JP2009088080A - Polishing liquid for chemical mechanical polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polishing solution for chemical-mechanical polishing which can prevent the occurrence of dishing or erosion effectively while exhibiting high polishing speed for an insulating film. <P>SOLUTION: The polishing solution used for chemical-mechanical polishing in a fabrication process of semiconductor device contains colloidal silica particles, a benzotriazol based compound represented by general formula (I), an oxidant, and an at least bivalent ammonium cation compound. In the general formula (I), R<SP>1</SP>-R<SP>5</SP>represents a hydrogen atom, an unsubstituted or substituted alkyl group, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing liquid, and more particularly to a chemical mechanical polishing polishing liquid that can be suitably used in a semiconductor device manufacturing process.

  In the development of semiconductor devices represented by semiconductor integrated circuits (hereinafter referred to as LSIs), in recent years, there has been a demand for higher density and higher integration by miniaturization and stacking of wiring in order to reduce the size and increase the speed. . For this purpose, various techniques such as chemical mechanical polishing (hereinafter referred to as CMP) have been used. This CMP is an indispensable technique for surface flattening of processed films such as interlayer insulation films, plug formation, formation of embedded metal wiring, etc., and smoothing of the substrate and removal of excess metal thin film during wiring formation In addition, an excess barrier layer on the insulating film is removed.

A general method of CMP is to apply a polishing pad on a circular polishing platen (platen), immerse the polishing pad surface with a polishing liquid, and press the surface of the substrate (wafer) against the pad (surface to be polished) In a state where a predetermined pressure (polishing pressure) is applied from the back surface, both the polishing platen and the substrate are rotated, and the surface of the substrate is flattened by the generated mechanical friction.
When manufacturing semiconductor devices such as LSI, fine wiring is formed in multiple layers, and when forming metal wiring such as Cu in each layer, diffusion of wiring material to the interlayer insulating film In order to prevent this and to improve the adhesion of the wiring material, a barrier metal film such as Ta, TaN, Ti, or TiN is formed in advance.

In order to form each wiring layer, first, CMP of a metal film (hereinafter referred to as metal film CMP) for removing excess wiring material stacked by plating or the like is performed in one or more stages. Next, CMP (hereinafter referred to as “barrier metal CMP”) is generally performed to remove the barrier metal material (barrier metal) exposed on the surface. However, there is a problem that the metal film CMP causes so-called dishing in which the wiring portion is excessively polished and further causes erosion.
In barrier metal CMP performed after metal film CMP in order to reduce dishing, a wiring layer having few steps such as dishing and erosion is finally adjusted by adjusting the polishing speed of the metal wiring portion and the polishing speed of the barrier metal portion. Is required to form. That is, in the barrier metal CMP, when the polishing rate of the barrier metal or the interlayer insulating film is relatively small compared to the metal wiring material, dishing such as polishing of the wiring portion is caused and erosion as a result is generated. Therefore, it is desirable that the polishing rate of the barrier metal or the insulating film layer is appropriately high. This has the advantage of increasing the throughput of barrier metal CMP, and in fact, dishing is often caused by metal film CMP, and relative polishing rates of barrier metal and insulating film layers are relatively high for the reasons described above. This is also desirable in that it is required to be higher.

The metal polishing solution used for CMP generally contains abrasive grains (for example, alumina and silica) and an oxidizing agent (for example, hydrogen peroxide and persulfuric acid). It is considered that the basic mechanism is polishing by oxidizing the metal surface with an oxidizing agent and removing the oxide film with abrasive grains.
However, when CMP is performed using a polishing liquid containing such solid abrasive grains, polishing scratches, a phenomenon in which the entire polished surface is polished more than necessary (thinning), and the polished metal surface has a dish-like shape. In some cases, a phenomenon in which an insulator between metal wirings is polished more than necessary, and a plurality of metal surfaces of the wiring are recessed in a dish shape (erosion).
Moreover, the use of a polishing liquid containing solid abrasive grains complicates the cleaning process normally performed to remove the polishing liquid remaining on the semiconductor surface after polishing, and further, the cleaning liquid (waste liquid) is removed. In order to process, there exists a problem in terms of cost, for example, it is necessary to settle and separate solid abrasive grains.

For the polishing liquid containing such solid abrasive grains, the following various proposals have been made. For example, a CMP polishing agent and a polishing method (for example, refer to Patent Document 1) aiming at high-speed polishing with almost no polishing scratches generated, a polishing composition and a polishing method with improved cleaning performance in CMP (for example, , And Patent Document 2) and a polishing composition (see, for example, Patent Document 3) that prevents aggregation of abrasive grains have been proposed.
JP 2003-17446 A JP 2003-142435 A JP 2000-84832 A

  An object of the present invention is to provide a polishing solution for chemical mechanical polishing which has a high polishing rate for an insulating film and can effectively suppress the occurrence of dishing and erosion.

