JP2008053371A - Polishing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing method of a semiconductor device, capable of continuously polishing a substrate containing an insulating film, a conductor film, and a barrier metal film with the same polishing solution, resulting in proper planarity of a surface to be polished after polishing, and is capable of reducing generation of scratches. <P>SOLUTION: The polishing method of a semiconductor device continuously polishes using a single polishing solution a barrier metal film formed over the entire surface of a substrate, having recesses or an interlayer insulating film and a conductive film made of copper or a copper alloy, formed on the surface of the barrier metal film, such that the recessed parts are embedded. In the polishing method, the polishing solution contains a barrier metal film polishing speed adjusting agent, represented by general Formula (I), amino acids, oxidants, and polishing particulates. In the Formula (I), R<SP>1</SP>represents H, CH<SB>3</SB>or NH<SB>2</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to manufacturing of semiconductor devices, and more particularly to a polishing method used for planarization in a wiring process of semiconductor devices.
In particular, the present invention relates to a polishing method applied to so-called one-step polishing in which copper conductor flattening CMP technology is used to polish a conductor film and a barrier metal film continuously with the same polishing liquid at a high polishing rate.

  In recent years, in the development of semiconductor devices typified by semiconductor integrated circuits (hereinafter referred to as “LSI” where appropriate), high-density and high-integration by miniaturization and stacking of wirings for miniaturization and high speed. Is required. For this purpose, various techniques such as chemical mechanical polishing (hereinafter, referred to as “CMP” as appropriate) have been used.

  A general method of CMP is to apply a polishing pad on a circular polishing platen (platen), immerse the surface of the polishing pad with a polishing liquid, press the surface of the substrate (wafer) against the pad, In a state where pressure (polishing pressure) is applied, both the polishing platen and the substrate are rotated, and the surface of the substrate is flattened by the generated mechanical friction.

  A metal polishing solution used in CMP generally contains abrasive grains (eg, alumina, silica) and an oxidizing agent (eg, hydrogen peroxide, persulfuric acid), and oxidizes the metal surface with the oxidizing agent. It is considered that the oxide film is polished by removing with an abrasive.

  However, when CMP is performed using a metal polishing liquid containing such solid abrasive grains, scratches (scratches), a phenomenon in which the entire polished surface is polished more than necessary (thinning), and the polished metal surface is flat In addition, a phenomenon in which only the center is polished deeper to form a dish-like depression (dishing), an insulator between metal wirings is polished more than necessary, and a plurality of wiring metal surface surfaces form dish-shaped recesses. A phenomenon (erosion) may occur.

  In order to solve such problems in the conventional solid abrasive grains, as a metal polishing liquid not containing abrasive grains, for example, for metals consisting of hydrogen peroxide / malic acid / benzotriazole / ammonium polyacrylate and water A polishing liquid and a polishing method are disclosed (for example, refer to Patent Document 1). According to the polishing method described in this document, the metal film on the convex portion of the semiconductor substrate is selectively CMPed, and the metal film is left in the concave portion to obtain a desired conductor pattern, but the conventional solid abrasive grains are included. Since CMP proceeds by friction with a much softer polishing pad than mechanically, there is a problem that it is difficult to obtain a sufficient polishing rate.

  Further, an aqueous dispersion for chemical mechanical polishing containing an organic compound that suppresses deterioration of the polishing pad is disclosed (for example, see Patent Document 2). However, even with this polishing aqueous dispersion, there is concern about the dishing phenomenon in which the wiring portion metal is excessively polished and recessed on the dish.

  In recent years, in order to improve productivity, the diameter of a wafer at the time of manufacturing an LSI has been increased. Currently, a diameter of 200 mm or more is widely used, and manufacturing with a size of 300 mm or more has started. As the size of the wafer increases, a difference in polishing rate between the central portion of the wafer and the peripheral portion tends to occur, and it is important to achieve polishing uniformity.

  On the other hand, as a chemical polishing method having no mechanical polishing means for copper and copper alloys, a method using a chemical dissolution action is known (for example, see Patent Document 3). However, the chemical polishing method using only the chemical dissolution action is more flat than the CMP in which the metal film of the convex portion is selectively chemically and mechanically polished due to the occurrence of dishing of the concave portion, that is, dishing. Big challenges remain.

  Further, when copper wiring is used, a diffusion preventing layer called a barrier layer is generally provided between the wiring portion and the insulating layer in order to prevent copper ions from diffusing into the insulating material. This barrier layer is composed of one or more layers including one selected from alloys such as TaN, TaSiN, Ta, TiN, Ti, Ru, Nb, W, WN, Co, Zr, ZrN, and CuTa. It is composed of a metal film (barrier metal film). However, since these barrier layer materials themselves have conductive properties, the barrier layer material on the insulating layer must be completely removed to prevent the occurrence of errors such as leakage current. This is achieved by a method similar to the bulk polishing of the wiring material (this method is sometimes referred to as “barrier CMP”).

  At present, the polishing film for metal with a polishing rate for the conductor film is higher than the polishing rate for the barrier metal film, the conductor film is polished using the barrier metal film as a stop layer, and then a different metal polishing liquid is used. Thus, a two-step process of polishing the conductor film and the barrier metal film is used. In accordance with this, the optimum process consumable member for each metal polishing liquid is different, and therefore polishing is performed using a plurality of pads.

However, when the plurality of pads are used, there are many problems such as that process consumable members corresponding to each of the pads are necessary and costly, and that the manufacturing process is complicated and the total processing time is delayed. . Therefore, in order to solve these problems, it is conceivable to perform polishing with one pad. However, in order to polish a wafer using a plurality of polishing liquids with one pad, there is a problem that it takes a lot of time and labor depending on the time required for exchanging and preparing the metal polishing liquid and cleaning the pad. A point is mentioned.
Therefore, a process (hereinafter referred to as “one-step process”) in which a substrate having an insulating film (interlayer insulating film), a barrier metal film, and a conductor film is continuously polished with the same metal polishing liquid. .)

