JP2002270548A - Slurry for polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide new slurry for polishing that has one's own oxidation force in a polishing abrasive, and has polishing characteristics also to Cu. SOLUTION: The slurry for polishing should contain a spinel type manganese oxide that includes a different kind of metal M in an 8A site and is shown by a general expression M1- XMn2 O4 (0<X<=1). The slurry for polishing should extract the different kind of metal M of the 8A site by acid treatment, and be mentioned in claims 1 to 3. The slurry for polishing should have a pH of 3.0 or less and 0.1 or more, and be mentioned in claims 1 to 4. Additionally, the slurry for polishing should be used for polishing the wiring material of a semiconductor integrated circuit for flattening, and be mentioned in the claims 1 to 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polishing slurry used as an abrasive, and more particularly, to a polishing slurry used in a planarization process by a chemical mechanical polishing technique in a wiring process of a semiconductor integrated circuit. Things.

[0002]

2. Description of the Related Art In recent years, with the rapid progress of information technology, there has been a trend to increase the speed by miniaturization, higher density, and higher integration of large-scale integrated circuits (LSI, ULSI, VLSI). Technology development is being carried out by increasing the number of layers. In order to achieve multi-layered wiring, it is necessary to reduce the wiring pitch width and the capacitance between wirings. As a solution for reducing the wiring pitch width, tungsten and aluminum, which are existing metal wiring materials, are made more resistivity-resistant. Low copper (Cu)
The technology development to change to has been energetically studied.

[0003] It is considered difficult to form Cu wiring by dry etching due to the vapor pressure of a product. Therefore, a damascene process by embedding tends to be the mainstream. Further, when the wiring material is made of Cu, the diffusion speed of the wafer material into silicon (Si) and the thermal oxide film (SiO ₂ ) becomes extremely high, which affects the transistor function, thereby interposing a barrier metal that prevents diffusion. The structure is applied.

[0004] Multi-layering of wiring consists in flattening the wiring pattern of each layer and the wiring layer with high precision, and flattening of the wiring buried by the damascene method utilizes the synergistic effect of mechanical polishing action and chemical polishing action. So-called CMP (Chemica)
1 Mechanical Polishing), and the Cu wiring material is polished by the same method.

[0005] Cu is a noble metal and easily forms an oxide and becomes passivated in the presence of oxygen. For elution of Cu, oxidizing power stronger than hydrogen ions is required, and usually elution is achieved by adding an oxidizing agent. Further, it is formed by adding a chloride or a nitrogen compound such as ammonia which forms a complex ion.

As described above, C for the purpose of polishing Cu
The presence of an oxidizing agent is indispensable for the CMP agent for u. However, the oxidizing agent to be converted into a solution causes a change with time such as decomposition and deterioration, and it is difficult to obtain sufficiently satisfactory characteristics while leaving a problem in stability during polishing and storage. Therefore, it is desired to develop abrasives having an oxidizing power or abrasives having an oxidizing power.

Japanese Patent Application Laid-Open Nos. 9-22887 and 9-22888 disclose an abrasive using MnO2 as an abrasive having an oxidizing power to the abrasive grains. However, as a result of investigations by the present inventors, it has been confirmed that the polishing rate is not sufficient with the polishing slurry composition in these proposals, and in particular, polishing characteristics for Cu are not recognized.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems of the prior art, and has a novel property in which abrasive grains have a self-oxidizing power and also have a polishing property on Cu. It is intended to provide a suitable polishing slurry.

[0009]

Means for Solving the Problems The present inventors have found that a spinel-type manganese oxide is used as a positive electrode material of a lithium secondary battery which is a 4V class battery, and that the electromotive force is a charged state, that is, Focusing on the fact that it increases with the undoping of the metal occupied by the A-site, the present inventors have conducted intensive studies, and as a result, have found that spinel-type manganese oxide can be applied as a polishing agent, leading to the present invention.

That is, the present invention resides in a polishing slurry containing a manganese oxide represented by the general formula M _1-x Mn ₂ O ₄ (0 <X ≦ 1) containing a dissimilar metal M at the 8A site as an abrasive. , The pH of the slurry containing the abrasive is 3.0 or less,
By setting the value to 0.1 or more, particularly, when the wiring material is C
This is a polishing slurry suitable as a CMP slurry for planarizing a semiconductor device made of u by polishing.

The present invention will be described in more detail.

The abrasive used in the present invention has a general formula M _1-x Mn ₂ O ₄ (0 <X ≦
A spinel-type manganese oxide represented by 1),
The material from which the dissimilar metal M at the site is completely extracted is disclosed in
It is a substance belonging to λ-MnO ₂ which is a novel MnO ₂ described in JP-A-5-100224.

