JP6670715B2 - Polishing composition used for polishing a polishing object having a layer containing metal - Google Patents

Description

  The present invention relates to a polishing composition used for polishing a polishing object having a metal-containing layer.

  2. Description of the Related Art In recent years, electronic devices such as computers have achieved high performance such as miniaturization, multifunctionality, and high speed due to high integration brought about by miniaturization of LSI manufacturing processes. A chemical mechanical polishing (CMP) method is used in a new microfabrication technique associated with such high integration of LSI. The CMP method is a technique that is frequently used in the LSI manufacturing process, particularly in the flattening of the interlayer insulating film, the formation of metal plugs, and the formation of embedded wiring (damascene wiring) in the multilayer wiring forming process.

  The formation of metal plugs and wiring in a semiconductor device is generally performed by forming a conductor layer made of the above-described metal on an insulator layer made of silicon oxide having a concave portion, and then forming a conductor layer on the insulator layer. This is performed by removing a part by polishing until the insulator layer is exposed. The polishing process is roughly classified into a main polishing process for performing polishing for removing most of the conductor layer to be removed, and a buff polishing process for finish polishing the conductor layer and the insulator layer.

  A general method of CMP is to attach a polishing pad on a circular polishing platen (platen), soak the polishing pad surface with a polishing composition, press the surface of the substrate on which the metal film is formed, and press the surface from the back surface. The polishing platen is rotated while a predetermined pressure (polishing pressure) is applied, and the metal film (for example, tungsten) is removed by mechanical friction between the polishing composition and the metal film. Further, by the action of the chemical component contained in the polishing composition, the mechanical polishing effect due to the relative movement between the polishing composition and the object to be polished is increased, and a high-speed and smooth polished surface is obtained.

  The polishing composition used in the semiconductor device manufacturing process generally contains a polishing accelerator such as an acid, an oxidizing agent, and abrasive grains. On the other hand, in Patent Document 1, a peroxy oxidant-free CMP polishing slurry composition is reported, assuming that the use of a peroxy oxidant causes a recess (a phenomenon of excessively polishing tungsten) of a tungsten plug. ing.

JP 2013-42131 A

However, it has been confirmed that when the polishing composition of Patent Document 1 is used in a process for forming a tungsten plug or a tungsten wiring, particularly in a buff polishing step in the process, the polished surface of tungsten is roughened.

  In the composition of Patent Document 1, the surface after polishing becomes rough, and sufficient planarization cannot be achieved.

  Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polishing composition used for polishing an object to be polished having a layer containing a metal that can achieve sufficient planarization.

  Another object of the present invention is to provide a polishing composition used for polishing an object to be polished having a metal-containing layer capable of ensuring a low etching rate and a high polishing rate in a well-balanced manner.

  The present inventors have intensively studied to solve the above problems. As a result, they have found that the above problem can be solved by using an anticorrosive having an acidic functional group and a basic functional group in the composition, and completed the present invention.

  That is, the above-mentioned objects are a polishing composition used for polishing a polishing object having a layer containing a metal, which comprises an abrasive, an oxidizing agent, a dispersion medium, an acidic functional group and a basic functional group. It can be achieved by a polishing composition containing an anticorrosive.

  By using the polishing composition of the present invention, a polishing target having a metal-containing layer can be polished smoothly. Further, by using the polishing composition of the present invention, an object to be polished having a layer containing a metal can be polished at a high polishing rate while keeping the etching rate low.

  The polishing composition used for polishing an object to be polished having a layer containing a metal of the present invention includes an abrasive, an oxidizing agent, a dispersion medium, and an anticorrosive having an acidic functional group and a basic functional group. It is a polishing composition. According to the polishing composition having the above configuration, a polishing target having a metal-containing layer can be polished smoothly. Further, according to the polishing composition of the present invention, an object to be polished having a metal-containing layer as an object to be polished can be polished at a high polishing rate while keeping the etching rate low.

  In this specification, the “polishing composition used for polishing an object to be polished having a layer containing a metal” is also simply referred to as a “polishing composition according to the present invention” or a “polishing composition”. The “object to be polished having a layer containing metal” is also simply referred to as “object to be polished metal”.

The composition of Patent Document 1 contains a diquaternary compound of the formula (I) consisting of a divalent cation moiety and a divalent anion moiety (particularly a quaternary amine compound; paragraph “0029”). The presence of this diquaternary compound can certainly keep the etching rate low. However, the cation portion of the diquaternary compound is adsorbed on the surface of the abrasive grains (for example, Si ⁻ ) and induces aggregation and sedimentation of the abrasive grains, so that the stability of the abrasive grains is reduced. At the same time, since the secondary particle diameter of the abrasive grains becomes large, the surface after polishing becomes rough (the value of the surface roughness RMS becomes high). Since the beginning of the CMP process, tungsten has been applied because of its high electrical conductivity and high burying properties. However, it is widely known that tungsten is difficult to process because of its high hardness and brittleness, and that the final finished surface roughness is lower than metals such as copper and aluminum. In addition to the above, surface roughness of tungsten crystal grains has become an important problem due to recent miniaturization (high integration), and this surface roughness is referred to as chemical mechanical polishing (hereinafter simply referred to as “CMP”). It is required to solve this problem. For this reason, the composition disclosed in Patent Document 1 cannot sufficiently achieve the flatness currently required. In the composition of Patent Document 1, potassium iodate is used essentially as an oxidizing agent, and this oxidizing agent promotes formation of a metal oxide film (for example, a tungsten oxide (WO ₃ ) film). However, this potassium iodate causes the generation of iodine gas. When inhaled by humans, iodine gas may cause coughing, wheezing, breathlessness, etc.When manufacturing the composition or polishing using the composition, provide sufficient ventilation or allow workers to wear protective gloves or protective clothing. It is necessary to strictly control the working environment, such as the need to wear garments, and in view of the soundness of the working environment in recent years, it is desirable not to use compounds containing iodine as much as possible.

