (62), wherein the chemical mechanical polishing composition provides polishing selectivity of boron-doped polycrystalline silicon to titanium nitride at a ratio of about 5:1 or lower.

[0156] (63) The method according to Example (61) or Example (62) is presented in Example (63), wherein the chemical mechanical polishing composition provides polishing selectivity of about 3:1 or less for titanium nitride to silicon oxide.

[0157] Example

[0158] The following examples further illustrate the invention, but should not be construed as limiting its scope in any way.

[0159] The following abbreviations are used throughout the examples: Removal Rate (RR); Boron-Doped Polycrystalline Silicon (BSi); Silicon Oxide (Ox); Titanium Nitride (TiN); Weight Percentage (wt.%); and Pounds per Square Inch (psi).

[0160] Example 1

[0161] This example demonstrates the effect of the type and amount of abrasive particles and oxidant on the polishing performance of the polishing composition prepared according to the present invention.

[0162] Polishing compositions 1A to 1F contain 0.025 wt.% silica (SiO2) abrasive particles or 1 wt.% titanium oxide (TiO2) abrasive, 2 wt.% polyethylene oxide dispersant for the titanium oxide (TiO2) abrasive only, and the oxidants and additives shown in Table 1. A / B mixtures are used in all formulations, wherein the particulate dispersion (package A) is formulated at pH 2.85 and proportionally mixed with the oxidant (package B) to obtain a final slurry composition for polishing silica, titanium nitride, and boron polycrystalline silicon alloys. The final slurry has a pH of approximately 1 at the point of use.

[0163] Under a downforce of 3 PSI (20.55 kPa), a Logitech 2 benchtop polisher was used with a product commercially labeled SAESOL. TM DS8051 (SAESOL Diamond Ind. Co. Ltd.) product adjustment NexPlanar TM The U5890 pad (CMC Materials) was used to polish patterned substrates comprising the following: a tetraethyl orthosilicate (i.e., silicon oxide (Ox)) layer, a boron-doped polycrystalline silicon (BSi) layer containing approximately 95 wt.% boron, or a titanium nitride (TiN) layer coated on a wafer, using polishing compositions 1A to 1F as defined in Table 1. Logitech polishing parameters were as follows: head speed = 86 rpm, platen speed = 93 rpm, total flow rate = 50 mL / min. All patterned substrates were polished for 60 seconds. The removal rate was calculated by measuring the film thickness using a spectroscopic elipsometry and subtracting the final thickness from the initial thickness. The results are shown in Table 1. Selectivity (Å / min) in Table 1 refers to the polishing rate of BSi and TiN relative to the polishing rate of TEOS (i.e., Ox).

[0164] Table 1. Polishing composition removal rate as a function of oxidant and abrasive.

[0165]

[0166] As evident from the results shown in Table 1, the silica compositions containing cerium ammonium nitrate (CAN) and optional additional oxidants (e.g., persulfate and iodate) exhibit low TiN removal rates, as illustrated in comparative polishing compositions 1A, 1B, and 1C. Table 1 also shows that, as illustrated in comparative polishing composition 1D, the addition of citric acid resulted in a small increase in TiN removal rate. As illustrated in comparative polishing composition 1E, replacing the silica abrasive with a titanium oxide abrasive in the absence of cerium ammonium nitrate (CAN) did not show any increase in TiN removal rate. However, the inventive polishing composition 1F, containing titanium oxide and cerium ammonium nitrate (CAN), exhibited high TiN and BSi removal rates while maintaining low Ox removal rates. Therefore, Table 1 demonstrates that titanium oxide abrasives and oxidants desirously provide high TiN and BSi removal rates while maintaining low Ox removal rates.

[0167] Example 2

[0168] This example illustrates the effect of dispersants on the polishing properties of polishing compositions prepared according to the present invention.

