TW201435072A - Polishing solution for metal and polishing method - Google Patents

Abstract

Provided is a polishing solution for metal intended for polishing at least part of a metal, which includes: (A) an amino acid, (B) a 1-hydroxybenzotriazole, (C) a compound with a benzotriazole skeleton (except 1-hydroxybenzotriazole), (D) a polymer having at least one structural unit of among: structural unit derived from (meta)acrylic acid, structural unit derived from (meta)acrylate, structural unit derived from (meta)acrylamide, and structural unit derived from amino(meta)acrylamide. Weight average molecular mass of compound (D) is 10000 or more, total mass ratio of total content of compound (B) and compound (C) to the total content of (D) is 0.15 to 3.00 and pH is 3.0 to 6.0.

Description

Metal polishing liquid and grinding method

The present invention relates to a polishing liquid for metal and a polishing method. More particularly, the present invention relates to a metal polishing liquid and a polishing method for use in chemical mechanical polishing of metal (hereinafter referred to as "CMP").

In recent years, a new microfabrication technology has been developed along with the high integration and high performance of a semiconductor integrated circuit (hereinafter referred to as "LSI"). Chemical mechanical polishing (CMP) is one of such microfabrication techniques, and is an interlayer insulating material frequently used in a large scale integrated circuit (LSI) manufacturing process, particularly in a multilayer wiring forming step. The technique of planarization, metal plug formation, and embedded wiring formation (for example, refer to Patent Document 1 below).

Recently, in order to improve the performance of LSI, it has been attempted to use copper-based metals such as copper, copper alloy, copper oxide, and copper alloy oxide as wiring materials. However, it is difficult for the copper-based metal to perform the microfabrication by the dry etching method which is frequently used in the formation of the conventional aluminum alloy wiring. Therefore, a so-called damascene method is mainly employed in which a copper-based metal is deposited on an insulating material on which a concave portion (groove portion) and a convex portion are formed, and a copper-based metal is embedded in the concave portion, and then the convex portion is removed by CMP. Stacked copper metal (copper gold other than recess) In order to form an embedded wiring (for example, refer to Patent Document 2 below).

The polishing liquid for metal used in CMP contains abrasive grains, an oxidizing agent, a metal dissolving agent, a metal resist, and the like as necessary. It is generally considered that in the CMP using a polishing liquid containing an oxidizing agent, the oxide layer is formed by oxidizing the metal surface by the oxidizing agent, and the etching of the oxide layer is the basic mechanism. In such polishing, since the oxide layer on the metal surface of the concave portion does not contact the polishing cloth, it is not affected by the grinding effect. Therefore, as the CMP progresses, the metal on the convex portion is removed, and the surface of the substrate is flattened.

As a method of increasing the polishing rate of CMP (hereinafter referred to as "CMP rate"), it is effective to add a metal dissolving agent to the polishing liquid. On the other hand, the metal of the recess is etched, which has the effect of affecting the planarization effect. In order to prevent this, a metal resist is sometimes added to the polishing liquid. As such a polishing liquid, it is important to maintain the balance between the metal dissolving agent and the metal resist, and it is desirable that the etching layer of the metal surface of the concave portion is not excessively etched, the ground metal can be efficiently dissolved, and the CMP speed is fast.

At present, in addition to metal dissolving agents and metal resists, studies have been conducted to add various substances to the polishing liquid as additives, by which relatively high CMP rates (400 to 500 nm/min) may be obtained, and lower. Etching speed (for example, refer to Patent Documents 3 and 4 below).

[Previous Technical Literature] (Patent Literature)

Patent Document 1: US Patent No. 4944836

Patent Document 2: Japanese Patent Laid-Open No. 2-278822

Patent Document 3: Japanese Laid-Open Patent Publication No. 2010-538457

Patent Document 4: Japanese Laid-Open Patent Publication No. 2009-514219

On the other hand, LSI is further improving its performance, and in particular, wiring is becoming finer, which is a trend of semiconductor components in recent years. With the miniaturization of the wiring, a higher degree of planarization is required in the process of forming a plurality of wirings. In the grinding step of the metal, it is particularly required to sufficiently reduce the etching rate. Moreover, in recent years, from the viewpoint of reliability of a semiconductor element, it is required to further reduce damage (polishing damage) on the surface of the substrate generated during polishing.

However, in the prior art, it is not sufficient to simultaneously achieve a higher CMP speed and a lower etching speed, and it is insufficient to obtain, for example, a highly reliable embedded pattern. Moreover, in the conventional technique including a metal resist, polishing damage may occur in the middle of polishing, and grinding damage may be reduced.

As described above, the CMP speed, the etching rate, and the polishing damage of the metal are closely related to each other, and it has been difficult to achieve such required characteristics at the same time.

The present invention has been made in view of the above problems, and an object thereof is to provide a polishing liquid for metal and a polishing method using the polishing liquid for metal, which can achieve a high CMP rate and a low etching rate and suppress polishing damage. The production.