On the other hand, the present invention is characterized by using an anticorrosive having an acidic functional group and a basic functional group in the composition. According to this configuration, an object to be polished having a layer containing a metal can be polished smoothly (to a low surface roughness (RMS)) without using the diquaternary compound. Further, by using the polishing composition of the present invention, an object to be polished having a layer containing a metal can be polished at a high polishing rate while keeping the etching rate low. Although the detailed mechanism for achieving the above effects is unknown, it is considered as follows. The following mechanism is speculative and does not limit the technical scope of the present invention. That is, as described above, conventionally, since metal films such as tungsten are hardly etched, emphasis has been placed on polishing an object to be polished having a layer containing metal at a high polishing rate. However, in recent years, a technique capable of thinning a layer containing a metal (a polishing object having a layer containing a metal) has been developed. Therefore, the improvement of the polishing rate is not so important. As a result, emphasis has been placed on planarization of the surface. Usually, chemical mechanical polishing (CMP) of a metal-containing layer is performed by the following mechanism: the surface of the metal-containing layer is oxidized by an oxidizing agent contained in the polishing composition, and the metal surface is formed on the substrate surface. An oxide film is formed. The metal oxide film is polished by being physically scraped by the abrasive grains, and the polished metal surface is also oxidized by an oxidizing agent to form a metal oxide film, and the metal oxide film is scraped by the abrasive grains Is repeated. However, the conventional method has a problem that the substrate surface after polishing does not have sufficient smoothness. The inventors of the present invention have conducted intensive studies on the above problems, and have presumed that corrosion of grain boundaries between crystal grains is a cause of a decrease in surface roughness. That is, when a metal oxide (for example, tungsten oxide) comes into contact with water and is dissolved as a metal hydroxide (for example, tungsten hydroxide), dissolution by this chemical reaction is faster than scraping by abrasive grains. It was presumed that the etching rate was increased and the surface was roughened. Here, increasing the scraping speed by the abrasive grains was also considered as one of the solutions, but it was necessary to increase the abrasive grain concentration, and it was considered that the practicality was low due to the high cost. Therefore, the present inventors have conducted intensive studies on the above-mentioned dissolution, that is, other means for suppressing the etching rate, and found that an anticorrosive having an acidic functional group and a basic functional group was used in the polishing composition. Thought it was effective. Specifically, an anticorrosive having an acidic functional group (anionic functional group) and a basic functional group (cationic functional group) is adsorbed on the surface of a metal oxide (for example, tungsten oxide) to cover the metal oxide. An etching suppressing film is formed on the surface to suppress dissolution of the metal oxide. When a polishing composition containing such an anticorrosive is used, dissolution (elution) of a metal (for example, tungsten) from a substrate during polishing can be suppressed, and the surface roughness after polishing can be reduced. Further, when a cationic anticorrosive of a diquaternary compound as in Patent Document 1 is used, since the zeta potential of the surface of the abrasive (for example, Si ⁻ ) is negatively charged, the anticorrosive is an abrasive. When a large amount of an anticorrosive is used in order to easily adsorb to the surface of the steel and to obtain a good anticorrosive effect, the abrasive particles are aggregated and further settled. If the amount of the anticorrosive used is reduced in order to avoid agglomeration of the abrasive grains, a favorable effect of suppressing the etching rate cannot be obtained. However, the anticorrosive agent according to the present invention has a cationic basic functional group and an anionic acidic functional group. At the same time when the cationic functional group is adsorbed on the metal oxide, the anionic functional group is also self-organized. Can be formed on the surface of the metal oxide without causing agglomeration of the abrasive grains with a relatively small amount of the anticorrosive agent, and the etching rate can be suppressed. .

  Therefore, according to the polishing composition of the present invention, a layer containing a metal (object to be polished) can be polished at a high polishing rate while keeping the etching rate low. In addition, since the elution of metal can be suppressed, polishing a metal-containing layer (object to be polished) with the polishing composition of the present invention can reduce the surface roughness (RMS) and provide a layer (substrate) having a flat surface. Can be obtained. In addition, according to the polishing composition of the present invention, a metal-containing layer (object to be polished) can be polished on a smooth surface at a high polishing rate without increasing the concentration of abrasive grains, while keeping the etching rate low.

  Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to only the following embodiments.

  In this specification, unless otherwise specified, the operation and measurement of physical properties are performed under the conditions of room temperature (20 to 25 ° C.) / Relative humidity of 40 to 50% RH.

[Object to be polished]
The object to be polished according to the present invention is a layer containing a metal. Here, the layer containing metal only needs to have at least a surface to be polished containing metal. For this reason, a layer containing a metal is a substrate made of a metal, a layer containing a metal, or a substrate having a layer made of a metal (for example, a layer containing a metal or a metal on a polymer or other metal substrate). (A substrate on which constituent layers are arranged). Preferably, the layer containing a metal is a layer made of a metal (for example, a substrate) or an object to be polished having a layer made of a metal (for example, a substrate).

  Here, the metal is not particularly limited. Examples include tungsten, copper, aluminum, cobalt, hafnium, nickel, titanium, tantalum, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, osmium and the like. The metal may be included in the form of an alloy or a metal compound. These metals may be used alone or in combination of two or more. The polishing composition of the present invention can be suitably used for a high integration technique brought about by miniaturization of an LSI manufacturing process, and is particularly suitable for polishing a material for a plug or a via hole around a transistor. As a material to be filled, tungsten, copper, aluminum, and cobalt are preferable, and tungsten is more preferable. That is, according to a preferred embodiment of the present invention, the metal is tungsten (the polishing composition of the present invention is used for polishing an object to be polished having a layer containing tungsten).

[Polishing composition]
The polishing composition of the present invention contains abrasive grains, an oxidizing agent, a dispersion medium, and an anticorrosive having an acidic functional group and a basic functional group. Hereinafter, the configuration of the polishing composition of the present invention will be described.

(Abrasive)
The polishing composition of the present invention essentially contains abrasive grains. The abrasive grains contained in the polishing composition have an action of mechanically polishing the object to be polished, and improve the polishing rate of the object to be polished by the polishing composition.

  The abrasive used may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include, for example, particles made of a metal oxide such as silica, alumina, ceria, and titania, silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include, for example, polymethyl methacrylate (PMMA) particles. The abrasive grains may be used alone or in combination of two or more. Further, as the abrasive grains, a commercially available product or a synthetic product may be used.

  Among these abrasive grains, silica is preferred, and colloidal silica is particularly preferred.

  The abrasive grains may be surface-modified. Since ordinary colloidal silica has a zeta potential value close to zero under acidic conditions, the silica particles do not repel each other under acidic conditions and tend to aggregate. On the other hand, abrasive grains surface-modified so that the zeta potential has a relatively large negative value even under acidic conditions, repel each other strongly even under acidic conditions, and are well dispersed. As a result, the storage stability of the polishing composition can be improved. Such a surface-modified abrasive can be obtained, for example, by mixing a metal such as aluminum, titanium or zirconium or an oxide thereof with the abrasive and doping the surface of the abrasive.

  Among them, colloidal silica on which an organic acid is immobilized is particularly preferred. The fixation of the organic acid to the surface of the colloidal silica contained in the polishing composition is performed, for example, by chemically bonding a functional group of the organic acid to the surface of the colloidal silica. Simply coexisting colloidal silica and an organic acid does not fix the organic acid to the colloidal silica. When sulfonic acid, which is a kind of organic acid, is immobilized on colloidal silica, for example, “Sulfonic acid-functionized silica through quantitative oxidation of thiol groups”, Chem. Commun. 246-247 (2003). Specifically, a silane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxysilane is coupled to colloidal silica, and then the thiol group is oxidized with hydrogen peroxide, whereby the sulfonic acid is immobilized on the surface. The obtained colloidal silica can be obtained. Alternatively, if the carboxylic acid is immobilized on colloidal silica, for example, “Novel Silane Coupling Agents Containing a Photolabile 2-Nitrobenzyl Ester for Introduction of a Container Carousel Group, for example. 229 (2000). Specifically, by coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to colloidal silica and then irradiating light, colloidal silica having a carboxylic acid immobilized on the surface can be obtained. .

