JP2008071810A - Method of polishing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing method of a semiconductor device in which the occurrence of dishing and erosion can be controlled, and excellent flatness is imparted to the semiconductor device without producing scratches. <P>SOLUTION: The polishing method for planarizing a semiconductor device having a conductor film principally comprising copper includes (a) a step of polishing a conductor layer with polishing solution containing a compound represented by general formula (1) or (2), an oxidizing agent and abrasive grains at a chemical mechanical polishing speed of 300 nm/min or above and at an etching speed of 70 nm/min or above, and (b) a step of polishing a conductor layer with polishing solution containing a compound represented by general formula (3), an oxidizing agent and abrasive grains at a chemical mechanical polishing speed of 300 nm/min or less and at an etching speed of 15 nm/min or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to manufacturing of semiconductor devices, and more particularly to a polishing method applied to copper planarization CMP technology in a wiring process of semiconductor devices.

  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 into a dish shape.

  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 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”).

In the conventional polishing method, first, a metal polishing liquid capable of polishing the conductor layer with high efficiency is used, and the conductor layer is polished at a high polishing rate until the barrier layer in a portion other than the recess is exposed, and then mainly, By using a metal-polishing liquid that can polish the barrier layer with high efficiency and polishing the barrier layer at a high polishing rate until the insulator layer in the portion other than the recess is exposed, a wiring portion is formed in the recess. It was.
This method has a problem in that dishing and erosion occur due to excessive polishing of the conductor layer in order to polish the conductor layer at a high polishing rate.

In addition, as another conventional method, after forming a conductor layer on the barrier layer, a polishing solution for metal that can polish the conductor layer with high efficiency is used, and polishing is performed before the barrier layer other than the recess is exposed. The conductive layer is polished at a high polishing rate so that the conductive layer and the barrier layer can be polished with high efficiency, and the insulator layer at portions other than the recesses is exposed. A method for forming a wiring portion in a recess has been performed by polishing the barrier layer.
In this conventional technology, when the conductor layer and the barrier layer are polished, the electrochemical reaction proceeds between the conductor layer and the barrier layer, and the conductor layer is selectively polished, so that dishing occurs. There was a problem to do.
JP 2001-127019 A JP 2001-279231 A JP 49-122432 A

  An object of the present invention made in view of the above-mentioned problems of the prior art is to polish a semiconductor device that can suppress the occurrence of dishing and erosion, and gives excellent flatness to the semiconductor device without causing scratches. It is to provide a method.

  As a result of earnestly examining the problems in the metal polishing liquid used in the conventional polishing method, the present inventor uses a metal polishing liquid in which the etching rate is defined at each polishing stage in order to achieve the above object. As a result, it was found that the occurrence of dishing and erosion can be suppressed, and the present invention was completed.

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

<1> A polishing method for flattening a semiconductor device having a conductor film containing copper as a main component, wherein the semiconductor film is polished in a polishing step including the following steps (a) and (b): .
(A) In a polishing liquid containing a compound represented by the following general formula (1) or general formula (2), an oxidizing agent and abrasive grains, a chemical mechanical polishing rate of 300 nm / min or more with respect to the conductor layer, and Polishing at an etching rate of 70 nm / min or more,
(B) In a polishing liquid containing a compound represented by the following general formula (3), an oxidizing agent and abrasive grains, a chemical mechanical polishing rate of 300 nm / min or less and an etching rate of 20 nm / min or less with respect to the conductor layer. The process of polishing with.

  In the method of the present invention, the step (a) is a step of polishing the conductor layer so that the polishing is finished before the barrier layer is exposed, and the chemical mechanical polishing rate for the conductor layer is preferably 300 nm / min or more, preferably Is represented by the following general formula (1) or general formula (2) which is an organic acid capable of achieving 300 to 800 nm / min and an etching rate for the conductor layer of 70 nm / min or more, preferably 70 to 140 nm / min. This is a step of polishing at a polishing rate and an etching rate using a polishing liquid containing a compound, an oxidizing agent, and abrasive particles. Step (b) is a step of polishing the conductor layer until the barrier layer is exposed, and the chemical mechanical polishing rate for the conductor layer is 300 nm / min or less, preferably 150 to 300 nm / min, and An organic acid represented by the following general formula (3), which is an organic acid capable of achieving an etching rate of 20 nm / min or less, preferably 10 to 15 nm / min with respect to the conductor layer, an oxidizing agent, and polishing particles The conductor layer is polished at a polishing rate and an etching rate until the barrier layer is exposed.