  If a one-step process is realized, it is possible to speed up the polishing time associated with the reduction in the frequency of replacement of the metal polishing liquid, increase the production efficiency of the semiconductor device manufacturing line, and further require a plurality of polishing apparatuses. In addition to this, many practical merits such as downsizing of the apparatus can be expected. In addition, in the current polishing method, since the waste liquid after polishing is in a state where two types of slurry are mixed, it is difficult to process, whereas in one step process, there is one type of slurry. It becomes simple and can contribute to reduction of environmental load.

In order to realize the one-step process, it is necessary to match the polishing rate ratios in the conductor film, the barrier metal film, and the insulating film (hereinafter, appropriately referred to as “selection ratio”) as much as possible.
Furthermore, the obstacle to the realization of a one-step metal polishing liquid is that when the conductor film and the barrier metal film are polished continuously, there is no layer that stops polishing, so-called stopper layer. . As a result, scratches occur, and problems such as deterioration in flatness between the wiring part and the insulating film convex part occur.
Thus, regarding the realization of the one-step process in CMP, no effective technique has been provided yet.
JP 2001-127019 A JP 2001-279231 A JP 49-122432 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, an object of the present invention is to be able to continuously polish a substrate having an insulating film, a conductor film and a barrier metal film with the same polishing liquid, and the flatness of the polished surface after polishing is good. Another object of the present invention is to provide a semiconductor device polishing method capable of reducing the occurrence of scratches.

  As a result of diligent investigations on problems in the polishing liquid used in the one-step process, the present inventor has polished a solution system containing an oxidizing agent, a specific amino acid and abrasive particles, and a barrier metal film polishing rate regulator added. By using the liquid, the conductor film and the barrier metal film can be continuously polished with the same polishing liquid, and the insulating film can function as a stop layer (stopper layer), and the present invention is completed. It came to.

  That is, the means for solving the problems are as follows.

<1> A barrier metal film formed on the entire surface of a substrate having a recess or an interlayer insulating film, and a conductor film made of copper or a copper alloy formed so that the recess is buried in the surface of the barrier metal film. A method for polishing a semiconductor device in which polishing is continuously performed with one polishing liquid, wherein the polishing liquid contains a barrier metal film polishing rate adjusting agent represented by the following general formula (I), an amino acid, an oxidizing agent, and polishing particles A method for polishing a semiconductor device, comprising:

In general formula (I), R ¹ represents H, CH ₃ , or NH ₂ .

<2> The polishing method according to claim 1, wherein a molar ratio of the polishing rate adjusting agent and the amino acid is (polishing rate adjusting agent) :( amino acid) = 3: 1 to 8: 1. .
The polishing method according to <1>, wherein the amino acid is at least one selected from compounds represented by the following general formula (II).
<3> The polishing method according to <1> or <2>, wherein the amino acid is a compound represented by the following general formula (II).

In general formula (II), R ² represents a single bond, an alkylene group, or a phenylene group, and R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group. Represents a group, an alkynyl group, or an aryl group, and R ⁵ and R ⁶ each independently represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or an acyl group. However, when R ² is a single bond, at least one of R ⁵ and R ⁶ is not a hydrogen atom. ]
The polishing according to <1> or <2>, wherein a molar ratio of the polishing rate adjusting agent and the amino acid is (polishing rate adjusting agent) :( amino acid) = 3: 1 to 8: 1. Method.

<4> The polishing method according to any one of <1> to <3>, wherein the oxidizing agent is a hydrogen peroxide solution.
<5> The polishing method according to any one of <1> to <4>, wherein the polishing liquid has a pH of 5 to 8.
<6> The polishing method according to any one of <1> to <5>, wherein the abrasive particles are silica particles.

  According to the present invention, a substrate having a conductor film and a barrier metal film can be continuously polished with the same polishing liquid, the flatness of the polished surface after polishing is good, and the scratch It is possible to provide a semiconductor device polishing method capable of reducing generation.

  A polishing method for a semiconductor device according to the present invention includes a barrier metal film formed on the entire surface of a substrate having a recess or an interlayer insulating film, and copper or copper formed so that the recess is buried in the surface of the barrier metal film. A semiconductor device polishing method for continuously polishing a conductor film made of an alloy with a single polishing liquid, wherein the polishing liquid is a barrier metal film polishing rate modifier represented by the following general formula (I), an amino acid, A polishing method for a semiconductor device comprising an oxidizing agent and abrasive particles.

In general formula (I), R ¹ represents H, CH ₃ , or NH ₂ .

First, the polishing liquid suitably used in the polishing method of the present invention will be described, and then the polishing method of the present invention will be described, but the present invention is not limited thereto.
[Polishing liquid]
The polishing liquid in the present invention comprises component (1) a barrier metal film polishing rate adjusting agent represented by the following general formula (I), component (2) amino acid, component (3) oxidizing agent, and component (4) abrasive particles. And including.

In general formula (I), R ¹ represents H, CH ₃ , or NH ₂ .

The polishing liquid in the present invention contains the components (1) to (4) as essential components. Usually, it contains water. The polishing liquid in the present invention may further contain other components as desired. Other preferable components include additives such as compounds added as so-called passive film forming agents (heterocyclic compounds, etc.), surfactants and / or hydrophilic polymers, acids, alkalis, buffers, and the like. it can.
Each of the above components (essential components and optional components) contained in the polishing liquid may be used alone or in combination of two or more.

  In the present invention, the “polishing liquid” includes not only a polishing liquid used for polishing but also a concentrated liquid of the polishing liquid. The concentrated liquid is diluted with water or an aqueous solution when used for polishing and used for polishing, and the dilution ratio is generally 1 to 20 times volume.

Hereinafter, each component will be described.
<Component (1): Polishing rate adjusting agent>
The polishing liquid in the present invention is represented by the following general formula (I) and contains a barrier metal film polishing rate adjusting agent. By containing the compound represented by the following general formula (I) in the polishing liquid in the present invention, only the polishing rate of Ta formed on the entire surface of the substrate having a recess or the interlayer insulating film is improved, and the conductor film And the selectivity of the barrier metal film (conductor film / barrier metal film) can be optimized.

In general formula (I), R ¹ represents H, CH ₃ , or NH ₂ .

  Examples of the polishing rate adjusting agent include methylsulfonic acid, ethylsulfonic acid, and aminomethanesulfonic acid represented by the general formula (I). Above all, from the viewpoint of maintaining the polishing rate selection ratio between the conductor film and the insulating film (conductor film / insulating film) and reducing the polishing rate selection ratio between the conductor film and the barrier metal film (conductor film / barrier metal film). Aminomethanesulfonic acid is particularly desirable.

