JP2000311874A - Abrasive for semiconductor containing organic alkaline - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure sufficient polishing rate and excellent planarization capability by adding an organic alikaline compound and abrasive grains of a compound of at least one kind of elements selected from cerium, aluminum, germanium, zirconium, titanium, manganese and silicon. SOLUTION: The abrasive comprises a basic material, i.e., abrasive grains of an oxide, and an organic alikaline compound. The abrasive grains are a compound of at least one kind of elements selected from cerium, aluminum, germanium, zirconium, titanium, manganese and silicon. An organic alkaline compound is added along with the basic material, i.e., abrasive grains of an oxide, to the abrasive and the alkaline compound is preferably a quaternary ammonium salt group shown by a formula. In the formula, R1-R4 are any one of a 1-20C alkyl group, a 6-20C allyl group, or a 2-20C alkenyl group, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasive for chemical mechanical polishing in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art At present, various digital home appliances, mobile computers, portable information communication devices and the like are further miniaturized.
In response to demands for higher functionality, higher speed, and lower power consumption, semiconductor integrated circuits (hereinafter, simply referred to as semiconductor devices, LSI devices, semiconductor devices, and the like) used as key components in these devices. Investigations on miniaturization and high density are being continued, and a wiring pattern with a fine line width of submicron design rule is embedded on the insulating layer formed on the substrate, and the fine wiring structure is formed on the insulating layer. A multilayer wiring structure having a higher density and a higher density has been pursued.

As the miniaturization and density increase of the semiconductor device progress as described above, the unevenness on the surface of each layer becomes severe, and the unevenness exceeds the depth of focus of the lithography optical system.
In addition, since various problems such as disconnection and short-circuiting are caused in the multilayer wiring process, it is essential to flatten (preferably, completely planarize) the wafer surface at an appropriate stage of the manufacturing process. .

[0004] Therefore, as an important key technology of the flattening process, in a manufacturing process of a semiconductor device having a multilayer wiring structure, an insulating film and / or a metal film formed on each layer (on a semiconductor substrate) of the semiconductor device are super-precisely formed. Chemical Mechanical Polishing (Chemical Mec)
hanical Polishing; may be hereinafter referred to as CMP. ) Has been noticed.

Conventionally, aluminum (Al) -based wiring materials are often used because they can be easily patterned by dry etching or the like. In the case of Al-based wiring,
Under the design rule of a wiring width of 0.25 μm or less, wiring resistance between elements cannot be ignored and a large wiring delay time occurs. Also, with this, Al
There is a problem that power loss due to charging and discharging due to parasitic capacitance between system wirings becomes a major obstacle to reducing power consumption of mobile devices and the like.

For this reason, copper (C), which is a lower-resistance material, is used.
u) Wiring and Cu alloy wiring (hereinafter abbreviated as Cu etc.)
Attempts have been made to use this as a multilayer wiring structure for next-generation LSI devices. For Cu and the like, the dry etching temperature is high, and it is not possible to pattern a thin film by dry etching as easily as Al. Therefore, usually, electrolytic plating is performed on wiring grooves and / or via holes (contact grooves) on an interlayer insulating film. Cu or the like is buried by such means as above, and this is polished by CMP to planarize excess Cu or the like.

[0007]

However, unlike Al, when Cu or the like is used, a stable passive oxide film is not formed and Si is used.
Because and SiO ₂ easily diffused into the interlayer insulating film formed by, for preventing diffusion of Cu between the insulating film and the Cu wiring, Ta, TaN, Ti, TiN, WN, refractory metal like or The nitride film or the like is used as a barrier metal layer on the inner walls and bottoms of the wiring grooves and via holes. This thickness is several tens nm on a flat surface, and several nm on an inner wall of a wiring groove or a via hole. Among such barrier metals, in particular, Ta and TaN
Has attracted the most attention because it has features of high barrier properties, easy thinning, and high adhesion to insulating films and Cu wiring.