The polishing rate in the present invention is obtained by converting the film thickness difference before and after polishing of the conductor film and the barrier metal film from the electric resistance value and using the value measured by the following equation (1). The film thickness difference measurement was performed using VR-200 manufactured by Kokusai Denki Alpha Co., Ltd.
Formula (1): Polishing rate (nm / min) =
[(Thickness of copper and Ta film before polishing) − (Thickness of copper and Ta film after polishing)] / Polishing time.
In the etching rate in the present invention, a wafer coated with copper (hereinafter referred to as a copper solid film wafer) is immersed for 1 minute in a metal abrasive that has been previously removed of abrasive components and adjusted to a temperature of 40 ° C. The amount of copper eluted in the metal abrasive (hereinafter referred to as the etching amount) was quantified with an ICP emission analyzer ICP-1000IV (manufactured by Shimadzu Corporation). Furthermore, the film thickness of the dissolved copper was calculated from the etching amount by the following formula (2), and was used as the etching rate.
Formula (2): Etching rate (nm / min) =
[(Etching amount) / (abrasive liquid amount)] / (specific gravity of copper) / (area of sample wafer)

In the general formula (1), R ¹ represents a single bond, an alkylene group, or a phenylene group.
R ² and R ³ each independently represents a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ⁴ represents a hydrogen atom, a halogen atom, an alkyl group or an acyl group. R ⁵ represents an alkylene group. However, when R ⁵ is —CH ₂ —, R ¹ is an alkylene group or a phenyl group, and / or R ⁴ is any one of a halogen atom and an alkyl group.

In the general formula (2), R ⁶ represents a single bond, an alkylene group, or a phenylene group.
R ⁷ and R ⁸ each independently represents a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ⁹ represents an alkylene group, and R ¹⁰ represents a single bond, an alkylene group, an alkyleneoxy group or a phenylene group. However, when R ⁹ is —CH ₂ —, R ⁶ is any one of an alkylene group, a phenyl group, and / or R ¹⁰ is an alkylene group, an alkyleneoxy group, or a phenylene group.

In the general formula (3), R ^a represents a single bond, an alkylene group, or a phenylene group.
R ^b and R ^c each independently represents a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group.
R ^d and R ^e each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an acyl group.
However, when R ^a is a single bond, at least one of R ^d and R ^e is not a hydrogen atom.

<2> In the steps (a) and (b), the oxidizing agent contained in the polishing liquid is a hydrogen peroxide solution, and a polishing liquid having a concentration of 0.01 to 1.5 mol / L is used. The method for polishing a semiconductor device according to <1>, characterized in that it is characterized in that:
<3> In the steps (a) and (b), the abrasive contained in the polishing liquid is silica particles, and a polishing liquid having a concentration of 0.0001 to 5 wt% is used <1 The method for polishing a semiconductor device according to <1>.

  The present invention includes a first polishing step of polishing a conductive layer so that the substrate having the conductive film and the barrier metal film is finished before the barrier layer is exposed, and polishing the conductive layer until the barrier layer is exposed. Therefore, according to the present invention, the occurrence of dishing and erosion is suppressed, and the occurrence of scratches is prevented, and the polishing of a semiconductor device with good flatness of the polished surface after polishing is achieved. A method can be provided.

First, a metal polishing liquid (hereinafter also referred to as “the metal polishing liquid of the present invention”) 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.
In the polishing method of the present invention, as described above, the step (a) of polishing the conductor film to finish polishing before the barrier layer is exposed and the step (b) of polishing the conductor layer until the barrier layer is exposed. Therefore, a suitable polishing liquid will be described.

[Metal polishing liquid used in step (a)]
(A) The metal polishing liquid used in the step includes (i) a compound (organic acid) represented by the following general formula (1) or general formula (2), (ii) an oxidizing agent, and (iii) an abrasive. Contains grains.

The metal polishing liquid that can be used in the step (a) of the present invention (hereinafter, appropriately referred to as the metal polishing liquid for the step (a)) contains the components (i) to (iii) as essential components. Characteristic and usually composed of water. The metal polishing slurry for step (a) 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.
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.
<(I) Compound represented by the following general formula (1) or general formula (2)>
This compound is an organic acid and is useful for controlling the polishing rate.

