JP2017122134A - Polishing liquid for metal film and polishing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing liquid for metal film high in surface smoothness of a surface to be polished with suppressing dishing while suppressing erosion between wires with maintaining good polishing speed to an interlayer insulation film, and a polishing method using the same.SOLUTION: There is provided a polishing liquid for metal film containing polishing particles, a methacrylic acid-based polymer having weight average molecular weight of 20,000 or more and an aqueous solvent. There is provided a polishing liquid, wherein the aqueous solvent consists of water or water and acid and the polishing liquid for metal film is for chemical mechanical polishing a substrate generating a residue of a conductive material in a peripheral part of a metal wire and no residue in a part between the metal wires.SELECTED DRAWING: None

Description

  The present invention relates to a metal film polishing liquid and a polishing method using the same. Specifically, the present invention relates to a metal film polishing liquid used for polishing in a wiring formation process or the like of a semiconductor device and a polishing method using the metal film polishing liquid.

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (hereinafter referred to as LSIs). A chemical mechanical polishing (hereinafter referred to as CMP) method is one of them, and a technique frequently used in the planarization of an interlayer insulating film, the formation of a metal plug, and the formation of a buried wiring in an LSI manufacturing process, particularly a multilayer wiring forming process. It is. This technique is disclosed in, for example, US Pat. No. 4,944,836 (Patent Document 1).

  Recently, in order to improve the performance of LSIs, attempts have been made to use copper and copper alloys as conductive materials serving as wiring materials. However, it is difficult to finely process copper or a copper alloy by a dry etching method frequently used in forming a conventional aluminum alloy wiring.

  Therefore, a so-called damascene method is mainly employed in which a thin film of copper or copper alloy is deposited and embedded on an insulating film in which a groove is formed in advance, and the above-mentioned thin film other than the groove is removed by CMP to form a buried wiring. ing. This technique is disclosed, for example, in JP-A-2-278822 (Patent Document 2).

  A general method of metal CMP for polishing metal wiring such as copper or copper alloy is to apply a polishing cloth (pad) on a circular polishing platen (platen) and immerse the surface of the polishing cloth with a polishing solution for metal film. While pressing the surface of the substrate on which the metal film was formed against the surface of the polishing cloth, rotating the polishing platen while applying a predetermined pressure (hereinafter referred to as polishing pressure) from the back surface of the polishing cloth to the metal film, polishing The metal film on the convex portion is removed by relative mechanical friction between the liquid and the convex portion of the metal film.

  The metal film polishing liquid used in CMP is generally composed of an oxidant, abrasive particles, and water, and a metal oxide solubilizer, a protective film forming agent, and the like are further added as necessary. It is considered that the basic mechanism is to first oxidize the surface of the metal film with an oxidizing agent to form an oxide layer, and then scrape the oxide layer with abrasive particles. The oxide layer on the surface of the metal film in the recess does not touch the polishing pad so much, and the effect of scraping off by the abrasive particles does not reach, so the oxide layer on the metal film in the convex portion is removed and the substrate surface is flattened with the progress of CMP. . The details are disclosed in Journal of Electrochemical Society, Vol. 138, No. 11 (issued in 1991), pages 3460 to 3464 (Non-patent Document 1).

  As a method for increasing the polishing rate by CMP, it is effective to add a metal oxide dissolving agent to the metal film polishing liquid. It is interpreted that if the metal oxide particles scraped by the abrasive particles are dissolved in the polishing liquid (hereinafter referred to as etching), the effect of scraping by the abrasive particles is increased. Although the polishing rate by CMP is improved by adding a metal oxide solubilizer, on the other hand, when the oxide layer on the metal film surface in the recess is also etched to expose the metal film surface, the metal film surface is further oxidized by the oxidant and this is repeated. As a result, the etching of the metal film in the recesses proceeds. For this reason, a phenomenon occurs in which the central portion of the surface of the metal wiring embedded after polishing is depressed like a dish (hereinafter referred to as dishing), and the planarization effect is impaired.

  In order to prevent this, a protective film forming agent is further added to the metal film polishing liquid. The protective film forming agent forms a protective film on the oxide layer on the surface of the metal film and prevents the oxide layer from being etched. This protective film can be easily scraped off by abrasive particles, and it is desirable not to decrease the polishing rate by CMP.

  For metal films containing aminoacetic acid or amide sulfuric acid such as glycine as a metal oxide solubilizing agent and benzotriazole as a protective film forming agent to suppress dishing and etching of the metal film and form highly reliable LSI wiring A method using a polishing liquid has been proposed. This technique is described, for example, in JP-A-8-83780 (Patent Document 3).

  In metal buried formation such as damascene wiring formation such as copper or copper alloy or plug wiring formation such as tungsten, if the polishing rate of the interlayer insulating film formed other than the embedded portion is high, the interlayer insulation between the wirings A phenomenon that the thickness of the film becomes thin (hereinafter referred to as inter-wiring erosion) occurs and flatness deteriorates. As a result, problems such as an increase in wiring resistance occur, so that erosion between wirings is required to be as small as possible.

  On the other hand, under the metal wiring such as copper or copper alloy, tantalum, tantalum alloy, as a barrier conductor layer (hereinafter referred to as a barrier layer) for preventing metal diffusion into the interlayer insulating film and improving adhesion. A layer made of a conductor such as tantalum nitride is formed. Therefore, it is necessary to remove the exposed barrier layer by CMP except for the wiring portion in which metal wiring such as copper or copper alloy is embedded. However, since the conductors of these barrier layers are higher in hardness than copper or copper alloys, a sufficient polishing rate cannot be obtained even when a polishing material for copper or copper alloys is combined, and the surface to be polished is flat. Is often worse. In view of this, a two-stage polishing method comprising a first polishing step for polishing a metal wiring and a second polishing step for polishing a barrier layer has been studied.

  FIG. 1 is a schematic cross-sectional view showing wiring formation by a general damascene process. FIG. 1A shows a state before polishing, an interlayer insulating film 1 having grooves formed on the surface, a barrier layer 2 formed so as to follow the surface irregularities of the interlayer insulating film 1, and deposited so as to fill the irregularities. The copper or copper alloy metal wiring layer 3 is provided.

  First, as shown in FIG. 1B, the metal wiring layer 3 is polished with a polishing liquid for polishing metal wiring until the barrier layer 2 is exposed. Next, as shown in FIG. 1C, polishing is performed with a polishing liquid for polishing the barrier layer until the convex portions of the interlayer insulating film 1 are exposed.

  As such a polishing liquid for polishing the barrier layer, it contains an oxidizing agent, a protective film forming agent for the metal surface, an acid, and water, has a pH of 3 or less, and a concentration of the oxidizing agent of 0.01 to An abrasive for chemical mechanical polishing of 3% by mass has been proposed (see, for example, Republished Patent No. 01/13417 (Patent Document 4)).

In the above-described two-stage polishing method, after the first polishing step of polishing the metal wiring layer 3 with a polishing liquid for metal wiring polishing, a residue of a conductive substance may be generated in the peripheral portion of the metal wiring. For example, when a polishing liquid containing ammonium persulfate (ammonium peroxodisulfate) as an oxidizing agent is used in the first polishing step, the residue of the conductive material appears remarkably (see, for example, JP-A-2007-335531 (Patent Document) 5)).
This conductive material residue does not occur in the upper part of the portion between the metal wiring (for example, the portion between the conductive material and the conductive material in FIG. 2B), and there is no metal wiring around. There is a state in which a residue of the conductive material is generated in the portion of the field that does not exist.
In the above-described two-stage polishing method, in the second polishing step for polishing the barrier layer, an over-polishing step of polishing the interlayer insulating film excessively may be required in order to flatten the surface to be polished. Examples of the interlayer insulating film include silicon dioxide, organosilicate glass which is a low-k (low dielectric constant) film, and a wholly aromatic ring-based low-k film.

