JP2008091569A - Polishing composition and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing compound and a polishing method which can control such phenomena as scratching, thinning, dishing, erosion, and the like, over a long term in polishing of an insulating film (Low-k film) having a relative dielectric constant of 3.0 or less. <P>SOLUTION: The polishing compound used for polishing an insulating film having an organic siloxane structure and a dielectric constant of 3.0 or less chemically and mechanically contains colloidal silica particles, a benzotriazole compound and a secondary or tertiary aminoalcohol represented by formula (I), wherein the pH is in the range of 7-10. A polishing method employing that polishing compound is also provided. In the formula (I), R<SB>1</SB>, R<SB>2</SB>and R<SB>3</SB>are each independently a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the aliphatic hydrocarbon group and the aromatic hydrocarbon group may be further replaced by an amino group, a hydroxy group, a carboxy group or a hydrocarbon group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polishing composition and a polishing method for performing chemical mechanical planarization at the time of polishing a semiconductor device, for example.

In the development of a semiconductor device represented by a semiconductor integrated circuit (hereinafter referred to as LSI), in recent years, in order to reduce the size and increase the speed, there has been a demand for higher density and higher integration by miniaturizing and stacking wiring. In order to increase the speed of the LSI, an interlayer insulating film used in the LSI is required to have a material with a low dielectric constant and a low inter-wiring capacitance.
Conventionally, SiO ₂ is used as an interlayer insulating film material of a semiconductor device, and a relative dielectric constant is about 3.8 to 4.2. However, as the line width becomes narrower, the relative dielectric constant of the interlayer insulating film material must also be lowered. For example, an element having a line width of 130 nm requires a material with a relative dielectric constant of about 2.5 to 3.0. And

As a material used for forming an insulating film having a low relative dielectric constant (hereinafter also referred to as a low-k film) as an interlayer insulating film, a SiOC-based material (for example, a plurality of Si—C or Si—H bonds) is used. Organic-inorganic hybrid materials such as SiOC and MSQ are known.
Specifically, as a material used for forming an insulating film having a relative dielectric constant, there are HSG-R7 (Hitachi Chemical Co., Ltd.), BLACKDIAMOND (Applied Materials, Inc.) and the like in the SiOC system.

These Low-k films are required to be planarized for miniaturization of LSIs.
As a method for planarizing the Low-k film, Patent Document 1 discloses a planarization method using a CMP technique, that is, a method of polishing using cerium oxide particles as abrasive grains. Here, CMP is an abbreviation for Chemical Mechanical Polishing. Generally, a polishing pad is affixed on a circular polishing platen (platen), and the surface of the polishing pad is immersed in a polishing composition. Then, press the surface of the substrate (wafer) against the pad and rotate the polishing surface plate and the substrate while applying a predetermined pressure (polishing pressure) from the back surface, and the mechanical friction that occurs causes the surface to be polished to move. The surface is flattened.

However, the method of polishing using cerium oxide particles as the abrasive grains has a low polishing rate, and the polishing composition used for flattening the low-k film has a high concentration of abrasive particles. Cheap. In particular, when a low-k film is planarized using a polishing composition in which abrasive particles are aggregated by long-term storage, stress concentration occurs during polishing, and polishing scratches (scratches) are likely to occur. Therefore, there is a need for a technique that can suppress aggregation of particles of the polishing composition over a long period of time and suppress scratches in flattening the low-k film.
JP 2000-286255 A

The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to achieve the following object.
That is, the present invention suppresses agglomeration of abrasive particles contained in the polishing composition for a long period of time, and scratches in polishing an insulating film (Low-k film) having an organosiloxane structure and a relative dielectric constant of 3.0 or less. An object of the present invention is to provide a polishing composition capable of suppressing the generation of rust and a polishing method using the same.

In view of the above circumstances, the present inventors have conducted intensive research and found that the above problems can be solved by using a polishing method using a polishing composition having a specific composition, thereby completing the present invention.
That is, the present invention is achieved by the following means.

<1> In a semiconductor device manufacturing method, the insulating film of an object to be polished having an embedded wiring on an insulating film having an organosiloxane structure with a relative dielectric constant of 3.0 or less via a barrier metal layer is chemically and mechanically polished. A polishing composition used for polishing, comprising colloidal silica particles, a benzotriazole compound, and a secondary or tertiary amino alcohol represented by the following formula (I), and having a pH in the range of 7 to 10 Composition.

