JP2020096190A - Polishing liquid for CMP and polishing method using the same - Google Patents

Abstract

To provide a polishing liquid for CMP (chemical mechanical polishing) capable of improving the polishing rate of ruthenium-based metals compared to using conventional CMP polishing liquid, and a polishing method using the same.SOLUTION: The polishing liquid for CMP is for polishing a ruthenium-based metal and contains abrasive grains, a metal oxidizer, and water, in which the metal oxidant has a redox potential accompanied by the transfer of hydroxide ion, the redox potential is 0.68 V or more with respect to the standard hydrogen electrode, the pH of the CMP polishing liquid is 7.0-13.0, and the content of abrasive grains is 0.10 pts.mass or more per 100 pts.mass of the content of the abrasive grains and the content of the water.SELECTED DRAWING: None

Description

The present invention relates to a CMP polishing liquid for polishing a ruthenium-based metal, and a polishing method using the same.

In recent years, a new fine processing technique has been developed along with higher integration and higher performance of semiconductor integrated circuits (LSI). The chemical mechanical polishing (CMP) method is one of such methods, and planarization of the interlayer insulating material, metal plug formation, and embedded wiring formation in the LSI manufacturing process (particularly, multilayer wiring forming process). It is a technique that is frequently used in such cases.

In recent years, a damascene method for forming damascene wiring has been mainly adopted in order to highly integrate and improve the performance of an LSI. An example of the damascene method will be described with reference to FIG. First, the groove portion (recess) 2 is formed on the surface of the insulating material 1 (FIGS. 1A and 1B). Next, the wiring metal 3 is deposited to fill the groove 2 (FIG. 1C). At this time, as shown in FIG. 1C, due to the influence of the unevenness of the insulating material 1, unevenness is formed on the surface of the wiring metal 3. Finally, the wiring metal 3 other than the portion embedded in the groove 2 is removed by CMP (FIG. 1D).

A copper-based metal (copper, copper alloy, etc.) is often used as the wiring metal (wiring portion metal). Copper-based metals can diffuse into the insulating material. In order to prevent this, a layered barrier metal is provided between the copper-based metal and the insulating material. As the barrier metal, tantalum-based metal, titanium-based metal, or the like is used. However, these barrier metals have low adhesion to copper-based metals. Therefore, in order to maintain the adhesion between the copper-based metal and the barrier metal, instead of forming the wiring portion directly on the barrier metal, a copper-based metal thin film called a seed layer (copper seed layer) is provided, and then the copper is not formed. It is common to deposit a base metal. That is, as shown in FIG. 2, the insulating material 1 having a concave portion on the surface, the barrier metal 4 provided on the insulating material 1 so as to follow the surface shape of the insulating material 1, and the shape of the barrier metal 4 are formed. A base (for example, a substrate) having a seed layer 5 provided on the barrier metal 4 so as to follow and a wiring metal 3 provided on the seed layer 5 so as to fill the recess and cover the entire surface. ) Is used.

In order to form the barrier metal 4 and the seed layer 5, a physical vapor deposition method (Physical Vapor Deposition, hereinafter referred to as “PVD method”) may be used. However, in the PVD method, as shown in FIG. 3A, in the vicinity of the opening of the groove (recess) formed in the insulating material 1, the metal (barrier metal or seed) formed on the inner wall surface of the groove by the PVD method is used. The thickness of the layer 6 tends to be partially thick. In this case, as the wiring becomes finer, as shown in FIG. 3B, the holes 7 become more prominent due to the metal provided on the inner wall surface of the groove contacting each other.

As a means for solving this problem, a method of using a ruthenium-based metal, which has excellent adhesion to a copper-based metal, has been studied. That is, a method of using a ruthenium-based metal as a seed layer in place of a copper-based metal, or a method of providing a ruthenium-based metal between a seed layer using a copper-based metal and a barrier metal has been proposed. The ruthenium-based metal can be formed by a chemical vapor deposition method (hereinafter referred to as “CVD method”) or an atomic layer deposition method (atomic layer deposition. Hereinafter referred to as “ALD method”). With the CVD method or the ALD method, it is easy to suppress the generation of voids and it is possible to cope with the formation of fine wiring.

When using a ruthenium-based metal, it is necessary to partially remove the ruthenium-based metal by CMP in the process of forming a damascene wiring. On the other hand, some methods of polishing a noble metal have been proposed. For example, using a polishing liquid containing abrasive particles and at least one additive selected from the group consisting of diketones, heterocyclic compounds, urea compounds and zwitterionic compounds, platinum, iridium, ruthenium, rhenium, rhodium , A method of polishing a noble metal such as palladium, silver, osmium, and gold has been proposed (see, for example, Patent Document 1 below). Further, a method of polishing a noble metal using a chemical mechanical polishing system containing an abrasive, a liquid carrier, and a sulfonic acid compound or a salt thereof has been proposed (for example, refer to Patent Document 2 below). Further, Patent Document 3 below discloses a CMP polishing liquid for polishing a substrate having a layer containing ruthenium, which contains an oxidizing agent, abrasive particles, water, and a compound having a guanidine structure. Have been described.

US Pat. No. 6,527,622 Japanese Patent Publication No. 2006-519490 International Publication No. 2009/054370

However, in conventional CMP polishing liquids for copper-based metals and CMP polishing liquids for barrier metals, since the CMP polishing liquids are not specialized for removing ruthenium-based metals, they are sufficient for ruthenium-based metals. A high polishing rate has not been obtained. Further, with respect to the CMP polishing liquid, it is desired to improve the polishing rate of the ruthenium-based metal as compared with the conventional one.

The present invention provides a CMP polishing liquid capable of improving the polishing rate of ruthenium-based metals as compared with the case of using a conventional CMP polishing liquid, and a polishing method using the same.

The present inventor, as a result of diligent studies, contains abrasive grains, a metal oxidant, and water, and the metal oxidant has a redox potential accompanied by transfer of hydroxide ions, and the redox The potential is 0.68 V or more with respect to the standard hydrogen electrode, the pH of the CMP polishing liquid is 7.0 to 13.0, and the content of the abrasive grains is the content of the abrasive grains and the water. By using a polishing liquid for CMP which is 0.10 parts by mass or more with respect to a total content of 100 parts by mass, the polishing rate of the ruthenium-based metal is increased as compared with the case of using the conventional polishing liquid for CMP. It was found that it can be improved.

That is, the CMP polishing liquid according to the present invention is a CMP polishing liquid for polishing a ruthenium-based metal, contains abrasive grains, a metal oxidizer, and water, and the metal oxidizer is It has an oxidation-reduction potential accompanied by transfer of hydroxide ions, the oxidation-reduction potential is 0.68 V or more with respect to a standard hydrogen electrode, and the polishing liquid for CMP has a pH of 7.0 to 13.0. The content of the abrasive grains is 0.10 parts by mass or more with respect to a total of 100 parts by mass of the content of the abrasive grains and the content of the water.

According to the CMP polishing liquid of the present invention, it is possible to improve the polishing rate of ruthenium-based metal as compared with the case of using the conventional CMP polishing liquid.

The present inventor has paid attention to a polishing liquid for CMP having a pH region in a neutral region or an alkaline region, and has an oxidation-reduction potential of 0. It has been found that when the pH of the polishing liquid for CMP containing the metal oxidant of 68 V or higher is 7.0 to 13.0, it is effective in polishing and removing the ruthenium-based metal at a high polishing rate. ..

Next, the present inventor polishes a ruthenium-based metal at a high polishing rate when the content of abrasive grains is 0.10 parts by mass or more based on 100 parts by mass of the total content of abrasive grains and the content of water. It was found to be effective in removing.