The metal polishing liquid of the present invention is for grinding at least a part of a metal, and comprises: (A) an amino acid; (B) 1-hydroxybenzotriazole; (C) a compound having a benzotriazole skeleton (but , (except 1-hydroxybenzotriazole); and, (D) a polymer having at least one selected from the group consisting of a structural unit of acrylic acid, a structural unit derived from (meth)acrylate, a structural unit derived from (meth)acrylamide, and a structural unit derived from an amino (meth)acrylamide; wherein The weight average molecular weight of the component D) is 10,000 or more, and the mass ratio of the content of the component (B) and the content of the component (C) to the content of the component (D) (the total of the components (B) and (C)/ The component (D) is 0.15 to 3.00, and the pH is 3.0 to 6.0.

According to the polishing liquid for metal of the present invention, a higher CMP rate and a lower etching rate can be achieved. Moreover, according to the polishing liquid for metal of the present invention, the occurrence of polishing damage can be suppressed. In the conventional polishing liquid for metal, it is considered that the organometallic compound formed by the following is one of the main causes of polishing damage: a material obtained by dissolving a material such as a metal removed by polishing in water, and Metal resist. On the other hand, it is considered that the polishing liquid for metal according to the present invention can suppress the formation of an organometallic compound, thereby suppressing the occurrence of polishing damage. Thereby, according to the polishing liquid for metal of the present invention, the flatness of the surface to be polished can be improved, and an embedded pattern of a metal having high reliability can be formed.

Preferably, the component (A) comprises glycine.

The pH of the polishing liquid for metal of the present invention may also be 4.5 to 5.0.

The polishing liquid for metal of the present invention may further contain at least one selected from the group consisting of hydrogen peroxide, potassium periodate, and ozone water.

The polishing liquid for metal of the present invention may further contain abrasive grains.

The ground metal may also comprise at least one selected from the group consisting of copper, copper alloys, copper oxides, and copper alloy oxides. That is, according to the present invention, there is provided an application of a polishing liquid for metal for grinding a package A metal containing at least one selected from the group consisting of copper, a copper alloy, an oxide of copper, and an oxide of a copper alloy.

In the polishing method of the present invention, at least a part of the metal is polished using the above-described polishing liquid for metal. In the polishing method of the present invention, by using the above-mentioned polishing liquid for metal, when the metal is polished, a high CMP rate and a low etching rate can be achieved and the occurrence of polishing damage can be suppressed.

According to the present invention, a higher CMP speed and a lower etching rate can be achieved and the occurrence of grinding damage can be suppressed. Thereby, the flatness of the surface to be polished can be improved, and an embedded pattern of a metal having high reliability can be formed.

1‧‧‧ bottom

1a‧‧‧Substrate

1b‧‧‧Interlayer insulation

2‧‧‧Baffle materials

3‧‧‧Conductive substances

10, 20, 30‧‧‧ base

Fig. 1 is a schematic cross-sectional view showing an embodiment of a polishing method.

Hereinafter, a polishing liquid for a metal according to an embodiment of the present invention and a polishing method using the polishing liquid for the metal will be described in detail.

[definition]

In the present specification, "abrasive substance A" and "grinding of substance A" are defined as at least a part of the substance A removed by grinding. The "higher CMP speed" is defined as the speed at which the substance to be ground is removed by CMP (for example, the thickness reduction per unit time) is faster.

Further, "(meth)acrylic acid" means acrylic acid and methacrylic acid corresponding thereto. "(Meth) acrylamide" means acrylamide and its corresponding methacrylamide.

Moreover, the "copper-based metal" means a metal containing a copper atom, and specifically refers to an oxide of copper, a copper alloy, copper, or a copper alloy.

Further, the numerical range indicated by "~" indicates a range including the numerical values before and after the "~" as the minimum value and the maximum value, respectively.

Further, in the present specification, when a plurality of substances corresponding to the respective components are present in the composition, the content of each component in the composition means the total of the plurality of substances present in the composition unless otherwise specified. the amount.

[Metal slurry]

The polishing liquid for metal of this embodiment is used to polish at least a part of the metal. The polishing liquid for metal of the present embodiment is used, for example, in the step of manufacturing a semiconductor element, and is used for CMP of a copper-based metal.

The polishing liquid for metal of the present embodiment contains: (A) an amino acid; (B) 1-hydroxybenzotriazole; (C) a compound having a benzotriazole skeleton (except for 1-hydroxybenzotriazole) And (D) a polymer having at least one structural unit derived from (meth)acrylic acid, a structural unit derived from (meth)acrylic acid, and derived from (group) selected from the group consisting of a structural unit of methyl acrylamide and a structural unit derived from an amino (meth) acrylamide. The weight average molecular weight of the component (D) is 10,000 or more. The mass ratio of the content of the component (B) and the content of the component (C) to the content of the component (D) (the total of the component (B) and the component (C)/component (D)) is 0.15 to 3.00. The polishing liquid for metal of the present embodiment has a pH of 3.0 to 6.0. In addition, the components (A) to (D) and other constituent components in the polishing liquid for metal may be used alone or in combination of two or more.