In the general formula (1) and the general formula (2), R ¹ and R ⁶ each independently represents a single bond, an alkylene group, or a phenylene group.
R ² , R ³ , R ⁷ and R ⁸ each independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ⁴ represents a hydrogen atom, a halogen atom, an alkyl group or an acyl group. R ⁵ and R ⁹ represent an alkylene group, and R ¹⁰ represents a single bond, an alkylene group, an alkyleneoxy group, or a phenylene group. However, when R ⁵ is —CH ₂ —, R ¹ is an alkylene group or a phenyl group, and / or R ⁴ is any one of a halogen atom and an alkyl group, and R ⁹ is —CH ₂ —. R ⁶ is an alkylene group or a phenyl group, and / or R ¹⁰ is any one of an alkylene group, an alkyleneoxy group, or a phenylene group.

  The compounds represented by the general formulas (1) and (2) are an amino acid having two or more carboxyl groups (aminodicarboxylic acid (shown by the general formula (1)) that exhibit oxidation action, pH adjustment, and buffering action. ) Or aminotricarboxylic acid (shown by the general formula (2)).

The alkylene group as R ¹ and R ⁵ in the general formula (1) may be any one of linear, branched and cyclic, and is preferably an alkylene group having 1 to 8 carbon atoms. , Methylene group and ethylene group.
The alkylene group as R ¹ and R ⁵ and the phenylene group as R ⁵ may have a substituent, and examples of the substituent that can be introduced here include a hydroxyl group and a halogen atom.

The alkyl group as R ² and R ³ in the general formula (1) is preferably an alkyl group having 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group.
The cycloalkyl group as R ² and R ³ in the general formula (1) is preferably a cycloalkyl group having 5 to 15 carbon atoms, and examples thereof include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.
The alkenyl group as R ² and R ³ in the general formula (1) is preferably an alkenyl group having 2 to 9 carbon atoms, and examples thereof include a vinyl group, a propenyl group, and an allyl group.
The alkynyl group as R ² and R ³ in the general formula (1) is preferably an alkynyl group having 2 to 9 carbon atoms, and examples thereof include an ethynyl group, a propynyl group, and a butynyl group.
The aryl group as R ² and R ³ in the general formula (1) is preferably an aryl group having 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 in its structure.
Examples of the substituent that each group represented by R ² and R ³ in the general formula (1) may have include a hydroxyl group, a halogen atom, and an aromatic ring (preferably an aromatic ring having 3 to 15 carbon atoms). it can.

The alkyl group as R ⁴ in the general formula (1) is preferably an alkyl group having 1 to 8 carbon atoms, and examples thereof include a methyl group and an ethyl group.
The acyl group as R ⁴ in the general formula (1) is preferably an acyl group having 2 to 9 carbon atoms, and examples thereof include a methylcarbonyl 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 ⁴ in the general formula (1) may have include a hydroxyl group, an amino group, and a halogen atom.
In the general formula (I), R ⁴ is preferably not a hydrogen atom.

Although the specific example of a compound represented by General formula (1) below is shown below by specifying the functional group in following General formula (1), it is not limited to these.

  The structure of aminotricarboxylic acid can be represented by the following general formula (2).

In general formula (2), R ⁶ represents a single bond, an alkylene group, or a phenylene group. R ⁷ and R ⁸ each independently represents a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ⁵ represents an alkylene group. R ⁶ represents a single bond, an alkylene group, an alkyleneoxy group or a phenylene group. However, when R ⁹ is —CH ₂ —, R ⁶ is any one of an alkylene group, a phenyl group, and / or R ¹⁰ is an alkylene group, an alkyleneoxy group, or a phenylene group.

The alkylene group as R ⁶ and R ¹⁰ in the general formula (2) may be any one of linear, branched, and cyclic, and is preferably an alkylene group having 1 to 8 carbon atoms. , Methylene group and ethylene group.
Examples of the substituent that the alkylene group as R ⁶ and R ⁹ and the phenylene group as R ¹⁰ in General Formula (2) may have include a hydroxyl group and a halogen atom.

The alkyl group as R ⁷ and R ⁸ in the general formula (2) is preferably an alkyl group having 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group.
The cycloalkyl group as R ⁷ and R ⁸ in the general formula (2) is preferably a cycloalkyl group having 5 to 15 carbon atoms, and examples thereof include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.
The alkenyl group as R ⁷ and R ⁸ in the general formula (2) is preferably an alkenyl group having 2 to 9 carbon atoms, and examples thereof include a vinyl group, a propenyl group, and an allyl group.
The alkynyl group as R ⁷ and R ⁸ in the general formula (2) is preferably an alkynyl group having 2 to 9 carbon atoms, and examples thereof include an ethynyl group, a propynyl group, and a butynyl group.
The aryl group as R ⁷ and R ⁸ in the general formula (2) is preferably an aryl group having 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 represented by R ⁷ and R ⁸ in the general formula (2) may have include a hydroxyl group, a halogen atom, and an aromatic ring (preferably an aromatic ring having 3 to 15 carbon atoms). it can.