As described above, in the next-generation semiconductor process, the Cu-based wiring technology and the C
MP is required. At present, as an abrasive, an abrasive slurry containing alumina or the like as abrasive grains and H ₂ O ₂ or the like as an oxidant is used, and an oxidized product oxidized while grinding the surface to be polished with the abrasive grains is used as a polishing pad ( Attempts have been made to remove them with a polishing means such as a polishing cloth) and an abrasive slurry. However, according to what we have studied, although Cu and the like can be polished relatively easily, among the barrier metal layers,
In particular, Ta and TaN are mechanically harder than Cu and insulating films and have poor chemical reactivity, so that a sufficient polishing rate cannot be obtained, and only the Cu wiring portion is cut into a concave shape during polishing. It has been found that there is a problem that a phenomenon called dishing occurs, and it is difficult to perform planarization polishing by CMP until the surface of the interlayer insulating film is exposed. for that reason,
There is a need for an excellent abrasive that can easily polish a barrier metal layer such as Ta or TaN together with Cu.

An object of the present invention is to provide an abrasive having a sufficient polishing rate for chemical mechanical polishing in a semiconductor device manufacturing process having a metal wiring layer and its barrier layer. In particular, when the metal wiring layer is made of Cu or the like and the barrier layer is made of Ta or TaN, Cu
An object of the present invention is to provide a polishing agent which can prevent dishing of a Cu wiring portion and has excellent flattening ability by polishing the barrier layer when polished at the same time as wiring with a high polishing force.

[0010]

Means for Solving the Problems (1) According to the present invention,
An abrasive for chemical mechanical polishing containing an abrasive containing an oxide of at least one element of cerium, aluminum, germanium, zirconium, titanium, manganese or silicon and an organic alkali compound, formed on a semiconductor substrate A polishing agent containing an organic alkali compound for polishing a semiconductor device having the metal wiring layer and the barrier layer formed thereon.

(2) Further, according to the present invention, the polishing agent is carried on a polishing means, and at least a part of a semiconductor device having a metal wiring layer and a barrier layer on the substrate is polished. And a method of polishing a semiconductor substrate. Still other embodiments of the present invention will be apparent from the following description.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The metal wiring layer to be polished in the present invention is not particularly limited, but Cu, W, Al, Ti or the like or an alloy thereof is used. In particular, Cu or an alloy thereof is preferably used as a metal having high utility when polished simultaneously with the barrier film in the abrasive of the present invention.

The barrier film is preferably made of tantalum (Ta), a tantalum alloy or a compound thereof from the viewpoint of the adhesion to the insulating film and the Cu wiring and the performance of preventing the electromigration of Cu. As a tantalum alloy, Ta and A
Alloys with l, Ti, Si, W, Mo, Zn or the like are mentioned as preferred ones. Further, as the tantalum compound, nitride (TaN), oxide (TaOx), oxynitride (TaOyNz) [where x, y, and z are arbitrary numerical values. ] Are preferred. The tantalum compound includes the above-described compound of the Ta alloy.

The polishing agent of the present invention comprises abrasive grains composed of an oxide serving as a base material and an organic alkali compound.

The abrasive grains of the present invention are cerium, aluminum
, Germanium, zirconium, titanium, manganese or
Is an oxide of at least one element of silicon
You. For example, specifically, cerium oxide (ceria, Ce)
O_Two ), Aluminum oxide (alumina, Al_Two O_Three ),
Germanium oxide (Germania, GeO, GeO_Two ),
Zirconium oxide (zirconia_,ZrO_Two ), Titania
(Titania_,TiO_Two ), Manganese oxide (MnO_Two ,
Mn_Two O_Three , Mn_Three O_Four Etc.) and silicon dioxide (silicone)
Mosquito, SiO_Two ) Is at least one selected from
In particular, ceria, al
Mina, silica, zirconia, titania, germania, two
Manganese oxide is preferred and contains ceria or ceria
Mixtures are most preferred. In addition, as a compound of silicon,
Not only oxides but also silicon nitride (Si_Three N _Four Use
It is also possible.

These may be used alone or in combination of two or more. The weight average particle diameter of these abrasive grains, considering the polishing rate and the amount of scratches generated,
0.003 to 5.0 μm is preferable, and 0.01 to 0.5 μm is preferable.
μm is more preferred. If the particle size is smaller than this, the polishing force decreases, and if it is larger than this, the possibility of scratching increases.

