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 generally relates to compositions and methods for polishing surfaces including metal and dielectric film materials.

Background Art

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

[0003] Furthermore, tungsten (W) can be part of a patterned wafer.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This specification provides novel compositions and novel methods for polishing surfaces including metal and dielectric film materials.

Means for Solving the Problems

[0005] Certain aspects of the present disclosure include a method of polishing a surface comprising W, TEOS / SiO2, and SiN, the method comprising supplying 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 electrical conductivity value of the polishing slurry is less than 300 μS / cm. In some embodiments, the electrical conductivity value of the polishing slurry is 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 type surfactants. In some embodiments, the amount of the SiN polishing rate enhancer is about 0.05 to about 0.5 wt%. In some embodiments, the amount of the abrasive is 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, the polishing is performed in the presence of WO4 2- . Here, TEOS means tetraethyl orthosilicate, and TEOS / SiO2 indicates that silicon oxide (SiO2) is a silicon oxide film derived from tetraethyl orthosilicate.

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

[0007] Certain embodiments of the present disclosure are 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 the abrasive to the SiN polishing rate enhancer is in the range of from about 1.5:1 to about 1.9:1. In some embodiments, the CMP composition has a pH of from about 4 to about 5. In some embodiments, Si The N polishing rate enhancer is β-alanine.

[0008] Certain embodiments of the present disclosure are methods of polishing a surface comprising W, TEOS / SiO2, and SiN, comprising supplying a polishing slurry comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant, the electrical conductivity value of which is from 100 μS / cm to 350 μS / cm.

[0009] Certain embodiments of the present disclosure are methods of buffering metal oxide salts in a CMP slurry to enhance robustness against TEOS removal, comprising polishing a surface comprising metal and TEOS by supplying a polishing slurry comprising an anionic modified colloidal silica abrasive and an anionic surfactant, the electrical conductivity value of which is from 100 μS / cm to 350 μS / cm. Certain embodiments of the present disclosure are 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, the ratio of the abrasive to the SiN polishing rate enhancer is in the range of from about 1.5:1 to about 1.9:1, and the electrical conductivity value is from 100 μS / cm to 350 μS / cm.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

[0011] Provided herein are CMP compositions and methods for polishing surfaces including metal and dielectric film materials. As used herein, the terms “chemical mechanical polishing” or “planarization” refer to the process of planarizing (polishing) a surface by a combination of surface chemical reaction and mechanical abrasion. In some embodiments, the chemical reaction is initiated by supplying to the surface a composition (referred to interchangeably as a “polishing (CMP) slurry,” “CMP composition,” “polishing composition,” “slurry composition,” or simply “slurry”) capable of reacting with the surface material, whereby the surface material is converted into a product 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 compositions disclosed herein can include, consist essentially of, or consist of one or more of the following components. Here, “consist essentially of” means that components not intended to be added to the composition (components other than those described below) may be included, for example, up to 0.001 wt% as an upper limit in the CMP polishing composition.

[0013] Abrasive The CMP compositions of the present disclosure contain at least one abrasive. The abrasive in the CMP composition provides, or enhances, a 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 anionic modified colloidal silica. In some embodiments, the anionic modified colloidal silica is modified using a sulfonate chemical. Thus, some embodiments are that the CMP composition comprises anionic modified colloidal silica containing anionic groups (e.g., sulfonic acid groups) bonded to the surface of the particles of the starting colloidal silica. In some embodiments, the 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 with sulfonic acid immobilized on the 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 material colloidal silica can be, for example, colloidal silica produced by the sol-gel method. The production of the raw material colloidal silica by the sol-gel method can be carried out using conventionally known techniques. Specifically, a hydrolyzable silicon compound (for example, alkoxysilane or its derivative) is used as a raw material, and by performing hydrolysis and condensation reactions, the raw material colloidal silica can be obtained. The silicon compound may be used alone or in combination of two or more. Furthermore, the raw material colloidal silica may be produced by a method other than the sol-gel method. In some embodiments, the average primary particle diameter 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 diameter 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 diameter of the abrasive may be calculated from the specific surface area of the abrasive grains by the BET method measured using "Flow SorbII 2300" manufactured by Micromeritics and the density of the abrasive grains. In some embodiments, the average secondary particle diameter 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 diameter 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 diameter of the abrasive may be calculated by the dynamic light scattering method measured using "Zeta sizer" manufactured by Malvern Panalytical Ltd.