U.S. Pat. No. 4,944,836 JP-A-2-278822 JP-A-8-83780 Republished Patent No. 01/13417 JP 2007-335531 A

Journal of Electrochemical Society, Vol.138, No.11 (1991), 3460-3464

After the first polishing step for polishing the metal wiring layer 3 as shown in FIG. 2A, a conductive material residue is generated in the periphery of the metal wiring as shown in FIG. 2B. When the barrier layer is polished in the second polishing step using a substrate in which no residue is generated between the metal wiring and the metal wiring, the portion of the field where there is no metal wiring in the periphery is conductive. As shown in FIG. 2C, the progress of the polishing of the barrier layer is delayed because of the residue of the active substance, but the barrier layer is polished at the same time as the polishing starts at the portion between the metal wiring and the metal wiring. Inter-wiring erosion occurs in which the portion between the metal wiring and the metal wiring is excessively polished.
Therefore, by using a large amount of oxidizing agent in the polishing liquid used in the second polishing process for polishing the barrier layer, it is possible to quickly remove the residue of the conductive material in the field portion and reduce erosion between the wirings. It is. However, when the polishing liquid is used, the polishing rate of the metal wiring also increases, and there is a problem that dishing is further increased.
In view of the above problems, the present invention provides a metal film polishing liquid with high flatness of a surface to be polished that suppresses the occurrence of erosion between wirings while maintaining a good polishing rate for an interlayer insulating film and also suppresses dishing. And a polishing method using the same.

In order to suppress dishing while reducing the above-mentioned erosion between the wirings, the present inventors have a high polishing rate with respect to the residue of the conductive material in the field part, but there are dents like the metal wiring part. The inventors have conceived that it is effective to use an additive having a low polishing rate for a metal wiring portion, and found that this can be achieved when a specific polymer is used as an additive.
That is, the present invention relates to (1) a polishing slurry for metal films, comprising abrasive particles, a methacrylic acid polymer having a weight average molecular weight of 20,000 or more, and an aqueous solvent.

The present invention also relates to (2) the metal film polishing liquid according to (1) above, wherein the aqueous solvent comprises water or water and an acid.
Further, the present invention provides: (3) A substrate in which the metal film polishing liquid generates a residue of a conductive material in a peripheral portion of the metal wiring and does not generate a residue in a portion between the metal wiring and the metal wiring. The metal film polishing liquid according to (1) or (2) above, which is a polishing liquid for chemical mechanical polishing.
Further, the present invention provides (4) wherein the methacrylic acid polymer is at least one selected from a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid. It is related with the polishing liquid for metal films as described in any one of-(3).

The present invention also provides (5) the above (1) to (4), wherein the abrasive particles contain at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. The polishing liquid for metal films as described in any one of 1).
The present invention also relates to (6) the metal film polishing liquid according to any one of (1) to (5) above, further comprising a compound having a triazole skeleton as a metal anticorrosive.

  Moreover, this invention relates to the polishing liquid for metal films as described in any one of said (1)-(6) which further contains (7) organic solvent.

  The present invention also relates to (8) the metal film polishing liquid according to any one of (1) to (7), further comprising a metal oxidant.

  Moreover, this invention is (9) Polishing liquid for metal films as described in any one of said (1)-(8) which set pH of the said polishing liquid for metal films to 2.0-3.5. About.

  Moreover, this invention mixes the 1st liquid containing the said abrasive particle, the said methacrylic acid type polymer, the said aqueous solvent, and the said metal anticorrosive agent, and the 2nd liquid containing the said oxidizing agent. The metal film polishing liquid according to (8) or (9), wherein the metal film polishing liquid is obtained.

In addition, the present invention provides (11) an interlayer insulating film having a concave portion and a convex surface, a barrier layer that covers the interlayer insulating film along the surface, and a conductive layer that fills the concave portion and covers the barrier layer. A first polishing step of polishing a conductive material layer of a substrate having a material layer to expose the barrier layer of the convex portion;
The barrier layer of the substrate exposed in the first polishing step is polished using the metal film polishing liquid according to any one of (1) to (10) to form an interlayer insulating film of the convex portion. It is related with the grinding | polishing method characterized by including the 2nd grinding | polishing process to expose.

Further, the polishing method of the present invention is preferably a substrate having a wiring forming portion in which the wiring density of wiring formed by polishing the conductive material layer covering the barrier layer is 50% or more.
In the polishing method of the present invention, the interlayer insulating film is preferably a silicon-based film or an organic polymer film.

In the polishing method of the present invention, it is preferable that the conductive material contains copper as a main component.

  In the polishing method of the present invention, it is preferable that the barrier layer contains at least one selected from tantalum, a tantalum compound, titanium, a titanium compound, tungsten, a tungsten compound, ruthenium, a ruthenium compound cobalt, and a cobalt compound.

  According to the present invention, by containing a methacrylic acid polymer having a weight average molecular weight of 20,000 or more, a conductive material residue is generated while maintaining a good polishing rate for the interlayer insulating film, and metal wiring and When polishing the barrier layer of the substrate where no residue is generated between the metal wirings, the metal film polishing liquid with high flatness of the surface to be polished that suppresses the occurrence of erosion between the wirings and suppresses dishing. And a polishing method using the same.

  Further, according to the present invention, by including abrasive particles, metal oxidizer, metal anticorrosive, etc., in addition to the above effects, a good polishing rate for metal wiring and barrier metal can be obtained, Thus, a metal film polishing liquid suitable for the second polishing step can be obtained.

FIG. 1 is a schematic cross-sectional view relating to wiring formation by a damascene process. FIG. 2 is a schematic cross-sectional view showing a pattern portion in which a metal wiring portion and an interlayer insulating film portion of a pattern substrate with copper wiring are arranged, a metal residue for wiring, and erosion between wirings. FIG. 3 is a schematic cross-sectional view showing a pattern portion having a copper wiring of 70 μm and an interlayer insulating film of 30 μm polished in the first polishing step and the second polishing step.

  The metal film polishing liquid of the present invention contains a methacrylic acid polymer having a weight average molecular weight of 20,000 or more. A methacrylic acid polymer having a weight average molecular weight of 20,000 or more forms a fragile copper reaction layer as compared with a polymer having a weight average molecular weight of less than 20,000, and therefore has a high polishing rate and contains a large amount of an oxidizing agent. Since the dishing is suppressed as compared with the polishing liquid, it is estimated that the dishing can be reduced while suppressing the erosion between the wirings. The methacrylic acid polymer is preferably at least one selected from a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid.

  In this specification, the term “process” includes not only an independent process but also a process that cannot be clearly distinguished from other processes and in which the intended purpose can be achieved. . Moreover, the numerical range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Further, the content of each component in the polishing liquid means the total amount of the plurality of substances present in the polishing liquid unless there is a specific notice when there are a plurality of substances corresponding to each component in the polishing liquid.

  Hereinafter, preferred embodiments of the metal film polishing liquid of the present invention (hereinafter also simply referred to as “polishing liquid”) and a method for polishing a substrate using the metal film polishing liquid will be described in detail.

[Metal film polishing liquid]
The metal film polishing liquid of this embodiment is characterized by containing a methacrylic acid polymer having a weight average molecular weight of 20,000 or more and an aqueous solvent. The production method includes a step of polymerizing a monomer component containing at least methacrylic acid in a solution to obtain a methacrylic acid polymer having a weight average molecular weight of 20,000 or more, and a methacrylic acid polymer having a weight average molecular weight of 20,000 or more. And a step of mixing an aqueous solvent and abrasive particles to obtain a polishing liquid.

