Self-stop polishing compositions and methods

Abstract

The invention relates to a self-stopping polishing composition and a method. A chemical mechanical polishing composition for polishing a substrate having a silica material, comprising, consisting of, or consisting essentially of: a liquid carrier; cubic ceria abrasive particles dispersed in the liquid carrier; a self-stopping agent; and a cationic polymer.

Description

[0001] This application is a divisional application of a patent application with application number 202080074250.3, filing date October 22, 2020, and invention title "Self-Stopping Polishing Composition and Method".

[0002] Cross-reference to related applications

[0003] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 924,342, filed October 22, 2019, titled Self-Stopping Polishing Composition and Method. Background art

[0004] Chemical mechanical polishing is a key enabling technology in the manufacture of integrated circuits (ICs) and micro-electro-mechanical systems (MEMS). CMP compositions and methods for polishing (or planarizing) the surface of a substrate, such as a wafer, are well known in the art. A polishing composition (also referred to as a polishing slurry, CMP slurry, and CMP composition) typically includes abrasive particles suspended (dispersed) in an aqueous solution and chemical additives for increasing the material removal rate, improving the planarization efficiency, and / or reducing the defect density during a CMP operation.

[0005] In certain polishing applications, it is desirable for a CMP composition to exhibit "self-stopping" behavior such that the removal rate decreases when most of the "high points" (i.e., raised regions) of the surface have been removed. In a self-stopping polishing application, when a significant step height exists at the substrate surface, the removal rate is actually high, and then, when the surface becomes substantially flat, the removal rate decreases. In various dielectric polishing steps (e.g., in a STI process), the removal rate of a patterned dielectric material (e.g., a dielectric layer) is typically the rate-limiting factor for the entire process. Therefore, a high removal rate of the patterned dielectric material is needed to increase throughput. In addition, good efficiency in the form of relatively low trench loss is desired. Further, if the removal rate of the dielectric remains high after planarization is achieved, over-polishing occurs, resulting in additional trench loss.

[0006] The advantages of the self-stopping slurry are generated by a reduced blanket removal rate, which results in a wider endpoint window. For example, the self-stopping behavior allows for the polishing of substrates with a reduced thickness of the dielectric film, thereby allowing a reduced amount of material to be deposited on the structured underlying layer. In addition, motor torque endpoint detection can be used to more effectively monitor the final topography. By avoiding over-polishing or unnecessary dielectric removal after planarization, the substrate can be polished with lower trench loss.

[0007] Ceria (cerium oxide) abrasives are well known in the art, particularly for polishing silicon-containing substrates, such as those comprising silicon oxide materials such as tetraethyl orthosilicate (TEOS), silicon nitride, and / or polysilicon. Ceria abrasive compositions are commonly used in advanced dielectric applications, such as shallow trench isolation applications. Despite the known uses of ceria abrasives, there is a need for improved ceria-based CMP compositions. In particular, there is a need to provide compositions and methods for chemical mechanical polishing of silicon oxide-containing substrates that provide suitable removal rates while also providing improved planarization efficiency. SUMMARY OF THE INVENTION

[0008] Disclosed is a chemical mechanical polishing composition for polishing a substrate having a silicon oxy material (such as silicon oxide). In one embodiment, the polishing composition comprises, consists essentially of, or consists of: a liquid carrier; cubic ceria abrasive particles dispersed in the liquid carrier; a self-stopping agent; and a cationic polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To more fully understand the disclosed subject matter and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0010] Figure 1 AND Figure 2 A transmission electron microscopy (TEM) micrograph depicting a cubic ceria abrasive sample showing ceria abrasive particles having square faces.

[0011] Figure 3 A scanning electron microscopy (SEM) micrograph depicting a cubic ceria abrasive sample showing ceria abrasive particles having square faces.

[0012] Figure 4 A graph depicting the effective loss (in Å) of a patterned wafer polished in Example 6 versus pattern type. DETAILED DESCRIPTION

[0013] A chemical mechanical polishing composition for polishing a substrate having a silicon oxide material, such as silicon oxide, is disclosed. The polishing composition comprises, consists of, or consists essentially of: a liquid carrier; cubic ceria abrasive particles dispersed in the liquid carrier; a self-stopping agent; and a cationic polymer. In one embodiment, the self-stopping agent comprises benzyl hydroxamic acid, salicyl hydroxamic acid, kojic acid, or potassium sorbate. In another embodiment, the cationic polymer comprises poly(vinyl imidazole ), poly(methacryloyloxyethyltrimethylammonium), polylysine or polyquaternium-7.

[0014] The disclosed polishing compositions and corresponding (CMP methods) can impart significant and unexpected advantages. For example, the disclosed compositions can provide significantly improved active oxide removal rates and can therefore increase throughput and save time and money (i.e., via improved planarization times). The disclosed compositions can further provide improved planarization on various patterned oxide structures. The disclosed compositions can further provide improved / reduced trench loss and improved self-stopping behavior (reduced blanket rate).

[0015] The polishing composition contains abrasive particles, which include cubic ceria abrasive particles suspended in a liquid carrier. "Cubic" means that the ceria abrasive particles are in the form or shape of a cube, that is, substantially cubic. In other words, the cubic ceria abrasive particles are cubic in form or nature. However, it should be understood that the side dimensions, corners and corner angles do not have to be exactly or precisely those side dimensions, corners and corner angles of a perfect cube. For example, the cubic abrasive particles may have slightly rounded or cut corners, slightly rounded edges, side dimensions that are not completely equal to each other, corner angles that are not completely 90 degrees and / or other slight irregularities, and still maintain the basic shape of a cube. Those of ordinary skill in the art will be able to easily recognize (e.g., via scanning electron microscopy or transmission electron microscopy) that the cubic ceria abrasive particles are in the form of cubes with tolerances that generally allow particle growth and deaggregation.

[0016] Figure 1 , Figure 2 and Figure 3Depict exemplary cubic ceria abrasive particles. These transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images depict ceria abrasive particles having square faces. For example, in these images, the depicted particle faces each include four sides having substantially the same length (e.g., within 20% of each other, or even within 10% of each other or less). Additionally, each side meets at a corner at an angle of approximately 90 degrees (e.g., within the range of about 80 to 100 degrees or about 85 to about 95 degrees). One of ordinary skill in the art will readily understand that in TEM and SEM images, the vast majority of the depicted abrasive particles are cubic because they have square faces as defined above. Some of the particles can be observed to include defects, for example, at one or more of the corners. Additionally, it should be understood that the term cubic is not intended to describe ceria abrasive particles that are precisely cubic, but rather particles that are generally cubic in nature as depicted in Figure 1 , Figure 2 and Figure 3 as depicted.

[0017] As used herein, a chemical mechanical polishing composition comprising cubic ceria abrasive is a composition in which at least 25 number % of the abrasive particles are generally cubic in nature (in the cubic form or shape as described above). In a preferred embodiment, at least 40 number % (e.g., at least 60% or at least 80%) of the abrasive particles are generally cubic in nature. As noted above, using TEM or SEM images at magnifications in the range of, for example, about 10,000× to about 500,000×, cubic ceria abrasive particles can be readily evaluated and counted. The SEM or TEM images show abrasive particles having faces with four side lengths that are similar (e.g., within 20% of each other as described above). The images also show that adjacent sides are approximately perpendicular, for example, forming an angle of about 90 degrees (e.g., also as described above, within the range of about 80 to about 100 degrees). To determine whether a ceria abrasive composition includes cubic ceria abrasive particles, SEM or TEM observations should be made on a large number of randomly selected particles (i.e., more than 200) such that a statistical analysis is possible and the percentage of particles having square faces can thereby be determined). The particles retained must be such that their images are clearly visible on the micrograph. Some of the particles may exhibit some defects on one or more of their surfaces and / or their corners but are still considered cubic.

[0018] The cubic ceria abrasive grains can be substantially pure ceria abrasive grains (within normal tolerances for impurities) or doped ceria abrasive grains. The doped ceria abrasive grains can include 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 can substantially include any metal atom, such as including Ca, Mg, Zn, Zr, Sc, or Y.

[0019] In certain advantageous embodiments, the dopant can include one or more lanthanide elements, such as including lanthanum, praseodymium, neodymium, promethium, samarium, and the like. In one particularly suitable embodiment, the cubic ceria abrasive grains include a mixed oxide of cerium and lanthanum. The molar ratio of La to (La + Ce) of the mixed oxide abrasive grains can be in the range of about 0.01 to about 0.15, such as about 0.01 to about 0.12. It should be understood that such abrasive grains can additionally include other elements and / or oxides (e.g., as impurities). Such impurities can be sourced from the raw materials or starting materials used in the preparation of the abrasive grains. The total proportion of impurities is preferably less than 0.2 wt% of the grains. Residual nitrates are not considered impurities.

[0020] In certain embodiments, the molar ratio of La to (La + Ce) can be in the range of about 0.01 to about 0.04 (e.g., about 0.02 to about 0.03). In one such embodiment, the cubic ceria abrasive grains include about 2.5 mol% of lanthanum oxide and about 97.5 mol% of cerium oxide. In other embodiments, the molar ratio can be in the range of about 0.08 to about 0.12 (e.g., about 0.09 to about 0.11). In one such other embodiment, the cubic ceria abrasive grains include about 10 mol% of lanthanum oxide and about 90 mol% of cerium oxide. The abrasive grains can 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 symmetric x-ray diffraction pattern with peaks located between about 27 degrees and about 29 degrees, and the peaks are shifted to a lower angle than pure cerium oxide. The solid solution can be obtained when the temperature of the aging sub-step (described below) is higher than about 60 °C. As used herein, the term "solid solution" means that the x-ray diffraction only shows the pattern of the cerium oxide crystal structure, with or without a shift in individual peaks, but no additional peaks indicating the presence of other phases.

[0021] The cubic ceria abrasive particles may optionally also be characterized by their specific surface area, which is measured by adsorbing nitrogen on the powder using the Brunauer-Emmett-Teller method (BET method). This method is disclosed in ASTM D3663-03 (reapproved in 2015). The specific surface area of the abrasive particles can be in the range of about 3 to about 14 m 2 / g (e.g., about 7 to about 13 m 2 / g or about 8 to about 12 m 2 / g).

[0022] The cubic ceria abrasive particles may optionally also be characterized by their average particle size and / or particle size distribution. The average particle size of the abrasive particles can be in the range of 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). Additionally, the average particle size can 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 measured via dynamic light scattering (DLS) and corresponds to the median particle size (D50). DLS measurements can be performed, for example, using a Zetasizer (available from Malvern Instruments). Those of ordinary skill in the art will readily understand that when measurements are made in the presence of relatively large particles, DLS measurements can significantly undercount the number of small particles. For the cubic ceria abrasive particles disclosed herein, the DLS technique tends to undercount particles below about 40 nm. It should be understood that the disclosed embodiments can include a large number of such small particles (less than 40 nm) that are not counted by DLS and thus do not contribute to the average particle size.

[0023] Laser diffraction techniques may optionally also be used to characterize the particle size distribution. Those of ordinary skill in the art will readily understand that laser diffraction techniques also tend to undercount small particles (e.g., less than 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 measurements, various parameters can be obtained, including, for example, D10, D50, D90, D99, and the dispersion index (defined below). Based on the laser diffraction measurements, the abrasive particles can have a median diameter (D50) in the range of about 100 nm to about 700 nm (e.g., about 100 nm to about 200 nm). For example, D50 can be in the range of 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.

[0024] The D10 of the cubic cerium abrasive particles can optionally be in the range of 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). It should be understood that D10 represents the particle size obtained by laser diffraction, where 10% of the particles have a diameter less than D10.