<1> A polishing liquid used for chemical mechanical polishing in a semiconductor device manufacturing process, comprising colloidal silica particles, a benzotriazole-based compound represented by the following general formula (I), an oxidant, and a divalent or higher valence A polishing liquid for chemical mechanical polishing, comprising:

In general formula (I), R ^{1 to} R ⁵ each independently represents a hydrogen atom, an unsubstituted or substituted alkyl group.

<2> The polishing solution for chemical mechanical polishing according to <1>, wherein the divalent or higher ammonium cation compound is a compound represented by the following general formula (II).

In General Formula (II), R ^{6 to} R ¹¹ each independently represent an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and 2 of R ^{6 to} R ¹¹ May be joined together. These may be further substituted with other functional groups such as an alkyl group, a hydroxyl group, an amino group, and a carboxyl group. X represents an alkylene group having 1 to 30 carbon atoms, an alkenylene group, a cycloalkylene group, an arylene group, or a linking group obtained by combining these groups, and this linking group further includes an alkyl group, a hydroxyl group, an amino group, a carboxyl group, and the like. And may further contain a quaternary amine nitrogen. n represents an integer of 2 or more.

<3> The chemical according to <1> or <2>, wherein the content of the colloidal silica particles is in a range of 0.05% by mass to 15% by mass with respect to the total mass of the polishing liquid. Polishing liquid for mechanical polishing.

<4> The chemical mechanical polishing polishing liquid according to any one of <1> to <3>, wherein a primary average particle diameter of the colloidal silica particles is in a range of 5 nm to 100 nm.

<5> The chemical mechanical polishing according to any one of <1> to <4>, wherein the benzotriazole-based compound is selected from unsubstituted benzotriazole or a benzotriazole derivative having an alkyl substituent. Polishing fluid.

<6> Further, pectic acid, agar, polyvinyl alcohol, polyvinyl pyrrolidone, polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid) Acid), polyacrylamide, polyacrylic acid, polyamic acid, polyacrylic acid sodium salt, and at least one water-soluble polymer selected from polyglyoxylic acid, any one of <1> to <5> A polishing liquid for chemical mechanical polishing according to claim 1.

<7> The chemical machine according to any one of <1> to <6>, further comprising at least one organic acid selected from the group of compounds having at least one carboxyl group in the molecule Polishing liquid for mechanical polishing.

<8> The polishing liquid according to any one of <1> to <7>, wherein the pH is 2 or more and 5 or less.

<9> The chemical mechanical polishing polishing liquid according to any one of <1> to <8>, further comprising a nonionic surfactant or an anionic surfactant.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing liquid for chemical mechanical polishing which can suppress the generation | occurrence | production of dishing and erosion effectively with the high grinding | polishing speed | rate with respect to an insulating film is provided.

  Hereinafter, the polishing liquid of the present invention will be specifically described. In the present invention, the “polishing liquid” means not only a polishing liquid used for polishing (that is, a polishing liquid diluted as necessary) but also a concentrated liquid of the polishing liquid. The concentrated liquid or the concentrated polishing liquid means a polishing liquid prepared with a higher solute concentration than the polishing liquid used for polishing, and is diluted with water or an aqueous solution when used for polishing. And used for polishing. The dilution factor is generally 1 to 20 volume times. In this specification, “concentration” and “concentrated liquid” are used in accordance with conventional expressions meaning “thick” and “thick liquid” rather than the state of use, and generally involve physical concentration operations such as evaporation. The term is used in a different way from the meaning of common terms.

  The polishing liquid for chemical mechanical polishing of the present invention comprises (1) colloidal silica particles, (2) a benzotriazole compound represented by the following general formula (I), (3) an oxidizing agent, and (4) 2 And an ammonium cation compound having a valence higher than that.

In the general formula (I), R ^{1 to} R ⁵ each independently represents a hydrogen atom, an unsubstituted or substituted alkyl group.

(1) Colloidal silica particles The polishing liquid of the present invention contains colloidal silica as at least a part of the abrasive grains.
The colloidal silica is preferably colloidal silica which does not contain impurities such as alkali metals inside the particles and is obtained by hydrolysis of alkoxysilane. On the other hand, although colloidal silica produced by a method of removing alkali from an alkali silicate aqueous solution can also be used, in this case, there is a concern that the alkali metal remaining in the particles gradually elutes and affects the polishing performance. . From such a viewpoint, a material obtained by hydrolysis of alkoxysilane is more preferable as a raw material.
The particle diameter of the colloidal silica is appropriately selected according to the purpose of use of the abrasive grains, but from the viewpoint of effectively suppressing the generation of polishing flaws, the primary average particle diameter is preferably in the range of 5 nm to 100 nm, A range of 10 nm to 70 nm is more preferable.