  There is no restriction | limiting in particular as a synthesis method of the compound represented by general formula (I), It can synthesize | combine by a well-known method. A commercially available compound may be used as the compound represented by the general formula (I).

  When the component (1) in the present invention is not added, the selection ratio of the polishing rate between the barrier metal film and the conductor film (hereinafter appropriately referred to as “selection ratio”) is (conductor film / barrier metal film) = 400 to About 500. On the other hand, when the polishing rate adjusting agent in the present invention is added to the polishing liquid in a range of 0.030 mol to 0.508 mol per liter of the polishing liquid, the selection ratio is 10 to 100. Moreover, it will become a more preferable aspect if the density | concentration of a polishing-rate regulator is optimized. That is, when the polishing rate adjusting agent is added to the polishing liquid in a range of 0.127 mol to 0.254 mol per liter of the polishing liquid, the selection ratio is 10 to 20. As a more preferred embodiment, the polishing rate adjusting agent is added to the polishing liquid in a range of 0.127 mol to 0.254 mol per liter of the polishing liquid, and the amino acid of the component (2) is represented by the following general formula (II). When the compound is added to the polishing liquid, the selectivity is 10-18.

<Component (2): Amino acid>
The polishing liquid in the present invention contains an amino acid that exhibits the action of promoting oxidation, adjusting pH, and buffering agent. The amino acids are described in detail below.

As the amino acid, one selected from the following group is more suitable.
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-cysteine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-cystine, L-cystine acid, L -Aspartic acid, L-glutamic acid, S- (carboxymethyl) -L-cysteine, 4-aminobutyric acid, Asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-quinurenin, L-histidine, 1-methyl-L-histidine, 3-methyl -Amino acids such as L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipine.

  In the present invention, among the amino acids, it is particularly preferable to use a compound represented by the following general formula (II). By adding the compound represented by the following general formula (II) and the compound represented by the above general formula (I) to the polishing liquid in the present invention, the selectivity between the conductor film and the barrier metal film (conductor film / Barrier metal film) is optimized. Below, the compound represented by general formula (II) is demonstrated.

  The structure of the specific amino acid can be represented by the following general formula (II).

R ² represents a single bond, an alkylene group, or a phenylene group.
R ³ and R ⁴ each independently represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group.
R ⁵ and R ⁶ each independently represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or an acyl group.
However, when R ² is a single bond, at least one of R ⁵ and R ⁶ is not a hydrogen atom.

The alkylene group as R ² in the general formula (II) may be linear, branched or cyclic, and preferably has 1 to 8 carbon atoms, and examples thereof include a methylene group and an ethylene group. Can do. Examples of the substituent that the alkylene group may have include a hydroxyl group and a halogen atom.

The alkyl group as R ³ and R ⁴ in the general formula (II) preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group.
The cycloalkyl group as R ³ and R ⁴ in the general formula (II) preferably has 5 to 15 carbon atoms, and examples thereof include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.
The alkenyl group as R ³ and R ⁴ in the general formula (II) preferably has 2 to 9 carbon atoms, and examples thereof include a vinyl group, a propenyl group, and an allyl group.
The alkynyl group as R ³ and R ⁴ in the general formula (II) preferably has 2 to 9 carbon atoms, and examples thereof include an ethynyl group, a propynyl group, and a butynyl group.

The aryl group as R ³ and R ⁴ in the general formula (II) preferably has 6 to 15 carbon atoms, and examples thereof include a phenyl group.
The alkylene chain in these groups may have a hetero atom such as an oxygen atom or a sulfur atom.
Examples of the substituent that each group as R ³ and R ⁴ in the general formula (II) may have include a hydroxyl group, a halogen atom, an aromatic ring (preferably having 3 to 15 carbon atoms), a carboxyl group, an amino group, and the like. Can be mentioned.

The alkyl group as R ⁵ and R ⁶ in the general formula (II) preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and an ethyl group.
The acyl group preferably has 2 to 9 carbon atoms, and examples thereof include a methylcarbonyl group.
Examples of the substituent that each group represented by R ⁵ and R ⁶ in the general formula (II) may have include a hydroxyl group, an amino group, and a halogen atom.
In general formula (II), it is preferable that either one of R ⁵ and R ⁶ is not a hydrogen atom.

In the general formula (II), it is particularly preferable that R ² is a single bond, and R ³ and R ⁵ are hydrogen atoms. In this case, R ⁴ represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group, and particularly preferably a hydrogen atom or an alkyl group. R ⁶ represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group or an acyl group, and particularly preferably an alkyl group. As the substituent that the alkyl group as R ³ may have, a hydroxyl group, a carboxyl group, or an amino group is preferable. As the substituent that the alkyl group as R ⁵ may have, a hydroxyl group or an amino group is preferable.

  Although the specific example of a compound represented by general formula (II) below is shown, it is not limited to these.

  There is no restriction | limiting in particular as a synthesis method of the compound represented by general formula (II), It can synthesize | combine by a well-known method. A commercially available compound may be used as the compound represented by the general formula (II).

  The content ratio of amino acids in the present invention is a molar ratio with the polishing rate adjusting agent in order to optimize the selection ratio (conductor film / barrier metal film) between the conductor film and the barrier metal film. = 3: 1 to 8: 1 is preferable, and 4: 1 to 5: 1 is more preferable.

<Component (3): Oxidizing agent>
The polishing liquid in the present invention contains an oxidizing agent (a compound capable of oxidizing 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. 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.

  Among the oxidizing agents, hydrogen peroxide, persulfate, and iron (III) ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′, N A complex of '-tetraacetic acid and ethylenediamine disuccinic acid (SS form) is most preferred.

  The addition amount of the oxidizing agent is preferably in the range of 0.003 to 8 mol / L, more preferably in the range of 0.03 to 6 mol / L, with respect to the polishing liquid. A range of 5 mol / L is particularly preferable. That is, the addition amount of the oxidizing agent is preferably 0.003 mol / L or more from the viewpoint of sufficient metal oxidation and ensuring a high CMP rate, and 8 mol / L or less from the viewpoint of preventing the polishing surface from being rough. Preferably there is.