[In the above formula (I), R ₁ , R ₂ and R ₃ each independently represents a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the aliphatic hydrocarbon group and the aromatic carbon group The hydrogen group may be further substituted with an amino group, a hydroxy group, a carboxy group, or a hydrocarbon group. However, at least one terminal of R ₁ , R ₂ , R ₃ has a hydroxy group. Further, at least two of R ₁ , R ₂ and R ₃ are substituents other than hydrogen atoms. ]

<2> The polishing composition according to <1>, wherein the concentration of the colloidal silica particles is 0.5 to 15% by mass.

<3> The benzotriazole compound is 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- [ <1> or <2>, which is at least one compound selected from N, N-bis (hydroxyethyl) aminomethyl] benzotriazole and 1- (hydroxymethyl) benzotriazole Polishing composition.

<4> Polishing by supplying a polishing composition to a polishing pad on a polishing surface plate and rotating the polishing surface plate so that the polishing pad moves relative to the insulating film of the object to be polished. The insulating film is an insulating film of the object to be polished, in which an embedded wiring is formed through a barrier metal layer in an insulating film having an organic siloxane structure and a relative dielectric constant of 3.0 or less, and A polishing method, wherein the polishing composition is the polishing composition according to any one of <1> to <3>.

<5> The load (polishing pressure) when the polishing pad is brought into contact with the insulating film of the object to be polished is 0.69 kPa (0.007 kgf / cm ² ) to 21.6 kPa (0.22 kgf / cm ² ). The polishing method according to <4>, which is characterized.

<6> According to <4> or <5>, wherein the supply flow rate when supplying the polishing composition to the polishing pad on the polishing surface plate is 0.035 to 0.60 ml / min · cm ^2. The polishing method described.

  According to the present invention, the agglomeration of abrasive particles contained in a polishing composition is suppressed for a long period of time, and scratches are produced in polishing an insulating film (Low-k film) having an organosiloxane structure and a relative dielectric constant of 3.0 or less. The composition for polishing which can suppress generation | occurrence | production of this, and the grinding | polishing method using the same can be provided.

  The polishing composition of the present invention is a chemical mechanical component for forming a buried wiring through a barrier metal layer in a low-k film having an organosiloxane structure and having a relative dielectric constant of 3.0 or less in the production of a semiconductor device. A polishing composition used for polishing, comprising colloidal silica particles, a benzotriazole compound and a secondary or tertiary amino alcohol represented by the following formula (I), having a pH in the range of 7 to 10. .

In the above formula (I), R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the aliphatic hydrocarbon group and the aromatic hydrocarbon The group may be further substituted with an amino group, a hydroxy group, a carboxy group, or a hydrocarbon group. However, at least one terminal of R ₁ , R ₂ , R ₃ has a hydroxy group. Further, at least two of R ₁ , R ₂ and R ₃ are substituents other than hydrogen atoms.

  Hereinafter, the constituent elements of the polishing composition of the present invention will be sequentially described.

[Low dielectric constant insulating film]
The insulating film in the present invention is an insulating film having an organic siloxane structure and a low relative dielectric constant of 3.0 or less (hereinafter, appropriately referred to as “Low-k film”).
As a material used for forming the insulating film having a low relative dielectric constant, a material for forming an insulating film having an organosiloxane structure and having a relative dielectric constant of 3.0 or less can be used without any particular limitation.
Organic materials such as SiOC having an organic siloxane structure (for example, a plurality of Si—C or SiOC containing Si—H bonds), MSQ and the like are preferable.

  As said organosiloxane structure, what is represented by following formula (II) is mentioned, for example.

In the above formula (II), R ₄ represents a hydrogen atom, a hydrocarbon group or OR ₆ , and R ₅ represents a hydrocarbon group or OR ₇ . R ₆ and R ₇ each independently represents a hydrocarbon group.

In the above formula (II), examples of the hydrocarbon group represented by R _{4 to} R ₇ include an aliphatic hydrocarbon group and an aromatic hydrocarbon group.

Specific examples of materials that can be used for forming the insulating film having a low relative dielectric constant include SiOG-based materials such as HSG-R7 (Hitachi Chemical Industry: 2.8), BLACKDIAMMOND (Applied Materials, Inc: 2. 4-3.0), p-MTES (Hitachi Development: 3.2), Coral (Novellus Systems, Inc: 2.4-2.7) ), Aurora (Japan MS: 2.7), and MSQ systems include OCDT-9 (Tokyo Ohka Kogyo: 2.7), LKD-T200 (JSR: 2.5-2.7), HOSP (Honeywell Electronic Materials: 2.5), HSG-RZ25 (Hitachi Chemical Industry: 2.5), OCLT-31 (Tokyo Ohka Kogyo: 2.3), LKD-T400 (JSR: 2.0-2) .2), HSG-6221X (manufactured by Hitachi Chemical Co., Ltd .: 2.1), ALCAP-S (manufactured by Asahi Kasei Kogyo Co., Ltd .: 1.8-2.3), OCLT-77 (manufactured by Tokyo Ohka Kogyo Co., Ltd .: 1.9-2. 2), HSG-6221X (manufactured by Hitachi Chemical Co., Ltd .: 2.4), silica aerogel (manufactured by Kobe Steel: 1.1-1.4), and the like, but are not limited thereto. .