  The average degree of association of the abrasive grains is also preferably less than 5.0, more preferably 3.0 or less, and even more preferably 2.5 or less. Within such a range as the average degree of association of the abrasive grains decreases, the surface roughness due to the shape of the abrasive grains can be improved. The average degree of association of the abrasive grains is also preferably 1.0 or more, more preferably 1.05 or more. The average degree of association is obtained by dividing the value of the average secondary particle size of the abrasive grains by the value of the average primary particle size. As the average degree of association of the abrasive grains increases, the polishing rate of the object to be polished by the polishing composition is advantageously improved.

  The lower limit of the average primary particle diameter of the abrasive grains is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more. Further, the upper limit of the average primary particle diameter of the abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. In such a range, the polishing rate of the object to be polished by the polishing composition is improved, and the occurrence of surface defects on the surface of the object to be polished after polishing with the polishing composition is further suppressed. be able to. The average primary particle size of the abrasive grains is calculated based on, for example, the specific surface area of the abrasive grains measured by the BET method.

  The lower limit of the average secondary particle diameter of the abrasive grains is preferably at least 15 nm, more preferably at least 20 nm, and even more preferably at least 30 nm. In addition, the upper limit of the average secondary particle diameter of the abrasive grains is preferably 300 nm or less, more preferably 260 nm or less, and even more preferably 220 nm or less. In such a range, the polishing rate of the object to be polished by the polishing composition is improved, and the occurrence of surface defects on the surface of the object to be polished after polishing with the polishing composition is further suppressed. be able to. The secondary particles referred to herein are particles formed by associating abrasive grains in the polishing composition, and the average secondary particle diameter of the secondary particles is measured by, for example, a dynamic light scattering method. be able to.

  The upper limit of the aspect ratio of the abrasive grains in the polishing composition is less than 2.0, preferably 1.8 or less, more preferably 1.5 or less. Within such a range, the surface roughness due to the shape of the abrasive grains can be improved. The aspect ratio is a value obtained by taking the smallest rectangle circumscribing the image of the abrasive grains using a scanning electron microscope and dividing the length of the long side of the rectangle by the length of the short side of the same rectangle. And can be determined using general image analysis software. The lower limit of the aspect ratio of the abrasive grains in the polishing composition is 1.0 or more. The closer to this value, the better the surface roughness due to the shape of the abrasive grains.

  Particle diameter (D90) of the abrasive particles in the polishing composition when the integrated particle weight reaches 90% of the total particle weight from the fine particle side in the particle size distribution determined by the laser diffraction scattering method, and the total particle weight of all the particles The lower limit of D90 / D10, which is the ratio to the particle diameter (D10) when reaching 10% of the particle diameter, is 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more. More preferred. Also, in the abrasive grains in the polishing composition, the diameter (D90) of the particles when the integrated particle weight reaches 90% of the total particle weight from the fine particle side in the particle size distribution obtained by the laser diffraction scattering method, and the total number of particles. The upper limit of the ratio D90 / D10 to the particle diameter (D10) when reaching 10% of the particle weight is not particularly limited, but is preferably 2.04 or less. Within such a range, the surface roughness due to the shape of the abrasive grains can be improved.

  The lower limit of the content of the abrasive grains in the polishing composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and most preferably 1% by mass or more. . Further, the upper limit of the content of the abrasive grains in the polishing composition is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. Within such a range, the polishing rate of the object to be polished is improved, and the cost of the polishing composition can be suppressed, and the surface of the object to be polished after polishing using the polishing composition The occurrence of defects can be further suppressed.

(Anticorrosive)
The polishing composition of the present invention essentially contains an anticorrosive having an acidic functional group and a basic functional group. Due to the presence of the anticorrosive agent according to the present invention, the dissolution (elution) of the metal to be polished is suppressed, and the metal-containing layer (object to be polished) can be polished smoothly (with a low surface roughness (RMS)). Further, it is possible to polish a layer containing metal (polishing target) at a high polishing rate while keeping the etching rate low.

  Examples of the acidic functional group of the anticorrosive according to the present invention include a carboxyl group, an acid anhydride group, a sulfo group, a thiol group, a phosphoric acid group, an acidic phosphoric ester group, a phosphonic acid group, and the like. It is preferable that the acidic functional group of the anticorrosive is a carboxyl group, a phosphate group, and a salt thereof, and an acidic phosphate group and a salt thereof, from the viewpoint of the film formation speed and the film strength on the metal surface. The acidic phosphate group is a group in which some of the phosphorus-bonded hydroxyl groups have been alkoxylated. Examples of the alkoxy group include a lower alkoxy group such as a methoxy group, an ethoxy group, and a propoxy group. The lower alkoxy group preferably has 1 to 8 carbon atoms.

  Examples of the basic functional group of the anticorrosive according to the present invention include an amino group, an imino group, an ammonium base, and a heterocyclic group having a basic nitrogen atom. From the viewpoint of dispersion stability of the composition, the basic functional group of the anticorrosive is preferably an amino group or an ammonium group. The amino group may be a substituted or unsubstituted primary amino group, secondary amino group or tertiary amino group. The ammonium base may be a tertiary ammonium base or a quaternary ammonium base.

  The acid value of the anticorrosive according to the present invention is preferably from 5 to 300 mgKOH / g, more preferably from 5 to 150 mgKOH / g. The amine value of the anticorrosive according to the present invention is preferably from 5 to 300 mgKOH / g, more preferably from 5 to 150 mgKOH / g. That is, according to a preferred embodiment of the present invention, the anticorrosive has an acid value of 5 to 150 mgKOH / g and an amine value of 5 to 150 mgKOH / g. When the acid value and the amine value are within the above ranges, the anticorrosive agent can effectively form an anticorrosion coating on the surface of the object to be polished without causing agglomeration of abrasive grains.

  In addition, in this specification, "acid value" represents the acid value per 1 g of the anticorrosive according to the present invention, and can be determined by a potentiometric titration method according to JIS-K-0070. "Amine value" refers to the amine value per 1 g of the solid content of the anticorrosive according to the present invention, which is determined by a potentiometric titration method using a 0.1N aqueous hydrochloric acid solution, and then converted to an equivalent of potassium hydroxide. Say.

  The acidic functional groups are self-adsorbed to the surface of the metal oxide to be polished, and the basic functional groups are adsorbed to the surface of the metal oxide to be polished having a negative zeta potential. As a result, the anticorrosive forms a film on the surface of the metal oxide. The coating made of the anticorrosive suppresses the dissolution (elution) of the metal, reduces the etching rate, and allows the object to be polished to be polished smoothly.