  The oxidizing agent is preferably used by mixing with a composition containing other components other than the oxidizing agent when polishing using a polishing liquid. The timing of mixing the oxidizing agent is preferably within 1 hour immediately before using the polishing liquid, more preferably within 5 minutes, and particularly preferably, a mixer is provided immediately before the polishing liquid is supplied by the polishing apparatus. Mixing within 5 seconds immediately before feeding to the polishing surface.

<Component (4): Abrasive particles>
The polishing liquid in the present invention contains abrasive particles (abrasive grains).
The abrasive particles may be any of inorganic particles such as silica, alumina, ceria, titania, zirconia, germania, and silicon carbide, and organic particles such as polystyrene, polyacryl, and polyvinyl chloride. Among these, at least one kind of particles selected from silica, alumina, ceria, titania, zirconia, and germania is preferable, and dispersion stability in the polishing liquid is good, and generation of polishing scratches (scratches) generated by CMP. A small number of silica particles (precipitated silica, fumed silica, colloidal silica, synthetic silica) is preferred. The silica particles are preferably colloidal silica or fumed silica, and more preferably colloidal silica because of the high polishing rate for copper-containing metals.

  In addition, the abrasive particles contained in the polishing liquid in the present invention are particles having a volume average particle diameter determined by a dynamic light scattering method in the range of 25 to 70 nm.

  The volume average particle diameter of the particles is determined by a dynamic light scattering method. Specifically, it can measure using the particle size distribution measuring apparatus (Horiba Ltd. make, LB-500) which employ | adopted the dynamic light-scattering method.

  The colloidal silica can be obtained by a well-known production method. As a wet manufacturing method of metal oxide particles, colloidal particles are obtained by, for example, a method of hydrolyzing metal alkoxide as a starting material. Specifically, orthosilicic acid is added to an alkaline aqueous solution mixed with alcohol. Colloidal silica can be produced by dropping methyl at a certain rate to cause hydrolysis and undergoing grain growth and quenching to stop grain growth. In addition, colloidal particles are made using alkoxides such as aluminum and titanium. In this case, the rate of hydrolysis is generally faster than when silicon alkoxide is used, which is convenient when producing ultrafine particles.

  Further, as a dry manufacturing method of metal oxide, fumed particles can be obtained by a reaction in which a metal chloride is introduced into an oxyhydrogen flame and the dechlorinated metal is oxidized. Furthermore, the metal or alloy to be contained in the target substance is pulverized into powder, and this is put into an oxygen flame containing a combustion-supporting gas, causing a continuous reaction by the oxidation heat of the metal, and fine A method for obtaining oxide particles has been put into practical use. Particles produced by these combustion methods are amorphized because they are rapidly cooled after being exposed to high heat, and the solid density is generally low because there are fewer impurities such as hydroxyl groups inside than wet particles. It is characterized by high density and low density of hydroxyl groups on the surface.

  The addition amount of the abrasive particles is preferably in the range of 0.0001 to 5 mass%, more preferably in the range of 0.1 to 2.0 mass% with respect to the polishing liquid used. In order to obtain a sufficient effect for improving the polishing rate and reducing variations in the polishing rate within the wafer surface, 0.0001% by mass or more is preferable, and since the polishing rate by CMP is saturated, 5% by mass or less is preferable.

<PH of polishing liquid>
The pH of the polishing liquid in the present invention is 2 or more, preferably in the range of pH 2 to 10, more preferably in the range of pH 5 to 8. Within this range, the polishing liquid in the present invention exhibits particularly excellent effects. In the polishing, the polishing liquid in the present invention may be in a form not containing water, or may be diluted with water or an aqueous solution. When diluted with water or an aqueous solution, the pH in the present invention represents a value after dilution with water or an aqueous solution.
The pH of the polishing liquid in the present invention takes into consideration the adsorptivity and reactivity to the polishing surface, the solubility of the polishing metal, the electrochemical properties of the surface to be polished, the dissociation state of the compound functional group, the stability as the liquid, etc. Can be set.
The pH can be adjusted, for example, by adding an alkali agent described later, and by adding an acid other than the component (2), a buffering agent, or the like.

<Other ingredients>
-Heterocyclic compounds-
The polishing liquid in the present invention preferably contains a heterocyclic compound as a compound that forms a passive film on the metal surface to be polished.
A “heterocyclic compound” is a compound having a heterocycle containing a heteroatom.
The number of heteroatoms contained in the compound having a heterocycle is not limited, but is preferably 2 or more, more preferably 4 or more heteroatoms. In particular, it is preferable to use a heterocyclic compound containing 3 or more nitrogen atoms, and using a heterocyclic compound containing 4 or more nitrogen atoms is preferable because the remarkable effects of the present invention can be obtained.
Further, the heterocyclic ring may be a single ring or a polycyclic ring having a condensed ring. The number of members in the case of a single ring is preferably 5 to 7, particularly preferably 5. In the case of having a condensed ring, the number of rings is preferably 2 or 3.

Specific examples of these heterocyclic rings include the following.
Pyrrole ring, thiophene ring, furan ring, pyran ring, thiopyran ring, imidazole ring, pyrazole ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, pyrrolidine ring, Pyrazolidine ring, imidazolidine ring, isoxazolidine ring, isothiazolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, chroman ring, thiochroman ring, isochroman ring, isothiochroman ring, indoline ring, isoindoline ring, pyringin Ring, indolizine ring, indole ring, indazole ring, purine ring, quinolidine ring, isoquinoline ring, quinoline ring, naphthyridine ring, phthalazine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine Perimidine ring, phenanthroline ring, carbazole ring, carboline ring, phenazine ring, anti-lysine ring, thiadiazole ring, oxadiazole ring, triazine ring, triazole ring, tetrazole ring, benzimidazole ring, benzoxazole ring, benzthiazole ring, benz A thiadiazole ring, a benzfuroxan ring, a naphthimidazole ring, a benztriazole ring, a tetraazaindene ring and the like are mentioned, and a triazole ring and a tetrazole ring are more preferred.
Examples of the substituent that can be introduced into the heterocyclic compound used in the present invention include the following.
Examples of the substituent that the heterocyclic ring may have include, for example, a halogen atom, an alkyl group (a linear, branched or cyclic alkyl group, and an active methine group, even a polycyclic alkyl group such as a bicycloalkyl group). Or an alkenyl group, an alkynyl group, an aryl group, an amino group, or a heterocyclic group. Furthermore, two or more of a plurality of substituents may be bonded to each other to form a ring, and for example, an aromatic ring, an aliphatic hydrocarbon ring, a heterocyclic ring, or the like can be formed.