The weight average particle diameter is a particle diameter at which the particle size distribution is determined on a mass basis and the cumulative curve is 50% in a cumulative curve in which the total mass is 100%. This is also referred to as a 50% diameter based on mass (see, for example, Chemical Engineering Handbook “Revised 5th Edition” (edited by the Society of Chemical Engineers), pp. 220-221). The particle size is measured by sufficiently dispersing in a medium such as water by ultrasonic treatment or the like and measuring the particle size distribution.

In the present invention, the abrasive contains an organic alkali compound together with the abrasive grains composed of an oxide serving as a base material, and the organic alkali compound is represented by the formula (1) or (2). Is preferably a quaternary ammonium base represented by

[0019]

Embedded image (In the formula, R ^{1 to} R ⁴ each independently represent an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms.)

The alkyl group having 1 to 20 carbon atoms includes methyl, ethyl, n-propyl, i-propyl and n-propyl.
-Butyl, i-butyl, s-butyl, t-butyl, n-
Pentyl, i-pentyl, neopentyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl (
Cetyl), heptadecyl, octadecyl, nonadecyl,
Linear hydrocarbon groups such as eicosyl; and alicyclic hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, 1-cyclohexenyl, cyclooctyl and the like.

The aryl group having 6 to 20 carbon atoms includes phenyl, o-tolyl, m-tolyl, p-tolyl,
Xylyl, mesityl, o-cumenyl, m-cumenyl, p
-Cumenyl, benzyl, methylbenzyl, phenicyl,
And aromatic hydrocarbon groups such as biphenyl, naphthyl, anthryl, and phenanthryl. Examples of the alkenyl group having 2 to 20 carbon atoms include vinyl, 1-propenyl, allyl, i-propenyl, 1-butynyl, 2-butynyl,
-Pentynyl, 1,3-butadienyl, 3-methyl-2
-Unsaturated hydrocarbon groups such as butenyl.

Since R ^{1 to} R ⁴ are each independently selected, all of R ^{1 to} R ⁴ may be the same or different.

Specific examples of such a quaternary ammonium base include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra (n-propyl) ammonium hydroxide and tetra (i-propyl) hydroxide.
Ammonium, tetra (n-butyl) ammonium hydroxide, tetra (n-pentyl) ammonium hydroxide, tetraneopentylammonium hydroxide, tetraheptylammonium hydroxide, tetraoctylammonium hydroxide, trimethylethylammonium hydroxide, dimethylhydroxide Diethylammonium, trimethylpropylammonium hydroxide, triethylmethylammonium hydroxide,
Tri (n-propyl) methylammonium hydroxide hydroxide, tri (i-propyl) methylammonium hydroxide,
Tri (n-butyl) methylammonium hydroxide, tri (n-pentyl) methylammonium hydroxide, trineopentylmethylammonium hydroxide, trimethylcyclopropylammonium hydroxide, triethylcyclopropylammonium hydroxide, tri (n-butylammonium hydroxide) Propyl) cyclopropylammonium, tri (i-propyl) hydroxide
Cyclopropylammonium, tri (n-butyl) cyclopropylammonium hydroxide, tri (n-pentyl) cyclopropylammonium hydroxide, trineopentylcyclopropylammonium hydroxide;

Trimethylphenylammonium hydroxide,
Triethylphenylammonium hydroxide, tri (n-propyl) phenylammonium hydroxide, tri (i-propyl) phenylammonium hydroxide, tri (n-butyl) phenylammonium hydroxide, tri (n-butyl) phenylammonium hydroxide
-Pentyl) phenylammonium, trimethylbenzylammonium hydroxide, triethylbenzylammonium hydroxide, tri (n-propyl) benzylammonium hydroxide, tri (i-propyl) benzylammonium hydroxide, tri (n-butyl) benzylammonium hydroxide , Tri (n-pentyl) benzylammonium hydroxide, dimethylcetylphenylammonium hydroxide, diethylcetylphenylammonium hydroxide,
-Propyl) cetylphenylammonium, di (i-propyl) cetylphenylammonium hydroxide, di (n-butyl) cetylphenylammonium hydroxide, di (n-pentyl) cetylphenylammonium hydroxide, dimethylcetylbenzylammonium hydroxide, Diethylcetylbenzylammonium hydroxide, di (n-propyl) cetylbenzylammonium hydroxide, di (i-propyl) cetylbenzylammonium hydroxide, di (n-butyl) cetylbenzylammonium hydroxide, di (n-pentyl hydroxide) ) Cetylbenzylammonium;

Trimethylvinylammonium hydroxide, triethylvinylammonium hydroxide, tri (n-
Propyl) vinylammonium, tri (i-propyl) vinylammonium hydroxide, tri (n-butyl) hydroxide
Vinylammonium, tri (n-pentyl) vinylammonium hydroxide, trineopentylammonium hydroxide and the like.