(metal dissolver)

In the polishing liquid for metal of the present embodiment, as a metal dissolving agent, There is (A) amino acid. Examples of the amino acid include glycine, α-alanine, β-alanine (alias: 3-aminopropionic acid), 2-aminobutyric acid, n-proline, lysine, and leucine Acid, norleucine, isoleucine, diisoleucine, phenylalanine, valine, creatinine, ornithine, lysine, taurine, serine, threonine , bethreic acid, homoserine, tyrosine, 3,5-diiodotyrosine, β-(3,4-dihydroxyphenyl)alanine, thyroxine, 4-hydroxyproline, half Cystamine, methionine, ethionine, lanthione, cystathionine, cystine, cysteic acid, aspartic acid, glutamic acid, carboxymethyl cysteamine Acid, 4-aminobutyric acid, aspartame, glutamine, azoserine, arginine, concanavalin, citrulline, δ-hydroxylysine, creatine, canine Amino acid, histidine, 1-methylhistamine, 3-methylhistamine, ergothioneine, tryptophan, actinomycin C1, bee venom, angiotensin I, Angiotensin II and anti-pain.

From the viewpoint of achieving a higher CMP rate and a lower etching rate to a higher degree at the same time, it is preferred that the (A) amino acid contains glycine. In order to further increase the CMP rate, the (A) amino acid may also contain an amino acid other than glycine. As the amino acid other than glycine, a low molecular weight amino acid is preferred. Specifically, an amino acid having a molecular weight of 200 or less is preferable, and an amino acid having a molecular weight of 150 or less is more preferable. Further, as the (A) amino acid, a primary amino acid having a first amine group (-NH ₂ ) is preferred. Examples of such an amino acid include α-alanine, β-alanine, and 4-aminobutyric acid.

The content of the (A) amino acid is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and still more preferably 0.1 part by mass or more, based on 100 parts by mass of the polishing liquid. Especially preferred 0.5 parts by mass or more, particularly preferably 0.8 parts by mass or more. The content of the (A) amino acid is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, based on 100 parts by mass of the polishing liquid. It is particularly preferably 2 parts by mass or less, and particularly preferably 1.5 parts by mass or less. From the above viewpoints, the content of the (A) amino acid is preferably in the range of 0.001 to 10 parts by mass.

In order to further increase the CMP rate, the polishing liquid for metal of the present embodiment may contain a metal dissolving agent other than the amino acid. Examples of the metal-soluble agent include inorganic acid components such as inorganic acids and inorganic acid salts (inorganic salts); and organic acid components such as organic acids, organic acid esters, and organic acid salts (organic salts).

Examples of the inorganic acid component include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and chromic acid, and salts of such inorganic acids (for example, ammonium sulfate or ammonium nitrate).

Examples of the organic acid component include formic acid, acetic acid, propionic acid, butyric acid, shikimic acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, and 4 -methylvaleric acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, glyoxylic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, Organic acids such as succinic acid, glutaric acid, gluconic acid, adipic acid, pimelic acid, maleic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, and citric acid; esters of such organic acids ( For example, ethyl acetate or amyl acetate); and a salt of the above organic acid (for example, ammonium acetate or the like).

When a metal dissolving agent other than an amino acid is contained, the content of the amino acid is the same as the content of the metal dissolving agent other than the amino acid (metal dissolving agent) The total amount is preferably in the range of 0.001 to 10 parts by mass.

(metal resist)

In the polishing liquid for metal of the present embodiment, two or more compounds having a benzotriazole skeleton are contained as a metal resist, and one of the compounds is 1-hydroxybenzotriazole. That is, the polishing liquid for metal of the present embodiment contains (B) 1-hydroxybenzotriazole and (C) a compound having a benzotriazole skeleton (except for 1-hydroxybenzotriazole). Further, the "compound having a benzotriazole skeleton" includes a compound containing a benzotriazole skeleton in a molecule such as naphthotriazole.

By using the components (B) and (C) in combination, a higher CMP rate and a lower etching rate can be achieved and the occurrence of polishing damage can be suppressed. It is generally believed that this is mainly because the (C) component exhibits a higher CMP rate and a lower etching rate, and the component (B) exhibits a reduction in the grinding damage.

Examples of the component (C) include benzotriazole, a benzotriazole derivative, naphthotriazole, and a naphthotriazole derivative.

As the benzotriazole derivative, 1-(2,3-dihydroxypropyl)-benzotriazole and 2,3-dicarboxy-propylbenzotriazole (2,3-dicarboxy-propyl benzotriazole) are exemplified. ), 4-hydroxybenzotriazole, 4-carboxy(-1H-)benzotriazole, 4-carboxy(-1H-)benzotriazole methyl ester, 4-carboxy(-1H-)benzotriazole Butyl ester, 4-carboxy(-1H-)benzotriazolyl, 5-hexylbenzotriazole, [1,2,3-benzotriazol-1-methyl][1,2,4- Triazolyl-1-methyl][2-ethylhexyl]amine and methylbenzotriazole (alias: 5-methyl(-1H-)benzotriazole) and the like.