[0169] Polishing compositions 2A to 2D contain 0.1 wt.% titanium oxide (TiO2) abrasive, 1.8 wt.% cerium ammonium nitrate (CAN), and polyethylene oxide dispersant in the amounts shown in Table 2. A / B mixtures are used in all formulations, wherein the particulate dispersion (Package A) is formulated at pH 2.85 and proportionally mixed with the oxidant (Package B) to obtain the final slurry composition for polishing silica, titanium nitride, and boron polycrystalline silicon alloys. Prior to manufacturing Package A, the titanium oxide (TiO2) abrasive is treated with polyethylene oxide dispersant to improve the colloidal stability and redispersibility of the settled particles in the container. The final slurry has a pH of approximately 1 at the point of use.

[0170] Under a downforce of 3 PSI (20.55 kPa), a Logitech 2 benchtop polisher was used with a product commercially labeled SAESOL. TM DS8051 (SAESOL Diamond Industries Ltd.) product adjustment NexPlanar TMThe U5890 pad (CMC Materials) was used to polish patterned substrates comprising the following: a tetraethyl orthosilicate (i.e., silicon oxide (Ox)) layer, a boron-doped polycrystalline silicon (BSi) layer containing approximately 95 wt.% boron, or a titanium nitride (TiN) layer coated on a wafer, using polishing compositions 2A to 2D as defined in Table 2. Logitech polishing parameters were as follows: head speed = 86 rpm, platen speed = 93 rpm, total flow rate = 50 mL / min. All patterned substrates were polished for 60 seconds. The removal rate was calculated by measuring the film thickness using an ellipsometry and subtracting the final thickness from the initial thickness. The results are shown in Table 2. The selectivity (Å / min) in Table 2 refers to the polishing rate of BSi and TiN relative to the polishing rate of TEOS (i.e., Ox).

[0171] Table 2. Polishing composition removal rate as a function of dispersant concentration

[0172]

[0173] The results shown in Table 2 clearly demonstrate that, as illustrated in inventive polishing composition 2A, low concentrations of dispersant exhibit high TiN removal rates but inhibit BSi removal. Without being bound by any particular theory, it is thought that the titanium oxide abrasive particles of inventive polishing composition 2A, prior to mixing with the oxidant, have a significantly larger particle size in package A, which may have prevented any mechanical removal of BSi. Similarly, as illustrated in inventive polishing composition 2C, high concentrations of dispersant exhibit high TiN removal rates but inhibit BSi removal.

[0174] Inventive polishing composition 2B, containing 2 wt.% dispersant, exhibits high TiN and BSi removal rates while maintaining low Ox removal rates. In contrast, comparative polishing composition 2D, having the same composition as inventive polishing composition 2B except for the absence of the oxidant cerium ammonium nitrate (CAN), exhibits low TiN and BSi removal rates. These results demonstrate that the combination of titanium oxide (TiO2) abrasives with an oxidant desiccants preferably provides high TiN and / or BSi removal rates while maintaining low Ox removal rates. These results also demonstrate that the addition of a dispersant, preferably in an amount of about 0.5 wt.% or greater and about 4 wt.% or less, helps to improve the colloidal stability and redispersibility of settled particles and desiccates high TiN and BSi removal rates while maintaining low Ox removal rates.

[0175] All references cited in this document (including publications, patent applications and patents) are hereby incorporated by reference as if each reference were individually and specifically indicated to be incorporated by reference and described in full in this document.

[0176] Unless otherwise indicated herein or obviously contradicted by the context, the use of the terms “a” and “an” and “the” and “at least one” and similar indicators in the context of describing the invention (especially in the context of the following claims) should be understood to cover both the singular and the plural. Unless otherwise indicated herein or obviously contradicted by the context, the use of the term “at least one” following a list of one or more items (e.g., “at least one of A and B”) should be understood to mean one item (A or B) selected from the list or any combination of two or more of the list items (A and B). Unless otherwise indicated, the terms “comprising,” “having,” “including,” and “containing” should be understood as open-ended terms (i.e., meaning “including but not limited to”). Unless otherwise indicated, the enumeration of value ranges herein is intended only as a way of individually referring to each individual value belonging to the range, and each individual value is incorporated into this specification as if individually enumerated herein. Unless otherwise indicated herein or obviously contradicted by the context, all methods described herein can be performed in any suitable order. Unless otherwise required, the use of any and all examples or exemplary language (e.g., “for example”) provided herein is intended only to better illustrate the invention and not to limit its scope. The language in this specification should not be construed as indicating that any unclaimed element is necessary for practicing the invention.