As described above, the polishing liquid for CMP according to the present invention contains abrasive grains, a metal oxidizer, and water, and the metal oxidizer has an oxidation-reduction potential accompanied by transfer of hydroxide ions. , The oxidation-reduction potential is 0.68 V or more with respect to the standard hydrogen electrode, the pH of the polishing liquid for CMP is 7.0 to 13.0, the content of abrasive grains is the content of abrasive grains and water. When the content is 0.10 parts by mass or more based on 100 parts by mass in total, the ruthenium-based metal can be removed by polishing at a high polishing rate.

The present inventor speculates as to the reason why the ruthenium-based metal can be removed by polishing (CMP removal) at a high polishing rate with the CMP polishing liquid according to the present invention. That is, first, a ruthenium-based metal is contacted with a metal oxidant having a redox potential of 0.68 V or higher accompanied by transfer of hydroxide ions in a neutral region or an alkaline region of pH 7.0 to 13.0. Then, a ruthenium oxide layer is formed on the surface of the ruthenium-based metal at a high speed. Then, the ruthenium oxide layer is polished at a high speed by polishing the ruthenium oxide layer with a polishing liquid containing 0.10 parts by mass or more of abrasive particles with respect to a total of 100 parts by mass of the content of abrasive particles and the content of water. Can be removed. When the ruthenium oxide layer is removed, a new ruthenium-based metal appears from the lower layer and is oxidized again by the metal oxidant. By repeating this, the ruthenium-based metal can be removed by polishing at a high polishing rate.

The redox potential is preferably 0.68 to 0.90 V with respect to the standard hydrogen electrode.

The ruthenium-based metal may include at least one selected from the group consisting of ruthenium, ruthenium alloys and ruthenium compounds.

The metal oxidant may contain at least one selected from the group consisting of hypochlorous acid, chlorous acid, hypobromite acid, orthoperiodic acid, xenonic acid, perxenonic acid and salts thereof. Thereby, the polishing rate of the ruthenium-based metal can be further improved.

The metal oxidizing agent may include at least one selected from the group consisting of sodium hypochlorite, calcium hypochlorite, sodium zincate and calcium zincate. Thereby, the polishing rate of the ruthenium-based metal can be further improved.

The polishing liquid for CMP according to the present invention may further contain a metal oxide dissolving agent. The metal oxide dissolving agent preferably contains an organic acid. As a result, metal etching can be easily suppressed.

The present inventor has an effect that a metal anticorrosive agent can form a complex with a ruthenium-based metal oxidized by the metal oxidizing agent, and a ruthenium-based metal is removed by polishing at a higher speed by using a metal anticorrosive agent. I found that I could do it. The CMP polishing liquid according to the present invention may further contain a metal anticorrosive agent. Thereby, the polishing rate of the ruthenium-based metal can be further improved. In addition, when the polishing liquid for CMP contains the metal anticorrosive, it is possible to prevent the conductive substance that is polished and removed at the same time as the barrier metal from being corroded when the substrate to be polished is a semiconductor substrate.

The metal anticorrosive agent preferably contains at least one selected from the group consisting of a compound having an imidazole skeleton, a compound having a triazole skeleton, a compound having a tetrazole skeleton, a compound having a pyrazole skeleton, and a compound having a pyrimidine skeleton. .. Thereby, the polishing rate of the ruthenium-based metal can be further improved.

The polishing liquid for CMP according to the present invention may further contain an organic solvent. Thereby, the polishing rate of the ruthenium-based metal can be further improved.

The polishing method according to the present invention includes an interlayer insulating material having a raised portion and a groove portion on the surface, a barrier metal provided so as to follow the surface of the interlayer insulating material, and a conductive material provided so as to cover the barrier metal. A first polishing step of polishing a conductive material in a substrate having a conductive substance to expose a barrier metal located on a raised portion of an interlayer insulating material, and a first polishing step using the polishing liquid for CMP described above. A second polishing step in which the barrier metal exposed in the polishing step is polished to expose the raised portion of the interlayer insulating material.

The interlayer insulating material may include at least one selected from the group consisting of silicon compounds and organic polymers.

The conductive substance preferably contains at least one selected from the group consisting of copper, copper alloys, copper oxides, and copper alloy oxides.

The barrier metal preferably contains at least one selected from the group consisting of ruthenium, ruthenium alloys and ruthenium compounds.

According to the present invention, the polishing rate of at least ruthenium-based metal can be improved as compared with the case of using the conventional CMP polishing liquid. According to the present invention, it is possible to provide application (use) of a polishing liquid for CMP to polishing a ruthenium-based metal. Further, according to the present invention, it is possible to provide an application (use) of the polishing liquid for CMP to polishing a substrate having a barrier metal (for example, a barrier layer) containing a ruthenium-based metal.

It is a cross-sectional schematic diagram which shows the damascene method which forms a damascene wiring. It is a cross-sectional schematic diagram which shows the base|substrate (for example, substrate) in which the seed layer is provided between the copper type metal and the barrier metal. It is a cross-sectional schematic diagram which shows the state of the metal formed by PVD method. It is a cross-sectional schematic diagram which shows the board|substrate in which the ruthenium type metal is provided instead of the copper seed layer. It is a cross-sectional schematic diagram which shows the board|substrate in which the ruthenium type metal is provided between the seed layer and the barrier metal. It is a cross-sectional schematic diagram which shows the process of polishing a base|substrate (for example, substrate) using the polishing liquid for CMP.

Hereinafter, embodiments of the present invention will be described in detail.

In the present specification, the numerical range indicated by using "to" indicates a range including the numerical values before and after "to" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of the numerical range of a certain stage may be replaced with the upper limit value or the lower limit value of the numerical range of another stage. In the numerical range described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.

Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. In the present specification, the amount of each component in the composition refers to the total amount of the plurality of substances present in the composition, unless a plurality of substances corresponding to each component are present in the composition. means. The terms "layer" and "film" include not only the structure of the shape formed on the entire surface but also the structure of the part formed when observed as a plan view.

<CMP polishing liquid>
The CMP polishing liquid according to the present embodiment is a CMP polishing liquid for polishing a ruthenium-based metal. The CMP polishing liquid according to the present embodiment contains at least abrasive grains, a metal oxidizer, and water. The metal oxidizing agent of the polishing liquid for CMP according to this embodiment has an oxidation-reduction potential accompanied by transfer of hydroxide ions, and the oxidation-reduction potential is 0.68 V or more with respect to the standard hydrogen electrode. The pH of the polishing liquid for CMP according to the present embodiment is 7.0 to 13.0 (7.0 or more and 13.0 or less). In the CMP polishing liquid according to the present embodiment, the content of the abrasive grains is 0.10 parts by mass or more with respect to the total 100 parts by mass of the content of the abrasive grains and the content of water.

[PH of polishing liquid for CMP]
The pH of the CMP polishing liquid according to the present embodiment is 7.0 to 13.0, and may be 7.0 or more and less than 13.0, from the viewpoint of increasing the polishing rate of the ruthenium-based metal. The pH of the CMP polishing liquid according to the present embodiment is preferably 7.5 to 12.0 from the viewpoint of further increasing the polishing rate of the ruthenium-based metal. Further, the pH of the CMP polishing liquid according to the present embodiment is more preferably 8.0 to 12.0, and more preferably 9.0 to 11.5, from the viewpoint of improving the dispersibility of the abrasive grains. Is more preferable. Since the pH is 7.0 or higher, etching of the conductive material (for example, metal such as copper and copper alloy) is compared with the polishing rate of the barrier metal as an additional effect as compared with the region of pH lower than 7.0. The speed can be suppressed. If the pH is higher than 13.0, the ruthenium-based metal will be corroded, so that the surface of the substrate (for example, substrate) polished by the CMP polishing liquid is likely to have irregularities. The pH is defined as the pH at a liquid temperature of 25°C.