  The material that can form the insulating film having a low relative dielectric constant may be used alone or in combination. Furthermore, these materials may be in a form having minute holes.

In the present invention, the insulating film may be formed by plasma CVD or spin coating.
The dielectric constant of the insulating film having a low relative dielectric constant in the present invention is required to be 3.0 or less, but is preferably low, and particularly preferably 1.8 to 2.8.
Setting the relative dielectric constant in the range of 1.8 to 2.8 is preferable in that the effect of the present invention, that is, suppression of generation of scratches due to suppression of agglomeration of abrasive particles for a long period of time becomes significant.
The relative dielectric constant in the present invention can be measured with a precision 4284A LCR meter with respect to a solid film, a measurement method using a mercury probe, and a relative dielectric constant of an insulating film provided with wiring. These methods were adopted for the relative dielectric constant in the present invention.

  Conventionally, a general dielectric material is a material having a relative dielectric constant of about 3.8 to 4.2. As the line width decreases, the dielectric constant must also decrease. For example, a device having a line width of 130 nm requires a material having a relative dielectric constant of about 2.5 to 3.0. A material referred to as a low relative dielectric constant usually has a relative dielectric constant of about 2.0 to 2.5. An element having a line width of 90 nm has a relative dielectric constant of less than 2.4. In an element having a line width of 90 nm, the relative dielectric constant is less than 2.4. From such a point, the polishing composition of the present invention is remarkably effective when used for flattening a wiring width narrower than a device having a line width of 130 nm.

[Polishing composition]
The polishing composition of the present invention comprises (a) colloidal silica particles, (b) a benzotriazole compound, and (c) a secondary or tertiary amino alcohol represented by the formula (I).

(A) Colloidal silica particles The polishing composition used in the present invention contains colloidal silica particles as a constituent component. Colloidal silica particles are contained as abrasive particles.
Examples of the method for producing the colloidal silica particles include silicon alkoxides such as Si (OC ₂ H ₅ ) ₄ , Si (sec-OC ₄ H ₉ ) ₄ , Si (OCH ₃ ) ₄ , and Si (OC ₄ H ₉ ) _4. It can be obtained by hydrolyzing the compound by a sol-gel method. Such colloidal silica particles have a very sharp particle size distribution.

  The particle size of the colloidal silica particles in the present invention is a particle size cumulative curve (frequency distribution curve) showing the relationship between the particle size of the colloidal silica particles and the cumulative frequency obtained by integrating the number of particles having the particle size. The particle diameter at the point where the cumulative frequency is 50% is meant. The particle diameter of the colloidal silica particles represents an average particle diameter determined in the particle size distribution obtained from the dynamic light scattering method. As the measuring device for obtaining the particle size distribution, for example, LB-500 manufactured by HORIBA, Ltd. is used.

  5-60 nm is preferable and, as for the average particle diameter of the colloidal silica particle to contain, More preferably, it is 5-30 nm. Particles of 5 nm or more are preferable for the purpose of achieving a sufficient polishing speed. The particle diameter is preferably 60 nm or less for the purpose of preventing excessive frictional heat during polishing.

It is preferable that the density | concentration of the colloidal silica particle which is an abrasive particle is contained in the ratio of 0.5-15 mass% in the total mass of polishing composition. More preferably, it is the range of 1-10 mass%. The concentration is preferably 0.5% by mass or more for the purpose of achieving a sufficient polishing speed. Further, the concentration is preferably 10% by mass or less for the purpose of not generating excessive frictional heat during polishing.
Further, the polishing composition of the present invention can be used as it is or in a diluted form, but even when the polishing composition is used after being diluted, the concentration in the polishing composition dilution liquid at the time of use is the composition. This is the same as the product concentration range, and the preferred range is also the same.