Examples of the naphthotriazole derivative include 1H-naphtho[2,3-d]triazole 1-amine, 1-amino-1H-naphtho[1,2-d]triazole, and 2-amine. yl-2H-naphtho[1,2-d] Oxazole, 3H-naphtho[1,2-d]triazole and 4,9-dihydro-1H-naphtho[2,3-d]triazole.

Among the foregoing compounds, benzotriazole, methylbenzotriazole and naphthotriazole are preferred from the viewpoint of achieving a higher CMP rate and a lower etching rate to a higher degree. Preferably, it is a benzotriazole or a methylbenzotriazole, and further preferably a methylbenzotriazole.

The total amount of the component (B) and the content of the component (C) is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, further more than 100 parts by mass of the polishing liquid. It is preferably 0.01 parts by mass or more, particularly preferably 0.02 parts by mass or more, and particularly preferably 0.025 parts by mass or more. The total of the content of the component (B) and the content of the component (C) is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, based on 100 parts by mass of the polishing liquid. Further, it is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, particularly preferably 0.1 part by mass or less, very preferably 0.05 part by mass or less, and still more preferably 0.04 part by mass or less.

The content of the component (B) is preferably 0.0005 parts by mass or more, more preferably 0.001 parts by mass or more, and still more preferably 0.003 parts by mass or more, especially from 100 parts by mass of the polishing liquid. It is preferably 0.005 parts by mass or less. The content of the component (B) is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, based on 100 parts by mass of the polishing liquid. It is particularly preferably 0.5 parts by mass or less, particularly preferably 0.1 parts by mass or less, very preferably 0.05 parts by mass or less, and still more preferably 0.02 parts by mass or less.

In addition to the components (B) and (C), the metal for use in the present embodiment The grinding fluid may comprise a known metal resist. As the metal resist, a heterocyclic compound is known, and specific examples thereof include a compound having a triazole skeleton (except for the components (B) and (C) described above), a compound having a pyrimidine skeleton, and an imidazole. A compound of a porphyrin skeleton, a compound having an anthracene skeleton, a compound having a thiazole skeleton, a compound having a pyrazole skeleton, and the like.

When a metal resist other than the component (B) and the component (C) is used, the content thereof is preferably 0.001 to 0.5 parts by mass based on 100 parts by mass of the polishing liquid. On the other hand, from the viewpoint of easily achieving a high CMP rate and a low etching rate and suppressing the occurrence of polishing damage, it is preferred that the metal resist contains the component (B) and the component (C).

(polymer)

In the polishing liquid for metal of the present embodiment, as the component (D), a polymer having at least one structural unit derived from (meth)acrylic acid and a source selected from the group consisting of the following is contained. A structural unit derived from a (meth) acrylate, a structural unit derived from (meth) acrylamide, and a structural unit derived from an amino (meth) acrylamide.

Such a polymer can be obtained by polymerizing at least one selected from the group consisting of (meth)acrylic acid and a salt thereof, (meth)acrylamide, and an amine group (methyl group). ) acrylamide. Examples of the (meth) acrylate include an ammonium salt and a sodium salt.

Examples of the component (D) include poly(meth)acrylic acid, poly(meth)acrylamide, amine poly(meth)acrylamide, poly(meth)acrylate ammonium, and poly(methyl). Sodium acrylate and the like. The (D) component is preferably poly(methyl) from the viewpoint of achieving a higher CMP rate and a lower etching rate at the same time to a higher degree. Acrylic acid and poly(meth)acrylic acid salt, more preferably polyacrylic acid and polyacrylic acid salt, further preferably polyacrylic acid.

The component (D) may have a structural unit derived from a monomer component other than the following (for example, an alkyl (meth)acrylate such as methyl acrylate or methyl methacrylate): (meth)acrylic acid, (A) Acrylate, (meth) acrylamide and amino (meth) acrylamide. The component (D) may have a side chain such as a mercapto group, a hydroxyl group, a urea group, a carboxyl group, a methyl group or a sulfo group. The component (D) may also be a copolymer of two or more monomer components. The polymerization form of the component (D) is not particularly limited, and examples thereof include block polymerization and random polymerization.

The weight average molecular weight of the component (D) is 10 × 10 ³ or more from the viewpoint of exhibiting a high CMP rate. The weight average molecular weight of the component (D) is preferably 20 × 10 ³ or more, and more preferably 40 × 10 ³ or more from the viewpoint of easily exhibiting a high CMP rate. The upper limit of the weight average molecular weight of the component (D) is not particularly limited, but is preferably 5,000 × 10 ³ or less, more preferably 1,000 × 10 ³ or less, still more preferably 500 × 10 from the viewpoint of excellent solubility. ³ or less. The weight average molecular weight of the component (D) can be measured by gel permeation chromatography using a calibration curve of standard polystyrene under the following conditions.

