JP2022028258A - Abrasive, two-part abrasive and polishing method - Google Patents

Abstract

To provide an abrasive that can give a polishing rate of silicon oxide that is equal to or lower than a polishing rate of silicon nitride, a two-part abrasive for obtaining the abrasive, and a polishing method that uses the abrasive or the two-part abrasive.SOLUTION: An abrasive contains abrasive grains, an amine with a first acid dissociation constant pKa of 10.0 or more, and water. There is also provided a two-part abrasive for obtaining the abrasive that contains first liquid containing the abrasive grains and second liquid containing the amine. There is also provided a polishing method for polishing a to-be-polished face with the abrasive, or an abrasive that is a mixture of the first liquid and second liquid of the two-part abrasive.SELECTED DRAWING: None

Description

The present invention relates to an abrasive, a two-component abrasive and a polishing method.

In recent years, new microfabrication techniques have been developed along with the high integration and high performance of semiconductor integrated circuits (Large-Scale Integration, hereinafter referred to as "LSI"). Chemical mechanical polishing (hereinafter referred to as "CMP") method is one of them. The CMP method is a technique frequently used in the LSI manufacturing process (particularly, flattening of an insulating film in a multilayer wiring forming process, formation of a metal plug, formation of embedded wiring, etc.).

As the conductive material used as the wiring material, a metal material containing copper (Cu) having a low resistance (copper simple substance, copper alloy, etc.) is used in order to improve the performance of the LSI. Conventionally, in the dry etching method frequently used for forming aluminum (Al) alloy wiring, it is difficult to finely process the conductive material part (for example, a metal film) containing copper, so that the wiring containing copper is formed. The so-called damascene method is mainly adopted for. In the damascene method, a conductive substance (for example, a metal material containing copper) is deposited on the surface of an insulating material portion (for example, an interlayer insulating film) having a groove formed on the surface in advance, and the conductive substance is embedded in the groove. Form a conductive material part (for example, a metal film). Next, the portion of the conductive substance portion other than the groove in which the conductive substance is embedded is removed by the CMP method to form an embedded wiring.

Further, at present, a metal material containing tungsten (W) is used in a plurality of applications such as a contact material, a plug material, a via material, and a gate material. In forming the contact plug or the like, a process similar to the process used for forming the wiring is adopted.

By the way, LSI is moving toward higher integration and higher performance. Along with this, miniaturization is also required for embedded wiring by the damascene method. However, copper and tungsten used as wiring materials, contact materials, etc. have a problem that the electric resistance becomes large and the wiring life is shortened with the miniaturization. Therefore, cobalt (Co), which has good embedding, has lower electrical resistance than copper and tungsten, and is less likely to cause electromigration (EM) in which metal ions diffuse and reach the insulating material, is used as a wiring material, contact material, etc. There is a movement to use it (see, for example, Patent Documents 1 and 2 below).

International Publication No. 2018/159530 U.S. Pat. No. 9735031

In the CMP method, the silicon oxide portion and the silicon nitride portion may be polished at the same time (see FIG. 1 to be described later). However, as a result of the studies by the present inventors, in the CMP method using a conventional abrasive, when the silicon oxide portion and the silicon nitride portion are polished at the same time, the polishing speed of silicon oxide is higher than the polishing speed of silicon nitride. It has been clarified that the silicon oxide portion becomes large and the silicon oxide portion is excessively polished, so that dents called dishing, recess, loss, etc. (hereinafter collectively referred to as “dishes”) are generated in the silicon oxide portion.

One aspect of the present invention is to provide an abrasive capable of obtaining a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. And. Another aspect of the present invention is to provide a two-component abrasive for obtaining the abrasive. Another aspect of the present invention is to provide a polishing method using the abrasive or the two-component abrasive.

The present inventors have found that the above problems can be solved by using an abrasive containing a specific amine.

One aspect of the present invention provides an abrasive containing abrasive grains, an amine having a first acid dissociation constant pKa of 10.0 or more, and water.

According to such an abrasive, it is possible to obtain a polishing speed equal to or lower than the polishing speed of silicon nitride as the polishing speed of silicon oxide.

Another aspect of the present invention is a two-component abrasive for obtaining the abrasive, which has a first liquid containing the abrasive grains and a second liquid containing the amine. A liquid abrasive is provided.

Another aspect of the present invention is to polish the surface to be polished with the above-mentioned polishing agent or a polishing agent obtained by mixing the above-mentioned first liquid and the above-mentioned second liquid of the above-mentioned two-component polishing agent. To provide a polishing method.

According to one aspect of the present invention, it is possible to provide an abrasive capable of obtaining a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. Can be done. According to another aspect of the present invention, there is provided a two-component abrasive for obtaining the abrasive. According to another aspect of the present invention, it is possible to provide a polishing method using the polishing agent or the two-component polishing agent.

It is sectional drawing which shows the polishing method which concerns on one Embodiment of this invention.

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

<Definition>
As used herein, the term "polishing rate" means the rate at which the material to be polished is removed by polishing (for example, the amount of reduction in the thickness of the material to be polished per hour; Removal Rate). The term "process" includes not only independent processes but also processes in which the intended action of the process is achieved, although it is not clearly distinguishable from other processes. The term "membrane" includes not only a structure having a shape formed on the entire surface when observed as a plan view, but also a structure having a shape partially formed. The numerical range indicated by using "-" indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively. "A or more" in the numerical range means A and a range exceeding A. "A or less" in the numerical range means A and a range less than A. Within the numerical range described stepwise herein, the upper or lower limit of the numerical range at one stage may be optionally combined with the upper or lower limit of the numerical range at another stage. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "A or B" may include either A or B, and may include both. Unless otherwise specified, the materials exemplified in the present specification may be used alone or in combination of two or more. The content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.

<Abrasive>
The abrasive according to the present embodiment is at least an abrasive grain (hereinafter referred to as "abrasive grain") and an amine having a first acid dissociation constant pKa of 10.0 or more (hereinafter referred to as "amine A"). And water. The polishing agent according to this embodiment can be used as a polishing agent for CMP.

According to the polishing agent according to the present embodiment, it is possible to obtain a polishing speed equal to the polishing speed of silicon nitride or a polishing speed lower than the polishing speed of silicon nitride as the polishing speed of silicon oxide. A polishing rate ratio of less than 2.0 can be obtained as the polishing rate ratio of silicon oxide to (polishing rate of silicon oxide / polishing rate of silicon nitride). According to the polishing agent according to the present embodiment, when the silicon oxide portion and the silicon nitride portion are polished at the same time, it is possible to suppress the occurrence of dishing in the silicon oxide portion due to excessive polishing of the silicon oxide portion. According to the polishing agent according to the present embodiment, in polishing a blanket wafer and a pattern wafer, the polishing speed of silicon oxide is equal to the polishing speed of silicon nitride or lower than the polishing speed of silicon nitride. Obtainable. According to the polishing agent according to the present embodiment, while obtaining a good polishing rate of silicon nitride, the polishing rate of silicon oxide is equal to or lower than the polishing rate of silicon nitride. You can get speed.