[0025] The D90 of the cubic cerium abrasive particles can optionally be in the range of 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 represents the particle size obtained by laser diffraction, where 90% of the particles have a diameter less than D90. The D90 of the abrasive particles that have been mechanically de-aggregated can be less than about 300 nm.

[0026] The cubic cerium abrasive particles can optionally exhibit a low dispersion index. The "dispersion index" is defined by the following formula: dispersion index = (D90 - D10) / 2·D50. The dispersion index can be less than about 0.60, e.g., (less than about 0.5, less than about 0.4, or less than about 0.30). The dispersion index of the abrasive particles that have been mechanically de-aggregated can be less than about 0.30. In addition, the D90 / D50 of the particles that have been mechanically de-aggregated can be in the range of about 1.3 to about 2.

[0027] The D99 of the cubic cerium abrasive particles can optionally be in the range of 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 abrasive particles that have been mechanically de-aggregated can be less than about 600 nm (e.g., less than about 500 or less than about 400). D99 represents the particle size obtained by laser diffraction, where 99% of the particles have a diameter less than D99.

[0028] The abrasive particles can be prepared using substantially any suitable method for producing cubic ceria abrasive particles. The disclosed embodiments relate to a chemical mechanical polishing composition comprising such abrasive particles and to a method of polishing a substrate using such abrasive particles and are not limited to any particular method for producing the particles. In certain embodiments, cubic ceria abrasive particles can be prepared by precipitating cerium nitrate (and, when preparing doped ceria abrasives, other nitrates that may be present). The precipitated material can then be grown in a specific temperature and pressure regime to promote the growth of cubic ceria abrasive particles. The particles can then be cleaned and deaggregated. A dispersion of the cubic ceria abrasive particles can then be prepared and used to formulate the chemical mechanical composition of the present invention.

[0029] In one advantageous embodiment, cubic cerium lanthanum oxide abrasive particles can be prepared by precipitating nitrates of cerium and lanthanum. One such preparation method comprises the following steps:

[0030] (i) Mixing an aqueous cerium nitrate solution and an aqueous base solution under an inert atmosphere.

[0031] (ii) Heating the mixture obtained in (i) under an inert atmosphere.

[0032] (iii) Optionally acidifying the heat-treated mixture obtained in (ii).

[0033] (iv) Washing the solid material obtained in (ii) or (iii) with water.

[0034] (v) Mechanically treating the solid material obtained in (iv) to deaggregate the ceria particles.

[0035] The cerium nitrate solution used in step (i) of the above method can be prepared by mixing aqueous solutions of cerium nitrate and lanthanum nitrate. The aqueous solution contains Ce III 、Ce IV and La III and can be characterized by a Ce IV to total Ce molar ratio between about 1 / (500,000) and about 1 / (4,000). In one exemplary embodiment, the molar ratio can be between about 1 / (100,000) and about 1 / (90,000). It is generally advantageous to use high purity salts and components, such as having a purity of at least 99.5 weight percent or even 99.9 weight percent.

[0036] Step (i) involves mixing / reacting an aqueous cerium nitrate solution with an aqueous base solution. A hydroxide type base can be advantageous, such as including alkali metal or alkaline earth metal hydroxides and aqueous ammonia. Secondary, tertiary or quaternary amines can also be used. The aqueous solution of the base can also be pre-degassed (deoxygenated) by bubbling an inert gas through it. The mixing can be achieved by introducing the aqueous cerium nitrate solution into the aqueous base solution and is advantageously carried out under an inert atmosphere, such as in a closed reactor or a semi-closed reactor with a purge of an inert gas (e.g., nitrogen or argon). The mixing can also be carried out with stirring. The molar ratio of the base to (Ce + La) can be between about 8.0 and about 30.0 (e.g., greater than about 9.0). Step (i) can further be carried out at a temperature between about 5°C and about 50°C (e.g., between about 20°C and 25°C).

[0037] Step (ii) involves heating the mixture obtained at the end of the foregoing step and can include a heating sub-step and an aging sub-step. The heating sub-step can include heating the mixture to a temperature in the range of about 75°C to about 95°C (e.g., about 85°C to about 90°C). The aging sub-step can include maintaining (holding) the mixture at this temperature for a duration in the range of about 2 hours to about 20 hours. Generally, the aging time decreases as the temperature increases. Step (ii) can also be carried out under an inert atmosphere and with stirring as described for step (i) above.

[0038] In step (iii), the mixture obtained at the end of step (ii) can be acidified, for example, using nitric acid. The heat-treated reaction mixture can be acidified (e.g.) to a pH below about 3.0 (e.g., in the range of about 1.5 to about 2.5).

[0039] In step (iv), the solid material obtained in step (ii) or (iii) can be washed with water (e.g., deionized water). The washing can be used to reduce the residual nitrates in the final dispersion and obtain the target conductivity. The washing can include filtering the solid from the mixture and redispersing the solid in water. If necessary, several filtrations and redispersions can be carried out.

[0040] In step (v), the washed solid material obtained in (iv) can be optionally mechanically treated to deaggregate or partially deaggregate the ceria abrasive particles. The mechanical treatment can include, for example, bi-jet treatment or ultrasonic deaggregation and generally results in a narrow particle size distribution and a reduction in the number of large aggregated particles.

[0041] After step (iv) or (v), the solid material can be dried to obtain cerium-based particles in the form of a powder. The powder can be redispersed by adding water or a mixture of water and a miscible liquid organic compound to obtain a dispersion of the cerium-based particles in a liquid medium. The liquid medium can be water or a mixture of water and a water-miscible organic liquid. The water-miscible organic liquid can 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, ethyl lactate. The ratio of water to the organic liquid can be between 80 to 20 parts by weight and 99 to 1 parts by weight. In addition, the dispersion can include from about 1 weight percent to about 40 weight percent of the cerium-based particles, for example, between about 10 weight percent and about 35 weight percent. The conductivity of the dispersion can also be less than about 300 μS / cm, for example, less than about 150, more specifically below 150 μS / cm or less than about 100 μS / cm.

[0042] The polishing composition can include substantially any suitable amount of cubic ceria abrasive particles. For example, the polishing composition can include at least about 0.001 weight percent (10 ppm) or more of cubic ceria abrasive particles at the point of use (e.g., about 0.002 weight percent or more, about 0.005 weight percent or more, about 0.01 weight percent or more, about 0.02 weight percent or more, about 0.05 weight percent or more, or about 0.1 weight percent or more). The polishing composition can include about 5 weight percent or less of cubic ceria abrasive particles at the point of use (e.g., about 2 weight percent or less, about 1.5 weight percent or less, about 1 weight percent or less, or about 0.5 weight percent or less). It should be understood that the cubic ceria abrasive particles can be present in the polishing composition at a concentration defined by any two of the foregoing endpoints. For example, the concentration of cubic ceria abrasive particles in the polishing composition can be in the range of about 0.001 weight percent to about 5 weight percent at the point of use (e.g., about 0.005 weight percent to about 1 weight percent, about 0.01 weight percent to about 1 weight percent, or about 0.01 weight percent to about 0.5 weight percent).

[0043] An aqueous liquid is used to assist in applying the abrasive and any optional chemical additives to the surface of a substrate to be polished (e.g., planarized). Aqueous means that the liquid carrier is made of at least 50 wt% water (e.g., deionized water). The liquid carrier can include other suitable non-aqueous carriers, such as including lower alcohols (e.g., methanol, ethanol, etc.) and ethers (e.g., di ane, tetrahydrofuran, etc.). Preferably, the liquid carrier consists essentially of water (and more preferably deionized water), or consists of water (and more preferably deionized water).

[0044] Polishing compositions are generally weakly acidic, neutral, or basic, having a pH in the range of about 5 to about 10 (e.g., greater than about 5 and / or less than about 10). In certain embodiments, the polishing composition can be neutral or weakly basic, having a pH in the range of about 6 to about 10 (e.g., about 6.5 to about 9.5, or about 7 to about 9). In such embodiments, the pH of the polishing composition can be about 8 (e.g., about 7.5 to about 8.5). In an alternative embodiment, the polishing composition is weakly acidic or neutral, having a pH in the range of about 5 to about 8 (e.g., about 5 to about 7 or about 5 to about 6.5). In one such embodiment, the pH of the polishing composition is about 5 (e.g., about 5.5 to about 6.5). In one embodiment, the disclosed embodiments provide excellent self-stopping efficacy at weakly acidic pH values.

[0045] The polishing composition includes a self-stopping agent. Exemplary self-stopping agents are disclosed in co-owned U.S. Patent Publication 2019 / 0185716. A self-stopping agent is a compound that promotes a relatively high pattern removal rate and a relatively low blanket removal rate and further promotes the transition from a relatively high pattern removal rate to a relatively low blanket removal rate after planarizing the substrate. For example, the self-stopping agent can be a ligand attached to cubic ceria abrasive particles. In some polishing applications, the concentration of the self-stopping agent affects the observed effect, since at low concentrations, the self-stopping agent can act as a rate enhancer (e.g., a "high" removal rate is observed), and self-stopping behavior is observed at higher concentrations (e.g., a "stopped" removal rate is observed). Thus, some self-stopping agents can have a dual role. For example, when the polishing composition contains a low concentration of picolinic acid, picolinic acid can act as a rate enhancer. However, when the polishing composition contains a high concentration of picolinic acid, picolinic acid can act as a self-stopping agent. For example, picolinic acid can act as a rate enhancer at a concentration below about 1000 weight ppm at the point of use.

[0046] In some embodiments of the present invention, the self-stopping agent has the formula Q-B, where Q is a substituted or unsubstituted hydrophobic group, or a sterically hindering group, and B is a bonding group such as -C(O)-C-OH, -C(O)-C-C-OH, or -C(O)-OH. The bonding group can also be -C(O)-X-OH, where X is a C1-C2 alkyl group. When the self-stopping agent is a compound of the formula Q-B as described herein, Q can be any suitable hydrophobic group or any suitable group that provides steric hindrance. Suitable hydrophobic groups include saturated and unsaturated hydrophobic groups. The hydrophobic group can be straight-chain or branched-chain and can include straight-chain or branched-chain alkyl groups, cycloalkyl groups, and ring structures including aromatic groups, heterocyclic groups, heteroaromatic groups, fused ring systems, and combinations thereof.

[0047] Q can be an alkyl group. Suitable alkyl groups include, for example, straight-chain or branched-chain, saturated or unsaturated, substituted or unsubstituted hydrocarbon groups having 1 to 30 carbon atoms (e.g., C1-C30 alkyl, C1-C24 alkyl, C1-C18 alkyl, C1-C12 alkyl, or even C1-C6 alkyl), such as those having at least 1 carbon atom (i.e., methyl), at least 2 carbon atoms (e.g., ethyl, vinyl), at least 3 carbon atoms (e.g., propyl, isopropyl, propenyl, etc.), at least 4 carbon atoms (butyl, isobutyl, sec-butyl, butane, etc.), at least 5 carbon atoms (pentyl, isopentyl, sec-pentyl, neopentyl, etc.), at least 6 carbon atoms (hexyl, etc.), at least 7 carbon atoms, at least 8 carbon atoms, at least 9 carbon atoms, at least 10 carbon atoms, at least 11 carbon atoms, at least 12 carbon atoms, at least 13 carbon atoms, at least 14 carbon atoms, at least 15 carbon atoms, at least 16 carbon atoms, at least 17 carbon atoms, at least 18 carbon atoms, at least 19 carbon atoms, at least 20 carbon atoms, at least 25 carbon atoms, or at least 30 carbon atoms.