  The content (concentration) of the colloidal silica in the polishing liquid of the present invention is the polishing liquid used for polishing (that is, the diluted polishing liquid when diluted with water or an aqueous solution. Is preferably 0.05 mass% to 15 mass%, more preferably 3 mass% to 12 mass%, particularly preferably 5 mass%. % To 12% by mass. That is, the content of colloidal silica is preferably 0.05% by mass or more in terms of polishing the insulating film at a sufficient polishing rate, and preferably 15% by mass or less in terms of storage stability.

In the polishing liquid of the present invention, abrasive grains other than colloidal silica can be used in combination as long as the effects of the present invention are not impaired, but even in that case, the content ratio of colloidal silica in all abrasive grains is preferably Is 50% by mass or more, and particularly preferably 80% by mass or more. All of the contained abrasive grains may be colloidal silica.
Examples of abrasive grains that can be used in combination with colloidal silica for the polishing liquid of the present invention include fumed silica, ceria, alumina, and titania. The size of these combined abrasive grains is preferably equal to or more than that of colloidal silica and is twice or less.

(2) Benzotriazole compound The polishing liquid of the invention contains a benzotriazole compound (BTA compound) represented by the following general formula (I).

In formula (I), R ^{1 to} R ⁵ each independently represents a hydrogen atom, an unsubstituted or substituted alkyl group.

  The BTA compound represented by the general formula (I) acts as a corrosion inhibitor that adsorbs to the surface to be polished to form a film and controls the corrosion of the metal surface. As the BTA compound added to the polishing liquid of the present invention, those selected from unsubstituted benzotriazole or benzotriazole derivatives having an alkyl substituent are preferable, and specifically, compounds shown in the following B1 to B15 However, it is not limited to these.

  The addition amount of the BTA compound represented by the general formula (I) is preferably 0.0001% by mass or more and 1% by mass or less, and 0.001% by mass or more with respect to the mass of the polishing liquid when used for polishing. 0.5 mass% or less is still more preferable. That is, the addition amount of such a corrosion inhibitor is preferably 0.0001% by mass or more from the viewpoint of not expanding dishing, and is preferably 1% by mass or less from the viewpoint of storage stability.

(3) Oxidizing agent The polishing liquid of the present invention contains a compound (oxidizing agent) that oxidizes a metal to be polished.
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.
The iron (III) salt includes, for example, iron (III) in addition to inorganic iron (III) salts such as iron (III) nitrate, iron (III) chloride, iron (III) sulfate and iron (III) bromide. ) Organic complex salts are preferably used.

  The addition amount of the oxidizing agent can be adjusted by the dishing amount at the initial stage of the barrier CMP. When the amount of dishing at the beginning of barrier CMP is large, that is, when it is not desired to polish the wiring material very much in barrier CMP, it is desirable to add a small amount of oxidizer, the dishing amount is sufficiently small, and the wiring material can be removed at high speed. When polishing is desired, it is desirable to increase the addition amount of the oxidizing agent. As described above, it is desirable to change the addition amount of the oxidizing agent depending on the dishing situation in the initial stage of the barrier CMP. Specifically, the amount may be 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. Preferably, 0.05 mol to 0.6 mol is particularly preferable.

(4) Bivalent or higher ammonium cation compound The polishing liquid of the present invention contains a bivalent or higher ammonium cation compound (hereinafter sometimes referred to as a specific cation compound). The divalent or higher valent ammonium cation compound added to the polishing liquid of the present invention is not particularly limited as long as it is divalent or higher and includes a quaternary nitrogen in the molecular structure. From the viewpoint of achieving the improvement, a divalent or higher valent ammonium cation compound represented by the following general formula (II) is preferable.

In General Formula (II), R ^{6 to} R ¹¹ each independently represent an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and 2 of R ^{6 to} R ¹¹ May be joined together. These may be further substituted with other functional groups such as an alkyl group, a hydroxyl group, an amino group, and a carboxyl group. X represents an alkylene group having 1 to 30 carbon atoms, an alkenylene group, a cycloalkylene group, an arylene group, or a linking group obtained by combining these groups, and this linking group further includes an alkyl group, a hydroxyl group, an amino group, a carboxyl group, and the like. And may further contain a quaternary amine nitrogen. n represents an integer of 2 or more.

Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Among them, a methyl group, An ethyl group, a propyl group, and a butyl group are preferable.
Moreover, as said alkenyl group, a C2-C10 thing is preferable, and an ethynyl group, a propyl group, etc. are mentioned specifically ,.