The alkylene group as R ⁶ in the general formula (2) is preferably an alkylene group having 1 to 8 carbon atoms, and examples thereof include a methylene group and an ethylene group.
The alkyleneoxy group as R ⁶ in the general formula (2) is preferably an alkyleneoxy group having 1 to 8 carbon atoms, and examples thereof include a methyleneoxy group and an ethyleneoxy group.

  Although the specific example of a compound represented by General formula (2) below is shown below by specifying the functional group in following General formula (2), it is not limited to these.

  The addition amount of aminodicarboxylic acid or aminotricarboxylic acid is preferably 0.0005 to 0.5 mol, more preferably 0.005 mol to 0.3 mol, in 1 L of a polishing liquid used for polishing. Preferably, 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.

<(Ii) Oxidizing agent>
In the present invention, (ii) an oxidizing agent (a compound capable of oxidizing a metal to be polished) is contained in any of the metal polishing liquids used in the step (a) and further in the step (b) described later.
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.
Above all, from the viewpoint of ensuring a sufficiently high CMP rate for metal oxidation and preventing roughening of the polished surface, from hydrogen peroxide, nitric acid, potassium iodate, periodic acid, potassium periodate, hypochlorous acid, and ozone water It is preferably at least one selected.

  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.

  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 aminopolycarboxylic acids and salts thereof include ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid, , 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'-diacetic acid, ethylenediamine orthohydroxyphenylacetic acid, N, N-bis (2-hydroxybenzidine ) Ethylenediamine -N, it includes 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 them, hydrogen peroxide, iodate, hypochlorite, chlorate, persulfate, and an organic complex salt of iron (III) are preferable, and a preferable complex-forming compound when an organic complex salt of iron (III) is used is 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), ethylenediaminedisuccinic acid (SS), N- (2-carboxylateethyl) -L-aspartic acid, N- (carboxymethyl)- L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).

  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 mol to 8 mol, and preferably in the range of 0.03 mol to 6 mol, per liter of the metal polishing liquid when used for polishing in any polishing liquid. Is more preferable, and the range of 0.1 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 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.

<(Iii) Abrasive particles>
In the present invention, the (a) step, the (b) step described later, and the metal polishing liquid used for the barrier layer polishing step all contain abrasive grains. As polishing particles (abrasive grains) that can be used in the present invention, any of inorganic abrasive grains such as silica, alumina, ceria, titania, zirconia, germania, silicon carbide, and organic abrasive grains such as polystyrene, polyacryl, polyvinyl chloride, etc. But you can. Among these, at least one selected from silica, alumina, ceria, titania, zirconia, and germania is preferable, the dispersion stability in the polishing liquid is good, and the number of occurrences of polishing scratches (scratches) generated by CMP is high. Less silica (precipitated silica, fumed silica, colloidal silica, synthetic silica) is preferred. The silica is preferably colloidal silica or fumed silica, and more preferably colloidal silica because of its high polishing rate for copper-containing metals.

Further, the polishing particles contained in the metal polishing liquid according to the present invention are particles having a volume average particle diameter in the range of 60 to 150 nm determined by a dynamic light scattering method.
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 aforementioned nitride can be obtained, for example, by heating the oxide together with a reducing agent such as carbon in a nitrogen atmosphere. In this case, it is very important how the temperature distribution in the reactor is made uniform so as not to cause welding between particles while causing the reduction reaction. If the particles contain welded particles, give these powders velocity energy and disperse them by colliding them with the shielding plate. In the case of strong aggregates, disperse them in a solvent to form a slurry. In general, a method is used in which physical energy is applied and dispersed using an apparatus such as a high-pressure homogenizer.

  The total amount of abrasive grains added is preferably in the range of 0.02 to 15% by mass with respect to the total mass of the metal polishing liquid when used in any polishing liquid, A range of 5% by mass is more preferable. In order to obtain a sufficient effect for improving the polishing rate and reducing variations in the polishing rate within the wafer surface, 0.02% by mass or more is preferable, and since the polishing rate by CMP is saturated, 15% by mass or less is preferable.