[0177] Preferred embodiments of the invention are described herein, including the most preferred modes known to the inventors for carrying out the invention. Variations of those preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect those skilled in the art to adopt such variations where appropriate, and the inventors intend to practice the invention in ways other than those specifically described herein. Therefore, the invention includes all modifications and equivalents of the subject matter set forth in the appended claims, where permitted by applicable law. Furthermore, unless otherwise indicated herein or otherwise clearly contradicted by the context, the invention covers any combination of the elements described above in all possible variations.

Claims

1. A chemical mechanical polishing composition comprising: (a) Titanium oxide abrasive, wherein the titanium oxide abrasive is substantially pure rutile titanium oxide; (b) Oxidizing agents; and (c) Water, The chemical mechanical polishing composition described herein has a pH of about 7 or lower.

2. The polishing composition according to claim 1, wherein the polishing composition has a pH of about 6 or lower.

3. The polishing composition according to claim 1, wherein the polishing composition has a pH of about 5 or lower.

4. The polishing composition of claim 1, wherein the polishing composition comprises about 0.001 wt.% to about 10 wt.% of the titanium oxide abrasive.

5. The polishing composition according to claim 1, wherein the polishing composition comprises about 0.025 wt.% to about 5 wt.% of the titanium oxide abrasive.

6. The polishing composition according to claim 1, wherein the titanium oxide abrasive has an average particle size of about 10 nm to about 300 nm.

7. The polishing composition according to claim 1, wherein the titanium oxide abrasive has an average particle size of about 50 nm to about 150 nm.

8. The polishing composition according to claim 1, wherein the oxidant is selected from potassium persulfate, cerium ammonium nitrate, peroxide, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, and combinations thereof.

9. The polishing composition according to claim 1, wherein the oxidant is selected from permanganate, cerium ammonium nitrate, and combinations thereof.

10. The polishing composition according to claim 9, wherein the oxidant is cerium ammonium nitrate.

11. The polishing composition according to claim 9, wherein the oxidant is potassium permanganate.

12. The polishing composition of claim 1, wherein the polishing composition comprises 1 wt.% to 20 wt.% of the oxidant.

13. The polishing composition according to claim 1, wherein the polishing composition further comprises iron ions.

14. The polishing composition of claim 13, wherein the polishing composition comprises about 0.01 wt.% to about 1 wt.% of iron ions.

15. The polishing composition of claim 1, wherein the polishing composition is substantially free of iron ions.

16. The polishing composition of claim 1, wherein the polishing composition further comprises an organic acid of about 1 mM to about 100 mM.

17. The polishing composition according to claim 16, wherein the organic acid is selected from maleic acid, citric acid, L-ascorbic acid, pyridinecarboxylic acid, malonic acid, and combinations thereof.

18. The polishing composition of claim 1, wherein the polishing composition further comprises a buffer.

19. The polishing composition according to claim 18, wherein the buffer is selected from ammonium salts, alkali metal salts, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, amino acids, and combinations thereof.

20. A method for chemically and mechanically polishing a substrate, comprising: (i) Providing a substrate comprising a boron-doped polycrystalline silicon layer. (ii) Provide polishing pads (iii) Providing a chemical mechanical polishing composition, the chemical mechanical polishing composition comprising: (a) about 0.001 wt.% to about 10 wt.% of titanium oxide abrasive, wherein the titanium oxide abrasive is substantially pure rutile titanium oxide; (b) Oxidizing agents; and (c) Water, The chemimechanical polishing composition described herein has a pH of about 7 or lower. (iv) Contact the substrate with the polishing pad and the chemical mechanical polishing composition, and (v) Moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to grind at least a portion of the substrate, thereby polishing the substrate.

21. The method of claim 20, wherein the titanium oxide abrasive has an average particle size of about 10 nm to about 300 nm.

22. The method of claim 20, wherein the oxidant is selected from potassium persulfate, cerium ammonium nitrate, peroxide, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, and combinations thereof.

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