[0048] A substituted group means a group in which one or more hydrogen atoms bonded to carbon are replaced by non-hydrogen atoms. Illustrative substituents include, for example, hydroxyl, keto, ester, amide, halogen (e.g., fluorine, chlorine, bromine, and iodine), amino (primary, secondary, tertiary, and / or quaternary types), and combinations thereof.

[0049] Q can be a cycloalkyl group. Suitable cycloalkyl groups include, for example, saturated or unsaturated, substituted or unsubstituted cycloalkyl groups having 3 to 20 carbon atoms (e.g., C3-C20 cyclic groups). For example, suitable cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and combinations thereof. Additionally, suitable unsaturated cycloalkyl groups include, for example, cyclobutene, cyclopentene, cyclohexene, and combinations thereof.

[0050] Q can be an aromatic group. Suitable aromatic groups include, for example, substituted or unsubstituted aromatic groups having 1 to 20 carbon atoms. For example, suitable aromatic groups include phenyl, benzyl, naphthyl, azulene, anthracene, pyrene, and combinations thereof.

[0051] Q can be a heteroaromatic group. "Heteroatom" is defined herein as any atom other than carbon and hydrogen atoms. Suitable heteroatom-containing functional groups include, for example, hydroxyl, carboxyl, ester, keto, amino (e.g., primary, secondary, and tertiary amino), amido, imino, thioester, thioether, nitrile, nitro, halogen groups, and combinations thereof.

[0052] Suitable heterocyclic groups include, for example, cycloaliphatic compounds containing from 1 to 20 carbon atoms and containing nitrogen, oxygen, sulfur, phosphorus, boron, and combinations thereof. The heterocyclic compounds can be saturated and unsaturated, substituted or unsubstituted. Heterocyclic compounds refer to 5-membered, 6-membered, or 7-membered ring compounds having one or more heteroatoms (such as N, O, S, P, or B) as part of the ring system. Illustrative heterocyclic compounds include, for example, triazole, aminotriazole, 3-amino-1,2,4-triazole, 3-amino-1,2,4-triazole-5-carboxylic acid, 3-amino-5-mercapto-1,2,4-triazole, 4-amino-5-hydrazino-1,2,4-triazole-3-thiol, thiazole, 2-amino-5-methylthiazole, 2-amino-4-thiazoleacetic acid, heterocyclic N-oxides, 2-hydroxypyridine-N-oxide, 4-methylmorpholine-N-oxide, and pyridinecarboxylic acid N-oxide, and the like. Other illustrative heterocyclic compounds include, for example, pyrone compounds, pyridine compounds (including positional isomers and stereoisomers), pyrrolidine, δ-2-pyrroline, imidazolidine, δ-2-imidazoline, δ-3-pyrazoline, pyrazolidine, piperidine, piperazine, morpholine, quinuclidine, indoline, isoindoline, chroman, isochromann, and combinations thereof.

[0053] Suitable heteroaromatic groups include, for example, pyridine, thiophene, furan, pyrrole, 2H-pyrrole, imidazole, pyrazole, iso azole, furazan, isothiazole, pyran (2H), pyrazine, pyrimidine, pyridazine, isobenzofuran, indolizine, indole, 3H-indole, 1H-indazole, purine, isoindole, 4aH-carbazole, carbazole, β-carboline, 2H-chromene, 4H-quinolizine, isoquinoline, quinoline, quinoxaline, 1,8-naphthyridine, phthalazine, quinazoline, cinnoline, pteridine, xanthene, phen oxathiin, phenothiazine, phenazine, perimidine, 1,7-phenanthroline, phenanthridine, acridine, and combinations thereof.

[0054] In some embodiments, Q is substituted with one or more substituents. Suitable substituents can include, for example, any suitable compounds / groups described herein. For example, suitable substituents include alkyl, cycloalkyl, aryl, heterocyclic, heteroaromatic, and combinations thereof.

[0055] In some embodiments, Q is unsubstituted. In other embodiments, Q is a sterically hindering group. For example, Q may not particularly have hydrophobicity, but may be a bulky component that prevents chemical reactions or interactions that would otherwise occur in related molecules with smaller Q groups. Without limitation, examples of self-stopping agents having such Q groups would be maltol, ethyl maltol, and kojic acid.

[0056] In some embodiments, the bonding group B is selected from a carboxyl group, an isohydroxamic acid group, a hydroxylamine group, a hydroxyl group, a keto group, a sulfate group, a phosphate group, and combinations thereof.

[0057] In some embodiments, the self-stopping agent Q-B is selected from kojic acid, maltol, ethyl maltol, propyl maltol, isohydroxamic acid, phenylisohydroxamic acid (benzisohydroxamic acid), tiglic acid, angelic acid, salicylhydroxamic acid, benzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, sorbic acid, potassium sorbate, and combinations thereof. It should be understood that salts of the self-stopping agent of formula Q-B are also suitable for use in the polishing compositions of the present invention.

[0058] The polishing composition may comprise any suitable amount of the self-stopping agent (e.g., a compound of formula Q-B). If the composition includes too little of the self-stopping agent, the composition may not exhibit suitable self-stopping behavior. In contrast, if the polishing composition contains too much of the self-stopping agent, the composition may exhibit undesirable polishing performance (e.g., low removal rate), may not be cost-effective, and / or may lack stability. An advantageous property of the compositions of the present invention is that the use of a stopper in combination with cubic ceria abrasive particles enables the use of a higher concentration of the self-stopping agent. Such compositions of the present invention can advantageously provide excellent active removal rate, excellent self-stopping behavior, and excellent planarization.

[0059] For example, the polishing composition may include at the point of use about 10 weight ppm (0.001 weight percent) or more of a self-stopping agent (e.g., about 20 weight ppm or more, about 50 weight ppm or more, about 100 weight ppm or more, about 200 weight ppm or more, about 250 weight ppm or more or even about 500 weight ppm or more). Thus, the polishing composition may contain from about 10 weight ppm to about 2 weight percent of a self-stopping agent at the point of use. For example, the polishing composition may include from about 20 weight ppm to about 1 weight percent (10,000 ppm) of a self-stopping agent at the point of use (e.g., from about 50 weight ppm to about 10,000 weight ppm, from about 100 weight ppm to about 10,000 weight ppm, from about 200 weight ppm to about 5000 weight ppm or from about 250 weight ppm to about 2500 weight ppm). In certain advantageous embodiments, the polishing composition includes from about 500 weight ppm to about 2000 weight ppm of a self-stopping agent at the point of use.

[0060] The polishing composition may further comprise a cationic polymer (e.g., also referred to as a planarizing agent or a topography control agent). The cationic polymer may include substantially any suitable cationic polymer and may be selected from cationic homopolymers and / or cationic copolymers (which include at least one cationic monomer and at least one non-ionic monomer).

[0061] The cationic polymer may be any suitable cationic homopolymer, including cationic monomer repeat units, for example including quaternary amine groups as repeat units. The quaternized amine group may be acyclic or incorporated into a ring structure. The quaternized amine group includes a tetra-substituted nitrogen atom substituted by four groups independently selected from: alkyl, alkenyl, aryl or aralkyl. When incorporated into a ring structure, the quaternized amine group includes a heterocyclic saturated ring (which contains a nitrogen atom and is further substituted by two groups as described above) or a heteroaryl (e.g., imidazole or pyridine) having another group as described above bonded to the nitrogen atom. The quaternized amine group has a positive charge (i.e., is a cation with an associated anionic moiety, thereby forming a salt). The cationic polymer is also suitable for further modification by alkylation, acylation, ethoxylation or other chemical reactions in order to change the solubility, viscosity or other physical parameters of the cationic polymer. Suitable quaternary amine monomers include, for example, quaternized vinylimidazole (vinylimidazole ) Poly(vinylimidazole), methacryloyloxyethyltrimethylammonium (MADQUAT), diallyldimethylammonium (DADMA), methacryloylaminopropyltrimethylammonium (MAPTA), quaternized dimethylaminoethyl methacrylate (DMAEMA), and combinations thereof. It is understood that MADQUAT, DADMA, MAPTA, and DMAEMA generally include counter anions such as carboxylate (e.g., acetate) or halide anions (e.g., chloride). The disclosed embodiments are not limited in this regard.

[0062] The cationic polymer can also be a copolymer comprising at least one cationic monomer (e.g., as described in the preceding paragraph) and at least one nonionic monomer. Non-limiting examples of suitable nonionic monomers include vinylpyrrolidone, vinylcaprolactam, vinylimidazole, acrylamide, vinyl alcohol, polyvinyl formal, polyvinyl butyral, poly(vinyl phenyl ketone), vinylpyridine, polyacrolein, ethylene, propylene, styrene, epichlorohydrin, and combinations thereof.

[0063] Exemplary cationic polymers include, for example, poly(vinylimidazole); poly(vinylimidazole ); poly(methacryloyloxyethyltrimethylammonium) (polyMADQUAT); poly(diallyldimethylammonium) (e.g., polyDADMAC); poly(diallyldimethylammonium-co-acrylamide); poly(dimethylamine-co-epichlorohydrin); poly[bis(2-chloroethyl) ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (i.e., polyquaternium-2); copolymer of vinylpyrrolidone and quaternized dimethylaminoethyl methacrylate (i.e., polyquaternium-11); copolymer of vinylpyrrolidone and quaternized vinylimidazole (i.e., polyquaternium-16); terpolymer of vinylcaprolactam, vinylpyrrolidone, and quaternized vinylimidazole (i.e., polyquaternium-46); and 3-methyl-1-vinylimidazole methyl sulfate-N-vinylpyrrolidone copolymer (i.e., polyquaternium-44). Additionally, suitable cationic polymers include cationic polymers for personal care, such as Luviquat® Supreme, Luviquat® Hold, Luviquat® UltraCare, Luviquat® FC 370, Luviquat® FC 550, Luviquat® FC 552, Luviquat® Excellence, and combinations thereof.

[0064] In certain advantageous embodiments, the cationic polymer may include poly(methacryloyloxyethyl trimethylammonium), such as polyMADQUAT (e.g., Alco 4773); poly(vinylimidazole) ), such as poly(vinylimidazole) ) methyl sulfate; and imidazole compounds, such as Luviquat® Ultracare.

[0065] In certain embodiments, the cationic polymer may additionally or alternatively include amino acid monomers (such compounds may also be referred to as polyamino acid compounds). Suitable polyamino acid compounds may include substantially any suitable amino acid monomer groups, such as including polyarginine, polyhistidine, polyalanine, polyglycine, polytyrosine, polyproline, and polylysine. In certain embodiments, polylysine may be a preferred cationic polymer. It should be understood that polylysine may include ε-polylysine and / or α-polylysine composed of D-lysine and / or L-lysine. Polylysine may thus include α-poly-L-lysine, α-poly-D-lysine, ε-poly-L-lysine, ε-poly-D-lysine, and mixtures thereof. In certain embodiments, polylysine may be ε-poly-L-lysine. It should be further understood that one or more polyamino acid compounds may be used in any available form, e.g., conjugate acid or conjugate base forms and salt forms may be used instead of (or in addition to) polyamino acids.

[0066] The cationic polymer may also (or alternatively) include derived polyamino acids (i.e., cationic polymers containing derived amino acid monomer units). For example, derived polyamino acids may include derived polyarginine, derived polyornithine, derived polyhistidine, and derived polylysine. CMP compositions including derived polyamino acid compounds are disclosed in U.S. Provisional Patent Application Serial No. 62 / 958,033, which is incorporated herein by reference in its entirety.