According to one aspect of the polishing agent according to the present embodiment, it is possible to obtain a polishing speed equal to or lower than the polishing speed of cobalt as the polishing speed of silicon oxide, and it is possible to obtain a polishing speed lower than the polishing speed of cobalt. A polishing rate ratio of less than 2.0 can be obtained as the polishing rate ratio of silicon oxide (polishing rate of silicon oxide / polishing rate of cobalt) with respect to. With such an abrasive, it is possible to prevent silicon oxide from being excessively polished with respect to cobalt. In addition to this, as described above, since it is possible to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide, silicon oxide can be used. Excessive polishing with respect to silicon nitride and cobalt can be suppressed. According to one aspect of the polishing agent according to the present embodiment, the polishing rate of silicon oxide is equal to or lower than the polishing rate of cobalt while obtaining a good polishing rate of cobalt. You can get speed. Examples of the material to be polished containing cobalt include elemental cobalt, cobalt alloys, cobalt oxides, cobalt alloy oxides and the like.

The abrasive according to this embodiment may be used for polishing the surface to be polished containing silicon oxide and silicon nitride. According to the present embodiment, it is possible to provide an application of an abrasive for polishing a surface to be polished containing silicon oxide and silicon nitride (for example, a surface to be polished having a silicon oxide portion and a silicon nitride portion). The abrasive according to this embodiment may be used for polishing a surface to be polished containing cobalt. According to the present embodiment, it is possible to provide the application of the polishing agent to the polishing of the surface to be polished containing cobalt (the surface to be polished having a cobalt-containing portion), and it is possible to provide the surface to be polished containing silicon oxide and cobalt (the surface to be polished). It is possible to provide an application of a polishing agent for polishing a silicon oxide portion and a surface to be polished having a cobalt-containing portion), and it is possible to provide a surface to be polished (silicon oxide portion, silicon nitride portion) containing silicon oxide, silicon nitride and cobalt. And the application of the polishing agent to the polishing of the surface to be polished having a cobalt-containing portion) can be provided.

(Abrasion grain)
The abrasive according to this embodiment contains abrasive grains. As used herein, the term "abrasive particles" means a collection of a plurality of particles, but for convenience, one particle constituting the abrasive grains may be referred to as an abrasive grain. The abrasive grains may contain one or more kinds of particles.

Examples of the constituent materials of the abrasive grains include inorganic substances such as silica, alumina, zirconia, ceria, titania, germania, and silicon carbide; organic substances such as polystyrene, polyacrylic acid, and polyvinyl chloride; and modified products thereof. Examples of the abrasive grains containing the modified product include those obtained by modifying the surface of particles containing silica, alumina, ceria, titania, zirconia, germania and the like with an alkyl group.

The abrasive grains preferably contain silica from the viewpoint that defects such as scratches are unlikely to occur on the surface to be polished (the surface of the wiring portion, the surface of the liner portion, the surface of the insulating material portion, etc.). The content of silica in the abrasive grains is 50% by mass or more, 70% by mass or more, based on the total amount of the abrasive grains (the whole abrasive grains contained in the abrasive or the whole one particle constituting the abrasive grains). It may be 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more. The abrasive grains are made of silica (substantially 100% by mass of the abrasive grains contained in the abrasive is silica, or substantially 100% by mass of one particle constituting the abrasive grains is silica). May be.

Examples of the abrasive grains containing silica include amorphous silica, crystalline silica, fused silica, spherical silica, synthetic silica, hollow silica, colloidal silica and the like. The abrasive grains preferably contain colloidal silica from the viewpoint that defects such as scratches are less likely to occur.

The average secondary particle diameter of the abrasive grains is preferably 150 nm or less, more preferably 120 nm or less, still more preferably 100 nm, from the viewpoint that excellent polishing scratch characteristics are easily obtained (defects such as scratches are unlikely to occur). It is less than or equal to, particularly preferably 90 nm or less, extremely preferably 80 nm or less, and very preferably 70 nm or less. The average secondary particle diameter of the abrasive grains is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, and particularly preferably 20 nm, from the viewpoint that an excellent polishing rate of cobalt can be easily obtained. The above is extremely preferably 30 nm or more, very preferably 40 nm or more, and even more preferably 50 nm or more. From these viewpoints, the average secondary particle diameter of the abrasive grains is preferably 5 to 150 nm, more preferably 5 nm to 120 nm, still more preferably 10 to 100 nm, and particularly preferably 15 nm to 90 nm. It is extremely preferably 20 to 90 nm, very preferably 30 to 80 nm, even more preferably 40 to 80 nm, and even more preferably 50 to 70 nm. The average secondary particle size of the abrasive grains can be measured using a light diffraction / scattering type particle size distribution meter (for example, DELSA MAX PRO manufactured by BECKMAN COULTER). Specifically, the average secondary particle diameter of the abrasive grains can be measured by the method described in Examples described later.

The content of the abrasive grains is preferably 0.01% by mass or more based on the total mass of the polishing agent, from the viewpoint that the ability to remove the cobalt-containing portion is excellent and an excellent polishing rate of cobalt can be easily obtained. It is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, extremely preferably 1.0% by mass or more, and very preferably. Is 2.0% by mass or more, and even more preferably 3.0% by mass or more. The content of the abrasive grains is preferably 20% by mass or less, more preferably 20% by mass or less, based on the total mass of the abrasive, from the viewpoint that good dispersion stability of the abrasive grains can be easily obtained and defects such as scratches are unlikely to occur. Is 15% by mass or less, more preferably 10% by mass or less, particularly preferably 8.0% by mass or less, extremely preferably 6.0% by mass or less, and very preferably 5.0% by mass. % Or less, and even more preferably 4.0% by mass or less. From these viewpoints, the content of the abrasive grains is preferably 0.01 to 20% by mass, more preferably 0.05 to 15% by mass, and further preferably 0, based on the total mass of the abrasive. .1 to 10% by mass, particularly preferably 0.5 to 8.0% by mass, extremely preferably 1.0 to 6.0% by mass, and very preferably 2.0 to 5.0% by mass. It is% by mass, more preferably 3.0 to 4.0% by mass.

(Amine)
The abrasive according to this embodiment contains an amine A having a first acid dissociation constant pKa of 10.0 or more. When the polishing agent contains amine A, it is possible to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. The present inventor presumes that the mechanism for obtaining such an effect is that amine A strongly coordinates silicon oxide to suppress polishing by abrasive grains. However, the mechanism is not limited to the content.

The acid dissociation constant (pKa) means the negative common logarithm (logarithm of the inverse) of the equilibrium constant Ka in the dissociation reaction in which hydrogen ions are released from the acid. The acid dissociation constant of a base is the acid dissociation constant of the conjugate acid of the base. When an amine having a plurality of pKa is used as the amine A, the acid dissociation constant (pKa1) of the first stage is referred to as "first acid dissociation constant pKa". The amine A may be an amine having a single pKa, and in this case, the single pKa is referred to as "first acid dissociation constant pKa". As the value of pKa (pKa1), for example, Chemical Handbook, Basic Edition II (Revised 5th Edition, Maruzen Co., Ltd.) can be referred to.