Among them, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra (n-propyl) ammonium hydroxide, Particularly preferred are tetra (i-propyl) ammonium hydroxide, tetra (n-butyl) ammonium hydroxide, tetra (i-butyl) ammonium hydroxide, tetra (n-pentyl) ammonium hydroxide and tetraneopentylammonium hydroxide.

These quaternary ammonium bases used in the present invention are different from ordinary amines in that they do not decompose even when the aqueous solution is concentrated, can have an extremely high OH ^- concentration, and have the equivalent of KOH and NaOH. (PKb:
It shows strong basicity of about 0).

The quaternary ammonium base used in the present invention can be easily synthesized by reacting a quaternary ammonium salt obtained by reacting a corresponding tertiary amine with an alkyl halide with silver hydroxide such as KOH. can do.
The quaternary ammonium base formed can be separated as crystals from the filtrate. Moreover, it can be easily obtained as a commercial product.

The method of using the abrasive of the present invention is not particularly limited, but the above-mentioned abrasive grains are sufficiently dispersed in water such as ion-exchanged water with a stirring mixer or a homogenizer, and the solid content is 0.1 to 30% by weight. Preferably, it is used as a slurry of 1 to 15% by weight (hereinafter also referred to as an abrasive slurry). In addition, a dispersing agent, a thickening agent, an oxidizing agent, a surfactant, an antifoaming agent, a pH adjusting agent, or the like may be appropriately added to the slurry and used.

As the oxidizing agent, a known oxidizing agent may be used, and hydrogen peroxide, urea peroxide, peracetic acid, iron nitrate, iodate and the like can be used.

The organic alkali compound such as a quaternary ammonium base of the present invention is usually used by dissolving in the abrasive slurry. This concentration is 0.0
It is from 0.01 to 30% by weight, preferably from 0.01 to 20% by weight.

If the amount of the organic alkali compound is smaller or larger than this, the polishing power of the abrasive of the present invention on the metal layer or metal compound layer is undesirably reduced.

Since the polishing agent of the present invention does not contain an alkali metal such as NaOH or KOH which has been conventionally added for improving the polishing rate, the alkali metal is diffused into the insulating film and the semiconductor device is removed. Without reducing the reliability.

In the present invention, the oxide abrasive grains such as ceria as the base material can be easily obtained by firing a raw material such as rare earth carbonate in an electric furnace, and the particle size of the raw material is adjusted by grinding or the like. Thus, the particle size of the product can be controlled to a desired range.
After firing, it is also possible to selectively obtain particles having a preferred particle size by classification or the like.

Polishing using this abrasive slurry can be carried out according to a conventional method. For example, a polishing head provided with a driving device for rotating while holding a material to be polished such as a semiconductor substrate on an upper portion, and a rotatable platen to which a lower polishing pad (polishing cloth) opposed thereto is attached
In the CMP apparatus comprising (platen), the polishing means such as the polishing cloth carries the polishing slurry of the present invention, that is, while the polishing slurry is supplied on the polishing cloth, the semiconductor substrate is flattened. Should be performed.

[0036]

The polishing slurry of the present invention contains a strongly basic organic alkali compound such as a quaternary ammonium base in the polishing slurry together with abrasive grains made of an oxide such as ceria. When applied to polishing of a device having a formed metal wiring layer such as Cu and its barrier layer,
It is considered that oxidation of the metal layer to its oxide or ions is greatly promoted.

In addition, since these organic alkali compounds easily react with chemically stable Ta or TaN which is a barrier layer of the metal layer, the polishing rate can be greatly increased. Therefore, it is considered that dishing due to selective polishing of only the Cu wiring can be prevented. The organic alkali compound exerts its effect particularly when it is mixed with abrasive grains composed of an oxide serving as a base material.