[0067] In such embodiments, the derived amino acid monomer includes a derived group bonded to the α-amino of the derived amino acid monomer. The derived group may include substantially any suitable group, such as including alkylcarbonyl, divalent carbonyl (carboacyl), alkylureido, alkylsulfonate groups, alkylsulfonyl, and alkyl ester groups.

[0068] Exemplary alkyl carbonyls include acetyl, pivaloyl, ethyl carbonyl, and the like. Exemplary divalent carbonyls include succinyl, octenyl succinyl, glutaric, methyl succinyl, and the like. Among the divalent carbonyls, succinyl and glutaric may be preferred due to solubility. Exemplary alkylureas include ethyl urea, butyl urea, cyclohexyl urea, and the like. Exemplary alkyl sulfonate groups include methyl sulfonate, dimethyl sulfonate, ethyl sulfonate, propyl sulfonate, butyl sulfonate, penta sulfonate, and the like. Exemplary alkyl sulfone groups include methyl sulfone, ethyl sulfone, propyl sulfone, butyl sulfone, penta sulfone, and the like. Exemplary alkyl ester groups include methyl ester, ethyl ester, propyl ester, butyl ester, pentyl ester, and the like.

[0069] If present, the cationic polymer can be present in the polishing composition at any suitable concentration. An advantageous property of the compositions of the present invention is that the use of a cationic polymer in combination with cubic ceria abrasive particles allows for a higher concentration of the cationic polymer. Such compositions of the present invention can advantageously provide excellent active removal rates, excellent self-stopping behavior, and particularly excellent planarization.

[0070] It has been found that the cationic polymer concentration depends to a large extent on the particular cationic polymer selected and can also depend on the cubic ceria abrasive concentration and the self-stopping agent concentration. Generally, the concentration of the cationic polymer at the point of use is in the range of about 1 weight ppm to about 1000 weight ppm (e.g., about 5 weight ppm to about 500 weight ppm). For example, when the cationic polymer is a poly(vinylimidazole) ) compound, such as poly(vinylimidazole) ) methyl sulfate, the composition can include from about 1 weight ppm to about 75 weight ppm at the point of use. For example, the concentration of the cationic polymer can be in the range of about 5 weight ppm to about 75 weight ppm (e.g., about 5 weight ppm to about 50 weight ppm, about 5 weight ppm to about 40 weight ppm, or about 10 weight ppm to about 40 weight ppm).

[0071] In another example, when the cationic polymer includes poly(methacryloyloxyethyl trimethylammonium) halide (such as polyMADQUAT) or imidazole When the compound is, for example, Luviquat® Ultracare, the composition may include from about 25 ppm by weight to about 1000 ppm by weight at the point of use. For example, the concentration of the cationic polymer may range from about 75 ppm by weight to about 500 ppm by weight (e.g., from about 100 ppm by weight to about 500 ppm by weight, from about 150 ppm by weight to about 500 ppm by weight, or from about 200 ppm by weight to about 400 ppm by weight).

[0072] In another example, when the cationic polymer comprises a polyamino acid compound, such as ε-poly-L-lysine, the composition may include from about 5 ppm by weight to about 500 ppm by weight at the point of use. For example, the concentration of the cationic polymer may range from about 5 ppm by weight to about 400 ppm by weight (e.g., from about 10 ppm by weight to about 300 ppm by weight, from about 15 ppm by weight to about 200 ppm by weight, or from about 20 ppm by weight to about 200 ppm by weight).

[0073] The polishing composition may further include a non-polymeric cationic compound (in addition to the cationic polymer). Suitable cationic compounds include 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 3-(dimethylamino)propyl methacrylamide, 3-(dimethylamino)propyl acrylamide, lysine, 3-methacrylamidopropyl-trimethyl-ammonium, 3-acrylamidopropyl-trimethyl-ammonium, diallyldimethylammonium, 2-(acryloyloxy)-N,N,N-trimethylethanaminium, methacryloyloxyethyl trimethylammonium, N,N-dimethylaminoethyl acrylate benzyl, N,N-dimethylaminoethyl methacrylate benzyl, and combinations thereof.

[0074] It should be understood that 3-methacrylamidopropyl-trimethyl-ammonium, 3-acrylamidopropyl-trimethyl-ammonium, diallyldimethylammonium, 2-(acryloyloxy)-N,N,N-trimethylethanaminium, methacryloyloxyethyl trimethylammonium, N,N-dimethylaminoethyl acrylate benzyl, and N,N-dimethylaminoethyl methacrylate benzyl generally have counter anions, such as carboxylate or halide anions. For example, diallyldimethylammonium is typically provided as diallyldimethylammonium chloride (DADMAC). Unless the counter anion is explicitly recited, the disclosed embodiments are not limited in terms of using any particular counter anion.

[0075] In certain embodiments, the non-polymeric compound preferably includes lysine, methacryloyloxyethyl trimethylammonium, 2-(dimethylamino)ethyl methacrylate, diallyldimethylammonium, and mixtures thereof. In one exemplary embodiment disclosed below, the polishing composition advantageously includes diallyldimethylammonium and optimally includes DADMAC.

[0076] When used, the polishing composition can include substantially any suitable amount of the non-polymeric cationic compound (e.g., depending on the particular compound used and the other components in the composition and the amounts of those components). In certain embodiments, the amount of the non-polymeric cationic compound at the point of use can range from about 1 weight ppm to about 1000 weight ppm (e.g., about 2 weight ppm to about 500 weight ppm, about 5 weight ppm to about 200 weight ppm, or about 10 weight ppm to about 100 weight ppm).

[0077] The polishing composition can further include a polishing rate control agent. The polishing rate control agent can be a polishing rate enhancer (e.g., enhancing the polishing rate on an oxide pattern) or a polishing rate inhibitor (e.g., inhibiting the polishing rate on a trench oxide). The polishing rate enhancer can include, for example, a carboxylic acid compound that activates the polishing particles or the substrate. Suitable rate enhancers include, for example, picolinic acid, nicotinic acid, quinaldic acid, isonicotinic acid, acetic acid, and 4-hydroxybenzoic acid. As noted above, depending on the concentration, picolinic acid can act as a rate enhancer or an inhibitor and can be advantageous in certain embodiments (e.g., as disclosed in the following examples).

[0078] The polishing composition can include substantially any suitable amount of the rate control agent. In one embodiment, the polishing composition includes from about 10 weight ppm (0.001 weight percent) to about 1 weight percent of the rate control agent at the point of use (e.g., about 50 weight ppm to about 0.5 weight percent, about 100 weight ppm to about 0.25 weight percent, or about 200 weight ppm to about 1000 weight ppm).

[0079] The polishing composition can further include a removal rate inhibitor (such as a silicon nitride inhibitor), for example including an unsaturated carboxylic acid, such as an unsaturated monocarboxylic acid. Suitable unsaturated monocarboxylic acids can include, for example, acrylic acid, 2-butenoic acid (crotonic acid), 2-pentenoic acid, trans-2-hexenoic acid, trans-3-hexenoic acid, 2-hexynoic acid, 2,4-hexadienoic acid, potassium sorbate, trans-2-methyl-2-butenoic acid, 3,3-dimethylacrylic acid, or combinations thereof, including their stereoisomers. In one exemplary embodiment disclosed below, the removal rate inhibitor is crotonic acid.

[0080] When in use, the polishing composition can include substantially any suitable amount of removal rate inhibitor (e.g., depending on the particular compound used and other components in the composition and the amounts of those components). In certain embodiments, the amount of removal rate inhibitor at the point of use can be in the range of from about 10 weight ppm to about 1 weight percent (10,000 weight ppm) (e.g., from about 20 weight ppm to about 5,000 weight ppm, from about 50 weight ppm to about 2,000 weight ppm, or from about 100 weight ppm to about 1,000 weight ppm).

[0081] The polishing composition can further include one or both of a pH regulator and / or a pH buffer. The pH regulator can be substantially any suitable pH regulator, such as an alkylamine, an alkanolamine, a quaternary ammonium hydroxide, aqueous ammonia, or combinations thereof. In certain embodiments, suitable pH regulators can include triethanolamine (TEA), tetramethylammonium hydroxide (TMAH or TMA-OH), or tetraethylammonium hydroxide (TEAH or TEA-OH). In one advantageous embodiment, the pH regulator is triethanolamine. The polishing composition can include a sufficient concentration of the pH regulator to obtain and / or maintain the pH of the polishing composition within the pH range set forth above. In one embodiment, the polishing composition includes from about 100 weight ppm to about 1 weight percent of the pH regulator (e.g., triethanolamine) at the point of use.

[0082] The polishing composition can include substantially any suitable buffer, such as phosphates, sulfates, acetates, malonates, oxalates, borates, ammonium salts, azoles, and the like. In certain advantageous embodiments, the pH buffer can include benzotriazole or bis tris methane. The polishing composition can include a sufficient concentration of the pH buffer to provide the desired buffering capacity at a pH within the pH range set forth above. In certain embodiments, the polishing composition can include from about 50 weight ppm to about 0.5 weight percent of the pH buffer (e.g., benzotriazole or bis tris methane) at the point of use.

[0083] The polishing composition can further include other optional additives, such as including secondary polishing rate promoters or inhibitors, dispersants, modifiers, scale inhibitors, chelating agents, stabilizers, and biocides. Such additives are only optional. The disclosed embodiments are not limited thereto and do not require the use of any one or more of such additives.

[0084] The polishing composition may optionally further include a biocide. The biocide may include substantially any suitable biocide, such as isothiazolinone biocides, such as methylisothiazolinone or benzisothiazolone. The amount of biocide in the polishing composition is typically in the range of about 1 weight ppm to about 100 weight ppm at the point of use, such as about 5 weight ppm to about 75 weight ppm.

[0085] The polishing composition can be prepared using any suitable technique, many of which are known to those skilled in the art. The polishing composition can be prepared in a batch or continuous process. Generally, the polishing composition can be prepared by combining its components in any order. As used herein, the term "component" includes individual ingredients (e.g., abrasive particles, self-stopper, cationic polymer, and any optional additives). For example, the self-stopper and cationic polymer can be added to an aqueous carrier (e.g., water) at the desired concentration. The pH can then be adjusted (as needed) and cubic ceria abrasive can be added at the desired concentration to form the polishing composition. The polishing composition can be prepared prior to use, where one or more components are added to the polishing composition just prior to use (e.g., within about 1 minute before use, or within about 1 hour before use, or within about 1 day or about 7 days before use). The polishing composition can also be prepared by mixing the components on the surface of the substrate (e.g., on the polishing pad) during the polishing operation.

[0086] In certain embodiments, the polishing composition can be provided in the form of a "two-package" system. For example, the first package can include cubic ceria abrasive particles, rate control additives, and other optional components and the second package can include a self-stopper, cationic polymer, and other optional components. The first and second packages can be shipped separately and combined on the polishing pad before polishing (e.g., within one hour or one day of polishing) or during the CMP operation.

[0087] The polishing composition of the present invention may be provided in the form of a concentrate intended to be diluted with an appropriate amount of water before use. In such embodiments, the polishing composition concentrate may include cubic ceria abrasive particles and the other components described above, in amounts such that when the concentrate is diluted with an appropriate amount of water, each component of the polishing composition will be present in the polishing composition in amounts within the appropriate ranges recited above for each component. For example, the cubic ceria abrasive particles, the self-stopper, the cationic polymer, and the other optional additives may each be present in the polishing composition in an amount about 3 times (e.g., about 4 times, about 5 times, about 6 times, about 7 times, about 8 times, about 10 times, about 15 times, about 20 times, or about 25 times) the use-point concentration recited above for each component, such that when the concentrate is diluted with an equal volume of (e.g., 2 parts equal volume of water, 3 parts equal volume of water, 4 parts equal volume of water, 5 parts equal volume of water, 5 parts equal volume of water, 6 parts equal volume of water, 7 parts equal volume of water, 9 parts equal volume of water, 14 parts equal volume of water, 19 parts equal volume of water, or 24 parts equal volume of water) water, each component will be present in the polishing composition in amounts within the ranges set forth above for each component.

