Compositions and methods for selective oxide CMP

Abstract

A chemical mechanical polishing composition for polishing a substrate having a silicon-oxygen material includes a liquid carrier, cubic abrasive particles dispersed in the liquid carrier, and at least one of an anionic compound and a nonionic compound.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Application No. 62 / 924,352, entitled "Composition and Method for Selective Oxide CMP," filed on 22 October 2019. [Background technology]

[0002] Chemical mechanical polishing (CMP) is an important enabling technique in the fabrication of integrated circuits (ICs) and microelectromechanical systems (MEMS). CMP compositions and methods for polishing (or planarizing) the surface of substrates (e.g., wafers) are well known to those skilled in the art. Polishing compositions (also known as polishing slurry, CMP slurry, and CMP composition) generally contain abrasive particles suspended (dispersed) in an aqueous solution to increase the material removal rate, improve planarization efficiency, and / or reduce the defect rate during CMP operations.

[0003] Cerium oxide (ceria) abrasives are well known in this industry for polishing silicon-containing substrates, specifically silicon oxide materials such as tetraethyl orthosilicate (TEOS), silicon nitride, and / or polysilicon. Ceria abrasive compositions are widely used in advanced dielectric applications, including shallow trench isolation applications. Although the use of ceria abrasives is known, there is still a need for improved ceria abrasive-based CMP compositions. Specifically, there is still a need for CMP compositions that improve removal rate and planarization (e.g., reducing erosion and dishing). Furthermore, there is still a need for removal rate selectivity of one silicon-containing material compared to another silicon-containing material (e.g., selectivity of silicon oxide to silicon nitride, or selectivity of silicon oxide to polysilicon). [Overview of the project] [Means for solving the problem]

[0004] A chemical mechanical polishing composition for polishing substrates having a silicon-oxygen material (e.g., silicon oxide) is disclosed. In one embodiment, the polishing composition comprises, or essentially comprises, a liquid carrier, cubic abrasive particles dispersed in the liquid carrier, and at least one of an anionic compound and a nonionic compound.

[0005] To gain a more complete understanding of the disclosed subject matter and its merits, it will be described in detail below, along with the attached drawings. [Brief explanation of the drawing]

[0006] [Figure 1] Figures 1 and 2 are transmission electron microscope (TEM) images of cubic ceria abrasive samples showing ceria abrasive particles with square faces. [Figure 2] Figures 1 and 2 are transmission electron microscope (TEM) images of cubic ceria abrasive samples showing ceria abrasive particles with square faces. [Figure 3] Figure 3 is a scanning electron microscope (SEM) image of a cubic ceria abrasive sample showing ceria abrasive particles with square faces. [Modes for carrying out the invention]

[0007] Chemical mechanical polishing compositions for polishing substrates having a silicon-oxygen material (e.g., silicon oxide) are disclosed. The polishing composition comprises, or essentially comprises, a liquid carrier, cubic abrasive particles dispersed in the liquid carrier, and at least one of an anionic compound and a nonionic compound. In one embodiment, the polishing composition comprises an anionic polymer, e.g., poly(acrylic acid), poly(methacrylic acid), and / or poly(vinyl sulfonic acid). In another embodiment, the polishing composition comprises a nonpolymeric anionic compound, e.g., 4-dodecylbenzenesulfonic acid. In yet another embodiment, the polishing composition comprises a nonionic polymer, e.g., polyvinylpyrrolidone or poly(vinylpyrrolidone-co-vinyl acetate).

[0008] The disclosed polishing compositions and corresponding (CMP methods) can yield significant and unexpected advantages. For example, the disclosed compositions can significantly improve the silicon oxide removal rate, thereby improving the processing volume and saving time and cost. The disclosed compositions can further improve selectivity for silicon nitride layers and / or polysilicon layers, thereby providing greater process flexibility.

[0009] The abrasive composition contains abrasive particles, including cubic ceria abrasive particles suspended in a liquid carrier. “Cubic” means that the ceria abrasive particles have a cubic form or shape, i.e., are approximately cubic. In other words, cubic ceria abrasive particles are cubic in shape and properties. However, it goes without saying that the edge dimensions, corners, and corner angles do not need to be exactly or precisely cubic. For example, cubic abrasive particles may have slightly rounded or missing corners, slightly rounded edges, edge dimensions that are not exactly equal to each other, corner angles that are not exactly 90 degrees, and / or minor irregularities, while still maintaining the basic cubic shape. As will be readily apparent to those skilled in the art (e.g., via scanning electron microscopy or transmission electron microscopy), cubic ceria abrasive particles generally have a cubic shape with tolerances allowed for particle growth and deaglomeration.

[0010] Figures 1, 2, and 3 show examples of cubic ceria abrasive particles. These transmission electron microscopy (TEM) and SEM images show ceria abrasive particles having square faces. For example, in these images, each shown particle face contains four edges of approximately the same length (e.g., within 20% of each other, or within 10% of each other, or less). Furthermore, the edges merge at the corners at an angle of approximately 90 degrees (e.g., in the range of about 80–100 degrees, or in the range of about 85–95 degrees). As will be apparent to those skilled in the art, the TEM and SEM images show that the majority of the shown abrasive particles are cubic in that they have the square faces defined above. Some particles can be observed to have defects, for example, on one or more corners. Again, the term cubic is not intended to describe ceria abrasive particles that are exactly cubes, but rather particles that are essentially roughly cubic as defined above and shown in Figures 1, 2, and 3.

[0011] The chemical mechanical abrasive compositions used herein, comprising cubic ceria abrasives, are such that at least 25 percent of the abrasive particles are essentially cubic (cubic in form or shape as described above). In preferred embodiments, at least 40 percent (e.g., at least 60 percent, or at least 80 percent) of the abrasive particles are essentially cubic. As described above, cubic ceria abrasive particles can be easily evaluated and counted using TEM or SEM imaging at magnifications, for example, about 10,000x to about 500,000x. The abrasive particles shown in the SEM or TEM images have faces with four sides of similar length (e.g., within 20 percent of each other). The images also show that adjacent sides are nearly perpendicular, forming an angle of, for example, about 90 degrees (e.g., in the range of about 80 to 100 degrees). To determine whether a ceria abrasive composition contains cubic ceria abrasive particles, a statistical analysis shall be performed, and a large number of randomly selected particles (i.e., 200 or more) shall be observed by SEM or TEM to determine the percentage of particles with square faces. The retained particles must be such that their images are clearly visible on a microscope. Some particles may exhibit some defects on one or more of their surfaces and / or corners, but they can still be counted as cubic.

[0012] The cubic ceria abrasive particles may be substantially pure ceria abrasive particles (within the usual tolerance for impurities) or doped ceria abrasive particles. The doped ceria abrasive particles may contain interstitial dopants (dopants that occupy spaces in the lattice that are not normally occupied) or substitutional dopants (dopants that occupy spaces in the lattice that are normally occupied by cerium or oxygen atoms). Such dopants may contain substantially any metal atom, including, for example, Ca, Mg, Zn, Zr, Sc, or Y.

[0013] In certain advantageous embodiments, the dopant may comprise one or more lanthanides, including, for example, lanthanum, praseodymium, neodymium, promethium, samarium, and similar. In one particularly preferred embodiment, the cubic ceria abrasive particles comprise a mixed oxide of cerium and lanthanum. The molar ratio of La to (La+Ce) in the mixed oxide abrasive particles may be about 0.01 to about 0.15, for example, about 0.01 to about 0.12. Needless to say, such abrasive particles may also contain other elements and / or oxides (e.g., as impurities). Such impurities may originate from the raw materials or starting materials used in the preparation process of the abrasive particles. Preferably, the total proportion of impurities is less than 0.2% by mass of the particles. Residual nitrates are not considered impurities.