  The operations of “polymerization” and “mixing” in each step can be appropriately performed by those skilled in the art. Therefore, the compounds defined in each step will be described in detail in the next section “Polishing liquid”.

[Polishing liquid]
The polishing liquid of this embodiment contains a methacrylic acid polymer having a weight average molecular weight of 20,000 or more, abrasive particles, and an aqueous solvent. Such a polishing liquid can be suitably used for chemical mechanical polishing a substrate containing a residue of a conductive substance.

<Methacrylic acid polymer>
The methacrylic acid polymer of this embodiment has two methods, a case where a water-soluble polymerization initiator is used and a case where a polymerization initiator dissolved in a monomer component containing methacrylic acid is used. When using the latter polymerization initiator that dissolves in the monomer component containing methacrylic acid, first dissolve the polymerization initiator in the monomer component containing methacrylic acid, and then dissolve the polymerization initiator in an aqueous solvent. By adding dropwise a monomer component containing methacrylic acid, a polymer can be obtained while dissolving the polymerization initiator in an aqueous solvent.

  The methacrylic acid polymer is preferably at least one selected from a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid.

  When the methacrylic acid polymer is a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid, the ratio of methacrylic acid to the total amount of the monomer is preferably 40 mol% or more and less than 100 mol%, more preferably 50 mol. % Or more and less than 100 mol%, more preferably 60 mol% or more and less than 100 mol%, particularly preferably 70 mol% or more and less than 100 mol%. By setting the ratio of the methacrylic acid to 40 mol% or more, generation of erosion between wirings can be effectively suppressed, and the flatness of the surface to be polished can be easily improved.

  The weight average molecular weight of the methacrylic acid polymer is 20,000 or more, preferably 50,000 or more. Using a polishing liquid containing a polymer having a weight average molecular weight of 20,000 or more of the methacrylic acid polymer, a residue of the conductive material is generated, and a residue is generated between the metal wiring and the metal wiring. When polishing a barrier layer of a substrate that has not been processed, generation of erosion between wirings can be effectively suppressed, and the flatness of the surface to be polished can be easily improved. The upper limit of the weight average molecular weight is not particularly defined, but is preferably 5 million or less from the viewpoint of solubility. Further, from the viewpoint of ease of synthesis, ease of molecular weight control, etc., the upper weight average molecular weight is preferably 1,000,000 or less, from the viewpoint of excellent solubility in water and increasing the degree of freedom of addition. More preferably, it is 1,000 or less.

The weight average molecular weight of the methacrylic acid polymer can be measured by gel permeation chromatography using a standard polystyrene calibration curve. Specifically, for example, measurement can be performed by size exclusion chromatography using a calibration curve prepared with a sodium polyacrylate standard substance manufactured by Polymer Laboratories under the following measurement conditions.
Column: Shodex Asahipak GS-520HQ + 620HQ manufactured by Showa Denko KK
Pump: Hitachi Ltd. L-71000
_{Eluent: 50mM-Na 2 HPO 4 aq} . / CH ₃ CN = 90/10
Flow rate: 0.6 mL / min
Detector: L-3300 type differential refractometer manufactured by Hitachi, Ltd. Data processing: D-2520 type GPC indexer manufactured by Hitachi, Ltd. Sample concentration: 10 mg / mL
Injection volume: 5 μL

  Monomers copolymerizable with methacrylic acid include acrylic acid, crotonic acid, vinyl acetic acid, tiglic acid, 2-trifluoromethyl acrylic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, mesaconic acid, gluconic acid, etc. Carboxylic acids such as 2-acrylamido-2-methylpropane sulfonic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid And acrylic acid esters such as propyl acid, butyl methacrylate and 2-ethylhexyl methacrylate; and salts such as ammonium salts, alkali metal salts and alkylamine salts thereof. In the case where the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, acid or its ammonium salt is preferable because contamination with an alkali metal is not desirable. This is not the case when the substrate is a glass substrate or the like.

  As described above, a higher content of methacrylic acid in the methacrylic acid polymer is effective in reducing the occurrence of erosion between wirings.

  The blending amount of the methacrylic acid polymer is preferably 0.001 to 15 g, more preferably 0.01 to 5 g, when the total amount of all components of the polishing liquid is 100 g. By making the blending amount of the methacrylic acid-based polymer 0.001 g or more, the occurrence of erosion between wirings can be effectively suppressed, and the flatness of the surface to be polished can be easily improved. While suppressing the occurrence of erosion, the stability of the abrasive particles contained in the polishing liquid is maintained, and the dispersibility of the abrasive particles is easily improved.

<Abrasive particles>
The metal film polishing liquid of the present embodiment preferably contains abrasive particles from the viewpoint of obtaining a good polishing rate for the barrier layer and the interlayer insulating film. The abrasive particles that can be used are at least one selected from silica, alumina, zirconia, ceria, titania, germania, and modified products thereof. The modified product is obtained by modifying the surface of abrasive particles such as silica, alumina, zirconia, ceria, titania and germania with an alkyl group.

  The method for modifying the surface of the abrasive particles with an alkyl group is not particularly limited, and examples thereof include a method of reacting a hydroxyl group present on the surface of the abrasive particle with an alkoxysilane having an alkyl group. The alkoxysilane having an alkyl group is not particularly limited, but monomethyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, monoethyltrimethoxysilane, diethyldimethoxysilane, triethylmonomethoxysilane, monomethyltriethoxysilane, dimethyl Examples include diethoxysilane and trimethylmonoethoxysilane. The reaction method is not particularly limited. For example, the reaction is performed even when a polishing liquid containing abrasive particles and alkoxysilane is placed at room temperature, but the reaction may be heated to accelerate the reaction.

  Among the above-mentioned abrasive particles, colloidal silica and colloidal alumina having a good dispersion stability in the polishing liquid, a small number of polishing scratches (scratches) generated by CMP, and an average particle diameter of 200 nm or less are preferable. Colloidal silica and colloidal alumina having a diameter of 120 nm or less are more preferable.

  The “average particle diameter” of the abrasive particles means the average secondary particle diameter of the abrasive particles. The average particle diameter is a value of D50 (median diameter of volume distribution, cumulative median value) obtained by measuring the polishing liquid with a dynamic light scattering particle size distribution meter (for example, product name: COULTER Electronics 4 manufactured by COULTER Electronics). Say.

  Specifically, the average particle diameter can be measured by the following procedure. First, 100 μL of polishing liquid (L represents liter; the same applies hereinafter) is weighed, and the content of abrasive particles is around 0.05% by mass (the transmittance (H) during measurement is 60 to 70%). ) To obtain a diluted solution. And an average particle diameter can be measured by throwing a dilution liquid into the sample tank of a dynamic light scattering type particle size distribution analyzer, and reading the value displayed as D50.

  In addition, from the viewpoint of the polishing rate of the metal wiring film, barrier metal film, and interlayer insulating film, the abrasive particles are preferably particles in which primary particles are aggregated less than an average of less than 2 particles, and primary particles are less than an average of less than 1.2 particles. More preferred are non-aggregated particles. The upper limit of the degree of association differs depending on the primary particle size of the abrasive particles used, and it is considered that the secondary particle size only needs to be in the range described above. The degree of association can be obtained as the ratio (secondary particle diameter / primary particle diameter) by determining the secondary particle diameter and the primary particle diameter.

  As a measuring method of the said primary particle diameter, it can measure with a well-known transmission electron microscope (for example, H-7100FA by Hitachi, Ltd.). For example, using the electron microscope, an image of particles is taken, a biaxial average primary particle diameter is calculated for a predetermined number of arbitrary particles, and an average value thereof is obtained. When the particle size distribution is wide, the predetermined number should be a quantity whose average value is stable. When colloidal silica or colloidal alumina is used as the abrasive particles, since the particle diameter is generally uniform, the number of particles to be measured may be about 20 particles, for example.