The pKa of amine A is preferably 10.2 or more as the polishing rate of silicon oxide from the viewpoint of easily obtaining a polishing rate equal to the polishing rate of silicon nitride or a polishing rate lower than the polishing rate of silicon nitride. It is more preferably 10.4 or more, further preferably 10.5 or more, and particularly preferably 10.6 or more. The pKa of amine A is preferably 15.0 or less as the polishing rate of silicon oxide from the viewpoint of easily obtaining a polishing rate equal to the polishing rate of silicon nitride or a polishing rate lower than the polishing rate of silicon nitride. It is more preferably 13.0 or less, further preferably 12.0 or less, particularly preferably 11.5 or less, extremely preferably 11.0 or less, and very preferably 10.8 or less. , Even more preferably 10.6 or less. From these viewpoints, the pKa of amine A is preferably 10.0 to 15.0, more preferably 10.2 to 13.0, and even more preferably 10.5-11.5.

Examples of amine A include aliphatic amines, aromatic amines, and heterocyclic amines. Amine A corresponds to an aliphatic amine (hereinafter referred to as amine A) from the viewpoint that it is easy to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. The aliphatic amine is preferably contained (referred to as "aliphatic amine A"). Amine A (aliphatic amine A or the like) may have a substituent such as a hydroxy group. Amine A can be used alone or in combination of two or more.

Amine A is bonded to the nitrogen atom of the amine A from the viewpoint that it is easy to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. As the hydrocarbon group, it is preferable to have a hydrocarbon group having the following carbon atoms. The hydrocarbon group has 1 or more carbon atoms, preferably 2 or more, more preferably 3 or more, still more preferably 4 or more, and particularly preferably 5 or more. The number of carbon atoms of the hydrocarbon group is preferably 15 or less, more preferably 10 or less, still more preferably 8 or less, particularly preferably 6 or less, and extremely preferably 5 or less. From these viewpoints, the number of carbon atoms of the hydrocarbon group is preferably 1 to 15, more preferably 2 to 10, and even more preferably 3 to 8. The number of carbon atoms of the hydrocarbon group may be 4 or less, 3 or less, or 2 or less. When a plurality of hydrocarbon groups are bonded to the nitrogen atom, it is preferable that the total carbon number of all the bonded hydrocarbon groups satisfies the above numerical range.

Amine A may include at least one selected from the group consisting of primary amines, secondary amines, tertiary amines and quaternary amines. Amine A is composed of a primary amine and a secondary amine from the viewpoint that it is easy to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. It is preferable to contain at least one selected from the group, and it is more preferable to contain a primary amine (hereinafter, the primary amine corresponding to amine A is referred to as "primary amine A"). Amine A is an aliphatic primary amine (aliphatic amine and) from the viewpoint that it is easy to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. It is preferable to contain at least one selected from the group consisting of a primary amine (compound) and an aliphatic secondary amine (a compound which is an aliphatic amine and a secondary amine), and preferably contains an aliphatic primary amine. Is more preferable.

Examples of amine A include ethylamine, diethylamine, dimethylamine, amylamine, butylamine, t-amylamine, t-butylamine, isobutylamine, isoamylamine, diisobutylamine, 3-amino-1-propanol, 1,1,3,3-tetra. Examples thereof include methylbutylamine. Amine A is a t-amylamine, t-butylamine, isobutylamine, from the viewpoint that it is easy to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. It preferably contains at least one selected from the group consisting of isoamylamine, diisobutylamine and 3-amino-1-propanol, and preferably contains at least one selected from the group consisting of t-amylamine, t-butylamine, isobutylamine and isoamylamine. It is more preferable, and it is further preferable to contain isoamylamine.

The molecular weight of amine A is preferably 40 or more, more preferably, from the viewpoint that the polishing rate of silicon oxide can easily obtain a polishing rate equal to the polishing rate of silicon nitride or a polishing rate lower than the polishing rate of silicon nitride. Is 50 or more, more preferably 60 or more, particularly preferably 70 or more, and extremely preferably 80 or more. The molecular weight of amine A is preferably 300 or less, more preferably, from the viewpoint that the polishing rate of silicon oxide can easily obtain a polishing rate equal to the polishing rate of silicon nitride or a polishing rate lower than the polishing rate of silicon nitride. Is 200 or less, more preferably 150 or less, and particularly preferably 100 or less. From these viewpoints, the molecular weight of amine A is preferably 40 to 300, more preferably 50 to 200, still more preferably 60 to 150, and particularly preferably 70 to 100.

The content of amine A is from the viewpoint that it is easy to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide, and amine A is strong against silicon oxide. From the viewpoint that the polishing rate of silicon nitride is easily suppressed by coordinating to silicon nitride while coordinating, it is preferably 0.005% by mass or more, more preferably 0.01, based on the total mass of the polishing agent. It is 0% by mass or more, more preferably 0.05% by mass or more, particularly preferably 0.10% by mass or more, extremely preferably 0.20% by mass or more, and very preferably 0.20% by mass. %, More preferably 0.22% by mass or more, still more preferably 0.24% by mass or more, particularly preferably 0.25% by mass or more, and extremely preferably 0.28% by mass. % Or more, and very preferably 0.30% by mass or more. The content of amine A is from the viewpoint that the abrasive grains are less likely to aggregate and the storage stability of the abrasive is likely to be improved, and the polishing speed of silicon oxide is the same as the polishing speed of silicon nitride, or nitriding. From the viewpoint that a polishing rate lower than the polishing rate of silicon can be easily obtained, it is preferably 1% by mass or less, more preferably 0.75% by mass or less, still more preferably 0.50, based on the total mass of the abrasive. It is 0% by mass or less, and particularly preferably 0.35% by mass or less. From these viewpoints, the content of amine A is preferably 0.005 to 1% by mass, more preferably 0.01 to 0.75% by mass, still more preferably, based on the total mass of the polishing agent. Is 0.05 to 0.50% by mass, particularly preferably 0.10 to 0.35% by mass, and extremely preferably more than 0.20% by mass and 0.35% by mass or less. The content of amine A is preferably 0.30% by mass or less, more preferably 0.25% by mass, based on the total mass of the abrasive, from the viewpoint that excellent polishing rates of silicon oxide and silicon nitride can be easily obtained. % Or less, more preferably 0.20% by mass or less. From the same viewpoint, it is preferable that the content of the aliphatic amine A satisfies the above numerical range regarding the content of the amine A based on the total mass of the abrasive. From the same viewpoint, it is preferable that the content of the primary amine A satisfies the above numerical range regarding the content of the amine A based on the total mass of the abrasive.