(B) Benzotriazole compound The polishing composition of the present invention contains a benzotriazole compound.
In the present invention, as the benzotriazole compound, 1,2,3-benzotriazole (BTA), 5,6-dimethyl-1,2,3-benzotriazole (DBTA), 1- (1,2-dicarboxyethyl) ) One or more compounds selected from benzotriazole (DCEBTA), 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole (HEABTA) and 1- (hydroxymethyl) benzotriazole (HMBTA). preferable.
Among the above, more preferable benzotriazole compounds include 5,6-dimethyl-1,2,3-benzotriazole (DBTA), 1- (1,2-dicarboxyethyl) benzotriazole (DCEBTA), 1- [ N, N-bis (hydroxyethyl) aminomethyl] benzotriazole (HEABTA), 1- (hydroxymethyl) benzotriazole (HMBTA).
The benzotriazole compounds used in the present invention may be used alone or in combination of two or more.
The concentration of the benzotriazole compound is not particularly limited, but is preferably 0.01% by mass to 0.2% by mass, and more preferably 0.05% by mass to 0.2% by mass. is there.

(C) Secondary or tertiary amino alcohol The polishing composition of the present invention contains a secondary or tertiary amino alcohol represented by the following formula (I).

In the above formula (I), R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the aliphatic hydrocarbon group and the aromatic hydrocarbon The group may be further substituted with an amino group, a hydroxy group, a carboxy group, or a hydrocarbon group. However, at least one terminal of R ₁ , R ₂ , R ₃ has a hydroxy group. Further, at least two of R ₁ , R ₂ and R ₃ are substituents other than hydrogen atoms.

Examples of the aliphatic hydrocarbon group represented by R ₁ , R ₂ , or R ₃ in the above formula (I) include an aliphatic hydrocarbon group having 1 to 15 carbon atoms. Preferably, C2-C6 is more preferable. The aliphatic hydrocarbon group may be chain-like, cyclic or branched. The aliphatic hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group (excluding an aromatic hydrocarbon group).
Specific examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, and a t-butyl group.

Examples of the aromatic hydrocarbon group represented by R ₁ , R ₂ , and R ₃ in the above formula (I) include a phenyl group, a naphthyl group, and an anthryl group.

When R ₁ , R ₂ , R _{3 in the} above formula (I) represent an aliphatic hydrocarbon group or an aromatic hydrocarbon group, these are further substituted with an amino group, a hydroxy group, a carboxy group, or a hydrocarbon group. The substituent may be a hydroxy group or an amino group.
Specific examples of the aliphatic hydrocarbon group or aromatic hydrocarbon group further having a substituent as described above include, for example, —CH ₂ CH ₂ OH, —CH ₂ CH ₂ CH ₂ OH, —C (CH _{2 OH) 3, -CH 2 CH} 2 NH 2, -C 6 H 4 OH , and the like.

Further, these may be those in which one or more carbon atoms are substituted with a heteroatom (preferably nitrogen or oxygen).

Preferable specific examples of the secondary or tertiary amino alcohol represented by the above formula (1) include, for example, compounds A-1 to A-19 shown in Table 1 below. In Table 1 below, compounds A-1 to A-19 are represented by describing R ₁ , R ₂ , and R ₃ in the above formula (1). However, the secondary or tertiary amino alcohol is not limited to these.

  Among the specific examples (compounds A-1 to A-19) of the secondary or tertiary amino alcohols shown in Table 1, A-1, A-7, A-9, A-10, A-11, A -12, A-13, A-14, A-17, and A-19 are preferable from the viewpoint of preventing aggregation, and A-9 and A-17 are more preferable.

  As the secondary or tertiary amino alcohol that can be used in the present invention, a commercially available product or a synthesized product may be used.

  The secondary or tertiary amino alcohol that can be used in the present invention may be used alone or in combination of two or more. The concentration of the secondary or tertiary amino alcohol is not particularly limited, but is preferably 0.01 to 10% by mass and more preferably 0.1 to 5% by mass from the viewpoint of particle dispersibility in the polishing composition.

[PH]
The polishing composition of the present invention needs to be in the range of pH 7.0 to 10. The polishing composition of the present invention exhibits an excellent effect on the particle dispersibility of the polishing composition when the pH is in this range.
Furthermore, the pH of the polishing composition of the present invention is preferably 8.0 to 10, particularly preferably 8.5 to 10, from the viewpoint of particle dispersibility of the polishing composition.
In the present invention, an alkali / acid or a buffer may be used to adjust the pH to a range of 7.0 to 10.

  Examples of the alkali / acid or buffer include non-metallic alkali such as ammonia, organic ammonium hydroxide such as ammonium hydroxide and tetramethylammonium hydroxide, alkanolamines such as diethanolamine, triethanolamine and triisopropanolamine. Agents, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, inorganic acids such as nitric acid, sulfuric acid and phosphoric acid, carbonates such as sodium carbonate, phosphates such as trisodium phosphate, boron Preferable examples include acid salts, tetraborate salts, hydroxybenzoate salts, and the like. Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkali / acid or buffer may be an amount that maintains the pH in the range of 7.0 to 10, and 0.0001 mol in 1 L of the polishing composition when used for polishing. It is preferable to set it as -1.0 mol, and it is more preferable to set it as 0.003 mol-0.5 mol.