Specific examples of the heterocyclic compound that can be particularly preferably used in the present invention include, but are not limited to, the following.
That is, 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1,2,3-triazole, 4- Amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino- 1,2,4-triazole and benzotriazole.
The heterocyclic compounds used in the present invention may be used alone or in combination of two or more. Moreover, the heterocyclic compound used by this invention can be synthesize | combined according to a conventional method, and may use a commercial item.

  The total amount of the heterocyclic compound used in the present invention is 0.0001 to 1.0 mol in 1 L of a polishing liquid used for polishing (that is, a diluted polishing liquid when diluted with water or an aqueous solution). Is more preferable, more preferably in the range of 0.0005 to 0.5 mol, and still more preferably in the range of 0.0005 to 0.05 mol.

-Surfactant and / or hydrophilic polymer-
The polishing liquid used in the present invention preferably contains a surfactant or a hydrophilic polymer.
Both the surfactant and the hydrophilic polymer have the action of reducing the contact angle of the surface to be polished and the action of promoting uniform polishing. As the surfactant and the hydrophilic polymer used, those selected from the following groups are suitable.
Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. Examples of the cationic surfactant include aliphatic amine salt, aliphatic quaternary ammonium salt, benzalkonium chloride. Salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and amphoteric surfactants include carboxybetaine type, aminocarboxylate, imidazolinium betaine, lecithin, alkylamine oxide, nonionic interface Examples of the activator include an ether type, an ether ester type, an ester type, and a nitrogen-containing type, and also include a fluorine-based surfactant.
Furthermore, examples of the hydrophilic polymer include polyglycols such as polyethylene glycol, polysaccharides such as polyvinyl alcohol, polovinyl pyrrolidone, and alginic acid, and carboxylic acid-containing polymers such as polymethacrylic acid.

  Of the above, the acid or its ammonium salt is preferably free from contamination by alkali metals, alkaline earth metals, halides and the like. Among the above exemplified compounds, cyclohexanol, polyacrylic acid ammonium salt, polyvinyl alcohol, succinic acid amide, polo vinyl pyrrolidone, polyethylene glycol, and polyoxyethylene polyoxypropylene block polymer are more preferable.

  The weight average molecular weight of these surfactants and hydrophilic polymers is preferably from 500 to 100,000, particularly preferably from 2,000 to 50,000.

  The total amount of the surfactant and / or hydrophilic polymer added is preferably 0.001 to 10 g and preferably 0.01 to 5 g in 1 liter of the metal polishing slurry used for polishing. Is more preferably 0.1 to 3 g.

-Chelating agents, alkalis, buffering agents-
In the present invention, it is preferable to further add a chelating agent, an alkali, and a buffer. Below, the chelating agent, alkali, and buffering agent which can be used for this invention are demonstrated.

(Chelating agent)
The polishing liquid in 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 so that it is in the range.

(Alkaline agent, buffer agent)
Moreover, the polishing liquid in the present invention can contain an alkali agent for pH adjustment and further a buffering agent from the viewpoint of suppressing fluctuations in pH, if necessary.

  Alkaline agents and buffering agents include organic ammonium hydroxides such as ammonium hydroxide and tetramethylammonium hydroxide, nonmetallic alkali agents such as alkanolamines such as diethanolamine, triethanolamine, triisopropanolamine, and the like. Alkali metal hydroxides such as sodium, potassium hydroxide and lithium hydroxide, carbonate, phosphate, borate, tetraborate, hydroxybenzoate, glycyl salt, N, N-dimethylglycine salt, leucine Salt, norleucine salt, guanine salt, 3,4-dihydroxyphenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydroxyaminomethane salt Lysine salt etc. can be used .

Specific examples of alkaline agents and buffering agents include ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, phosphorus Disodium acid, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, sodium o-hydroxybenzoate (sodium salicylate), potassium o-hydroxybenzoate, 5 -Sodium sulfo-2-hydroxybenzoate (sodium 5-sulfosalicylate), potassium 5-sulfo-2-hydroxybenzoate (potassium 5-sulfosalicylate), ammonium hydroxide and the like.
Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkali agent and the buffer may be an amount that can maintain the pH within a preferable range, and may be in the range of 0.0001 mol to 1.0 mol in 1 L of the polishing liquid used for polishing. Preferably, the range is 0.003 mol to 0.5 mol.

  In the present invention, the specific gravity of the polishing liquid is preferably in the range of 0.8 to 1.5 from the viewpoint of the fluidity of the liquid and the stability of the polishing performance, and the range of 0.95 to 1.35. It is particularly preferable to do this.

[Polishing method]
The polishing method of the present invention comprises a barrier metal film having a recess and formed on the entire surface of a substrate or an interlayer insulating film, and copper and / or copper formed so that the recess is buried in the surface of the barrier metal film. A method of polishing a conductor film made of an alloy using the surface on the conductor film side as a surface to be polished, wherein the polishing film is continuously polished with one polishing liquid.

  That is, in the polishing method of the present invention, the conductive film formed on the surface other than the concave portion of the insulating film with a single type of polishing liquid is chemically and mechanically polished, and then continuously with the same polishing liquid. In particular, a chemical mechanical polishing method using a polishing liquid capable of polishing the residual film of the conductor film and the barrier metal film, and the polishing liquid according to the present invention is used as the polishing liquid.

  The polishing liquid used in the polishing method of the present invention is a concentrated liquid and when used to dilute by adding water, or each component is mixed in the form of an aqueous solution described later, If necessary, it may be diluted with water to make a working solution, or it may be prepared as a working solution. The polishing liquid in the present invention is not particularly limited, but any of the above aspects can be applied in the present invention.