The dissimilar metal M at the 8A site according to the present invention is composed of a metal having a lower standard monopolar potential (E ⁰ ) than manganese.

The standard monopolar potential (E ⁰ ) corresponds to the electromotive force of a battery when combined with a standard hydrogen electrode at the same temperature.

In the case of a metal having a standard monopolar potential (E ⁰ ) which is nobler than manganese, there is a problem in dedoping a different metal.

In addition, the dissimilar metal M at the 8A site of the present invention is particularly preferably Li, Zn or Mg because of the ease of extraction.

The undoping of the dissimilar metal of the present invention can be performed by an acid treatment.

The type of the acid is not particularly limited, and mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, and organic acids can be used. Further, in some cases, it can be performed by an oxidation treatment, for example, an oxidizing agent treatment such as ammonium persulfate, or an electrochemical oxidation treatment. P of the polishing slurry of the present invention
H is desirably 3.0 or less, preferably 0.1 or more, and more preferably 2.0 or less.

When the pH is 3.0 or more, the abrasiveness of the slurry is not exhibited or the polishing rate becomes extremely low.

On the other hand, when the pH is 0.1 or less, the basic effect as an abrasive is not hindered, but there is a possibility that workability and maintenance and management of equipment materials may be problematic. .

The pH adjuster is not particularly limited, and inorganic acids and organic acids may be used, but it is usually preferable to use an inorganic acid.

Although the particle size of the abrasive is not limited, it is preferable that the particle size is fine in consideration of the influence on the surface of the wiring material such as scratch, and the average particle size (D ₅₀ ) is obtained by pulverization using a dry method or a wet method. It is preferable that the thickness be 1.0 μm or less.

The concentration of the polishing agent can be applied in any range from a low concentration to a high concentration, but it is preferable to use the polishing agent at a concentration as low as possible from the viewpoint of economy and slurry processing load. It enables polishing at a concentration.

The polishing slurry of the present invention is particularly suitable when the wiring material of the semiconductor integrated circuit is composed of Cu.

The Cu wiring is usually formed by sputtering, CVD, plating or the like.

When polishing the Cu wiring material using the polishing slurry of the present invention, if the pH of the slurry is 3.0 or more, the Cu surface is not processed or becomes extremely low even if processed. On the other hand, when the pH of the slurry is 3.0 or less, polishing characteristics appear, and the polishing characteristics improve as the pH decreases.

The general formula of the present invention, M _{1 -X} Mn ₂ O ₄ (0 <X
The manganese oxide represented by ≦ 1) is not only a newly synthesized oxide, but also used as a cathode material of a secondary battery and deteriorated.
It is sufficiently possible to use the recycled cathode material of the collected waste battery.

The polishing slurry of the present invention can be used in combination with another manganese oxide.

The polishing slurry of the present invention can be applied not only to a pure system composed of only an abrasive but also to a dispersant and a chelating agent which are generally used as an additive of a CMP slurry. As long as the conditions do not deviate from the pH range of the slurry, no problem occurs, and in some cases, the polishing characteristics of the present invention can be suitably achieved.

Further, since the abrasive used in the present invention is manganese oxide, a general technique (Chemical Dictionary 3,
p941, Kyoritsu Shuppan Co., Ltd., first edition of S39.9.30) in the presence of a dilute acid,
For example, since it can be easily dissolved by a mixed solution with a reducing agent such as H ₂ O ₂ , it has an advantage that it is suitable for cleaning after polishing.

[0031]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 The Li / Mn molar ratio of lithium carbonate and manganese dioxide was
1: 2, mix in a mortar, and place this mixture in a crucible
Using a normal electric furnace, set the temperature to 200 ° C / hr.
Fired at 800 ° C for 24 hours in air
Pinel (LiMn _TwoO_Four) Was synthesized. This LiMn
_TwoO_Four, 150 g in a beaker and pure water, 4000 ml
And stirred, and concentrated sulfuric acid diluted 1: 1 with pure water
The pH was adjusted to about 2.0 by dropwise addition. Over time
Repeated pH adjustment by dropping sulfuric acid because pH rises
Check that the pH does not fluctuate from about 2.0, and wash with pure water.
After cleaning, drying was performed.

When the composition analysis of the obtained powder was measured by an atomic absorption method, the composition was Li _0.07 Mn ₂ O ₄ and the oxidation degree of Mn was +4.0.

X-ray diffraction of the powder after Li removal showed a diffraction pattern belonging to λ-MnO ₂ of spinel type MnO ₂ as shown in FIG.

