KR20130121721A - Slurry, polishing liquid set, polishing liquid, method for polishing substrate, and substrate - Google Patents

Abstract

Polishing liquids according to the embodiment of the present invention comprises an oxidizing agent, an additive (wherein, the oxidizing agent is excluded), abrasive grains and water. The abrasive grains contain the hydroxides of tetravalent metal elements and satisfy at least one condition among a condition providing the absorbance of more than 1.00 based on the light with a wavelength of 400 nm in an aqueous dispersion solution in which the content of the abrasive grains is 1.0 weight% and a condition providing the absorbance of more than 1.000 based on the light with a wavelength of 290 nm in an aqueous dispersion solution in which the content of the abrasive grains is 0.0065 weight%.

Description

Slurry, polishing liquid set, polishing liquid, gas polishing method and gas {SLURRY, POLISHING LIQUID SET, POLISHING LIQUID, METHOD FOR POLISHING SUBSTRATE, AND SUBSTRATE}

The present invention relates to a slurry, a polishing liquid set, a polishing liquid, a method for polishing a substrate, and a substrate. In particular, the present invention relates to a slurry, a polishing liquid set, a polishing liquid, a method for polishing a substrate, and a substrate used in a semiconductor device manufacturing process.

In the recent manufacturing process of semiconductor devices, the importance of processing technology for higher density and miniaturization is increasing. CMP (Chemical Mechanical Polishing) technology, which is one of the processing techniques, forms and freezes the formation of shallow trench isolation (hereinafter, sometimes referred to as "STI") in the semiconductor device manufacturing process. Background Art It has become an essential technique for planarization of metal insulating materials or interlayer insulating materials, and formation of plugs or embedded metal wiring.

Conventionally, in order to planarize an insulating material such as silicon oxide formed by a method such as CVD (Chemical Vapor Deposition) method or rotation coating method in the manufacturing process of a semiconductor device, a fumed silica-based polishing liquid is generally used. It is used in CMP. The fumed silica-based polishing liquid is produced by grain growth of grains by a method such as thermal decomposition of silicon tetrachloride and pH adjustment. However, there is a technical problem that such a silica-based polishing liquid has a low polishing rate.

However, STI is used for device isolation in an integrated circuit in a generation rule of 0.25 mu m or less after the design rule. In STI formation, CMP is used to remove excess portions of insulating material deposited on the substrate. Then, in order to stop polishing in CMP, a slow polishing speed stopper (polishing stop layer) is formed under the insulating material. Silicon nitride, polysilicon, or the like is used as the stopper material (constituent material of the stopper), and it is preferable that the polishing selectivity (polishing rate ratio: polishing rate of insulating material / polishing rate of stopper material) of the insulating material to the stopper material is large. . Silica-based polishing liquids such as conventional colloidal silica-based polishing liquids tend to have a characteristic that the polishing selectivity of the insulating material to the stopper material is about 3, so that the STI has no practical endurance for practical use.

Conventionally, cerium oxide-based polishing liquids containing cerium oxide particles have been used as abrasive grains. The cerium oxide polishing liquid has an advantage that the polishing rate is faster than that of the silica-based polishing liquid containing silica particles as the abrasive grains and the alumina-based polishing liquid containing alumina particles as the abrasive grains. Moreover, recently, the polishing liquid for semiconductors which used the cerium oxide particle of high purity as a cerium oxide type polishing liquid is used (for example, refer following patent document 1).

By the way, in recent years, further refinement | miniaturization of wiring is calculated | required in the manufacturing process of a semiconductor element, and the polishing scratch which arises at the time of grinding | polishing becomes a problem. In other words, when polishing was performed using a conventional cerium oxide-based polishing liquid, even if minute polishing scratches were generated, it would not be a problem if the size of the polishing scratches was smaller than the conventional wiring width. If you want to achieve it becomes a problem.