[0038]

EXAMPLES The present invention will be described in more detail with reference to the following examples, which are merely examples, and the technical scope of the present invention is not limited to these examples.

First, the abrasive slurries of Examples 1 to 12 were prepared by the following method, and the semiconductor substrate prepared by the method described later was subjected to chemical mechanical polishing. The polishing rate and flatness during polishing were measured by the following methods, and the results are shown in Table 1.
Here, Examples 1 to 11 are working examples, and Example 12 is a comparative example.

(1) Preparation of abrasive [Example 1] 3% by weight of cerium oxide (trade name: SHS110 (weight average particle size: 0.2 μm), manufactured by Seimi Chemical Co., Ltd.) based on ion-exchanged water, and water 0.2% of tetramethylammonium oxide (TMAH) (manufactured by Tokyo Chemical Industry Co., Ltd.)
An abrasive slurry to which weight% was added was prepared.

Example 2 Instead of TMAH, tetraethylammonium hydroxide (TEAH) (Tokyo Chemical Industry Co., Ltd.)
Abrasive slurry was prepared in the same manner as in Example 1 including the concentration, except that the slurry was used.

Example 3 2% by weight of cerium oxide (same as above) based on ion-exchanged water, alumina (manufactured by Seimi Chemical Co., Ltd .: trade name: ALS100 (weight average particle size: 0.2 μm)
m)) in an amount of 1% by weight and tetra (n-butyl) ammonium hydroxide (TBAH) (manufactured by Tokyo Chemical Industry Co., Ltd.) in an amount of 0.2%.
An abrasive slurry to which weight% was added was prepared.

[Example 4] Abrasive slurry was prepared in the same manner as in Example 3, including the concentration, except that tetra (n-propyl) ammonium hydroxide (TPAH) (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of TBAH. Was adjusted.

Example 5 2% by weight of cerium oxide (same as above) based on ion-exchanged water, zirconia (Kanto Chemical Co., Ltd.)
Manufacture: 1% by weight of a zirconium oxychloride octahydrate hydrolyzed (weight average particle size: 0.1 μm) and 0.1% of phenyltrimethylammonium hydroxide (PhMAH) (manufactured by Tokyo Chemical Industry Co., Ltd.). An abrasive slurry to which 2% by weight was added was prepared.

Example 6 2% by weight of cerium oxide (same as above) with respect to ion-exchanged water, titanium oxide (trade name: P25, manufactured by Nippon Aerosil Co., Ltd .; weight average particle diameter: 0.05 μm)
m)) and 0.2% by weight of benzyl cetyl dimethyl ammonium hydroxide (BSMAH) (manufactured by Tokyo Chemical Industry Co., Ltd.) were prepared.

Example 7 2% by weight of cerium oxide (same as above) based on ion-exchanged water, manganese dioxide (manufactured by Seimi Chemical Co., Ltd., trade name: MNS100 (weight average particle diameter: 0.1%))
1% by weight of benzyl cetyl dimethyl ammonium hydroxide (BSMAH) (manufactured by Tokyo Chemical Industry Co., Ltd.)
Was added to prepare an abrasive slurry to which 0.2% by weight was added.

Example 8 3% by weight of alumina (manufactured by Seimi Chemical Co., Ltd., trade name: ALS100 (weight average particle size: 0.2 μm)) in ion-exchanged water, tetraethylammonium hydroxide (TEAH) (Tokyo, Japan) Chemical Industry Co., Ltd.)
Was added to prepare an abrasive slurry to which 0.2% by weight was added.

Example 9 An abrasive slurry was prepared in the same manner as in Example 1 including the concentration, except that TMAH (same as above) was used instead of TEAH.

Example 10 Silica obtained by hydrolyzing tetraisopropoxide silane with ion-exchanged water (manufactured by Kanto Chemical Co., Ltd .: (weight average particle size: 0.1 μm)
m)) and 3% by weight of TMAH (same as above) were added to prepare an abrasive slurry.

[Example 11] TPAH instead of TMAH
An abrasive slurry was prepared in the same manner as in Example 10 except for using (same as above), including the concentration.

[Example 12] Polishing was performed in the same manner as in Example 1 except that TMAH was not added, including the concentration.

