JP2007194593A - Polishing liquid for metal and polishing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing method and a polishing liquid for metals to be used in the method, which are for polishing a substrate having an insulating film, a barrier metal film, and an electrical conductor film; and capable of polishing a residual film of the conductor film, and the barrier metal film continuously using the same polishing liquid for metals, resulting in satisfactory flatness in wiring parts and protrusions of the insulating film, and reducing scratches. <P>SOLUTION: The polishing liquid for metals is for chemical-mechanical polishing of a conductor film composed of copper or a copper alloy and a barrier metal film in semiconductor device manufacturing, and contains non-spherical grains having a ratio of the major axis to the minor axis (major axis/minor axis) of 1.2-5.0 and an oxidizer. The polishing is performed under pH5 or above. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a metal polishing liquid and a polishing method using the same, and more particularly to a metal polishing liquid used in a wiring process in manufacturing a semiconductor device and a polishing method using the same. In particular, in a chemical mechanical technique applied to copper flattening, it is used for a polishing method capable of polishing at a high speed and continuously polishing a conductor film and a barrier metal film with the same metal polishing liquid. The present invention relates to a metal polishing slurry.

  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 base are rotated, and the surface of the base 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. At present, 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 wafer central portion 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 includes one or more layers including one selected from alloys such as TaN, TaSiN, Ta, TiN, Ti, Ru, Nb, Ru, W, WN, Co, Zr, ZrN, and CuTa. It is comprised by the metal film (barrier metal film) which consists of. 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, in order to increase the production efficiency of semiconductor device production lines, a metal polishing liquid is used whose conductor film polishing rate is higher than the barrier metal film polishing rate, and the conductor film is formed using the barrier metal film as a stop layer. A two-step process of polishing and subsequently polishing the conductor film and the barrier metal film using a different metal polishing liquid 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.
JP 2001-127019 A JP 2001-279231 A JP 49-122432 A

  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 ratio (hereinafter referred to as “selection ratio”) in the conductor film, the barrier metal film, and the insulating film as much as possible.
Further, the obstacle to the realization of the one-step metal polishing liquid is that when the conductor film and the barrier film are polished continuously, there is no so-called stop 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.

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, according to the present invention, a substrate having an insulating film, a conductor film, and a barrier metal film can be continuously polished with the same metal polishing liquid, and the flatness of the polished surface after polishing is good. And it aims at providing the grinding | polishing method which can reduce generation | occurrence | production of a scratch, and the metal polishing liquid used therefor.

  As a result of intensive studies on problems in the metal polishing liquid used in the one-step process, the present inventor uses a metal polishing liquid containing specific polishing particles and an oxidizing agent and having a pH adjusted to 5 or more. As a result, the conductor film and the barrier metal film can be continuously polished with the same metal polishing liquid, and the insulating film can function as a stop layer (stopper layer). It came.

That is, the means for solving the problems are as follows.
<1> A metal-polishing liquid used for chemical mechanical polishing of a conductor film made of copper or a copper alloy and a barrier metal film in semiconductor device production, comprising the following components (1) and (2), and A polishing liquid for metals characterized by having a pH of 5 or more.
(1) Non-spherical particles having a major axis / minor axis ratio (major axis / minor axis) of 1.2 to 5.0 (2) oxidizing agent

<2> The metal polishing slurry according to <1>, wherein the non-spherical particles are bowl-shaped particles.

<3> The content of the non-spherical particles is in a range of 0.01 to 30% by mass with respect to the total mass of the metal polishing slurry, according to <1> or <2>, This is a polishing liquid for metals.

<4> The oxidizing agent is at least one selected from hydrogen peroxide, nitric acid, potassium iodate, periodic acid, potassium periodate, hypochlorous acid, and ozone water. The metal polishing liquid according to any one of claims 1 to 3.

<5> A substrate having a barrier metal film formed on the entire surface of an interlayer insulating film having a recess, 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. Wherein the conductor film and the barrier metal film are the polishing slurry for metal according to any one of <1> to <4>. A polishing method characterized by continuously polishing using

<6> While supplying the metal polishing liquid to the polishing pad affixed on the polishing surface plate, the polishing pad and the substrate are relatively moved while the polishing surface of the substrate is pressed against the polishing pad. The polishing method according to <5>, wherein the surface to be polished is polished.

<7> The polishing method according to <5> or <6>, wherein the pressure when the surface to be polished of the substrate is pressed against a polishing pad is 20 kPa or less.

<8> The polishing method according to any one of <5> to <7>, wherein the interlayer insulating film is a silicon film or an organic film.

<9> Any one of <5> to <8>, wherein the barrier metal film includes at least one selected from tantalum or a tantalum compound, titanium or a titanium compound, tungsten or a tungsten compound, and ruthenium. The polishing method according to the item.