  The anticorrosive having an acidic functional group and a basic functional group of the present invention is preferably a polymeric anticorrosive. When a polymeric anticorrosive is used, the weight average molecular weight of the anticorrosive is usually 1,000 or more. The weight average molecular weight is preferably from 1,000 to 100,000, and more preferably from 1,000 to 10,000. If the weight average molecular weight of the anticorrosive is 1,000 or more, the acidic or basic functional groups of the anticorrosive are adsorbed on the surface of the object to be polished, and effectively form an anticorrosive coating together with the polymer chain portion of the anticorrosive. it can. On the other hand, if the weight average molecular weight of the anticorrosive is 100,000 or less, it prevents aggregation with abrasive grains. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using polystyrene as a standard substance. When using a polymeric anticorrosive as an anticorrosive, the bonding position of the acidic functional group and the basic functional group to the polymer is not particularly limited, may be a main chain, may be a side chain, It may be both a main chain and a side chain.

  In one embodiment of the present invention, the anticorrosive having an acidic functional group and a basic functional group is a compound represented by the following formula (1):

In the formula (1), R ¹ and R ² are each independently a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 8 to 16 carbon atoms. Specific examples include a substituted or unsubstituted octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group and the like.More specifically, for example, n- Octyl, n-decyl, n-undecyl, lauryl (n-dodecyl), n-tridecyl, n-tetradecyl, n-pentadecyl, isotridecyl, s-tridecyl and t-tridecyl groups No. Among these, from the viewpoint of suppressing the etching rate, a substituted or unsubstituted linear or branched alkyl group having 12 to 15 carbon atoms is preferable. More preferably, it is a substituted or unsubstituted linear or branched alkyl group having 13 carbon atoms (n-tridecyl group, isotridecyl group, s-tridecyl group, t-tridecyl group).

Y ¹ and Y ² are each independently a single bond or a group represented by the following formula (i), and at least one of Y ¹ and Y ² is a group represented by the following formula (i);

In the formula (i), R ³ is an alkylene group having 2 to 6 carbon atoms. Specific examples include an ethylene group, n- propylene, i- propylene, n- butylene, i- butylene, n- pentylene, n- hexylene and the like, there are a plurality of ^{R 3} are the same Or different. Among them, R ³ is preferably an ethylene group from the viewpoint of more effectively exhibiting the effects of the present invention.

  n is an integer of 2 to 200, and from the viewpoint of suppressing the etching rate, n is preferably an integer of 4 to 200, and more preferably an integer of 4 to 130.

* Represents a position bonding to R ¹ or R ² in the formula (1).

X ⁺ is an ammonium ion, a primary ammonium ion, a secondary ammonium ion, a tertiary ammonium ion, or a quaternary ammonium ion. Specific examples include ammonium ion, methylammonium ion, dimethylammonium ion, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, and tetrapentylammonium ion. Of these, X ⁺ represents an ammonium ion (NH ₄ ⁺ ).

  Specifically, examples of the compound used as the anticorrosive of the present invention include ammonium alkyl ether phosphate having a polyoxyethylene structure. More specifically, for example, ammonium polyoxyethylene isotridecyl ether phosphate (additional mole number of ethylene oxide = 130), polyoxyethylene isotridecyl ether ammonium phosphate (additional mole number of ethylene oxide = 70), polyoxyethylene Ammonium dodecyl ether phosphate (additional mole number of ethylene oxide = 20), dipolyoxyethylene (C12-15) alkyl ether ammonium phosphate (additional mole number of ethylene oxide = 2), polyoxyethylene (C12-15) alkyl ether phosphorus Ammonium (additional moles of ethylene oxide = 2), sodium dipolyoxyethylene lauryl ether phosphate (additional moles of ethylene oxide = 10), dipolyoxyethylene (C12-15) alkylate Ammonium phosphate (additional mole number of ethylene oxide = 4), dipolyoxyethylene (C12-15) alkyl ether phosphate ammonium (additional mole number of ethylene oxide = 6), dipolyoxyethylene (C12-15) alkyl ether phosphate Ammonium (addition mole number of ethylene oxide = 10), ammonium polyoxyethylene lauryl ether phosphate (addition mole number of ethylene oxide = 10), ammonium polyoxyethylene (C12-15) alkyl ether phosphate (addition mole number of ethylene oxide = 4) ) And the like. "C12-15" in the above compound names means those having 12 to 15 carbon atoms in the alkyl group and mixtures thereof.

  The anticorrosive according to the present invention may be used alone or in combination of two or more.

  As the anticorrosive according to the present invention, a synthetic product may be used, or a commercially available product may be used.

  When a polymer anticorrosive is used as the anticorrosive having an acidic functional group and a basic functional group, a synthetic polymer may be used. Typical synthetic polymers that can be used are vinyl polymer polymers and polycondensation polymers. The acidic functional group and the basic functional group in the vinyl polymer-based polymer having an acidic functional group and a basic functional group are each derived from a monomer at the time of vinyl polymerization. Examples of vinyl monomers having an acidic functional group include carboxyls such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, crotonic acid, fumaric acid, monoalkyl maleate, and monoalkyl fumarate. Group-containing vinyl monomers. Examples of monomers having a basic function include N, N-dimethylaminoethyl (meth) acrylate, N-methylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl. Examples include aminoalkyl group-containing acrylates and aminoalkyl group-containing methacrylates such as (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, and N, N-dimethylaminobutyl (meth) acrylate. Examples include aminoalkyl group-containing acrylamide and aminoalkyl group-containing methacrylamide such as aminoethyl (meth) acrylamide and N, N-dimethylaminopropyl (meth) acrylamide. The term “(meth) acryl” means “acryl or methacryl”. The acidic functional group-containing vinyl monomer and the basic functional group-containing vinyl monomer are each polymerized and then block-polymerized, or only one of them is polymerized, and then the other is graft-polymerized. Good. Polycondensation polymers include polyurethane, polyester, polyoxyalkylene, polyoxyalkylene / polyester copolymer, polyamide, phenolic resin, urea resin, melamine resin, polycarbonate, epoxy resin, alkyd resin, polyalkyleneimine (polyethyleneimine, etc.), Nitrogen-containing polymers such as polyvinylpyrrolidone, polyallylamine, and polyether polyamine (such as polyoxyethylene polyamine) are included.

  The lower limit of the content of the anticorrosive in the polishing composition is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, and 0.005% by mass or more. Is more preferred. Further, the upper limit of the content of the anticorrosive in the polishing composition is preferably 1% by mass or less, more preferably 0.1% by mass or less, and preferably 0.05% by mass or less. Is more preferred. Within such a range, the polishing rate of the object to be polished can be further improved, and generation of surface defects on the surface of the object to be polished after polishing using the polishing composition can be further suppressed.