[0016] In some embodiments, the CMP composition comprises from about 0.01 wt% to about 2 wt% of an abrasive. In some embodiments, the CMP composition comprises less than 2 wt% of an 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% of an abrasive. In some embodiments, the CMP composition comprises 2 wt% or less, 1.5 wt% or less, 1.2 wt% or less, 1 wt% or less, 0.9 wt% or less, 0.8 wt% or less, 0.7 wt% or less, 0.6 wt% or less, 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, or 0.2 wt% or less of an abrasive. In some embodiments, the CMP composition comprises 0.01 wt% or more, 0.05 wt% or more, 0.1 wt% or more, 0.3 wt% or more, 0.5 wt% or more, or 0.7 wt% or more of an abrasive.

[0017] SiN Polishing Rate Enhancer Certain embodiments of the CMP compositions 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 amino group bonded to the end of an alkylene group and a carboxyl group bonded to the opposite 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 azole, triazole, and pyrazine. 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 up to about 2 wt% of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises up to about 1 wt% of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises from about 0.05 to about 0.5 wt% of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises 0.05 wt% or more, 0.06 wt% or more, 0.07 wt% or more, 0.08 wt% or more, 0.09 wt% or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, or 0.4 wt% or more of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises up to 2 wt%, up to 1.5 wt%, up to 1.0 wt%, up to 0.9 wt%, less than 0.89 wt%, up to 0.85 wt%, up to 0.8 wt%, up to 0.7 wt%, up to 0.6 wt%, or up to 0.5 wt% of a SiN polishing rate enhancer. In some embodiments, the CMP composition comprises 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 a SiN polishing rate enhancer. The numerical values in these embodiments can be used as the basis for the upper or lower limits of the concentration of the SiN polishing rate enhancer. That is, they can be used as the basis for appropriate corrections. For example, the CMP composition comprises from about 0.2 wt% to about 0.9 wt%, from about 0.3 wt% to about 0.8 wt%, or from about 0.4 wt% to about 0.7 wt% of a 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 the abrasive to the SiN polishing rate enhancer is in the range of about 1.5:1 to about 1.9:1. For example, in some embodiments, the ratio of the abrasive to the SiN polishing rate enhancer is about 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1. The ratio of the abrasive to the SiN polishing rate enhancer in such embodiments can be the basis for the upper or lower limit of the ratio of the abrasive to the SiN polishing rate enhancer. That is, it can be the basis for appropriate correction. For example, the ratio of the abrasive to the SiN polishing rate enhancer is about 1.5:1 to 1.7:1, about 1.5:1 to 1.8:1, about 1.5:1 to 1.9:1.

[0020] Anionic surfactant 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 type surfactant. For example, ammonium alkyl polyoxyethylene ether sulfate is included in the present disclosure. Specific examples include ammonium alkyl polyoxyethylene ether sulfates having a nonylphenyl, styrenated phenyl, isodecyl or lauryl alkyl group. Other compounds known to function as anionic surfactants in the CMP composition are included in the present disclosure. In some embodiments, the anionic surfactant is a sulfonic acid type surfactant containing a benzene ring or a naphthalene ring. In some embodiments, the anionic surfactant is an alkylbenzene sulfonic acid or its salt, or an alkylnaphthalene sulfonic acid or its salt. In some embodiments, the alkyl group contained in the sulfonic acid type surfactant has a straight chain or a branched chain. Having a branched chain efficiently achieves the intended effect of the present invention. In some embodiments, the number of alkyl groups contained in the sulfonic acid type surfactant is two or more or three or more. In some embodiments, the number of alkyl groups contained in the sulfonic acid type surfactant is four or less. In some embodiments, the above salts are preferably sodium salts, ammonium salts, etc.

