CMP slurry

Abstract

To provide, in general, compositions and methods for polishing surfaces comprising a metal and a dielectric film material.SOLUTION: Embodiments include: methods for polishing a surface comprising W, TEOS / SiO2 and SiN, comprising supplying polishing slurry comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant; and methods of buffering a metal oxide salt in CMP slurry to obtain increased robustness against TEOS removal, comprising polishing a surface comprising a metal and TEOS by supplying polishing slurry comprising an anionic modified colloidal silica abrasive and an anionic surfactant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present technology relates generally to compositions and methods for polishing surfaces including metal and dielectric film materials. [Background technology]

[0002] Silicon nitride (SiN) chemical mechanical polishing (CMP) slurries are used in a wide range of applications.

[0003] Additionally, tungsten (W) can be part of a patterned wafer. Summary of the Invention [Problem to be solved by the invention]

[0004] Provided herein are novel compositions and novel methods for polishing surfaces including metal and dielectric film materials. [Means for solving the problem]

[0005] Certain aspects of the present disclosure include a method for polishing a surface comprising W, TEOS / SiO2, and SiN, comprising providing a polishing slurry comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant. In some embodiments, the abrasive is an anionic modified colloidal silica using a sulfonate chemical. In some embodiments, the anionic modified colloidal silica is treated with a sulfonate chemical. In some embodiments, the polishing slurry has an electrical conductivity value of less than 300 μS / cm. In some embodiments, the polishing slurry has an electrical conductivity value of greater than 100 μS / cm. In some embodiments, the polishing slurry has a pH of about 4 to about 5. In some embodiments, the SiN polishing rate enhancer is selected from the group consisting of amino acids and heterocyclic carbon compounds. In some embodiments, the anionic surfactant is selected from sulfonic acid surfactants. In some embodiments, the amount of SiN polishing rate enhancer is about 0.05 to about 0.5 wt. %. In some embodiments, the amount of abrasive is about 0.8 wt. % or less. In some embodiments, the ratio of SiN removal to TEOS removal during polishing is greater than about 40:1. In some embodiments, polishing is performed with WO4 2- Here, TEOS means tetraethyl orthosilicate, and TEOS / SiO2 indicates that the silicon oxide (SiO2) is a silicon oxide film derived from tetraethyl orthosilicate.

[0006] Certain aspects of the present disclosure include a method for buffering metal oxide salts in a CMP slurry to enhance robustness against TEOS removal, comprising polishing a surface containing metal and TEOS by providing a polishing slurry containing an anionic modified colloidal silica abrasive and an anionic surfactant. In some embodiments, the polishing slurry has an electrical conductivity value of less than 300 μS / cm. In some embodiments, the metal is W and the metal oxide salt is WO4 2- In some embodiments, the surface further comprises SiN, and the polishing slurry further comprises a SiN polishing rate enhancer. In some embodiments, the polishing slurry has a pH of about 4 to about 5.

[0007] Certain aspects of the present disclosure include CMP compositions comprising an anionic modified colloidal silica abrasive, a SiN polishing rate enhancer, and an anionic surfactant, wherein the anionic modified colloidal silica abrasive is present in an amount of 1 wt % or less and the ratio of abrasive to SiN polishing rate enhancer is within the range of about 1.5-1 to about 1.9-1. In some embodiments, the CMP composition has a pH of about 4 to about 5. In some embodiments, the SiN polishing rate enhancer is β-alanine.

[0008] A particular embodiment of the present disclosure is a method for polishing a surface comprising W, TEOS / SiO2, and SiN, the method comprising providing a polishing slurry comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant, the polishing slurry having an electrical conductivity value of 100 μS / cm to 350 μS / cm.