  Specifically, a rectangle (circumscribed rectangle) that circumscribes the selected particle and is arranged so that its major axis is the longest is derived. Then, assuming that the major axis of the circumscribed rectangle is L and the minor axis is B, the biaxial average primary particle diameter of one particle is calculated as (L + B) / 2. This operation is performed on 20 arbitrary particles, and the average value obtained is referred to as a biaxial average primary particle diameter (R1) in the present embodiment. This operation can also be automated by a computer program.

  At the same time, the standard deviation of the average particle size distribution is preferably 10 nm or less, and the standard deviation of the average particle size distribution is more preferably 5 nm or less. As a method for measuring the standard deviation of the particle size distribution, the abrasive particles in the polishing liquid can be put into COULTER N4SD manufactured by COULTER Electronics, and the standard deviation value can be obtained from the particle size distribution chart.

  The blending amount of the abrasive particles is preferably 0.01 to 50 g, more preferably 0.02 to 30 g, and particularly preferably 0.05 to 20 g with respect to 100 g of the total amount of all components of the polishing liquid. By making the blending amount of the abrasive particles 0.01 g or more, the polishing rate is improved, and by making it 50 g or less, it becomes easy to suppress the generation of scratches.

  As the abrasive particles, abrasive particles obtained by modifying the surface of the abrasive particles with an anionic group or a cationic group may be used. By modifying the anion group or the cation group, the surface potential of the abrasive particles becomes negative or positive charge, so that aggregation of the abrasive particles due to pH change of the polishing liquid can be suppressed.

  Examples of the anionic group to be modified include sulfonic acid modification and aluminate modification. Examples of the cationic group to be modified include amine compounds.

<Aqueous solvent acid>
The metal film polishing liquid of the present invention preferably contains an acid in that the metal wiring oxidized by the oxidizing agent and the barrier metal can be accelerated and the polishing rate can be improved. The acid used in the present invention is not particularly limited as long as the oxidized barrier metal or metal wiring can be dissolved in water. For example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n -Hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, Salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, 3-methylphthalic acid, 4-methylphthalic acid, 3-aminophthalic acid, 4-aminophthalic acid, 3-nitrophthalic acid, 4-nitrophthalic acid, glutaric acid, adipic acid, Pimelic acid, maleic acid, phthalic acid, isophthalic acid, malic acid, tartaric acid, citric acid, p-toluenesulfonic acid, p-phenolsulfone , Methylsulfonic acid, lactic acid, itaconic acid, benzoic acid, maleic acid, quinaldic acid, adipic acid, pimelic acid, and other organic acids, organic acid esters thereof and ammonium salts of these organic acids, alkali metals, alkaline earth metals, And salts with halides and the like. Further, inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, ammonium salts of these inorganic acids, ammonium persulfate, ammonium nitrate, ammonium chloride, chromic acid and the like can be mentioned. However, for example, when the substrate to be polished is a silicon substrate including an integrated circuit element, contamination by alkali metal, alkaline earth metal, halide, etc. is not desirable. Or a salt other than a salt with a halide is preferred. Among these, malonic acid, malic acid, tartaric acid, citric acid, salicylic acid, adipic acid, phthalic acid, glycolic acid, succinic acid in that the etching rate can be effectively suppressed while maintaining a practical polishing rate. It is preferably at least one selected from Moreover, these can be used individually by 1 type or in mixture of 2 or more types.

  The compounding amount of the acid is preferably 0.001 to 20 g, more preferably 0.002 to 10 g, and still more preferably 0.005 to 5 g with respect to 100 g of the total amount of all components of the metal film polishing liquid. When the amount of the acid is 0.001 g or more, the polishing rate of the metal wiring and the barrier metal is improved, and when the amount is 20 g or less, etching is suppressed and the roughness of the surface to be polished is easily reduced.

  The polishing liquid of this embodiment can also be obtained by mixing two liquids divided into a slurry containing at least abrasive particles and an additive liquid containing at least a methacrylic acid polymer. By doing so, it is possible to avoid the problem of stability of the abrasive particles which occurs when a large amount of methacrylic acid polymer is added. When dividing into two liquids, a methacrylic acid polymer may be contained on the slurry side. In this case, the content of the methacrylic acid polymer in the slurry is in a range that does not impair the dispersibility of the abrasive particles.

<Metal anticorrosive>
The metal film polishing liquid of the present embodiment may further contain a metal anticorrosive. There is no restriction | limiting in particular as a metal anticorrosive agent, Any conventionally well-known thing can be used as a compound which has the anticorrosion action with respect to a metal. Specifically, at least one selected from triazole compounds, pyridine compounds, pyrazole compounds, pyrimidine compounds, imidazole compounds, guanidine compounds, thiazole compounds, tetrazole compounds, triazine compounds, and hexamethylenetetramine can be used. Here, “compound” is a general term for compounds having the skeleton, and for example, a triazole compound means a compound having a triazole skeleton. A triazole compound having a triazole skeleton is preferable as the metal anticorrosive used in the metal film polishing liquid of the present invention.

  Examples of the triazole compound include 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, benzotriazole, 1-hydroxy. Benzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxy-1H-benzotriazole, 4- Carboxy-1H-benzotriazole-methyl ester (methyl 1H-benzotriazole-4-carboxylate), 4-carboxy-1H-benzotriazole-butyl ester (butyl 1H-benzotriazole-4-carboxylate), 4-carboxy- 1H-benzotriazol-octyl ester (1H-benzotriazole-4-carboxylic acid oct ), 5-hexylbenzotriazol, (1,2,3-benzotriazolyl-1-methyl) (1,2,4-triazolyl-1-methyl) (2-ethylhexyl) amine, tolyltriazo- , Naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid, 3H-1,2,3-triazolo [4,5-b] pyridin-3-ol, 1H-1,2,3 -Triazolo [4,5-b] pyridine, 1-acetyl-1H-1,2,3-triazolo [4,5-b] pyridine, 3-hydroxypyridine, 1,2,4-triazolo [1,5- a] pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido [1,2-a] pyrimidine, 2-methyl-5,7-diphenyl- [1,2,4] triazolo [1 , 5-a] pyrimidine, 2-me Rusulfanyl-5,7-diphenyl- [1,2,4] triazolo [1,5-a] pyrimidine, 2-methylsulfanyl-5,7-diphenyl-4,7-dihydro- [1,2,4] And triazolo [1,5-a] pyrimidine. In addition, when it has a triazole skeleton and other skeletons in one molecule, it shall be classified as a triazole compound.

  Examples of the pyridine compound include 8-hydroxyquinoline, prothionamide, 2-nitropyrin-3-ol, pyridoxamine, nicotinamide, iproniazide, isonicotinic acid, benzo [f] quinoline, 2,5-pyridinedicarboxylic acid, 4-styryl. Pyridine, anabasine, 4-nitropyridine-1-oxide, pyridine-3-ethyl acetate, quinoline, 2-ethylpyridine, quinolinic acid, arecoline, citrazic acid, pyridine-3-methanol, 2-methyl-5-ethylpyridine, Examples include 2-fluoropyridine, pentafluoropyridine, 6-methylpyridin-3-ol, and pyridine-2-ethyl acetate.

  Examples of the pyrazole compound include pyrazole, 1-allyl-3,5-dimethylpyrazole, 3,5-di (2-pyridyl) pyrazole, 3,5-diisopropylpyrazole, 3,5-dimethyl-1-hydroxymethylpyrazole. 3,5-dimethyl-1-phenylpyrazole, 3,5-dimethylpyrazole, 3-amino-5-hydroxypyrazole, 4-methylpyrazole, N-methylpyrazole, 3-aminopyrazole, 3-aminopyrazole .

