TW202239891A - Cmp slurry composition and method of polishing tungsten pattern wafer - Google Patents

Abstract

A CMP slurry composition for polishing a tungsten pattern wafer and a method of polishing a tungsten pattern wafer using the same. The CMP composition includes a solvent; and silica satisfying relations 1 and 2. The definitions of relations 1 and 2 are as described in the specification. The invention secures improvement in polishing rate and flatness.

Description

Chemical mechanical polishing slurry composition and method for polishing tungsten patterned wafer

The invention relates to a CMP slurry composition for polishing tungsten pattern wafers and a method for polishing tungsten pattern wafers using the same.

This application claims the benefit of Korean Patent Application No. 10-2021-0042374 filed with the Korea Intellectual Property Office on March 31, 2021, the entire disclosure of which is incorporated herein by reference.

Chemical mechanical polishing (CMP) compositions and methods of polishing (or planarizing) the surface of a substrate are well known in the related art. Polishing compositions for polishing metal layers (eg, tungsten layers) on semiconductor substrates may include abrasive particles suspended in an aqueous solution and chemical accelerators such as oxidizing agents, catalysts, and the like.

The process of polishing the metal layer using the CMP composition includes: polishing the metal layer only; polishing the metal layer and the barrier layer; and polishing the metal layer, the barrier layer, and the oxide layer, using different polishing compositions according to the quality of the layers to polish each layer.

The object of the present invention is to provide a CMP slurry composition for polishing a tungsten patterned wafer, which does not need to use different polishing compositions for layers according to the quality of the layer during the process of polishing the tungsten patterned wafer.

Another object of the present invention is to provide a CMP slurry composition for polishing a tungsten patterned wafer, which ensures improvements in polishing rate and flatness.

Another object of the present invention is to provide a method for polishing a wafer with a tungsten pattern using a CMP slurry composition.

One aspect of the present invention relates to a CMP slurry composition for polishing a tungsten patterned wafer. The CMP slurry composition comprises: a solvent; and silicon dioxide satisfying the following relational formula 1 and relational formula 2:

70nm ≤ D ₁ ≤ 150nm, relation --- 1

45 ≤ {(D ₁ - D ₂ ) / D ₁ } × 100 ≤ 65, relation --- 2

where D ₁ represents the average particle size (unit: nanometer) of silicon dioxide measured by dynamic light scattering (dynamic light scattering; DLS), and D ₂ represents the image by transmission electron microscopy (TEM) The average particle size (unit: nanometer) of the silica measured analytically.

In one embodiment, D ₂ may be in the range of 25 nm to 80 nm.

In one embodiment, silica may be present in an amount of 0.001 weight percent (wt %) to 20 wt % in the CMP slurry composition.

In one embodiment, the CMP slurry composition may further include a quaternary ammonium salt having four substituents bonded to nitrogen atoms.

In one embodiment, the quaternary ammonium salt may be a quaternary alkyl ammonium salt having at least one _C4 to _C8 alkyl group bonded to the nitrogen atom.

In one embodiment, the cation of the quaternary ammonium salt may comprise tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, tetraheptylammonium, tetraoctylammonium, benzyltributylammonium, or combinations thereof.

In one embodiment, the quaternary ammonium salt may be present in an amount of 0.001% to 2% by weight in the CMP slurry composition.

In one embodiment, the CMP slurry composition may further include at least one of an oxidizing agent, a catalyst, and an organic acid.

In one embodiment, in the CMP slurry composition, the oxidizing agent may be present in an amount of 0.01% to 10% by weight, the catalyst may be present in an amount of 0.0001% to 10% by weight, and the organic acid may be present in an amount of The amount of % exists.

In one embodiment, the pH of the CMP slurry composition may be 1-6.

Another aspect of the invention relates to a method of polishing a tungsten patterned wafer. The method includes polishing a tungsten patterned wafer using the CMP slurry composition as set forth above.

The present invention provides a CMP slurry composition for polishing tungsten patterned wafers, which does not need to use different polishing compositions for layers according to the quality of the layers in the process of polishing tungsten patterned wafers and ensures the polishing rate and flatness. Improvement, and a method for polishing a tungsten patterned wafer using the CMP slurry composition.