〔Oxidant〕
The polishing composition of the present invention preferably contains a compound (oxidant) that can oxidize and polish a metal.
Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, Examples thereof include dichromate, permanganate, ozone water, silver (II) salt, and iron (III) salt. Among them, hydrogen peroxide is preferably used.
Examples of the iron (III) salt include, in addition to inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III), iron bromide (III), and iron (III) Organic complex salts are preferably used.

  The addition amount of the oxidizing agent is preferably 0.01 mol to 1 mol, and particularly preferably 0.05 mol to 0.6 mol, in 1 L of the polishing composition.

[Chelating agent]
The polishing composition of the present invention preferably contains a chelating agent as necessary in order to reduce adverse effects such as mixed polyvalent metal ions.
Chelating agents include general water softeners and related compounds that are calcium and magnesium precipitation inhibitors, such as nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid, ethylenediamine -N, N, N ', N'-tetramethylenesulfonic acid, transcyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form) ), N- (2-carboxylateethyl) -L-aspartic acid, β-alanine diacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N, N '-Bis (2-hydroxybenzyl) Ethylenediamine -N, N'-diacetic acid, 1,2-dihydroxy-4,6-disulfonic acid.

[Organic acid]
The polishing liquid in the present invention can further contain an organic acid.
The organic acid here is a compound having a structure different from that of an oxidizing agent for oxidizing a metal, and does not include an acid that functions as the above-described oxidizing agent. The acid here has an action of promoting oxidation, adjusting pH, and buffering agent.
As the organic acid, one selected from the following group is suitable.
That is, 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-methyl Hexanoic 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, apple Examples thereof include acids, tartaric acid, citric acid, lactic acid, and salts thereof such as ammonium salts and alkali metal salts, sulfuric acid, nitric acid, ammonia, ammonium salts, and mixtures thereof.
Among these, formic acid, malonic acid, malic acid, tartaric acid, and citric acid are suitable for laminated films including at least one metal layer selected from copper, copper alloys, and copper or copper alloy oxides. is there.

An amino acid can be mentioned as an organic acid in this invention.
The amino acid is preferably water-soluble, and more preferably selected from the following group.
That is, for example, glycine, L-alanine, β-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-tyrosine, 3,5-diiodo-L-tyrosine, β- ( 3,4-dihydroxyphenyl) -L-alanine, L-thyroxine, 4-hydroxy-L-proline, L-cystine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-cystine, L- Cysteic acid, L-aspartic acid, L-glutamic acid, S- (carboxymethyl) -L-cysteine, 4- Aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-quinurenin, L-histidine, 1-methyl-L-histidine It is desirable to contain at least one of amino acids such as 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipine.
Among these, malic acid, tartaric acid, citric acid, glycine, and glycolic acid are particularly preferable in that the etching rate can be effectively suppressed while maintaining a practical CMP rate.

  The amount of the organic acid added is preferably 0.0005 mol to 0.5 mol, more preferably 0.005 mol to 0.3 mol, and more preferably 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. The amount is particularly preferably 0.1 mol. That is, the addition amount of the organic acid is preferably 0.5 mol or less from the viewpoint of suppressing etching, and 0.0005 mol or more is preferable for obtaining a sufficient effect.

[Polishing method]
The polishing method of the present invention supplies a polishing composition to a polishing pad on a polishing surface plate, and rotates the polishing surface plate to cause the polishing pad to move relative to the insulating film of the object to be polished. A polishing method for polishing, wherein the insulating film has an organosiloxane structure and has a relative dielectric constant of 3.0 or less, and an embedded wiring is formed through a barrier metal layer on the insulating film of the object to be polished. And the polishing composition is the polishing composition of the present invention.
A polishing method capable of suppressing the generation of scratches in the polishing of a low dielectric constant insulating film (Low-k film) formed using a material having a relative dielectric constant of 3.0 or less. It can be.

  In the polishing method of the present invention, the low relative dielectric constant insulating film (Low-k film) formed using the material having a relative dielectric constant of 3.0 or less is the above-mentioned item of the polishing composition of the present invention. Are the same as described above, and preferred examples are also the same.