The pH of the polishing liquid for CMP according to the present embodiment needs to be 7.0 to 13.0 and is desired by adjusting the content of a metal oxidizing agent (for example, an organic acid), a metal oxide dissolving agent, or the like. Can be adjusted to pH. The pH of the CMP polishing liquid according to the present embodiment can also be adjusted by adding potassium hydroxide. Further, the pH can be adjusted by adding an alkaline component such as amino acid, ammonia, sodium hydroxide or tetramethylammonium hydroxide.

In this embodiment, the pH of the polishing liquid for CMP can be measured with a pH meter (for example, model number: PH81 manufactured by Yokogawa Electric Co., Ltd.). The pH of the polishing liquid for CMP is a standard buffer solution (phthalate pH buffer solution [pH: 4.01 (25°C)], neutral phosphate pH buffer solution [pH: 6.86 (25°C)]. And borate pH buffer [pH: 9.12 (25°C)]), and after calibrating at 3 points, put the electrode into the polishing liquid for CMP and use the value after 2 minutes or more to stabilize can do.

The constituent components of the CMP polishing liquid will be described below.

[Abrasive]
The CMP polishing liquid according to the present embodiment contains abrasive grains. The abrasive grains (abrasive grain surface) preferably have a negative zeta potential (negative charge) from the viewpoint of easily suppressing aggregation of the abrasive grains, and have a zeta potential of -5 mV or less. Is more preferable, the zeta potential of −10 mV or less is more preferable, and the zeta potential of −20 mV or less is particularly preferable. The zeta potential of the abrasive grains can be easily adjusted by using generally commercially available abrasive grains (abrasive grains having a negative charge).

When the pH is in the neutral region or the alkaline region as in the CMP polishing liquid according to the present embodiment, the colloidal silica particles in such a CMP polishing liquid tend to have a zeta potential of -20 mV or less. is there. When the abrasive grains have a zeta potential of -20 mV or less as described above, it is possible to easily suppress the agglomeration of the abrasive grains and to disperse them well in the CMP polishing liquid.

To measure the zeta potential of the abrasive grains in the CMP polishing liquid, for example, Spectris Co., Ltd., trade name: Zetasizer 3000 HS (“Zetasizer” is a registered trademark) can be used. More specifically, the polishing liquid for CMP is diluted with water so that the recommended scattered light amount of Zetasizer 3000 HS is obtained, and the measurement is performed at room temperature (25° C.).

The abrasive grain is not particularly limited, but preferably contains at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania and modified products thereof. Colloidal silica may be used as the silica. Examples of the modified products include silica, alumina, ceria, titania, zirconia, germania, and the like, whose surface is modified with an alkyl group. The method of modifying the surface of the abrasive particles with an alkyl group is not particularly limited, and examples thereof include a method of reacting a hydroxyl group present on the surface of the abrasive particle with an alkoxysilane having an alkyl group.

The abrasive grains may be used alone or in combination of two or more.

The polishing liquid for CMP according to the present embodiment preferably contains abrasive grains having an average particle diameter of 10 to 100 nm, and contains abrasive grains having an average particle diameter of 10 to 100 nm and containing colloidal silica. More preferable. Further, the polishing liquid for CMP according to the present embodiment preferably contains abrasive grains having an average particle size of 25 to 80 nm, and contains abrasive grains having an average particle size of 25 to 80 nm and containing colloidal silica. Is more preferable. When the average particle size is 10 nm or more, it is possible to easily suppress a decrease in the polishing rate of the barrier metal. When the average particle diameter is 100 nm or less, it is possible to easily suppress deterioration of dispersion stability of abrasive grains in the CMP polishing liquid.

Here, the “average particle size” can be measured, for example, by the following method. That is, an appropriate amount of the CMP polishing liquid is weighed, and the CMP polishing liquid is diluted with water as necessary so that a measurement sample is obtained so that it falls within the range of the scattered light intensity required by the dynamic light scattering particle size distribution analyzer. Prepare. Next, this measurement sample is put into a dynamic light scattering type particle size distribution meter for measurement, and the value obtained as D50 is taken as the average particle size. As a dynamic light scattering type particle size distribution analyzer having such a function, for example, BECKMAN COULTER, trade name: COULTER N5 type (“COULTER” is a registered trademark) can be mentioned. Further, the value of D50 of the particle size distribution measurement result can be used as the average particle diameter of the abrasive grains in the CMP polishing liquid (hereinafter referred to as the average particle diameter).

The content of the abrasive grains is 0.10 parts by mass or more based on 100 parts by mass of the total content of the abrasive grains and the content of water, from the viewpoint of suppressing a decrease in the polishing rate of the ruthenium-based metal. The content of the abrasive grains is preferably 0.20 parts by mass or more, based on 100 parts by mass of the total content of the abrasive grains and the content of water, from the viewpoint of further increasing the polishing rate of the ruthenium-based metal. It is more preferably 0.50 parts by mass or more, still more preferably 1.00 parts by mass or more, particularly preferably 1.50 parts by mass or more, very preferably 2.00 parts by mass or more, and very preferably 2.50 parts by mass or more. The content of the abrasive grains may be 5.00 parts by mass or more, 7.50 parts by mass or more, or 10.00 parts by mass or more. The content of the abrasive grains is preferably 50.00 parts by mass or less, based on 100 parts by mass of the total content of the abrasive grains and the content of water, from the viewpoint that the occurrence of polishing scratches is likely to be suppressed, and 40 It is more preferably 0.000 parts by mass or less, further preferably 25.00 parts by mass or less, particularly preferably 20.00 parts by mass or less, and most preferably 15.00 parts by mass or less.

[Metal oxidizer]
The CMP polishing liquid according to the present embodiment contains a metal oxidizing agent. The metal oxidant has a redox potential accompanied by transfer of hydroxide ions. The polishing liquid for CMP according to the present embodiment contains a metal oxidizer A having a redox potential of 0.68 V or more with respect to a standard hydrogen electrode (NHE) from the viewpoint of improving the polishing rate of a ruthenium-based metal. ing. From the viewpoint of further improving the ruthenium-based metal polishing rate, the redox potential is preferably 0.70 V or higher, more preferably 0.75 V or higher, further preferably 0.80 V or higher, and particularly preferably 0.85 V or higher. The redox potential is preferably 0.90 V or less, and more preferably 0.89 V or less, from the viewpoint of further improving the polishing rate of the ruthenium-based metal. From these viewpoints, the redox potential is preferably 0.68 to 0.90 V, more preferably 0.68 to 0.89 V, and may be 0.70 to 0.90 V.

The metal oxidizer A is not particularly limited, but examples thereof include hypochlorous acid, chlorous acid, hypobromite, orthoperiodic acid, xenonic acid, perxenonic acid, and salts thereof. Examples of the salt include ammonium salt, potassium salt, sodium salt, calcium salt and the like. Specific examples include sodium hypochlorite, calcium hypochlorite, sodium zincate and calcium zincate. Hypochlorous acid and hypochlorite containing hypochlorite ion (ClO ⁻ ) exchange a hydroxide ion according to the formula “Cl ⁻ +2OH ⁻ ⇔ ClO ⁻ +H ₂ O +2e ⁻ ”. It has an associated redox potential (0.89 V). As the metal oxidizer A, at least one selected from the group consisting of hydroxylamine and silver oxide may be used from the viewpoint of further improving the polishing rate of a ruthenium-based metal.