  Pyrimidine compounds include pyrimidine, 1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2, 4,5-trihydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4 -Diamino-6-hydroxylpyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, 4-aminopyrazolo [3,4-d] pyrimidine and the like.

  Examples of the imidazole compound include 1,1′-carbonylbis-1H-imidazole, 1,1′-oxalyldiimidazole, 1,2,4,5-tetramethylimidazole, and 1,2-dimethyl-5-nitroimidazole. 1,2-dimethylimidazole, 1- (3-aminopropyl) imidazole, 1-butylimidazole, 1-ethylimidazole, 1-methylimidazole and benzimidazole.

  Examples of the guanidine compound include 1,1,3,3-tetramethylguanidine, 1,2,3-triphenylguanidine, 1,3-di-o-tolylguanidine, and 1,3-diphenylguanidine.

  Examples of the thiazole compound include 2-mercaptobenzothiazole and 2,4-dimethylthiazole.

  Examples of the tetrazole compound include tetrazole, 5-methyltetrazole, 5-amino-1H-tetrazole, and 1- (2-dimethylaminoethyl) -5-mercaptotetrazole.

  Examples of the triazine compound include 3,4-dihydro-3-hydroxy-4-oxo-1,2,4-triazine.

  The said metal anticorrosive can be used individually by 1 type or in mixture of 2 or more types. The content of the metal anticorrosive is preferably 0.001% by mass to 10% by mass with respect to the total mass of the polishing liquid in that a good polishing rate can be obtained for the film to be polished. From the same viewpoint, the content of the metal anticorrosive is more preferably 0.01% by mass or more, and further preferably 0.02% by mass or more. Further, from the same viewpoint, the content of the metal anticorrosive is more preferably 5.0% by mass or less, and further preferably 0.5% by mass.

  The metal anticorrosive agent forms a protective film on a metal wiring such as a copper-based metal, thereby suppressing the etching of the metal wiring and easily reducing the roughness of the surface to be polished.

  From such a viewpoint, at least one selected from the group consisting of a triazole compound, a pyridine compound, an imidazole compound, a tetrazole compound, a triazine compound, and hexamethylenetetramine is preferable among the metal anticorrosive agents. Triazole compounds such as 3-triazolo [4,5-b] pyridin-3-ol, 1-hydroxybenzotriazole, 1H-1,2,3-triazolo [4,5-b] pyridine, benzotriazole, 3-hydroxy More preferred is at least one selected from the group consisting of pyridine, benzimidazole, 5-amino-1H-tetrazole, 3,4-dihydro-3-hydroxy-4-oxo-1,2,4-triazine and hexamethylenetetramine. .

  The ratio of the acid and the metal anticorrosive agent (acid / metal anticorrosive agent) in the polishing liquid is in the range of 10/1 to 1/5 in terms of mass ratio from the viewpoint of favorably controlling the etching rate and the polishing rate. The range of 7/1 to 1/5 is more preferable, the range of 5/1 to 1/5 is more preferable, and the range of 5/1 to 1/1 is particularly preferable.

  Further, the metal film polishing liquid is selected from the group consisting of a carboxylic acid compound, a triazole compound, a pyridine compound, an imidazole compound, a tetrazole compound, a triazine compound, and hexamethylenetetramine from the viewpoint of favorably controlling the etching rate and the polishing rate. It is preferable that the ratio (carboxylic acid compound / metal anticorrosive) to at least one metal anticorrosive to be 10/1 to 1/5, the carboxylic acid compound, triazole compound, pyridine compound, imidazole compound, It is more preferable that the ratio (carboxylic acid compound / metal anticorrosive) to at least one metal anticorrosive selected from the group consisting of a tetrazole compound, a triazine compound and hexamethylenetetramine is 5/1 to 1/5, The carboxylic acid compound and 3H-1,2,3-to Triazol compounds such as azolo [4,5-b] pyridin-3-ol, 1-hydroxybenzotriazole, 1H-1,2,3-triazolo [4,5-b] pyridine, benzotriazole, 3-hydroxypyridine, At least one metal corrosion inhibitor selected from the group consisting of benzimidazole, 5-amino-1H-tetrazole, 3,4-dihydro-3-hydroxy-4-oxo-1,2,4-triazine and hexamethylenetetramine; The ratio (carboxylic acid compound / metal anticorrosive) is more preferably 5/1 to 1/1.

<Oxidizing agent>
The metal film polishing liquid preferably further includes at least one oxidizing agent (metal oxidizing agent). By further containing an oxidizing agent, the polishing rate of the metal layer can be further improved. There is no restriction | limiting in particular in the said oxidizing agent, It can select suitably from the oxidizing agent used normally. Specific examples include hydrogen peroxide, peroxosulfate, nitric acid, potassium periodate, hypochlorous acid, ozone water, etc. Among these, hydrogen peroxide is preferable. These oxidizing agents can be used individually by 1 type or in mixture of 2 or more types.

  When the polishing liquid contains an oxidizing agent, the content of the oxidizing agent is preferably 0.01% by mass to 5% by mass with respect to the total mass of the polishing liquid. The content is more preferably 0.02% by mass or more, and still more preferably 0.05% by mass or more from the viewpoint of preventing metal oxidation from becoming insufficient and reducing the polishing rate. Moreover, 5 mass% or less is more preferable, and 3 mass% or less is still more preferable at the point which can produce roughness on a to-be-polished surface and can suppress dishing small. Note that an oxidizing agent that is generally available as an aqueous solution, such as aqueous hydrogen peroxide, can be prepared so that the content of the oxidizing agent contained in the aqueous solution falls within the above range in the polishing liquid.

<Organic solvent>
The polishing liquid may further contain an organic solvent. By adding the organic solvent, the wettability of layers other than the barrier layer provided in the vicinity of the barrier layer can be improved, and the polishing rate can be further improved. Although there is no restriction | limiting in particular as said organic solvent, A water-soluble thing is preferable. Here, water-soluble is defined as one that dissolves at least 0.1 g at 25 ° C. with respect to 100 g of water.

  Examples of the organic solvent include carbonate solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactone solvents such as butyl lactone and propyl lactone; ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, Glycol solvents such as ethylene glycol and tripropylene glycol; ether solvents such as tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate; methanol, ethanol, propanol, n- Butanol, n-pentanol, -Alcohol solvents such as hexanol, isopropanol and 3-methoxy-3-methyl-1-butanol; ketone solvents such as acetone and methyl ethyl ketone; other organic solvents such as dimethylformamide, N-methylpyrrolidone, ethyl acetate, ethyl lactate and sulfolane Etc.

  The organic solvent may be a glycol solvent derivative. Ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monoethyl ether, di Propylene glycol monoethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monopropyl ether, diethylene glycol monopropyl ether, triethylene glycol monopropyl ether, triplicate Glycol monoether solvents such as pyrene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether; ethylene glycol dimethyl ether, propylene glycol Dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ethyl ether, tripropylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, diethylene glycol diethyl ether , Dipropylene glycol diethyl ether, triethylene glycol diethyl ether, tripropylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol dipropyl ether, diethylene glycol dipropyl ether, dipropylene glycol dipropyl ether, triethylene glycol dipropyl ether, Examples thereof include glycol ether solvents such as tripropylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, triethylene glycol dibutyl ether, and tripropylene glycol dibutyl ether.

  Among these, at least one selected from a glycol solvent, a derivative of a glycol solvent, an alcohol solvent, and a carbonate ester solvent is preferable, and at least one selected from an alcohol solvent is more preferable. These organic solvents can be used individually by 1 type or in mixture of 2 or more types.