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

The present invention will be described in detail below.
[Metal polishing liquid]
The metal-polishing liquid of the present invention is a metal-polishing liquid used for chemical mechanical polishing of a conductor film made of copper or a copper alloy and a barrier metal film in the manufacture of semiconductor devices, and comprises the following components (1) and (2) and pH is 5 or more.
(1) Non-spherical particles having a major axis / minor axis ratio (major axis / minor axis) of 1.2 to 5.0 (2) oxidizing agent

The metal polishing liquid of the present invention will be described below, but is not limited thereto.
The metal polishing slurry of the present invention contains the components (1) and (2) as essential components, and usually contains water. The metal polishing slurry of 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. The respective components (essential components and optional components) contained in the metal polishing liquid may be used alone or in combination of two or more.

In the present invention, the “metal polishing liquid” includes not only a polishing liquid used for polishing (that is, a polishing liquid diluted as necessary) but also a concentrated liquid of the metal polishing liquid. is there.
Also, the metal polishing liquid concentrate 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. Thus, it is 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 physical concentration operations such as evaporation are performed. It is used in a different way from the meaning of the general terms involved.

Hereinafter, each component will be described.
<Component (1): Non-spherical particles having a major axis / minor axis ratio (major axis / minor axis) of 1.2 to 5.0>
The metal polishing slurry of the present invention may be referred to as non-spherical particles (hereinafter simply referred to as “specific particles”) having a major axis / minor axis ratio (major axis / minor axis) of 1.2 to 5.0. ) As abrasive particles (abrasive grains).

The ratio of the major axis to the minor axis (major axis / minor axis) of the specific particles is in the range of 1.2 to 5.0. When the ratio between the major axis and minor axis of the specific particle is 5.0 or more, the polishing rate for the conductor film and the barrier metal film is not a practical value. In addition, since the polishing characteristics are almost the same as that of true spherical colloidal silica when the ratio is 1.2 or less, the insulating film can be used as a stop layer (stopper layer) in the metal polishing liquid used in the one-step process. Is not expressed.
The ratio of the major axis to the minor axis of the specific particle is preferably in the range of 1.2 to 5.0, and more preferably in the range of 3.0 to 4.5.

  In the present invention, the “major diameter” refers to the largest particle diameter portion of the specific particles (primary particles). In addition, the “minor axis” refers to the smallest particle diameter portion among the diameters intersecting with the major axis in the vertical direction. As specific particles in the present invention, the ratio of the major axis to the minor axis is in the range of 1.2 to 5.0, the major axis is in the range of 10 to 100 nm, and the minor axis is in the range of 5 to 20 nm. Those are preferred.

The major axis and minor axis of the specific particles in the present invention were determined by the following method.
That is, using “scanning electron microscope S4800 manufactured by Hitachi High-Technologies Corporation”, after grasping the shape of the whole particle, the particle is observed from the direction in which the major axis can be confirmed. Measure "major axis" and "minor axis". The values obtained by the arithmetic mean of the measured “major axis” and “minor axis” are defined as “major axis” and “minor axis” of the specific particles in the present invention.

The specific particles are preferably bowl-shaped particles from the viewpoint of providing a selective ratio of polishing rates between the conductor film and the insulating film.
Here, the “saddle shape” refers to a shape in which the vicinity or the end of the particle is recessed, or a so-called bowl shape.

  The specific particles in the present invention are preferably silica particles (precipitated silica, fumed silica, colloidal silica, synthetic silica), and are preferably colloidal silica or fumed silica because the polishing rate for copper-containing metals is high. Colloidal silica is more preferable. The specific particles are particularly preferably colloidal silica particles.

  Specific particles are colloidal silica particles manufactured by Fuso Chemical Industry Co., Ltd., trade names: PL-2 (major axis: 25 nm, minor axis: 10 nm, major axis / minor axis: 2.5), PL-5 (major axis) : 55 nm, minor axis: 14 nm, major axis / minor axis: 3.8), PL-7 (major axis: 70 nm, minor axis: 17 nm, major axis / minor axis: 4.2), PL-3L (major axis: 35 nm, short) Diameter: 33 nm, major axis / minor axis: 0.9), PL-3H (major axis: 35 nm, minor axis: 6 nm, major axis / minor axis: 6.2), PL-07 (major axis: 7 nm, minor axis: 1 nm, The major axis / minor axis: 8.3) are commercially available.

  The content of the specific particles in the metal polishing liquid of the present invention is preferably in the range of 0.01 to 30% by mass with respect to the total mass of the metal polishing liquid used for polishing. More preferably, it is in the range of ˜7% by mass. In order to obtain a sufficient effect for improving the polishing rate and reducing the variation in the polishing rate within the wafer surface, it is preferably 0.01% by mass or more, and since the polishing rate by CMP is saturated, it is 30% by mass or less. Preferably there is.

<Component (2): Oxidizing agent>
The metal polishing slurry of 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 iron (III) in addition to inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III) and iron bromide (III). Organic complex salts are preferably used.

  When an organic complex salt of iron (III) is used, examples of complex-forming compounds constituting the iron (III) complex salt include acetic acid, citric acid, oxalic acid, salicylic acid, diethyldithiocarbamic acid, succinic acid, tartaric acid, glycolic acid, glycine , Alanine, aspartic acid, thioglycolic acid, ethylenediamine, trimethylenediamine, diethylene glycol, triethylene glycol, 1,2-ethanedithiol, malonic acid, glutaric acid, 3-hydroxybutyric acid, propionic acid, phthalic acid, isophthalic acid, 3 Aminopolycarboxylic acid and its salt are mentioned other than -hydroxy salicylic acid, 3,5-dihydroxy salicylic acid, gallic acid, benzoic acid, maleic acid, etc. and these salts.