  In the polishing method of the present invention, a polishing liquid is supplied to a polishing pad on a polishing surface plate, 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 (moved relatively) for polishing. Polishing method.

  As a polishing apparatus, a general polishing apparatus having a polishing surface plate (with a motor or the like capable of changing the number of rotations) attached with a holder for holding a semiconductor substrate having a surface to be polished and a polishing pad. Can be used.

  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 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. The latter is further divided into three types: an independent foam (dry foam system), a continuous foam (wet foam system), and a two-layer composite (laminate system), and a two-layer composite (laminate system) is particularly preferable. Foaming may be uniform or non-uniform.

Further, the polishing pad may contain particles (for example, ceria, silica, alumina, resin, etc.) used for polishing.
In addition, each of the polishing pads may be soft or hard, and either may be used. In the laminated system, it is preferable to use a different hardness for each layer. The material is preferably non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate or the like. In addition, the surface contacting the polishing surface may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

The polishing conditions are not limited, but the linear velocity of the polishing platen is preferably 1 m / s or more.
The pressure (pressing pressure) when a semiconductor substrate having a surface to be polished (film to be polished) is pressed against the polishing pad is preferably 20 kPa or less, and further, under a low pressure condition of 13 kPa or less, a high polishing rate. This is more preferable because it is possible to improve the uniformity of the polishing rate within the wafer surface and the flatness of the pattern while maintaining the above.
In addition, when pressing pressure exceeds 20 kPa, flatness may deteriorate.
The lower limit of the pressing pressure is not particularly limited, but is preferably 2 kPa or more, and more preferably 3.5 kPa or more.

  During polishing, a polishing liquid is continuously supplied to the polishing pad with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid. The semiconductor substrate after polishing is thoroughly washed in running water, and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like.

  In the polishing method of the present invention, the aqueous solution for diluting the polishing liquid is the same as the aqueous solution described below. The aqueous solution is water containing at least one of an oxidizing agent, an acid, an additive, and a surfactant, and a component obtained by adding up the components contained in the aqueous solution and the components of the polishing liquid to be diluted is a polishing liquid. It becomes a component when polishing using. When the polishing liquid is diluted with an aqueous solution and used, components that are difficult to dissolve can be blended in the form of an aqueous solution, and a more concentrated polishing liquid can be prepared.

  As a method of diluting the concentrated polishing 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 joined together and mixed, and mixed and diluted. There is a method of supplying a polishing pad to a polishing pad. Mixing is a method in which liquids collide with each other through a narrow passage under pressure, a method in which a filling such as a glass tube is filled in the pipe, and the flow of liquid is repeatedly separated and merged. Conventional methods such as a method of providing blades that rotate in the above can be employed.

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

  As a method of diluting and polishing the concentrated polishing liquid with water or an aqueous solution, a pipe for supplying the polishing liquid and a pipe for supplying water or an aqueous solution are provided independently, and a predetermined amount of liquid is supplied from each to the polishing pad. Further, there is a method of polishing while mixing by a relative motion of the polishing pad and the surface to be polished. Alternatively, it is also possible to apply a method in which a predetermined amount of a concentrated polishing liquid and water or an aqueous solution are mixed in one container and then the mixed polishing liquid is supplied to a polishing pad for polishing.

  In the present invention, the component to be contained in the polishing liquid is divided into at least two components, and when these are used, they are diluted by adding water or an aqueous solution and supplied to the polishing pad on the polishing platen, It is also possible to use a method in which the surface to be polished and the polishing pad are moved relative to each other in contact with the surface for polishing.

For example, an oxidant is one component (A), an additive, a surfactant and water are one component (B), and when they are used, the component (A) and the component in water or an aqueous solution are used. Dilute (B) for use.
In addition, the low-solubility additive is divided into two components (C) and (D), and the oxidizing agent, additive, and surfactant are one component (C), and the acid, additive, and surfactant And water as one component (D), and when using them, water or an aqueous solution is added to dilute the component (C) and the component (D).

In the case of this example, three pipes for supplying the component (C), the component (D), and water or an aqueous solution are required, and dilution mixing is performed on one pipe that supplies the three pads to the polishing pad. There is a method of combining and mixing in the pipe. In this case, it is also possible to combine two pipes and then connect another pipe.
For example, a constituent component containing an additive that is difficult to dissolve is mixed with another constituent component, a mixing path is lengthened to secure a dissolution time, and then a pipe for water or an aqueous solution is further combined.

  Other mixing methods are as described above, in which the three pipes are each guided directly to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished, and the three components are mixed in one container. And a method of supplying a diluted polishing liquid to the polishing pad. In the above polishing method, one constituent component containing an oxidizing agent is made 40 ° C. or lower, the other constituent components are heated in the range of room temperature to 100 ° C., and one constituent component and another constituent component or water or an aqueous solution When the mixture is diluted and used, it can be adjusted to 40 ° C. or lower after mixing. Since the solubility increases when the temperature is high, this is a preferable method for increasing the solubility of the raw material having a low solubility of the polishing liquid.

  A raw material in which other components not containing an oxidizing agent are heated and dissolved in the range of room temperature to 100 ° C. is precipitated in the solution when the temperature is lowered. It is necessary to dissolve what is deposited by heating. For this, a means for feeding a heated component solution and a means for stirring the liquid containing the precipitate, feeding the liquid, and heating and dissolving the pipe can be employed. When the temperature of one component containing an oxidant is increased to 40 ° C. or higher, the oxidant may be decomposed. Therefore, the heated component and the oxidation for cooling the heated component When mixed with one component containing an agent, the temperature is set to 40 ° C. or lower.

  In the present invention, as described above, the components of the polishing liquid may be divided into two or more parts and supplied to the polishing surface. In this case, it is preferable to divide and supply the component containing an oxide and the component containing an acid. Alternatively, the polishing liquid may be a concentrated liquid, and diluted water may be separately supplied to the polishing surface.

  As described above, when supplying the polishing liquid by dividing the components of the polishing liquid into two or more parts and supplying them to the polishing surface, the polishing liquid is used as a concentrate and the dilution water is separated from the polishing surface. A distinction is made when supplying. However, in any polishing liquid supply method, in the polishing method of the present invention, the conductive film formed on the convex portion of the insulating film is chemically mechanically polished with one type of polishing liquid, and then the same method is used. It is possible to polish the remaining film of the conductor film and the barrier metal film continuously with the polishing liquid.