The polishing liquid for CMP according to the present embodiment may further contain a metal oxidant B having a redox potential of less than 0.68 V (a redox potential accompanied by transfer of hydroxide ions) with respect to the standard hydrogen electrode. Good. Examples of the metal oxidizer B include ammonia.

Each of the metal oxidizer A and the metal oxidizer B can be used alone or in combination of two or more.

The content of the metal oxidizer (the total amount of the metal oxidizer A and the metal oxidizer B) is sufficient to oxidize the metal and tends to further improve the polishing rate of the ruthenium-based metal. 0.005 parts by mass or more is preferable, 0.01 parts by mass or more is more preferable, 0.02 parts by mass or more is further preferable, and 0.025 parts by mass or more is per 100 parts by mass of the total amount and the content of water. Is particularly preferable. The content of the metal oxidizing agent may be 0.05 parts by mass or more, 0.10 parts by mass or more, 0.50 parts by mass or more, and 1.00 parts by mass. It may be the above or 1.50 parts by mass or more. The content of the metal oxidizer (the total amount of the metal oxidizer A and the metal oxidizer B) is such that the occurrence of roughness on the surface to be polished tends to be easily suppressed, and the content of the abrasive grains and water The total content is 100 parts by mass, preferably 5.00 parts by mass or less, more preferably 4.00 parts by mass or less, and further preferably 2.00 parts by mass or less. From these viewpoints, the content of the metal oxidizer (the total amount of the metal oxidizer A and the metal oxidizer B) is 0.005 to 100 parts by mass in total of the content of the abrasive grains and the content of water. 5.00 parts by mass is preferable, 0.01 to 4.00 parts by mass is more preferable, and 0.02 to 2.00 parts by mass is further preferable.

The content of the metal oxidizer A is such that the metal is easily oxidized sufficiently and the polishing rate of the ruthenium-based metal tends to be further improved, so that the total content of the abrasive grains and the content of water is 100 parts by mass. 0.005 parts by mass or more is preferable, 0.01 parts by mass or more is more preferable, 0.02 parts by mass or more is further preferable, and 0.025 parts by mass or more is particularly preferable. The content of the metal oxidizer A may be 0.03 parts by mass or more, 0.04 parts by mass or more, and may be 0.05 parts by mass or more. The content of the metal oxidizer A is 5 parts by mass with respect to the total of 100 parts by mass of the content of the abrasive grains and the content of water from the viewpoint that roughening of the surface to be polished tends to be easily suppressed. It is preferably at most 4 parts by mass, more preferably at most 4 parts by mass, still more preferably at most 2 parts by mass.

Ratio of the content of the metal oxidizer A in the content of the metal oxidizer (the total amount of the metal oxidizer A and the metal oxidizer B) (the content of the metal oxidizer A/the total of the metal oxidizer A and the metal oxidizer B) The amount) is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and 1.5 from the viewpoint that the metal is easily oxidized sufficiently and the polishing rate of the ruthenium-based metal tends to be further improved. It is more preferably at least mass%. The upper limit of the ratio of the content of the metal oxidizing agent A to the content of the metal oxidizing agent is 100% by mass or less. The ratio of the content of the metal oxidant A to the content of the metal oxidant may be 10% by mass or less, 5% by mass or less, or 3.5% by mass or less, It may be 2.0% by mass or less.

[Metal oxide dissolving agent]
The polishing liquid for CMP according to this embodiment may contain a metal oxide dissolving agent. Examples of the metal oxide-dissolving agent include compounds such as organic acids, organic acid esters, salts of organic acids (for example, ammonium salts), inorganic acids, salts of inorganic acids (for example, ammonium salts) (for metal anticorrosive agents described later). Corresponding compounds and compounds corresponding to metal oxidizers) are included, and there is no particular limitation as long as they are water-soluble. Examples of the metal oxide dissolving agent include guanidine carbonate, diaminopyridine (for example, 2,3-diaminopyridine), formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethyl. Butyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malon Organic acids such as acids, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, p-toluenesulfonic acid, lactic acid, quinaldic acid; these organic acid esters; Examples thereof include ammonium salts of organic acids; inorganic acids such as hydrochloric acid and chromic acid; ammonium salts of inorganic acids such as ammonium chloride, ammonium dichromate, and ammonium dichromate. Among these, organic acids are preferable from the viewpoint of easily suppressing metal etching. Examples of the organic acid include guanidine carbonate, diaminopyridine, glycolic acid, lactic acid, succinic acid, adipic acid, glutaric acid, malic acid, malonic acid, maleic acid, tartaric acid, benzoic acid, salicylic acid, quinaldic acid, butyric acid and valeric acid. At least one selected from the group consisting of is preferred. The metal oxide dissolving agent may be used alone or in combination of two or more.

The content of the metal oxide dissolving agent is the content of the abrasive grains from the viewpoint that the ruthenium-based metal is removed by polishing at a higher speed, and that the reduction in the polishing rate of the conductive substance and the barrier metal tends to be suppressed. And 0.02 parts by mass or more, more preferably 0.03 parts by mass or more, further preferably 0.05 parts by mass or more, and 0.10 parts by mass or more with respect to a total of 100 parts by mass of the water content. Particularly preferred. The content of the metal oxide dissolving agent may be 0.30 parts by mass or more, 0.50 parts by mass or more, 0.60 parts by mass or more, 0.70 parts by mass. Parts or more, 1.00 parts by mass or more, 1.20 parts by mass or more, 1.50 parts by mass or more, 1.70 parts by mass or more May be The content of the metal oxide dissolving agent is 100 in total of the content of the abrasive grains and the content of water from the viewpoint that the etching is easily suppressed and the surface to be polished is easily suppressed from being roughened. The amount is preferably 5.00 parts by mass or less, more preferably 3.00 parts by mass or less, still more preferably 2.00 parts by mass or less, relative to the parts by mass. From these viewpoints, the content of the metal oxide dissolving agent is preferably 0.02 to 5.00 parts by mass, and 0.03 to 3 parts by mass with respect to 100 parts by mass in total of the content of the abrasive grains and the content of water. 0.00 parts by mass is more preferable, and 0.05 to 2.00 parts by mass is further preferable.

[Metallic anticorrosive]
The CMP polishing liquid according to the present embodiment may contain a metal anticorrosive agent. The metal anticorrosive agent is not particularly limited as long as it is a substance having an action of forming a protective film on the metal surface, but conventionally known as long as it has an effective amount of water solubility to exert the effect. The substances described above can be used without particular limitation. The metal anticorrosive agent may be used alone or in combination of two or more. Specific examples of the metal anticorrosive agent include anthranilic acid, salicylaldoxime, a compound having an imidazole skeleton (hereinafter referred to as “imidazole compound”), and a compound having a triazole skeleton (hereinafter referred to as “triazole compound”). ), a compound having a tetrazole skeleton (hereinafter referred to as “tetrazole compound”), a compound having a pyrazole skeleton (hereinafter referred to as “pyrazole compound”), a compound having a pyrimidine skeleton (hereinafter referred to as “pyrimidine compound”). .) and the like. Among them, at least one selected from the group consisting of imidazole compounds, triazole compounds, tetrazole compounds, pyrazole compounds and pyrimidine compounds is preferable, and triazole compounds are more preferable.

Examples of the imidazole compound include 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole. , 2-undecylimidazole, 2-aminoimidazole and the like.