(condition)

Standard polystyrene: Standard polystyrene manufactured by Tosoh Corporation (molecular weight: 190000, 17900, 9100, 2980, 578, 474, 370, 266)

Instrument (detector): Differential refractometer manufactured by Hitachi, Ltd. (Hitachi, Ltd.), L-3300 liquid chromatograph

Pump: manufactured by Hitachi, Ltd., liquid chromatography with L-7100 Instrument

Data Processing: D-2520 GPC Integrator, manufactured by Hitachi, Ltd.

Pipe column: manufactured by Showa Denko K.K., Shodex Asahipak GF-710HQ, inner diameter 7.6mm × 300mm

Effervescent solution: 50 mM Na ₂ HPO ₄ aqueous solution / acetonitrile = 90/10 (v / v)

Flow rate: 0.6mL/min (min=min)

Sample: a sample obtained by filtering a solution having the same composition as the extract to a resin concentration of 2% and then filtering it with a 0.45 μm PTFE filter

Injection volume: 0.4μL

Standard material for calibration: manufactured by Polymer Laboratories, narrow molecular weight sodium polyacrylate

The content of the component (D) is preferably 0.005 parts by mass or more, and more preferably 0.01 parts by mass or more, based on 100 parts by mass of the polishing liquid, from the viewpoint of the effect of the use of the metal resist in which the etching is suppressed. Further, it is preferably 0.02 parts by mass or more, and particularly preferably 0.03 parts by mass or more. The content of the component (D) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 1 part by mass, based on 100 parts by mass of the polishing liquid. In the following, it is particularly preferably 0.5 parts by mass or less, particularly preferably 0.2 parts by mass or less, and very preferably 0.1 parts by mass or less.

From the viewpoint of a higher CMP speed, the mass ratio of the content of the component (B) and the content of the component (C) to the content of the component (D) ((the content of the component (B) and (C)) Total content of ingredients) / (D) content) It is 0.15 or more. The quality is preferably 0.20 or more, more preferably 0.30 or more, still more preferably 0.40 or more from the viewpoint of easily exhibiting a high CMP speed. The mass ratio is 3.00 or less from the viewpoint of suppressing the etching rate and exhibiting a sufficient CMP speed. The quality is preferably 1.50 or less, more preferably 1.00 or less, and still more preferably 0.90 or less from the viewpoint of easily suppressing the etching rate and easily expressing a sufficient CMP speed.

When the metal is polished using the polishing liquid for metal of the present embodiment, the (C) component which is more hydrophobic is adsorbed on the metal to be polished, and then the (B) component and the (D) component which are more hydrophilic are adsorbed. On the metal being polished. It is generally believed that a reaction layer is formed on the metal to be polished. Then, the polishing is performed by the friction of the reaction layer with the polishing cloth. When the mass ratio of the component (B) and the component (C) to the component (D) is within the above range, when the reaction layer is formed, the hydrophobic structure of the component (C) will face one side in contact with the polishing cloth. Therefore, it is considered that the friction with the polishing cloth is improved, and the function of increasing the CMP speed is obtained. At the same time, the hydrophilic structure of the component (B) makes the surface of the metal to be polished hydrophilic, and it is easier to supply the slurry component to the vicinity of the metal to be polished. Since the surface polishing liquid component is in a large amount, it is considered that the metal to be polished is polished at a high CMP rate.

The polishing liquid for metal of the present embodiment has a pH of 3.0 to 6.0. When the pH of the polishing liquid for metal is 3.0 or more, etching is suppressed. The pH of the polishing liquid for metal is preferably 3.5 or more, more preferably 4.0 or more, and still more preferably 4.5 or more from the viewpoint of more easily suppressing etching. If the pH of the polishing liquid for metal is 6.0 or less, a sufficient CMP rate will be obtained. The pH of the metal slurry is preferably from the viewpoint of easily obtaining a sufficient CMP speed. It is 5.6 or less, more preferably 5.3 or less, further preferably 5.0 or less. When the pH of the polishing liquid for metal of the present embodiment is 4.5 to 5.0, the etching rate is suppressed and the CMP rate is particularly increased. The pH is defined as the pH at a liquid temperature of 25 °C.

The polishing liquid for metal of the present embodiment can also be adjusted to a pH value using an acid or a base as a pH adjuster. Examples of the base include inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonia. Further, a pH value may be adjusted by using a mineral acid such as sulfuric acid, hydrochloric acid or nitric acid as the metal dissolving agent. As a compound for adjusting the pH value, sulfuric acid or ammonia is preferred from the viewpoint of easiness of pH adjustment.