  An object to be polished by the polishing method of the present invention includes a barrier metal film formed on the entire surface of an interlayer insulating film having a recess, and copper and / or copper formed so that the recess is buried in the surface of the barrier metal film. Or a conductor film made of a copper alloy, which is a semiconductor substrate, preferably an LSI having wiring made of copper metal and / or copper alloy, and the wiring is particularly a copper alloy. It is preferable.

  Furthermore, the copper alloy containing silver is preferable among copper alloys. The silver content contained in the copper alloy is preferably 40% by mass or less, more preferably 10% by mass or less, still 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.

  In the present invention, the semiconductor substrate to be polished is preferably 0.15 μm or less, more preferably 0.10 μm or less, and further preferably 0.08 μm or less in a half pitch in a DRAM device system, for example. On the other hand, in the MPU device system, 0.12 μm or less is preferable, 0.09 μm or less is more preferable, and an LSI having a wiring of 0.07 μm or less is more preferable. By using the polishing liquid of the present invention for these LSIs, particularly excellent effects are exhibited.

(substrate)
Examples of the substrate used in the present invention include those used in 8-inch and 12-inch semiconductor wafer manufacturing processes or micromachine manufacturing processes. The types include compound semiconductor sapphire substrates used for semiconductor silicon wafers, SOI wafers, semiconductor lasers, and the like. In addition, it is used for the purpose of flattening by forming a wiring pattern on a polymer film substrate.
The target wafer to be subjected to CMP with the polishing liquid in the present invention 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.

(Interlayer insulation film)
The polishing method of the present invention can be used not only for planarizing wiring on a substrate but also for planarizing a multilayer wiring substrate. In this case, the wiring formed on the interlayer insulating film can be planarized. The interlayer insulating film in the present invention is a film for insulating between layers formed between the substrate (wafer) and a barrier metal layer described later.
The interlayer insulating film in the present invention is not particularly limited as long as it is an insulating film formed on the substrate, but a silica-based film or an organic film effectively exhibits the effects of the present invention. In particular, a silica-based film is preferable. Examples of the silica-based coating include a silica-based coating doped with carbon, fluorinated silicon glass, hydrogen silsesquioxane, methyl silsesquioxane, and the like, but a silica-based coating doped with carbon is preferable.
The content of carbon in the silica-based film doped with carbon is preferably 20% by mass to 60% by mass from the viewpoint of reducing the effective dielectric constant and maintaining the mechanical strength of the insulating film itself. 35% by mass is particularly preferred.
Examples of the organic coating include polyimide, parylene, and Teflon (registered trademark), and polyimide is preferable.
In addition, it is preferable that the dielectric constant of the interlayer insulating film has a characteristic of 2.6 or less from the viewpoint that the effect of the present invention can be effectively obtained, and it is more preferable that it is 2.4 to 2.5. .
The interlayer insulating film in the present invention is more preferably a combination of the above preferred examples.
In addition, the thickness of the interlayer insulating film in the present invention can be appropriately adjusted depending on the upper and lower portions of the wiring in the multilayer wiring or between generations (nodes).
The method for forming an interlayer insulating film according to the present invention is described in US Pat. Nos. 6,440,866, 6,410,463, 6,596,654 and the like. Can be mentioned.

(Barrier metal film)
The barrier metal film is a film (layer) for preventing diffusion of copper between a conductor film (wiring) made of copper and / or a copper alloy provided on a semiconductor substrate and an interlayer insulating film.
The material of the barrier metal film is preferably a low-resistance metal material, and specifically includes at least one selected from tantalum or a tantalum compound, titanium or a titanium compound, tungsten or a tungsten compound, and ruthenium. It is more preferable that TiN, TiW, Ta, TaN, W, WN, and Ru are included, and Ta and TaN are particularly preferable.
The thickness of the barrier metal film is preferably about 5 to 30 nm.

  As described above, by polishing a semiconductor device with the polishing method of the present invention, a substrate having an insulating film, a conductor film, and a barrier metal film can be continuously polished with the same polishing liquid, The flatness of the polished surface after polishing is good, and the generation of scratches can be reduced.

  Hereinafter, the present invention will be described specifically by way of examples. The present invention is not limited to these examples.

<Preparation of abrasive grains>
Colloidal silica was prepared using a general synthesis method of colloidal silica obtained from hydrolysis of alkoxysilane. That is, a mixture of normal methyl silicate and an organic solvent was dropped into a solution in which methanol, ammonia, pure water and a dispersant were mixed with stirring at a constant temperature of 50 ° C. or higher to prepare abrasive grains.
In addition, the particle diameter control of the particle | grains of the following component (4) was controlled by adjusting the stirring speed of particle | grains. Thereafter, the abrasive (4) was quenched by adding a large amount of methanol after the reaction was produced, and was replaced with an aqueous solvent by an evaporator as necessary to complete the preparation of the component (4) particles.

  The abrasive grains prepared as described above are colloidal silica manufactured by Fuso Chemical Co., Ltd. as the component (4) particles, and trade names: PL-7 (volume average particle diameter: 70 nm), PL-10 (volume average particle diameter). : 100 nm), PL-20 (volume average particle size: 180 nm), component (2) is colloidal silica manufactured by Fuso Chemical Co., Ltd., trade name: PL-07 (volume average particle size: 7 nm), PL-1 ( Volume average particle size: 15 nm, PL-2 (volume average particle size: 25 nm), PL-3 (volume average particle size: 35 nm), and PL-5 (volume average particle size: 55 nm) were used.

<Polishing of polishing liquid>
(Example 1)
-Heterocyclic compound: 0.01% by mass of benzotriazole
Component (1): Aminomethanesulfonic acid 0.03175 mol / L
-Component (2): A-16 ... Structural formula below 0.13 mol / L
Component (3): hydrogen peroxide 0.13 mol / L
Component (4): Abrasive particles (PL-3 above) 1.5% by mass
・ PH (adjusted with ammonia water and sulfuric acid) 6.5
・ Pure water is added and the total volume is 1000mL

  An aqueous solution was prepared so that each component had the above-mentioned concentration, stirred with a high-speed homogenizer, and uniformly dispersed to obtain the polishing liquid of Example 1. The polishing test was conducted using the polishing liquid and evaluated.