The Li-free material is pulverized by a wet method to obtain a powder having an average particle diameter (D ₅₀ ) of 1 μm. To adjust the pH of the slurry to 12.0.
To 0.5.

Next, the 15 m of the Cu-plated wafer is
An m-square dicing product was used as a sample, mounted on a work plate 1 shown in FIG.

Polishing was performed while the previously adjusted slurry was supplied from the slurry supply nozzle 4 of FIG. 1 at a dropping rate of 20 ml / min while the rotation speed of the platen 3 of FIG. 1 was 30 rpm.

The load amount was 250 g / cm ² , and the pad used was IC1000 / SUBA400 manufactured by Rodale Nitta.

FIG. 3 shows the results of the processing speed in the sheet resistance measurement using the four terminals. When the pH is 3.0 or more, no polishing characteristics are observed. On the other hand, by setting the pH of the slurry to 3.0, polishing characteristics began to appear, and the polishing rate increased with a decrease in the pH of the slurry.

EXAMPLE 2 Potassium hydroxide was added to a mixed aqueous solution having a molar ratio of Zn / Mn of 1: 2 using manganese nitrate and zinc nitrate.
₂ O ₄ was synthesized. This ZnMn ₂ O ₄ was heat-treated in the same manner as in Example 1, and Zn was extracted in the same manner as in Example 1 except that hydrochloric acid was used.

[0041] The X-ray diffraction pattern of the resulting powder as in Example 1, showed a pattern attributable to the λ-MnO _2. Also,
As a result of composition analysis by atomic absorption, the composition became Zn _0.3 Mn ₂ O _{4 and} the degree of oxidation of Mn was +3.86.

The de-Zn powder was pulverized and polished under the same conditions and the same evaluation method as in Example 1. However, the pH of the slurry was from 5.0 to 1.0.

As compared with Example 1, the polishing rate showed a somewhat lower value as a whole, but the processing behavior with respect to pH was similar.

Example 3 Aqueous ammonia was added to a mixed aqueous solution of manganese chloride and magnesium chloride at a Mg / Mn molar ratio of 1: 2 to synthesize MgMn ₂ O ₄ . This MgMn ₂ O ₄ was prepared in Example 1.
A heat treatment was performed in the same manner as in Example 1, and Mg was extracted in the same manner as in Example 1 except that nitric acid was used.

The X-ray diffraction pattern of the obtained powder showed a pattern belonging to λ-MnO ₂ , as in Example 1. Also,
As a result of composition analysis by atomic absorption, the composition became Mg _0.2 Mn ₂ O _{4 and} the degree of oxidation of Mn was +3.9.

The undoped powder was ground and polished under the same conditions and the same evaluation method as in Example 1. However, the pH of the slurry was from 5.0 to 1.0. As a result, characteristics equivalent to those of Example 2 were shown.

[0047]

As described above in detail, according to the present invention, the general formula M _1-x Mn ₂ O ₄ (0 <X
<1) A novel polishing slurry containing a spinel-type manganese oxide represented by ≦ 1). The pH of the polishing slurry is set to 3.0 or less, and a semiconductor device in which a wiring material is made of Cu is polished. This enables highly accurate flattening.

[Brief description of the drawings]

FIG. 1 is a schematic view of a polishing apparatus according to an embodiment used in the present invention.

FIG. 2 is an X-ray diffraction diagram of the abrasive of the present invention.

FIG. 3 is an explanatory diagram of the first embodiment showing the effect of the present invention.

[Explanation of symbols]

 Reference Signs List 1 work plate 2 correction ring 3 surface plate 4 slurry supply nozzle

Claims (7)

[Claims] 1. A general formula M containing a different metal M at the 8A site
A polishing slurry comprising a spinel-type manganese oxide represented by _1-X Mn ₂ O ₄ (0 <X ≦ 1). 2. The polishing slurry according to claim 1, wherein the dissimilar metal M is at least one metal whose standard monopolar potential (E ⁰ ) is lower than that of manganese. 3. The polishing slurry according to claim 1, wherein the dissimilar metal M is at least one of Li, Zn and Mg. 4. The polishing slurry according to claim 1, wherein the dissimilar metal M at the 8A site is extracted by acid treatment. 5. The polishing slurry having a pH of 3.0 or less and a pH of 0.3 or less.
The polishing slurry according to claim 1, wherein the polishing slurry is one or more. 6. The polishing slurry according to claim 1, which is used for polishing and flattening a wiring material of a semiconductor integrated circuit. 7. The semiconductor integrated circuit according to claim 6, wherein the wiring material is copper, and the copper is polished and flattened.
The polishing slurry according to the above.