[0009] A specific embodiment of the present disclosure is a method for buffering metal oxide salts in a CMP slurry to enhance robustness against TEOS removal, comprising polishing a surface containing metal and TEOS by providing a polishing slurry containing an anionic-modified colloidal silica abrasive and an anionic surfactant, the polishing slurry having an electrical conductivity value of 100 μS / cm to 350 μS / cm. A specific embodiment of the present disclosure is a CMP composition containing an anionic-modified colloidal silica abrasive, a SiN polishing rate enhancer, and an anionic surfactant, the anionic-modified colloidal silica abrasive being present in an amount of 1 wt % or less, the ratio of abrasive to SiN polishing rate enhancer being within the range of about 1.5-1 to about 1.9-1, and the CMP composition having an electrical conductivity value of 100 μS / cm to 350 μS / cm. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows the effect of K2WO4 on TEOS removal rate and electrical conductivity (EC) for a particular CMP composition. [Figure 2]FIG. 2 shows the effect of K2WO4 on TEOS removal rate and electrical conductivity (EC) for additional specific CMP compositions. DETAILED DESCRIPTION OF THE INVENTION

[0011] Provided herein are CMP compositions and methods for polishing surfaces, including metal and dielectric film materials. As used herein, the term "chemical-mechanical polishing" or "planarization" refers to a process of planarizing (polishing) a surface through a combination of surface chemical reaction and mechanical abrasion. In some embodiments, the chemical reaction is initiated by supplying the surface with a composition (interchangeably referred to as a "polishing (CMP) slurry," "CMP composition," "polishing composition," "slurry composition," or simply "slurry") that can react with the surface material, thereby reducing the surface material to products that can be more easily removed by simultaneous mechanical abrasion. In some embodiments, the mechanical abrasion is performed by contacting a polishing pad with the surface and moving the polishing pad relative to the surface.

[0012] composition The CMP polishing composition disclosed herein can comprise, consist essentially of, or consist of one or more of the following components: Here, "consist essentially of" means that the CMP polishing composition may contain up to 0.001 wt % of components not intended to be added to the composition (components other than those listed below), for example.

[0013] abrasives The CMP composition of the present disclosure contains at least one abrasive. The abrasive in the CMP composition provides or enhances the mechanical polishing effect during the CMP process. Examples of abrasives that can be used in connection with the present disclosure include, but are not limited to, alumina abrasives, silica abrasives, ceria abrasives, titanium oxide, zirconia, or mixtures thereof.

[0014] In some embodiments, the abrasive is an anionic-modified colloidal silica. In some embodiments, the anionic-modified colloidal silica is modified using a sulfonate chemical. Thus, in some embodiments, the CMP composition includes an anionic-modified colloidal silica containing anionic groups (e.g., sulfonic acid groups) attached to the surface of raw colloidal silica particles. In some embodiments, anionic-modified colloidal silica modified using a sulfonate chemical can be prepared, for example, by the method described in "Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups," Chem. Commun. 246-247 (2003). Specifically, silica having sulfonic acid immobilized on its surface can be obtained by coupling a silane coupling agent having a thiol group, such as 3-mercaptopropyltrimethoxysilane, to silica and then oxidizing the thiol group with hydrogen peroxide.

[0015] The raw colloidal silica may be, for example, colloidal silica produced by the sol-gel method. The production of raw colloidal silica by the sol-gel method can be carried out using conventionally known techniques. Specifically, raw colloidal silica can be obtained by hydrolysis and condensation reactions using a hydrolyzable silicon compound (e.g., an alkoxysilane or its derivative) as a raw material. The silicon compounds may be used alone or in combination. Furthermore, the raw colloidal silica may be produced by a method other than the sol-gel method. In some embodiments, the average primary particle size of the abrasive is 5 nm or more, 6 nm or more, 7 nm or more, 8 nm or more, 9 nm or more, 10 nm or more, 11 nm or more, 12 nm or more, or 13 nm or more. In some embodiments, the average primary particle size of the abrasive is 33 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 19 nm or less, 17 nm or less, or 15 nm or less. The average primary particle size of the abrasive may be calculated from the specific surface area of the abrasive grains measured by the BET method using a Micromeritics Flow Sorb II 2300 and the density of the abrasive grains. In some embodiments, the average secondary particle size of the abrasive is 21 nm or more, 23 nm or more, 25 nm or more, 27 nm or more, 29 nm or more, 31 nm or more, or 33 nm or more. In some embodiments, the average secondary particle size of the abrasive is 60 nm or less, 50 nm or less, 45 nm or less, 40 nm or less, 38 nm or less, or 36 nm or less. The average secondary particle size of the abrasive may be calculated by dynamic light scattering using a Malvern Panalytical Zeta sizer.