  Examples of the aminopolycarboxylic acid and salts thereof include ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid, 1,2-diaminopropane-N, N, N ′, N′-tetraacetic acid, ethylenediamine-N, N′-disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylate) Ethyl) -L-aspartic acid, N- (carboxymethyl) -L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, cyclohexanediaminetetraacetic acid, iminodiacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine 1-N , N′-Niacetic acid, ethylenediamine orthohydroxyphenylacetic acid, N, N-bis (2-hydroxybenzyl) ethylene Diamine -N, include and salts thereof such as N- diacetic acid. The kind of the counter salt is preferably an alkali metal salt or an ammonium salt, and particularly preferably an ammonium salt.

Among the oxidizing agents, hydrogen peroxide, iodate, hypochlorite, chlorate, persulfate, and organic complex salts of iron (III) are preferable, and preferable complex when using an organic complex salt of iron (III). The forming compounds are citric acid, tartaric acid, aminopolycarboxylic acid (specifically, ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ', N'-tetraacetic acid, ethylenediamine-N, N'-disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylateethyl) -L-aspartic acid, N- (carboxyl Methyl) -L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).
Among these, hydrogen peroxide, persulfate, and iron (III) ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′, N ′ -Most preferred is a complex of tetraacetic acid and ethylenediamine disuccinic acid (SS form).

  The addition amount of the oxidizing agent is preferably in the range of 0.003 mol to 8 mol, more preferably in the range of 0.03 mol to 6 mol, per liter of the metal polishing liquid used for polishing. A range of 1 mol to 4 mol is particularly preferable. That is, the addition amount of the oxidizing agent is preferably 0.003 mol or more from the viewpoint of sufficient metal oxidation and ensuring a high CMP rate, and is preferably 8 mol or less from the viewpoint of preventing roughening of the polished surface.

  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 for 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.

<PH of metal polishing liquid>
The pH of the metal polishing slurry of the present invention is 5 or more, preferably in the range of pH 5-9, more preferably in the range of pH 6-8. In this range, the metal polishing liquid of the present invention exhibits particularly excellent effects. In the polishing, the polishing liquid of the present invention may be in a form that does not contain 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 metal polishing liquid in the present invention is determined by 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 It can be set in consideration.

  The pH can be adjusted, for example, by adding an inorganic acid, an alkali agent, or an organic acid. Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid, etc. Among the inorganic acids, phosphoric acid is preferable. Examples of the alkali agent and organic acid include those described in detail later.

-Polishing characteristics of metal polishing liquid-
Here, the polishing characteristics of the metal-polishing liquid of the present invention will be specifically described with reference to the drawings. The metal polishing liquid of the present invention is a metal polishing liquid containing bowl-shaped non-spherical colloidal silica particles as specific particles and hydrogen peroxide water as an oxidizing agent. In addition, the metal polishing liquid to be compared is a polishing liquid using spherical colloidal silica particles and fumed silica particles instead of the specific particles.

FIG. 1 shows the formation of a non-spherical colloidal silica particle, a spherical colloidal silica particle, and a fumed silica particle on the silicon wafer surface using a metal polishing liquid containing 5% by mass as abrasive grains. It is a graph which shows the pH dependence of the polishing rate with respect to each metal polishing liquid at the time of grind | polishing and removing the made Cu film | membrane.
FIG. 2 shows the polishing rate pH for each metal polishing liquid when the Ta film formed on the surface of the silicon wafer is removed by polishing using the metal polishing liquid containing the three types of abrasive grains. It is a graph which shows dependence.
Further, FIG. 3 shows the pH of the polishing rate with respect to each metal polishing liquid when the TEOS film formed on the surface of the silicon wafer is polished and removed using the metal polishing liquid similarly containing the three types of abrasive grains. It is a graph which shows dependence.

  As apparent from FIG. 1, when a polishing liquid containing non-spherical colloidal silica particles is used, the polishing rate is higher in the alkaline region than in the acidic region. In contrast, when a polishing liquid containing true spherical colloidal silica particles and fumed silica particles was used, there was a tendency to show a higher polishing rate in the acidic region than in the alkaline region.

  As is apparent from FIG. 2, when a polishing liquid containing non-spherical colloidal silica particles is used, the polishing rate of Ta once decreases near pH = 4, but is generally higher in the alkaline region than in the acidic region. Indicates speed. The polishing rate of Ta in the alkaline region showed the highest value in non-spherical colloidal silica particles than in true spherical colloidal silica particles and fumed silica particles.

  As apparent from FIG. 3, when the TEOS film is polished using the spherical colloidal silica particles and the non-spherical colloidal silica particles, the polishing rate is higher in the acidic region than in the alkaline region. In other words, it has been clarified that the metal polishing liquid containing non-spherical colloidal silica hardly undergoes polishing on the alkaline side. On the other hand, when a polishing liquid containing fumed silica particles is used, a high polishing rate is exhibited in the acidic region, and the polishing rate decreases in the neutral region, but the polishing rate tends to increase again in the alkaline region.