Herein, unless the context clearly dictates otherwise, the singular forms "a" and "the" are intended to include the plural forms as well.

Furthermore, the terms "comprise", "include" and/or "have" when used in this specification designate the presence of stated features, steps, operations, elements and/or components, But it does not exclude the presence or addition of one or more other features, steps, operations, elements, components and/or groups.

Furthermore, unless expressly stated otherwise, numerical values relating to a certain component are interpreted as including tolerance ranges in the component interpretations.

As used herein to indicate a particular numerical range, the expression "a to b" is defined as "≥a and ≤b".

The present inventors completed the present invention based on the confirmation that a CMP slurry composition for polishing tungsten patterned wafers prepared using specific silica particles does not require different use of layers depending on the quality of the layers in the process of polishing tungsten patterned wafers. The polishing composition can ensure the improvement of polishing rate and flatness.

According to one aspect of the present invention, a CMP slurry composition for polishing a tungsten patterned wafer (hereinafter referred to as "CMP slurry composition") may include (A) a solvent and (B) silicon dioxide.

Hereinafter, components of the slurry composition will be described in detail. ( A ) Solvent

Solvents are used to reduce friction when polishing tungsten patterned wafers with abrasives.

In one embodiment, the solvent can be a polar solvent, a non-polar solvent, and combinations thereof. For example, the solvent may include water (eg, ultrapure water or deionized water), organic amines, organic alcohols, organic alcohol amines, organic ethers, organic ketones, and the like. In one embodiment, the solvent may be ultrapure water or deionized water, but is not limited thereto.

In one embodiment, the solvent may be included in the balance in the CMP slurry composition. ( B ) Silica

The silicon dioxide according to an embodiment of the present invention satisfies both the following relational expression 1 and relational expression 2, and is used to improve the flatness, while allowing relative to the tungsten layer and the insulating layer (such as , silicon oxide layer) rapid polishing. Silica can contain spherical or non-spherical particles and allows polishing of a polishing target with a single polishing composition when applied to a CMP slurry composition, independent of the polishing target at each step in the process of polishing a tungsten patterned wafer. Different polishing compositions are used depending on the quality of the polished layer.

70nm ≤ D ₁ ≤ 150nm, --- Relation 1

45 ≤ {(D ₁ - D ₂ ) / D ₁ } × 100 ≤ 65, --- Relation 2

where D1 represents the average particle size _of silicon dioxide (unit: nm) measured by DLS (unit: nm), and D2 represents the average particle size of silicon _dioxide (unit: nm) measured by TEM image analysis Meter).

In one embodiment, D ₁ may be in the range of 70 nm to 150 nm, such as 80 nm to 120 nm, specifically 90 nm to 110 nm. When D ₁ is not within this range, there may be problems regarding flatness of the tungsten pattern wafer and deterioration of the polishing rate.

In one embodiment, {(D ₁ −D ₂ )/D ₁ }×100 may be in the range of 45 to 65, such as 50 to 64, specifically 55 to 63. When silicon dioxide does not satisfy Relational Expression 2, there may be problems regarding flatness and polishing rate deterioration of the tungsten patterned wafer.

In one embodiment, D ₂ may be in the range of 25 nm to 80 nm, such as 30 nm to 60 nm, specifically 35 nm to 50 nm. Within this range, silicon dioxide can ensure good effects in improving the polishing rate and/or planarity, but is not limited thereto.

In one embodiment, silicon dioxide can be produced by controlling the production conditions in a typical step of producing silicon dioxide or by appropriately combining at least two kinds of commercially available silicon dioxide to satisfy both relational expression 1 and relational expression 2. Silicon.

In one embodiment, silica may be present in the CMP slurry composition in an amount of 0.001% to 20% by weight, such as 0.01% to 17% by weight, specifically 0.05% to 15% by weight. Within this range, silicon dioxide can ensure good effects in improving the polishing rate and/or planarity, but is not limited thereto.