In response to this problem, attempts have been made to reduce the average particle diameter of cerium oxide particles in the cerium oxide polishing liquid as described above. However, when the average particle diameter is reduced, there is a problem that the polishing rate is lowered because the mechanical action is lowered. Thus, even if it is intended to achieve both the polishing rate and the polishing scratches by controlling the average particle diameter of the cerium oxide particles, it is not difficult to achieve the recent stringent demand for polishing scratches while maintaining the polishing rate.

On the other hand, the polishing liquid using the particle | grains of the hydroxide of a tetravalent metal element is examined (for example, refer patent document 2 below). Moreover, the manufacturing method of the particle | grains of the hydroxide of a tetravalent metal element is also examined (for example, refer following patent document 3). These techniques aim to reduce the polishing scratches caused by the particles by minimizing the mechanical action while utilizing the chemical action of the particles of the hydroxide of the tetravalent metal element.

Japanese Patent Application Laid-Open No. 10-106994 International Publication No. 02/067309 Japanese Patent Laid-Open No. 2006-249129

The present inventors have found that in a polishing liquid using particles containing a hydroxide of a tetravalent metal element and a slurry for obtaining the polishing liquid, ions may be released from the particles over time. As the ions are released from the particles in this manner, ions that are not necessary for polishing may be mixed in the polishing liquid or slurry, or the abrasive grains may be changed to cause variations in polishing characteristics.

Further, immediately before polishing, a slurry containing abrasive grains and an additive liquid containing an additive are mixed to obtain a polishing liquid, and polishing may be performed using the polishing liquid. At this time, the conductivity of the polishing liquid after mixing may be measured as a method for continuously and simply checking whether each liquid is mixed at a predetermined blending ratio. This method is based on the premise that the conductivity of each liquid is not constant or changed substantially. However, if the conductivity of the slurry itself fluctuates because of the release of ions from the particles as described above, such management becomes impossible, so that the process management becomes difficult.

The present invention aims to solve the above problems, and an object of the present invention is to provide a slurry having less ions released over time than in the prior art. Moreover, an object of this invention is to provide the slurry which can obtain the polishing liquid which can grind | polish a to-be-polished material with the outstanding polishing rate.

Further, an object of the present invention is to provide a polishing liquid set and a polishing liquid which can reduce the amount of ions released over time as compared with the conventional one, and can polish the material to be polished at an excellent polishing rate.

In addition, an object of the present invention is to provide a polishing method using the slurry, the polishing liquid set or the polishing liquid, and a substrate obtained thereby.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining about the slurry which used the abrasive containing the hydroxide of a tetravalent metal element, it contains the abrasive and oxidizing agent which have high light absorption (absorbance) with respect to the light of a specific wavelength in the aqueous dispersion containing a specific amount of abrasive. In the slurry described above, it was found that less ions were released over time. In addition, the inventors found that by using such a slurry containing abrasive grains and oxidizing agents, it is possible to polish the to-be-polished material at a low polishing rate and with less ions released over time. In addition, the present inventors have found that when the polishing liquid obtained by adding an additive to such a slurry is used, the material to be polished can be polished at a low polishing rate with less ions released over time.

That is, the 1st Embodiment of the slurry which concerns on this invention contains an oxidizing agent, an abrasive grain, and water, The said abrasive grain contains the hydroxide of a tetravalent metal element, In the aqueous dispersion which adjusted content of the said abrasive grain to 1.0 mass%, An absorbance of 1.00 or more is provided for light having a wavelength of 400 nm.

In the slurry according to the first embodiment, the amount of ions released over time is smaller than in the past, and the change in the content of ions in the slurry is suppressed (for example, the change over time of the conductivity of the slurry is suppressed). The stability is excellent. Therefore, even when two or more types of liquids are mixed, management of the polishing liquid supplying step is easy.