(Oxidant)
The polishing composition of the present invention essentially contains an oxidizing agent. The oxidizing agent according to the present invention is not particularly limited, but is preferably a peroxide. That is, according to a preferred embodiment of the present invention, the oxidizing agent is a peroxide. Specific examples of such peroxides include, but are not limited to, hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, potassium monopersulfate and oxone. And the like. The above oxidizing agents may be used alone or in combination of two or more. That is, according to a preferred embodiment of the present invention, the peroxide is a group consisting of hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, potassium monopersulfate and oxone. At least one selected from the following. As the oxidizing agent, persulfates (sodium persulfate, potassium persulfate, ammonium persulfate) and hydrogen peroxide are more preferable, and hydrogen peroxide is particularly preferable.

  The lower limit of the content (concentration) of the oxidizing agent in the polishing composition is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and more preferably 0.01% by mass or more. It is more preferred that there be. As the content of the oxidizing agent increases, there is an advantage that the polishing rate by the polishing composition is improved. The upper limit of the content (concentration) of the oxidizing agent in the polishing composition is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 1% by mass or less. preferable. As the content of the oxidizing agent decreases, the material cost of the polishing composition can be reduced, and in addition, the processing of the polishing composition after polishing is used, that is, the advantage that the load of waste liquid treatment can be reduced. Have. In addition, there is an advantage that excessive oxidation of the surface of the object to be polished hardly occurs, and the roughness of the metal surface after polishing is reduced.

  Note that since the oxidizing agent forms an oxide film on the surface of the layer containing a metal, the oxidizing agent is preferably added immediately before polishing.

(Dispersion medium)
The polishing composition of the present invention contains a dispersion medium for dispersing or dissolving each component. Here, the dispersion medium is not particularly limited, but water is preferable. From the viewpoint of suppressing the inhibition of the action of other components, water containing as little impurities as possible is more preferable. Specifically, after removing impurity ions with an ion exchange resin, foreign substances were removed through a filter. Pure water, ultrapure water, or distilled water is preferred.

(Other ingredients)
As described above, the polishing composition of the present invention essentially contains abrasive grains, an oxidizing agent, an anticorrosive, and a dispersion medium, but may contain other additives in addition to the above components. Here, the other additives are not particularly limited, and additives usually added to the polishing composition can be used. Specific examples include a pH adjuster, a complexing agent, a metal anticorrosive, a preservative, a fungicide, a reducing agent, a water-soluble polymer, and an organic solvent for dissolving a poorly soluble organic substance. The polishing composition of the present invention does not substantially contain a diquaternary compound described in, for example, JP-A-2013-42131. Further, the polishing composition of the present invention does not substantially contain an iodine compound (for example, potassium iodate) which can trigger iodine gas generation. Here, “substantially free” means that the target substance is present in a proportion of 10% by mass or less (lower limit: 0% by mass) with respect to the polishing composition, and 5% by mass. % (Lower limit: 0% by mass).

  Hereinafter, among the other additives, a pH adjuster, a complexing agent, a metal anticorrosive, a preservative, and a fungicide will be described.

(PH adjuster)
The polishing composition of the present invention may further include a pH adjuster. The pH can be adjusted by adding an appropriate amount of a pH adjuster. The pH adjuster used as necessary to adjust the pH of the polishing composition to a desired value may be any of an acid and an alkali, and may be any of an inorganic compound and an organic compound. Good. Specific examples of the acid include inorganic acids such as sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid and phosphoric acid; 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, glycol Acids, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, carboxylic acids such as citric acid and lactic acid, and methanesulfonic acid; Organic acids such as organic sulfuric acid such as ethanesulfonic acid and isethionic acid, and the like. Specific examples of alkalis include ammonia, amines such as ethylenediamine and piperazine, and quaternary ammonium salts such as tetramethylammonium and tetraethylammonium. These pH adjusters can be used alone or in combination of two or more.

  The lower limit of the pH of the polishing composition of the present invention is preferably 1.0 or more, more preferably 1.05 or more, and particularly preferably 1.1 or more. As the pH of the polishing composition increases, the handling of the polishing composition becomes easier.

  Further, the upper limit of the pH of the polishing composition is preferably 7 or less, more preferably 5 or less, and particularly preferably 4.0 or less. As the pH of the polishing composition decreases, the polishing rate of the metal to be polished increases.

(Complexing agent)
The complexing agent, which may be included in the polishing composition if necessary, has a function of chemically etching the surface of the polishing object, and more effectively improves the polishing rate of the polishing object by the polishing composition. Can be.

  Examples of usable complexing agents include, for example, inorganic acids or salts thereof, organic acids or salts thereof, nitrile compounds, amino acids, and chelating agents. These complexing agents may be used alone or in combination of two or more. As the complexing agent, a commercially available product or a synthetic product may be used.

  As the complexing agent, a salt of the inorganic acid or the organic acid may be used. In particular, when a salt of a weak acid and a strong base, a salt of a strong acid and a weak base, or a salt of a weak acid and a weak base is used, a buffering action of pH can be expected. Examples of such salts include, for example, potassium chloride, sodium sulfate, potassium nitrate, potassium carbonate, potassium tetrafluoroborate, potassium pyrophosphate, potassium oxalate, trisodium citrate, potassium (+)-tartrate, hexafluoro Potassium phosphate and the like can be mentioned.

  Specific examples of the nitrile compound include, for example, acetonitrile, aminoacetonitrile, propionitrile, butyronitrile, isobutyronitrile, benzonitrile, glutarodinitrile, methoxyacetonitrile and the like.

  Specific examples of amino acids include glycine, α-alanine, β-alanine, N-methylglycine, N, N-dimethylglycine, 2-aminobutyric acid, norvaline, valine, leucine, norleucine, isoleucine, phenylalanine, proline, sarcosine, Ornithine, lysine, taurine, serine, threonine, homoserine, tyrosine, bicine, tricine, 3,5-diiodo-tyrosine, β- (3,4-dihydroxyphenyl) -alanine, thyroxine, 4-hydroxy-proline, cysteine, methionine , Ethionine, lanthionine, cystathionine, cystine, cysteic acid, aspartic acid, glutamic acid, S- (carboxymethyl) -cysteine, 4-aminobutyric acid, asparagine, glutamine, azaserine, arginine, canavanine, cyto Phosphorus, .delta.-hydroxy - lysine, creatine, histidine, 1-methyl - histidine, 3-methyl - include histidine and tryptophan.

  Specific examples of the chelating agent include nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid, ethylenediamine-N, N, N ', N'-tetramethylenesulfonic acid, transcyclohexane Diaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol ether diaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediaminedisuccinic 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-hydroxybenzyl) ethylenediamine-N, N′-diacetic acid , 1,2-dihydroxybenzene-4,6 Such as disulfonic acid and the like.