[0016] In some embodiments, the CMP composition comprises about 0.01 wt.% to about 2 wt.% abrasive. In some embodiments, the CMP composition comprises less than 2 wt.% abrasive. In some embodiments, the CMP composition comprises less than 1 wt.%, less than 0.9 wt.%, less than 0.8 wt.%, less than 0.7 wt.%, less than 0.6 wt.%, less than 0.5 wt.%, less than 0.4 wt.%, less than 0.3 wt.%, or less than 0.2 wt.% abrasive. In some embodiments, the CMP composition comprises no more than 2 wt.%, no more than 1.5 wt.%, no more than 1.2 wt.%, no more than 1 wt.%, no more than 0.9 wt.%, no more than 0.8 wt.%, no more than 0.7 wt.%, no more than 0.6 wt.%, no more than 0.5 wt.%, no more than 0.4 wt.%, no more than 0.3 wt.%, or no more than 0.2 wt.% abrasive. In some embodiments, the CMP composition comprises at least 0.01 wt.%, at least 0.05 wt.%, at least 0.1 wt.%, at least 0.3 wt.%, at least 0.5 wt.%, or at least 0.7 wt.% abrasive.

[0017] SiN polishing speed enhancer Certain embodiments of the CMP composition of the present disclosure contain at least one SiN polishing rate enhancer. In some embodiments, the SiN polishing rate enhancer is selected from the group consisting of amino acids and heterocyclic carbon compounds. In some embodiments, the amino acid has an alkylene group with an amino group attached to the terminal end and a carboxyl group attached to the opposite terminal end. Non-limiting examples of suitable amino acids include β-alanine and 5-aminovaleric acid. In some embodiments, the alkylene group has 1 to 4, 1 to 3, or 1 or 2 carbon atoms. Non-limiting examples of suitable heterocyclic carbon compounds include heterocycles containing at least one ring nitrogen, such as azoles, triazoles, and pyrazines. Specific compounds include 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, guanazole, or aminopyrazine. Other compounds known to function as SiN polishing rate enhancers are also included in the present disclosure.

[0018] In some embodiments, the CMP composition comprises about 2 wt.% or less of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises about 1 wt.% or less of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises about 0.05 to about 0.5 wt.% of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises at least 0.05 wt.%, at least 0.06 wt.%, at least 0.07 wt.%, at least 0.08 wt.%, at least 0.09 wt.%, at least 0.1 wt.%, at least 0.2 wt.%, at least 0.3 wt.%, or at least 0.4 wt.% of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises at most 2 wt.%, at most 1.5 wt.%, at most 1.0 wt.%, at most 0.9 wt.%, less than 0.89 wt.%, at most 0.85 wt.%, at most 0.8 wt.%, at most 0.7 wt.%, at most 0.6 wt.%, or at most 0.5 wt.% of a SiN polishing rate enhancer. In some embodiments, the CMP composition contains about 0.1 wt %, about 0.2 wt %, about 0.3 wt %, about 0.4 wt %, about 0.5 wt %, about 0.6 wt %, about 0.7 wt %, about 0.8 wt %, about 0.9 wt %, or about 1 wt % of the SiN polishing rate enhancer. The numerical values in these embodiments can serve as the basis for upper or lower limits of the concentration of the SiN polishing rate enhancer, i.e., for appropriate adjustments. For example, the CMP composition contains about 0.2 wt % to about 0.9 wt %, about 0.3 wt % to about 0.8 wt %, or about 0.4 wt % to about 0.7 wt % of the SiN polishing rate enhancer.

[0019] In some embodiments, the abrasive is present in an amount greater than the SiN polishing rate enhancer. In some embodiments, the ratio (by weight) of abrasive to SiN polishing rate enhancer is within the range of about 1.5:1 to about 1.9:1. For example, in some embodiments, the ratio of abrasive to SiN polishing rate enhancer is about 1.5:1, 1.6:1, 1.7:1, 1.8:1, or 1.9:1. In these embodiments, the ratio of abrasive to SiN polishing rate enhancer can serve as the basis for upper or lower limits of the ratio of abrasive to SiN polishing rate enhancer, i.e., the basis for appropriate adjustments. For example, the ratio of abrasive to SiN polishing rate enhancer is about 1.5:1 to 1.7:1, about 1.5:1 to 1.8:1, or about 1.5:1 to 1.9:1.