The mass ratio R1 of the content of amine A to the content of abrasive grains R1 (content of amine A / content of abrasive grains) is the polishing rate of silicon oxide, which is equivalent to the polishing rate of silicon nitride, or From the viewpoint of easily obtaining a polishing speed lower than the polishing speed of silicon nitride, the range is preferably as follows. The mass ratio R1 is preferably 5 or less, more preferably 3 or less, still more preferably 1 or less, particularly preferably 0.8 or less, extremely preferably 0.6 or less, and very very. It is preferably 0.4 or less, further preferably 0.2 or less, still more preferably 0.15 or less, particularly preferably 0.13 or less, and extremely preferably 0.12 or less. It is very preferably 0.1 or less. The mass ratio R1 is preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more, particularly preferably 0.04 or more, and extremely preferably 0.05. The above is very preferably 0.06 or more, even more preferably 0.08 or more, and further preferably 0.09 or more. From these viewpoints, the mass ratio R1 is preferably 0.01 to 5, more preferably 0.02 to 3, and even more preferably 0.03 to 1. The mass ratio R1 is preferably 0.08 or less, more preferably 0.07 or less, still more preferably 0.065 or less, from the viewpoint that excellent polishing rates of silicon oxide and silicon nitride can be easily obtained. .. From the same viewpoint, the mass ratio of the content of the aliphatic amine A to the content of the abrasive grains preferably satisfies the above numerical range with respect to the mass ratio R1. From the same viewpoint, it is preferable that the mass ratio of the content of the primary amine A to the content of the abrasive grains satisfies the above numerical range with respect to the mass ratio R1.

The abrasive according to the present embodiment may contain an amine having a first acid dissociation constant pKa of less than 10.0 (hereinafter referred to as "amine B"). The content of amine B is based on the total mass of the polishing agent from the viewpoint that it is easy to obtain a polishing rate equal to or lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. It is preferably 1% by mass or less, more preferably 0.1% by mass or less, further preferably 0.01% by mass or less, and particularly preferably 0.001% by mass or less. The abrasive may be in an embodiment that does not substantially contain amine B (the content of amine B contained in the abrasive is substantially 0% by mass).

The mass ratio of the content of amine B to the content of amine A (content of amine B / content of amine A) is the polishing rate of silicon oxide, which is equivalent to the polishing rate of silicon nitride, or nitrided. From the viewpoint of easily obtaining a polishing speed lower than the polishing speed of silicon, it is preferably 1 or less, more preferably 0.1 or less, still more preferably 0.01 or less, and particularly preferably 0.001 or less. ..

The content of aliphatic amine A in the amine contained in the polishing agent (standard: total mass of amine) and / or the content of primary amine A in the amine contained in the polishing agent (standard: total mass of amine). Is preferably 80% by mass or more, more preferably 90, from the viewpoint that it is easy to obtain a polishing speed equal to the polishing speed of silicon nitride or a polishing speed smaller than the polishing speed of silicon nitride as the polishing speed of silicon oxide. It is 9% by mass or more, more preferably 95% by mass or more, particularly preferably 98% by mass or more, and extremely preferably 99% by mass or more. The amine contained in the abrasive may be substantially composed of the aliphatic amine A (substantially 100% by mass of the amine contained in the abrasive is the aliphatic amine A). The amine contained in the abrasive may be substantially composed of the primary amine A (substantially 100% by mass of the amine contained in the abrasive is the primary amine A).

(Oxidant)
The abrasive according to the present embodiment may further contain an oxidizing agent (oxidizing agent component, metal oxidizing agent). When the polishing agent contains an oxidizing agent, the metal material (cobalt or the like) is sufficiently oxidized, and it is easy to obtain a good polishing rate of the metal material and to suppress excessive corrosion of the metal material (cobalt or the like).

Examples of the oxidizing agent include hydrogen peroxide, potassium periodate, ozone and the like. The oxidizing agent preferably contains hydrogen peroxide from the viewpoint of easily controlling the polishing rate of the metal material (cobalt or the like). The oxidizing agent may be used alone or in combination of two or more.

The content of the oxidizing agent is such that the metal material (cobalt, etc.) is easily sufficiently oxidized, a better polishing rate of the metal material can be easily obtained, and excessive corrosion of the metal material (cobalt, etc.) can be further suppressed. Based on the total mass of the polishing agent, it is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass. It is 0% by mass or more, extremely preferably 0.8% by mass or more, very preferably 1.0% by mass or more, and even more preferably 1.2% by mass or more. The content of the oxidizing agent is preferably 3.0% by mass or less, more preferably 2. It is 0% by mass or less, more preferably 1.5% by mass or less, and particularly preferably 1.2% by mass or less. From these viewpoints, the content of the oxidizing agent is preferably 0.1 to 3.0% by mass, more preferably 0.2 to 2.0% by mass, based on the total mass of the polishing agent. More preferably, it is 0.3 to 1.2% by mass. The content of the oxidizing agent is 1.0% by mass or less, 0.9% by mass or less, 0.7% by mass or less, 0.6% by mass or less, or 0.5% by mass or less based on the total mass of the polishing agent. May be.

The mass ratio R2 (oxidant content / abrasive grain content) of the oxidant content to the abrasive grain content is as follows from the viewpoint of easily obtaining a better polishing rate of the metal material (cobalt, etc.). It is preferably in the range. The mass ratio R2 is preferably 5 or less, more preferably 3 or less, still more preferably 1 or less, particularly preferably 0.8 or less, extremely preferably 0.6 or less, and very very. It is preferably 0.4 or less. The mass ratio R2 is preferably 0.01 or more, more preferably 0.05 or more, still more preferably 0.1 or more, particularly preferably 0.15 or more, and extremely preferably 0.2. The above is very preferably 0.3 or more, and even more preferably 0.35 or more. From these viewpoints, the mass ratio R2 is preferably 0.01 to 5. The mass ratio R2 may be 0.3 or less or 0.2 or less.

The mass ratio R3 (oxidant content / amine A content) of the oxidant content to the amine A content is in the following range from the viewpoint of easily obtaining a good polishing rate of a metal material (cobalt, etc.). Is preferable. The mass ratio R3 is preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, particularly preferably 8 or less, extremely preferably 7 or less, and very preferably 6 or less. It is even more preferably 5 or less. The mass ratio R3 is preferably 0.5 or more, more preferably 1 or more, still more preferably 1.5 or more, particularly preferably 2 or more, extremely preferably 3 or more, and very much. It is preferably 4 or more. From these viewpoints, the mass ratio R3 is preferably 0.5 to 20. The mass ratio R3 may be 4 or less or 3 or less. The mass ratio R3 may be 5 or more or 6 or more.

(Metal corrosion inhibitor)
The abrasive according to the present embodiment may further contain a metal anticorrosive agent (excluding amine A). The metal corrosion inhibitor, for example, reacts with a metal material to form a chelate complex to prevent the surface to be polished containing the metal material (cobalt, etc.) from being excessively corroded, and provides a protective film against the metal material. It is a compound that can be formed. Since the polishing agent contains a metal anticorrosion agent, it is easy to suppress the etching of the metal material by forming a protective film against the metal material and reduce the roughness of the surface to be polished containing the metal material.