The polishing composition of the present invention comprises: 1. A concentrated liquid which is diluted by adding water or an aqueous solution when used. 2. When each component is prepared in the form of an aqueous solution described in the next section, these are mixed, and if necessary diluted with water to make a working solution. It may be prepared as a working solution.
The polishing composition in any case is applicable to the polishing method using the polishing composition of the present invention.
This polishing method is a method in which a polishing composition is supplied to a polishing pad on a polishing surface plate and brought into contact with the surface to be polished of the object to be polished so that the surface to be polished and the polishing pad move relative to each other.

  As an apparatus used for polishing, a holder for holding an object to be polished (for example, a wafer on which a conductive material film is formed) having a surface to be polished and a polishing pad are attached (a motor capable of changing the number of rotations). Etc.) and a general polishing apparatus having a polishing surface plate.

Specific examples of the polishing apparatus include: Mirra Mesa CMP, Reflexion CMP (Applied Materials), FREX200, FREX300 (Ebara Manufacturing), NPS3301, NPS2301 (Nikon), A-FP-310A, A-FP-210A (Tokyo Seimitsu) ), 2300 TERES (Ram Research), Momentum (Speedfam IPEC), and the like.
As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation. Details will be described later.
The polishing conditions are not limited, but the rotation speed of the polishing surface plate is preferably a low rotation of 200 rpm or less so that the object to be polished does not pop out.
The pressing pressure of the object to be polished having the surface to be polished (film to be polished) against the polishing pad is preferably 0.68 to 34.5 KPa, more preferably 0.69 to 21.6 KPa, and polishing. In order to satisfy the in-plane uniformity of the object to be polished and the flatness of the pattern, it is more preferably 3.40 to 20.7 KPa.

  During polishing, the polishing composition is continuously supplied to the polishing pad with a pump or the like. After the polishing is finished, the object to be polished is thoroughly washed in running water, and then dried after removing water droplets adhering to the object to be polished using a spin dryer or the like.

In the present invention, the 1. When diluting the concentrated solution as in the above method, the following aqueous solutions can be used. The aqueous solution is water containing at least one of an oxidizing agent, a secondary or tertiary amino alcohol, an additive, and a surfactant in advance, and the components contained in the aqueous solution and the concentrated liquid to be diluted. A component obtained by adding up the components contained therein is made to be a component of the polishing composition (use liquid) used when polishing.
Thus, when the concentrate is diluted with an aqueous solution and used, components that are difficult to dissolve can be added later in the form of an aqueous solution, so that a more concentrated concentrate can be prepared.

  In addition, as a method of diluting by adding water or an aqueous solution to the concentrate, a pipe for supplying a concentrate having a composition in which the polishing composition is concentrated and a pipe for supplying water or an aqueous solution are joined together and mixed, There is a method of supplying a used liquid of a polishing composition mixed and diluted to a polishing pad. Mixing of concentrated liquid with water or aqueous solution is a method in which liquids collide with each other through a narrow passage under pressure, filling the pipe with a filler such as a glass tube, and separating and separating the liquid flow. Ordinary methods such as a method of repeatedly performing and a method of providing a blade rotating with power in the pipe can be employed.

The supply flow rate of the polishing composition is preferably 10 to 1000 ml / min, and more preferably 170 to 800 ml / min in order to satisfy the in-plane uniformity of the polishing rate and the flatness of the pattern.
The supply flow rate per unit area of the polishing composition is preferably 0.035 to 0.60 ml / cm ² .

  Furthermore, as a method of polishing while diluting the concentrate with water or an aqueous solution, a pipe for supplying the concentrate and a pipe for supplying water or an aqueous solution are provided independently, and a predetermined amount of liquid is supplied to the polishing pad from each. There is a method of supplying and polishing while mixing by the relative motion of the polishing pad and the surface to be polished. Alternatively, a method may be used in which a predetermined amount of concentrated liquid and water or an aqueous solution are mixed in a single container, and then the mixed polishing composition is supplied to a polishing pad to perform polishing.

Further, as another polishing method, the component to be contained in the polishing composition is divided into at least two constituent components, and when using them, a polishing pad on a polishing surface plate is diluted by adding water or an aqueous solution. And the surface to be polished is brought into contact with the surface to be polished, and the surface to be polished and the polishing pad are moved relative to each other for polishing.
For example, an oxidizing agent is a component (A), a secondary or tertiary amino alcohol, an additive, a surfactant, and water is a component (B). A) and component (B) can be diluted and used.
Further, an additive having low solubility is divided into two components (A) and (B). For example, an oxidizing agent, an additive, and a surfactant are used as a component (A), and a secondary or tertiary amino alcohol is added. An agent, a surfactant, and water are used as the constituent component (B), and when they are used, water or an aqueous solution is added to dilute the constituent component (A) and the constituent component (B). In these cases, the colloidal silica particles (abrasive grains) in the present invention are preferably contained in the constituent component (A).