Examples of the triazole compound include 1,2,3-triazole; 1,2,4-triazole; 3-amino-1H-1,2,4-triazole and 1-acetyl-1H-1,2,3-triazolo[4. ,5-b]Pyridine, 1H-1,2,3-triazolo[4,5-b]pyridine, 1,2,4-triazolo[4,3-a]pyridin-3(2H)-one, 3H- Triazole derivatives such as 1,2,3-triazolo[4,5-b]pyridin-3-ol; benzotriazole; 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxyl-1H-benzotriazole, 4-carboxyl-1H-benzotriazole methyl ester, 4-carboxyl-1H-benzotriazole butyl ester, 4-carboxyl-1H-benzotriazole octyl ester, 5- Hexylbenzotriazole, [1,2,3-benzotriazolyl-1-methyl][1,2,4-triazolyl-1-methyl][2-ethylhexyl]amine, tolyltriazole, naphthotriazole, bis[(1 Examples thereof include benzotriazolyl)methyl]phosphonic acid and benzotriazole derivatives such as 3-aminotriazole. Among them, at least one selected from the group consisting of benzotriazole and benzotriazole derivatives is preferable.

Examples of the tetrazole compound include 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 1-(2-diaminoethyl)-5-mercaptotetrazole and the like. ..

Examples of the pyrazole compound include 3,5-dimethylpyrazole, 3-amino-5-methylpyrazole, 4-methylpyrazole, 3-amino-5-hydroxypyrazole and the like.

Examples of the pyrimidine compound include pyrimidine, 1,2,4-triazolo[1,5-a]pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, 1,3-Diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trihydroxy Pyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4-diamino-6-hydroxyl Pyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, 2-methyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine, 2-methylsulfa Nyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine, 2-methylsulfanyl-5,7-diphenyl-4,7-dihydro-(1,2,4) Examples thereof include triazolo(1,5-a)pyrimidine and 4-aminopyrazolo[3,4-d]pyrimidine.

The content of the metal anticorrosive agent is such that it is easy to suppress the etching of the conductive substance (for example, the metal for the wiring part), and it is easy to suppress the occurrence of roughness on the surface to be polished. 0.01 mass part or more is preferable, 0.05 mass part or more is more preferable, 0.10 mass part or more is still more preferable, and 0.20 mass is relative to the total 100 mass parts of the content of water and the content of water. Part or more is particularly preferable. The content of the metal anticorrosive may be 0.25 parts by mass or more, may be 0.40 parts by mass or more, may be 0.50 parts by mass or more, and may be 0.75 parts by mass. It may be the above or more, and may be 1.00 parts by mass or more. The content of the metal anticorrosive agent is 100 in total of the content of the abrasive grains and the content of water from the viewpoint that the decrease in the polishing rate of the conductive substance (for example, the metal for the wiring portion) and the barrier metal tends to be suppressed. The amount is preferably 10.00 parts by mass or less, more preferably 5.00 parts by mass or less, still more preferably 2.00 parts by mass or less. From these viewpoints, the content of the metal anticorrosive agent is preferably 0.01 to 10.00 parts by mass, and 0.05 to 5.5 parts by mass with respect to the total of 100 parts by mass of the content of the abrasive grains and the content of water. 00 parts by mass is more preferable, and 0.10 to 2.00 parts by mass is further preferable.

[Water-soluble polymer]
The CMP polishing liquid according to the present embodiment may further contain a water-soluble polymer. The weight average molecular weight (Mw) of the water-soluble polymer is preferably 500 or more, more preferably 1500 or more, still more preferably 5000 or more. The upper limit of the weight average molecular weight of the water-soluble polymer is not particularly limited, but is preferably 5,000,000 or less from the viewpoint of excellent solubility. When the weight average molecular weight of the water-soluble polymer is 500 or more, a higher polishing rate for the ruthenium-based metal tends to be obtained. The weight average molecular weight of the water-soluble polymer can be measured by gel permeation chromatography (GPC) under the following conditions using a calibration curve of standard polystyrene.

(GPC condition)
Sample: 10 μL
Standard polystyrene: manufactured by Tosoh Corporation, standard polystyrene (molecular weight: 190000, 17900, 9100, 2980, 578, 474, 370, 266).
Detector: Hitachi, RI-monitor, product name: L-3000
Integrator: Hitachi, Ltd., GPC integrator, product name: D-2200
Pump: Hitachi, Ltd., trade name: L-6000
Degassing device: Showa Denko KK, trade name: Shodex DEGAS (“SHODEX” is a registered trademark)
Column: Hitachi Chemical Co., Ltd., trade name: GL-R440, GL-R430, GL-R420 are connected in this order and used Eluent: Tetrahydrofuran (THF)
Measurement temperature: 23 ℃
Flow rate: 1.75 mL/min
Measurement time: 45 min

The water-soluble polymer is not particularly limited, and examples thereof include at least one selected from the group consisting of polycarboxylic acids, salts of polycarboxylic acids, polycarboxylic acid esters, polysaccharides, and vinyl polymers. As the water-soluble polymer, polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly(p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, Polycarboxylic acids such as aminopolyacrylamide and polyglyoxylic acid; polycarboxylic acids such as ammonium polymethacrylate, sodium polymethacrylate, ammonium polyacrylate, sodium polyacrylate, ammonium polyamic acid and sodium polyamic acid Acid salts; polycarboxylic acid esters such as polyaspartic acid ester, polyglutamic acid ester, polymethacrylic acid ester, polyamic acid ester, polymaleic acid ester, polyfumaric acid ester, polyacrylic acid ester; alginic acid, pectic acid, carboxymethylcellulose Examples thereof include polysaccharides such as sucrose, agar, cardan and pullulan; and vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone and polyacrolein. The water-soluble polymer may be used alone or in combination of two or more.

The content of the water-soluble polymer is 0.001 relative to 100 parts by mass of the total content of the abrasive grains and the content of water, from the viewpoint that roughening of the surface to be polished tends to be easily suppressed. The amount is preferably at least parts by mass, more preferably at least 0.002 parts by mass, still more preferably at least 0.005 parts by mass. From the viewpoint that the stability of the abrasive grains contained in the polishing liquid for CMP tends to improve, the content of the water-soluble polymer is 15. With respect to 100 parts by mass of the total content of the abrasive grains and the content of water. The amount is preferably 00 parts by mass or less, more preferably 10.00 parts by mass or less, still more preferably 5.00 parts by mass or less. From these viewpoints, the content of the water-soluble polymer is preferably 0.001 to 15.00 parts by mass, and 0.002 to 10. parts with respect to the total of 100 parts by mass of the content of the abrasive grains and the content of water. 00 parts by mass is more preferable, and 0.005 to 5.00 parts by mass is further preferable.

[Organic solvent]
The CMP polishing liquid according to the present embodiment may further contain an organic solvent. The organic solvent is not particularly limited, but a solvent that can be arbitrarily mixed with water is preferable.