As the metal anticorrosive agent, a known compound having an anticorrosive action against a metal material can be used. Examples of the metal anticorrosion agent include triazole compounds, imidazole compounds, pyrimidine compounds, guanidine compounds, thiazole compounds, pyrazole compounds and the like. These "compounds" are a general term for compounds having a skeleton thereof, and for example, "triazole compound" means a compound having a triazole skeleton. The metal corrosion inhibitor may be used alone or in combination of two or more.

Specific examples of the triazole compound include 1,2,3-triazole, benzotriazole, 1-hydroxybenzotriazole, bis [(1-benzotriazole) methyl] phosphonic acid, and 5-methyl-1H-benzotriazole (5-methyl). Benzotriazole) and the like.

Specific examples of the imidazole compound include 2-methylimidazole, 2-aminoimidazole and the like.

Specific examples of the pyrimidine compound include pyrimidine, 1,2,4-triazolo [1,5-a] pyrimidine and the like.

Specific examples of the guanidine compound include 1,3-diphenylguanidine, 1-methyl-3-nitroguanidine and the like.

Specific examples of the thiazole compound include 2-mercaptobenzothiazole and 2-aminothiazole.

Specific examples of the pyrazole compound include 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole and the like.

The metal anticorrosive agent preferably contains a triazole compound from the viewpoint of easily suppressing corrosion of the surface to be polished containing a metal material, and contains 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H. It is more preferable to contain at least one selected from the group consisting of -1,2,4-triazole, 1-hydroxybenzotriazole and 5-methyl-1H-benzotriazole.

The content of the metal anticorrosion agent is preferably 0.0005% by mass or more, more preferably 0.001 based on the total mass of the polishing agent, from the viewpoint of easily suppressing corrosion of the surface to be polished containing the metal material. It is 0% by mass or more, more preferably 0.003% by mass or more, particularly preferably 0.005% by mass or more, extremely preferably 0.01% by mass or more, and very preferably 0.03% by mass. % Or more, and even more preferably 0.05% by mass or more. The content of the metal anticorrosion agent is preferably 0.5% by mass or less, more preferably 0.3, based on the total mass of the polishing agent, from the viewpoint of easily suppressing corrosion of the surface to be polished containing the metal material. It is 0% by mass or less, more preferably 0.15% by mass or less, particularly preferably 0.1% by mass or less, extremely preferably 0.09% by mass or less, and very preferably 0.08% by mass. % Or less, and even more preferably 0.07% by mass or less. From these viewpoints, the content of the metal anticorrosion agent is preferably 0.0005 to 0.5% by mass, more preferably 0.001 to 0.3% by mass, based on the total mass of the polishing agent. It is more preferably 0.003 to 0.15% by mass, particularly preferably 0.005 to 0.1% by mass, extremely preferably 0.01 to 0.09% by mass, and very preferably. It is 0.03 to 0.08% by mass, and even more preferably 0.05 to 0.07% by mass.

(PH regulator)
The abrasive according to the present embodiment may further contain a pH adjuster in order to adjust the pH of the abrasive. As the pH adjuster, an organic acid, a basic component (excluding amine A and a metal anticorrosive agent) and the like can be used. By containing the pH adjuster, the abrasive can adjust the pH of the abrasive to a desired value while adjusting the content of amine A. One type of pH regulator may be used alone, or two or more types may be mixed. The abrasive may contain a compound corresponding to the pH adjuster for purposes other than adjusting the pH.

The abrasive according to this embodiment may contain an organic acid. Specific examples of organic acids include monocarboxylic acids such as acetic acid, propionic acid and benzoic acid; malonic acid, succinic acid, citric acid, malic acid, oxalic acid, tartrate acid, picolinic acid, phthalic acid, adipic acid, glutaric acid and the like. Dicarboxylic acids; examples include amino acids such as alanine, glycine, leucine, isoleucine, asparagine, aspartic acid, arginine and cysteine. As the organic acid, one kind may be used alone, or two or more kinds may be mixed. The organic acid preferably contains citric acid from the viewpoint of easily preventing aggregation of abrasive grains.

The abrasive according to this embodiment may contain a basic component. Specific examples of the base component include inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonia. One type of base component may be used alone, or two or more types may be mixed. The base component preferably contains potassium hydroxide (KOH) from the viewpoint of easily preventing aggregation of abrasive grains.

The content of the organic acid is based on the total mass of the abrasive from the viewpoint that it is easy to obtain a polishing rate equal to the polishing rate of silicon nitride or a polishing rate lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. It is preferably in the following range. The content of the organic acid is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and particularly preferably 0.15% by mass or more. That is all. The content of the organic acid is preferably 10% by mass or less, more preferably 5.0% by mass or less, further preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less. It is extremely preferably 0.2% by mass or less. From these viewpoints, the content of the organic acid is preferably 0.01 to 10% by mass.

The content of the basic component is based on the total mass of the abrasive from the viewpoint that it is easy to obtain a polishing rate equal to the polishing rate of silicon nitride or a polishing rate lower than the polishing rate of silicon nitride as the polishing rate of silicon oxide. It is preferably in the following range. The content of the basic component is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, still more preferably 0.01% by mass or more, and particularly preferably 0.02% by mass. The above is extremely preferable, and it is 0.04% by mass or more. The content of the base component is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.15% by mass or less. From these viewpoints, the content of the base component is preferably 0.001 to 1.0% by mass.

The content of the pH adjuster (total content of organic acids, basic components, etc.) is preferably 5.0% by mass or less based on the total mass of the abrasive from the viewpoint of easily preventing aggregation of abrasive grains. It is more preferably 3.0% by mass or less, further preferably 1.25% by mass or less, particularly preferably 1.0% by mass or less, and extremely preferably 0.75% by mass or less. It is very preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less. The lower limit of the content of the pH adjuster is not particularly limited and may be, for example, 0% by mass.

(water)
The abrasive according to this embodiment contains water. As the water contained in the polishing agent, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water and the like can be used. In the present embodiment, water whose purity has been increased by operations such as removal of impurity ions by an ion exchange resin, removal of foreign substances by a filter, and distillation may be used.

(Abrasive pH)
The pH of the abrasive according to the present embodiment is preferably 6.0 from the viewpoint of easily polishing the surface to be polished containing cobalt at a stable polishing rate and from the viewpoint of easily suppressing corrosion of the surface to be polished containing cobalt. The above, more preferably 7.0 or more, further preferably 7.5 or more, particularly preferably 8.0 or more, extremely preferably 9.0 or more, and very preferably 10. It is 0 or more. The pH of the abrasive contains cobalt from the viewpoint of easily suppressing the dissolution of the surface to be polished containing a silicon compound (silicon oxide, silicon nitride, etc.) and the dissolution of abrasive grains (particularly, abrasive grains containing silica). From the viewpoint of stable polishing of the surface to be polished at a high polishing rate, it is preferably 12.0 or less, more preferably 11.5 or less, still more preferably 11.0 or less, and particularly preferably 10 or less. It is 5.5 or less, and extremely preferably 10.0 or less. From these viewpoints, the pH of the abrasive is preferably 6.0 to 12.0, more preferably 7.0 to 11.5, still more preferably 7.5 to 11.0, and in particular. It is preferably 8.0 to 10.5.