[0088] In embodiments where the polishing composition is provided in a two-package system, either or both of the packages may be provided in concentrate form and need to be diluted before mixing with the other package. For example, in one embodiment, the first package is provided in concentrate form such that it includes cubic ceria abrasive particles at a concentration about 3 times (e.g., about 5 times, about 8 times, about 10 times, about 15 times, or about 20 times) the use-point concentration described above. The concentrated first package may be mixed with an appropriate amount of water before combining with the second package. Similarly, the second package may be provided in concentrate form such that it includes a self-stopper and a cationic polymer at a concentration about 3 times (e.g., about 5 times, about 8 times, about 10 times, about 15 times, or about 20 times) the use-point concentration described above. In such embodiments, the concentrated second package may be mixed with an appropriate amount of water before combining with the first package. In certain embodiments, both the first and second packages may be diluted with water before combination. The disclosed embodiments are not limited in these respects.

[0089] The polishing method of the present invention is particularly suitable for use in conjunction with a chemical mechanical polishing (CMP) apparatus, such as including a platen and a pad fixed thereto. As is known to those of ordinary skill in the art, polishing of a substrate occurs when the substrate is brought into contact with the polishing pad and the polishing composition of the present invention, and then the polishing pad and the substrate are moved relative to each other to abrade at least a portion of the substrate. The method of the present invention includes providing the composition of the present invention described above, bringing the substrate (e.g., a wafer) into contact with the composition of the present invention, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the silicon oxide material from the substrate and thereby polish the substrate.

[0090] Substrates typically include patterned dielectric layers, many of which are well-known, including various forms of silicon oxides and silicon-oxide-based dielectric materials. For example, a dielectric material including a silicon oxide or a silicon-oxide-based dielectric layer may comprise any one or more of, consist of any one or more of, or consist essentially of any one or more of: tetraethyl orthosilicate (TEOS), high density plasma (HDP) oxide, phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), high aspect ratio process (HARP) oxide, spin-on dielectric (SOD) oxide, chemical vapor deposition (CVD) oxide, plasma enhanced tetraethyl orthosilicate (PETEOS), thermal oxide, or undoped silicate glass.

[0091] The method of the present invention desirably planarizes the patterned dielectric, e.g., by reducing the initial step height between a raised region (having an initial height) and a trench (having an initial trench thickness). To effectively and efficiently achieve this planarization, the method of the present invention desirably has a high removal rate of the raised region (of the active patterned dielectric material) and a significantly lower removal rate of the dielectric material of the trench. Optimally, the method of the present invention also exhibits a self-stopping behavior.

[0092] During the method of the present invention, the dielectric material is removed from the raised region (and may be removed from the trench in a lesser amount). The planarization reduces the height of the raised region such that it is substantially "flush" with the height of the trench. Thus, for example, the step height may be reduced to less than 1,000 angstroms (Å) (e.g., to less than 800 Å, less than 500 Å, less than 300 Å, or less than 250 Å). When a reduced step height (i.e., "remaining" step height) of less than about 1,000 Å (by polishing) is achieved, the surface is considered effectively planarized.

[0093] Depending on the substrate being polished, the initial step height measured before beginning the CMP processing step may be at least 1,000 Å, e.g., at least 2,000 Å, or at least 5,000 Å, and may be substantially greater, such as at least 10,000 Å, at least 20,000 Å, at least 30,000 Å, or at least 40,000 Å.

[0094] During CMP operation, the removal rate of the patterned dielectric is referred to in the art as the "pattern removal rate" or "effective removal rate". The effective removal rate achieved using the methods and polishing compositions described herein can be any suitable rate and, for any given process and substrate, will depend largely on the parameters of the polishing tool selected and the dimensions of the patterned dielectric (e.g., pitch and width). In certain advantageous embodiments, the effective removal rate is greater than about 4,000 Å / min (e.g., greater than about 5,000 Å / min, greater than about 6,000 Å / min, or even greater than about 10,000 Å / min).

[0095] The CMP operation of the present invention also desirably reduces trench loss. For example, the method of the present invention can provide a trench loss of less than about 2,000 Å (e.g., less than about 1,500 Å, less than about 1,000 Å, less than about 500 Å, or less than about 250 Å).

[0096] Lower trench loss can be reflected in improved planarization efficiency. As used herein, planarization efficiency is defined as the step height reduction divided by the trench loss. The method of the present invention can provide a planarization efficiency of at least 4 and preferably greater than 5 or 10 (or greater than 20, or even greater than 50).

[0097] The method of the present invention can also exhibit a self-stop state. Self-stop means that the removal rate of the blanket dielectric material is significantly lower than the removal rate of the patterned dielectric material. Self-stop behavior is considered to occur if the removal rate of the blanket dielectric material is less than about 1,000 Å / min. The method of the present invention can thus exhibit a blanket dielectric removal rate of less than 1000 Å / min (e.g., less than about 500 Å / min).

[0098] By another measurement, the self-stop state can be measured by calculating the ratio of the effective removal rate of the patterned dielectric material to the removal rate of the blanket dielectric material. A high ratio indicates good self-stop behavior. Thus, the method of the present invention can provide a ratio greater than about 5 (e.g., greater than about 10, greater than about 20, or greater than about 50).

[0099] It should be understood that the present invention includes multiple embodiments. These embodiments include (but are not limited to) the following embodiments.

[0100] In a first embodiment, the chemical mechanical polishing composition comprises: a liquid carrier; cubic ceria abrasive particles dispersed in the liquid carrier; a self-stop agent; and a cationic polymer.

[0101] A second embodiment may include the first embodiment, wherein the cubic ceria abrasive particles comprise a mixture of cerium oxide and lanthanum oxide.

[0102] The third embodiment may include any one of the first to second embodiments, wherein the molar ratio of lanthanum to lanthanum + cerium in the cubic cerium oxide abrasive particles ranges from about 1% to about 15%.

[0103] The fourth embodiment may include any one of the first to third embodiments, wherein the BET surface area of the cubic cerium oxide abrasive particles is from about 3 m 2 / g to about 14 m 2 / g.

[0104] The fifth embodiment may include any one of the first to fourth embodiments, wherein the average particle size of the cubic cerium oxide abrasive particles ranges from about 50 to about 500 nm.

[0105] The sixth embodiment may include any one of the first to fifth embodiments, which contains from about 0.01 weight percent to about 1 weight percent of cubic cerium oxide abrasive particles.

[0106] The seventh embodiment may include any one of the first to sixth embodiments, wherein the self-stopping agent is a ligand attached to the cubic cerium oxide abrasive particles.

[0107] The eighth embodiment may include any one of the first to seventh embodiments, wherein the self-stopping agent has the formula Q-B, where Q is a substituted or unsubstituted hydrophobic group, or a steric-hindrance-imparting group, and B is a bonding group attached to the cubic cerium oxide abrasive particles. In such embodiments, the self-stopping agent may include, for example, kojic acid, maltol, ethyl maltol, propyl maltol, hydroxamic acid, phenylhydroxamic acid, salicylhydroxamic acid, benzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, sorbic acid, potassium sorbate, and combinations thereof.

[0108] The ninth embodiment may include any one of the first to eighth embodiments, wherein the self-stopping agent is phenylhydroxamic acid, salicylhydroxamic acid, kojic acid, potassium sorbate, or a combination thereof.

[0109] The tenth embodiment may include any one of the first to ninth embodiments, wherein the cationic polymer is selected from: poly(vinylimidazole ), poly(vinylimidazole),), poly(vinylimidazole), methacryloyloxyethyltrimethylammonium, poly(diallyldimethylammonium), polyquaternium-2, polyquaternium-11, polyquaternium-16, polyquaternium-46, polyquaternium-44, polylysine, and combinations thereof.

[0110] The eleventh embodiment may include any one of the first to tenth embodiments, wherein the cationic polymer is poly(vinylimidazole )), poly(vinylimidazole), methacryloyloxyethyltrimethylammonium, polylysine, or a combination thereof.

[0111] The twelfth embodiment may include any one of the first to eleventh embodiments, wherein (i) the use point concentration of the cubic ceria abrasive particles is from about 0.01 wt% to about 1 wt%, (ii) the use point concentration of the self-stopping agent is from about 200 wt ppm to about 5000 wt ppm; and (iii) the use point concentration of the cationic polymer is from about 5 wt ppm to about 500 wt ppm.

[0112] The thirteenth embodiment may include any one of the first to twelfth embodiments, which further comprises a carboxylic acid rate enhancer.

[0113] The fourteenth embodiment may include any one of the first to thirteenth embodiments, wherein the carboxylic acid rate enhancer is picolinic acid, acetic acid, 4-hydroxybenzoic acid, or a mixture thereof.

[0114] The fifteenth embodiment may include any one of the first to fourteenth embodiments, which further comprises an unsaturated carboxyl-type monocarboxylic acid rate inhibitor selected from: acrylic acid, crotonic acid, 2-pentenoic acid, trans-2-hexenoic acid, trans-3-hexenoic acid, 2-hexynoic acid, 2,4-hexadienoic acid, potassium sorbate, trans-2-methyl-2-butenoic acid, 3,3-dimethylacrylic acid, and combinations thereof.

[0115] The sixteenth embodiment may include any one of the first to fifteenth embodiments, wherein the unsaturated carboxyl-type monocarboxylic acid rate inhibitor is crotonic acid.

[0116] The seventeenth embodiment may include any one of the first to sixteenth embodiments, which further comprises a non-polymeric cationic compound selected from: 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 3-(dimethylamino)propyl methacrylamide, 3-(dimethylamino)propyl acrylamide, lysine, 3-methacrylamidopropyl-trimethyl-ammonium, 3-acrylamidopropyl-trimethyl-ammonium, diallyldimethylammonium, 2-(acryloyloxy)-N,N,N-trimethylethylammonium, methacryloyloxyethyltrimethylammonium, N,N-dimethylaminoethyl phenyl acrylate, N,N-dimethylaminoethyl phenyl methacrylate, and combinations thereof.

[0117] The eighteenth embodiment may include any one of the first to seventeenth embodiments, wherein the non-polymeric cationic compound comprises diallyldimethylammonium, methacryloyloxyethyltrimethylammonium, lysine, 2-(dimethylamino)ethyl methacrylate, or a mixture thereof.

[0118] The nineteenth embodiment may include any one of the first to eighteenth embodiments, wherein the cationic polymer comprises polylysine and the non-polymeric compound comprises diallyldimethylammonium.

[0119] The twentieth embodiment may include any one of the first to nineteenth embodiments, and further comprises a pH regulator, which comprises an alkylamine, an alkanolamine, a quaternary ammonium hydroxide, ammonia water, or a combination thereof. The pH regulator may include, for example, triethanolamine.

[0120] The twenty-first embodiment may include any one of the first to twentieth embodiments, and further comprises benzotriazole or bitrimethane.

[0121] The twenty-second embodiment may include any one of the first to twenty-first embodiments, and has a pH in the range of about 5 to about 10.