  Among these, at least one selected from the group consisting of inorganic acids or salts thereof, carboxylic acids or salts thereof, and nitrile compounds is preferable, and from the viewpoint of the stability of the complex structure with the metal compound contained in the polishing object. , Inorganic acids or salts thereof are more preferred.

  When the polishing composition contains a complexing agent, the content (concentration) of the complexing agent is not particularly limited. For example, the lower limit of the content (concentration) of the complexing agent is not particularly limited because the effect is exhibited even with a small amount, but is preferably 0.001 g / L or more, and 0.01 g / L or more. More preferably, it is more preferably 1 g / L or more. The upper limit of the content (concentration) of the complexing agent is preferably 20 g / L or less, more preferably 15 g / L or less, and even more preferably 10 g / L or less. Within such a range, the polishing rate of the object to be polished is improved, and it is advantageous in improving the smoothness of the surface of the object to be polished after polishing using the polishing composition.

(Metal anticorrosive)
Next, the metal anticorrosive that can be included if necessary in the polishing composition is a metal anticorrosive other than the anticorrosive having the acidic functional group and the basic functional group, and prevents polishing of the polishing surface by preventing dissolution of metal. To suppress the deterioration of the surface state such as surface roughness. However, since the anticorrosive according to the present invention acts as a metal anticorrosive, the polishing composition of the present invention can sufficiently suppress and prevent the dissolution of metal without separately adding a metal anticorrosive.

  The metal corrosion inhibitor that can be used is not particularly limited, but is preferably a heterocyclic compound or a surfactant. The number of members of the heterocyclic ring in the heterocyclic compound is not particularly limited. Further, the heterocyclic compound may be a monocyclic compound or a polycyclic compound having a condensed ring. These metal anticorrosives may be used alone or in combination of two or more. As the metal anticorrosive, a commercially available product or a synthetic product may be used.

  Specific examples of the heterocyclic compound that can be used as a metal anticorrosive include, for example, pyrrole compounds, pyrazole compounds, imidazole compounds, triazole compounds, tetrazole compounds, pyridine compounds, pyrazine compounds, pyridazine compounds, pyrindine compounds, indolizine compounds, indole Compound, isoindole compound, indazole compound, purine compound, quinolidine compound, quinoline compound, isoquinoline compound, naphthyridine compound, phthalazine compound, quinoxaline compound, quinazoline compound, cinnoline compound, buteridine compound, thiazole compound, isothiazole compound, oxazole compound, iso Examples include nitrogen-containing heterocyclic compounds such as oxazole compounds and furazane compounds.

  More specifically, examples of the pyrazole compound include, for example, 1H-pyrazole, 4-nitro-3-pyrazolecarboxylic acid, 3,5-pyrazolecarboxylic acid, 3-amino-5-phenylpyrazole, -Amino-3-phenylpyrazole, 3,4,5-tribromopyrazole, 3-aminopyrazole, 3,5-dimethylpyrazole, 3,5-dimethyl-1-hydroxymethylpyrazole, 3-methylpyrazole, 1-methyl Pyrazole, 3-amino-5-methylpyrazole, 4-amino-pyrazolo [3,4-d] pyrimidine, allopurinol, 4-chloro-1H-pyrazolo [3,4-D] pyrimidine, 3,4-dihydroxy-6 -Methylpyrazolo (3,4-B) -pyridine, 6-methyl-1H-pyrazolo [3,4-b] pyridine- - amine.

  Examples of imidazole compounds include, for example, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1,2-dimethylpyrazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, benzimidazole, 5,6-dimethylbenzimidazole, 2-aminobenzimidazole, 2-chlorobenzimidazole, 2-methylbenzimidazole, 2- (1-hydroxyethyl) benzimidazole, 2-hydroxybenzimidazole, 2-phenylbenzimidazole, 2 , 5-dimethylbenzimidazole, 5-methylbenzimidazole, 5-nitrobenzimidazole and the like.

  Examples of the triazole compound include, for example, 1,2,3-triazole (1H-BTA), 1,2,4-triazole, 1-methyl-1,2,4-triazole, and methyl-1H-1,2,2. 4-triazole-3-carboxylate, 1,2,4-triazole-3-carboxylic acid, methyl 1,2,4-triazole-3-carboxylate, 1H-1,2,4-triazole-3-thiol, 3,5-diamino-1H-1,2,4-triazole, 3-amino-1,2,4-triazole-5-thiol, 3-amino-1H-1,2,4-triazole, 3-amino- 5-benzyl-4H-1,2,4-triazole, 3-amino-5-methyl-4H-1,2,4-triazole, 3-nitro-1,2,4-triazole, 3-bromo-5- Nitro- , 2,4-Triazole, 4- (1,2,4-triazol-1-yl) phenol, 4-amino-1,2,4-triazole, 4-amino-3,5-dipropyl-4H-1, 2,4-triazole, 4-amino-3,5-dimethyl-4H-1,2,4-triazole, 4-amino-3,5-dipeptyl-4H-1,2,4-triazole, 5-methyl- 1,2,4-triazole-3,4-diamine, 1H-benzotriazole, 1-hydroxybenzotriazole, 1-aminobenzotriazole, 1-carboxybenzotriazole, 5-chloro-1H-benzotriazole, 5-nitro- 1H-benzotriazole, 5-carboxy-1H-benzotriazole, 5-methyl-1H-benzotriazole, 5,6-dimethyl-1H Benzotriazole, 1- (1 ′, 2′-dicarboxyethyl) benzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole, 1- [N, N-bis (hydroxyethyl) amino Methyl] -5-methylbenzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] -4-methylbenzotriazole and the like.

  Examples of the tetrazole compound include, for example, 1H-tetrazole, 5-methyltetrazole, 5-aminotetrazole, 5-phenyltetrazole, and the like.

  Examples of indazole compounds include, for example, 1H-indazole, 5-amino-1H-indazole, 5-nitro-1H-indazole, 5-hydroxy-1H-indazole, 6-amino-1H-indazole, 6-nitro-1H -Indazole, 6-hydroxy-1H-indazole, 3-carboxy-5-methyl-1H-indazole and the like.