Specific examples of the organic solvent include carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactones such as butyrolactone and propyl lactone; ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, Glycols such as triethylene glycol and tripropylene glycol; ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monoethyl ether, Propylene glycol monoethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monopropyl ether, diethylene glycol monopropyl ether, di Propylene glycol monopropyl ether, triethylene glycol monopropyl ether, tripropylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether Glycol monoethers such as butyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, diethylene glycol diethyl ether, dipropylene Glycol diethyl ether, triethylene glycol diethyl ether, tripropylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol dipropyl ether, diethylene glycol dipropyl ether, dipropylene glycol dipro Pill ether, triethylene glycol dipropyl ether, tripropylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, triethylene glycol dibutyl ether, tripropylene glycol dibutyl ether, etc. Derivatives of glycols such as glycol diethers; tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethers such as ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate; methanol, ethanol, propanol, Alcohols such as n-butanol, n-pentanol, n-hexanol, isopropanol (isopropyl alcohol) and 3-methyl-3-methoxybutanol; ketones such as acetone and methyl ethyl ketone; phenols such as phenol; dimethylformamide and the like Amides; sulfolanes such as sulfolane; N-methylpyrrolidone; ethyl lactate. Among them, carbonic acid esters, lactones, glycols and their derivatives, ethers from the viewpoint that additives (metal anticorrosives, etc.) can be easily dispersed in the polishing liquid, and that they can be easily mixed with water. , At least one selected from the group consisting of alcohols, ketones, phenols, amides and sulfolanes, and more preferably at least one selected from the group consisting of glycol monoethers, alcohols and carbonates. . The organic solvent may be used alone or in combination of two or more.

The content of the organic solvent is 100 parts by mass in total of the content of the abrasive grains and the content of water from the viewpoint that the wettability of the polishing liquid with respect to the substrate (for example, the substrate) tends to be easily suppressed. On the other hand, 0.10 parts by mass or more is preferable, 0.20 parts by mass or more is more preferable, 0.50 parts by mass or more is further preferable, and 0.75 parts by mass or more is particularly preferable. The content of the organic solvent may be 1.00 parts by mass or more, 2.00 parts by mass or more, 3.00 parts by mass or more, and 4.00 parts by mass or more. May be The content of the organic solvent is 50.00 parts by mass or less based on 100 parts by mass of the total content of the abrasive grains and the content of water from the viewpoint that the dispersibility tends to be easily suppressed. Is preferred, 30.00 parts by mass or less is more preferred, 10.00 parts by mass or less is still more preferred, and 5 parts by mass or less is particularly preferred. From these viewpoints, the content of the organic solvent is preferably 0.10 to 50.00 parts by mass, and 0.20 to 30.00 parts with respect to 100 parts by mass in total of the content of the abrasive grains and the content of water. A mass part is more preferable, and 0.50-10.00 mass parts is still more preferable.

[Preservation method]
The CMP polishing liquid according to the present embodiment may be stored as a one-liquid polishing liquid containing at least abrasive grains, a metal oxidizer, and water, and a slurry (first liquid) and an addition liquid (second liquid). Liquid) may be mixed and stored as a plural-liquid type (eg, two-liquid type) polishing liquid set in which the constituent components of the polishing liquid are divided into a slurry and an additive liquid so as to form the polishing liquid. .. The slurry contains, for example, at least abrasive grains and water. The additive liquid contains, for example, at least a metal oxidant and water. The metal oxidizing agent and other additives are preferably contained in the additive liquid among the slurry and the additive liquid.

In the polishing liquid set, the slurry and the additive liquid are mixed immediately before or during polishing to prepare a polishing liquid. In addition, the one-component polishing liquid may be stored as a storage liquid for polishing liquid in which the content of water is reduced, and may be used by diluting with water during polishing. The plural-liquid type polishing liquid set may be stored as a slurry storage liquid and an additive liquid storage liquid having a reduced water content, and may be used by diluting with water during polishing.

<Polishing method>
The CMP polishing liquid according to this embodiment can be applied to the formation of a wiring layer in a semiconductor device. The CMP polishing liquid according to the present embodiment can be used for CMP of a base (for example, a substrate) having a conductive substance, a barrier metal, and an interlayer insulating material, for example. The shapes of the conductive substance, the barrier metal and the interlayer insulating material are, for example, layered or film-shaped (for example, the conductive substance layer, the barrier layer and the interlayer insulating film). In CMP under the same conditions, the polishing rate ratio of conductive material/barrier metal/interlayer insulating material is preferably 0.1/1/1/0.1-1.

Examples of the constituent material of the interlayer insulating material include at least one selected from the group consisting of silicon compounds and organic polymers. As the silicon-based compound, silicon dioxide, fluorosilicate glass, trimethylsilane, a silica-based compound such as silicon oxynitride or hydrogenated silsesquioxane obtained by using dimethoxydimethylsilane as a starting material; silicon carbide; silicon Night ride etc. are mentioned. Examples of organic polymers include wholly aromatic low-dielectric constant interlayer insulating materials. Of these, silicon dioxide is particularly preferable. These materials (for example, a film) can be formed (for example, a film) by a CVD method, a spin coat method, a dip coat method or a spray method. As a specific example of the interlayer insulating material, an interlayer insulating material in an LSI manufacturing process (in particular, a multilayer wiring forming process) can be mentioned.

Examples of the constituent material of the conductive material include copper, copper alloys, copper oxides, oxides of copper alloys, tungsten, tungsten alloys, silver, gold, and other materials containing metal as a main component. Copper-based materials such as alloys, copper oxides, copper alloy oxides are preferred. As the conductive substance, the above substance (for example, a film) formed by a known sputtering method or plating method can be used.

The barrier metal is formed to prevent the constituent material of the conductive material from diffusing into the interlayer insulating material and to improve the adhesion between the interlayer insulating material and the conductive material. As the barrier metal, a tungsten-based metal such as tungsten, a tungsten alloy, a tungsten compound (eg, tungsten nitride); a titanium-based metal such as titanium, a titanium alloy, a titanium compound (eg, titanium nitride); a tantalum, a tantalum alloy, a tantalum compound. (Eg, tantalum nitride) and other tantalum-based metals; ruthenium, ruthenium alloys, ruthenium compounds (eg, ruthenium nitride) and other ruthenium-based metals; cobalt, cobalt alloys, cobalt compounds (eg, cobalt nitride) and other cobalt-based metals, Manganese-based metals such as manganese, manganese alloys, and manganese compounds (eg, manganese nitride) are preferred, and at least one selected from the group consisting of tantalum-based metals, cobalt-based metals and ruthenium-based metals is more preferred, and ruthenium-based metals are preferred. More preferable. The barrier metal may have a single layer structure composed of one of these or a laminated structure composed of two or more layers. The term "alloy" refers to, for example, a metal content of which exceeds 50% by mass.

As a polishing device, for example, when polishing with a polishing cloth (polishing pad), a holder that can hold a substrate (for example, a substrate) to be polished, a motor that can change the number of revolutions, and the like are attached and the polishing cloth is attached. A general polishing apparatus having a possible polishing platen can be used. The polishing cloth is not particularly limited, and general non-woven fabric, foamed polyurethane, porous fluororesin and the like can be used.

The polishing conditions are not limited, but the rotation speed of the surface plate is preferably a low rotation of 200 min ⁻¹ or less so that the substrate does not jump out. The pressing pressure of the substrate (for example, a semiconductor substrate) having the surface to be polished against the polishing cloth is preferably 1 to 100 kPa, and in order to satisfy the uniformity of the polishing rate within the surface and the flatness of the pattern. , 2 to 50 kPa is more preferable. During polishing, it is preferable to continuously supply the polishing liquid for CMP according to this embodiment to the polishing cloth with a pump or the like. Although there is no limitation on the supply amount, it is preferable that the surface of the polishing cloth is always covered with the polishing liquid.

It is preferable that the substrate after completion of polishing is thoroughly washed in running water and then dried by spin drying or the like to remove water droplets adhering to the substrate. Further, it is more preferable to use a known cleaning method in which a commercially available cleaning liquid is allowed to flow over the surface of the substrate, and a brush made of polyurethane is rotated and pressed at a constant pressure to remove deposits on the substrate, followed by drying. ..