[0014] In certain embodiments, the molar ratio of La to (La+Ce) may be about 0.01 to about 0.04 (e.g., about 0.02 to about 0.03). In one such embodiment, the cubic ceria abrasive particles contain about 2.5 mol% lanthanum oxide and about 97.5 mol% cerium oxide. In other embodiments, the molar ratio may be about 0.08 to about 0.12 (e.g., about 0.09 to about 0.11). In one other such embodiment, the cubic ceria abrasive particles contain about 10 mol% lanthanum oxide and about 90 mol% cerium oxide. The abrasive particles may be a single-phase solid solution in which lanthanum atoms substitute for cerium atoms in the cerium oxide crystal structure. In one embodiment, the solid solution exhibits a symmetrical X-ray diffraction pattern, in which case the peak is located between about 27 and about 29 degrees, shifted to a smaller angle than that of pure cerium oxide. A solid solution can be obtained when the temperature of the aging sub-step (described later) is higher than approximately 60°C. As used herein, the term “solid solution” means that X-ray diffraction shows only the pattern of the cerium oxide crystal structure, regardless of the presence or absence of shifts in individual peaks, but without additional peaks indicating the presence of other phases.

[0015] Cubic ceria abrasive particles can optionally be characterized by their specific surface area, determined on a powder by nitrogen adsorption using the Brunauer-Emmett-Teller (BET) method. This method is disclosed in ASTM D3663-03 (re-approved in 2015). The specific surface area of ​​the abrasive particles is approximately 3 to 14 m². 2 / g (for example, approximately 7 to 13m) 2 / g, or approximately 8 to 12m 2 / g) is acceptable.

[0016] Cubic ceria abrasive particles may optionally be characterized by their average particle size and / or particle size distribution. The average particle size of the abrasive particles may be about 50 nm to about 1000 nm (e.g., about 80 nm to about 500 nm, about 80 nm to about 250 nm, about 100 nm to about 250 nm, or about 150 nm to about 250 nm). Furthermore, the average particle size may be greater than about 50 nm (e.g., greater than about 80 nm or greater than about 100 nm). The average particle size can be determined via dynamic light scattering (DLS), which corresponds to the median particle size (D50). DLS measurements can be performed using, for example, a Zetasizer (available from Malvern Instruments). As will be apparent to those skilled in the art, DLS measurements can significantly undercount smaller particles when measured in the presence of relatively larger particles. With respect to the cubic ceria abrasive particles disclosed herein, DLS techniques tend to undercount particles smaller than about 40 nm. Needless to say, the disclosed embodiments may contain a large number of such small particles (less than 40 nm) that are not counted by DLS and therefore do not contribute to the average particle size.

[0017] Laser diffraction techniques can also be optionally used to characterize the particle size distribution. As will be apparent to those skilled in the art, laser diffraction techniques also tend to undercount small particles (e.g., less than about 40 nm in the disclosed embodiments). Laser diffraction measurements can be performed, for example, using a Horiba LA-960 with a relative refractive index of 1.7. From the distribution obtained by laser diffraction measurement, various parameters can be obtained, including, for example, D10, D50, D90, D99, and the dispersion index (defined below). Based on the laser diffraction measurement, the abrasive particles may include a median diameter (D50) of about 100 nm to about 700 nm (e.g., about 100 nm to about 200 nm). For example, D50 may be about 100 nm to about 150 nm or about 150 nm to about 200 nm. D50 is the median diameter determined from the distribution obtained by laser diffraction.

[0018] Optionally, the D10 of the cubic ceria abrasive particles may be about 80 nm to about 400 nm (e.g., about 80 nm to about 250 nm, about 80 nm to about 150 nm, or about 100 nm to about 130 nm). Needless to say, D10 is the particle size obtained by laser diffraction, and is that particle size at which 10% of the particles have a diameter less than D10.

[0019] Optionally, the D90 of the cubic ceria abrasive particles may be about 150 nm to about 1200 nm (e.g., about 150 nm to about 1000 nm, about 150 to about 750 nm, about 150 to about 500 nm, about <150 to about 300 nm, or about 200 nm to about 300 nm). D90 is the particle size obtained by laser diffraction, and represents that particle size at which 90% of the particles have a diameter less than D90. The D90 of the abrasive particles subjected to mechanical deagglomeration may be less than about 300 nm.

[0020] Optionally, the cubic ceria abrasive particles can exhibit a low dispersion index. The "dispersion index" is given by the following formula: Dispersion index = (D90 - D10) / 2·D50 It is defined by. The dispersion index may be less than about 0.60, for example less than about 0.5, less than about 0.4, or less than about 0.30. The dispersion index of the mechanically deagglomerated abrasive particles may be less than about 0.30. Further, D90 / D50 may be about 1.3 to about 2 for the particles subjected to mechanical deagglomeration.

[0021] Optionally, D99 of the cubic ceria abrasive particles is about 150 nm to about 3000 nm (e.g., about 200 nm to about 2000 nm, about 200 nm to about 1800 nm, about 200 to about 1200, about 200 to about 900, about 200 nm to about 600 nm, about 200 to about 500 nm, or about 200 to about 400 nm). The D99 of the mechanically deagglomerated abrasive particles may be less than about 600 nm (e.g., less than about 500 or less than about 400). D99 is the particle size obtained by laser diffraction and represents the particle size at which 99% of the particles have a diameter less than D99.

[0022] The abrasive particles can be prepared using substantially any suitable method suitable for producing cubic ceria abrasive particles. The disclosed embodiments relate to a chemical mechanical polishing composition containing such abrasive particles and a method of polishing a substrate using such abrasive particles, and are not limited to any particular particle production method. In certain embodiments, the cubic ceria abrasive particles may be prepared by precipitating cerium nitrate (and optionally other nitrates if a doped ceria abrasive is prepared). The growth of the cubic ceria abrasive particles can be promoted by growing the precipitated material in a specific temperature-pressure regime. These particles can then be purified and subjected to a deagglomeration treatment. A dispersion of the cubic ceria abrasive particles can then be prepared and used to formulate the chemical mechanical composition of the present invention.

[0023] In one advantageous embodiment, cubic cerium lanthanum oxide abrasive particles can be prepared by precipitating nitrates of cerium and lanthanum. One such preparation method is the following steps, namely, (i) A step of mixing an aqueous solution of cerium nitrate and an aqueous base under an inert atmosphere, (ii) A step of heating the mixture obtained in (i) under an inert atmosphere, (iii) Optionally, a step of acidifying the heat-treated mixture obtained in (ii), (iv) A step of washing the solid material obtained in (ii) or (iii) with water, (v)(iv) The solid material obtained in (v)(iv) is mechanically processed to deaglomerate the ceria particles. Includes.

[0024] The cerium nitrate solution used in step (i) of the above method can be prepared by mixing an aqueous solution of cerium nitrate and lanthanum nitrate. This aqueous solution contains Ce III Ce IV and La III This includes Ce relative to total Ce IV It can be characterized by a molar ratio of approximately 1 / (500,000) to approximately 1 / (4,000). In one embodiment, this molar ratio may be approximately 1 / (100,000) to approximately 1 / (90,000). It is generally advantageous to use salts and components with high purity, for example, at least 99.5 mass percent or 99.9 mass percent.

[0025] Step (i) includes mixing / reacting an aqueous solution of cerium nitrate with an aqueous base. Hydroxide-type bases, such as alkali metal or alkaline earth metal hydroxides and aqueous ammonia, may be advantageous. Secondary, tertiary, or quaternary amines may be used. The aqueous solution of the base may be pre-degassed (deoxygenated) by foaming with an inert gas. Mixing can be carried out by introducing the aqueous solution of cerium nitrate into the aqueous base. Mixing is carried out under an inert atmosphere, for example in a closed or semi-closed reactor with purging of an inert gas (e.g., nitrogen or argon). Mixing may be carried out with stirring. The molar ratio of the base to (Ce+La) may be about 8.0 to about 30.0 (e.g., greater than about 9.0). Step (i) may further be carried out at a temperature of 5°C to about 50°C, for example, about 20°C to 25°C.