Further, according to the slurry according to the first embodiment, it is possible to obtain a polishing liquid capable of polishing the material to be polished at an excellent polishing rate by the abrasive containing a hydroxide of a tetravalent metal element and providing a predetermined absorbance. In such a polishing liquid, the material to be polished can be polished at an excellent polishing rate while maintaining the effect of adding the additive. Moreover, according to the slurry which concerns on 1st embodiment, a to-be-polished material can be grind | polished at the outstanding grinding | polishing speed. Moreover, according to the slurry which concerns on 1st embodiment, generation | occurrence | production of the polishing flaw on the to-be-polished surface can be suppressed.

In the slurry according to the first embodiment, the abrasive may provide absorbance 1.00 or more and less than 1.50 with respect to light having a wavelength of 400 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 1.0 mass%. Thereby, there exists a tendency for the balance of the stability of an abrasive grain and the polishing rate of a to-be-polished material to be excellent in a slurry.

Moreover, in the slurry which concerns on 1st Embodiment, an abrasive grain may provide an absorbance 1.50 or more with respect to the light of wavelength 400nm in the aqueous dispersion which adjusted the content of the abrasive grain to 1.0 mass%. This tends to be excellent in the polishing rate of the to-be-polished material in a slurry.

In the slurry according to the first embodiment, the abrasive grains preferably provide an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 0.0065 mass% (65 ppm). In this case, the to-be-polished material can be polished at a polishing rate superior to that of the conventional polishing liquid. In addition, "ppm" shall mean mass ppm, ie, "parts per million mass."

The second embodiment of the slurry according to the present invention contains an oxidizing agent, abrasive grains, and water, and the abrasive grains contain a hydroxide of a tetravalent metal element, and the content of the abrasive grains is adjusted to 0.0065% by mass to a wavelength of 290 nm. It is to provide an absorbance of 1.000 or more with respect to light.

In the slurry according to the second embodiment, the amount of ions released over time is smaller than in the past, and the change in the content of ions in the slurry is suppressed (for example, the change over time of the conductivity of the slurry is suppressed). The stability is excellent. Therefore, even when two or more types of liquids are mixed, management of the polishing liquid supplying step is easy.

Further, according to the slurry according to the second embodiment, it is possible to obtain a polishing liquid capable of polishing the polishing material at an excellent polishing rate by providing the abrasive with a hydroxide of tetravalent metal element and providing a predetermined absorbance. In such a polishing liquid, the material to be polished can be polished at an excellent polishing rate while maintaining the effect of adding the additive. Moreover, according to the slurry which concerns on 2nd Embodiment, a to-be-polished material can be grind | polished at the outstanding grinding | polishing speed. Moreover, according to the slurry which concerns on 2nd Embodiment, generation | occurrence | production of grinding | polishing scratches on a to-be-polished surface can be suppressed.

In the slurry according to the present invention, the oxidizing agent is preferably at least one selected from the group consisting of hydrogen peroxide and persulfate. Thereby, the change of content of the ion in a slurry (for example, the time-dependent change of the electrical conductivity of a slurry) can be suppressed further.

In the slurry according to the present invention, it is preferable that the abrasive grains provide an absorbance of 0.010 or less with respect to light having a wavelength of 450 to 600 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 0.0065 mass%. In this case, the to-be-polished material can be polished at a higher polishing rate than in the prior art.

As a result of more intensive investigations on the slurry using the abrasive containing the hydroxide of the tetravalent metal element, the present inventors found that when the abrasive having high absorbance for light of a specific wavelength can increase the light transmittance for light having a wavelength of 500 nm. It has been found that the polishing material can be polished at a better polishing rate. That is, in the slurry according to the present invention, it is preferable that the abrasive grains provide a light transmittance of 50% / cm or more to light having a wavelength of 500 nm in an aqueous dispersion in which the content of the abrasive grains is adjusted to 1.0 mass%.

It is preferable that the hydroxide of a tetravalent metal element is obtained by making a salt of a tetravalent metal element react with an alkali source. In this case, particles having extremely fine particle diameters can be obtained as abrasive grains, so that the effect of reducing polishing scratches can be further improved.