[0020] Anionic surfactants Certain embodiments of the CMP composition of the present disclosure contain at least one anionic surfactant. In some embodiments, the anionic surfactant is a sulfonic acid surfactant. For example, ammonium alkyl polyoxyethylene ether sulfate is included in the present disclosure. Specific examples include ammonium alkyl polyoxyethylene ether sulfates having nonylphenyl, styrenated phenyl, isodecyl, or lauryl alkyl groups. Other compounds known to function as anionic surfactants in CMP compositions are included in the present disclosure. In some embodiments, the anionic surfactant is a sulfonic acid surfactant containing a benzene ring or a naphthalene ring. In some embodiments, the anionic surfactant is an alkylbenzenesulfonic acid or a salt thereof, or an alkylnaphthalenesulfonic acid or a salt thereof. In some embodiments, the alkyl group contained in the sulfonic acid surfactant has a linear or branched chain. Having a branched chain efficiently achieves the intended effects of the present invention. In some embodiments, the sulfonic acid surfactant contains two or more alkyl groups, or three or more alkyl groups. In some embodiments, the sulfonic acid surfactant contains four or fewer alkyl groups. In some embodiments, the salts of the above compounds are preferably sodium salts, ammonium salts, or the like.

[0021] In some embodiments, the CMP composition comprises about 0.1 wt% or less of a surfactant, for example, in some embodiments, the CMP composition comprises less than 0.01 wt%, less than 0.005 wt%, less than 0.002 wt%, less than 0.001 wt%, less than 0.0009 wt%, less than 0.0008 wt%, less than 0.0007 wt%, less than 0.0005 wt%, less than 0.0004 wt%, less than 0.0003 wt%, or less than 0.0002 wt% of an anionic surfactant. The CMP composition comprises 0.01 wt% or less, 0.005 wt% or less, 0.002 wt% or less, 0.001 wt% or less, 0.0009 wt% or less, 0.0008 wt% or less, 0.0007 wt% or less, 0.0005 wt% or less, 0.0004 wt% or less, 0.0003 wt% or less, or 0.0002 wt% or less of anionic surfactant. In some embodiments, the CMP composition comprises 0.00005 wt% or more, 0.0001 wt% or more, 0.0002 wt% or more, 0.0003 wt% or more, 0.0004 wt% or more, 0.0005 wt% or more, or 0.0006 wt% or more of surfactant.

[0022] Additional ingredients The liquid carrier for the CMP composition is not particularly limited. In some embodiments, the liquid carrier is water, such as deionized water. The liquid carrier may be, for example, an aqueous solution containing a suitable pH adjuster. In some embodiments, the liquid carrier may include one or more organic solvents, such as an alcohol compound, for example, an aliphatic alcohol containing 2 to 6 carbon atoms. In some embodiments, the liquid carrier may include one or more organic solvents, such as a glycol ether having 3 to 10 carbon atoms.

[0023] Examples of aliphatic alcohols having 2 to 6 carbon atoms include ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, pentanol, hexanol, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,4-butanetriol, 1,2,6-hexanetriol, erythritol, D-threitol, L-threitol Examples of glycol ethers having 3 to 10 carbon atoms include methyl glycol, methyl diglycol, methyl triglycol, isopropyl glycol, isopropyl diglycol, butyl glycol, butyl diglycol, butyl triglycol, isobutyl glycol, isobutyl diglycol, hexyl glycol, hexyl diglycol, 2-ethylhexyl glycol, 2-ethylhexyl diglycol, aryl glycol, phenyl glycol, phenyl diglycol, benzyl glycol, methyl propylene glycol, methyl propylene diglycol, methyl propylene triglycol, propyl propylene glycol, propyl propylene diglycol, butyl propylene glycol, butyl propylene diglycol, and phenyl propylene glycol. In some embodiments, the liquid carrier contains at least 90% by weight, at least 95% by weight, at least 98% by weight, at least 99% by weight, or at least 99.5% by weight of water.