In the case of the above example, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are required, and dilution mixing supplies the three pipes to the polishing pad. There is a method of connecting to one pipe and mixing in the pipe. In this case, it is possible to connect two pipes and then connect another pipe. Specifically, this is a method in which a constituent component containing an additive that is difficult to dissolve is mixed with another constituent component, a mixing path is lengthened to ensure a dissolution time, and then a water or aqueous solution pipe is further coupled. .
As described above, the other mixing methods are as follows. The three pipes are directly guided to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished, or the three components are mixed in one container. There is a method of supplying a diluted polishing composition from there to a polishing pad.

  In the above polishing method, when one constituent component containing an oxidizing agent is made 40 ° C. or lower and the other constituent components are heated in the range of room temperature to 100 ° C., one constituent component and another constituent component are mixed. Alternatively, when diluting by adding water or an aqueous solution, the liquid temperature can be set to 40 ° C. or lower. This method is a preferable method for increasing the solubility of the raw material having a low solubility of the polishing composition by utilizing the phenomenon that the solubility becomes high when the temperature is high.

  The raw materials in which the above other components are dissolved by heating in the range of room temperature to 100 ° C. are precipitated in the solution when the temperature is lowered. It is necessary to dissolve the raw material deposited by heating. For this purpose, there are provided means for heating and feeding the other constituents in which the raw material is dissolved, and means for stirring and feeding the liquid containing the precipitate, and heating and dissolving the piping. Can be adopted. When the temperature of one constituent component containing an oxidizing agent is increased to 40 ° C. or higher, the other constituent components that have been heated may be decomposed. When two components are mixed, it is preferable that the temperature be 40 ° C. or lower.

Thus, in the present invention, the components of the polishing composition may be divided into two or more parts and supplied to the surface to be polished. In this case, it is preferable to divide and supply the component containing an oxide and the component containing a secondary or tertiary amino alcohol. Alternatively, the polishing composition may be used as a concentrated liquid and supplied to the surface to be polished separately from the dilution water.
In the present invention, in the present invention, when applying a method of dividing the components of the polishing composition into two or more parts and supplying them to the surface to be polished, the supply amount is the sum of the supply amounts from the respective pipes. It represents.

〔pad〕
The polishing pad for polishing applicable to the polishing method of the present invention may be a non-foamed structure pad or a foamed structure pad. The former uses a hard synthetic resin bulk material like a plastic plate for a pad. Further, the latter further includes three types of a closed foam (dry foam system), a continuous foam (wet foam system), and a two-layer composite (laminated system), and a two-layer composite (laminated system) is particularly preferable. Foaming may be uniform or non-uniform.
Further, it may be one containing abrasive grains generally used for polishing (for example, ceria, silica, alumina, resin, etc.). In addition, the hardness may be either soft or hard, and either may be used. In the laminated system, it is preferable to use a different hardness for each layer.
As the material, non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate and the like are preferable. Further, the surface contacting the surface to be polished may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

[Wafer]
In the present invention, the wafer as the object to be polished by CMP with the polishing composition preferably has a diameter of 200 mm or more, and particularly preferably 300 mm or more. The effect of the present invention is remarkably exhibited when the thickness is 300 mm or more.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

<Example 1>
Each polishing composition shown below was prepared, and its abrasive particle dispersion stability and scratch performance were evaluated by a time test.

(Preparation of polishing composition)
The following composition was mixed to prepare a polishing composition.
Hydrogen peroxide (oxidant) 10g / L
A-1: Diethanolamine (secondary amino alcohol, manufactured by Wako Pure Chemical Industries, Ltd.) 24 g / L
1H-benzotriazole (BTA: aromatic ring compound) 0.5 g / L
Colloidal silica particles (PL-3, primary particle size 15 nm,
Degree of association 4, secondary particle size 40 nm) 50 g / L (converted into powder)
Add pure water, total volume 1000mL
pH (adjusted with aqueous ammonia and sulfuric acid) 9.5

(Evaluation method of abrasive particle dispersion stability)
For each adjusted slurry, the aggregation change of each slurry was observed with a Turbi scan (manufactured by Eihiro Seiki Co., Ltd .: Turbi scan MA2000). In the evaluation, the transmitted light intensity of the slurry was traced from 0 day to 180 days (this evaluation shows that the smaller the change in transmitted light intensity, the better the dispersion stability of the abrasive particles).

The evaluation criteria of the abrasive particle dispersion stability are as follows.
○: Time change after 6 months (change in transmitted light intensity) is 10% or less △: Time change after 6 months (change in transmitted light intensity) is less than 21% ×: Time change after 6 months (change in transmitted light intensity) is 21% In addition, (circle) and (triangle | delta) are judged to be a level which does not have a problem practically.