The tetravalent metal element is preferably tetravalent cerium (tetravalent cerium). In this case, since fine particles with high chemical activity are obtained, the to-be-polished material can be polished at a polishing rate superior to the conventional one.

The hydroxide of a tetravalent metal element may contain the nitrate ion couple | bonded with the tetravalent metal element.

In the polishing liquid set according to the present invention, the constituent components of the polishing liquid are preserved by dividing the first liquid and the second liquid into a polishing liquid by mixing the first liquid and the second liquid, and the first liquid is the slurry. The second liquid contains an additive (except the oxidant) and water. According to the polishing liquid set according to the present invention, the amount of ions released over time can be reduced as compared with the conventional one, and the polishing material can be polished at an excellent polishing rate. Further, according to the polishing liquid set according to the present invention, the to-be-polished material can be polished at an excellent polishing rate while maintaining the effect of adding the additive. Further, according to the polishing liquid set of the present invention, the occurrence of polishing scratches can be suppressed.

A first embodiment of a polishing liquid according to the present invention contains an oxidizing agent, an additive (except for the oxidizing agent), abrasive grains, and water, and the abrasive grains contain a hydroxide of a tetravalent metal element, and the content of the abrasive grains is increased. Absorption of 1.00 or more is provided with respect to the light of wavelength 400nm in the aqueous dispersion adjusted to 1.0 mass%.

In the polishing liquid according to the first embodiment, the amount of ions released over time is less than in the past, and the change in the content of ions in the polishing liquid is suppressed (for example, the change over time of the conductivity of the polishing liquid is suppressed. Because of this, the abrasive is stable. Therefore, management of a polishing liquid supply process is easy.

Further, according to the polishing liquid according to the first embodiment, the abrasive is composed of a hydroxide of a tetravalent metal element, and the predetermined absorbance can be provided, whereby the polishing material can be polished at an excellent polishing rate while maintaining the effect of adding the additive. . Moreover, according to the polishing liquid which concerns on 1st Embodiment, generation | occurrence | production of polishing scratches on a to-be-polished surface can also be suppressed.

In the polishing liquid according to the first embodiment, the abrasive grains may provide absorbance 1.00 or more and less than 1.50 to light having a wavelength of 400 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 1.0 mass%. Thereby, there exists a tendency for the balance of the stability of an abrasive grain and the polishing rate of a to-be-polished material to be excellent.

In addition, in the polishing liquid according to the first embodiment, the abrasive grains may provide an absorbance of 1.50 or more to light having a wavelength of 400 nm in an aqueous dispersion in which the content of the abrasive grains is adjusted to 1.0 mass%. Thereby, there exists a tendency for the polishing rate of a to-be-polished material to be excellent in a polishing liquid.

In the polishing liquid according to the first embodiment, it is preferable that the abrasive grains provide an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 0.0065 mass% (65 ppm). In this case, the to-be-polished material can be polished at a higher polishing rate than in the prior art.

A second embodiment of the polishing liquid according to the present invention contains an oxidizing agent, an additive (except for the oxidizing agent), an abrasive, and water, and the abrasive contains a hydroxide of a tetravalent metal element, and the content of the abrasive is The absorbance 1.000 or more is provided with respect to the light of wavelength 290nm in the aqueous dispersion adjusted to 0.0065 mass%.

In the polishing liquid according to the second embodiment, the amount of ions released over time is less than in the past, and the change in the content of ions in the polishing liquid is suppressed (for example, the change over time of the conductivity of the polishing liquid is suppressed. Because of this, the abrasive is stable. Therefore, management of a polishing liquid supply process is easy.