[0026] Step (ii) includes heating the mixture obtained at the end of the preceding step and may include a heating sub-step and an aging sub-step. The heating sub-step may include heating the mixture to a temperature of 75°C to about 95°C, for example, about 85°C to about 90°C. The aging sub-step may include maintaining (holding) the mixture at that temperature for about 2 hours to about 20 hours. Generally, the aging time decreases as the temperature increases. Step (ii) can also be carried out with stirring under an inert atmosphere, as described above with respect to step (i).

[0027] In step (iii), the mixture obtained at the end of step (ii) can optionally be acidified using, for example, nitric acid. The heat-treated reaction mixture can be acidified to a pH of, for example, less than about 3.0 (e.g., about 1.5 to about 2.5).

[0028] In step (iv), the solid material obtained in step (ii) or (iii) may be washed with water (e.g., deionized water). Washing reduces residual nitrates in the final dispersion and allows the target conductivity to be obtained. Washing may include filtering the solids from the mixture and then redispersing the solids in water. Filtration and redispersion may be carried out several times if necessary.

[0029] In step (v), the washed solid material obtained in (iv) can be optionally mechanically treated to deaglomerate or partially deaglomerate the ceria abrasive particles. Mechanical treatment includes, for example, double-jet treatment or ultrasonic deaglomeration, which typically results in a narrow particle size distribution and reduces the number of large aggregated particles.

[0030] After step (iv) or (v), the solid material can be dried to obtain cerium-based particles in powder form. By adding water or a mixture of water and a miscible liquid organic compound, the powder can be redispersed to obtain a dispersion of cerium-based particles in a liquid medium. The liquid medium may be water or a mixture of water and a water-miscible organic liquid. The water-miscible organic liquid may include, for example, alcohols such as isopropyl alcohol, ethanol, 1-propanol, methanol, 1-hexanol, ketones such as acetone, diacetone alcohol, methyl ethyl ketone, esters such as ethyl formate, propyl formate, ethyl acetate, methyl acetate, methyl lactate, butyl lactate, and ethyl lactate. The ratio of water to organic liquid may be 80:20 to 99:1 parts by mass. Furthermore, the dispersion may contain about 1% to about 40% by mass, for example, about 10% to about 35% by mass, of cerium-based particles. The dispersion may also have an conductivity of less than about 300 μS / cm, for example less than about 150 μS / cm, more specifically less than 150 μS / cm, or less than about 100 μS / cm.

[0031] The abrasive composition may contain substantially any appropriate amount of cubic ceria abrasive particles. For example, the abrasive composition may contain about 0.001 mass percent or more (e.g., about 0.005 mass percent or more, about 0.01 mass percent or more, about 0.02 mass percent or more, about 0.05 mass percent or more, or about 0.1 mass percent or more) of cubic ceria abrasive particles at the point of use. The abrasive composition may contain about 5 mass percent or less (e.g., about 2 mass percent or less, about 1.5 mass percent or less, or about 1 mass percent or less) of cubic ceria abrasive particles at the point of use. Needless to say, the cubic ceria abrasive particles may be present in the abrasive composition at concentrations separated by any two of the aforementioned endpoints. For example, the concentration of cubic ceria abrasive particles in the abrasive composition may be about 0.001% by mass to about 5% by mass at the point of use (e.g., about 0.01% by mass to about 2% by mass, about 0.05% by mass to about 1.5% by mass, or about 0.1% by mass to about 1% by mass).

[0032] An aqueous liquid carrier is used to facilitate the application of abrasives and any optional chemical additives to the surface of a substrate to be polished (e.g., planarized). Aqueous means that the liquid carrier consists of at least 50 wt% water (e.g., deionized water). The liquid carrier may also contain other suitable non-aqueous carriers, including lower alcohols (e.g., methanol, ethanol, etc.) and ethers (e.g., dioxane, tetrahydrofuran, etc.). Preferably, the liquid carrier consists essentially of or is derived from water, more preferably from deionized water.

[0033] The abrasive composition is generally weakly acidic, neutral, or alkaline, and has a pH of about 4 to about 11. For example, the pH of the abrasive composition may be about 5 to about 10. In one embodiment, the abrasive composition is weakly acidic and has a pH of about 4 to about 7 (e.g., about 4 to about 6, or about 4.5 to about 6). For example, in such a weakly acidic embodiment, the pH may be about 5. In another embodiment, the abrasive composition is alkaline and has a pH of about 8 to about 11 (e.g., about 9 to about 11, or about 9 to about 10.5, or about 9.5 to about 10.5). For example, in such an alkaline embodiment, the pH may be about 10. In yet another embodiment, the abrasive composition is neutral and has a pH of about 6 to about 8 (e.g., about 6.5 to about 7.5).

[0034] The polishing composition may further contain chemical additives. The chemical additives interact with the surface of the cubic ceria abrasive particles and / or with the surface of the substrate being polished (e.g., via electrostatic interactions and / or hydrogen bonding). The chemical additives may be, for example, dispersants, rheological agents, polishing rate accelerators, polishing rate inhibitors, or selectivity enhancers (to improve the removal rate ratio of one material to another). Preferred chemical additives include anionic compounds (e.g., anionic polymers and anionic surfactants) and nonionic compounds, such as nonionic polymers.

[0035] Suitable anionic compounds may include anionic polymers and nonpolymeric anionic compounds (e.g., surfactants). Anionic compounds may include water-soluble polymer electrolytes, polyanions, polyacids, polyacrylates, poly(vinyl acid), anionic detergents, alkyl or alkyl ether sulfonates and sulfates, alkyl or alkyl ether phosphonates and phosphates, and alkyl or alkyl ether carboxylates.

[0036] Anionic polymers are homopolymers or copolymers and may contain monomer units selected from carboxylic acid groups, sulfate or sulfonic acid groups, and phosphate or phosphonic acid groups. Suitable anionic polymers may include poly(acrylic acid), poly(methacrylic acid), poly(maleic acid), poly(vinyl sulfonic acid), poly(styrene sulfonic acid), poly(vinyl sulfate), poly(vinyl phosphoric acid), poly(2-acrylamido-2-methyl-1-propanesulfonic acid), and combinations thereof. Anionic compounds may also include sodium and ammonium salt versions of the above compounds (e.g., poly(methacrylic acid, sodium salt)). Anionic compounds may also include derivatives of the above compounds. For example, in these derivatives, one or more alkyl groups or other functional groups are included in the compound. For example, poly(methacrylic acid) is a derivative of poly(acrylic acid).

[0037] Examples of anionic polymers may further include copolymers comprising one or more of the following monomers: acrylic acid, methacrylic acid, maleic acid, vinyl sulfonic acid, sulfate, styrene sulfonic acid, and phosphate monomers. Such anionic polymers may optionally contain one or more nonionic monomers. Nonionic monomers include, but are not limited to, methacrylate esters, vinyl acetate, acrylamide, and N-vinylpyrrolidone. Examples of copolymers may include poly(methyl methacrylate-co-methacrylic acid), poly(acrylamide-co-acrylic acid), poly(4-styrene sulfonic acid-co-maleic acid), and poly(acrylic acid-co-maleic acid).

[0038] Nonpolymeric anionic compounds may include alkyl or alkylaryl sulfates, alkyl or alkylaryl sulfonates, alkyl or alkylaryl phosphates, alkyl or alkylaryl carboxylates, or combinations thereof. Examples of anionic compounds include dodecylbenzenesulfonic acid, ammonium lauryl sulfate, 1-decanesulfonate, stearic acid, dihexadecyl phosphate, dodecylphosphonic acid, and combinations thereof, their ammonium and sodium salt versions, and their derivatives.

[0039] Suitable nonionic compounds may include water-soluble nonionic polymers and nonpolymeric nonionic compounds. Nonionic compounds may include water-soluble polyethers, polyether glycols, alcohol ethoxylates, polyoxyalkylene alkyl ethers, polyesters, vinyl acrylates, or combinations thereof.