  When the polishing liquid contains an organic solvent, the content of the organic solvent is preferably 0.1% by mass to 95% by mass with respect to the total mass of the polishing liquid. The content of the organic solvent is more preferably 0.2% by mass or more, and still more preferably 0.5% by mass or more in terms of preventing the wettability of the polishing liquid to the substrate from being lowered. Further, the content is more preferably 50% by mass or less, and further preferably 10% by mass or less, in terms of facilitating preparation, use, waste liquid treatment, and the like of the polishing liquid.

<Surfactant>
The metal film polishing liquid according to this embodiment may further contain a surfactant. Examples of the surfactant include water-soluble anionic surfactants such as ammonium lauryl sulfate, polyoxyethylene lauryl ether ammonium sulfate, alkyl phosphate ester salt, and polyoxyethylene alkyl ether phosphate; polyoxyethylene lauryl ether, polyethylene glycol mono Examples thereof include water-soluble nonionic surfactants such as stearate. Among these, as the surfactant, a water-soluble anionic surfactant is preferable. In particular, it is more preferable to use at least one water-soluble anionic surfactant such as a polymer dispersant obtained using an ammonium salt as a copolymerization component. A water-soluble nonionic surfactant, a water-soluble anionic surfactant, a water-soluble cationic surfactant and the like may be used in combination. The content of the surfactant is, for example, 0.0001 to 0.1% by mass based on the total mass of the polishing liquid.

<Water of aqueous solvent>
The metal film polishing liquid according to this embodiment contains water. The content of water in the polishing liquid may be the remainder of the polishing liquid excluding the content of other components. Although it does not restrict | limit especially as water, Deionized water, ion-exchange water, ultrapure water, etc. are preferable.

<PH of polishing liquid>
The pH of the metal film polishing liquid according to this embodiment is preferably 2.0 or more, and more preferably 2.5 or more, from the viewpoint of suppressing corrosion of the wiring metal. When the pH is less than 2.0, hydrogen ions in the polishing liquid act on the metal wiring and promote corrosion of the metal wiring. On the other hand, the pH is preferably 3.5 or less, more preferably 3.0 or less, from the viewpoint that the barrier layer and the silicon oxide film can be removed at a good polishing rate. The reason for this effect is that when the pH exceeds 3.5, the zeta potential of the abrasive particles becomes small, which tends to repel the barrier layer and the silicon oxide film, and the polishing rate of these films decreases. It is done. In addition, in order to adjust pH, well-known pH adjusters (for example, ammonia water, potassium hydroxide, nitric acid, a sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, and an acetic acid) can be used in order to adjust pH. The pH is defined as the pH at a liquid temperature of 25 ° C.

  The pH of the polishing liquid can be measured with a pH meter (for example, model number: PHL-40, manufactured by Electrochemical Instrument Co., Ltd.). For example, after two-point calibration using a standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C.); neutral phosphate pH buffer, pH: 6.86 (25 ° C.)) The pH of the polishing liquid can be measured by putting the electrode in the polishing liquid and measuring the value after 2 minutes or more have passed and stabilized at 25 ° C.

  The constituents of the polishing liquid according to this embodiment can be stored, transported and used in a plurality of liquids. Therefore, for example, the polishing liquid according to the present embodiment may be obtained by mixing a component containing an oxidizing agent that has been stored separately and a component other than the oxidizing agent, and the first stored separately. And a second liquid (that is, a first liquid containing the abrasive particles, the methacrylic acid polymer having a weight average molecular weight of 20,000 or more, the acid, a salt thereof, and the metal corrosion inhibitor). And a second liquid containing the oxidizing agent). The first liquid may further contain an organic solvent, a surfactant and the like.

  The metal film polishing liquid of this embodiment can be suitably used for polishing a film to be polished having a wiring forming portion having a wiring density of 50% or more. Here, the wiring density is a value calculated from the respective widths of the interlayer insulating film portion and the metal wiring portion (including the barrier metal) at the portion where the wiring is formed. For example, the line and space is 100 μm / 100 μm. In this case, the wiring density in that portion is 50%.

  When the wiring density is 50% or more, the area occupied by the metal wiring portion becomes large, and thus the problem of erosion between wirings in the portion tends to become remarkable. However, polishing is performed using the polishing liquid of this embodiment. Thus, these problems can be reduced. The polishing liquid of this embodiment can also be suitably used for polishing a film to be polished having a wiring forming portion having a wiring density of 80% or more.

[Polishing method]
In the polishing method of this embodiment, a residue of a conductive material is generated, and a substrate in which no residue is generated between the metal wiring and the metal wiring is polished using the metal film polishing liquid described above. The polishing method removes the residue of the conductive material and the barrier layer. That is, using a polishing liquid containing abrasive particles, a methacrylic acid polymer having a weight average molecular weight of 20,000 or more, and an aqueous solvent, a residue of a conductive material is generated, and a portion between the metal wiring and the metal wiring is formed. This is a method of polishing a substrate on which no residue is generated. More specifically, the chemical mechanical polishing step of the substrate is formed on the surface of the substrate where the residue of the conductive material is generated and no residue is generated between the metal wiring and the metal wiring. While supplying the above-described polishing liquid between the film to be polished and the polishing cloth on the polishing surface plate, the substrate surface in a state where the surface of the substrate on which the film to be polished is provided is pressed against the polishing cloth. And removing at least a part of the film to be polished by relatively moving the polishing surface plate and the polishing surface plate.

  Hereinafter, a series of steps for forming a wiring layer in a semiconductor device using the substrate polishing method of this embodiment will be described with reference to FIG. However, the use of the metal film polishing liquid of the present embodiment is not limited to the following steps. Since the metal film polishing liquid has already been described, detailed description thereof will be omitted.

  As shown in FIG. 2 (a), the substrate before polishing the barrier layer is an insulating interlayer insulating film 1 having a predetermined pattern of recesses on the silicon substrate, and the surface of the insulating interlayer insulating film 1 on the surface. A barrier (metal) layer 2 covering the interlayer insulating film 1 is provided along the unevenness, and a conductive material layer 4 is formed on the barrier (metal) layer 2 in the recess of a predetermined pattern. In this embodiment, the “base” refers to a substrate in which predetermined layers are sequentially formed on a silicon substrate, for example.

  Examples of the insulating interlayer insulating film 1 include a silicon-based insulator and an organic polymer-based insulator. Examples of silicon-based insulators include silicon dioxide; fluorosilicate glass; organosilicate glass obtained using trimethylsilane or dimethoxydimethylsilane as a starting material; silica-based insulators such as silicon oxynitride and silsesquioxane hydride; silicon carbide A silicon nitride may be used. Examples of the organic polymer insulator include wholly aromatic low dielectric constant insulators. Among these, silicon dioxide and organosilicate glass are particularly preferable.

  The insulating interlayer insulating film 1 is formed by a CVD (chemical vapor deposition) method, a spin coat method, a dip coat method, or a spray method. Specific examples of the insulator 2 include an insulator in an LSI manufacturing process, particularly a multilayer wiring forming process.

  The barrier (metal) layer 2 is formed to prevent the conductive material from diffusing into the interlayer insulating film 1 and to improve the adhesion between the interlayer insulating film 1 and the conductive material layer 4. Examples of the barrier (metal) used in the barrier (metal) layer 2 include tantalum compounds such as tantalum, tantalum nitride, and tantalum alloys, titanium compounds such as titanium, titanium nitride, and titanium alloys, and tungsten such as tungsten, tungsten nitride, and tungsten alloys. Examples thereof include a compound, a ruthenium compound such as ruthenium, and a cobalt compound such as cobalt. The barrier (metal) layer 2 may have a single layer structure composed of one kind of these or a laminated structure composed of two or more kinds. The barrier (metal) layer 2 is formed by vapor deposition, CVD (chemical vapor deposition), ALD (atomic layer deposition), or the like.