  Accordingly, as can be seen from the results shown in FIGS. 1 to 3, by setting the pH of the metal polishing liquid containing the specific particles and the oxidizing agent to 5 or more, the substrates having the barrier metal film and the conductor film can be made identical. Since it can be continuously polished with a metal polishing liquid and the insulating film functions as a stopper layer, the flatness of the polished surface after polishing (wiring part and insulating film convex part) in CMP in one step process Flatness) and the occurrence of scratches can be reduced.

<Other ingredients>
-Heterocyclic compounds-
The metal polishing liquid of the present invention preferably contains at least one heterocyclic compound as a compound that forms a passive film on the metal surface to be polished.

  Here, the “heterocyclic compound” is a compound having a heterocyclic ring containing one or more heteroatoms. A hetero atom means an atom other than a carbon atom or a hydrogen atom. A heterocycle means a cyclic compound having at least one heteroatom. A heteroatom means only those atoms that form part of a heterocyclic ring system, either external to the ring system, separated from the ring system by at least one non-conjugated single bond, Atoms that are part of a further substituent of are not meant.

  A hetero atom is preferably a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom, and more preferably a nitrogen atom, a sulfur atom, an oxygen atom, and a selenium atom. And particularly preferably a nitrogen atom, a sulfur atom and an oxygen atom, and most preferably a nitrogen atom and a sulfur atom.

First, the heterocyclic ring that is the mother nucleus is described.
The number of members of the heterocyclic ring of the heterocyclic compound that can be used in the present invention is not particularly limited, and may be a monocyclic compound or a polycyclic compound having a condensed ring. The number of members in the case of a single ring is preferably 3 to 8, more preferably 5 to 7, and particularly preferably 5 and 6. The number of rings in the case of having a condensed ring is preferably 2 to 4, more preferably 2 or 3.

Specific examples of these heterocycles include the following. However, it is not limited to these.
For example, 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 , Pyridine 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, Lysine ring, 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 Benzthiadiazole ring, benzfuroxan ring, naphthimidazole ring, benztriazole ring, tetraazaindene ring and the like, more preferably triazole ring and tetrazole ring.

Next, substituents that the heterocyclic ring may have will be described.
In the present invention, when a specific moiety is referred to as a “group”, the moiety may be unsubstituted or substituted with one or more (up to the maximum possible) substituents. Means good. For example, “alkyl group” means a substituted or unsubstituted alkyl group.

Examples of the substituent that the heterocyclic compound may have include the following. However, it is not limited to these.
For example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched or cyclic alkyl group, and even a polycyclic alkyl group such as a bicycloalkyl group is active. A methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (regardless of the position of substitution), an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group ( Examples of the carbamoyl group having a substituent include an N-hydroxycarbamoyl group, an N-acylcarbamoyl group, an N-sulfonylcarbamoyl group, an N-carbamoylcarbamoyl group, a thiocarbamoyl group, and an N-sulfamoylcarbamoyl group), a carbazoyl group. Carboxy group or a salt thereof, oxalyl group, oxa Yl group, cyano group, carbonimidoyl group, formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy group) Or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamido group, ureido group, thioureido group, N-hydroxyureido group, Imido group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfo Luureido group, N-acylureido group, N-acylsulfamoylamino group, hydroxyamino group, nitro group, heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group ), Isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group , A sulfo group or a salt thereof, a sulfamoyl group (the sulfamoyl group having a substituent is, for example, an N-acylsulfamoyl group or an N-sulfonylsulfamoyl group) or a salt thereof, a phosphino group, a phosphinyl group, a phosphinyloxy Group, phosphinylamino group, silyl group, etc. The

  Here, “active methine group” means a methine group substituted with two electron-attracting groups. “Electron withdrawing group” means, for example, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, trifluoromethyl group, cyano group, nitro group, carvone An imidoyl group is meant. Two electron-withdrawing groups may be bonded to each other to form a cyclic structure. The “salt” means a salt with a cation such as alkali metal, alkaline earth metal or heavy metal, or an organic cation such as ammonium ion or phosphonium ion.

  Among these, preferred substituents in the heterocyclic compound include, for example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched or cyclic alkyl group, and a bicycloalkyl group). Or an active methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (regardless of the position of substitution), an acyl group, an alkoxycarbonyl group, an aryl Oxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl Group, oxalyl group, oxamoyl group, shear Group, carbonimidoyl group, formyl group, hydroxy group, alkoxy group (including groups containing repeating ethyleneoxy group or propyleneoxy group units), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) Carbonyloxy group, carbamoyloxy group, sulfonyloxy group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (alkoxy or aryl) Oxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acy Ureido group, N-acylsulfamoylamino group, hydroxyamino group, nitro group, quaternized heterocyclic group containing nitrogen atom (for example, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino Group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof Sulfamoyl group, N-acylsulfamoyl group, N-sulfonylsulfamoyl group or a salt thereof, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl group and the like. Here, the active methine group means a methine group substituted with two electron-withdrawing groups, and the electron-withdrawing group here means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl group. Examples include a sulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, and a carbonimidoyl group.