[0024] In some embodiments, the pH of the CMP composition is about 3 to about 7. In some embodiments, the pH of the CMP composition is about 3 to about 6. For example, the pH can be about 4 to about 5. In some embodiments, the pH of the CMP composition is 3 or greater, 4 or greater, 4.5 or greater, or 4.8 or greater. In some embodiments, the pH of the CMP composition is less than 7, 6.5 or less, 6.2 or less, 6.0 or less, 5.8 or less, 5.5 or less, 5.3 or less, or 5 or less. Considering the intended effects of the present invention, it is preferable that the pH not exceed 5. In some embodiments, an appropriate pH adjuster and / or buffering agent can be included in the composition to adjust the pH. The pH of the CMP composition (liquid temperature: 25°C) can be confirmed using a pH meter (Horiba, Ltd., Model: LAQUA). For SiN bulk / buff slurries, one important performance metric is high SiN:TEOS removal rate selectivity to achieve minimal TEOS dishing. On the other hand, at pH ≥ 4, WO4 2- Dissolution of W into the SiN:TEOS structure (corrosion) can occur. If dissolution of the W film occurs during CMP, resulting in an increase in local electrical conductivity (EC) near adjacent TEOS structures on the patterned wafer, this can potentially affect SiN:TEOS removal rate selectivity and subsequent TEOS dishing. Thus, in some embodiments, novel CMP compositions can be provided that have high dielectric film material (e.g., SiN:TEOS) removal rate selectivity in the presence of metals such as W, especially at pH values above 4. Note that in the pH range below 4, a passive WO3 film can form. In some embodiments, the "sweet spot" for SiN:TEOS selectivity can be in the pH range of 4-5. Thus, in some embodiments, WO4 2- The selectivity of SiN to TEOS can also be improved within a pH range of 4-5, where there may be an increase in electrical conductivity due to formation. In some embodiments, the metal need not be W, but may be, for example, Mo.

[0025] In some embodiments, an acid is used as a pH adjuster. The acid used in connection with the present invention can be an organic or inorganic compound. Examples of acids include inorganic acids such as sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid; organic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, and carboxylic acids including lactic acid; and organic sulfuric acids including methanesulfonic acid, ethanesulfonic acid, and isethionic acid.

[0026] The content of the acid in the slurry is not particularly limited as long as the amount is such that the pH of the slurry falls within the above range.

[0027] In some embodiments, compositions according to the present disclosure may also contain biocides or other preservatives. Examples of preservatives and biocides that can be used in connection with the present invention include isothiazolinone preservatives such as 2-methyl-4-isothiazolin-3-one or 5-chloro-2-methyl-4-isothiazolin-3-one, parahydroxybenzoates, and phenoxyethanol. These preservatives and biocides may be used alone or in combination.

[0028] In certain embodiments, the electrical conductivity of the polishing slurry is less than 300 μS / cm. In certain embodiments, the electrical conductivity of the polishing slurry is greater than 100 μS / cm. The electrical conductivity of the polishing slurry can be evaluated using a benchtop electrical conductivity meter (manufactured by Horiba, Ltd., model number: DS-71). In some embodiments, the electrical conductivity of the polishing slurry is 400 μS / cm or less, 380 μS / cm or less, 360 μS / cm or less, 340 μS / cm or less, 320 μS / cm or less, 300 μS / cm or less, 280 μS / cm or less, 260 μS / cm or less, 240 μS / cm or less, 220 μS / cm or less, 200 μS / cm or less, 190 μS / cm or less, 180 μS / cm or less, or 170 μS / cm or less. In some embodiments, the electrical conductivity value of the polishing slurry is 80 μS / cm or more, 90 μS / cm or more, 100 μS / cm or more, 120 μS / cm or more, 140 μS / cm or more, 160 μS / cm or more, 170 μS / cm or more, 180 μS / cm or more, 190 μS / cm or more, or 200 μS / cm or more.

[0029] method In another aspect of the present disclosure, methods for CMP of a surface are provided herein. For example, a method for polishing a surface comprising W, TEOS / SiO2, and SiN, comprising supplying a polishing slurry of an embodiment of the present disclosure comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant. Particular embodiments include contacting the surface with a polishing pad, supplying a polishing slurry according to the present disclosure to the surface, and polishing the surface with the polishing slurry. In some embodiments, polishing comprises WO4 2- In some embodiments, the ratio of SiN removal to TEOS removal during polishing is greater than about 40:1. In some embodiments, the ratio of SiN removal to TEOS removal during polishing is greater than 42:1, greater than 44:1, greater than 46:1, or greater than 48:1. In some embodiments, the ratio of SiN removal to TEOS removal during polishing is less than 200:1, or less than 150:1.