Specific examples of the cycloalkyl group include a cyclohexyl group and a cyclopentyl group, and among them, a cyclohexyl group is preferable.
Specific examples of the aryl group include a butynyl group, a pentynyl group, a hexynyl group, a phenyl group, and a naphthyl group, and among them, a phenyl group is preferable.
Specific examples of the aralkyl group include a benzyl group, and among them, a benzyl group is preferable.

  Each of the above groups may further have a substituent, and examples of the substituent that can be introduced include a hydroxyl group, an amino group, a carboxyl group, a phosphate group, an imino group, a thiol group, a sulfo group, and a nitro group. Can be mentioned.

X in the general formula (II) represents an alkylene group having 1 to 30 carbon atoms, an alkenylene group, a cycloalkylene group, an arylene group, or a linking group in which two or more of these groups are combined.
In addition to the above organic linking group, the linking group represented by X includes —S—, —S (═O) ₂ —, —O—, —C (═O) — in the chain. May be included.

Specific examples of the alkylene group having 1 to 10 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, and an octylene group. Among them, an ethylene group, A pentylene group is preferred.
Specific examples of the alkenylene group include an ethynylene group and a propynylene group, and among them, a propynylene group is preferable.
Specific examples of the cycloalkylene group include a cyclohexylene group and a cyclopentylene group. Among them, a cyclohexylene group is preferable.
Specific examples of the arylene group include a phenylene group and a naphthylene group, and among them, a phenylene group is preferable.

  Each of the above linking groups may further have a substituent, and examples of the substituent that can be introduced include a hydroxyl group, an amino group, a carboxyl group, a phosphate group, an imino group, a thiol group, a sulfo group, and a nitro group. Can be mentioned.

  Hereinafter, although the specific example [Exemplary compound (C1)-(C45)] of the bivalent or more valent ammonium cation compound which can be contained in the polishing liquid of this invention is shown, this invention is not limited to these.

In the compounds exemplified above, n is an integer of 2 or more. X in the compound represented by C44 is an integer of 1 to 50, and y is an integer of 1 to 50. In the compound represented by C45, a is an integer of 1 to 50, and b is an integer of 1 to 50.
The specific cation compound in the present invention can be synthesized, for example, by a substitution reaction in which ammonia, various amines and the like serve as a nucleophile.
Moreover, the purchase as a general sale reagent is also possible.

  The addition amount of the divalent or higher ammonium cation compound in the present invention is preferably 0.0001% by mass or more and 1% by mass or less, and 0.001% by mass or more and 0.3% by mass with respect to the polishing liquid used for polishing. % Or less is more preferable. That is, the amount of the specific cation compound added is preferably 0.0001% by mass or more from the viewpoint of sufficiently improving the polishing rate, and is preferably 0.3% by mass or less from the viewpoint of sufficient slurry stability. .

(5) Other components In addition to the components (1) to (4), various components can be added to the polishing liquid of the present invention depending on the purpose. The components that can be contained in the polishing liquid of the present invention are described below.

-Water-soluble polymer-
The polishing liquid of the present invention may further contain a water-soluble polymer from the viewpoint of achieving further high planarization, preferably pectic acid, agar, polyvinyl alcohol, polyvinyl pyrrolidone, polyaspartic acid, polyglutamic acid, Polylysine, polymalic acid, polymethacrylic acid, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylamide, polyacrylic acid, polyamic acid, polyacrylic acid sodium salt, and polyglyoxylic acid At least one water-soluble polymer selected from the group consisting of:

The addition amount of the water-soluble polymer is preferably from 0.001 g to 10 g, more preferably from 0.01 g to 1 g, in 1 L of a polishing liquid used for polishing, from the viewpoint of stability over time.
In addition, the weight average molecular weight of the water-soluble polymer is preferably 200 to 50000, more preferably 1000 to 30000, from the viewpoint of stability over time.

-Surfactant-
The polishing liquid of the present invention may further contain a surfactant.
In the polishing liquid of the present invention, it is possible to improve the polishing rate and more suitably control the polishing rate of the insulating layer by adjusting the type and amount of the surfactant. As the surfactant, a nonionic surfactant or an anionic surfactant is preferably used.
Among these, from the viewpoint of improving the polishing rate of the insulating layer, a compound represented by the following general formula (III) is preferable, and from the viewpoint of suppressing the polishing rate of the insulating layer, a compound represented by the following general formula (IV) preferable.

  In the general formula (III), R represents a hydrocarbon group, preferably a hydrocarbon group having 6 to 20 carbon atoms. Specifically, for example, an alkyl group having 6 to 20 carbon atoms, an aryl group (for example, a phenyl group, a naphthyl group, and the like) are preferable, and the alkyl group and the aryl group further have a substituent such as an alkyl group. It may be.