According to an embodiment, the CMP slurry composition may further include at least one selected from (C) quaternary ammonium salt, (D) oxidizing agent, (E) catalyst, and (F) organic acid. ( C ) Quaternary ammonium salt

The quaternary ammonium salt has four substituents bonded to the nitrogen atom and is used to improve the dispersion and storage stability of the CMP slurry composition with silica.

In one embodiment, the substituent may comprise a C ₁ to C ₈ alkyl group or a C ₆ to C ₁₀ aryl group, such as a C ₄ to C ₈ alkyl group or a C ₆ to C ₁₀ aryl group.

In one embodiment, the quaternary ammonium salt may be a quaternary alkyl ammonium salt, and may comprise a cation represented by (R ₁ )(R ₂ )(R ₃ )(R ₄ )N ⁺ (wherein each of R ₁ to R ₄ independently C ₁ to C ₈ alkyl or C ₆ to C ₁₀ aryl, for example C ₄ to C ₈ alkyl or C ₆ to C ₁₀ aryl, at least one of R ₁ to R ₄ is C ₁ to C ₈ alkyl or C ₄ to C ₈ alkyl) and anions (for example, F ^- , Cl ^- , Br ^- , I ^- , OH ^- , CO ₃ ^2- , PO ₄ ^3- , SO ₄ ^2- etc.).

In one embodiment, the cation of the quaternary ammonium salt may comprise tetramethylammonium, tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, tetraheptylammonium, tetraoctylammonium, benzyltributylammonium, or combination. For example, the cation may include tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, tetraheptylammonium, tetraoctylammonium, benzyltributylammonium, or a combination thereof, but is not limited thereto.

In one embodiment, the quaternary ammonium salt may be present in the CMP slurry composition in an amount of 0.001% to 2% by weight, such as 0.005% to 1% by weight, specifically 0.01% to 0.5% by weight. Within this range, the CMP slurry composition may exhibit good dispersion and good storage stability, but is not limited thereto. ( D ) Oxidizing agent

The oxidizing agent is used to facilitate polishing of the tungsten patterned wafer by oxidizing the tungsten patterned wafer.

In one embodiment, the oxidizing agent may comprise at least one selected from the group consisting of inorganic peroxide compounds, organic peroxide compounds, bromic acid or salts thereof, nitric acid or salts thereof, chloric acid or salts thereof, chromic acid Or its salts, iodic acid or its salts, iron or its salts, copper or its salts, rare earth metal oxides, transition metal oxides, potassium dichromate and mixtures thereof. Here, a per compound refers to a compound containing at least one peroxy group (-O-O-) or an element in the highest oxidation state. In one embodiment, the oxidizing agent may comprise a per compound (eg, hydrogen peroxide, potassium periodide, calcium persulfate, potassium ferricyanide, etc.). In another embodiment, the oxidizing agent may be hydrogen peroxide, but not limited thereto.

In one embodiment, the oxidizing agent may be present in the CMP slurry composition at 0.01% to 10% by weight, such as 0.05% to 8% by weight, specifically 0.1% to 6% by weight, more specifically 0.2% by weight present in amounts of up to 5% by weight. Within this range, the oxidizing agent is used to improve the polishing rate of the tungsten patterned wafer, but is not limited thereto. ( E ) Catalyst

Catalysts are used to improve the polishing rate of tungsten patterned wafers.

In one embodiment, the catalyst may include, for example, iron ion compounds, complex compounds of iron ions, and hydrates thereof.

In one embodiment, the iron ion compound may comprise, for example, an iron trivalent cation-containing compound. The compound containing an iron trivalent cation may be selected from any compound having an iron trivalent cation that exists as a free cation in aqueous solution. For example, the compound containing iron trivalent cations may include at least one of ferric chloride (FeCl ₃ ), ferric nitrate (Fe(NO ₃ ) ₃ ), and ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), but not limited to this.