  Examples of the conductive material used for the conductive material layer 4 include copper, copper alloys, copper oxides, copper-based metals such as copper alloys, tungsten metals such as tungsten and tungsten alloys, silver, Examples include noble metals such as gold. Among these, metals having copper as a main component such as copper, copper alloys, copper oxides, and copper alloy oxides are preferable. The conductive material layer 4 is formed by a known sputtering method, plating method or the like.

  The insulating interlayer insulating film 1 has a thickness of about 0.01 μm to 2.0 μm, the barrier (metal) layer 2 has a thickness of about 0.01 μm to 2.5 μm, and the conductive material layer 4 has a thickness of About 0.01 μm to 2.5 μm is preferable.

  The step of chemically mechanically polishing the barrier layer 2 using the metal film polishing liquid can include, for example, the following first polishing step and second polishing step. In the first polishing step of polishing the conductive material layer 4 from the state shown in FIG. 2A to the state shown in FIG. 2B, the conductive material layer 4 on the surface of the substrate before polishing is, for example, Then, polishing is performed by CMP using a polishing liquid for conductive material having a sufficiently high polishing rate ratio of conductive material layer 4 / barrier layer 2. Thereby, the board | substrate which has the conductor pattern in which the barrier layer 2 of the convex part on a board | substrate is exposed to the surface, and the electroconductive substance layer 4 was left in the recessed part is obtained. In the first polishing step, a part of the convex barrier layer 2 may be polished together with the conductive material layer 4.

  Depending on the first polishing process, a residue of the conductive material shown in FIG. 2B is generated.

  In the subsequent second polishing step, the conductor pattern obtained in the first polishing step is polished using the metal film polishing liquid of this embodiment as a film to be polished for the second polishing step.

  In the second polishing step, while the substrate is pressed onto the polishing cloth of the polishing surface plate, while supplying the metal film polishing liquid of the present embodiment between the polishing cloth and the substrate, the polishing surface plate and the substrate Are relatively moved to polish the residue of the conductive material and the barrier layer 2 exposed by the first polishing step.

  As a polishing apparatus, a general polishing apparatus having a holder for holding a substrate to be polished and a polishing platen connected to a motor or the like whose rotation speed can be changed and a polishing cloth attached thereto can be used. As an abrasive cloth, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used, and there is no restriction | limiting in particular.

The polishing conditions are not particularly limited, but the rotation speed of the polishing platen is preferably a low rotation of 200 rotations / minute (200 min ⁻¹ ) or less so that the substrate does not pop out. The pressure for pressing the substrate having the film to be polished onto the polishing cloth is preferably 1 kPa to 100 kPa, and 5 kPa to 50 kPa in order to satisfy the uniformity of the polishing speed within the surface and the flatness of the pattern. It is more preferable.

  During polishing, the metal film polishing liquid of this embodiment is continuously supplied by a pump or the like between the polishing cloth and the film to be polished. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of polishing cloth is always covered with polishing liquid. The substrate after polishing is preferably washed in running water and then dried after removing water droplets adhering to the substrate using spin drying or the like.

  In order to perform chemical mechanical polishing with the surface state of the polishing cloth always the same, it is preferable to perform a conditioning process of the polishing cloth before polishing. For example, the polishing cloth is conditioned with a liquid containing at least water using a dresser with diamond particles. Subsequently, it is preferable to perform the polishing method of the present embodiment and further add a substrate cleaning step.

  In the second polishing step, at least the exposed barrier layer 2 is polished to remove excess barrier portions. Further, the conductive material layer 4 embedded in the recess may be polished together with the barrier layer 2.

  The insulating interlayer insulating film 1 under the barrier (metal) layer 2 of the convex portion is completely exposed, the conductive material layer 4 serving as a wiring layer is left in the concave portion, and the barrier (metal) is formed at the boundary between the convex portion and the concave portion. The polishing is finished when a substrate having a desired pattern in which the cross section of the layer 2 is exposed is obtained.

  In order to ensure better flatness at the end of polishing, in addition to over polishing (for example, if the time until a desired pattern is obtained in the second polishing step is 100 seconds, in addition to this 100 second polishing, Polishing for an additional 50 seconds may be referred to as over-polishing 50%). In the case of overpolishing, a part of the insulating interlayer insulating film 1 is also removed by polishing.

  A second-layer insulator and metal wiring are further formed on the metal wiring thus formed, and then polished to obtain a smooth surface over the entire surface of the semiconductor substrate. By repeating this step a predetermined number of times, a semiconductor device having a desired number of wiring layers can be manufactured.

  The polishing liquid of the present embodiment can be used not only for polishing a metal film formed on a semiconductor substrate as described above but also for polishing a substrate such as a magnetic head.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples without departing from the technical idea of the present invention. For example, the type of polishing liquid material and the blending ratio thereof may be other than those described in this embodiment, and the composition and structure of the polishing target may be other than those described in this embodiment.

<Examples and Comparative Examples>
(Metal film polishing liquid preparation method)
Table 1 shows the molar ratio (mol%) of each monomer in the methacrylic acid polymer and the weight average molecular weight of the polymer. The monomer components shown in Table 1 were polymerized to obtain methacrylic acid polymers.

  Further, according to Tables 2 to 3, a predetermined amount of abrasive particles, methacrylic acid polymer, acid compound (aqueous solvent acid), metal anticorrosive agent, etc. are mixed to polish each metal film of each example and each comparative example. A liquid was prepared. Incidentally, colloidal silica having an average particle diameter of 70 nm was used as the abrasive particles. The pH was measured with a pH meter (manufactured by Electrochemical Instrument Co., Ltd., model number: PHL-40).

(Polishing copper pattern substrate)
A copper film other than the groove of the pattern substrate with copper wiring (ATDF (Advanced Technology Development Facility) 854 CMP pattern: 500 nm thick interlayer insulating film made of silicon dioxide) is used as a polishing liquid for copper film polishing (manufactured by Hitachi Chemical Co., Ltd., HS-H635) is polished by a known CMP method so that the convex barrier layer is exposed on the surface to be polished and copper residue is present on the upper portion of the barrier layer in the field portion as shown in FIG. A substrate in such a state was obtained. This board | substrate was used for the grinding | polishing characteristic evaluation of the polishing liquid of each Example and a comparative example. The barrier layer of the pattern substrate was made of a tantalum nitride film having a thickness of 250 mm.

  The pattern substrate was subjected to chemical mechanical polishing for 50 seconds under the following polishing conditions with each metal film polishing liquid prepared by the polishing liquid preparation method. This corresponds to the second polishing step, and the convex interlayer insulating film was exposed to the surface to be polished in about 20 seconds, and the exposed interlayer insulating film was polished in the convex portion for the remaining 30 seconds.

[Substrate polishing conditions]
Polishing device: Single-sided metal film polishing machine (MIRRA, Applied Materials)
Abrasive cloth: Abrasive cloth made of suede polyurethane resin (Fujibo Holdings Co., Ltd.)
Surface plate rotation speed: 93 rotations / min (93 min ⁻¹ )
Head rotation speed: 87 rotations / min (87 min ⁻¹ )
Polishing pressure: 21 kPa
Supply amount of polishing liquid: 200 ml / min

  Next, a sponge brush (made of polyvinyl alcohol resin) was pressed against the surface to be polished of the patterned substrate polished in the substrate polishing step, and the substrate and the sponge brush were rotated while supplying distilled water to the substrate, and washed for 60 seconds. . Next, the sponge brush was removed, and distilled water was supplied to the polished surface of the substrate for 60 seconds. Finally, the substrate was rotated at high speed to blow off distilled water and dried to obtain a pattern substrate to be used in the following evaluation.