(2) [Preparation of Semiconductor Substrate and Polishing Test] As shown in FIG. 1A, a 500 nm SiO ₂ insulating film 2 was formed on a Si substrate 1 by CVD of TEOS.
Next, as shown in FIG. 1B, a wiring groove 5 was patterned in the SiO ₂ insulating film 2 by RIE. afterwards,
As shown in FIG. 1C, a Ta barrier film 3 was formed to a thickness of 50 nm by RF sputtering. The sputtering pressure was set at 2 Torr.

Further, as shown in FIG. 1D, a Cu film 4 was formed as a blanket film to a thickness of 500 nm on the surface by DC sputtering.

From now on, as shown in FIG.
The buried wiring 6 made of Cu was formed by flattening by the P method except for Cu in portions other than the grooves. The abrasive slurries of Examples 1 to 12 were used as abrasives by the CMP method. The polishing conditions are as follows.

Polishing machine: Single-side polishing machine (platen diameter: 550 mm) Platen (platen) Number of revolutions: 100 rpm Platen material: Stainless steel Processing pressure: 30 kPa Polishing cloth: Nonwoven fabric type polishing pad Polishing slurry: Automatic supply on the platen

Under these conditions, polishing was performed until the Ta barrier layer 3 was removed by polishing and the state shown in FIG. 1E was obtained, and the flatness and polishing rate were measured under the following conditions.

[Flatness] The Cu wiring layer shown in FIG. 1E was observed by a cross-sectional SEM photograph and evaluated in the dishing state. A is the case without dishing, B is the case where the dishing is slight but improved compared to the conventional one (equivalent to Example 12), and C is the case where the dishing is large.

[Polishing Rate] The amount of grinding on the surface was measured, and the amount of polishing per minute was indicated as the polishing rate (Å / min). Table 1 shows the results.

[0059]

[Table 1]

[0060]

As is clear from the above examples, by using the abrasive of the present invention, high flatness and high polishing rate can be obtained in a semiconductor manufacturing process using Ta and a Ta compound for the barrier layer of the metal wiring layer. It can be seen that high-precision chemical-mechanical polishing combining with the above becomes possible. That is, by using the polishing agent of the present invention, a semiconductor device that satisfies the demands for high speed and miniaturization can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of a semiconductor substrate in an example of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Si substrate 2 SiO ₂ insulating film 3 barrier film 4 Cu film 5 wiring groove 6 embedded wiring

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuo Sunahara 3-2-1-10 Chigasaki, Chigasaki City, Kanagawa Prefecture Inside Seimi Chemical Co., Ltd. (72) Inventor Satoshi Takemiya 1150 Hazawacho, Kanagawa-ku, Yokohama-shi, Kanagawa-ken (72) Inventor Yasuhiro Sanada 1150 Hazawacho, Kanagawa-ku, Yokohama-shi, Kanagawa-ken Asahi Glass Co., Ltd.

Claims (6)

[Claims] An abrasive for chemical mechanical polishing containing an abrasive comprising an oxide of at least one element of cerium, aluminum, germanium, zirconium, titanium, manganese or silicon and an organic alkali compound, An abrasive containing an organic alkali compound for polishing a semiconductor device having a metal wiring layer and a barrier layer formed on a semiconductor substrate. 2. The organic alkali compound is a quaternary ammonium base represented by the formula (1) or [1].
The abrasive according to the above. Embedded image (In the formula, R ^{1 to} R ⁴ each independently represent an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms.) 3. The quaternary ammonium base is tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra (n-propyl) ammonium hydroxide, tetra (i-propyl) ammonium hydroxide, tetra (n-butyl) hydroxide. 3.) The abrasive according to claim 2, wherein the abrasive is at least one selected from ammonium, tetra (i-butyl) ammonium hydroxide, tetra (n-pentyl) ammonium hydroxide and tetraneopentylammonium hydroxide. 4. The polishing agent according to claim 1, wherein the metal wiring layer is made of copper (Cu) or a copper alloy. 5. The abrasive according to claim 1, wherein the barrier layer is tantalum or a tantalum compound (including a tantalum alloy and a tantalum alloy compound). 6. A polishing apparatus comprising the polishing agent according to claim 1, wherein at least a part of a semiconductor device having a metal wiring layer and a barrier layer on a substrate is polished. Polishing method for a semiconductor substrate.