<PH of metal polishing liquid>
The pH of the metal 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 3 to 9. 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, etc. It can be set in consideration.
The pH can be adjusted, for example, by adding an alkali agent described later, or by adding an organic acid other than the compound represented by the general formula (3) used in the step (b).
(A) Since the end point of the process is completed before the barrier metal film is exposed, a method of controlling the polishing time in advance in consideration of the thickness of the metal film in the shape of the barrier film measured in advance and the polishing rate, or "Torque measurement method" that detects changes in the friction coefficient between the wafer to be polished and the polishing cloth as changes in the rotation axis torque of the wafer carrier and surface plate, and the sheet resistance of the metal film adhering to the wafer surface is inversely proportional to the thickness Is determined by a detection method such as an “electrical resistance measurement method” that measures the thickness of the metal film being processed.

[(B) Metal polishing liquid used in step]
The metal polishing liquid used in the step (b) includes (iv) a compound (organic acid) represented by the following general formula (3), (ii) an oxidizing agent, and (iii) abrasive grains.

The metal-polishing liquid of the present invention is characterized by containing the components (iv), (ii), and (iii) as essential components, and usually comprises water. The (ii) oxidizing agent and (iii) abrasive grains in the metal polishing liquid for step (b) in the present invention are the same as those in the metal polishing liquid for step (a) described above. The same applies to the above. Moreover, the point which may contain another component further if desired is also the same, and the compound (heterocyclic compound etc.), surfactant, and / or preferable as a passive film formation agent as another preferable component are preferable. Additives such as hydrophilic polymers, acids, alkalis, and buffering agents will be described later.
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.

<(IV) Compound represented by the following general formula (3)>
The metal polishing slurry for step (b) of the present invention contains an amino acid (organic acid) having a carboxyl group, which exhibits an action of promoting oxidation, pH adjustment, and a buffer, and this amino acid is an amino monocarboxylic acid. Is included.
The structure of a suitable amino monocarboxylic acid can be represented by the following general formula (3).

R ^a represents a single bond, an alkylene group, or a phenylene group.
R ^b and R ^c each independently represents a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group.
R ^d and R ^e each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an acyl group.
However, when R ^a is a single bond, at least one of R ^d and R ^e is not a hydrogen atom.

The alkylene group as R _a in the general formula (3) 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 ^b and R ^c preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group.
The cycloalkyl group as R ^b and R ^c 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 ^b and R ^c 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 ^b and R ^c 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 ^b and R ^c 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 ^b and R ^c may have include a hydroxyl group, a halogen atom, an aromatic ring (preferably having 3 to 15 carbon atoms), an amino group, and the like.

The alkyl group as R ^d and R ^e 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 as R ^d and R ^e may have include a hydroxyl group, an amino group, and a halogen atom.

In general formula (3), it is preferable that either one of R ^d and R ^e is not a hydrogen atom.

In the general formula (3), it is particularly preferable that R ^a is a single bond, and R ^b and R ^d are hydrogen atoms. In this case, R ^c represents a hydrogen atom, a halogen atom, 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 ^e represents a hydrogen atom, a halogen atom, an alkyl group, or an acyl group, and an alkyl group is particularly preferable. As the substituent that the alkyl group as R ^c may have, a hydroxyl group or an amino group is preferable. As the alkyl group substituent which may be possessed as R ^e, a hydroxyl group or an amino group.

  Although the specific example of a compound represented by Chemical formula (3) below is shown, it is not limited to these.

The addition amount of the organic acid represented by the general formula (3) is preferably 0.1% by mass or more and 5% by mass or less, and preferably 0.5% by mass or more and 2% by mass with respect to the mass of the polishing liquid used for polishing. % Or less is more preferable. That is, the content of such an organic acid is preferably 0.1% by mass or more from the viewpoint of achieving a sufficient polishing rate, and is preferably 5% by mass or less from the point of not causing excessive dishing.
You may contain 2 or more types of organic acids represented by General formula (3) in the polishing liquid for process (b).

<(B) pH of metal polishing slurry for process>
In the present invention, the metal polishing slurry used in step (b) has a pH of 2 or more, preferably in the range of pH 2 to 10, more preferably in the range of pH 5 to 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, etc. It can be set in consideration.
The pH can be adjusted, for example, by adding an alkali agent described later, or by adding an organic acid other than the compound represented by the general formula (3), a buffering agent, or the like.
(B) The end point of the process can be detected by the exposure of the barrier metal film, and since the barrier film serves as a stopper, the polishing liquid used in the process (b) is a conductor film such as Cu / Ta. / A barrier film having a large polishing rate ratio is preferred.