[0030] In another aspect of the present disclosure, provided herein is a method for buffering metal oxide salts in a CMP slurry to increase robustness against TEOS removal, the method comprising polishing a surface comprising a metal (e.g., W, Mo) and TEOS by supplying a polishing slurry comprising an anionic modified colloidal silica abrasive and an anionic surfactant. Robustness is discussed below in connection with Table 4. Particular embodiments include contacting a surface with a polishing pad, supplying a polishing slurry according to the present disclosure to the surface, and polishing the surface with the polishing slurry. In some embodiments, the metal is W and the metal oxide salt is WO4. 2- anions. In some embodiments, the surface further comprises SiN, and the polishing slurry further comprises a SiN polishing rate enhancer. In some embodiments, the ratio of SiN removal to TEOS removal during polishing is greater than about 40:1. In some embodiments, greater than 42:1, greater than 44:1, greater than 46:1, or greater than 48:1. In some embodiments, the ratio of SiN removal to TEOS removal during polishing is less than 200:1, or less than 150:1. [Example]

[0031] Example 1: SiN:TEOS selectivity and W dissolution The SiN:TEOS selectivity and its effect on W dissolution for different pH regions are summarized in Table 1. The trends described in Table 1 apply to the interaction of each wafer type (SiN or TEOS) with particles with negative zeta potentials over the entire pH range (pH 2–pH 12).

[0032] [Table 1]

[0033] Table 2 shows the components and amounts of the slurries in this study, as well as the electrical conductivity (EC) values. A higher amount of β-alanine, which is a SiN removal rate enhancer and an important factor for slurry design, was used in the slurries to compensate for the lower abrasive loading for Slurry A.

[0034] [Table 2]

[0035] WO4 2- The increase in TEOS removal rate caused by the increase in local electrical conductivity from the formation is attributed to the contraction of the electrical double layer around the particles, i.e., higher local TEOS removal rate and potentially higher TEOS dishing on the patterned wafer.

[0036] WO4 2- The issue of poor robustness of TEOS removal rate to pH can be clearly seen for Slurry A in Figure 1, which shows that as greater amounts of K2WO4 are added to the slurry and electrical conductivity increases, the TEOS removal rate increases. Figure 1 shows the electrical conductivity of Slurry A, which was intentionally added with K2WO4 to achieve the amount shown on the X-axis of each plot, and the removal rate when used to polish TEOS under the polishing conditions listed in Table 4 on the Y-axis. The increased amount of K2WO4 resulted in higher WO4 removal rates for TEOS near W on patterned wafers at pH ≥ 4. 2- It is believed to simulate a chemical environment.

[0037] To evaluate the effect of W polishing on TEOS removal rate, an experimental polishing procedure was designed for W and TEOS blanket test wafers (blanket wafers) (see Table 3). The experimental procedure consisted of polishing TEOS lines near W lines on patterned wafers with WO4 2- The aim is to simulate a local increase in

[0038] Two blanket wafers were prepared, the first and second wafers. The pad was also treated with ex-situ conditioning. The first wafer was polished using the pad, followed by the second wafer. No conditioning treatment was performed between the first and second wafers. For example, no high-pressure rinse with deionized water was performed after the first wafer was polished, and no pad conditioning treatment was performed. The TEOS removal rate was then determined after the second polish.

[0039] More specifically, a TEOS blanket wafer was polished with Slurry A for 8 minutes using the ex-situ conditioned pad. Subsequently, another TEOS blanket wafer was polished with Slurry A for 4 minutes (Table 3, "a"), 8 min TEOS / 4 min TEOS), without pad cleaning or conditioning steps between each wafer polish.

[0040] Additionally, a W blanket wafer was polished for 8 minutes with Slurry A using the ex-situ conditioned pad. Subsequently, a TEOS blanket wafer was polished for 4 minutes with Slurry A (Table 3, "b"), 8 minutes W / 4 minutes TEOS). No pad cleaning or conditioning steps were performed between each wafer polish.