Further, according to the polishing liquid according to the second embodiment, since the abrasive grains contain a hydroxide of a tetravalent metal element and provide a predetermined absorbance, the polishing material can be polished at an excellent polishing rate while maintaining the effect of adding the additive. . Moreover, according to the polishing liquid which concerns on 2nd Embodiment, generation | occurrence | production of polishing scratches on a to-be-polished surface can also be suppressed.

In the polishing liquid of the present invention, the oxidizing agent is preferably at least one selected from the group consisting of hydrogen peroxide and persulfate. Thereby, the change of the content of ions in the polishing liquid (for example, the change over time of the conductivity of the polishing liquid) can be further suppressed.

In the polishing liquid according to the present invention, it is preferable that the abrasive grains provide an absorbance of 0.010 or less with respect to light having a wavelength of 450 to 600 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 0.0065 mass%. In this case, the to-be-polished material can be polished at a higher polishing rate than in the prior art.

In the polishing liquid of the present invention, it is preferable that the abrasive grains provide a light transmittance of 50% / cm or more with respect to light having a wavelength of 500 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 1.0 mass%. In this case, the to-be-polished material can be polished at a higher polishing rate than in the prior art.

In the polishing liquid of the present invention, the hydroxide of the tetravalent metal element is preferably obtained by reacting a salt of the tetravalent metal element with an alkali source. In this case, particles having extremely fine particle diameters can be obtained as abrasive grains, so that the effect of reducing polishing scratches can be further improved.

In the polishing liquid according to the present invention, the tetravalent metal element is preferably tetravalent cerium. In this case, since fine particles with high chemical activity are obtained, the to-be-polished material can be polished at a polishing rate superior to the conventional one.

In the polishing liquid of the present invention, the hydroxide of the tetravalent metal element may contain nitrate ions bonded to the tetravalent metal element.

The present invention provides a method for polishing a substrate using the slurry, the polishing liquid set or the polishing liquid. According to these polishing methods, the material to be polished can be polished at an excellent polishing rate. In addition, according to these polishing methods, generation of polishing scratches can be suppressed, and a base having excellent flatness can also be obtained.

1st Embodiment of the grinding | polishing method which concerns on this invention relates to the grinding | polishing method using the said slurry. That is, the polishing method according to the first embodiment includes the steps of preparing a substrate having a to-be-polished material on the surface, arranging the substrate so that the to-be-polished material faces the polishing pad, and between the polishing pad and the to-be-polished material. And supplying the slurry to polish at least a part of the material to be polished.

2nd and 3rd embodiment of the grinding | polishing method which concerns on this invention relates to the grinding | polishing method using the said grinding | polishing liquid set. According to this polishing method, problems such as agglomeration of abrasive grains, changes in polishing characteristics, etc., which are concerned when stored for a long time after mixing the additives, can be avoided.

That is, the polishing method according to the second embodiment includes the steps of preparing a substrate having a to-be-polished material on the surface, arranging the substrate so that the to-be-polished material faces the polishing pad, and a first in the polishing liquid set. And a step of mixing the liquid and the second liquid to obtain a polishing liquid, and supplying the polishing liquid between the polishing pad and the material to be polished to polish at least a part of the material to be polished. The polishing method according to the third embodiment includes the steps of preparing a substrate having a to-be-polished material on its surface, arranging the substrate so that the to-be-polished material faces the polishing pad, and a first liquid in the polishing liquid set; And a second liquid is supplied between the polishing pad and the material to be polished, respectively, to at least a part of the material to be polished.

A fourth embodiment of the polishing method according to the present invention relates to a polishing method using the polishing liquid. That is, the polishing method according to the fourth embodiment includes the steps of preparing a substrate having a to-be-polished material on the surface, arranging the base so that the to-be-polished material faces the polishing pad, and between the polishing pad and the to-be-polished material. And supplying the polishing liquid to polish at least a part of the material to be polished.

The material to be polished preferably contains silicon oxide. In addition, the surface of the material to be polished preferably has irregularities. According to these polishing methods, the characteristics of the slurry, the polishing liquid set and the polishing liquid can be fully utilized.