In order to carry out chemical mechanical polishing with the surface state of the polishing cloth always the same, it is preferable to perform a conditioning step of the polishing cloth before polishing. For example, a dresser with diamond particles is used to condition the polishing cloth with a liquid containing at least water. Subsequently, it is preferable to perform the substrate cleaning step after performing the polishing method according to the present embodiment.

The polishing method according to the present embodiment is provided, for example, by following an interlayer insulating material (for example, an interlayer insulating film) having a convex portion (raised portion) and a concave portion (groove portion) on the surface and the surface of the interlayer insulating material. A conductive substance in a base (eg, substrate) having a barrier metal (eg, barrier layer) and a conductive substance (eg, conductive substance layer) provided so as to cover the barrier metal. The first polishing step of exposing the barrier metal located on the convex portion of the interlayer insulating material, and the barrier metal exposed by the first polishing step are polished by using the CMP polishing liquid according to the present embodiment. A second polishing step of exposing the convex portion of the insulating material. The conductive substance may cover the barrier metal so as to fill the concave portion of the interlayer insulating material.

The polishing method according to the present embodiment can be suitably used in the second polishing step of polishing the barrier metal, and can suppress the occurrence of seams in the metal wiring portion.

Next, the polishing method according to the present embodiment will be described in more detail with reference to the drawings in some cases by exemplifying a case where the base body is a semiconductor substrate. An example of using a ruthenium-based metal when the base body is a semiconductor substrate is a damascene wiring forming step.

For example, as shown in FIG. 4, a method of using a barrier layer containing a ruthenium-based metal as a seed layer instead of the copper seed layer can be used. In FIG. 4, reference numeral 11 is an interlayer insulating film, reference numeral 12 is a first barrier layer, reference numeral 13 is a second barrier layer, and reference numeral 14 is a conductive material layer. The second barrier layer 13 contains a ruthenium-based metal. In the semiconductor substrate shown in FIG. 4, for example, a groove (recess) is formed on the surface of the interlayer insulating film 11, and the first barrier layer 12 is provided so as to follow the shape of the surface of the interlayer insulating film 11. Formed on the first barrier layer 12, and then the second barrier layer 13 is formed on the first barrier layer 12 so as to follow the shape of the first barrier layer 12, and finally, the recesses are filled and the entire surface is covered. It is obtained by forming the conductive material layer 14 on the second barrier layer 13 as described above. As a method for forming the barrier layer, a method other than the PVD method is preferable, at least one method selected from the group consisting of the CVD method and the ALD method is more preferable, and the CVD method is further preferable. Accordingly, when forming fine wiring (for example, wiring width of 15 nm or less), it is possible to further suppress the formation of voids in the wiring portion, and it is preferable when polishing is performed using the CMP polishing liquid according to the present embodiment. It becomes easy to remove the barrier layer at a high polishing rate.

Further, as shown in FIG. 5, a method of providing the second barrier layer 13 between the first barrier layer 12 and the seed layer 15 using a wiring metal (for example, copper) can be mentioned. That is, the semiconductor substrate having the structure shown in FIG. 5 is obtained by adding the step of forming the seed layer 15 using the wiring metal after forming the second barrier layer 13 in FIG.

The step of polishing the substrate using the CMP polishing liquid according to this embodiment will be described with reference to FIG. In FIG. 6, reference numeral 11 is an interlayer insulating film, reference numeral 12 is a first barrier layer, reference numeral 13 is a second barrier layer, and reference numeral 14 is a conductive material layer. The second barrier layer 13 contains a ruthenium-based metal. FIG. 6A is a cross-sectional view showing the state of the substrate before polishing, FIG. 6B is a cross-sectional view showing the state of the substrate after the first polishing step, and FIG. FIG. 6B is a cross-sectional view showing the state of the substrate after the second polishing step.

First, the conductive material layer 14 is polished using a CMP polishing liquid for a conductive material to expose the second barrier layer 13 present on the convex portion of the interlayer insulating film 11, and then, as shown in FIG. A substrate having a structure shown in () is obtained (first polishing step). Then, the second barrier layer 13 and the first barrier layer 12 existing on the convex portion of the interlayer insulating film 11 and a part of the conductive substance layer 14 existing in the concave portion of the interlayer insulating film 11 are polished. The convex portion of the interlayer insulating film 11 is exposed to obtain the substrate shown in FIG. 6C (second polishing step). Of the two polishing steps, it is preferable to use the CMP polishing liquid according to the present embodiment in at least the second polishing step. Further, in order to improve the flatness, in the second polishing step, polishing may be continued (over-polishing) for a predetermined time after the interlayer insulating film 11 is exposed.

Hereinafter, the polishing method according to the present embodiment will be further described by taking the formation of a wiring layer in a semiconductor device as an example.

First, an interlayer insulating film such as silicon dioxide is laminated on a silicon substrate. Then, a well-known means such as resist layer formation and etching is used to form recesses (substrate exposed portions) having a predetermined pattern on the surface of the interlayer insulating film, to obtain an interlayer insulating film having protrusions and recesses. A barrier layer containing tantalum or the like is formed on the interlayer insulating film by vapor deposition or CVD to obtain a barrier layer covering the interlayer insulating film along the unevenness of the surface. Further, a conductive material layer containing copper or the like is formed by vapor deposition, plating, CVD or the like so as to fill the recess and cover the barrier layer. In the substrate thus obtained, the thickness of the interlayer insulating film is preferably about 0.01 to 2.0 μm, the thickness of the barrier layer is preferably about 0.001 to 0.1 μm, and the thickness of the conductive material layer is The thickness is preferably about 0.01 to 3.0 μm.

Next, for example, the conductive substance layer on the surface of the base is polished by CMP using a polishing liquid for a conductive substance having a sufficiently large polishing rate ratio of the conductive substance layer/barrier layer (first polishing step). ). As a result, a desired conductor pattern is obtained in which the barrier layer located on the convex portion of the interlayer insulating film is exposed on the surface and the conductive material layer is left in the concave portion. When this polishing proceeds, a part of the barrier layer located on the convex portion of the interlayer insulating film may be polished simultaneously with the conductive material layer. The patterned surface obtained by the first polishing step can be polished using the CMP polishing liquid according to the present embodiment as a surface to be polished in the second polishing step.

In the second polishing step, while the surface to be polished of the obtained substrate is pressed against the polishing cloth, the polishing plate for CMP according to the present embodiment is supplied between the polishing cloth and the surface to be polished while polishing the surface plate. And the substrate are moved relative to each other to polish the barrier layer exposed in the first polishing step. The polishing liquid for CMP according to this embodiment can polish the conductive material layer, the barrier layer, and the interlayer insulating film, but in the second polishing step, at least the exposed barrier layer is polished.

All the convex portions of the interlayer insulating film covered with the barrier layer are exposed, the conductive material layer to be the wiring layer (metal wiring portion) is left in the concave portion, and the cross section of the barrier layer is formed at the boundary between the convex portion and the concave portion. The polishing is completed when the exposed desired pattern is obtained.

In order to secure more excellent flatness at the end of polishing, overpolishing may be performed and polishing may be performed to a depth including a part of the convex portion of the interlayer insulating film. For example, when the time required to obtain a desired pattern in the second polishing step is 100 seconds, polishing for 50 seconds in addition to polishing for 100 seconds is referred to as overpolishing 50%.

An interlayer insulating film and a second-layer metal wiring are further formed on the metal wiring thus formed, and an interlayer insulating film is formed again between and on the wiring, and then polished to form a substrate (for example, , The semiconductor substrate) to be a smooth surface. By repeating this process a predetermined number of times, a semiconductor device having a desired number of wiring layers can be manufactured.