In one embodiment, the complex compound of iron ions may comprise, for example, a complex compound containing iron trivalent cations. The iron trivalent cation-containing complex compound may include a compound formed by reacting an iron trivalent cation with an organic or inorganic compound having at least one functional group such as carboxylic acid, phosphoric acid, sulfuric acid, amino acid, and amine in an aqueous solution. Examples of organic or inorganic compounds may include citrate, ammonium citrate, p-toluene sulfonic acid (pTSA), 1,3-propylenediaminetetraacetic acid (PDTA) , ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA) and ethylenediamine-N,N'-disuccinate Acid (ethylenediamine-N,N'-disuccinic acid; EDDS), but not limited thereto. Examples of the compound containing iron trivalent cations may include iron citrate, iron ammonium citrate, Fe(III)-pTSA, Fe(III)-PDTA, and Fe(III)-EDTA, but are not limited thereto.

In one embodiment, the catalyst (for example, at least one of an iron ion compound, an iron ion complex compound, and a hydrate thereof) in the CMP slurry composition may be 0.0001% by weight to 10% by weight, such as 0.0005% by weight to 8% by weight, specifically 0.001% to 5% by weight, more specifically 0.002% to 1% by weight. Within this range, the CMP slurry composition can improve the polishing rate of the tungsten metal layer, but is not limited thereto. ( F ) Organic acids

Organic acids are used to stabilize the pH of the CMP slurry composition.

In one embodiment, the organic acid may comprise a carboxylic acid (such as malonic acid, maleic acid, malic acid, etc.) or an amino acid (such as glycine, isoleucine, leucine, phenylalanine, methionine , threonine, tryptophan, valine, alanine, arginine, cysteine, glutamic acid, histidine, proline, serine, tyrosine and lysine, etc.) .

In one embodiment, the organic acid may be present in the CMP slurry composition at 0.001% to 10% by weight, such as 0.002% to 5% by weight, specifically 0.005% to 1% by weight, more specifically 0.01% by weight % to 0.5% by weight. Within this range, the organic acid can stabilize the pH of the CMP slurry composition, but is not limited thereto.

According to one embodiment, the pH of the CMP slurry composition may be 1 to 6, such as 1.5 to 5.5, specifically 1.5 to 3.5. Within this range, the CMP slurry composition allows easy oxidation of the tungsten pattern wafer to prevent a decrease in polishing rate, but is not limited thereto.

In one embodiment, the CMP slurry composition may further include a pH regulator to maintain a proper pH value.

In one embodiment, the pH adjuster may comprise an inorganic acid (e.g., at least one of nitric acid, phosphoric acid, hydrochloric acid, and sulfuric acid) and an organic acid (e.g., an organic acid with a pKa of about 6 or less, such as acetic acid and/or phthalates). The pH adjuster may contain at least one alkali such as ammonia solution, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, and potassium carbonate.

According to one embodiment, the CMP slurry composition may further include typical additives, such as biocides, surfactants, dispersants, modifiers, surfactants, and the like. In the CMP slurry composition, the additive may be present in an amount of 0.001% to 5% by weight, such as 0.005% to 1% by weight, specifically 0.01% to 0.5% by weight. Within this range, the additive can achieve its effect without affecting the polishing rate, but is not limited thereto.

According to another aspect of the present invention, a method of polishing a tungsten patterned wafer is provided. The polishing method comprises polishing a tungsten patterned wafer using the CMP slurry composition according to the present invention.

Next, the present invention will be described in more detail with reference to examples. It should be noted, however, that these examples are provided for illustration only and should not be construed as limiting the invention in any way. Example Example 1 to Example 6 and Comparative Example 1 to Comparative Example 4

Based on the total weight of the CMP slurry composition, by mixing 5% by weight of D ₁ , D ₂ and {(D ₁ - D ₂ )/D ₁ } × 100 as listed in Table 1 and Table 2 Silicon dioxide, 0.1% by weight of tetrabutyl ammonium hydroxide (TBAH), benzyltributylammonium chloride (BzTBACl) or tetramethyl ammonium hydroxide (TMAH) As a quaternary ammonium salt, 0.05% by weight of Fe(III)-FNA as a catalyst, 0.1% by weight of malonic acid as an organic acid, and the rest of deionized water as a solvent were used to prepare a CMP slurry composition. The pH of the CMP slurry composition was adjusted to 2.7 using a pH adjuster, and 2% by weight of hydrogen peroxide was added as an oxidizing agent to the slurry composition immediately before polishing evaluation of the tungsten patterned wafer. Characteristic evaluation

(1) The average particle size of silica measured by DLS (D ₁ , unit: nanometer): Zetasizer Nano ZS (Malvern Panalytical Co., Ltd) was used to prepare The average particle size of silica was measured on a sample with 1% by weight of particles in ultrapure water.