The pH of the abrasive can be measured with a pH meter (for example, Model F-51 manufactured by HORIBA, Ltd.). Specifically, standard buffers (phthalate pH buffer {pH: 4.01 (25 ° C)}, neutral phosphate pH buffer {pH: 6.86 (25 ° C)}, and hoe. After calibrating at 3 points using the acid salt pH buffer {pH: 9.18 (25 ° C.)}), the electrode was placed in an abrasive, and after 3 minutes or more had passed and stabilized, the value was measured and obtained. The measured value can be used as the pH of the polishing agent.

(Preservation method)
The abrasive according to the present embodiment may be stored as a one-component abrasive containing at least abrasive grains, amine A and water, and may be stored as a first liquid (slurry) containing abrasive grains and a second solution containing amine A. It may be stored as a two-component abrasive having the above solution (additional solution). In the two-component polishing agent, the slurry and the additive liquid are mixed, and the constituent components of the Ogai polishing agent are divided into the slurry and the additive liquid so as to obtain the polishing agent according to the present embodiment. The slurry contains, for example, at least abrasive grains and water. The additive liquid contains, for example, at least amine A and water. Additives other than amine A (oxidizing agent, metal corrosion inhibitor, pH adjuster, etc.) are preferably contained in the additive liquid among the slurry and the additive liquid. The constituent components of the abrasive may be divided into three or more liquids and stored.

In the two-component polishing agent, the slurry and the additive solution may be mixed immediately before or during polishing to prepare the polishing agent. The slurry and the additive liquid in the two-component polishing agent may be supplied onto the polishing surface plate, respectively, and the surface to be polished may be polished using the polishing agent obtained by mixing the slurry and the additive liquid on the polishing surface plate. ..

The abrasive according to this embodiment may be prepared as a storage liquid for an abrasive. The storage liquid for an abrasive is diluted with water to provide the abrasive according to the present embodiment. The storage liquid for abrasives is stored with the amount of water reduced from that at the time of use, and is diluted with water before or at the time of use. This makes it possible to reduce the cost, space, etc. required for transporting, storing, and the like of the abrasive. The storage liquid for polishing agent may be diluted with water immediately before polishing to prepare the polishing agent, or the storage liquid and water may be supplied on the polishing surface plate to prepare the polishing agent on the polishing surface plate. good. The dilution ratio of the storage liquid for abrasives is, for example, 1.5 times or more.

<Polishing method>
The polishing method according to the present embodiment includes a polishing step of polishing the surface to be polished using the polishing agent according to the present embodiment. The surface to be polished can contain silicon oxide and silicon nitride. In the polishing step, at least a part of the silicon oxide portion (the portion to be polished made of silicon oxide) and the silicon nitride portion (the portion to be polished made of silicon nitride) is polished and removed by using the polishing agent according to the present embodiment. be able to. According to such a polishing step, the surface to be polished containing silicon oxide and silicon nitride can be highly flattened. The polishing agent used in the polishing step may be the above-mentioned one-component polishing agent or an abrasive obtained by mixing the slurry of the above-mentioned two-component polishing agent with an additive solution.

The surface to be polished may contain cobalt. In the polishing step, at least a part of the cobalt-containing portion may be polished and removed by using the polishing agent according to the present embodiment, and the silicon oxide portion, the silicon nitride portion and the silicon nitride portion may be removed by using the polishing agent according to the present embodiment. At least a part of each of the cobalt-containing parts may be removed by polishing.

The surface to be polished may contain a metal material other than cobalt. In the polishing step, at least a part of the metal-containing portion (metal-polished portion; excluding the cobalt-containing portion) may be polished and removed by using the polishing agent according to the present embodiment, and the polishing agent according to the present embodiment may be removed. May be used to polish and remove at least a portion of each of the cobalt-containing portion and the metal-containing portion (excluding the cobalt-containing portion).

Metallic materials other than cobalt include copper (Cu), tungsten (W), molybdenum (Mo), manganese (Mn), tantalum (Ta), titanium (Ti), ruthenium (Ru), silver (Ag), and gold ( Au) and the like. As the metal-containing part, a copper-containing part (a part containing a single copper, a copper alloy, a copper oxide, an oxide of a copper alloy, etc.), a tungsten-containing part (a part containing a single tungsten, tungsten nitride, a tungsten alloy, etc.), Molybdenum-containing part (part containing molybdenum alone, molybdenum nitride, molybdenum alloy, etc.), manganese-containing part (part containing manganese alone, manganese nitride, manganese alloy, etc.), tantalum-containing part (tantal unit, tantalum nitride, tantalum alloy, etc.) (Containing part), titanium-containing part (part containing titanium alone, titanium nitride, titanium alloy, etc.), ruthenium-containing part (part containing ruthenium alone, ruthenium nitride, ruthenium alloy, etc.), noble metal (silver-containing part, gold-containing part, etc.) ) The content part and the like can be mentioned. The surface to be polished is a single metal of at least one selected from the group consisting of copper, tungsten, molybdenum, manganese, tantalum, titanium, ruthenium, silver and gold, and / or an alloy of the metal, a nitride of the metal, and the like. It may contain at least one selected from the group consisting of the oxide of the metal and the oxide of the alloy. In the polishing method according to the present embodiment, cobalt can be selectively polished even when such a surface to be polished is polished.

In the polishing step, a step of polishing the surface to be polished containing silicon oxide, a step of polishing the surface to be polished containing silicon nitride, a step of polishing the surface to be polished containing cobalt, and a step of polishing a surface to be polished containing a metal material other than cobalt. The steps of polishing the surface do not have to be clearly distinguished from each other, and when at least two of these steps are carried out simultaneously, the abrasives used in each step are the same. May also be different.

The polishing method according to the present embodiment is preferably performed by the CMP method. In the CMP method, while the polishing agent is supplied on the polishing pad (polishing cloth) of the polishing platen, the surface to be polished (surface) of the object to be polished is pressed against the polishing pad, and the polishing platen and the object to be polished are used. The surface to be polished is polished by relatively moving.

In the polishing method according to the present embodiment, the device used for polishing includes a holder for holding the object to be polished and a polishing surface plate connected to a motor or the like whose rotation speed can be changed and to which a polishing pad is attached. A general polishing device can be used. A motor or the like whose rotation speed can be changed may be attached to each of the holder and the polishing surface plate. As the polishing device, for example, a polishing device manufactured by Applied Materials: Reflection can be used. The polishing pad is not particularly limited, but a general non-woven fabric, polyurethane foam, a porous fluororesin, or the like can be used.