  More preferably, for example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched or cyclic alkyl group, and a polycyclic alkyl group such as a bicycloalkyl group) And may contain an active methine group), an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group (regarding the position of substitution).

  In addition, two of the above-described substituents can be combined to form a ring (aromatic or non-aromatic hydrocarbon ring or heterocyclic ring. These can be further combined to form a polycyclic fused ring. , Benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine Ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine Ring, acridine ring, phenant Phosphorus ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, phenazine ring, also form mentioned are) is.

Specific examples of the heterocyclic compound that can be particularly preferably used in the present invention include, but are not limited to, the following compounds.
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, benzotriazole, and the like.

  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 in 1 L of a metal polishing liquid used for polishing (that is, a metal polishing liquid after dilution when diluted with water or an aqueous solution). The range of -1.0 mol is preferable, More preferably, it is the range of 0.0005-0.5 mol, More preferably, it is the range of 0.0005-0.05 mol.

-Surfactant and / or hydrophilic polymer-
The metal polishing slurry of the present invention preferably contains a surfactant and / or a hydrophilic polymer. Both the surfactant and the hydrophilic polymer have the action of reducing the contact angle to the surface to be polished and the action of promoting uniform polishing.
The surfactant and / or hydrophilic polymer that can be used in the present invention is preferably an acid type, and examples of the salt include ammonium salt, potassium salt, sodium salt, and the like. Particularly preferred are ammonium salt and potassium salt. Those selected from the group are preferred.

  Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. Examples of the carboxylate salt include soap, N-acyl amino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxyl. Acid salt, acylated peptide; as sulfonate, alkyl sulfonate, alkyl benzene and alkyl naphthalene sulfonate, naphthalene sulfonate, sulfosuccinate, α-olefin sulfonate, N-acyl sulfonate; sulfate ester Salts include sulfated oil, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkyl amide sulfates; phosphate ester salts such as alkyl phosphates, polyoxyethylene or polyoxypropyls. Can pyrene alkyl allyl ether phosphates.

  As cationic surfactant, aliphatic amine salt, aliphatic quaternary ammonium salt, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt; as amphoteric surfactant, carboxybetaine type, sulfobetaine type, Mention may be made of aminocarboxylates, imidazolinium betaines, lecithins, alkylamine oxides.

Nonionic surfactants include ether type, ether ester type, ester type and nitrogen-containing type. Ether type includes polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene poly Examples include oxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, ether ester type, glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether, ester type, Polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol ester Le, sucrose esters, nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like.
In addition, a fluorine-type surfactant etc. are mentioned.

  Furthermore, other surfactants, hydrophilic compounds, hydrophilic polymers and the like include esters such as glycerin ester, sorbitan ester, methoxyacetic acid, ethoxyacetic acid, 3-ethoxypropionic acid and alanine ethyl ester; polyethylene glycol, polypropylene glycol, Polytetramethylene glycol, polyethylene glycol alkyl ether, polyethylene glycol alkenyl ether, alkyl polyethylene glycol, alkyl polyethylene glycol alkyl ether, alkyl polyethylene glycol alkenyl ether, alkenyl polyethylene glycol, alkenyl polyethylene glycol alkyl ether, alkenyl polyethylene glycol alkenyl ether, polypropylene glycol alkyl Ete , Polypropylene glycol alkenyl ethers, alkyl polypropylene glycols, alkyl polypropylene glycol alkyl ethers, alkyl polypropylene glycol alkenyl ethers, alkenyl polypropylene glycols, alkenyl polypropylene glycol alkyl ethers and alkenyl polypropylene glycol alkenyl ethers; alginic acid, pectinic acid, carboxymethylcellulose, curd Polysaccharides such as orchid and pullulan; amino acid salts such as glycine ammonium salt and glycine sodium salt; polyaspartic acid, polyglutamic acid, polylysine, polymalic acid,

  Polymethacrylic acid, poly (ammonium methacrylate), poly (methacrylic acid sodium salt), polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic Ammonium acid salt, polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid and other salts thereof; vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone and polyacrolein; methyl Tauric acid ammonium salt, methyl tauric acid sodium salt, methyl sodium sulfate salt, ethylammonium sulfate salt, butylammonium sulfate salt, vinylsulfonic acid sodium salt, 1- Rylsulfonic acid sodium salt, 2-allylsulfonic acid sodium salt, methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, 3-ethoxypropylsulfonic acid sodium salt, methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, Examples include sulfonic acids such as 3-ethoxypropylsulfonic acid sodium salt and sulfosuccinic acid sodium salt and amides such as propionamide, acrylamide, methylurea, nicotinamide, succinic acid amide, and sulfanilamide.

  However, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, contamination with an alkali metal, an alkaline earth metal, a halide, or the like is not desirable, so an acid or an ammonium salt thereof is desirable. This is not the case when the substrate is a glass substrate or the like. Among the above exemplified compounds, cyclohexanol, polyacrylic acid ammonium salt, polyvinyl alcohol, succinic acid amide, polyvinyl pyrrolidone, polyethylene glycol, and polyoxyethylene polyoxypropylene block polymer are more preferable.