The pH of the polishing liquid for metal of the present embodiment can be measured by a pH meter (for example, Model pH Meter F-51 manufactured by HORIBA, Ltd.). For example, using a phthalate pH buffer (pH 4.01) and a neutral phosphate pH buffer (pH 6.86) as a standard buffer, the pH meter is calibrated at 2 points, and then the pH meter is The electrode was placed in a polishing liquid for metal, and the value which was stabilized after 2 minutes or more was measured. At this time, the liquid temperature of the standard buffer and the metal slurry was 25 °C.

The polishing liquid for metal of the present embodiment may further contain a metal oxidizing agent (hereinafter referred to as "metal oxidizing agent"). Examples of the metal oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), potassium periodate, and ozone water. Among the metal oxidizing agents, hydrogen peroxide is preferred.

The content of the metal oxidizing agent is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, further preferably 1 or more, based on 100 parts by mass of the polishing liquid, from the viewpoint of easily obtaining a good CMP rate. More than the mass. The content of the metal oxidizing agent is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, and still more preferably 3 parts by mass or less with respect to 100 parts by mass of the polishing liquid.

The polishing liquid for metal of the present embodiment may contain abrasive grains (abrasive grains) as needed. Examples of the abrasive grains include inorganic abrasive grains such as cerium oxide, aluminum oxide, cerium oxide, titanium oxide, zirconium oxide, cerium oxide, and cerium carbide; and organic abrasive grains such as polystyrene, polypropylene, and polyvinyl chloride; Composite abrasive grains of inorganic abrasive grains and organic abrasive grains, and the like. The abrasive grains are preferably inorganic abrasive grains, more preferably inorganic colloidal particles, and further preferably colloidal dioxide oxidation, from the viewpoint that the dispersion stability in the polishing liquid is good and the number of polishing damages generated during polishing is small. Bismuth, colloidal alumina, especially colloidal ceria.

The average particle diameter of the abrasive grains is not particularly limited, but is preferably 100 nm or less, and more preferably 80 nm or less from the viewpoint of excellent dispersion stability. The average particle diameter of the abrasive grains is preferably 10 nm or more, and more preferably 30 nm or more from the viewpoint of easily exhibiting a high CMP speed. The "average particle diameter" of the abrasive grains means the average secondary particle diameter of the abrasive grains in the polishing liquid for metal. For measuring the average particle diameter of the abrasive grains, for example, a light diffraction scattering type particle size distribution analyzer (for example, manufactured by COULTER Electronics Co., Ltd., trade name: COULTER N4SD; Malvern Instruments Co., Ltd.) Made by Malvern Instruments Ltd., trade name: Zetasizer 3000HSA).

From the viewpoint of suppressing the dispersion stability of the abrasive grains in the polishing liquid, the content of the abrasive grains is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, more preferably 5 parts by mass or less, more preferably 100 parts by mass of the polishing liquid. 1 part or less, It is especially preferably 0.5 parts by mass or less. When the abrasive grains are used, the content of the abrasive grains is preferably 0.01 parts by mass or more, and more preferably 0.05 parts by mass or more, based on 100 parts by mass of the polishing liquid, from the viewpoint of easily exhibiting a high CMP speed.

In the polishing liquid for metal of the present embodiment, the slurry and the additive liquid may be mixed to form the polishing liquid for metal, and may be stored as a plurality of liquid polishing liquid sets, and the plurality of liquid polishing liquid sets may be the polishing liquid. The constituent components are divided into a slurry and an additive liquid. The slurry contains at least, for example, abrasive grains and water. The addition liquid contains, for example, at least one selected from the group consisting of the above components (A) to (D) and a metal oxidizing agent. In particular, when a component which is easily decomposed is used (for example, when hydrogen peroxide is used as the metal oxidant, etc.), it is preferred to store the components separately. Preferably, it is divided into a slurry containing abrasive grains, the components (A) to (D) and water, and an additive liquid containing hydrogen peroxide and water.

Further, the slurry and the addition liquid may be a concentrated storage liquid which is used by being diluted with a liquid medium such as water. Here, the concentration means that the content ratio of each component to the liquid medium is larger than the content ratio of the metal polishing liquid, and is not limited to the material subjected to the concentration step.

[grinding method]

In the polishing method of the present embodiment, the metal is polished using the above-described polishing liquid for metal. The object to be polished in the polishing method of the present embodiment is not particularly limited as long as it has a metal. Preferably, the metal contains at least one type of copper-based metal selected from the group consisting of copper and copper alloy (copper). - chromium alloys, etc.), copper oxides and oxides of copper alloys. The object to be polished is preferably a substrate in which a metal is deposited on a bottom layer (a substrate, an interlayer insulating material, or the like) having a convex portion and a concave portion on the surface, and the concave portion is filled with a metal. If using the aforementioned metal slurry When such a substrate is ground, the metal deposited on the convex portion of the substrate or the interlayer insulating material is selectively ground and removed, and the desired planarized wiring pattern is preferably obtained.