[0041] Table 3 briefly summarizes the procedures and objectives of the above experiment. It is important to note that in this experiment, no pad cleaning or conditioning process was performed between the polishing of each wafer. By not performing such cleaning or conditioning, the pad after polishing the first wafer contained materials derived from the first wafer. In other words, in the case of b) 8 min W / 4 min TEOS, materials derived from the first wafer included W (including dissolved forms of W), and by polishing a TEOS blanket wafer with a pad containing W (including dissolved forms of W), the effect of W (including dissolved forms of W) on TEOS could be evaluated.

[0042] [Table 3]

[0043] Figure 2 shows the effect of KWO on TEOS removal rate and electrical conductivity (EC) for additional specific CMP compositions. More specifically, Figure 2 plots the electrical conductivity of Slurry A and Slurry C, each intentionally added with KWO to achieve the amount of KWO shown on the X-axis of each plot, and the removal rate of TEOS when polished with these Slurries under the polishing conditions listed in Table 4 on the Y-axis.

[0044] As can be seen in Figure 2, the TEOS removal rate of the slurry has low robustness against W polishing (i.e., WO4 in (b)). 2- In other words, comparable TEOS removal rates (blanket wafer #2) for procedures a) and b) are expected to be higher than those for WO4 caused by W polishing. 2- This may indicate greater robustness against WO4 and potentially lower TEOS dishing on patterned wafers. That is, the comparable removal rates of 8 min TEOS / 4 min TEOS (ex-situ) and 8 min W / 4 min TEOS (ex-situ) are comparable. 2- This means that TEOS is highly robust against such conditions.

[0045] [Table 4]

[0046] Table 4 shows the TEOS removal rates using the experimental procedure shown in Table 3. For a SiN bulk / buffing slurry to be considered robust and effective, two requirements can be met:

[0047] 1) There is no significant increase in the TEOS removal rate with longer W polishing times, i.e., the absolute value of the difference between (a) and (b) is less than 0.9. Thus, in one embodiment, "enhancing robustness" means that the absolute value of the difference between (a) and (b) (also referred to as the robustness value) is less than 0.9, 0.8 or less, 0.7 or less, or 0.6 or less.

[0048] 2) SiN / TEOS selectivity >40.

[0049] In one embodiment of the present invention, there is provided a polishing slurry comprising an anionic modified colloidal silica abrasive and an anionic surfactant, having an electrical conductivity value of 100 μS / cm to 350 μS / cm and a robustness value of 0.9 or less.

[0050] As can be seen in Table 4, Slurries C and D satisfy both of the above requirements. There appears to be an ideal amount of β-alanine (or slurry electrical conductivity) to maintain the robustness of the TEOS removal rate for W polishing.

[0051] Table 5 shows the results of measuring the electrical conductivity and TEOS removal rate of each slurry, which was spiked with K2WO4 to the concentrations listed in Table 5, using slurries A and C in Table 2 as the base. The polishing conditions in Table 5 are as listed in Table 4.

[0052] As can be seen in Table 5, the increase in electrical conductivity and TEOS removal rate due to the K2WO4 spike is significantly lower in Slurry C compared to Slurry A. The 0.13 wt% K2WO4 spike (1000 ppm WO4 2- % KWO4 (equivalent to 1000 ppm WO4) results in a 13-fold increase in electrical conductivity in Slurry A, but only a 5.7-fold increase in Slurry C, thus allowing for a nearly two-fold reduction in electrical conductivity increase compared to Slurry A. As a result, the TEOS removal rate-enhancing Slurry C exhibits a 0.13 wt. % KWO4 (equivalent to 1000 ppm WO4) 2- ) is significantly lower (1.4 times) compared to the TEOS removal rate increase for slurry A (1.6 times).

[0053] Table 5 shows the improved WO4 content of Slurry C compared to Slurry A. 2- Helps demonstrate buffering capacity. 1000 ppm WO4 2- The ~5.7-fold increase in electrical conductivity after exposure to K2WO4 (Slurry C) allows for a significantly lower TEOS removal rate increase compared to the ~13-fold increase in electrical conductivity (Slurry A). This data suggests that significant differences in TEOS removal rate response should be expected within the range of 0.013–0.13 wt% K2WO4, suggesting a wider TEOS removal rate robustness window for Slurry C versus Slurry A.