The polishing conditions of the polishing method according to this embodiment are not particularly limited. The rotation speed of the polishing surface plate is preferably 200 min ^-1 (200 rpm) or less so that the object to be polished does not jump out of the polishing surface plate. The pressing pressure of the object to be polished against the polishing pad is preferable from the viewpoint that it is easy to uniformly adjust the polishing rate (for example, the polishing rate of cobalt) in the surface to be polished and that sufficient flatness can be obtained after polishing. Is 1 to 100 kPa, more preferably 5 to 50 kPa.

During polishing, the abrasive can be continuously pumped between the polishing pad and the surface to be polished. There is no limit to the amount of abrasive supplied, but it is preferable that the surface of the abrasive pad is always covered with the abrasive.

The polishing method according to the present embodiment preferably includes a conditioning step for conditioning the polishing pad before each polishing step in order to perform polishing (CMP or the like) so that the surface state of the polishing pad is always the same. For example, a dresser with diamond particles can be used to condition the polishing pad with a liquid containing at least water.

The polishing method according to the present embodiment preferably includes a cleaning step of cleaning the object to be polished after polishing is completed. In the cleaning step, for example, the object to be polished after polishing can be thoroughly washed in running water, and then water droplets adhering to the object to be polished can be removed and then dried by using spin dry or the like.

The surface to be polished of the object to be polished in the present embodiment may contain silicon oxide, silicon nitride, cobalt, or a metal material other than cobalt. Examples of the object to be polished include a semiconductor substrate, a substrate such as a magnetic head, and the like.

A method of polishing the object to be polished 10 will be described in detail with reference to FIG. 1 as an example of the present embodiment. As shown in FIG. 1A, the object to be polished 10 includes a base portion 1, a plurality of silicon oxide portions 2, a plurality of silicon nitride portions 3, and a conductive substance portion 4, and a silicon oxide portion as an insulating material portion. 2 and a silicon nitride portion 3 are provided. The silicon oxide portion 2 and the silicon nitride portion 3 are, for example, linear, and a plurality of pattern portions composed of the silicon oxide portion 2 and the silicon nitride portion 3 adjacent to each other are formed on the base portion 1 apart from each other. The conductive substance portion 4 covers the base portion 1, the silicon oxide portion 2 of the pattern portion, and the silicon nitride portion 3 while filling the recesses between the pattern portions. The conductive substance portion 4 contains, for example, cobalt.

In one embodiment of the polishing method, first, as shown in FIG. 1 (b), the conductive substance portion 4 is polished and removed, and the silicon oxide portion 2 and the silicon nitride portion 3 of the pattern portion are exposed. 20 is obtained (first polishing step). Next, the silicon oxide portion 2, the silicon nitride portion 3, and the conductive substance portion 4 are polished and removed using the polishing agent according to the present embodiment, and the silicon oxide portion 2 is as shown in FIG. 1 (c). The surface composed of the silicon nitride portion 3 and the conductive material portion 4 is flattened to obtain the object to be polished 30 (second polishing step). As the polishing agent used in the first polishing step, it is preferable to use a polishing agent in which the polishing speed of the conductive material portion 4 is sufficiently high and the polishing speed of the silicon nitride portion 3 is low. The abrasive according to this embodiment may be used in both the first polishing step and the second polishing step.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples as long as it does not deviate from the technical idea of the present invention. For example, the composition of the abrasive, the polishing conditions, and the film to be polished may not be as described in this embodiment.

<Preparation of abrasive grains>
As abrasive grains, silica particles having an average secondary particle diameter of 60 nm (coloidal silica A), silica particles having an average secondary particle diameter of 65 nm (coloidal silica B), and silica particles having an average secondary particle diameter of 50 nm (coloidal). Silica C) was prepared. The average secondary particle size of the silica particles was measured by the photon correlation method using a light diffraction scattering type particle size distribution meter DELSA MAX PRO manufactured by BECKMAN COULTER. Specifically, the aqueous dispersion of silica particles is diluted with water so that the scattering intensity is 5.0 × 10 ⁴ to 1.0 × 10 ⁶ cps to obtain a measurement sample, and the measurement sample is placed in a plastic cell. And the average secondary particle size was measured.

<Preparation of evaluation board>
The following boards were prepared as the first to fourth evaluation boards.
First evaluation substrate: A substrate obtained by forming a cobalt film (thickness: 200 nm) made of cobalt (Co) on a silicon substrate (diameter 12 inch wafer).
Second evaluation substrate: A substrate obtained by forming a silicon oxide film (SiO ₂ film, thickness: 1000 nm) on a silicon substrate (wafer with a diameter of 12 inches).
Third evaluation substrate: A substrate obtained by forming a silicon nitride film (thickness: 200 nm) on a silicon substrate (diameter 12 inch wafer).
Fourth evaluation substrate: Wafer having SiO ₂ pattern and SiN pattern alternately arranged on a silicon substrate (wafer with a diameter of 12 inches) (SEMATECH 764).

<Preparation of abrasive>
The abrasives of Examples and Comparative Examples were prepared by mixing the components of Tables 1 to 3. Specifically, an amine, a metal anticorrosive agent and a pH adjuster were added to deionized water and then stirred to obtain a mixture (in Comparative Examples 1, 7 to 11 did not use amine). Abrasive particles were added to this mixture and stirred, and then hydrogen peroxide solution (30% by mass aqueous solution) was added as an oxidizing agent and mixed. Then, deionized water was added and mixed so that the content of each component was the content [unit: mass%] in Tables 1 to 3 to obtain the abrasives of Examples 1 to 18. The content of the abrasive grains in the table is the content of solid content, and the content of hydrogen peroxide (H ₂ O ₂ ) is the content of hydrogen peroxide itself.

<Measurement of pH>
The pH of each abrasive was measured according to the following. The results are shown in Tables 1 to 3.
・ Measurement temperature: 25 ° C
-Measuring instrument: pH meter ("Model F-51" manufactured by HORIBA, Ltd.)
-Measuring method: standard buffer (phthalate pH buffer {pH: 4.01 (25 ° C)}, neutral phosphate pH buffer {pH: 6.86 (25 ° C)}, and boric acid. After calibrating at 3 points using a salt pH buffer solution {pH: 9.18 (25 ° C.)}), the electrode was placed in an abrasive and the value after 3 minutes or more to stabilize was measured.

<Polishing of 1st to 3rd evaluation boards>
Each polishing agent is used to polish each film to be polished on the first to third evaluation substrates under the following polishing conditions, and the polishing rate of cobalt (Co-RR (Removal Rate)) and the polishing rate of silicon oxide (SiO). ₂ -RR) and the polishing rate of silicon nitride (SiN-RR) were measured. The difference in film thickness between the silicon oxide film and the silicon nitride film before and after polishing was determined using a light interferometry film thickness measuring device (manufactured by Filmometrics, trade name: F-80). The difference in film thickness before and after polishing the cobalt film is measured by measuring the electrical resistance value after polishing the cobalt film using a resistance measuring instrument VR-120 / 08S (manufactured by Hitachi Kokusai Denki Co., Ltd.), and polishing from the electrical resistance value. It was obtained by converting the film thickness before and after. The polishing rate (unit: nm / min) of each film to be polished was obtained by dividing the difference in film thickness by the polishing time. The results are shown in Tables 1 to 3.