[0040] The nonionic polymer may be a homopolymer or a copolymer and may contain substantially any suitable nonionic monomer units. Examples of nonionic polymers include polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl formal, polyvinyl butyral, polyvinylpyrrolidone, poly(vinylphenyl ketone), poly(vinylpyridine), poly(vinylimidazole), poly(acrylamide), polyacrolein, poly(methylmethacrylic acid), polyethylene, polyoxyethylene lauryl ether, polyhydroxyethyl methacrylate, poly(ethylene glycol) monolaurate, poly(ethylene glycol) monooleate, poly(ethylene glycol) distearate, and copolymers containing one or more of the aforementioned monomer units. Examples of copolymers include poly(vinyl acetate-co-methyl methacrylate), poly(vinylpyrrolidone-co-vinyl acetate), and poly(ethylene-co-vinyl acetate).

[0041] Nonionic compounds may include derivatives of the compounds described above. For example, these derivatives may contain one or more alkyl groups or other functional groups. For example, poly(N-isopropylacrylamide) is a derivative of poly(acrylamide).

[0042] The abrasive composition may contain substantially any appropriate amount of anionic and / or nonionic compounds. For example, the abrasive composition may contain about 100 ppm (0.01% by mass) or more (e.g., about 250 ppm or more, about 500 ppm or more, about 750 ppm or more, or about 1000 ppm (0.1% by mass) or more) of anionic and / or nonionic compounds at the point of use. The abrasive composition may contain about 2% or less (e.g., about 1.5% or less, about 1.2% or less, or about 1% or less) of anionic and / or nonionic compounds at the point of use. Needless to say, the anionic and / or nonionic compounds may be present in the abrasive composition at concentrations separated by any two of the aforementioned endpoints. For example, the concentration of anionic and / or nonionic compounds in the abrasive composition may be about 0.01% to about 2% by mass (about 0.05% to about 1.5% by mass, or about 0.1% to about 1% by mass) at the point of use.

[0043] The polishing composition may further contain any other optional additives, such as secondary polishing rate accelerators or inhibitors, dispersants, conditioners, scale inhibitors, chelating agents, stabilizers, pH adjusters / buffering compounds, and biocides. Such additives are purely optional. The disclosed embodiments are not limited in that sense and do not require the use of any one or more of such additives.

[0044] The abrasive composition may optionally further contain a biocide. The biocide may be substantially any suitable biocide, such as an isothiazolinone biocide, such as methylisothiazolinone or benzisothiazolon. The amount of biocide in the abrasive composition is typically about 1 ppm by mass to about 100 ppm by mass at the point of use, for example, about 5 ppm by mass to about 75 ppm by mass.

[0045] Polishing compositions can be prepared using any appropriate technique. Many of these techniques are known to those skilled in the art. Polishing compositions can be prepared by batch or continuous methods. Broadly speaking, polishing compositions can be prepared by combining their components in any order. As used herein, “component” includes individual components (e.g., abrasive particles, anionic and / or nonionic compounds, and any additives). For example, anionic and / or nonionic compounds can be added to an aqueous carrier (e.g., water) at a desired concentration. The pH can then be adjusted (as desired), and cubic ceria abrasives can be added at a desired concentration to form a polishing composition. Polishing compositions can be prepared immediately before use, in which case one or more components are added to the polishing composition immediately before use (e.g., within about 1 minute before use, or within about 1 hour before use, or about 1 day or about 7 days before use). Polishing compositions can also be prepared by mixing the components on the substrate surface during polishing (e.g., on a polishing pad).

[0046] In certain embodiments, the polishing composition can be provided as a "two-pack" system. For example, the first pack may contain cubic ceria abrasive and other optional components, and the second pack may contain an anionic and / or nonionic compound and yet other optional components. The first and second packs are shipped separately and can be combined on the polishing pad before polishing (within one hour or one day of polishing) or during CMP work.

[0047] The abrasive composition of the present invention may be provided as a concentrate. The concentrate is intended to be diluted with an appropriate amount of water before use. In such embodiments, the abrasive composition concentrate may contain cubic ceria abrasive particles and the other components described above in such amounts that, when the concentrate is diluted with an appropriate amount of water, each component of the abrasive composition is present in the abrasive composition in the appropriate range described above with respect to each component. For example, cubic ceria abrasive particles, auto-stoppers, cationic polymers, and any other optional additives can each be present in the abrasive composition in amounts approximately three times (e.g., approximately four times, five times, six times, seven times, eight times, ten times, fifteen times, twenty times, or twenty-five times) the use point concentration described above for each component. Therefore, when the concentrate is diluted with equal volumes (e.g., two equal volumes of water, three equal volumes of water, four equal volumes of water, five equal volumes of water, six equal volumes of water, seven equal volumes of water, nine equal volumes of water, fourteen equal volumes of water, nineteen equal volumes of water, or twenty-four equal volumes of water), each component will be present in the abrasive composition in amounts within the range described above for each component.

[0048] In embodiments where the abrasive composition is provided as a two-pack system, one or both packs are provided as concentrates requiring dilution before mixing with the other pack. For example, in one embodiment, the first pack is provided as a concentrate containing cubic ceria abrasive particles at a concentration approximately three times (e.g., approximately five times, eight times, ten times, fifteen times, or twenty times) higher than the above-mentioned point of use concentration. The concentrated first pack can be mixed with an appropriate amount of water before combining with the second pack. Similarly, the second pack is also provided as a concentrate containing anionic and / or nonionic compounds at a concentration approximately three times (e.g., approximately five times, eight times, ten times, fifteen times, or twenty times) higher than the above-mentioned point of use concentration. In such embodiments, the concentrated second pack can be mixed with an appropriate amount of water before combining with the first pack. In certain embodiments, both the first and second packs can be diluted with water before combining. The disclosed embodiments are not limited to these.

[0049] The polishing method of the present invention is particularly suitable for use in conjunction with a chemical mechanical polishing (CMP) apparatus, for example, one that includes a platen and a pad fixed to the platen. As is known to those skilled in the art, polishing is performed on a substrate when it is brought into contact with a polishing pad and the polishing composition of the present invention, and then at least a portion of the substrate is ground by moving the polishing pad and the substrate in relative motion. The method of the present invention involves preparing the above-mentioned composition of the present invention, bringing a substrate (e.g., a wafer) into contact with the polishing composition of the present invention, moving the polishing composition relative to the substrate, and grinding the substrate to remove a portion of the silicon oxide material from the substrate, thereby polishing the substrate.

[0050] Broadly speaking, the substrate contains a patterned dielectric layer, many of which are well known. The patterned dielectric layer contains various forms of silicon oxide and silicon oxide-based dielectric materials. For example, dielectric materials containing silicon oxide and silicon oxide-based dielectric layers include, or essentially consist of, tetraethyl orthosilicate (TEOS), high-density plasma (HDP) oxides, phosphatesilicate glass (PSG), borosilicate glass (BPSG), high-aspect-ratio process (HARP) oxides, spin-on dielectric (SOD) oxides, chemical vapor deposition (CVD) oxides, plasma-assisted tetraethyl orthosilicate (PETEOS), thermal oxides, or undoped silicate glasses.

[0051] The polishing composition can preferably exhibit a high removal rate when polishing substrates containing silicon oxide materials. For example, when polishing silicon wafers containing high-density plasma (HDP) oxide and / or plasma-assisted tetraethyl orthosilicate (PETEOS), spin-on glass (SOG), and / or tetraethyl orthosilicate (TEOS), the polishing composition can preferably exhibit a silicon oxide removal rate of about 1000 Å / min or more (e.g., about 2000 Å / min or more, about 2500 Å / min or more, about 3000 Å / min or more, about 3500 Å / min or more, about 4000 Å / min or more, about 4500 Å / min or more, or about 5000 Å / min or more).