[0021] In some embodiments, the CMP composition comprises a surfactant in an amount of about 0.1 wt% or less. . For example, in some embodiments, the CMP composition comprises an anionic surfactant in an amount of 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%. The CMP composition comprises an anionic surfactant in an amount of 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. In some embodiments, the CMP composition comprises a surfactant in an amount of 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.

[0022] Additional Components The liquid carrier of 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 can include one or more organic solvents, such as alcohol compounds, for example, aliphatic alcohols containing 2 to 6 carbon atoms. In some embodiments, the liquid carrier can include one or more organic solvents, such as glycol ethers 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, D-arabinitol, L-arabinitol, ribitol, xylitol, mannitol, and sorbitol. 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, in the liquid carrier, water is 90 wt% or more, 95 wt% or more, 98 wt% or more, 99 wt% or more, or 99.5 wt% or more.

[0024] In some embodiments, the pH of the CMP composition is a value from about 3 to about 7. In some embodiments, the pH of the CMP composition is a value from about 3 to about 6. For example, the pH can be from about 4 to about 5. In some embodiments, the pH of the CMP composition is 3 or more, 4 or more, 4.5 or more, or 4.8 or more. 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 does not exceed 5. In some embodiments, a suitable pH adjuster and / or buffer can be included in the composition to adjust the pH. The pH of the CMP composition (liquid temperature: 25 °C) can be confirmed by a pH meter (model number: LAQUA, manufactured by Horiba, Ltd.). In the case of SiN bulk / buffer slurry, one important performance measurement criterion is the high SiN:TEOS removal rate selectivity to obtain minimal tetraethyl orthosilicate (T EOS) dishing. On the other hand, at pH ≥ 4, there may be dissolution of W into WO4 2- (corrosion). 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, it can potentially affect the SiN:TEOS removal rate selectivity and subsequent TEOS dishing. Thus, in some embodiments, even when the pH of the CMP composition is particularly 4 or more, a novel CMP composition can be provided that has a high dielectric film material (e.g., SiN:TEOS) removal rate selectivity in the presence of a metal such as W. Note that in the region where the pH is less than 4, a passive WO3 film can be formed. In some embodiments, the "sweet spot" for SiN:TEOS selectivity can be in the range of pH 4 - 5. Thus, in some embodiments, even within pH 4 - 5 where there may be an increase in electrical conductivity due to WO4 2- formation, the selectivity of SiN to TEOS can be improved. In some embodiments, the metal can be Mo instead of W, for example.

[0025] In some embodiments, an acid is used as the 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, phosphoric acid, and organic acids such as carboxylic acids including 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, lactic acid, and organic sulfates 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 slurry has the above pH range.

[0027] In some embodiments, the composition according to the present disclosure may also include a biocide or other preservative. Examples of preservatives and biocides that can be used in connection with the present invention include isothiazolin-based preservatives such as 2-methyl-4-isothiazolin-3-one or 5-chloro-2-methyl-4-isothiazolin-3-one, paraoxybenzoic acid esters, and phenoxyethanol. These preservatives and biocides may be used alone or in combination of two or more.