[Polishing conditions]
-Grinding machine: Single-sided polishing machine (Applied Materials, Reflection LK)
・ Polishing pad: Fujibo Holdings, Inc., suede-like pad ・ Conditioning disc: A188 (3M)
・ Polishing pressure: 10.3kPa
・ Surface plate rotation speed: 98 rpm
・ Head rotation speed: 87 pm
・ Abrasive supply amount: 250 mL / min
・ Polishing time: 60 seconds

<Etching evaluation of substrate>
The chip is immersed in 100 mL of each polishing agent in a 100 mL beaker under the following conditions, the thickness difference of the cobalt layer before and after immersion is converted from the electric resistance value, and the etching rate of cobalt (Co-ER (Co-ER) is determined by the thickness difference and the immersion time. Etching Rate), corrosion rate, unit: nm / min) was calculated. The results are shown in Tables 1 to 3.
[Immersion conditions]
-Chip: A 20 mm x 20 mm chip obtained by cutting a silicon wafer (8 inch, blanket wafer) having a cobalt layer (thickness: 200 nm) formed on the surface.-Stirring speed: 200 rpm
・ Immersion time: 5 min

<Polishing of the 4th evaluation board>
In the fourth evaluation substrate, a linear SiN pattern (thickness: 1500 nm) is formed on a part of the silicon substrate, and then the silicon substrate on the portion without the SiN pattern is etched by 350 nm to form a linear recess. Next, it is a wafer obtained by forming a silicon oxide portion having a thickness of 600 nm on a SiN pattern and in a recess. The fourth evaluation substrate has a line width (L / S. Unit: μm) of SiN pattern (Line) and SiO ₂ pattern (Space) of 5/5, 10/10, 20/80, 25/25, 30 /. It has pattern regions of 70, 50/50 and 80/20.

The fourth evaluation substrate was polished with an abrasive containing calcined ceria particles having a particle diameter of 200 nm until the step of the silicon oxide portion disappeared. Then, it was polished with an abrasive containing nanoceria particles having a particle diameter of 3 nm until the SiN pattern was exposed, and then washed. After cleaning, polishing is performed for 30 seconds under the above-mentioned polishing conditions using the polishing agent of Example 15, and SiO ₂ in each pattern region is used with a light interference type film thickness measuring device (manufactured by Nanometrics, trade name: Nanospec AFT-5100). The thickness of the pattern and the SiN pattern was measured, and the step was measured by an AFM (atomic force microscope, manufactured by BRUKER, InSign CAP Compact Atomic Profiler). Then, it was further polished for 60 seconds with the abrasive of Example 15, and the thickness and the step were measured again by the same method. The respective polishing speeds were calculated based on the thicknesses and steps of the SiO ₂ pattern and SiN pattern before and after polishing for 60 seconds. The results are shown in Table 4.

According to the above measurement results, it can be seen that in Examples 1 to 18, the polishing rate of silicon oxide can be suppressed by using an abrasive containing an amine having a first acid dissociation constant pKa of 10.0 or more. Further, it can be seen that the polishing rate ratio (SiO ₂ / SiN) of silicon oxide to silicon nitride in Examples 1 to 18 is less than 2.0, which is smaller than that of Comparative Examples 1 to 11. In Examples 1, 4 and 10, the polishing rate ratio of silicon oxide to silicon nitride and the polishing rate ratio of silicon oxide to cobalt are both less than 1.0, and the polishing rate of silicon oxide is the polishing rate of silicon nitride. And it can be seen that the polishing rate of cobalt is lower than that of the polishing rate.

According to the comparison of Examples 1, 8 to 10, the comparison of Examples 6 and 7, and the comparison of Examples 11 to 14, the polishing rate of silicon oxide and the polishing rate of silicon nitride are determined according to the content of amine. , The polishing rate ratio of silicon oxide to silicon nitride can be adjusted, and when the amine content exceeds 0.20% by mass, it is easy to obtain the same polishing rate as the polishing rate of silicon oxide and the polishing rate of silicon nitride. At the same time, it can be seen that it is easy to obtain the same polishing speed as the polishing speed of silicon oxide and the polishing speed of cobalt. Further, according to the fifteenth embodiment, it can be seen that the polishing rate ratio of silicon oxide to silicon nitride can be adjusted to less than 1.0 in both the blanket wafer and the pattern wafer.

From the above results, the polishing rate of silicon oxide is the same as the polishing rate of silicon nitride or the polishing rate of silicon nitride by the polishing agent containing an amine having a first acid dissociation constant pKa of 10.0 or more. It was revealed that a smaller polishing rate was obtained.

1 ... base part, 2 ... silicon oxide part, 3 ... silicon nitride part, 4 ... conductive material part, 10, 20, 30 ... object to be polished.

Claims (18)

An abrasive containing abrasive grains, an amine having a first acid dissociation constant pKa of 10.0 or more, and water. The abrasive according to claim 1, wherein the amine contains an aliphatic amine. The abrasive according to claim 1 or 2, wherein the amine comprises a primary amine. One of claims 1 to 3, wherein the amine comprises at least one selected from the group consisting of t-amylamine, t-butylamine, isobutylamine, isoamylamine, diisobutylamine and 3-amino-1-propanol. The abrasive described. The abrasive according to any one of claims 1 to 4, wherein the amine content exceeds 0.20% by mass based on the total mass of the abrasive. The abrasive according to any one of claims 1 to 5, wherein the abrasive grains contain silica. The abrasive according to any one of claims 1 to 6, wherein the content of the abrasive grains is 0.01 to 20% by mass based on the total mass of the abrasive. The abrasive according to any one of claims 1 to 7, further containing an oxidizing agent. The abrasive according to any one of claims 1 to 8, further containing a metal corrosion inhibitor (excluding the amine). The abrasive according to any one of claims 1 to 9, further containing an organic acid. The abrasive according to any one of claims 1 to 10, further containing a base component (excluding the amine). The abrasive according to any one of claims 1 to 11, wherein the pH is 6.0 to 12.0. The polishing agent according to any one of claims 1 to 12, which is used for polishing a surface to be polished containing silicon oxide and silicon nitride. The polishing agent according to any one of claims 1 to 13, which is used for polishing a surface to be polished containing cobalt. A two-component polishing agent for obtaining the polishing agent according to any one of claims 1 to 14.
A two-component abrasive having a first liquid containing the abrasive grains and a second liquid containing the amine. The polishing agent according to any one of claims 1 to 14, or the polishing agent obtained by mixing the first liquid and the second liquid of the two-component polishing agent according to claim 15. A polishing method for polishing the surface to be polished using. The polishing method according to claim 16, wherein the surface to be polished contains silicon oxide and silicon nitride. The polishing method according to claim 16 or 17, wherein the surface to be polished contains cobalt.

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