[0122] The twenty-third embodiment may include any one of the first to twenty-second embodiments, wherein (i) the self-stopper is benzohydroxamic acid, salicylhydroxamic acid, kojic acid, potassium sorbate, or a combination thereof; (ii) the cationic polymer is poly(vinylimidazole ), poly(methacryloyloxyethyltrimethylammonium), polylysine, poly(diallyldimethylammonium), or a combination thereof; and (iii) the composition further comprises picolinic acid, acetic acid, 4-hydroxybenzoic acid, or a mixture thereof.

[0123] The twenty-fourth embodiment may include the twenty-third embodiment, and further comprises triethanolamine and benzotriazole.

[0124] The twenty-fifth embodiment may include the twenty-third or twenty-fourth embodiment, wherein the self-stopper is benzohydroxamic acid, salicylhydroxamic acid, or a combination thereof and the pH at the point of use is in the range of about 7 to about 9.

[0125] The twenty-sixth embodiment may include any one of the twenty-third to twenty-fifth embodiments, which comprises at least 250 weight ppm of the self-stopper at the point of use and 50 weight ppm of the cationic polymer at the point of use.

[0126] The twenty-seventh embodiment may include the twenty-third embodiment, wherein the self-stopper is kojic acid, potassium sorbate, or a combination thereof and the pH at the point of use is in the range of about 5 to about 6.5.

[0127] The twenty-eighth embodiment may include any one of the first to twenty-second embodiments, wherein (i) the self-stopper is benzohydroxamic acid, salicylhydroxamic acid, or a combination thereof and (ii) the cationic polymer is ε-poly-L-lysine, poly(vinylimidazole ) or a combination thereof.

[0128] The twenty-ninth embodiment may include the twenty-eighth embodiment, which further contains crotonic acid.

[0129] The thirtieth embodiment may include the twenty-eighth or twenty-ninth embodiment, which further contains a non-polymeric cationic compound selected from the following: diallyldimethylammonium, methacryloyloxyethyltrimethylammonium, lysine, 2-(dimethylamino)ethyl methacrylate, or a mixture thereof.

[0130] The thirty-first embodiment may include the thirtieth embodiment, which contains at least 250 ppm by weight of a self-stopper, at least 20 ppm by weight of a cationic polymer, and at least 20 ppm by weight of a non-polymeric cationic compound.

[0131] The thirty-second embodiment includes a method of chemical mechanical polishing of a substrate including a silicon oxide dielectric material. The method includes: (a) providing a polishing composition including any one of the first to thirty-first embodiments; (b) bringing the substrate into contact with the provided polishing composition; (c) moving the polishing composition relative to the substrate; and (d) grinding the substrate to remove a portion of the silicon oxide dielectric material from the substrate and thereby polish the substrate.

[0132] The thirty-third embodiment may include the thirty-second embodiment, wherein in (d), the effective removal of the silicon oxide dielectric material in the patterned area of the substrate has a trench loss removal of the silicon oxide dielectric material greater than about 5.

[0133] The thirty-fourth embodiment may include any one of the thirty-second to thirty-third embodiments, wherein: the self-stopper is phenylhydroxamic acid, salicylhydroxamic acid, kojic acid, potassium sorbate, or a combination thereof; the cationic polymer is poly(vinylimidazole ), poly(methacryloyloxyethyltrimethylammonium), polylysine, poly(diallyldimethylammonium), or a combination thereof; and the polishing composition further contains picolinic acid, acetic acid, 4-hydroxybenzoic acid, or a mixture thereof.

[0134] The thirty-fifth embodiment may include any one of the thirty-second to thirty-third embodiments, wherein: the self-stopper is phenylhydroxamic acid, salicylhydroxamic acid, or a combination thereof; and the cationic polymer is ε-poly-L-lysine, poly(vinylimidazole ), or a combination thereof.

[0135] The thirty-sixth embodiment may include the thirty-second, thirty-third, or thirty-fifth embodiment, wherein the polishing composition further contains a non-polymeric cationic compound selected from the following: diallyldimethylammonium, methacryloyloxyethyltrimethylammonium, lysine, 2-(dimethylamino)ethyl methacrylate, or a mixture thereof.

[0136] The thirty-seventh embodiment may include the thirty-fifth or thirty-sixth embodiment, wherein in (d), the effective removal of the silicon oxide dielectric material in the patterned region of the substrate results in a trench loss removal of the silicon oxide dielectric material that is greater than about 50.

[0137] The thirty-eighth embodiment may include any one of the thirty-second to thirty-seventh embodiments, wherein providing the polishing composition includes: (i) providing a polishing concentrate and (ii) diluting the polishing concentrate with at least one part of water per part of the polishing concentrate to obtain the polishing composition.

[0138] The thirty-ninth embodiment may include any one of the thirty-second to thirty-seventh embodiments, wherein providing the polishing composition includes: (i) providing a first and a second pack, the first pack including cubic ceria abrasive grains and the second pack including a self-stopping agent and a cationic polymer; and (ii) combining the first and second packs to obtain the polishing composition.

[0139] The fortieth embodiment may include the thirty-ninth embodiment, wherein in (ii), at least one of the first and second packs is diluted with water before combination.

[0140] The present invention includes the following aspects / embodiments / features in any order and / or any combination:

[0141] 1. A chemical mechanical polishing composition comprising:

[0142] A liquid carrier;

[0143] Cubic ceria abrasive grains dispersed in the liquid carrier;

[0144] A self-stopping agent; and

[0145] A cationic polymer.

[0146] 2. The composition of any of the foregoing or following embodiments / features / aspects, wherein the cubic ceria abrasive grains comprise a mixture of cerium oxide and lanthanum oxide.

[0147] 3. The composition of any of the foregoing or following embodiments / features / aspects, wherein the cubic ceria abrasive grains have a molar ratio of lanthanum to lanthanum + cerium in the range of about 1% to about 15%.

[0148] 4. The composition of any of the foregoing or following embodiments / features / aspects, wherein the cubic ceria abrasive grains have a BET surface area in the range of about 3 m 2 / g to about 14 m 2 / g.

[0149] 5. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the cubic ceria abrasive particles have an average particle size in the range of about 50 to about 500 nm.

[0150] 6. A composition of any of the foregoing or subsequent embodiments / features / aspects, comprising from about 0.01 weight percent to about 1 weight percent of the cubic ceria abrasive particles.

[0151] 7. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the self-stopper is a ligand attached to the cubic ceria abrasive particles.

[0152] 8. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the self-stopper is kojic acid, maltol, ethyl maltol, propyl maltol, hydroxamic acid, benzhydroxamic acid, salicylhydroxamic acid, benzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, sorbic acid, potassium sorbate, and combinations thereof.

[0153] 9. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the self-stopper is benzhydroxamic acid, salicylhydroxamic acid, kojic acid, potassium sorbate, or combinations thereof.

[0154] 10. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the cationic polymer is selected from: poly(vinylimidazole ), poly(vinylimidazole),), poly(vinylimidazole), methacryloyloxyethyltrimethylammonium, poly(diallyldimethylammonium), polyquaternium-2, polyquaternium-11, polyquaternium-16, polyquaternium-46, polyquaternium-44, polylysine, and combinations thereof.

[0155] 11. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the cationic polymer is poly(vinylimidazole ),), poly(vinylimidazole), methacryloyloxyethyltrimethylammonium, polylysine, or combinations thereof.

[0156] 12. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein

[0157] the use-point concentration of the cubic ceria abrasive particles is from about 0.01 weight percent to about 1 weight percent;

[0158] the use-point concentration of the self-stopper is from about 200 weight ppm to about 5000 weight ppm; and

[0159] the use-point concentration of the cationic polymer is from about 5 weight ppm to about 500 weight ppm.

[0160] 13. A composition of any of the foregoing or subsequent embodiments / features / aspects further comprises a carboxylic acid rate enhancer.

[0161] 14. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the carboxylic acid rate enhancer is picolinic acid, acetic acid, 4-hydroxybenzoic acid, or a mixture thereof.

[0162] 15. A composition of any of the foregoing or subsequent embodiments / features / aspects further comprises an unsaturated carboxyl monobasic acid rate inhibitor selected from the group consisting of acrylic acid, crotonic acid, 2-pentenoic acid, trans-2-hexenoic acid, trans-3-hexenoic acid, 2-hexynoic acid, 2,4-hexadienoic acid, potassium sorbate, trans-2-methyl-2-butenoic acid, 3,3-dimethylacrylic acid, and combinations thereof.

[0163] 16. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the unsaturated carboxyl monobasic acid rate inhibitor is crotonic acid.

[0164] 17. A composition of any of the foregoing or subsequent embodiments / features / aspects further comprises a non-polymeric cationic compound selected from the group consisting of 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 3-(dimethylamino)propyl methacrylamide, 3-(dimethylamino)propyl acrylamide, lysine, 3-methacrylamidopropyl-trimethyl-ammonium, 3-acrylamidopropyl-trimethyl-ammonium, diallyldimethylammonium, 2-(acryloyloxy)-N,N,N-trimethylethylammonium, methacryloyloxyethyl trimethylammonium, N,N-dimethylaminoethyl phenyl acrylate, N,N-dimethylaminoethyl phenyl methacrylate, and combinations thereof.

[0165] 18. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the non-polymeric cationic compound comprises diallyldimethylammonium, methacryloyloxyethyl trimethylammonium, lysine, 2-(dimethylamino)ethyl methacrylate, or a mixture thereof.

[0166] 19. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the cationic polymer comprises polylysine and the non-polymeric compound comprises diallyldimethylammonium.

[0167] 20. A composition of any of the foregoing or subsequent embodiments / features / aspects further comprises triethanolamine.

[0168] 21. A composition of any of the foregoing or subsequent embodiments / features / aspects further comprises benzotriazole or bitrimethane.

[0169] 22. A composition of any of the foregoing or subsequent embodiments / features / aspects having a pH in the range of about 5 to about 10.

[0170] 23. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein:

[0171] the self-stopping agent is benzohydroxamic acid, salicylhydroxamic acid, kojic acid, potassium sorbate, or a combination thereof;

[0172] the cationic polymer is poly(vinylimidazole ), poly(methacryloyloxyethyltrimethylammonium), polylysine, poly(diallyldimethylammonium), or a combination thereof; and

[0173] the composition further comprises picolinic acid, acetic acid, 4-hydroxybenzoic acid, or a mixture thereof.

[0174] 24. A composition of any of the foregoing or subsequent embodiments / features / aspects, further comprising triethanolamine and benzotriazole.

[0175] 25. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the self-stopping agent is benzohydroxamic acid, salicylhydroxamic acid, or a combination thereof, and the pH at the point of use is in the range of about 7 to about 9.

[0176] 26. A composition of any of the foregoing or subsequent embodiments / features / aspects, comprising at least 250 weight ppm of the self-stopping agent at the point of use and 50 weight ppm of the cationic polymer at the point of use.

[0177] 27. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein the self-stopping agent is kojic acid, potassium sorbate, or a combination thereof, and the pH at the point of use is in the range of about 5 to about 6.5.

[0178] 28. A composition of any of the foregoing or subsequent embodiments / features / aspects, wherein:

[0179] the self-stopping agent is benzohydroxamic acid, salicylhydroxamic acid, or a combination thereof; and

[0180] the cationic polymer is ε-poly-L-lysine, poly(vinylimidazole ) or a combination thereof.

[0181] 29. A composition of any of the foregoing or subsequent embodiments / features / aspects, further comprising crotonic acid.

[0182] 30. The composition of any of the foregoing or subsequent embodiments / features / aspects further comprises a non-polymeric cationic compound selected from: diallyldimethylammonium, methacryloyloxyethyltrimethylammonium, lysine, 2-(dimethylamino)ethyl methacrylate, or mixtures thereof.