The CMP polishing liquid according to the present embodiment can be used not only for polishing a metal film formed on a substrate (for example, a semiconductor substrate) as described above, but also for polishing a substrate such as a magnetic head. ..

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples without departing from the technical idea of the present invention. For example, the type of the material of the polishing liquid and the compounding ratio thereof may be types and ratios other than the types and ratios described in the present embodiment, and the composition and structure to be polished are also compositions and structures other than those described in the present embodiment. And the structure does not matter.

[Preparation of polishing liquid for CMP]
(Example 1)
2.50 parts by mass of commercially available colloidal silica having an average particle size of 60 nm and a zeta potential of about -20 mV, sodium hypochlorite 0.025 parts by mass, ammonia 0.50 parts by mass, guanidine carbonate 1.00 parts by mass. Parts, 2,3-diaminopyridine 0.10 parts by mass, benzotriazole 0.50 parts by mass, 3-methyl-3-methoxybutanol 2.00 parts by mass, and pure water 97.50 parts by mass were mixed and mixed. After that, the mixture was stirred to prepare CMP polishing liquid 1.

(Examples 2 to 15 and Comparative Examples 1 and 2)
The components shown in Tables 1 to 3 were weighed and mixed, and then the mixture was stirred and operated in the same manner as in Example 1 to prepare polishing liquids 2 to 17 for CMP.

[Evaluation of polishing liquid for CMP]
(Evaluation of pH)
The pH of the CMP polishing liquids 1 to 17 was measured using a product name: PH81 manufactured by Yokogawa Electric Corporation. Standard buffer (phthalate pH buffer [pH: 4.01 (25°C)], neutral phosphate pH buffer [pH: 6.86 (25°C)] and borate pH buffer [pH : 9.12 (25° C.)]), the electrode was placed in the CMP polishing liquid, and the value (25° C.) after stabilizing for 2 minutes or more was determined as the pH of the CMP polishing liquid. And The results are shown in Tables 1 to 3.

(Evaluation of zeta potential)
The zeta potential (25° C.) of the abrasive grains in the CMP polishing liquids 1 to 17 was measured using Spectris Co., Ltd., trade name: Zetasizer 3000 HS. As a result, the zeta potential in the CMP polishing liquid 13 exceeded -20 mV, whereas the zeta potential in the CMP polishing liquids 1 to 12 and 14 to 17 was -20 mV or less.

[Evaluation of polishing characteristics]
(Fabrication of blanket substrate)
The following substrate was cleaved into small pieces of 20 mm×20 mm and used for the following polishing.
Ruthenium blanket substrate: A silicon substrate having a ruthenium film (thickness: about 90Å) formed by the CVD method.

(Substrate polishing process)
The blanket substrate was chemically mechanically polished for 60 seconds under the following polishing conditions using the CMP polishing liquid.

{Polishing conditions}
Polishing device: Nano Factor Co., Ltd., trade name: FACT-200
Abrasive cloth: Rohm and Haas Electronic Materials CMP, trade name: VP-3200
Plate rotation speed: 80 min ^-1
Polishing pressure: 10 kPa
Supply rate of polishing liquid: 8mL/min

(Evaluation of ruthenium polishing rate)
The polishing rate of the ruthenium blanket substrate polished under the above conditions was determined from the difference in the thickness of the ruthenium film before and after polishing. The film thickness of the ruthenium film was calculated by converting the sheet resistance value obtained using a 4-probe resistance measuring device. The results are shown in Tables 1 to 3.

As in the examples shown in Tables 1 to 3, the polishing liquid for CMP contains a metal oxidant having a redox potential accompanied by the transfer of hydroxide ions, and the redox potential of the standard hydrogen electrode at the redox potential is reduced. The potential is 0.68 V or more, the pH of the polishing liquid for CMP is 7.0 to 13.0, and the content of the abrasive grains is 100 parts by mass in total of the content of the abrasive grains and the content of the water. On the other hand, when it is 0.10 parts by mass or more, it can be seen that a high polishing rate (5 Å/min or more) of ruthenium polishing rate is obtained.

On the other hand, as shown in Table 3, in the comparative example, the ruthenium polishing rate was less than 5Å/min, and it was found that it was not suitable as a CMP polishing liquid for polishing a ruthenium-based metal.

According to the present invention, a high polishing rate of a barrier metal used for a barrier layer can be realized in a wiring forming process of a semiconductor device.

DESCRIPTION OF SYMBOLS 1... Insulating material, 2... Groove part (concave part), 3... Wiring metal, 4... Barrier metal, 5,15... Seed layer, 6... Metal (barrier metal or seed layer), 7... Hole (void), 11... Interlayer insulating film, 12... First barrier layer, 13... Second barrier layer, 14... Conductive material layer.

Claims (14)

A polishing liquid for CMP for polishing a ruthenium-based metal,
Contains abrasive grains, a metal oxidizer, and water,
The metal oxidant has a redox potential accompanied by the transfer of hydroxide ions,
The redox potential is 0.68 V or more with respect to a standard hydrogen electrode,
The pH of the polishing liquid for CMP is 7.0 to 13.0,
The polishing liquid for CMP, wherein the content of the abrasive grains is 0.10 parts by mass or more based on 100 parts by mass of the total content of the abrasive grains and the content of the water. The polishing liquid for CMP according to claim 1, wherein the redox potential is 0.68 to 0.90 V with respect to a standard hydrogen electrode. The polishing liquid for CMP according to claim 1 or 2, wherein the ruthenium-based metal contains at least one selected from the group consisting of ruthenium, ruthenium alloys, and ruthenium compounds. 2. The metal oxidant contains at least one selected from the group consisting of hypochlorous acid, chlorous acid, hypobromic acid, orthoperiodic acid, xenonic acid, perxenonic acid and salts thereof. The polishing liquid for CMP according to any one of items 1 to 3. The metal oxidant contains at least one selected from the group consisting of sodium hypochlorite, calcium hypochlorite, sodium zincate and calcium zincate, according to any one of claims 1 to 4. The polishing liquid for CMP described. The polishing liquid for CMP according to claim 1, further comprising a metal oxide dissolving agent. The polishing liquid for CMP according to claim 6, wherein the metal oxide dissolving agent contains an organic acid. The polishing liquid for CMP according to claim 1, further comprising a metal anticorrosive agent. The metal corrosion inhibitor comprises at least one selected from the group consisting of a compound having an imidazole skeleton, a compound having a triazole skeleton, a compound having a tetrazole skeleton, a compound having a pyrazole skeleton, and a compound having a pyrimidine skeleton. Item 9. A polishing liquid for CMP according to Item 8. The polishing liquid for CMP according to any one of claims 1 to 9, further containing an organic solvent. A substrate having an interlayer insulating material having a ridge and a groove on the surface, a barrier metal provided so as to follow the surface of the interlayer insulating material, and a conductive substance provided so as to cover the barrier metal. Polishing the conductive material to expose the barrier metal located on the ridges of the interlayer insulating material.
A second method for polishing the barrier metal exposed in the first polishing step to expose the raised portion of the interlayer insulating material using the polishing liquid for CMP according to claim 1. And a polishing step. The polishing method according to claim 11, wherein the interlayer insulating material contains at least one selected from the group consisting of silicon compounds and organic polymers. The polishing method according to claim 11 or 12, wherein the conductive substance contains at least one selected from the group consisting of copper, copper alloys, copper oxides, and copper alloy oxides. The polishing method according to any one of claims 11 to 13, wherein the barrier metal contains at least one selected from the group consisting of ruthenium, ruthenium alloys, and ruthenium compounds.

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