<Barrier layer polishing process>
In the present invention, the conductor film can be uniformly and efficiently polished through the steps (a) and (b).
Usually, after the barrier layer is exposed, the barrier layer is polished to expose the substrate, and the planarization of the semiconductor device provided with the same layer on the substrate is completed.
In the metal polishing liquid used for this barrier layer polishing process, from the viewpoint of polishing rate control, an organic acid having a chemical mechanical polishing rate of 50 nm / min or more, preferably 50 to nm / min with respect to the barrier layer. It is preferable to use together.
Examples of such an organic acid include organic acids having at least one carboxyl group in the molecule, and preferably a compound represented by the following general formula (4).
R-COOH (4)
In the general formula (4), R represents a hydrogen atom, a carboxyl group, or a hydrocarbon group, and the hydrocarbon group may be further substituted with a hydroxyl group, a carboxyl group, or a hydrocarbon group.

In the general formula (4), the hydrocarbon group represented by R may be saturated or unsaturated, may be chain-like, cyclic, or branched. Specific examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, and an alkenyl group.
This hydrocarbon group may have a substituent, and examples of the substituent that can be introduced include a hydroxyl group, a carboxyl group, and a hydrocarbon group.

  As such an organic acid, preferably benzoic acid, glycolic acid, salicylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, Examples include lactic acid.

The addition amount of the organic acid having a carboxyl group represented by the general formula (4) is preferably 0.1% by mass or more and 5% by mass or less based on the mass of the metal polishing liquid used for polishing the barrier layer. More preferably, the content is 5% by mass or more and 2% by mass or less. That is, the content of such an organic acid is preferably 0.1% by mass or more from the viewpoint of achieving a sufficient polishing rate, and is preferably 5% by mass or less from the point of not causing excessive dishing.
Two or more organic acids having at least one carboxyl group in the molecule may be contained in the slurry.

<PH of metal polishing slurry for barrier layer polishing step>
In the present invention, the pH of the metal polishing liquid used for polishing the barrier layer is 2 or more, preferably in the range of pH 2 to 10, more preferably in the range of pH 5 to 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, etc. It can be set in consideration.
The pH can be adjusted, for example, by adding an alkali agent described later, or by adding an organic acid other than the compound represented by the general formula (4), a buffering agent, or the like.

<Other components that can be contained in the polishing liquid>
[Heteroaromatic ring compound]
The (a) step polishing liquid, (b) step polishing liquid, and barrier layer polishing step polishing liquid used in the polishing method of the present invention are compounds that form a passive film on the metal surface to be polished. It is preferable to contain at least one heterocyclic compound.

Hereinafter, the heteroaromatic ring compound that can be used in the present invention will be described. 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, indolizine, indole, indazole, purine, quinolidine, isoquinoline, quinoline, naphthyridine, phthalazine, quinoxaline, quinazoline, cinnoline, pteridine, 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 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, 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 liquid for the step (a), the step (b) and the barrier layer polishing step 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.

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

(Chelating agent)
The metal polishing liquid according to 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.

(Alkaline agent, buffer agent)
Moreover, each said metal polishing liquid in this invention can contain a buffering agent from the point of the fluctuation | variation suppression of an alkali agent for pH adjustment as needed, as needed.

  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 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]
In the prior art, in order to polish the conductor layer at a high polishing rate, dishing and erosion occur due to excessive polishing of the conductor layer, or when polishing the conductor layer and the barrier layer, An electrochemical reaction proceeds between the conductor layer and the barrier layer, and the conductor layer is selectively polished. Therefore, there is a problem that dishing occurs.
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 with the surface on the conductor film side as a surface to be polished,
The conductive film is polished in at least two steps using the metal polishing liquid.

That is, the polishing method of the present invention comprises (a) chemical mechanical polishing of a conductor layer with a polishing liquid containing a compound represented by the general formula (1) or the general formula (2), an oxidizing agent, and abrasive grains. A step of polishing at a rate of 300 nm / min or more and an etching rate of 70 nm / min or more, that is, a step of polishing the conductor layer so that the polishing is completed before the barrier layer is exposed, and (b) the general formula (3) Polishing at a chemical mechanical polishing rate of 300 nm / min or less and an etching rate of 20 nm / min or less with respect to the conductor layer until a barrier layer is exposed with a polishing liquid containing a compound represented by And a second step of polishing the conductor layer until the barrier layer is exposed.
In addition, it is preferable to perform the process of grind | polishing a barrier layer further as mentioned above after completion | finish of (a) process and (b) process.