In the polishing method of the present embodiment, for example, the substrate 10 shown in Fig. 1(a) is polished, the substrate 10 having a bottom layer 1 composed of a substrate 1a and an interlayer insulating material 1b and having a convex portion and a concave portion on the surface; The barrier material 2 is compliantly disposed on the surface of the underlayer 1; and the conductive material 3 is coated with the barrier material 2 so as to be embedded in the recess. The polishing method of the present embodiment includes, for example, a first polishing step of polishing the conductive material 3 using the polishing liquid for metal, and exposing the barrier material 2 on the convex portion of the underlayer 1 as shown in Fig. 1(b) The substrate 20 is obtained. Further, the polishing method of the present embodiment may include a second polishing step of polishing at least the barrier material 2 on the convex portion, and forming the underlayer 1 constituting the convex portion as shown in Fig. 1(c) (in Fig. 1) The interlayer insulating material 1b) is exposed to obtain the substrate 30.

In the polishing method of the present embodiment, for example, the polishing liquid for metal is supplied onto a polishing cloth of a polishing table, and the material to be polished having a substrate of a material to be polished (for example, the conductive material) is pressed against the polishing cloth. In this state, the polishing table is moved relative to the substrate, thereby grinding the material to be polished.

As the polishing device, for example, a general polishing device can be used, which has a holder that can maintain a ground substrate when being ground by a polishing cloth, and a polishing table that can be attached to the polishing cloth and can be rotated Several motors are connected. As the polishing cloth, a nonwoven fabric, a foamed polyurethane, a porous fluororesin or the like can be used.

The polishing conditions are not particularly limited, but the rotation speed of the polishing table is preferably a low rotation speed of 200 min ^-1 (200 rpm) or less to prevent the substrate from flying out. The pressure at which the substrate having the material to be polished is pressed onto the polishing cloth is preferably 4.9 to 98 kPa, and more preferably 9.8 to 49 kPa from the viewpoint of satisfying the following requirements: CMP speed deviation in the same plane is small (CMP speed In-plane uniformity), the irregularities existing before the polishing are easily eliminated and become flat (flatness of the pattern).

During the polishing, for example, a metal polishing liquid is continuously supplied to the polishing cloth by a pump or the like. The supply amount is not limited, but it is preferred that the surface of the polishing cloth is always covered with the polishing liquid. Preferably, the substrate after the completion of the polishing is carefully washed in running water, and then the water droplets adhering to the substrate are dropped by spin drying or the like and then dried.

Example

Hereinafter, the present invention will be described by way of examples. However, the invention is not limited to the embodiments.

[Preparation of polishing liquid for metal]

As shown in Tables 1 to 4, colloidal cerium oxide having an average particle diameter (secondary particle diameter) of 70 nm as abrasive abrasive grains, glycine acid as a metal dissolving agent, α-alanine acid, malic acid, and sulfuric acid were prepared. As a metal resist, methylbenzotriazole, benzotriazole, 1-hydroxybenzotriazole, and 1,2,4-triazole, three kinds of weight average molecular weights (Mw) as polymers Polyacrylic acid and polymethacrylic acid, ammonia water (25% by mass aqueous solution) as a pH adjuster, and hydrogen peroxide water (30% by mass aqueous solution) as a metal oxidizing agent. Each of the components (unit: parts by mass) shown in Tables 1 to 4 was mixed with pure water to prepare 100 parts by mass of a polishing liquid for metal.

The average particle diameter of the abrasive grains was measured using a light diffraction scattering type particle size distribution analyzer (manufactured by Malvern Instruments Co., Ltd., trade name: Zetasizer 3000HSA).

The pH of the polishing liquid for metal was measured by the following conditions. The measurement results are shown in Tables 1 to 4.

Measuring temperature: 25±5°C

Measuring device: Co., Ltd., manufactured by Horiba Co., Ltd. Model: pH Meter F-51

Determination method: 2-point calibration was performed using standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C); neutral phosphate pH buffer, pH 6.86 (25 ° C)). Then, the electrode was placed in a polishing liquid for metal, and the pH value which was stabilized after 2 minutes or more was measured by the above-described measuring device.

[Evaluation of grinding characteristics]

The polishing characteristics of the above-mentioned obtained metal slurry were evaluated by the evaluation items shown below. The evaluation results are shown in Tables 1 to 4.

(grinding conditions)

(1) Substrate: a copper substrate (8 inch wafer) having a thickness of 1 μm (blanket wafer)

(2) Grinding pressure: 14 kPa (2 psi)

(3) Relative speed of substrate and grinding platform: 36m/min

(4) Supply of polishing liquid: 200 mL/min

(5) Grinding device: Mirra manufactured by APPLIED MATERIALS Co., Ltd. (Applied Materials, Inc.), 8 inch wafer grinding device

(evaluation project)

(1) Polishing speed of CMP (CMP speed): The difference in thickness of copper before and after CMP was obtained from the resistance value conversion, and the CMP speed was calculated from the difference in thickness and the polishing time.