[0028] In certain embodiments, the electrical conductivity value of the polishing slurry is less than 300 μS / cm. In certain embodiments, the electrical conductivity value of the polishing slurry is greater than 100 μS / cm. The electrical conductivity of the polishing slurry can be evaluated by a desktop electrical conductivity meter (manufactured by Horiba, Ltd., model number: DS-71). In some embodiments, the electrical conductivity value 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, a method for CMP of a surface is provided herein. For example, a method of polishing a surface comprising W, TEOS / SiO2, and SiN, the polishing slurry of embodiments of the present disclosure comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant A method comprising supplying. Certain embodiments can include contacting the surface with a polishing pad, supplying the polishing slurry according to the present disclosure to the surface, and polishing the surface with the polishing slurry. In some embodiments, the polishing is performed in the presence of 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, a method for buffering metal oxide salts in a CMP slurry to enhance robustness against TEOS removal, including polishing a surface containing metal (e.g., W, Mo) and TEOS by supplying a polishing slurry containing an anionic modified colloidal silica abrasive and an anionic surfactant, is provided herein. Note that the robustness will be described in relation to Table 4 below. Certain embodiments can include contacting the surface with a polishing pad, supplying the 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- contains anions. In some embodiments, the surface further includes SiN and the polishing slurry further includes 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, it is greater than 42:1, greater than 44:1, greater than 46:1, 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.

Examples

[0031] Example 1: SiN:TEOS Selectivity and W Dissolution Table 1 summarizes the effects on SiN:TEOS selectivity and W dissolution for different pH ranges. The trends described in Table 1 apply to the interaction between each wafer type (SiN or TEOS) and particles having a negative zeta potential over the entire pH range (pH 2 to 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. More amount of β-alanine, which is a SiN removal rate improver and an important element for slurry design, was used in the slurry to compensate for the lower abrasive amount for Slurry A.

[0034]

Table 2

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

[0036] WO4 2- The problem of low robustness of the TEOS removal rate for WO4 can be clearly seen for Slurry A in Figure 1, showing that as more amount of K2WO4 is added to the slurry and the electrical conductivity increases, the TEOS removal rate increases. Figure 1 shows that K2WO4 was intentionally added to Slurry A such that the amount of K2WO4 is shown on the X-axis of each plot, their electrical conductivities were measured, and the removal rates when TEOS was polished under the polishing conditions described in Table 4 using them are shown on the Y-axis. The increased amount of K2WO4 is thought to simulate the high WO4 2- chemical environment near W on the patterned wafer at pH ≧ 4.

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

[0038] Two blanket wafers were prepared as the first wafer and the second wafer. Also, ex-situ conditioning was performed to process the pad. After polishing the first wafer using the pad, the second wafer was polished. Note that no conditioning process was performed between the polishing of the first wafer and the polishing of the second wafer. For example, no high-pressure rinse with deionized water was performed after polishing the first wafer, nor was the pad conditioning process performed. By doing so, the TEOS removal rate was determined after the second polishing.

[0039] More specifically, the TEOS blanket wafer was polished with slurry A for 8 minutes using the pad that had undergone ex-situ conditioning. Subsequently, another TEOS blanket wafer was polished with slurry A for 4 minutes (「a)」8 minutes TEOS / 4 minutes TEOS in Table 3). At this time, no pad cleaning or conditioning process was performed between the polishing of each wafer.

[0040] Also, the W blanket wafer was polished with slurry A for 8 minutes using the pad that had undergone ex-situ conditioning. Subsequently, the TEOS blanket wafer was polished with slurry A for 4 minutes (「b)」8 minutes W / 4 minutes TEOS in Table 3). At this time, no pad cleaning or conditioning process was performed between the polishing of each wafer.

[0041] Table 3 summarizes the procedures and purposes of the above experiments briefly. The key point in this experiment is that no pad cleaning or conditioning process was performed between the polishing of each wafer. By not performing such cleaning and conditioning, the pad after polishing the first wafer contains substances derived from the first wafer. That is, for 「b)」8 minutes W / 4 minutes TEOS, the substances derived from the first wafer include W (including the dissolved form of W), etc. By polishing the TEOS blanket wafer using the pad containing W (including the dissolved form of W), etc., the influence of W (including the dissolved form of W), etc. on TEOS can be evaluated.