  Specific examples of the compound represented by the general formula (III) include, for example, decylbenzenesulfonic acid, dodecylbenzenesulfonic acid (DBSA), tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, dodecylnaphthalenesulfonic acid, tetradecyl. And compounds such as naphthalenesulfonic acid.

In the general formula (IV), R ^{a to} R ^d each independently represent a hydrocarbon group having 1 to 18 carbon atoms. However, R ^{a to} R ^d are not all the same hydrocarbon group.
Examples of the hydrocarbon group represented by R ^{a to} R ^d include an alkyl group, an aryl group, and a phenyl group, and among them, a linear and branched alkyl group having 1 to 20 carbon atoms is preferable.
Two of R ^{a to} R ^d may be bonded to each other to form a cyclic structure such as a pyridine structure, a pyrrolidine structure, a piperidine structure, or a pyrrole structure.

  Specific examples of the compound represented by the general formula (IV) include compounds such as lauryltrimethylammonium, lauryltriethylammonium, stearyltrimethylammonium, palmityltrimethylammonium, octyltrimethylammonium, dodecylpyridinium, decylpyridinium, octylpyridinium, and the like. Is mentioned.

As the surfactant in the present invention, those other than the compound represented by the general formula (III) or (IV) may be used. For example, an anion other than the compound represented by the general formula (III) Examples of the surfactant include carboxylate, sulfate ester salt, and phosphate ester salt.
More specifically, as the carboxylate, soap, N-acyl amino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxylate, acylated peptide;
As sulfate salts, sulfated oils, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkyl amide sulfates;
As the phosphate ester salt, an alkyl phosphate, polyoxyethylene or polyoxypropylene alkylallyl ether phosphate can be preferably used.

  The total amount of the surfactant added is preferably 0.001 to 10 g, more preferably 0.01 to 5 g in 1 liter of polishing liquid when used for polishing. It is particularly preferable that That is, the addition amount of the surfactant is preferably 0.01 g or more for obtaining a sufficient effect, and preferably 1 g or less from the viewpoint of preventing the CMP rate from being lowered.

-Compound having a carboxyl group (organic acid)-
The polishing liquid of the present invention may further contain at least one organic acid selected from the group of compounds having at least one carboxyl group in the molecule.
The organic acid is not particularly limited as long as it is a compound having at least one carboxyl group in the molecule, but it is preferable to select a compound represented by the following general formula (V) from the viewpoint of the polishing rate structure.
In addition, it is preferable that the number of the carboxyl groups which exist in a molecule | numerator is 1-4, and it is more preferable that it is 1-2 from a viewpoint which can be used cheaply.

In the general formula (V), R ⁷ and R ⁸ each independently represent a hydrocarbon group, preferably a C 1-10 hydrocarbon group.
R ⁷ is a monovalent hydrocarbon group, for example, an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, a cycloalkyl group, etc.), an aryl group (for example, a phenyl group), an alkoxy group, an aryloxy group Groups and the like are preferred.
R ⁸ is a divalent hydrocarbon group, for example, an alkylene group having 1 to 10 carbon atoms (for example, a methylene group or a cycloalkylene group), an arylene group (for example, a phenylene group), an alkyleneoxy group, or the like. preferable.
The hydrocarbon group represented by R ⁷ and R ⁸ may further have a substituent. Examples of the substituent that can be introduced include an alkyl group having 1 to 3 carbon atoms, an aryl group, an alkoxy group, and a carboxyl group. Group, etc., and when it has a carboxyl group as a substituent, this compound has a plurality of carboxyl groups.
R ⁷ and R ⁸ may be bonded to each other to form a cyclic structure.

Examples of the compound having a carboxyl group (organic acid) in the present invention include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, and 2-ethylbutyric acid. 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutar Acids, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, and salts thereof such as ammonium salts and alkali metal salts, sulfuric acid, nitric acid, ammonia, ammonium salts, or mixtures thereof Etc.
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.

As the compound (organic acid) having a carboxyl group in the present invention, amino acids and the like can be mentioned as suitable ones. As this amino acid and the like, water-soluble ones are preferable, and those selected from the following groups are more suitable.
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.

  In the polishing liquid of the present invention, the amount of the compound having a carboxyl group (preferably, the compound represented by the general formula (V)) is 0.1 mass relative to the mass of the polishing liquid when used for polishing. % To 5% by mass is preferable, and 0.5% to 2% by mass is more preferable. That is, the content of such a compound having a carboxyl group (organic acid) is preferably 0.1% by mass or more in terms of achieving a sufficient polishing rate, and 5% by mass from the point of not causing excessive dishing. The following is preferred.