<Polishing conditions>
As a polishing apparatus, an apparatus “LGP-612” manufactured by Lapmaster Co. was used, and polishing was performed under the following conditions. Specifically, while supplying the above-mentioned slurry of polishing liquid onto the polishing pad of the polishing surface plate of the polishing apparatus, the polishing surface plate and the substrate are relatively moved while the polishing substrate is pressed against the polishing pad. The metal film was polished.
Table rotation speed: 64 rpm
-Head rotation speed: 65rpm
・ Polishing pressure: 13 kPa
Polishing pad: Rohm and Haas product number IC-1400 (K-grv) + (A21)
・ Slurry supply rate: 200 ml / min

  As a substrate, a silicon oxide film (insulating film) is patterned by a photolithography process and a reactive ion etching process to form wiring grooves and connection holes (recesses) having a width of 0.09 to 100 μm and a depth of 600 nm, Further, a Ta film (barrier metal film) having a thickness of 20 nm is formed by sputtering, and then a copper film having a thickness of 50 nm is formed by sputtering, and then a copper film (conductor film) having a total thickness of 1000 nm is formed by plating. The formed 8-inch wafer was used.

(Examples 2-6, Comparative Example 1)
In Example 1, a polishing test was conducted and evaluated in the same manner as in Example 1 except that the composition of the polishing liquid was adjusted to the composition shown in Table 2.

[Evaluation item]
(Polishing speed)
-Copper and Ta films-
The film thickness difference before and after CMP of the copper film and the Ta film as the conductor film and the barrier metal film was calculated from the electric resistance value. The film thickness difference measurement was performed using VR-200 manufactured by Kokusai Denki Alpha Co., Ltd. Specifically, it was measured by polishing rate (nm / min) = [(thickness of copper and Ta film before polishing) − (thickness of copper and Ta film after polishing)] / polishing time.

-Insulating film-
The difference in film thickness before and after CMP of the silicon oxide film, which is an insulating film, was calculated from the electric resistance value. The film thickness difference was measured using F20 manufactured by Filmetrics Co., Ltd. Specifically, it was measured by polishing rate (nm / min) = [(thickness of insulating film before polishing) − (thickness of insulating film after polishing)] / polishing time.

(Selection ratio)
The selectivity calculated from the polishing rate of various films was determined. Here, the selection ratio indicates the ratio of the polishing rate of each material. A smaller ratio indicates that different films are polished uniformly.

(Scratch of copper film and Ta film)
The appearance of each substrate after polishing was visually observed. The evaluation criteria were as follows: ◯: no scratch, Δ: several scratches observed, x: a clearly problematic number of scratches observed.

(Dishing evaluation)
In addition to the time until the copper in the non-wiring portion is completely polished, the pattern wafer is polished for a time corresponding to 30% of the time, and the line-and-space portion (line 100 μm, space 100 μm) is dished. It measured with the stylus type level difference instrument name Deketak321si (made by KLA-TENCOR).

As shown in Table 2, when the polishing liquid of the example was used, it was possible to selectively change the Ta polishing rate while securing a constant polishing rate for Cu as compared with the comparative example. . It was also found that a polished surface with good flatness and no generation of scratches can be obtained.
Specifically, for Examples 1 to 5, it was revealed that the Ta polishing rate was increased by increasing the amount of aminomethanesulfonic acid added, and that Ta was polished efficiently.
Further, by adding a polishing rate adjusting agent, the selection ratio of Cu / Ta and Cu / SiO ₂ was improved, and the dishing also showed a practically no problem value.
Further, in Example 6, by adding ethyl sulfonic acid instead of aminomethane sulfonic acid, the selectivity ratio between Cu and Ta, the selectivity ratio between Cu and SiO ₂ , and dishing were the same as when amino methane sulfonic acid was added. It was found that it was possible to polish continuously with the same polishing liquid.

<Example 7>
A silicon oxide film is patterned on the surface of the silicon wafer 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. After forming a 20 nm Ta film and subsequently forming a 50 nm thick copper film by a sputtering method, a pattern wafer on which a copper film having a total thickness of 1000 nm was formed by a plating method was cut into 60 × 60 mm, The pattern wafer surface was polished with the polishing liquid of Example 3 for 120 seconds. As a result, the Cu film on the upper surface of the Ta film was removed, and the exposed Ta film was then polished with the same polishing liquid.

  When the surface of the silicon wafer after polishing was observed with an optical microscope, it was confirmed that the silicon oxide film other than the wiring groove and the Cu film in the wiring groove were exposed and the Ta film was completely removed. From this result, it was revealed that the conductor film and the barrier metal film can be continuously polished by using the polishing liquid.

Claims (6)

A barrier metal film formed over the surface of a substrate having a recess or an interlayer insulating film, and a conductor film made of copper or a copper alloy formed so as to fill the recess in the surface of the barrier metal film A polishing method for a semiconductor device that is polished with one polishing liquid, wherein the polishing liquid contains a barrier metal film polishing rate adjusting agent represented by the following general formula (I), an amino acid, an oxidizing agent, and abrasive particles. A method for polishing a semiconductor device.

[In General Formula (I), R ¹ represents H, CH ₃ , or NH ₂ . ]   The polishing method according to claim 1, wherein a molar ratio of the polishing rate adjusting agent and the amino acid is (polishing rate adjusting agent) :( amino acid) = 3: 1 to 8: 1. The polishing method according to claim 1, wherein the amino acid is a compound represented by the following general formula (II).

[In General Formula (II), R ² represents a single bond, an alkylene group, or a phenylene group, and R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, An alkenyl group, an alkynyl group, or an aryl group is represented, and R ⁵ and R ⁶ each independently represent a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or an acyl group. However, when R ² is a single bond, at least one of R ⁵ and R ⁶ is not a hydrogen atom. ]   The polishing method according to claim 1, wherein the oxidizing agent is a hydrogen peroxide solution.   The polishing method according to any one of claims 1 to 4, wherein the polishing liquid has a pH of 5 to 8. The polishing method according to claim 1, wherein the abrasive particles are silica particles.