[0052] The polishing composition may also be suitable for polishing substrates containing both silicon oxide and silicon nitride materials. In certain embodiments, it may be desirable that the removal rate of the silicon oxide material exceeds the removal rate of the silicon nitride material (i.e., the removal rate selectivity of silicon oxide to silicon nitride is greater than 1). In examples of embodiments, it is advantageous for the polishing composition to exhibit a removal rate selectivity of silicon oxide to silicon nitride greater than 2 (for example, greater than 3, greater than 5, greater than 7, greater than 10, greater than 15, greater than 20 in certain embodiments).

[0053] In other applications where an abrasive composition is used to polish both silicon oxide and silicon nitride materials, it may be desirable that the removal rate of the silicon nitride material exceeds that of the silicon oxide material. In an example of the embodiment, it may be advantageous for the abrasive composition to exhibit a selectivity of silicon nitride to silicon oxide greater than 1 (i.e., a selectivity of silicon oxide to silicon nitride less than 1).

[0054] The polishing composition may also be suitable for polishing substrates containing both silicon dioxide and polysilicon materials. In certain embodiments, it may be desirable that the removal rate of the silicon dioxide material exceeds the removal rate of the polysilicon (i.e., the removal rate selectivity of silicon dioxide relative to polysilicon is greater than 1). In examples of embodiments, it is advantageous for the polishing composition to exhibit a removal rate selectivity of silicon dioxide relative to polysilicon of greater than 2 (for example, greater than 3, greater than 5, greater than 7, greater than 10, greater than 15, greater than 20 in certain embodiments).

[0055] The method of the present invention desirablely planarizes patterned dielectric material by, for example, reducing the initial step height between a raised region (having an initial height) and a trench (having an initial trench thickness). To achieve this planarization effectively and efficiently, the method of the present invention preferably has a high removal rate of the raised region (of the active patterned dielectric material) and a relatively low removal rate of the dielectric material in the trench. As polishing progresses, the wafer is planarized by reducing the step height between the raised region and the trench.

[0056] Needless to say, the disclosure includes numerous embodiments. These embodiments include, but are not limited to, the following embodiments.

[0057] In a first embodiment, the chemical mechanical polishing composition includes a liquid carrier, cubic abrasive particles dispersed in the liquid carrier, and at least one of an anionic compound and a nonionic compound.

[0058] A second embodiment may include the first embodiment, and the cubic ceria abrasive particles include a mixture of cerium oxide and lanthanum oxide.

[0059] A third embodiment may include any one of the first to second embodiments, and the molar ratio of lanthanum to lanthanum and cerium in the cubic ceria abrasive particles is about 1 to about 15 percent.

[0060] A fourth embodiment may include any one of the first to third embodiments, and the BET surface area of the cubic ceria abrasive particles is about 3 m 2 / g to about 14 m 2 / g.

[0061] A fifth embodiment may include any one of the first to fourth embodiments, and the average particle size of the cubic ceria abrasive particles is about 50 to about 500 nm.

[0062] A sixth embodiment may include any one of the first to fifth embodiments, and includes cubic ceria abrasive particles of about 0.01 to about 2 mass percent at the use point.

[0063] The seventh embodiment may include any one of the first to sixth embodiments, wherein the anionic compound includes water-soluble polymer electrolytes, polyanions, polyacids, polyacrylates, poly(vinyl acid), anionic detergents, alkyl or alkyl ether sulfonates and sulfates, alkyl or alkyl ether phosphonates and phosphates, and alkyl or alkyl ether carboxylates.

[0064] The eighth embodiment may include any one of the first to seventh embodiments, wherein the anionic compound is an anionic homopolymer or copolymer and comprises at least one monomer unit selected from acrylic acid, methacrylic acid, maleic acid, vinyl sulfonic acid, sulfate, styrene sulfonic acid, and phosphate.

[0065] The ninth embodiment may include any one of the first to eighth embodiments, wherein the anionic compound includes poly(acrylic acid), poly(methacrylic acid), poly(maleic acid), poly(vinyl sulfonic acid), poly(styrene sulfonic acid), poly(vinyl sulfate), poly(2-acrylamido-2-methyl-1-propanesulfonic acid), poly(vinyl phosphoric acid), poly(methyl methacrylate-co-methacrylic acid), poly(acrylic acid-co-maleic acid), poly(acrylamido-co-acrylic acid), poly(4-styrene sulfonic acid-co-maleic acid), or a combination thereof.

[0066] The tenth embodiment may include any one of the first to ninth embodiments, wherein the anionic compound is a nonpolymer compound and comprises an alkyl or alkylaryl sulfate, an alkyl or alkylaryl sulfonate, an alkyl or alkylaryl phosphate, an alkyl or alkylaryl carboxylate, or a combination thereof.

[0067] The eleventh embodiment may include any one of the first to tenth embodiments, wherein the anionic compound is dodecylbenzenesulfonic acid, ammonium lauryl sulfate, stearic acid, dihexaphosphate, dodecyl phosphate, 1-decanesulfonate, derivatives thereof, ammonium or sodium salts thereof, or a combination thereof.

[0068] The twelfth embodiment may include any one of the first to eleventh embodiments, wherein the nonionic compound is a nonionic polymer comprising a water-soluble polyether, polyether glycol, alcohol ethoxylate, polyoxyalkylene alkyl ether, polyester, vinyl acrylate, or a combination thereof.

[0069] The 13th embodiment may include any one of the 1st to 12th embodiments, wherein the nonionic compound is a nonionic homopolymer or copolymer, and includes polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl formal, polyvinyl butyral, polyvinylpyrrolidone, poly(vinylphenyl ketone), poly(vinylpyridine), poly(vinylimidazole), poly(acrylamide), polyacrolein, poly(methylmethacrylic acid), polyethylene, polyoxyethylene lauryl ether, polyhydroxyethyl methacrylate, poly(ethylene glycol) monolaurate, poly(ethylene glycol) monooleate, poly(ethylene glycol) distearate, poly(vinyl acetate-co-methyl methacrylate), poly(vinylpyrrolidone-co-vinyl acetate), poly(ethylene-co-vinyl acetate), and combinations thereof.

[0070] The 14th embodiment may include any one of the 1st to 13th embodiments and may contain about 0.01 mass percent to about 2 mass percent of an anionic or nonionic compound at the point of use.

[0071] The 15th embodiment may include any one of the 1st to 14th embodiments, wherein the pH is approximately 4 to approximately 6, or approximately 9 to approximately 11.

[0072] The 16th embodiment may comprise any one of the 1st to 15th embodiments and comprises, at a use point, about 0.01% to about 2% by mass of cubic ceria abrasive particles, wherein (i) the cubic ceria abrasive particles comprise a mixture of cerium oxide and lanthanum oxide and have an average particle size of about 50 to about 500 nm, (ii) the anionic compound comprises poly(acrylic acid), and (iii) the pH of the composition is about 4 to about 6.

[0073] The 17th embodiment may comprise any one of the 1st to 16th embodiments and comprises, at a use point, about 0.01% to about 2% by mass of cubic ceria abrasive particles, wherein (i) the cubic ceria abrasive particles comprise a mixture of cerium oxide and lanthanum oxide and have an average particle size of about 50 to about 500 nm, (ii) the nonionic compound comprises polyvinylpyrrolidone, poly(vinylpyrrolidone-co-vinyl acetate), or a mixture thereof, and (iii) the pH of the composition is about 9 to about 11.

[0074] The 18th embodiment may include any one of the 1st to 17th embodiments and may contain approximately 0.01 mass percent to approximately 2 mass percent of cubic ceria abrasive particles at the point of use. (i) The cubic ceria abrasive particles contain a mixture of cerium oxide and lanthanum oxide and have an average particle size of about 50 to about 500 nm. (ii) The anionic compound includes poly(methacrylic acid), poly(vinyl sulfonic acid), poly(styrene sulfonic acid), poly(2-acrylamido-2-methyl-1-propanesulfonic acid), poly(4-styrenesulfonic acid-com-maleic acid), dodecylbenzenesulfonic acid, and mixtures thereof, and (iii) The pH of the composition is about 9 to about 11.