[0054] [Table 5]

[0055] Another important parameter for the robustness of TEOS removal rate to W polishing can be the abrasive amount.

[0056] In some embodiments, the slurry may include a W corrosion inhibitor (eg, a nitrogen-containing W corrosion inhibitor such as benzotriazole).

[0057] equivalent The present technology should not be limited by the specific embodiments described in this application, which are intended to be merely illustrative of individual aspects of the technology. As will be apparent to those skilled in the art, many modifications and variations of the present technology can be made without departing from its spirit and scope. Functionally equivalent methods and apparatuses within the scope of the present technology, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to be within the scope of the present technology. It is understood that the present technology is not limited to particular methods, reagents, compounds, compositions, or biological systems, which can, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0058] Furthermore, when features or aspects of the present disclosure are described in terms of a Markush group, those skilled in the art will recognize that the present disclosure is also described thereby with respect to any individual member or subgroup of members of the Markush group.

[0059] As will be understood by those skilled in the art, for all purposes, particularly by the present specification, all ranges disclosed herein encompass all possible subranges and combinations of subranges. It can be readily recognized that any recited range fully describes and allows for equal ranges that can be divided into at least two, three, four, five, ten, etc. As a non-limiting example, each range described herein can be readily divided into a lower third, middle third, and upper third, etc. As will be understood by those skilled in the art, all terms, such as "up to," "at least," "greater than," and "less than," are inclusive of the recited numerical values and refer to ranges that can be subsequently divided into subranges as previously described. Finally, as will be understood by those skilled in the art, ranges include individual members. Thus, for example, a group having 1 to 3 items refers to groups having 1, 2, or 3 items. Similarly, a group having 1 to 5 items refers to groups having 1, 2, 3, 4, or 5 items, etc.

[0060] All numerical designations, including ranges, such as pH, temperature, time, concentration, amount, and molecular weight, are approximate and vary by (+) or (-), 10%, 1%, or 0.1%, as appropriate. Although not always explicitly stated, it should be understood that all numerical designations can be preceded by the term "about." As used herein, the term "about" is understood by those skilled in the art and will vary to some extent depending on the context in which it is used. If there is a use of the term that is not clear to those skilled in the art, given the context in which it is used, "about" will mean up to ±10% of the particular term. Although not always explicitly stated, it should be understood that the reagents described herein are merely exemplary, and that equivalents of such are known in the art.

[0061] All patents, patent applications, provisional applications and publications referenced or cited herein, including all figures and tables, are incorporated herein by reference in their entirety, to the extent not inconsistent with the explicit teachings of this specification.

[0062] Other embodiments are set forth in the following claims.

[0063] This application is based on U.S. Provisional Patent Application No. 63 / 083,461, filed September 25, 2020, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. W, TEOS / SiO ２ and a method of polishing a surface comprising SiN, comprising providing a polishing slurry comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant, the polishing slurry having an electrical conductivity value of 100 μS / cm to 350 μS / cm; the abrasive is anionic modified colloidal silica, The method wherein said polishing is carried out in the presence of WO 4 2− .

2. 10. The method of claim 1, wherein the abrasive is an anionic modified colloidal silica using sulfonate chemistry.

3. 3. The method of claim 2, wherein the anionic modified colloidal silica is treated with a sulfonate chemical.

4. The method according to any one of claims 1 to 3, wherein the polishing slurry has an electrical conductivity value of less than 300 µS / cm.

5. The method according to any one of claims 1 to 4, wherein the electrical conductivity value of the polishing slurry is greater than 100 μS / cm.

6. The method of any one of claims 1 to 5, wherein the polishing slurry has a pH of about 4 to about 5.

7. The method according to any one of claims 1 to 6, wherein the SiN polishing rate enhancer is selected from the group consisting of amino acids and heterocyclic carbon compounds.

8. The method according to any one of claims 1 to 7, wherein the anionic surfactant is selected from sulfonic acid surfactants.

9. The method of any one of claims 1 to 8, wherein the amount of SiN polishing rate enhancer is about 0.1 to about 0.8 wt%.

10. The method of any one of claims 1 to 9, wherein the amount of abrasive is about 0.8% by weight or less.

11. The method of any one of claims 1 to 10, wherein the ratio of SiN removal to TEOS removal during polishing is greater than about 40:1.

Images