-PH adjuster-
The polishing liquid of the present invention preferably has a pH of 2 or more and 5 or less. By controlling the pH of the polishing liquid in the range of 2 to 5, the polishing rate of the interlayer insulating film can be adjusted more reliably.
Therefore, an alkali / acid or a buffering agent can be used as necessary to adjust the pH to the above preferred range.
Examples of alkali / acid or buffering agents include non-metallic alkaline agents such as organic ammonium hydroxides such as ammonia, ammonium hydroxide and tetramethylammonium hydroxide, alkanolamines such as diethanolamine, triethanolamine and triisopropanolamine. 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, boric acid Preferable examples include salts, tetraborate and hydroxybenzoate. Particularly preferred alkaline agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkali / acid or the buffer may be an amount that maintains the pH within a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of the polishing liquid when used for polishing. , 0.003 mol to 0.5 mol is more preferable.

-Chelating agent-
The polishing liquid of the present invention preferably contains a chelating agent (that is, a hard water softening 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-hydroxyben Le) ethylenediamine -N, N'-diacetic acid, 1,2-dihydroxy-4,6-disulfonic acid.

Two or more chelating agents may be used in combination as necessary.
The addition amount of the chelating agent may be an amount sufficient to sequester metal ions such as mixed polyvalent metal ions, for example, 0.0003 mol to 0.07 mol in 1 L of a polishing liquid used for polishing. Add to be.

  Next, the object to be polished when polishing using the polishing liquid of the present invention will be described. When the polishing liquid of the present invention is used, the polishing target is not particularly limited. For example, in a semiconductor device manufacturing process, an interlayer insulating film, a barrier layer, and a copper or copper alloy conductive film are provided on a silicon substrate. It can be suitably used in a polishing process for planarizing the surface of a semiconductor substrate (wafer).

[Barrier metal material]
As a material constituting the barrier layer of the semiconductor substrate to be polished, generally a low-resistance metal material is preferable, and TiN, TiW, Ta, TaN, W, WN are particularly preferable, and Ta and TaN are particularly preferable. .

[Interlayer insulation film]
As an interlayer insulating film (insulating layer), in addition to a commonly used interlayer insulating film such as TEOS, for example, a low dielectric constant material having a relative dielectric constant of about 3.5 to 2.0 (for example, organic polymer, SiOC And an interlayer insulating film including an abbreviated low-k film).
Specifically, HSG-R7 (Hitachi Chemical Industry), BLACKDIAMOND (Applied Materials, Inc), SilK (The Dow Chemical Co), Aurora (Japan M.) and Coral (Novellus Systems, Inc.). Such a Low-k film is usually located under the TEOS insulating film, and a barrier layer and a metal wiring are formed on the TEOS insulating film.
Especially the polishing liquid of this invention can improve the grinding | polishing rate of an interlayer insulation film (insulation layer) by combined use with a specific cation compound and colloidal silica.

[Raw metal materials]
In the present invention, the object to be polished preferably has a wiring made of a copper metal and / or a copper alloy as applied to a semiconductor device such as an LSI. In particular, a copper alloy is preferable as a raw material for the wiring. Furthermore, the copper alloy containing silver is preferable among copper alloys.
In addition, the silver content contained in the copper alloy is preferably 40% by mass or less, particularly 10% by mass or less, more preferably 1% by mass or less, and a copper alloy in the range of 0.00001 to 0.1% by mass. The most excellent effect is exhibited.

[Wiring thickness]
In the present invention, when the object to be polished is applied to, for example, a DRAM device system, it preferably has a wiring with a half pitch of 0.15 μm or less, more preferably 0.10 μm or less, and further Preferably it is 0.08 micrometer or less.
On the other hand, when the object to be polished is applied to, for example, an MPU device system, it is preferable to have a wiring of 0.12 μm or less, more preferably 0.09 μm or less, and still more preferably 0.07 μm or less.
The polishing liquid of the present invention described above exhibits a particularly excellent effect on the object to be polished having such wiring.

[Polishing method]
The polishing liquid of the present invention is (a) a concentrated liquid, and when used to dilute by adding water or an aqueous solution, (b) each component is prepared in the form of an aqueous solution described later, When these are mixed and diluted with water as necessary to obtain a use solution, (c) the use solution may be prepared.
Any type of polishing liquid can be applied to the polishing method using the polishing liquid of the present invention. Basically, the polishing liquid is supplied to the polishing pad on the polishing surface plate, and the surface to be polished of the object to be polished Is brought into contact with the polishing pad and the surface to be polished and the polishing pad are moved relative to each other for polishing.

  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. As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation. 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 having the surface to be polished (film to be polished) against the polishing pad is preferably 0.68 to 34.5 KPa, the in-plane uniformity of the object to be polished at the polishing rate and the flatness of the pattern In order to satisfy the properties, it is more preferably 3.40 to 20.7 KPa.