(2) Average particle diameter of silicon dioxide (D ₂ , unit: nm) measured by TEM image analysis: The sample was prepared to have 0.1% by weight of particles and was measured using a TEM (TF30, Thermo Fisher (FEI company )) Take pictures at 19.5k magnification. Next, the major diameters of 500 silica particles were measured and averaged.

(3) Polishing evaluation: Polishing evaluation was performed on the CMP slurry compositions prepared in Examples and Comparative Examples under the following polishing conditions. The results are shown in Table 1. [Polishing Evaluation Conditions] (i) Polishing machine: Reflexion 300mm (Applied Materials Co., Ltd. (AMAT Co., Ltd.)) (ii) Polishing conditions - Polishing pad: IC1010/SubaIV Stacked (Rodel Co., Ltd.) - Head speed: 101 rpm - Platen speed: 100 rpm - Pressure: 3.5 psi - Retaining ring pressure: 8 psi - Slurry flow rate: 200ml/min - Polishing time: 60 seconds (iii) Polishing target: Tungsten patterned wafer (MIT 854, 300mm) (iv) Analysis method - Polishing rate (unit: Angstrom/minute (Å/min)): The polishing rate of the tungsten metal layer was calculated based on the resistance corresponding to the film thickness difference before and after polishing in the evaluation under the above polishing conditions. The polishing rate of the insulating layer (oxide layer) was calculated based on the resistance corresponding to the film thickness difference before and after polishing under the above polishing conditions as measured using a reflectometer. - Erosion (unit: Angstrom (Å)): After polishing the wafer with the CMP slurry composition, the thickness of the wafer at 0.3 µm was measured by using an atomic force microscope (Uvx-Gen3, Bruker Co., Ltd.). × 0.3 µm in the contour of the hole area to calculate erosion. - Edge Over-Erosion (EOE, in Angstroms): After polishing the wafer with a CMP slurry composition, the crystallinity was measured by using an atomic force microscope (Uvx-Gen3, Bruker Ltd.) in the 0.18 μm × 0.18 μm line and space region. The contour of the circle to calculate the EOE.

Table 1 example 1 2 3 4 5 6 D1 98 94 116 98 98 98 D2 40 51 42 40 40 40 {(D1 - D2) / D1} × 100 59 46 64 59 59 59 Quaternary ammonium TBAH TBAH TBAH BYZGR - TMAH Tungsten Polishing Rate (Angstroms/min) 5,500 5,700 5,300 5,400 5,600 5,350 Oxide layer polishing rate (Angstroms/min) 850 870 820 830 780 840 Erosion (Angstroms) 20 twenty four 18 twenty one 20 28 EOE (angstroms) 0 0 0 0 0 0

Table 2 comparative example 1 2 3 4 D1 61 180 85 135 D2 25 95 48 42 {(D1 - D2) / D1} × 100 59 47 44 69 Quaternary ammonium TBAH TBAH TBAH TBAH Tungsten Polishing Rate (Angstroms/min) 3,530 3,400 4,800 5,000 Oxide layer polishing rate (Angstroms/min) 410 800 570 640 Erosion (Angstroms) 42 31 47 39 EOE (angstroms) 10 25 8 10

As can be seen from the above results, the CMP slurry composition for polishing tungsten patterned wafers according to the present invention does not need to use different polishing compositions for layers according to the quality of the layers in the process of polishing tungsten patterned wafers, ensuring relative Good polishing rate and improved planarity of tungsten and oxide layers.