  Examples of indole compounds include, for example, 1H-indole, 1-methyl-1H-indole, 2-methyl-1H-indole, 3-methyl-1H-indole, 4-methyl-1H-indole, 5-methyl-1H- Indole, 6-methyl-1H-indole, 7-methyl-1H-indole, 4-amino-1H-indole, 5-amino-1H-indole, 6-amino-1H-indole, 7-amino-1H-indole, 4-hydroxy-1H-indole, 5-hydroxy-1H-indole, 6-hydroxy-1H-indole, 7-hydroxy-1H-indole, 4-methoxy-1H-indole, 5-methoxy-1H-indole, 6- Methoxy-1H-indole, 7-methoxy-1H-indole, 4-chloro-1H- Indole, 5-chloro-1H-indole, 6-chloro-1H-indole, 7-chloro-1H-indole, 4-carboxy-1H-indole, 5-carboxy-1H-indole, 6-carboxy-1H-indole, 7-carboxy-1H-indole, 4-nitro-1H-indole, 5-nitro-1H-indole, 6-nitro-1H-indole, 7-nitro-1H-indole, 4-nitrile-1H-indole, 5- Nitrile-1H-indole, 6-nitrile-1H-indole, 7-nitrile-1H-indole, 2,5-dimethyl-1H-indole, 1,2-dimethyl-1H-indole, 1,3-dimethyl-1H- Indole, 2,3-dimethyl-1H-indole, 5-amino-2,3-dimethyl-1H- Indole, 7-ethyl-1H-indole, 5- (aminomethyl) indole, 2-methyl-5-amino-1H-indole, 3-hydroxymethyl-1H-indole, 6-isopropyl-1H-indole, 5-chloro -2-methyl-1H-indole and the like.

  Among them, preferred heterocyclic compounds are triazole compounds, and in particular, 1H-benzotriazole, 5-methyl-1H-benzotriazole, 5,6-dimethyl-1H-benzotriazole, 1- [N, N-bis (hydroxy Ethyl) aminomethyl] -5-methylbenzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] -4-methylbenzotriazole, 1,2,3-triazole, and 1,2,4-triazole Is preferred. Since these heterocyclic compounds have high chemical or physical adsorption power to the surface of the object to be polished, a stronger protective film can be formed on the surface of the object to be polished. This is advantageous in improving the smoothness of the surface of the polishing target after polishing using the polishing composition of the present invention.

  Further, examples of the surfactant used as the metal anticorrosive include an anionic surfactant, a cationic surfactant, and an amphoteric surfactant.

  Examples of anionic surfactants include, for example, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfate, alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkyl ether sulfate, alkylbenzene sulfonic acid, alkyl phosphate ester , Polyoxyethylene alkyl phosphate, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, and salts thereof.

  Examples of the cationic surfactant include an alkyltrimethylammonium salt, an alkyldimethylammonium salt, an alkylbenzyldimethylammonium salt, an alkylamine salt and the like.

  Examples of amphoteric surfactants include, for example, alkyl betaines, alkylamine oxides, and the like.

  Specific examples of nonionic surfactants include, for example, polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ether, sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, and alkyl alkanol Amides are mentioned. Among them, polyoxyalkylene alkyl ether is preferred.

  Among these, preferred surfactants are polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether sulfate, alkyl ether sulfate, and alkylbenzene sulfonate. Since these surfactants have a high chemical or physical adsorption force on the surface of the object to be polished, a stronger protective film can be formed on the surface of the object to be polished. This is advantageous in improving the flatness of the surface of the object to be polished after polishing using the polishing composition of the present invention.

  When the polishing composition contains a metal anticorrosive, the content (concentration) of the metal anticorrosive is not particularly limited. For example, the lower limit of the content (concentration) of the metal anticorrosive is preferably at least 0.001 g / L, more preferably at least 0.005 g / L, and at least 0.01 g / L. More preferred. In addition, the upper limit of the content (concentration) of the metal anticorrosive is preferably 10 g / L or less, more preferably 5 g / L or less, and even more preferably 2 g / L or less. Within such a range, the dissolution of the metal can be prevented and the deterioration of the surface state such as the surface roughness of the polished surface can be suppressed.

(Preservatives and fungicides)
Further, as a preservative and a fungicide which can be contained in the polishing composition if necessary, for example, 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazoline-3 And isothiazoline preservatives such as -one, paraoxybenzoic acid esters, and phenoxyethanol. These preservatives and fungicides may be used alone or in combination of two or more.

[Method for producing polishing composition]
The method for producing the polishing composition of the present invention is not particularly limited. For example, abrasive grains, an oxidizing agent, an anticorrosive, and if necessary, other additives are stirred and mixed in a dispersion medium (for example, water). Can be obtained. As described above, the oxidizing agent promotes the formation of an oxide film on the surface of the metal-containing layer. Therefore, first, the abrasive, the anticorrosive and, if necessary, other additives are added to a dispersion medium (for example, water). ) To prepare a preliminary composition, and the oxidizing agent is preferably added to the preliminary composition immediately before polishing.

  The temperature at which the components are mixed is not particularly limited, but is preferably from 10 to 40 ° C, and heating may be performed to increase the dissolution rate. The mixing time is not particularly limited as long as the mixing can be performed uniformly.

[Polishing method and substrate manufacturing method]
As described above, the polishing composition of the present invention is suitably used for polishing a metal-containing layer (object to be polished). Therefore, the present invention also provides a polishing method for polishing a polishing object having a layer containing a metal with the polishing composition of the present invention. The present invention also provides a method for manufacturing a substrate, which includes a step of polishing a layer containing a metal (object to be polished) by the polishing method.

  As a polishing apparatus, a holder for holding a substrate or the like having an object to be polished, a motor or the like capable of changing the number of rotations, and the like are attached. A polishing device can be used.

  As the polishing pad, general nonwoven fabric, polyurethane, porous fluororesin, or the like can be used without particular limitation. The polishing pad is preferably provided with a groove processing for retaining the polishing liquid.

  Regarding the polishing conditions, for example, the rotation speed of the polishing platen is preferably 10 to 500 rpm. The pressure (polishing pressure) applied to the substrate having the object to be polished is preferably 0.5 to 10 psi. The method for supplying the polishing composition to the polishing pad is not particularly limited, either. For example, a method for continuously supplying the composition with a pump or the like is employed. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

  After the polishing, the substrate is washed in running water, and water droplets attached to the substrate are removed by a spin drier or the like and dried to obtain a substrate having a metal-containing layer.

  The polishing composition of the present invention may be a one-part type or a two-part type or other multi-part type. As described above, the oxidizing agent promotes the formation of an oxide film on the surface of the metal-containing layer. For this purpose, a first liquid containing abrasive grains, an anticorrosive, a dispersion medium (eg, water), and other additives as necessary, and a second liquid containing an oxidizing agent and, if necessary, a dispersion medium (eg, water). It is preferably a two-pack type liquid. Further, the polishing composition of the present invention may be prepared by diluting a stock solution of the polishing composition with a diluent such as water, for example, at least 10 times.

  The polishing composition of the present invention is preferably used in a metal polishing step, particularly in a tungsten polishing step. Further, the polishing composition of the present invention comprises a tungsten polishing step, a main polishing step performed to remove most of the tungsten-containing layer, and a buff polishing step of finish-polishing the tungsten-containing layer and the insulator layer. When roughly classified into, it is preferably used in the buffing step.

  The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the technical scope of the present invention is not limited only to the following examples. Unless otherwise specified, “%” and “parts” mean “% by mass” and “parts by mass”, respectively. In the following Examples, unless otherwise specified, the operation was performed under the conditions of room temperature (25 ° C.) / Relative humidity of 40 to 50% RH.