During polishing, the polishing liquid of the present invention is continuously supplied to the polishing pad with a pump or the like.
After the polishing is completed, 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, when diluting the concentrate as in the method (a), the following aqueous solutions can be used. For example, an aqueous solution containing at least one of an oxidizing agent, an organic acid, an additive, and a surfactant is prepared in advance, and the components contained in the aqueous solution and the concentrated solution to be diluted are contained. A component obtained by summing up the component and the component is used as a component of a polishing liquid (use liquid) used for 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 the concentrated liquid by adding water or an aqueous solution, the pipe for supplying the concentrated polishing liquid and the pipe for supplying the water or the aqueous solution are mixed together and mixed, and the polishing diluted by mixing is performed. There is a method of supplying a liquid to be used to the 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. Known methods such as a method of repeatedly performing and a method of providing blades that rotate by power in the piping can be employed.

  The supply rate of the polishing liquid is preferably 10 to 1000 ml / min, and more preferably 170 to 800 ml / min in order to satisfy the in-surface uniformity of the polishing rate and the flatness of the pattern.

  Further, as a method of polishing while diluting the concentrated liquid with water or an aqueous solution, a pipe for supplying the polishing liquid and a pipe for supplying the water or the aqueous solution are provided independently, and a predetermined amount of liquid is respectively applied to the polishing pad. There is a method of supplying and polishing while mixing by the relative motion of the polishing pad and the surface to be polished. It is also possible to use a method in which a predetermined amount of concentrated liquid and water or an aqueous solution are mixed in one container and then the mixed polishing liquid is supplied to the polishing pad for polishing.

In addition, as another polishing method, the component to be contained in the polishing liquid is divided into at least two components, and when these are used, water or an aqueous solution is added and diluted and supplied to the polishing pad on the polishing platen Then, there is a method in which the surface to be polished and the polishing pad are moved relative to each other and brought into contact with the surface to be polished for polishing.
For example, an oxidant is used as the component (A), an organic acid, an additive, a surfactant, and water are used as the component (B). A component (B) can be diluted and used.
Further, an additive having low solubility is divided into two constituent components (A) and (B). For example, an oxidizing agent, an additive, and a surfactant are used as the constituent component (A), and an organic acid, an additive, and a surface active agent are used. An agent and water are used as the component (B), and when they are used, water or an aqueous solution is added to dilute the component (A) and the component (B).

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 diluted polishing liquid to the polishing pad from there.

  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. In general, this method is a preferable method for increasing the solubility of a raw material having a low solubility of the polishing liquid by utilizing the phenomenon that the solubility is increased 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, a means for heating and feeding other constituents in which the raw material is dissolved and a means for stirring the liquid containing the precipitate and heating and dissolving the pipe for feeding the liquid are adopted. can do. 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 liquid 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 an organic acid. Alternatively, the polishing liquid may be a concentrated liquid and supplied to the surface to be polished separately from the dilution water.
In the present invention, when a method of supplying a polishing liquid component into two or more parts and supplying it to the surface to be polished is applied, the supply amount represents the total supply amount from each pipe.

〔pad〕
The polishing pad 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.). 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, a wafer as an object to be subjected to CMP with the polishing liquid preferably has a diameter of 200 mm or more, particularly preferably 300 mm or more. The effect of the present invention is remarkably exhibited when the thickness is 300 mm or more.

[Polishing equipment]
The apparatus for carrying out polishing using the polishing liquid of the present invention is not particularly limited. For example, Mira Mesa CMP, Reflexion CMP (Applied Materials), FREX200, FREX300 (Ebara Seisakusho), NPS3301, NPS2301 (Nikon), A- FP-310A, A-FP-210A (Tokyo Seimitsu), 2300 TERES (Ram Research), Momentum (Speedfam IPEC), etc. can be mentioned.

  Hereinafter, although an example and a comparative example are explained, the present invention is not limited by these examples.

[Example 1]
A polishing liquid having the composition and pH shown below was prepared.
Abrasive particles: Colloidal silica particles A1 100 g / L (* powder conversion)
BTA compound: BTA derivative B1 1.0 g / L
Specific cationic compound: Cationic agent C1 0.2 g / L
Oxidizing agent: Hydrogen peroxide 5g / L
Add pure water, total volume 1000mL
pH (adjusted with ammonia water and nitric acid) 3.5
The shape and particle size of the colloidal silica particles A1 are as shown in Table 1 below, and the BTA derivative B1 and the cation agent C1 are the exemplified compounds described above.