  The addition amount of the surfactant and / or the hydrophilic polymer is preferably in the range of 0.001 to 10 g in 1 L of the metal polishing slurry when used for polishing as a total amount, and 0.01 to 5 g. The range is more preferable, and the range of 0.1 to 3 g is particularly preferable. That is, the addition amount of the surfactant and / or the hydrophilic polymer is preferably 0.001 g or more for obtaining a sufficient effect, and is preferably 10 g or less from the viewpoint of preventing the CMP rate from being lowered.

Moreover, as a weight average molecular weight of these surfactant and / or hydrophilic polymer, the range of 500-100000 is preferable, and the range of 2000-50000 is especially preferable.
Only one type of surfactant may be used, two or more types may be used, and different types of surfactants may be used in combination.

-Organic acids, chelating agents, alkalis, buffers-
In the present invention, it is preferable to further add an organic acid, a chelating agent, an alkali, and a buffer. Hereinafter, organic acids, chelating agents, alkalis and buffering agents that can be used in the present invention will be described.

  The metal polishing slurry of the present invention preferably contains an organic acid. The organic acid here is a compound having a structure different from that of an oxidizing agent for oxidizing a metal, and does not include an acid that functions as the above-described oxidizing agent. The organic acid here has the action of promoting oxidation, adjusting pH, and buffering agent.

  An organic acid is an organic compound that generates an acid, and preferably has at least one carboxyl group. The organic acid is preferably water-soluble, and more preferably amino acids.

  As the organic acid, those selected from the following group are suitable. That is, amino acids, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalate Acid, malic acid, tartaric acid, citric acid, lactic acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, diethylhydroxyglycine, and salts thereof such as ammonium salt and alkali metal salt, sulfuric acid, nitric acid, ammonia, ammonium salts, or those And the like.

The amino acids are preferably water-soluble. What was chosen from the following groups is more preferable.
That is, 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-diodo-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- Cystic acid, L-aspartic acid, L-glutamic acid, S- (carboxymethyl) -L-cysteine, 4-aminobutyric acid Acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-kynurenine, L-histidine, 1-methyl-L-histidine, Examples include amino acids such as 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II, and antipine.

  Among these organic acids, formic acid, malonic acid, malic acid, tartaric acid, citric acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, and diethylhydroxyglycine are preferred.

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

The metal 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 in 1 L of a metal polishing liquid used for polishing. 0.07 mol is added.

  Moreover, the metal polishing liquid of the present invention can contain an alkali agent for pH adjustment and further a buffering agent from the viewpoint of suppressing pH fluctuations, 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 the alkali agent and buffer include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, diphosphate phosphate. Sodium, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, sodium o-hydroxybenzoate (sodium salicylate), potassium o-hydroxybenzoate, 5-sulfo Examples include sodium 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 metal polishing liquid is preferably in the range of 0.8 to 1.5 from the viewpoint of fluidity of the liquid and stability of the polishing performance, and preferably 0.95 to 1.35. The range is particularly preferable.

[Polishing method]
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 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. The conductive film and the barrier metal film are continuously polished using the metal polishing liquid of the present invention. It is characterized by.

  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 metal polishing liquid is chemically and mechanically polished, and then applied to the same metal. A chemical mechanical polishing method using a metal polishing liquid capable of continuously polishing a residual film of a conductor film and a barrier metal film with a polishing liquid, and as the metal polishing liquid, A polishing liquid is used.

  The metal polishing liquid used in the polishing method of the present invention is a concentrated liquid, and when used, it is diluted by adding water to make a working liquid, or each component is mixed in the form of an aqueous solution described later. However, if necessary, it may be diluted by adding water to obtain a working solution, or it may be prepared as a working solution. Although it does not restrict | limit especially as a metal polishing liquid in this invention, Any said aspect is applicable in this invention.

  In the polishing method of the present invention, a metal-polishing liquid is supplied to a polishing pad on a polishing surface plate, and this is brought into contact with the surface to be polished to cause the surface to be polished and the polishing pad to move relative to each other (relatively move). A polishing method for polishing.

  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.

Furthermore, the polishing pad may contain abrasive grains (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 by 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 about 2 kPa.

  During polishing, a polishing liquid for metal 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 metal polishing liquid is the same as the aqueous solution described below. The aqueous solution is a water containing at least one of an oxidizing agent, an acid, an additive, and a surfactant in advance, and a component obtained by totaling the components contained in the aqueous solution and the components of the metal polishing liquid to be diluted, It becomes the component at the time of grinding | polishing using the metal polishing liquid. When the metal polishing liquid is diluted with an aqueous solution, components that are difficult to dissolve can be blended in the form of an aqueous solution, and a more concentrated metal polishing liquid can be prepared.

  As a method of diluting by adding water or an aqueous solution to the concentrated metal polishing liquid, the pipe for supplying the concentrated metal polishing liquid and the pipe for supplying the water or the aqueous solution are joined together and mixed, mixed and diluted. There is a method of supplying the polished metal polishing liquid to the 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 a 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 metal polishing liquid is preferably in the range of 10 to 1000 ml / min. In order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern, the supply rate is preferably in the range of 170 to 800 ml / min. More preferred.