  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 so that the surface to be polished and the polishing pad are moved relative to each other (relatively moved). 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, 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 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 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 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 oxidizing agent is one component (A), an acid, an additive, a surfactant and water are one component (B), and when they are used, the component (A) 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.

  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 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 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, methylsilsesquioxane, and the like, and 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 of the present invention is more preferably a combination of the above preferred examples.
In the present invention, the thickness of the interlayer insulating film of the semiconductor device to be polished 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 of a semiconductor device to be polished in the present invention includes, for example, US Pat. Nos. 6,440,866, 6,410,463, and 6,596. Reference may be made to the specification of 654.

(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 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 5 to 30 nm.

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

[Step (a)]
<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: Rohm and Haas
Part No. 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.
By these, the film thickness of a copper pattern wafer was grind | polished to 80%, and it was set as the (a) process.

[Evaluation item]
(Polishing speed)
-Copper film-
The film thickness difference before and after CMP of copper, which is a conductor 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 measured by polishing rate (nm / min) = [(thickness of copper film before polishing) − (thickness of copper film after polishing)] / polishing time.
(Etching rate)
A copper-coated wafer (hereinafter referred to as a copper solid film wafer) was immersed for 1 minute in a metal abrasive that had been previously removed from the abrasive grains and adjusted to a temperature of 40 ° C., and the copper eluted in the abrasive. The amount (hereinafter referred to as etching amount) was quantified with an ICP emission spectrometer ICP-1000IV (manufactured by Shimadzu Corporation). Specifically, the film thickness of the dissolved copper was calculated from the etching amount according to the following formula, and used as the etching rate.
Formula: Etching rate (nm / min) = [(etching amount) / (abrasive liquid amount)] / (specific gravity of copper) / (area of sample wafer)

[(A) Preparation of metal polishing slurry for process]
-Heterocyclic compound: 0.01% by mass of benzotriazole
Component (i): Organic acid (compound described in Table 4) 0.254 mol / L
-Component (ii): Hydrogen peroxide 0.198 mol / L
-Component (iii): Colloidal silica 0.11 wt%
・ 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 prepare metal polishing liquids [a-1] to [a-4] shown in Table 4 below. Also, comparative polishing liquids [ax], [ay] and [az] containing no organic acid, abrasive particles or hydrogen peroxide were prepared. The polishing test was conducted using the metal polishing liquid.
Table 4 shows the polishing composition, the polishing rate in the step (a), and the etching rate.

[Step (b)]
<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: Rohm and Haas
Part No. IC-1400 (K-grv) + (A21)
・ Slurry supply rate: 200 ml / min

The object to be polished was polished until the Ta film (barrier metal film) was exposed using the device polished with the polishing liquid [a-1] in the step (a).
The polishing rate of the conductor film and the like was measured in the same manner as in the step (a).

[(B) Preparation of metal polishing slurry for process]
-Heterocyclic compound: benzotriazole 0.30% by mass
Component (iv): Organic acid (compound described in Table 5) 0.032 mol / L
-Component (ii): Hydrogen peroxide 0.198 mol / L
-Component (iii): Colloidal silica 0.11 wt%
・ PH (adjusted with ammonia water and sulfuric acid) 6.5
・ Pure water is added and the total volume is 1000mL

An aqueous solution is prepared so that each component has the above-mentioned concentration, stirred with a high-speed homogenizer, and uniformly dispersed to obtain the metal polishing liquids [b-1] to [b-4] as shown in Table 5 below. It was. Further, comparative polishing liquids [bx], [by], and [bz] containing no organic acid, abrasive particles or hydrogen peroxide were prepared, and the polishing test was performed under the above conditions.
Table 5 shows the polishing composition and the polishing rate and etching rate in step (b), measured in the same manner as in step (a).

  Polishing was performed at the indicated polishing rate by using the above-mentioned polishing liquid for step (a) and the polishing liquid for step (b) in combinations shown in Table 6 below. About each device which implemented the (a) process and the (b) process, barrier film grinding | polishing was performed on condition of the following.