Polishing evaluation was performed using the said polishing liquid.
(Evaluation methods)
Using a device “MA-300D” manufactured by Musashino Electronics Co., Ltd. as a polishing apparatus, the wafer shown below was polished under the following conditions while supplying slurry.
Table rotation speed: 112 rpm
Head rotation speed: 113 rpm
Polishing pressure: 9.19 kPa
Polishing pad: Rodel Nitta Co., Ltd. IC1400 XY-K-Pad
Polishing liquid supply speed: 50 ml / min

<Polishing rate evaluation>
As a wafer for polishing rate evaluation, a cut wafer obtained by cutting an 8-inch wafer in which a polishing object (TEOS: tetraethoxysilane) was formed on a Si substrate into 6 cm × 6 cm was used.

<Dishing and erosion evaluation>
As a wafer for dishing and erosion evaluation, a silicon oxide film on the Si substrate is patterned by a photolithography process and a reactive ion etching process to form wiring grooves and connection holes having a width of 0.09 to 100 μm and a depth of 600 nm. did. Further, a Ta film having a thickness of 20 nm was formed by a sputtering method, and then a copper film having a thickness of 50 nm was formed by a sputtering method. Thereafter, a wafer (commonly called 854PTN wafer) on which a copper film having a total thickness of 1000 nm was formed by plating was cut into 6 × 6 cm and used. Further, a wafer in which the copper film was separately polished with slurry until the Ta film surface appeared was used as an evaluation wafer. The initial steps of the used wafers were all 10 nm or less.
The time when the wafer was polished for 60 seconds was defined as the polishing end point. The polished wafer was evaluated using a stylus-type level difference meter, measuring the level difference of an isolated wiring with a width of 100 μm for dishing evaluation, and measuring the level difference of 9 μm / 1 μm line / space for erosion evaluation. .

[Examples 2-45 and Comparative Examples 1-3]
Polishing liquids having the compositions and pH shown in Tables 2 to 5 were prepared, and polishing experiments were performed under the same polishing conditions as in Example 1. The abrasive particles A1 to A6 are as shown in Table 1.
Experimental results are also shown in Tables 2-5.

  From the results shown in Tables 2 to 5, in the polishing liquids of Examples 1 to 45, the polishing rate of the insulating film is high, and erosion and dishing are suppressed to be small.

Claims (9)

A polishing liquid used for chemical mechanical polishing in a semiconductor device manufacturing process, comprising colloidal silica particles, a benzotriazole compound represented by the following general formula (I), an oxidizing agent, and a divalent or higher valent ammonium cation And a chemical-mechanical polishing slurry containing a compound.

(In general formula (I), R ^{1 to} R ⁵ each independently represents a hydrogen atom, an unsubstituted or substituted alkyl group.) The polishing liquid for chemical mechanical polishing according to claim 1, wherein the divalent or higher ammonium cation compound is a compound represented by the following general formula (II).

(In General Formula (II), R ^{6 to} R ¹¹ each independently represent an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and among R ^{6 to} R ¹¹ , The two may be bonded to each other, and these may be further substituted with other functional groups such as an alkyl group, a hydroxyl group, an amino group, a carboxyl group, etc. X is an alkylene group having 1 to 30 carbon atoms, alkenylene. Group, a cycloalkylene group, an arylene group, or a linking group obtained by combining these groups, and this linking group may further have a substituent such as an alkyl group, a hydroxyl group, an amino group, a carboxyl group, (It may further contain a quaternary amine nitrogen. N represents an integer of 2 or more.)   The chemical mechanical polishing according to claim 1 or 2, wherein a content of the colloidal silica particles is in a range of 0.05 mass% to 15 mass% with respect to a total mass of the polishing liquid. Polishing fluid.   The polishing liquid for chemical mechanical polishing according to any one of claims 1 to 3, wherein the colloidal silica particles have a primary average particle diameter in a range of 5 nm to 100 nm.   5. The chemical mechanical polishing material according to claim 1, wherein the benzotriazole-based compound is selected from unsubstituted benzotriazole or a benzotriazole derivative having an alkyl substituent. 6. Polishing fluid.   Further, pectic acid, agar, polyvinyl alcohol, polyvinyl pyrrolidone, polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), 6. The water-soluble polymer according to claim 1, comprising at least one water-soluble polymer selected from polyacrylamide, polyacrylic acid, polyamic acid, polyacrylic acid sodium salt, and polyglyoxylic acid. A polishing liquid for chemical mechanical polishing described in 1.   Furthermore, it contains the at least 1 sort (s) of organic acid chosen from the compound group which has at least 1 carboxyl group in a molecule | numerator, The chemical mechanical as described in any one of Claims 1-6 characterized by the above-mentioned. Polishing liquid for polishing.   The polishing liquid for chemical mechanical polishing according to any one of claims 1 to 7, wherein the pH is 2 or more and 5 or less.   The polishing liquid for chemical mechanical polishing according to any one of claims 1 to 8, further comprising a nonionic surfactant or an anionic surfactant.