On the contrary, it can be seen that the slurry composition (Comparative Example 1) prepared using silica having an average particle diameter D1 measured by DLS smaller than that of the silica according to the present invention (Comparative Example 1) suffered relative to the tungsten layer and the Deterioration of the polishing rate of the oxide layer with high erosion and EOE indicative of planarity deterioration and using a slurry prepared with a silica having an average particle diameter D1 measured by DLS greater than that of the silica according to the invention The material composition (Comparative Example 2) suffers from deterioration in polishing rate relative to the tungsten layer and has high erosion and EOE indicative of planarity deterioration. In addition, it can be seen that the slurry composition prepared using silica having a value of {(D ₁ − D ₂ )/D ₁ }×100 lower than that of the silica according to the present invention (Comparative Example 3 ) suffers from a deterioration in the polishing rate relative to the tungsten layer and the oxide layer and has high erosion and EOE indicative of planarity deterioration, and using a value of {(D ₁ - D ₂ )/D ₁ } × 100 greater than that according to the present invention The silica-made slurry composition (Comparative Example 4) for the stated value of silica suffers from degradation in polishing rate relative to the oxide layer and has high erosion and EOE indicative of planarity degradation.

Although a few embodiments have been described herein, it will be understood by those skilled in the art that various modifications, changes and alterations can be made without departing from the spirit and scope of the invention. Accordingly, it should be understood that these examples are provided for illustration only and should not be construed as limiting the invention in any way. The scope of the invention should be defined by the appended claims rather than by the foregoing description, and claims and their equivalents are intended to cover such modifications and the like as would fall within the scope of the invention.

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Claims (11)

A chemical mechanical polishing slurry composition for polishing a tungsten patterned wafer, comprising: a solvent; and silicon dioxide satisfying the following relational formula 1 and relational formula 2: 70 nanometers ≤ D ₁ ≤ 150 nanometers, --- Relational expression 1 45 ≤ {(D ₁ - D ₂ ) / D ₁ } × 100 ≤ 65, --- Relational expression 2 where D ₁ represents the average particle diameter of the silica measured by dynamic light scattering, D ₁ The unit of is nanometer, and D ₂ represents the average particle diameter of the silicon dioxide measured by transmission electron microscopy image analysis, and the unit of D ₂ is nanometer. The chemical mechanical polishing slurry composition as claimed in claim ₁ , wherein D2 is in the range of 25 nm to 80 nm. The chemical mechanical polishing slurry composition according to claim 1, wherein in the chemical mechanical polishing slurry composition, the silicon dioxide is present in an amount of 0.001 wt % to 20 wt %. The chemical mechanical polishing slurry composition as claimed in claim 1, further comprising: a quaternary ammonium salt having four substituents bonded to nitrogen atoms. The chemical mechanical polishing slurry composition according to claim 4, wherein the quaternary ammonium salt comprises a quaternary alkyl ammonium salt having at least one C4 to C8 alkyl group bonded to a nitrogen atom. The chemical mechanical polishing slurry composition as claimed in item 4, wherein the cation of the quaternary ammonium salt includes tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, tetraheptylammonium, tetraoctylammonium, benzyl Tributylammonium or combinations thereof. The chemical mechanical polishing slurry composition as claimed in claim 4, wherein in the chemical mechanical polishing slurry composition, the quaternary ammonium salt is present in an amount of 0.001% by weight to 2% by weight. The chemical mechanical polishing slurry composition according to claim 1 further includes: at least one of an oxidizing agent, a catalyst and an organic acid. The chemical mechanical polishing slurry composition according to claim 7, wherein in the chemical mechanical polishing slurry composition, the oxidizing agent is present in an amount of 0.01% by weight to 10% by weight, and the catalyst is present in an amount of 0.0001% by weight % to 10% by weight, and the organic acid is present in an amount of 0.001% to 10% by weight. The chemical mechanical polishing slurry composition as claimed in claim 1, wherein the pH of the chemical mechanical polishing slurry composition is 1-6. A method for polishing a wafer with a tungsten pattern, comprising: using the chemical mechanical polishing slurry composition according to any one of claims 1 to 10 to polish the wafer with a tungsten pattern.