(Flatness evaluation)
The following evaluations (1) to (3) were performed on the pattern substrate obtained in the substrate cleaning step.

(1) Amount of polishing of interlayer insulating film: The film thickness of the interlayer insulating film portion is measured using a patterned substrate with copper wiring, and a metal wiring portion having a width of 100 μm and an interlayer insulating film portion having a width of 100 μm are alternately arranged. The thickness of the interlayer insulating film in the stripe-shaped pattern portion having a total width of 2900 μm was obtained by an optical film thickness meter, and was defined as the amount of interlayer insulating film polishing.

(2) Inter-wiring erosion amount: In the pattern substrate obtained in the above-described substrate cleaning process, as shown in FIG. 3A, a metal wiring portion having a width of 70 μm and an interlayer insulating film portion having a width of 30 μm are alternately arranged. The surface shape of the stripe-shaped pattern portion having a total width of 2990 μm was measured with a stylus type step meter. Next, as shown in FIG. 2B, the difference between the maximum polishing amount (B) of the interlayer insulating film in the stripe pattern portion and (A) of the interlayer insulating film portion on the outer edge of the stripe pattern portion ( B)-(A), that is, the amount of erosion between wirings was obtained and used as an index of flatness.
(3) Dishing amount: In the patterned substrate obtained in the above substrate cleaning process, as shown in FIG. 3A, the total width in which metal wiring portions having a width of 70 μm and interlayer insulating film portions having a width of 30 μm are alternately arranged. The surface shape of the 2990 μm stripe pattern portion was measured with a stylus type step gauge. Next, as shown in FIG. 2B, the difference between the maximum polishing amount (C) of the metal wiring layer of the stripe pattern portion and (A) of the interlayer insulating film portion at the outer edge of the stripe pattern portion ( C)-(A), that is, the dishing amount was obtained and used as an index of flatness.

  FIG. 3 is a schematic cross-sectional view of a stripe pattern portion in which a metal wiring portion having a width of 70 μm and an interlayer insulating film portion having a width of 30 μm are alternately arranged on the patterned substrate with copper wiring, and 11 is an interlayer insulating film, 13 is a barrier layer, 15 is a metal wiring layer, A is the polishing amount of the interlayer insulating film portion at the outer edge of the stripe pattern portion, B is the maximum polishing amount of the interlayer insulating film portion of the stripe pattern portion, and C is the stripe pattern The maximum value of the polishing amount of the metal wiring layer of the part is shown.

  The above evaluation results are shown in Tables 2 and 3.

(Evaluation of polishing rate)
The following substrates (a) to (e) were used for evaluation of the polishing rate of the blanket substrate.
Blanket substrate (a): A silicon substrate on which copper (thickness: 1000 nm) is formed by a plating method.
Blanket substrate (b): A silicon substrate on which tantalum nitride (thickness: 200 nm) is formed by sputtering.
Blanket substrate (c): A silicon substrate on which silicon dioxide (thickness: 1000 nm) is formed by CVD.
Blanket substrate (d): A silicon substrate on which an organosilicate glass (thickness: 1000 nm) is formed.
Using the blanket substrates (a) to (d), chemical mechanical polishing was performed for 60 seconds under the substrate polishing conditions with the polishing liquids of Examples 1 to 6.

[Calculation of polishing speed]
The polishing rate was calculated by the following method using the blanket substrates (a) to (d).
Copper film, tantalum nitride film: About blanket substrates (a) and (b), film thickness before and after polishing using a metal film thickness measuring device (product name “VR-120 / 08S” manufactured by Hitachi Kokusai Electric Co., Ltd.) The difference was measured, and from the obtained results, the polishing rate when polishing the copper film (Cu polishing rate) [Å / min] and the polishing rate when polishing the tantalum nitride film (TaN polishing rate) [Å / min] Evaluated.
Silicon dioxide film, organosilicate glass film: obtained by measuring the film thickness difference before and after polishing using a film thickness measuring device (manufactured by Dainippon Screen Mfg. Co., Ltd., product name “Lambda Ace, VL-M8000LS”) From the results, the polishing rate when polishing the silicon dioxide film (SiO ₂ polishing rate) [Å / min] and the polishing rate when polishing the organosilicate glass film (SiOC polishing rate) [Å / min] were evaluated.
These results are shown in Table 4.

  As is apparent from Table 2, in Examples 1 to 6, by including a methacrylic acid polymer having a specific weight average molecular weight, erosion between wirings is effectively suppressed, and high flatness of the surface to be polished is obtained. .

On the other hand, in Comparative Examples 1 to 5 in Table 3, erosion between wirings was larger than that in Examples, and the flatness of the polished surface was low.
In Comparative Example 6, erosion between the wirings was small, but dishing occurred greatly, and the flatness of the surface to be polished was low.

  From Table 4, it was found that in Examples 1 to 6, good polishing rates were obtained for copper, tantalum nitride, silicon dioxide, and organosilicate glass. Therefore, in the metal film polishing liquid of the present invention containing the methacrylic acid polymer, erosion and dishing between wirings can be effectively performed by using the methacrylic acid polymer having a weight average molecular weight of 20,000 or more. It is suggested that it is suppressed. That is, from the above results, it is suggested that the metal film polishing liquid of the present invention can be effectively polished while suppressing erosion and dishing between wirings.

DESCRIPTION OF SYMBOLS 1 ... Interlayer insulating film 2 ... Barrier (metal) layer 3 ... Metal wiring layer 4 ... Conductive material layer 11 ... Interlayer insulating film 13 ... Barrier (metal) layer 15 ... Metal wiring layer

Claims (11)

  A polishing solution for metal films, comprising abrasive particles, a methacrylic acid polymer having a weight average molecular weight of 20,000 or more, and an aqueous solvent.   The metal film polishing liquid according to claim 1, wherein the aqueous solvent is water or water and an acid.   The metal film polishing liquid is a polishing liquid for chemically mechanically polishing a substrate in which a residue of a conductive material is generated in the periphery of the metal wiring and no residue is generated between the metal wiring and the metal wiring. The polishing liquid for metal films according to claim 1 or 2.   The methacrylic acid polymer is at least one selected from the group consisting of a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid. The polishing liquid for metal films according to one item.   5. The metal film according to claim 1, wherein the abrasive particles contain at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. Polishing fluid.   Furthermore, the polishing liquid for metal films as described in any one of Claims 1-5 containing the compound which has a triazole skeleton as a metal anticorrosive.   Furthermore, the polishing liquid for metal films as described in any one of Claims 1-6 containing an organic solvent.   Furthermore, the polishing liquid for metal films as described in any one of Claims 1-7 containing a metal oxidizing agent.   The polishing liquid for metal films according to any one of claims 1 to 8, wherein the pH of the polishing liquid for metal films is 2.0 or more and 3.5 or less.   The polishing liquid for the metal film is obtained by mixing the first liquid containing the abrasive particles, the methacrylic acid polymer, the aqueous solvent and the metal anticorrosive and the second liquid containing the oxidizing agent. The metal film polishing liquid according to claim 8 or 9. Conductivity of a substrate having an interlayer insulating film having a concave portion and a convex surface, a barrier layer covering the surface of the interlayer insulating film, and a conductive material layer filling the concave portion and covering the barrier layer A first polishing step of polishing the material layer to expose the barrier layer of the convex portion;
The barrier layer of the substrate exposed in the first polishing step is polished with the metal film polishing liquid according to claim 1 to expose the convex interlayer insulating film. A polishing method comprising two polishing steps.

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