(2) Etching speed: 100 mL of the above-mentioned metal slurry obtained was measured in a 100 mL glass beaker. The metal slurry was heated to 60 ° C, and a ruthenium wafer processed to 20 mm × 20 mm was immersed in a slurry stirred at a number of revolutions of 200 min ^-1 for 2 min. The difference in thickness of copper before and after immersion was obtained from the resistance value conversion, and the etching rate was calculated from the difference in thickness and the immersion time.

(3) Abrasive damage: Using a Complus manufactured by APPLIED MATERIALS Co., Ltd., a defect of 0.2 μm or more on the copper surface after CMP was detected. Further, the copper surface was observed using the defect detection coordinates obtained by Complus and SEM Vision manufactured by APPLIED MATERIALS Co., Ltd., only the abrasive damage was extracted, and the number of grinding damages was calculated.

As shown in Examples 1 to 20, when the component (A) to the component (D) specified in the present application were used in combination, the following results were obtained: a higher CMP rate and a lower etching rate were observed, and the polishing damage was less. .

Moreover, as shown in the embodiments 11 to 13, 16 to 18, when the application is used in combination The specific component (A) to component (D), and having a pH of 4.5 to 5.0, exhibits a lower etching rate and less abrasive damage, and an exceptionally high CMP rate is obtained.

On the other hand, as shown in Comparative Examples 1, 2, 4 and 5, when a compound having a benzotriazole skeleton was used alone as a metal resist, the polishing damage was large.

As shown in Comparative Example 3, when 1-hydroxybenzotriazole was used alone as a metal resist, the polishing damage became very small, but did not exhibit a low etching rate.

As shown in Comparative Example 6, when a compound having a benzotriazole skeleton was used alone as a metal resist, and the component (D) was not added, a high polishing rate was not obtained, and the polishing damage was large.

As shown in Comparative Examples 7 and 8, when the pH was too large, a higher polishing speed was not obtained, and the polishing damage was large.

As shown in Comparative Example 9, when a compound having a benzotriazole skeleton was used alone as a metal resist, and the weight average molecular weight of the component (D) was small, a high polishing rate was not obtained, and the etching rate was not obtained. It becomes lower and the grinding damage is more.

As shown in Comparative Examples 10 to 13, when a compound having a benzotriazole skeleton was used alone as a metal resist, a high CMP rate was not obtained and the polishing damage was large.

As shown in Comparative Example 14, when a compound having a benzotriazole skeleton was used alone as a metal resist, and malic acid was used alone as a metal dissolving agent, the etching rate did not become low, and the polishing damage was large.

As shown in Comparative Example 15, when the ratio of the content of the metal resist to the content of the component (D) was too large, a high CMP rate was not obtained, the etching rate was not lowered, and the polishing damage was large.

As shown in Comparative Example 16, when the weight average molecular weight of the component (D) was small, a high CMP rate was not obtained, the etching rate was not lowered, and the polishing damage was large.

As shown in Comparative Example 17, when 1-hydroxybenzotriazole was used, but other compounds did not have a benzotriazole skeleton, a higher CMP rate was not obtained, and the etching rate did not become low, and More abrasive damage

As shown in Comparative Example 18, when the ratio of the content of the metal resist to the content of the component (D) was too small, a high polishing rate was not obtained, the etching rate was not lowered, and the polishing damage was large.

As shown in Comparative Example 19, when the pH was too small, a high polishing rate was not obtained, the etching rate did not become low, and the polishing damage was large.

As shown in Comparative Example 20, when malic acid was used alone as the metal dissolving agent without using the amino acid, a higher polishing rate was not obtained, the etching rate was not lowered, and the polishing damage was high.

Claims (7)

A metal slurry for grinding at least a portion of a metal and comprising: (A) an amino acid; (B) 1-hydroxybenzotriazole; (C) a compound having a benzotriazole skeleton (however, (except for 1-hydroxybenzotriazole); and, (D) a polymer having at least one structural unit derived from (meth)acrylic acid selected from the group consisting of (meth)acrylic acid a structural unit of a salt, a structural unit derived from (meth)acrylamide, and a structural unit derived from an amino (meth) acrylamide; wherein the weight average molecular weight of the component (D) is 10,000 or more, the above ( The mass ratio of the content of the component B) and the content of the component (C) to the content of the component (D) (the total of the component (B) and the component (C)/(D) component is 0.15 to 3.00, The pH is 3.0 to 6.0. The polishing liquid for metal according to claim 1, wherein the component (A) contains glycine. The metal slurry according to claim 1 or claim 2, wherein the pH is 4.5 to 5.0. The polishing liquid for metal according to any one of claims 1 to 3, Further, it further contains at least one selected from the group consisting of hydrogen peroxide, potassium periodate, and ozone water. The polishing liquid for metal according to any one of claims 1 to 4, further comprising abrasive grains. The polishing liquid for metal according to any one of claims 1 to 5, wherein the metal comprises at least one selected from the group consisting of copper, copper alloy, copper oxide, and copper alloy. Oxide. A polishing method for polishing at least a part of the aforementioned metal using the polishing liquid for metal according to any one of claims 1 to 6.