[0075] The 19th embodiment includes a method for chemically and mechanically polishing a substrate containing a silicon oxide dielectric material. This method includes (a) preparing one of the first to 18 polishing composition embodiments, (b) bringing the substrate into contact with the prepared polishing composition, (c) moving the polishing composition against the substrate, and (d) ablating the substrate to remove a portion of the silicon oxide dielectric material from the substrate, thereby polishing the substrate.

[0076] The 20th embodiment may include the 19th embodiment, wherein the abrasive composition comprises about 0.01 to 2% by mass of cubic ceria abrasive particles at the point of use, the cubic ceria abrasive particles comprise a mixture of cerium oxide and lanthanum oxide, and have an average particle size of about 50 to about 500 nm, (ii) the anionic compound comprises poly(acrylic acid), (iii) the pH of the abrasive composition is about 4 to about 6, and (iv) during the ablation treatment in (d), the removal rate of the silicon dioxide dielectric material is at least 1000 Å / min.

[0077] The 21st embodiment may include the 20th embodiment, wherein the substrate further comprises at least one of a silicon nitride material and a polysilicon material, and the removal rate selectivity of the silicon oxide dielectric material to the silicon nitride material, or the removal rate selectivity of the silicon oxide dielectric material to the polysilicon material, is greater than about 10:1 in (d).

[0078] The 22nd embodiment may include the 19th embodiment, wherein (i) the abrasive composition comprises about 0.01 to 2% by mass of cubic ceria abrasive particles at the point of use, the cubic ceria abrasive particles comprising a mixture of cerium oxide and lanthanum oxide and having an average particle size of about 50 to about 500 nm, (ii) the nonionic compound comprises polyvinylpyrrolidone, (iii) the pH of the abrasive composition is about 9 to about 11, (iv) the substrate further comprises a silicon nitride material, and (v) the removal rate selectivity of the silicon oxide dielectric material to the silicon nitride material is less than about 1:1 in (d).

[0079] The 23rd embodiment may include the 19th embodiment, wherein (i) the abrasive composition comprises about 0.01 to 2% by mass of cubic ceria abrasive particles at the point of use, the cubic ceria abrasive particles comprising a mixture of cerium oxide and lanthanum oxide, and having an average particle size of about 50 to about 500 nm, (ii) the anionic compound comprises poly(methacrylic acid), poly(vinyl sulfonic acid), poly(styrene sulfonic acid), poly(2-acrylamido-2-methyl-1-propanesulfonic acid), poly(4-styrene sulfonic acid-com-maleic acid), dodecylbenzenesulfonic acid, and mixtures thereof, (iii) the pH of the composition is about 9 to about 11, and (iv) during the ablation treatment in (d), the removal rate of the silicon dioxide dielectric material is at least 3000 Å / min.

[0080] The 24th embodiment may include the 23rd embodiment, wherein the substrate further comprises a silicon nitride material, and the removal rate selectivity of the silicon oxide dielectric material to the silicon nitride material is less than about 10:1 in (d).

[0081] The 25th embodiment may include any one of the 19th to 24th embodiments, wherein preparing the abrasive composition includes preparing an abrasive concentrate and diluting the abrasive concentrate with at least one part of water relative to one part of the abrasive concentrate. [Examples]

[0082] The following examples further illustrate the present invention, but should not be construed as limiting its scope. Various substrates were polished using the Applied Materials Mirra® polishing tool (available from Applied Materials, Inc.). Blanket wafers were polished on the Mirra® for 60 seconds at a platen speed of 100 rpm, head speed of 85 rpm, downforce of 3 psi, and slurry flow rate of 150 ml / min. Wafers were polished on a NexPlanar® E6088 pad (available from Cabot Microelectronics Corporation) by in-situ conditioning with a Saesol DS8051 conditioner with a downforce of 6 pounds.

[0083] Blanket tetraethyl orthosilicate (TEOS), SiN, and polysilicon wafers were polished in the following examples. The TEOS wafers were obtained from WRS Materials and contained a 20 kÅ TEOS layer. The SiN wafers included both SiN PE wafers and SiN LP wafers. The SiN PE wafers were obtained from Advantec and contained a 5 kÅ PE SiN layer. The SiN LP wafers were obtained from Novati and contained a 3 kÅ LP SiN layer. The polysilicon wafers were obtained from WRS Materials and contained a 10 kÅ PolySi layer.

[0084] Example 1 A stock cerium oxide dispersion was prepared as follows: A cerium nitrate solution was prepared by combining 13.1 kg of 3M trivalent cerium(III) nitrate solution, 0.3 kg of 3M lanthanum nitrate solution, 2.0 kg of 68% nitric acid (HNO3) solution, 0.5 kg of deionized water, and cerium(IV) nitrate at a molar ratio of cerium(IV) to total cerium of 0.000055. The cerium nitrate solution was then degassed in a 20 L container by stirring and nitrogen bubbling.

[0085] An aqueous ammonia solution was prepared by combining 75 kg of deionized water with 13.1 kg of a 25% aqueous ammonia solution (resulting in a molar ratio of NH4OH in the aqueous ammonia solution to the total amount of cerium and lanthanum in the cerium nitrate solution of 9.0). The aqueous ammonia solution was then degassed in a 100 L jacketed reactor by stirring and nitrogen bubbling.

[0086] Next, under nitrogen purging and with the same stirring, the cerium nitrate solution was added to the aqueous ammonia solution at ambient temperature. The temperature of the reaction mixture was then raised to 80°C and maintained at that temperature for 18 hours. The reaction mixture was then allowed to cool, and after cooling, the pH was acidified to 2 by adding 68% nitric acid.

[0087] The reaction mixture was then filtered and washed with deionized water. Washing was repeated when the conductivity of the washing solution fell below 0.04 mS / cm. The final cerium oxide concentration was adjusted to 10 mass percent by adding deionized water. The cubic ceria abrasive particles contained 2.5 mole percent lanthanum oxide and 97.5 mole percent cerium oxide.

[0088] Nitrogen adsorption increases the BET specific surface area to 11.3 m². 2 The particle size was determined to be per gram. The average particle size was 102 nm as measured by Horiba 960 and 140 nm as measured by Malvern Zetasizer.

[0089] Example 2 The polishing speeds of TEOS, SiN-PE, SiN-LP, and PolySi were evaluated by testing two polishing compositions. Each composition contained poly(acrylic acid) (approximately 5000 MW) and ceria at pH 4.5. Composition 2A contained a control ceria (commercially available wet-process ceria HC60® from Rhodia), while composition 2B contained the cubic ceria described above in Example 1. The use point concentrations are shown in Table 1A. [Table 1A]

[0090] Under the above conditions, blanket TEOS, SiN-PE, SiN-LP, and PolySi wafers were polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 1B. All removal rates (RR) are expressed in angstroms per minute (Å / min). The selectivity for TEOS:SiN-PE, TEOS:SiN-LP, and TEOS:PolySi is shown in Table 1C. [Table 1B] [Table 1C]

[0091] As is readily apparent from the results shown in Tables 1B and 1C, the TEOS removal rate of composition 2B (containing cubic ceria abrasive) was three times that of composition 2A (containing control ceria), while the removal rates of silicon nitride and polysilicon were similar. As a result, composition 2B exhibited approximately three times higher selectivity for TEOS to SiN and for TEOS to polysilicon than composition 2A.