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

  In the present invention, the component to be contained in the metal polishing liquid is divided into at least two components, and when they are used, water or an aqueous solution is added and diluted to be supplied to the polishing pad on the polishing platen, 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 can also be used.

For example, an oxidant is one component (A), an acid, an additive, a surfactant, and water are one component (B). The component (B) is diluted before 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 the diluted metal 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 in the metal polishing slurry.

  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 component of the metal 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 metal polishing liquid may be a concentrated liquid, and the diluted water may be separately supplied to the polishing surface.

  As a method for supplying the metal polishing liquid, as described above, when the metal polishing liquid component is divided into two or more parts and supplied to the polishing surface, the metal polishing liquid is used as a concentrate, and dilution water is used. Another distinction is made when supplying to the polishing surface. However, in any of the methods for supplying a metal polishing liquid, in the polishing method of the present invention, after chemical mechanical polishing of a conductor film formed on a convex portion of an insulating film with one type of metal polishing liquid, Subsequently, the remaining film of the conductor film and the barrier metal film can be continuously polished with the same metal polishing liquid.

  The object to be polished by the polishing method of the present invention is a barrier metal film formed on the entire surface of an interlayer insulating film having a recess, and copper or copper formed so that the recess is buried in the surface of the barrier metal film. A conductive film made of an alloy, which is a semiconductor substrate, preferably an LSI having wiring made of copper metal and / or copper alloy, and in particular, the wiring is made of a copper alloy. 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 metal 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 metal polishing liquid of the present invention 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.

(Interlayer insulation film)
The polishing method using the metal polishing liquid of the present invention can be used not only for flattening a conductor film (wiring) on a substrate but also for flattening a multilayer wiring board. In this case, the conductor film (wiring) formed on the interlayer insulating film can be planarized.
The interlayer insulating film in the present invention preferably has a dielectric constant of 2.6 or less, and examples thereof include a silica-based film and an organic interlayer insulating film. Particularly, carbon is doped. It is preferable to use a silica-based film.
The thickness of the interlayer insulating film can be appropriately adjusted depending on the upper and lower portions of the wiring in the multilayer wiring, or between generations (nodes).

(Barrier metal film)
The barrier metal film is a film (layer) for preventing diffusion of copper between a conductor film (wiring) made of copper or a copper alloy provided on a semiconductor substrate and an interlayer insulating film.
The material of the barrier layer 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 20 to 30 nm.

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

<Specific particles>
Specific particles are colloidal silica particles manufactured by Fuso Chemical Industry Co., Ltd., and trade names: PL-2 (major axis: 25 nm, minor axis: 10 nm, major axis / minor axis: 2.5), PL-5 ( Major axis: 55 nm, minor axis: 14 nm, major axis / minor axis: 3.8), PL-7 (major axis: 70 nm, minor axis: 17 nm, major axis / minor axis: 4.2), PL-3L (major axis: 35 nm, Minor axis: 33 nm, major axis / minor axis: 0.9), PL-3H (major axis: 35 nm, minor axis: 6 nm, major axis / minor axis: 6.2), PL-07 (major axis: 7 nm, minor axis: 1 nm) , Long diameter / short diameter: 8.3), which is commercially available. The type of specific particles used in each example will be described later.

<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 a slurry of a metal polishing liquid to be described later onto a polishing pad of a polishing surface plate of a polishing apparatus, the polishing surface plate and the substrate are relatively moved while being pressed against the polishing pad. To polish the metal film.
Table rotation speed: 64 rpm
-Head rotation speed: 65 rpm
Polishing pressure: 13 kPa
・ Polishing pad: Part number IC-1400 manufactured by Rodel Nitta Co., Ltd.
・ 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.

[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.

(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.

<Example 1>
-Metal polishing composition-
・ Benzotriazole 0.01% by mass
Abrasive grains (specific particles) (PL-2, non-spherical colloidal silica) 10% by mass
・ Hydrogen peroxide (oxidant) 1% by mass
・ Glycine (organic acid) 0.8% by mass
・ PH (adjusted with ammonia water and sulfuric acid) 6.5

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

  Using the metal polishing liquid obtained as described above, polishing was performed under the above conditions, and the above items were evaluated. The results are shown in Table 1.

<Examples 2-3 and Comparative Examples 1-3>
In Example 1, except that the abrasive grains (specific particles) used in the metal polishing liquid were changed as shown in Table 1, each metal polishing liquid was prepared in the same manner as in Example 1, and these were used. The same polishing was performed and the same evaluation was performed.

<Comparative example 4>
In Example 1, each metal polishing liquid was prepared in the same manner as in Example 1 except that the abrasive grains (specific particles) used in the metal polishing liquid and the pH of the polishing liquid were changed as shown in Table 1. Then, the same polishing was performed using these, and the same evaluation was performed.
The results are summarized in Table 1.
As a result of the polishing test, the polishing rate of various films and the selection ratio calculated from the polishing rate are also shown in Table 1. Here, the “selection ratio” indicates a ratio of polishing rates of the respective materials. A smaller ratio indicates that different films are polished uniformly.