[0042]

Table 3

[0043] Figure 2 shows the effect of K2WO4 on the TEOS removal rate and the electrical conductivity (EC) for a more specific CMP composition. More specifically, in Figure 2, K2WO4 was intentionally added to slurry A and slurry C, respectively, so as to be the amount of K2WO4 shown on the X-axis of each plot, and their electrical conductivities were measured. Also, the removal rate when polishing TEOS under the polishing conditions described in Table 4 using them is shown on the Y-axis.

[0044] As can be seen in Figure 2, when the TEOS removal rate of the slurry has low robustness against W polishing (i.e., is more strongly affected by b) of WO4), it is expected to show a higher TEOS removal rate (blanket wafer #2) than a). In other words, equivalent TEOS removal rates (blanket wafer #2) for procedures a) and b) can indicate higher robustness against WO4 caused by W polishing and potentially lower TEOS dishing on the patterned wafer. That is, the fact that the removal rates of 8-minute TEOS / 4-minute TEOS (ex-situ) and 8-minute W / 4-minute TEOS (ex-situ) are equivalent means that the robustness of TEOS against WO4 is high. 2- by), it is expected to show a higher TEOS removal rate (blanket wafer #2) than a). In other words, equivalent TEOS removal rates (blanket wafer #2) for procedures a) and b) can indicate higher robustness against WO4 caused by W polishing and potentially lower TEOS dishing on the patterned wafer. That is, the fact that the removal rates of 8-minute TEOS / 4-minute TEOS (ex-situ) and 8-minute W / 4-minute TEOS (ex-situ) are equivalent means that the robustness of TEOS against WO4 is high. 2- on the patterned wafer. That is, the fact that the removal rates of 8-minute TEOS / 4-minute TEOS (ex-situ) and 8-minute W / 4-minute TEOS (ex-situ) are equivalent means that the robustness of TEOS against WO4 is high. 2- is high.

[0045]

Table 4

[0046] Table 4 shows the TEOS removal rate using the experimental procedure shown in Table 3. In order to consider the SiN bulk / buff slurry to be robust (having robustness) and efficient, the following two requirements can be met.

[0047] 1) There is no significant increase in the TEOS removal rate with a longer W polishing time. That is, the absolute value of the difference between (a) and (b) is less than 0.9. Therefore, 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, a polishing slurry is provided that includes an anionic-modified colloidal silica polishing agent and an anionic surfactant, has an electrical conductivity value of 100 μS / cm to 350 μS / cm, and a robustness value of 0.9 or less.

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

[0051] Table 5 shows the results including measuring the electrical conductivity and the TEOS removal rate after intentionally adding (spiking) K2WO4 to the concentrations described in Table 5 based on Slurry A and Slurry C in Table 2, respectively. The polishing conditions in Table 5 are as described in Table 4.

[0052] As also 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. A 0.13 wt% K2WO4 spike (equivalent to 1000 ppm WO4 2- results in a 13-fold increase in electrical conductivity in Slurry A, but only a 5.7-fold increase in Slurry C. Therefore, Slurry C allows for a decrease of almost twice the increase in electrical conductivity compared to Slurry A. As a result, the increase in the TEOS removal rate for Slurry C is 0.13 wt% K2WO4 (1000 ppm WO4 2-) is significantly lower (1.4 times) compared to the increased TEOS removal rate of slurry A (1.6 times).

[0053] Table 5 shows the improved WO4 of slurry C compared to slurry A 2- which helps to demonstrate the buffering capacity. An increase in electrical conductivity of 5.7 times or less (slurry C) after exposure to 1000 ppm of WO4 2- enables a significantly lower increase in the TEOS removal rate compared to an increase in electrical conductivity of 13 times or more (slurry A). This data suggests that a significant difference in the TEOS removal rate response should be expected within the range of 0.013 - 0.13 wt% of K2WO4, indicating a broader robust window of TEOS removal rate for slurry C compared to slurry A.