[0092] Example 3 The polishing rates of TEOS, SiN-PE, SiN-LP, and PolySi were evaluated by testing two types of polishing compositions. Each composition contained poly(methacrylate) sodium salt (approximately 9500 g / mol MW) and ceria at pH 10. Composition 3A contained the control ceria described above in Example 2, while composition 3B contained the cubic ceria described above in Example 1. The use point concentrations are shown in Table 2A. [Table 2A]

[0093] Under the above conditions, blanket TEOS, SiN-PE, SiN-LP, and PolySi wafers were polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 2B. All removal rates (RR) are expressed in angstroms per minute (Å / min). The selectivity for TEOS:SiN-PE, TEOS:SiN-LP, and TEOS:PolySi is shown in Table 2C. [Table 2B] [Table 2C]

[0094] As is readily apparent from the results shown in Tables 2B and 2C, the removal rates of TEOS and SiN in composition 3B (containing cubic ceria abrasive) were unexpectedly about twice as high as those of composition 3A (containing control ceria), while the removal rate of polysilicon was similar. As a result, composition 3B exhibited higher removal rates for both and doubled the selectivity of TEOS for polysilicon compared to composition 3A.

[0095] Example 4 The polishing speeds of TEOS, SiN-PE, SiN-LP, and PolySi were evaluated by testing two types of polishing compositions. Each composition contained poly(vinyl sulfonic acid) and ceria at pH 10. Composition 4A contained the control ceria described above in Example 2, while composition 4B contained the cubic ceria described above in Example 1. The use point concentrations are shown in Table 3A. [Table 3A]

[0096] Under the above conditions, blanket TEOS, SiN-PE, SiN-LP, and PolySi wafers were polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 3B. All removal rates (RR) are expressed in angstroms per minute (Å / min). The selectivity for TEOS:SiN-PE, TEOS:SiN-LP, and TEOS:PolySi is shown in Table 3C. [Table 3B] [Table 3C]

[0097] As is readily apparent from the results shown in Tables 3B and 3C, the TEOS and SiN removal rates of composition 4B (containing cubic ceria abrasive particles) were significantly higher than those of composition 4A (containing control ceria) (TEOS 1.9 times higher, SiN-PE approximately 2.6 times higher, and SiN-LP approximately 1.7 times higher), while the polysilicon removal rate was similar. As a result, composition 4B unexpectedly exhibited increased removal rates for TEOS and SiN, a reduced selectivity of TEOS for SiN-PE, and a 70% increased selectivity of TEOS for polysilicon compared to composition 4A. Furthermore, compositions based on cubic ceria abrasive particles significantly increased the SiN-PE removal rate compared to SiN-LP (150 percent vs. 70 percent).

[0098] Example 5 The polishing rates of TEOS, SiN-PE, SiN-LP, and PolySi were evaluated by testing two types of polishing compositions. Each composition contained 4-dodecylbenzenesulfonic acid and ceria at pH 10. Composition 5A contained the control ceria described above in Example 2, while composition 5B contained the cubic ceria described above in Example 1. The use point concentrations are shown in Table 2A. [Table 4A]

[0099] Under the above conditions, blanket TEOS, SiN-PE, SiN-LP, and PolySi wafers were polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 4B. All removal rates (RR) are expressed in angstroms per minute (Å / min). The selectivity for TEOS:SiN-PE, TEOS:SiN-LP, and TEOS:PolySi is shown in Table 4C. [Table 4B] [Table 4C]

[0100] As is readily apparent from the results shown in Tables 4B and 4C, the removal rates of TEOS and SiN in composition 5B (containing cubic ceria abrasive) were unexpectedly increased (approximately twice and 1.3 times, respectively) compared to composition 5A (containing control ceria), while the removal rate of polysilicon remained similar. As a result, composition 5B unexpectedly showed increased removal rates for TEOS and SiN-LP, and a twofold increase in the selectivity of TEOS for polysilicon compared to composition 5A. Furthermore, the cubic ceria-based composition unexpectedly showed a significantly increased removal rate of SiN-LP compared to SiN-PE (100 percent vs. 25 percent).

[0101] Example 6 The polishing speeds of TEOS, SiN-PE, SiN-LP, and PolySi were evaluated by testing four types of polishing compositions. Each composition contained polyvinylpyrrolidone (PVP) (6A and 6B) or poly(vinylpyrrolidone-co-vinylacetate) (PVP-co-VA) (6C and 6D) and ceria at pH 5. Compositions 6A and 6C contained the control ceria described above in Example 2, while compositions 6B and 6D contained the cubic ceria described above in Example 1. The use point concentrations are shown in Table 5A. [Table 5A]

[0102] Under the above conditions, blanket TEOS, SiN-PE, SiN-LP, and PolySi wafers were polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 5B. All removal rates (RR) are expressed in angstroms per minute (Å / min). The selectivity for TEOS:SiN-PE, TEOS:SiN-LP, and TEOS:PolySi is shown in Table 5C. [Table 5B] [Table 5C]

[0103] As is readily apparent from the results shown in Tables 5B and 5C, composition 6D (containing cubic ceria abrasive and copolymer poly(vinylpyrrolidone-co-vinylacetate)) exhibited higher removal rates for TEOS, SiN, and polysilicon compared to composition 6C (containing control ceria and the same copolymer). However, composition 6B (containing cubic ceria abrasive and homopolymer polyvinylpyrrolidone) showed a TEOS removal rate that was one-quarter of that of composition 6A (containing control ceria and the same homopolymer), a 15% higher removal rate for SiN-PE, and a 25% higher removal rate for SiN-LP. Surprisingly, composition 6B was selective for silicon nitride (selectivity of 2:1 for SiN-PE and TEOS).

[0104] Example 7 The effect of lanthanum doping levels in cubic ceria abrasive particles on TEOS removal rates was evaluated by testing three compositions. Composition 7A contained 0.28 mass percent of control ceria as described in Example 2. Composition 7B contained 0.28 mass percent of cubic ceria abrasive particles containing 2.5 mol percent of lanthanum oxide and was prepared by diluting the stock ceria dispersion described in Example 1 with 34 parts water to 1 part stock ceria dispersion. Composition 7C contained 0.28 mass percent of cubic ceria abrasive particles containing 10 mol percent of lanthanum oxide and was prepared by diluting the ceria dispersion described in the following paragraph with 34 parts water to 1 part ceria dispersion. The pH of each of compositions 7A to 7C was 4.

[0105] A cerium oxide dispersion was prepared as follows: A cerium nitrate solution was prepared by combining 11.5 kg of 3M trivalent cerium(III) nitrate solution, 1.3 kg of 3M lanthanum nitrate solution, 1.86 kg of 68% nitric acid (HNO3) solution, 0.5 kg of deionized water, and cerium(IV) nitrate at a molar ratio of cerium(IV) to total cerium of 0.0000125 (1 / 80,235). The cerium nitrate solution was then degassed in a 20 L container by stirring and nitrogen bubbling.

[0106] An aqueous ammonia solution was prepared by combining 70 kg of deionized water with 14 kg of a 25% aqueous ammonia solution (this resulted in a molar ratio of NH4OH in the aqueous ammonia solution to the total amount of cerium and lanthanum in the cerium nitrate solution being 10). The aqueous ammonia solution was then degassed in a 100 L jacketed reactor by stirring and nitrogen bubbling.

[0107] Next, under nitrogen purging and with the same stirring, the cerium nitrate solution was added to the aqueous ammonia solution at ambient temperature. The temperature of the reaction mixture was then raised to 88°C and maintained at that temperature for 13.5 hours. The reaction mixture was then allowed to cool, and after cooling, the pH was acidified to 2 by adding 68% nitric acid.

[0108] The reaction mixture was then filtered and washed with deionized water. Washing was repeated when the conductivity of the washing solution fell below 0.04 mS / cm. The final cerium oxide concentration was adjusted to 10 mass percent by adding deionized water. The cubic ceria abrasive particles contained 10 mole percent lanthanum oxide and 90 mole percent cerium oxide.

[0109] Nitrogen adsorption increases the BET specific surface area to 8.6 m². 2 The particle size was determined to be per gram. The average particle size was measured using a Malvern Zetasizer and was 142 nm.