<Example>
In 1 L of pure water, the anticorrosive shown in Table 1 below was used in an amount of 0.01% by mass based on the final polishing composition, and abrasive grains (sulfonic acid-fixed colloidal silica; average primary particle diameter: 30 nm, average secondary particle diameter) : 60 nm, aspect ratio: 1.24, D90 / D10: 2.01) in an amount of 2.0% by mass with respect to the final polishing composition, and the pH of the polishing composition is adjusted to 2.1. Each polishing composition was prepared by adding a maleic acid aqueous solution (30%) so as to obtain a polishing composition. Immediately before polishing the tungsten wafer, the above polishing solution was stirred while stirring a hydrogen peroxide solution (30% by mass) as an oxidizing agent in an amount of 0.2% by mass with respect to the final polishing composition. Added to the composition. The pH of the polishing composition (liquid temperature: 25 ° C.) was confirmed with a pH meter (model number: LAQUA manufactured by Horiba, Ltd.).

  With respect to the polishing composition obtained above, the polishing rate (Removal Rate) (Å / min), the etching rate (Etching Rate) (Å / min), and the surface roughness (RMS) were evaluated according to the following methods. The results are shown in Table 1 below.

<Measurement of polishing rate (Removal Rate)>
An object to be polished is polished under the following polishing conditions using each polishing composition. The thickness (film thickness) of the object to be polished before and after polishing was measured with a manual sheet resistor (VR-120, manufactured by Hitachi Kokusai Electric Inc.). The polishing rate (Removal Rate) (Å / min) was determined by dividing the difference in thickness (film thickness) of the object before and after polishing by the polishing time according to the following (method of calculating polishing rate). Note that a tungsten wafer (size: 32 mm × 32 mm) was used as an object to be polished.

(Polishing conditions)
Polishing machine: Single-sided CMP polishing machine (ENGIS)
Polishing pad: polyurethane pad (IC1010: manufactured by Rohm and Haas)
Pressure: 2.0 psi
Platen (platen) rotation speed: 70 rpm
Head (carrier) rotation speed: 70 rpm
Flow rate of polishing composition: 150 ml / min
Polishing time: 60 sec
(Method of calculating polishing rate)
The polishing rate (polishing rate) (Å / min) is calculated by the following equation (1).

<Measurement of Etching Rate>
An etching test was performed by the following operation. That is, the polishing object was immersed in a sample container in which 300 mL of each polishing composition was stirred at 300 rpm for 10 minutes. After immersion, the wafer was washed with pure water for 30 seconds and dried by air blow drying using an air gun. The thickness (film thickness) of the object to be polished before and after the etching test is measured with a manual sheet resistor (VR-120, Hitachi Kokusai Electric). The etching rate (Å / min) was determined by dividing the difference in the thickness (film thickness) of the object before and after the etching test by the etching test time according to the following (method for calculating the etching rate). Note that a tungsten wafer (size: 32 mm × 32 mm) was used as an object to be polished.

(Method of calculating etching rate)
The etching rate (etching rate) (Å / min) is calculated by the following equation (2).

<Measurement of surface roughness (RMS)>
An object to be polished was polished using the polishing composition in the same manner as in the above [Measurement of polishing rate (Removal Rate)]. The surface roughness (RMS) of the polished surface of the polished object after polishing was measured using a scanning probe microscope (SPM). Note that NANO-NAVI2 manufactured by Hitachi High-Technologies Corporation was used as the SPM. The cantilever used was SI-DF40P2. The measurement was performed three times at a scanning frequency of 0.86 Hz, X: 512 pt, and Y: 512 pt, and the average value thereof was taken as the surface roughness (RMS).

  In the table, POE means polyoxyethylene, and the number after POE means the number of moles of ethylene oxide added. For example, POE (130) isotridecyl ether ammonium phosphate refers to a compound in which the number of moles of added ethylene oxide is 130. "C12-15" means an alkyl group having from 12 to 15 carbon atoms and a mixture thereof.

  From the results in Table 1 above, a polishing composition containing no anticorrosive (Comparative Example 1) or a polishing composition containing an anticorrosive containing neither an acidic functional group nor a basic functional group at the same time (Comparative Example) In Comparative Examples 2 to 8, it can be seen that the etching rate is high and the surface roughness of the object to be polished is also at a high level. On the other hand, it can be seen that the use of the polishing composition containing the anticorrosive having an acidic functional group and a basic functional group (Examples 1 to 11) suppressed the etching rate of the metal (tungsten) substrate. It is also shown that polishing with the polishing composition of the present invention can provide a substrate having a polished surface with a smaller surface roughness (RMS) (that is, excellent in smoothness). Furthermore, it was also found that the larger the mole number of ethylene oxide of the anticorrosive contained in the polishing composition, the higher the polishing rate while the lower the etching rate.

Claims (9)

A polishing composition used for polishing a polishing target having a layer containing tungsten ,
Abrasive grains and an oxidation agent, see containing a dispersion medium, and a corrosion inhibitor having an acidic functional group and basic functional groups, wherein the anticorrosive is a compound represented by the following formula (1):

In the formula (1), R ¹ and R ² are each independently a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 8 to 16 carbon atoms;
Y ¹ and Y ² are each independently a single bond or a group represented by the following formula (i), and at least one of Y ¹ and Y ² is a group represented by the following formula (i);

In Formula (i), R ³ is an alkylene group having 2 to 6 carbon atoms, a plurality of R ³ may be the same or different, n is an integer of 2 to 200, and * is , A position bonding to R ¹ or R ² in the formula (1) ,
X ⁺ is an ammonium ion, a primary ammonium ion, a secondary ammonium ion, a tertiary ammonium ion, or a quaternary ammonium ion;
A polishing composition , which is a compound represented by the formula: The polishing composition according to claim 1, wherein the anticorrosive has an acid value of 5 to 150 mgKOH / g and an amine value of 5 to 150 mgKOH / g. It said oxidizing agent is a peroxide, polishing composition according to claim 1 or 2. The peroxide is at least one selected from the group consisting of hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, potassium monopersulfate and oxone. The polishing composition according to claim 3 . The polishing composition according to any one of claims 1 to 4 , further comprising a pH adjuster. The polishing composition according to any one of claims 1 to 5, wherein the abrasive grains are silica fixed with an organic acid. A step of preparing a preliminary composition by mixing abrasive grains and an anticorrosive with a dispersion medium, and
  Adding an oxidizing agent to the preliminary composition immediately before polishing,
The method for producing a polishing composition according to any one of claims 1 to 6, comprising: A polishing method for polishing a polishing target having a layer containing tungsten with the polishing composition according to claim 1. A method for manufacturing a substrate, comprising a step of polishing by the polishing method according to claim 8.