[0183] 31. The composition of any of the foregoing or subsequent embodiments / features / aspects, comprising:

[0184] at least 250 ppm by weight of the self-stopper;

[0185] at least 20 ppm by weight of the cationic polymer; and

[0186] at least 20 ppm by weight of the non-polymeric cationic compound.

[0187] 32. A method of chemically mechanical polishing a substrate comprising a silicon oxide dielectric material, the method comprising:

[0188] (a) providing a polishing composition comprising: a liquid carrier; cubic ceria abrasive particles dispersed in the liquid carrier; a self-stopper; and a cationic polymer;

[0189] (b) contacting the substrate with the provided polishing composition;

[0190] (c) moving the polishing composition relative to the substrate; and

[0191] (d) abrading the substrate to remove a portion of the silicon oxide dielectric material from the substrate and thereby polish the substrate.

[0192] 33. The method of any of the foregoing or subsequent embodiments / features / aspects, wherein in (d), the effective removal of the silicon oxide dielectric material in the patterned area of the substrate results in a trench loss removal of the silicon oxide dielectric material greater than about 5.

[0193] 34. The method of any of the foregoing or subsequent embodiments / features / aspects, wherein:

[0194] the self-stopper is phenylhydroxamic acid, salicylhydroxamic acid, kojic acid, potassium sorbate, or a combination thereof;

[0195] the cationic polymer is poly(vinylimidazole ), poly(methacryloyloxyethyltrimethylammonium), polylysine, poly(diallyldimethylammonium), or a combination thereof; and

[0196] the polishing composition further comprises picolinic acid, acetic acid, 4-hydroxybenzoic acid, or a mixture thereof.

[0197] 35. A method according to any of the foregoing or subsequent embodiments / features / aspects, wherein:

[0198] The self-stopping agent is phenylhydroxamic acid, salicylhydroxamic acid, or a combination thereof;

[0199] The cationic polymer is ε-poly-L-lysine, poly(vinylimidazole ) or a combination thereof.

[0200] 36. A composition according to any of the foregoing or subsequent embodiments / features / aspects, wherein the polishing composition further comprises a non-polymeric cationic compound selected from: diallyldimethylammonium, methacryloyloxyethyltrimethylammonium, lysine, 2-(dimethylamino)ethyl methacrylate, or a mixture thereof.

[0201] Various substrates are polished using an Applied Materials Mirra® polishing tool (available from Applied Materials, Inc.). A blanketed wafer is polished on the Mirra® for 60 seconds at a platen speed of 100 rpm, a head speed of 85 rpm, a downforce of 3 psi, and a slurry flow rate of 150 ml / min. A patterned wafer is polished for 80 seconds under the same conditions. The wafers are polished on a NexPlanar® E6088 pad (available from Cabot Microelectronics Corporation), where in-situ conditioning is performed at a 6-pound downforce using a Saesol DS8051 conditioner.

[0202] In the following examples, blanketed tetraethyl orthosilicate (TEOS), blanketed SiN, and patterned TEOS wafers are polished. The blanketed TEOS wafers are obtained from WRS Materials and include a 20 kÅ TEOS layer. The blanketed SiN wafers are obtained from Advantec and include a 5 kÅ PE SiN layer. The patterned TEOS wafers are Silyb and STI1 10kÅ TEOS pattern wafers.

[0203] Example 1

[0204] A raw cerium oxide dispersion is prepared as follows. A cerium nitrate solution is prepared by combining 13.1 kg of a 3 M cerium(III) nitrate solution, 0.3 kg of a 3 M lanthanum nitrate solution, 2.0 kg of a 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 equal to 0.000055. The cerium nitrate solution is then degassed in a 20 L container with stirring and nitrogen bubbling.

[0205] An aqueous ammonia solution was prepared by combining 75 kg of deionized water and 13.1 kg of 25% aqueous ammonia solution (such that the molar ratio of NH₄OH in the aqueous ammonia solution to the total amount of cerium and lanthanum in the cerium nitrate solution was 9.0). Subsequently, the aqueous ammonia solution was degassed in a 100 L vessel jacket reactor under stirring and nitrogen bubbling.

[0206] Subsequently, at ambient temperature, under nitrogen purge and with the same stirring, the cerium nitrate solution was added to the aqueous ammonia solution. Subsequently, the temperature of the reaction mixture was raised to 80 °C and maintained at this temperature for 18 hours. Subsequently, the reaction mixture was cooled and acidified to pH 2 by adding 68% nitric acid after cooling.

[0207] Subsequently, the reaction mixture was filtered and washed with deionized water. Washing was repeated when the conductivity of the washing solution was less than 0.04 mS / cm. Deionized water was added to adjust the final cerium oxide concentration to 10 wt%. The cubic ceria abrasive particles comprise 2.5 mol% of lanthanum oxide and 97.5 mol% of cerium oxide.

[0208] The BET specific surface area was determined by nitrogen adsorption to be 11.8 m² / g. The average particle size measured by Horiba 960 was 102 nm, and the average particle size measured by Malvern Zetasizer was 140 nm.

[0209] Example 2

[0210] Two polishing compositions were tested to evaluate the TEOS polishing rate and self-stopping behavior on blanket and patterned wafers. Each composition was prepared by combining a first package (Package A) with deionized water and the corresponding second package (Package B). Package A comprised 3500 wt ppm picolinic acid, 75 wt ppm Kordex MLX, and 2 wt% of the ceria abrasive at pH 4.0. For Composition 2A, the ceria abrasive comprised 2 wt% of a control ceria (the sintered ceria abrasive used in Polishing Composition 1C of co-owned US Patent 9,505,952). For Composition 2B, the ceria abrasive comprised 1 part by weight of the raw ceria dispersion described in Example 1 above and 4 parts by weight of deionized water to obtain 2 wt% of cubic ceria. Package B was the same and comprised 4000 wt ppm triethanolamine, 1600 wt ppm benzotriazole, 250 wt ppm polyMADQUAT, 1670 wt ppm benzyhydroxamic acid, and 113 wt ppm of Kordex MLX at pH 8.2.

[0211] First, combine one portion of Package A with six portions of deionized water and then further combine with three portions of Package B to obtain a point-of-use composition that includes 0.2 weight percent ceria abrasive, 350 weight ppm picolinic acid, 1200 weight ppm triethanolamine, 480 weight ppm benzotriazole, and 75 weight ppm polyMADQUAT. The pH of the combined Package A and Package B is about 7.8

[0212] Under the conditions listed above, polish a blanket TEOS wafer on a Mirra® tool for 60 seconds. The blanket TEOS removal rate is shown in Table 1 in angstroms per minute (Å / min). Polish a patterned wafer on a Mirra® tool for 80 seconds under the same conditions. The results (trench loss, effective removal, and step height) for the patterned wafer are also shown in Table 1. List the step heights of two pattern features in angstroms (Å) (where the first number refers to the line width in microns and the second number refers to the pattern density).

[0213] Table 1

[0214]

[0215] As is clear from the results set forth in Table 1, the composition (2B) that includes cubic ceria abrasive particles achieves a 65% improvement in effective removal and improved step heights (especially in terms of dense features). However, these improvements are offset by an almost 10× increase in trench loss. Due to the high blanket removal rate and high trench loss, therefore, composition 2B (including cubic ceria abrasive particles) is not a self-stopping composition. Based on this example, one of ordinary skill in the art would readily understand that due to the complex interactions between the ceria abrasive and the composition chemistry, in a self-stopping CMP composition, conventional wet ceria abrasive particles (such as in 2A) cannot be swapped out with cubic ceria abrasive particles (such as in 2B).

[0216] Example 3

[0217] Test ten polishing compositions to evaluate the TEOS polish rate and self-stopping behavior on a patterned wafer. Select ten polishing compositions (3A - 3J) to vary the cationic polymer content and type and compare with control composition 1A. Prepare each composition by combining Package A with deionized water and the corresponding Package B. Each Package A includes 3500 weight ppm picolinic acid, 75 weight ppm Kordex MLX, and 20 weight percent of the ceria dispersion described in Example 1 above (total ceria concentration in Package A is 2 weight percent).

[0218] The B packet contains 4000 weight ppm triethanolamine, 1600 weight ppm benzotriazole, a cationic polymer, 1670 weight ppm benzyhydroxamic acid, and 113 weight ppm of Kordex MLX at pH 8.2. The types and amounts of the cationic polymer are listed in Table 2A below.

[0219] Table 2A

[0220]

[0221] First, one packet of A is hydrated with 6 parts of deionized water and then further combined with 3 parts of B to obtain a point-of-use composition, which includes 0.2 weight percent ceria abrasive, 350 weight ppm picolinic acid, 1200 weight ppm triethanolamine, 500 weight ppm benzyhydroxamic acid, and 480 weight ppm benzotriazole. The point-of-use amount of the cationic polymer is 30% of the amounts listed in Table 2A. The pH of the combined A and B packets is about 7.8

[0222] Under the conditions listed above, a blanket TEOS wafer is polished on a Mirra® tool for 60 seconds. The blanket TEOS removal rate is shown in Table 2B in angstroms per minute (Å / min). A patterned wafer is polished on a Mirra® tool for 80 seconds under the same conditions. The results (trench loss, effective removal, and step height) for the patterned wafer are also shown in Table 2B. The step heights for the two patterns are listed in angstroms (Å) (where the first number refers to the line width in microns and the second number refers to the pattern density).

[0223] Table 2B

[0224]

[0225] As is clear from the results set forth in Table 2B, Compositions 3B and 3E, which include polyMADQUAT and polyquaternium-44 cationic polymers, provide excellent self-stopping performance. In addition, Compositions 3C, 3F, and 3J provide excellent ratios of effective removal rate to both blanket removal rate and trench loss. With minor modifications, these compositions can also provide excellent self-stopping performance.

[0226] Example 4

[0227] Eight polishing compositions were tested to evaluate the TEOS polish rate and the self-stop behavior on patterned wafers. Eight polishing compositions (4A - 4H) were selected to vary the self-stop agent content and type and were compared to a control composition 2A. Each composition was prepared by combining a Package A with deionized water and the corresponding Package B. Each Package A included 3500 weight ppm picolinic acid, 75 weight ppm Kordex MLX, and 20 weight percent of the ceria dispersion described in Example 1 above (total ceria concentration in Package A was 2 weight percent).

[0228] Package B included 4000 weight ppm triethanolamine, 1600 weight ppm benzotriazole, 250 weight ppm polyMADQUAT, the self-stop agent, and 113 weight ppm Kordex MLX. The self-stop agent type and amount are listed in Table 3A below.

[0229] Table 3A

[0230]

[0231] First, one part of Package A was combined with six parts of deionized water and then further combined with three parts of Package B to obtain the use-point composition, which included 0.2 weight percent ceria abrasive, 350 weight ppm picolinic acid, 1200 weight ppm triethanolamine, 75 weight ppm polyMADQUAT, and 480 weight ppm benzotriazole. The use-point amount of the self-stop agent was 30% of the amounts listed in Table 3A. For compositions 4A - 4D, the pH of the combined Package A and B was approximately 7.8 and for compositions 4E - 4H, the pH of the combined Package A and B was approximately 5.5.

[0232] Under the conditions listed above, blanket TEOS wafers were polished on a Mirra® tool for 60 seconds. The blanket TEOS removal rate is shown in Table 3B in angstroms per minute (Å / min). Patterned wafers were polished on a Mirra® tool for 80 seconds under the same conditions. The results for the patterned wafers (trench loss, effective removal, and step height) are also shown in Table 3B. The step heights for the two patterns are listed in angstroms (Å) (where the first number refers to the line width in microns and the second number refers to the pattern density).