As shown in Table 1, when the metal polishing liquid of the example is used, a polished surface with good flatness of the surface to be polished and no generation of scratches while ensuring a constant polishing rate. It turns out that you can get.
Specifically, it was found that the Cu film can be polished at a high polishing rate when the ratio of the major axis to minor axis (major axis / minor axis) of the specific particles is in the range of 1.2 to 5.0. Further, as is clear from Comparative Examples 2 and 5, when abrasive grains outside the range of component (1) were used, it was confirmed that the polishing rate of the Cu film was extremely reduced or scratched. It was.

  Further, it was found that the Ta film is efficiently polished when the ratio of the major axis to the minor axis (major axis / minor axis) of the component (1) is in the range of 1.2 to 5.0.

  In the results shown in Comparative Example 3, when particles having a major axis / minor axis ratio (major axis / minor axis) of component (1) of greater than 5.0 were used, the Cu polishing rate showed a very high value. However, when the polished silicon wafer surface with the Cu film was observed with an optical microscope, it was confirmed that many scratches were generated on the surface. Furthermore, when the surface of the polished silicon wafer with a Ta film was observed with an optical microscope, it was confirmed that many scratches were generated on the surface.

  As a result of Comparative Example 4, when pH = 2, the Cu polishing rate showed a high value, but the Ta polishing rate decreased, and the TEOS film polishing rate showed a high value.

  As a result of Comparative Example 5, when pH = 10, the Ta polishing rate and the TEOS film polishing rate showed good values, but the Cu polishing rate was extremely reduced.

<Example 4>
A silicon oxide film is patterned on the silicon wafer surface 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, and further sputtering. A pattern in which a Ta film (barrier metal film) having a thickness of 20 nm is formed by a sputtering method, a copper film having a thickness of 50 nm is subsequently formed by a sputtering method, and then a copper film (conductor film) having a total thickness of 1000 nm is formed by a plating method. Using a wafer (substrate) cut to 60 × 60 mm, the pattern wafer surface was polished with the metal polishing liquid of Example 2 for 60 seconds.

  As a result, the Cu film on the upper surface of the Ta film is removed at a polishing rate of approximately 700 nm / min, and the Ta film exposed thereafter is polished at a rate of 60 nm / min, and each is polished with the same metal polishing liquid. Became.

  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. all right.

  Furthermore, when the surface of the interlayer insulating film was observed with an optical microscope, scratches were hardly observed.

It is a graph which shows the pH dependence of the grinding | polishing speed | rate at the time of carrying out grinding | polishing removal of Cu film | membrane using the metal polishing liquid and other metal polishing liquid containing a non-spherical particle. It is a graph which shows the pH dependence of the grinding | polishing speed | rate at the time of grind | polishing and removing Ta film | membrane using the metal polishing liquid containing other non-spherical particles, and another metal polishing liquid. It is a graph which shows the pH dependence of the grinding | polishing speed | rate at the time of grind | polishing and removing a TEOS film | membrane using the metal polishing liquid and other metal polishing liquid containing a non-spherical particle.

Claims (9)

A metal-polishing liquid used for chemical mechanical polishing of a conductor film made of copper or a copper alloy and a barrier metal film in the manufacture of semiconductor devices, comprising the following components (1) and (2), and having a pH of 5 A metal polishing slurry characterized by the above.
(1) Non-spherical particles having a major axis / minor axis ratio (major axis / minor axis) of 1.2 to 5.0 (2) oxidizing agent   The metal polishing slurry according to claim 1, wherein the non-spherical particles are bowl-shaped particles.   The metal polishing liquid according to claim 1 or 2, wherein the content of the non-spherical particles is in a range of 0.01 to 30% by mass with respect to the total mass of the metal polishing liquid. .   The oxidant is at least one selected from hydrogen peroxide, nitric acid, potassium iodate, periodic acid, potassium periodate, hypochlorous acid, and ozone water. Item 4. The metal polishing slurry according to any one of Items 3 above.   A substrate having a barrier metal film formed over the entire surface of the interlayer insulating film having a recess, 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, 5. A method for polishing a surface on a conductor film side as a surface to be polished, wherein the conductor film and the barrier metal film are continuously formed using the metal polishing liquid according to claim 1. Polishing method characterized by performing polishing.   While supplying the metal polishing liquid to the polishing pad affixed on the polishing surface plate, the polishing pad and the substrate are relatively moved while the polishing surface of the substrate is pressed against the polishing pad. The polishing method according to claim 5, wherein the polishing surface is polished.   The polishing method according to claim 5 or 6, wherein a pressure when the surface to be polished of the substrate is pressed against a polishing pad is 20 kPa or less.   The polishing method according to claim 5, wherein the interlayer insulating film is a silicon-based film or an organic film.   The said barrier metal film contains at least 1 sort (s) chosen from a tantalum or a tantalum compound, titanium or a titanium compound, tungsten or a tungsten compound, and ruthenium, The any one of Claim 5-8 characterized by the above-mentioned. Polishing method.

Images