The base according to the present invention is polished by the polishing method.

In the slurry according to the present invention, the amount of ions released over time is smaller than in the prior art, and since the change in the content of ions in the slurry is suppressed, the stability of the abrasive is excellent. Therefore, even when two or more types of liquids are mixed, management of the polishing liquid supplying step is easy. Further, according to the slurry according to the present invention, it is possible to obtain a polishing liquid capable of polishing the material to be polished at an excellent polishing rate, and in such a polishing liquid, the polishing material can be polished at an excellent polishing rate while maintaining the effect of adding an additive. Can be. According to the slurry according to the present invention, the material to be polished can be polished at an excellent polishing rate.

In the polishing liquid set and the polishing liquid according to the present invention, ions released over time are smaller than in the prior art, and since the change in the content of ions in the polishing liquid is suppressed, the abrasive is excellent in stability. Therefore, management of a polishing liquid supply process is easy. Further, according to the polishing liquid set and the polishing liquid of the present invention, the material to be polished can be polished at an excellent polishing rate. Further, according to the polishing liquid set and the polishing liquid according to the present invention, the material to be polished can be polished at an excellent polishing rate while maintaining the effect of adding the additive.

Since the polishing method according to the present invention can polish the to-be-polished material at an excellent polishing rate, it is excellent in throughput and can satisfy desired characteristics (for example, flatness and polishing selectivity) when the additive is used.

Further, according to the present invention, the application of the slurry, the polishing liquid set and the polishing liquid to the planarization of the substrate surface in the manufacturing process of the semiconductor element is provided. In particular, the present invention provides the application of the slurry, polishing liquid set and polishing liquid to a planarization process of an STI insulating material, a premetal insulating material, an interlayer insulating material, and the like.

1 is a schematic diagram showing how the abrasive grains aggregate when an additive is added.
2 is a schematic diagram showing how the abrasive grains aggregate when an additive is added.

Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can variously deform and implement within the range of the summary. In this specification, "slurry" and "polishing liquid" are compositions which contact a to-be-polished material at the time of grinding | polishing, and contain water and an abrasive grain at least. In addition, the "water dispersion" which adjusted content of an abrasive grain to predetermined amount means the liquid containing a predetermined amount of abrasive grain and water.

In this embodiment, by using together an abrasive and an oxidizing agent which contain the hydroxide of a tetravalent metal element, and satisfy | fills at least one condition of the following (a) and (b), the ion discharge | released over time compared with the past At the same time, the stability of the abrasive grains can be improved, and the polishing material can be polished at an excellent polishing rate.

(a) The abrasive provides 1.00 or more of absorbance with respect to the light of wavelength 400nm in the aqueous dispersion which adjusted the content of the abrasive grain to 1.0 mass%.

(b) The abrasive provides 1.000 or more of absorbance with respect to the light of wavelength 290nm in the aqueous dispersion which adjusted the content of the abrasive grain to 0.0065 mass%.

The reason why the above effects are obtained is not necessarily clear, but the present inventor thinks as follows. That is, it is thought that the compound which contains a trivalent metal element as a part of an abrasive grain may be produced at the time of manufacture of the abrasive grain which satisfy | fills at least one condition of said (a) and (b). In contrast, the oxidizing agent oxidizes the trivalent metal element contained in the abrasive grain to a tetravalent metal element, thereby increasing the bonding strength between the metal element and the atom, molecule, or molecular group bonded to the metal element, thereby improving the stability and polishing characteristics of the abrasive grain. It is assumed that stability is improved.

<Polishing liquid>

The polishing liquid according to the present embodiment contains at least an abrasive grain, an oxidizing agent, an additive (except for the oxidizing agent), and water. Hereinafter, each component is demonstrated.