[0054]

Table 5

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

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

[0057] Equivalents The present technology should not be limited by the specific embodiments described in this application, which are merely intended as examples of the individual aspects of the present technology. As will be apparent to those skilled in the art, many modifications and variations of this present technology can be made without departing from its spirit and scope. In addition to those listed herein, functionally equivalent methods and apparatuses within the scope of the present technology will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the present technology. It should be understood that the present technology is not limited to a particular method, reagent, compound, composition or biological system and, of course, can vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0058] Furthermore, if a feature or aspect of the present disclosure is described by a Markush group, those skilled in the art will recognize that the present disclosure is also described 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, and in particular by the description in the specification, all ranges disclosed herein include all possible sub-ranges and combinations of those sub-ranges. It can be readily recognized that any recited range can be fully described and enabled by equal sub-ranges that are divided, for example, into at least halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range described herein can be readily divided into, for example, lower third, middle third, and upper third. As will be understood by those skilled in the art, for example, all language such as "up to", "at least", "greater than", "less than", etc. includes the recited numerical value and refers to a range that can be subsequently divided into sub-ranges as described above. 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 a group having 1, 2, or 3 items. Similarly, a group having 1 to 5 items refers to a group having 1, 2, 3, 4, or 5 items, etc.

[0060] All numerical representations that include ranges, for example, pH, temperature, time, concentration, amount, and molecular weight, are approximate and may vary by 10%, 1%, or 0.1% (+) or (-) as appropriate. It should be understood that although not necessarily explicitly stated, the term "about" can be prefixed to all numerical representations. As used herein, the term "about" is understood by those skilled in the art and varies to some extent depending on the context in which it is used. In cases where the use of the term is not clear to those skilled in the art, considering the context in which it is used, "about" would mean up to ±10% of the particular term. It should be understood that although not necessarily explicitly stated, the reagents described herein are merely illustrative and that equivalents of such are known in the art.

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

[0062] Other embodiments are described in the following claims.

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

Claims

1. W, TEOS / SiO ２ A method of polishing a surface containing SiN, comprising supplying a polishing slurry containing an abrasive, a SiN polishing rate improver, and an anionic surfactant, and having an electrical conductivity value of 100 μS / cm to 350 μS / cm.

2. The method according to claim 1, wherein the abrasive is an anionic modified colloidal silica using a sulfonate chemical substance.

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

4. The method according to any one of claims 1 to 3, wherein the electrical conductivity value of the polishing slurry is 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 according to 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 type surfactants.

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

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

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

1.

12. The polishing is carried out in the presence of WO ４ ２－ The method according to any one of claims 1 to 11.

13. A method for buffering metal oxide salts in a CMP slurry to enhance robustness against TEOS removal, comprising supplying a polishing slurry comprising an anionic modified colloidal silica abrasive and an anionic surfactant and having an electrical conductivity value of 100 μS / cm to 350 μS / cm, and polishing a surface containing metal and TEOS.

14. The method according to claim 13, wherein the electrical conductivity value of the polishing slurry is less than 300 μS / cm.

15. wherein the metal is W and the metal oxide salt is WO ４ ２－ The method according to any one of claims 13 or 14, comprising an anion.

16. The method according to any one of claims 13 to 15, wherein the surface further contains SiN and the polishing slurry further contains a SiN polishing rate enhancer.

17. The method according to any one of claims 13 to 16, wherein the polishing slurry has a pH of about 4 to about 5.

18. A CMP composition comprising an anionic modified colloidal silica abrasive, a SiN polishing rate enhancer, and an anionic surfactant, The anionic modified colloidal silica abrasive is present in an amount of 1 wt% or less, the ratio of the abrasive to the SiN polishing rate improver is in the range of about 1.5 to 1 to about 1.9 to 1, and the electrical conductivity value is 100 μS / cm to 350 μS / cm, a CMP composition.

19. The CMP composition according to claim 18, wherein the CMP composition has a pH of about 4 to about 5.

20. The CMP composition according to claim 18 or 19, wherein the SiN polishing rate improver is β-alanine.

21. 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.

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