[0233] Table 3B

[0234]

[0235] As is clear from the results set forth in Table 3B, compositions 4B, 4D, and 4H including phenylhydroxamic acid, salicylhydroxamic acid, and potassium sorbate as self-stopping agents provide excellent self-stopping performance. In addition, composition 4F (using kojic acid as a self-stopping agent) provides an excellent ratio of effective removal rate to blanket removal rate and trench loss. With minor modifications, this composition can also provide excellent self-stopping performance.

[0236] Example 5

[0237] Two polishing compositions were tested to evaluate the TEOS polishing rate and self-stopping behavior on blanket and patterned wafers. Each composition was prepared by combining a Package A with deionized water and the corresponding Package B. Package A included 3500 weight ppm picolinic acid, 75 weight ppm Kordex MLX, and 2 weight percent ceria abrasive at pH 4.0. For composition 5A, the ceria abrasive included 2 weight percent control ceria (the sintered ceria abrasive used in polishing composition 1C of commonly assigned U.S. Patent 9,505,952). For composition 5B, the ceria abrasive included 1 part by weight of the raw ceria dispersion described in Example 1 above and 4 parts by weight of deionized water. Package B was the same and included 4000 weight ppm triethanolamine, 1600 weight ppm benzotriazole, 250 weight ppm polyMADQUAT, 3340 weight ppm potassium sorbate, and 113 weight ppm of Kordex MLX at pH 6.

[0238] First, one part of Package A was combined with 6 parts of deionized water and then further combined with 3 parts of Package B to obtain a point-of-use composition that included 0.2 weight percent ceria abrasive, 350 weight ppm picolinic acid, 1200 weight ppm triethanolamine, 480 weight ppm benzotriazole, 1000 weight ppm potassium sorbate, and 75 weight ppm polyMADQUAT. The pH of the combined Package A and Package B was approximately 5.5

[0239] Under the conditions listed above, a blanket TEOS wafer was polished on a Mirra® tool for 60 seconds. The blanket TEOS removal rate is shown in Table 4 in angstroms per minute (Å / min). A patterned wafer was polished on a Mirra® tool for 80 seconds under the same conditions. The results for the patterned wafer (trench loss, effective removal, and step height) are also shown in Table 4.

[0240] Table 4

[0241]

[0242] As is clear from the results set forth in Table 4, the composition (2B) comprising cubic ceria abrasive particles achieves excellent self-stopping performance, where the ratio of effective removal to blanket removal is greater than 12 and the step height on dense features is less than 400 Å. In contrast, the composition using the control ceria abrasive exhibits a very low removal rate and does not provide planarization of the patterned wafer.

[0243] Example 6

[0244] Six polishing compositions were tested to evaluate the effective loss in various patterns on a patterned wafer. As is known to those of ordinary skill in the art, effective loss is defined as the effective thickness before polishing minus the effective thickness after polishing. The polishing compositions were the same as compositions 2A, 3B, 3E, 4B, 4D, and 4H. As indicated above, composition 2B included the control ceria abrasive, while compositions 3B, 3E, 4B, 4D, and 4H included cubic ceria abrasive particles. The effective loss was plotted in Å relative to Figure 4 the pattern type.

[0245] As is clear from the Figure 4 results set forth in, the compositions comprising cubic ceria abrasive particles achieve excellent planarization, as defined by a greater effective loss within a wide range of pattern densities. Additionally, the compositions comprising cubic ceria abrasive particles also achieve excellent planarization, as defined by the difference between the maximum plotted effective loss and the minimum plotted effective loss within the range of pattern densities. Without wishing to be bound by theory, it is believed that the cubic ceria abrasive particles perform well in the presence of a higher concentration of self-stopping agent and / or cationic polymer and thus achieve excellent planarization.

[0246] Example 7

[0247] Two polishing compositions were tested to evaluate the TEOS and SiN polishing rates and self-stopping behavior on blanket and patterned wafers. Each of compositions 7A, 7B, and 7C was prepared by combining the abrasive formulation (package A) and the corresponding additive formulation (package B) in a 7:3 volume ratio. The use-point pH of each composition was 6.2. The composition of the abrasive formulation (package A) is shown in Table 5A, while the composition of the additive formulation (package B) is shown in Table 5B. All compositions are by weight (e.g., weight percent or weight ppm).

[0248] Table 5A

[0249]

[0250] Table 5B

[0251]

[0252] At a platen speed of 73 rpm, a head speed of 67 rpm, a downforce of 3.5 psi, and a slurry flow rate of 250 ml / min, blanket TEOS and SiN wafers were polished for 60 seconds on an Applied Materials Reflexion® tool using a DuPont IC1010® pad. The blanket TEOS and SiN removal rates are shown in Table 5C in angstroms per minute (Å / min). Patterned wafers were polished on the Reflexion® tool for 20 seconds under the same conditions. The results (trench loss and effective removal) for the patterned wafers are also shown in Table 5C.

[0253] Table 5C

[0254]

[0255] As is clear from the data set forth in Table 5C, Composition 7B exhibits excellent self-stopping performance with a high effective removal (almost 4000 Å) and a very low blanket removal rate, resulting in an effective removal to blanket removal ratio of almost 100 and an effective removal to trench loss ratio of 14. Although having a lower effective removal, Composition 7C also exhibits excellent self-stopping performance. Composition 7C achieves an effective removal to blanket removal ratio and an effective removal to trench loss ratio greater than 100.

[0256] Example 8

[0257] Three polishing compositions were tested to evaluate the effect of the lanthanum doping level in cubic ceria abrasive particles on the TEOS removal rate. Composition 8A includes 0.28 weight percent of a control ceria (wet oxidized ceria HC60™ available from Rhodia). Composition 8B includes 0.28 weight percent of cubic ceria abrasive particles comprising 2.5 mole % lanthanum oxide and was prepared by diluting the starting ceria dispersion described in Example 1 above with 34 parts of water to 1 part of the starting ceria dispersion. Composition 8C includes 0.28 weight percent of cubic ceria abrasive particles comprising 10 mole % lanthanum oxide and was prepared by diluting the ceria dispersion described in the following paragraph with 34 parts of water to 1 part of the ceria dispersion. The pH of each of Compositions 8A - 8C is 4.

[0258] The ceria dispersion was prepared as follows. A cerium nitrate solution was prepared by combining 11.5 kg of a 3M cerium(III) nitrate solution, 1.3 kg of a 3M lanthanum nitrate solution, 1.86 kg of a 68% nitric acid (HNO3) solution, 0.5 kg of deionized water, and cerium(IV) nitrate at a cerium(IV) to cerium(total) molar ratio equal to 0.0000125 (1 / 80,235). The cerium nitrate solution was then degassed in a 20 L container with stirring and nitrogen bubbling.

[0259] An aqueous ammonia solution was prepared by combining 70 kg of deionized water and 14 kg of 25% aqueous ammonia solution (such that the molar ratio of NH4OH in the aqueous ammonia solution to the total amount of cerium and lanthanum in the cerium nitrate solution was 10). The aqueous ammonia solution was then degassed in a 100 L vessel jacket reactor with stirring and nitrogen bubbling.

[0260] Then, at ambient temperature, with nitrogen purging and under the same stirring, the cerium nitrate solution was added to the aqueous ammonia solution. Then the temperature of the reaction mixture was raised to 88 °C and maintained at that temperature for 13.5 hours. Then the reaction mixture was cooled and acidified to pH 2 by adding 68% nitric acid after cooling.

[0261] Then the reaction mixture was filtered and washed with deionized water. Washing was repeated when the conductivity of the wash solution was less than 0.04 mS / cm. Deionized water was added to adjust the final concentration of cubic ceria abrasive to 10 weight percent. The cubic ceria abrasive particles comprise 10 mole percent lanthanum oxide and 90 mole percent cerium oxide.

[0262] The BET specific surface area was determined by nitrogen adsorption to be 8.6 m2 / g. The average particle size measured by a Malvern Zetasizer was 142 nm.

[0263] Under the conditions listed above, a blanketed TEOS wafer was polished on a Mirra® tool for 60 seconds. The polishing results are shown in Table 6. All removal rates (RR) are listed in angstroms per minute (Å / min).

[0264] Table 6

[0265]

[0266] As is clear from the data set forth in Table 5, Compositions 8B and 8C exhibit equivalent TEOS removal rates that are 1.6× the removal rate of Composition 8A.

[0267] In describing the scope of the present invention, particularly the scope of the appended claims, the terms "a", "an", "the", and similar referents shall be understood to include both the singular and the plural, unless otherwise specified herein or the context clearly dictates otherwise. The terms "comprising", "having", "including", and "containing" shall be understood to be open-ended terms (i.e., meaning "including, but not limited to") unless otherwise noted. The recitation of numerical ranges herein is merely a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by the context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein is merely to better illuminate the invention and is not intended to limit the scope of the invention, unless otherwise indicated. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0268] Preferred embodiments of the invention are described herein, including the best mode known to the inventors for practicing the invention. Variations of those preferred embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect those skilled in the art to appropriately employ such variations, and the inventors expect the invention to be practiced otherwise than as specifically described herein. Accordingly, the invention includes all modifications and equivalents of the subject matter recited in the appended claims as permitted by applicable law. In addition, the invention covers any combination of the above elements in all possible variations thereof, unless otherwise indicated herein or clearly contradicted by the context.

[0269] It is understood that the present invention includes many embodiments other than those embodiments included in the above examples. These embodiments include (but are not limited to) the embodiments recited in the claims.

Claims

1. A method of chemical mechanical polishing of a substrate comprising a silicon oxide dielectric material, the method comprising: (a) providing a polishing composition comprising: a liquid carrier; cubic ceria abrasive particles dispersed in the liquid carrier; a self-stopping agent; and a cationic polymer, wherein the cubic ceria abrasive particles comprise a mixture of cerium oxide and lanthanum oxide, and wherein the self-stopping agent is kojic acid, maltol, ethyl maltol, propyl maltol, hydroxamic acid, phenylhydroxamic acid, salicylhydroxamic acid, benzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, sorbic acid, potassium sorbate, and combinations thereof; (b) contacting the substrate with the provided polishing composition; (c) moving the polishing composition relative to the substrate; and (d) abrading the substrate to remove a portion of the silicon oxide dielectric material from the substrate and thereby polish the substrate.

2. The method of claim 1, wherein In (d), the ratio of effective removal of the silicon oxide dielectric material in the patterned area of the substrate to removal of trench loss of the silicon oxide dielectric material is greater than about 5.

3. The method of claim 1, wherein: the self-stopping agent is phenylhydroxamic acid, salicylhydroxamic acid, kojic acid, potassium sorbate, or a combination thereof; The cationic polymer is poly(vinylimidazole ), poly(methacryloyloxyethyltrimethylammonium), polylysine, poly(diallyldimethylammonium), or a combination thereof; and the polishing composition further comprises picolinic acid, acetic acid, 4-hydroxybenzoic acid, or a mixture thereof.

4. The method of claim 1, wherein: the self-stopping agent is phenylhydroxamic acid, salicylhydroxamic acid, or a combination thereof; The cationic polymer is ε-poly-L-lysine, poly(vinylimidazole ), or a combination thereof.

5. The method of claim 4, wherein the polishing composition further comprises a non-polymeric cationic compound selected from: diallyldimethylammonium, methacryloyloxyethyltrimethylammonium, lysine, 2-(dimethylamino)ethyl methacrylate, or a mixture thereof.

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