[0110] Under the above conditions, a blanket TEOS wafer was polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 6. All removal rates (RR) are given in angstroms per minute (Å / min). [Table 6]

[0111] As is readily apparent from the data shown in Table 6, compositions 7B and 7C exhibited equivalent TEOS removal rates, exceeding 1.6 times the removal rate of composition 7A.

[0112] Example 8 The effect of lanthanum doping levels in cubic ceria abrasive particles on the TEOS removal rate was evaluated by testing three types of abrasive compositions. Compositions 8A and 8B each contained 83.3 ppm by mass of picolinic acid, 1000 ppm by mass of poly(ethylene glycol) (approximately 8000 g / mol MW), 10.7 ppm by mass of Kordek MLX, and 0.4% by mass of ceria abrasive. Composition 8A contained a control ceria (Example 2). Composition 8B contained cubic ceria abrasive particles containing 2.5 mol% lanthanum oxide. Composition 8C contained 58.3 ppm by mass of picolinic acid, 700 ppm by mass of poly(ethylene glycol) (approximately 8000 g / mol MW), 7.5 ppm by mass of Kordek MLX, and 0.28% by mass of cubic ceria abrasive particles containing 10 mol% lanthanum oxide. The pH of each of compositions 8A to 8C was 4.

[0113] Under the above conditions, a blanket TEOS wafer was polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 7. All removal rates (RR) are expressed in angstroms per minute (Å / min). [Table 7]

[0114] As is readily apparent from the results shown in Table 7, the cubic ceria-based compositions (8B and 8C) exhibited similar TEOS removal rates. Furthermore, the cubic ceria compositions showed significantly improved TEOS removal rates compared to the control (an improvement of approximately 60 percent).

[0115] When “a,” “an,” “the,” and similar referents are used in the context of describing the present invention, they should be interpreted as covering both singular and plural forms unless otherwise specified or the context clearly contradicts this. The terms “comprising,” “having,” “including,” and “containing” should be interpreted as open-ended terms (i.e., “including, but not limited to”) unless otherwise specified. Unless otherwise specified, descriptions of ranges of values ​​in this specification are intended merely as abbreviations to refer individually to each distinct value contained within that range, and each distinct value is incorporated herein as if it were described individually. All methods described herein may be carried out in any appropriate order unless otherwise specified herein or the context clearly contradicts this. Any and all examples, or language meaning examples (e.g., “such as”), provided herein are intended merely to better illustrate the present invention. No language in this specification should be construed as indicating that any non-claim element is essential for the implementation of the invention.

[0116] Preferred embodiments of the present invention are described herein, including the best modes known to the inventors for carrying out the invention. Modifications of these preferred embodiments may be apparent to those skilled in the art by reading the foregoing description. The inventors anticipate that those skilled in the art will adopt such modifications as appropriate, and the inventors intend that the invention may be carried out in ways different from those specifically described herein. Accordingly, the invention includes all modifications and equivalents of the subject matter set forth in the claims herein, as permitted by applicable law. Furthermore, any combination of the above elements in any possible modification is encompassed by the invention unless otherwise specifically stated herein or clearly rejected by the context.

[0117] Needless to say, the disclosure includes numerous embodiments beyond those included in the examples above. These embodiments include, but are not limited to, the forms set forth in the appended claims.

Claims

1. A method for chemically and mechanically polishing a substrate containing a silicon dioxide dielectric material, wherein the method is (a) (i) a liquid carrier, (ii) cubic ceria abrasive particles dispersed in the liquid carrier, and (iii) at least one of an anionic compound and a nonionic compound, wherein the anionic compound is selected from poly(acrylic acid), poly(methacrylic acid), poly(vinyl sulfonic acid) and dodecylbenzenesulfonic acid, and the nonionic compound is selected from poly(ethylene glycol), polyvinylpyrrolidone and poly(vinylpyrrolidone-co-vinyl acetate), (b) The substrate is brought into contact with the prepared polishing composition, (c) Move the polishing composition with respect to the substrate, and (d) Grinding the substrate to remove a portion of the silicon oxide dielectric material from the substrate, thereby polishing the substrate. Includes, The abrasive composition contains 0.01 to 2% by mass of cubic ceria abrasive particles at the point of use, the cubic ceria abrasive particles contain a mixture of cerium oxide and lanthanum oxide, and have an average particle size in the range of 50 to 500 nm. The aforementioned anionic compound includes poly(acrylic acid), The pH of the abrasive composition is in the range of 4 to 6, and During grinding in step (d), the removal rate of the silicon dioxide dielectric material is at least 1000 Å / min. method.

2. The substrate further comprises at least one of a silicon nitride material and a polysilicon material, and The removal rate selectivity of the silicon oxide dielectric material to the silicon nitride material, or the removal rate selectivity of the silicon oxide dielectric material to the polysilicon material, is greater than 10:1 in step (d). The method according to claim 1.

3. A method for chemically and mechanically polishing a substrate containing a silicon dioxide dielectric material, wherein the method is (a) (i) a liquid carrier, (ii) cubic ceria abrasive particles dispersed in the liquid carrier, and (iii) at least one of an anionic compound and a nonionic compound, wherein the anionic compound is selected from poly(acrylic acid), poly(methacrylic acid), poly(vinyl sulfonic acid) and dodecylbenzenesulfonic acid, and the nonionic compound is selected from poly(ethylene glycol), polyvinylpyrrolidone and poly(vinylpyrrolidone-co-vinyl acetate), (b) The substrate is brought into contact with the prepared polishing composition, (c) Move the polishing composition with respect to the substrate, and (d) Grinding the substrate to remove a portion of the silicon oxide dielectric material from the substrate, thereby polishing the substrate. Includes, The abrasive composition contains 0.01 to 2% by mass of cubic ceria abrasive particles at the point of use, the cubic ceria abrasive particles contain a mixture of cerium oxide and lanthanum oxide, and have an average particle size in the range of 50 to 500 nm. The nonionic compound includes polyvinylpyrrolidone, The pH of the abrasive composition is in the range of 4 to 6. The substrate further comprises a silicon nitride material, and The removal rate selectivity of the silicon oxide dielectric material to the silicon nitride material is less than 1:1 in step (d). method.

4. A method for chemically and mechanically polishing a substrate containing a silicon dioxide dielectric material, wherein the method is (a) (i) a liquid carrier, (ii) cubic ceria abrasive particles dispersed in the liquid carrier, and (iii) at least one of an anionic compound and a nonionic compound, wherein the anionic compound is selected from poly(acrylic acid), poly(methacrylic acid), poly(vinyl sulfonic acid) and dodecylbenzenesulfonic acid, and the nonionic compound is selected from poly(ethylene glycol), polyvinylpyrrolidone and poly(vinylpyrrolidone-co-vinyl acetate), (b) The substrate is brought into contact with the prepared polishing composition, (c) Move the polishing composition with respect to the substrate, and (d) Grinding the substrate to remove a portion of the silicon oxide dielectric material from the substrate, thereby polishing the substrate. Includes, The abrasive composition contains 0.01 to 2% by mass of cubic ceria abrasive particles at the point of use, the cubic ceria abrasive particles contain a mixture of cerium oxide and lanthanum oxide, and have an average particle size in the range of 50 to 500 nm. The anionic compound includes poly(methacrylic acid), poly(vinyl sulfonic acid), dodecylbenzenesulfonic acid, and mixtures thereof. The pH of the composition is in the range of 9 to 11, and During grinding in step (d), the removal rate of the silicon dioxide dielectric material is at least 2000 Å / min. method.

5. The substrate further comprises a silicon nitride material, The removal rate selectivity of the silicon oxide dielectric material to the silicon nitride material is less than 10:1 in step (d). The method according to claim 4.

6. The method according to any one of claims 1, 3, and 4, wherein preparing the polishing composition comprises (ai) preparing a polishing concentrate, and (aiii) diluting the polishing concentrate with at least one part of water to one part of the polishing concentrate.

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