(Scratch performance evaluation method)
For scratch performance, BD wafers (BLACKDIAMOND, Applied Materials, Inc.) are polished and then washed with pure water, dried and observed with an optical microscope, and the polished surface state based on the following evaluation criteria Was evaluated.
This evaluation was performed immediately after the preparation and after confirmation of the aging test after 180 days.

The evaluation criteria for scratch performance are as follows.
○: Scratch is hardly generated and good Δ: A small number of scratches of 1 μm or more are observed ×: Many scratches of 1 μm or more are observed Note that ○ and Δ are levels having no practical problem.

<Examples 2 to 21>
Polishing was performed in the same manner as in Example 1 except that the A-1 compound (secondary amino alcohol) in the preparation of the polishing composition of Example 1 was changed to the secondary or tertiary amino alcohol described in Table 2. The composition was adjusted and evaluated.
However, in Examples 20 and 21, a mixture of two kinds and three kinds of secondary or tertiary amino alcohols shown in Table 2 is used.

<Comparative Examples 1-2>
In Comparative Example 1, adjustment and evaluation of the polishing composition were performed in the same manner as in Example 1 except that the A-1 compound (secondary amino alcohol) in the adjustment of the polishing composition of Example 1 was excluded. Went. In Comparative Example 2, the polishing composition of Example 1 was carried out in the same manner as in Example 1 except that the A-1 compound (secondary amino alcohol) in the preparation of the polishing composition of Example 1 was changed to lactic acid. Adjustments and evaluations were made.

The time-dependent changes in particle dispersion stability in Examples 1, 9, 15 and Comparative Examples 1-2 are shown in FIG. Table 2 shows the evaluation results of Examples 1-21 and Comparative Examples 1-2.
In Comparative Examples 1 and 2, the scratch performance after 180 days could not be evaluated due to the abrasive particle aggregation of the polishing composition.

  As is clear from Table 2, in Examples 1 to 21, the particle dispersibility of the polishing composition was stable over a long period of time, and the scratch performance in polishing of the BD wafer could be kept good. On the other hand, in Comparative Examples 1 and 2, the dispersion stability of the polishing composition decreased with time, and scratches due to particle aggregation occurred over time during polishing of the BD wafer.

It is a graph which shows the time-dependent change of the particle dispersion stability in Examples 1, 9, 15 and Comparative Examples 1-2.

Claims (6)

In a semiconductor device manufacturing method, in order to chemically and mechanically polish the insulating film of an object to be polished having an embedded wiring through a barrier metal layer on an insulating film having an organosiloxane structure and a relative dielectric constant of 3.0 or less A polishing composition to be used, comprising colloidal silica particles, a benzotriazole compound, and a secondary or tertiary amino alcohol represented by the following formula (I), and having a pH of 7 to 10 .

[In the above formula (I), R ₁ , R ₂ and R ₃ each independently represents a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the aliphatic hydrocarbon group and the aromatic carbon group The hydrogen group may be further substituted with an amino group, a hydroxy group, a carboxy group, or a hydrocarbon group. However, at least one terminal of R ₁ , R ₂ , R ₃ has a hydroxy group. Further, at least two of R ₁ , R ₂ and R ₃ are substituents other than hydrogen atoms. ]   The polishing composition according to claim 1, wherein the concentration of the colloidal silica particles is 0.5 to 15% by mass.   The benzotriazole compound is 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- [N, N The polishing composition according to claim 1 or 2, which is at least one compound selected from -bis (hydroxyethyl) aminomethyl] benzotriazole and 1- (hydroxymethyl) benzotriazole.   A polishing method in which a polishing composition is supplied to a polishing pad on a polishing platen, and the polishing surface is rotated by rotating the polishing platen while the polishing pad is in contact with an insulating film of an object to be polished, thereby polishing the contact surface. And the insulating film is an insulating film of the object to be polished formed by forming an embedded wiring through a barrier metal layer in an insulating film having an organic siloxane structure and having a relative dielectric constant of 3.0 or less, and A polishing method, wherein the polishing composition is the polishing composition according to claim 1. The load (polishing pressure) when the polishing pad is brought into contact with the insulating film of the object to be polished is 0.69 kPa (0.007 kgf / cm ² ) to 21.6 kPa (0.22 kgf / cm ² ). The polishing method according to claim 4. The polishing method according to claim 4 or 5, wherein a supply flow rate when the polishing composition is supplied to the polishing pad on the polishing surface plate is 0.035 to 0.60 ml / min · cm ² .

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