[Barrier film polishing process]
In this step, both the example in which the step (a) and the step (b) were carried out and the comparative example in which any of the conditions was outside the scope of the present invention were targeted for polishing.
<Polishing conditions>
・ Polishing device: “LGP-612” manufactured by Lapmaster
・ Wafer: Pattern wafer with 8 inch copper film and Cu film polishing process ・ Table rotation speed: 50 rpm
-Head rotation speed: 50 rpm
・ Polishing pressure: 168 hPa
・ Polishing pad: Part number IC-1400 manufactured by Rodel Nitta Co., Ltd.
・ Slurry supply rate: 200 ml / min

<Metal polishing liquid for barrier film polishing process>
Heterocyclic compound: benzotriazole 0.10% by mass
・ Organic acid (glycolic acid) 0.15 mol / L
-Component (ii): Hydrogen peroxide 0.13 mol / L
-Component (iii): Colloidal silica 10 wt%
・ PH (adjusted with ammonia water and sulfuric acid) 2.5
・ Pure water is added and the total volume is 1000mL
An aqueous solution was prepared so that each component had the above-mentioned concentration, and stirred with a high-speed homogenizer and uniformly dispersed to obtain a metal polishing liquid for barrier film polishing. The above polishing test was conducted and evaluated using the metal polishing liquid.

[Evaluation item]
After polishing the barrier film, the following items were evaluated. The results are shown in Table 6 below.
(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).

(Erosion evaluation)
In addition to the time until the copper in the non-wiring portion is completely polished, a wafer polished for a time corresponding to 50% of the time was used for the pattern wafer (the erosion after this polishing is 9 μm / line). 30 nm in 1 μm space). Using this wafer, erosion (line 9 μm / space 1 μm) of the wafer polished for 30 seconds with each polishing liquid was measured with a scanning electron microscope S4800 (manufactured by Hitachi High-Technology Corporation).

As shown in Table 6, in Examples 1 to 7 according to the method of the present invention, excellent values were obtained for each polishing rate, dishing amount and erosion amount. For this reason, in the polishing method of the present invention, which is polished at the specified speed of the present invention using the polishing liquid as in Examples 1 to 3, the occurrence of dishing and erosion can be suppressed, and flattening can be performed satisfactorily. It can be seen that no scratches occur.
On the other hand, in Comparative Example 1, when a polishing liquid outside the range of the present invention was used in step (b), the dishing amount was extremely inferior and the erosion amount was not measurable. Moreover, in the comparative example 2 using the polishing liquid outside the scope of the present invention in the step (a), the copper pattern wafer could not be polished sufficiently, and therefore the dishing amount and erosion amount could not be measured.

Claims (3)

A polishing method for flattening a semiconductor device having a conductor film containing copper as a main component, wherein the conductor film is subjected to a polishing step including the following steps (a) and (b).
(A) In a polishing liquid containing a compound represented by the following general formula (1) or general formula (2), an oxidizing agent and abrasive grains, a chemical mechanical polishing rate of 300 nm / min or more with respect to the conductor layer, and Polishing at an etching rate of 70 nm / min or more,

In the general formula (1) and the general formula (2), R ¹ and R ⁶ each independently represents a single bond, an alkylene group, or a phenylene group.
R ² , R ³ , R ⁷ and R ⁸ each independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ⁴ represents a hydrogen atom, a halogen atom, an alkyl group or an acyl group. R ⁵ and R ⁹ represent an alkylene group, and R ¹⁰ represents a single bond, an alkylene group, an alkyleneoxy group, or a phenylene group. However, when R ⁵ is —CH ₂ —, R ¹ is an alkylene group or a phenyl group, and / or R ⁴ is any one of a halogen atom and an alkyl group, and R ⁹ is —CH ₂ —. R ⁶ is an alkylene group or a phenyl group, and / or R ¹⁰ is any one of an alkylene group, an alkyleneoxy group, or a phenylene group.
(B) In a polishing liquid containing a compound represented by the following general formula (3), an oxidizing agent and abrasive grains, a chemical mechanical polishing rate of 300 nm / min or less and an etching rate of 20 nm / min or less with respect to the conductor layer. The process of polishing with.

In the general formula (3), R ^a represents a single bond, an alkylene group, or a phenylene group.
R ^b and R ^c each independently represents a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group.
R ^d and R ^e each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an acyl group.
However, when R ^a is a single bond, at least one of R ^d and R ^e is not a hydrogen atom.   In the step (a) and the step (b), the oxidizing agent contained in the polishing liquid is a hydrogen peroxide solution, and a polishing liquid having a concentration of 0.01 to 1.5 mol / L is used. The method for polishing a semiconductor device according to claim 1.   2. The polishing liquid according to claim 1, wherein in the steps (a) and (b), the abrasive contained in the polishing liquid is silica particles, and the concentration thereof is 0.0001 to 5 wt%. Polishing method for semiconductor devices.