(Grip)

The abrasive grains are characterized by containing hydroxides of tetravalent metal elements. "Hydrate of a tetravalent metal element" is a compound containing tetravalent metal ( ^{M4 +} ) and at least 1 hydroxide ion (OH <^-> ) in this specification. The hydroxide of the tetravalent metal element may include anions other than hydroxide ions (for example, nitrate ions NO ₃ ⁻ and sulfate ions SO ₄ ^2- ). For example, the hydroxide of the metal element 4 is a tetravalent anion bound to the metal ^element-may comprise a (for example, nitrate ions NO _3, sulfate SO ₄ ^2-).

The tetravalent metal element is preferably at least one selected from the group consisting of rare earth metal elements and zirconium. As the tetravalent metal element, a rare earth metal element is preferable from the viewpoint of further improving the polishing rate of the insulating material. Examples of the rare earth metal element capable of taking a tetravalent include lanthanoids such as cerium, praseodymium, and terbium, and among them, cerium (tetravalent cerium) is preferable from the viewpoint of easy availability and further improving the polishing rate of the insulating material. . The hydroxide of a rare earth metal element and the hydroxide of zirconium may be used together, and 2 or more types may be selected and used from the hydroxide of a rare earth metal element.

The polishing liquid according to the present embodiment can use other types of abrasive grains in a range that does not impair the characteristics of the abrasive grains containing a hydroxide of a tetravalent metal element. Specifically, abrasive grains such as silica, alumina and zirconia can be used.

As for content of the hydroxide of the tetravalent metal element in an abrasive grain, 50 mass% or more is preferable on the basis of the abrasive grain mass, 60 mass% or more is more preferable, 70 mass% or more is more preferable, 80 mass% or more is especially Preferably, 90 mass% or more is extremely preferable, 95 mass% or more is very preferable, 98 mass% or more is still more preferable, 99 mass% or more is more preferable, and consists substantially of a hydroxide of a tetravalent metal element. It is extremely preferable that substantially 100% by mass of the abrasive grains are hydroxides of a tetravalent metal element.

As for content of the hydroxide of tetravalent cerium in an abrasive grain, 50 mass% or more is preferable on the basis of an abrasive grain mass, 60 mass% or more is more preferable, 70 mass% or more is more preferable, 80 mass% or more is especially preferable. 90 mass% or more is extremely preferable, 95 mass% or more is very preferable, 98 mass% or more is still more preferable, 99 mass% or more is more preferable, in that chemical activity is high and the polishing rate is more excellent More preferably, substantially 100% by mass of the grains of the tetravalent cerium are particles of the hydroxide of the tetravalent cerium.

Among the constituent components of the polishing liquid according to the present embodiment, the hydroxide of the tetravalent metal element is considered to have a large influence on the polishing characteristics. Therefore, by adjusting the hydroxide content of the tetravalent metal element, the chemical interaction between the abrasive grain and the surface to be polished can be improved, and the polishing rate can be further improved. That is, since content of the hydroxide of a tetravalent metal element becomes easy to fully express the function of the hydroxide of a tetravalent metal element, 0.01 mass% or more is preferable on the basis of the total mass of polishing liquid, 0.03 mass% or more is more preferable , 0.05 mass% or more is more preferable. The hydroxide content of the tetravalent metal element makes it easier to avoid agglomeration of the abrasive grains, improves chemical interaction with the surface to be polished, and makes it possible to effectively utilize the characteristics of the abrasive grains. 8 mass% or less is preferable, 5 mass% or less is more preferable, 3 mass% or less is more preferable, 1 mass% or less is especially preferable, 0.5 mass% or less is extremely preferable, and 0.3 mass% or less Very preferred.

In the polishing liquid according to the present embodiment, the lower limit of the content of the abrasive grains is not particularly limited. However, since the desired polishing rate is easy to be obtained, 0.01% by mass or more is preferable on the basis of the total mass of the polishing liquid, and 0.02% by mass or more More preferably, 0.05 mass% or more is more preferable. The upper limit of the abrasive grain content is not particularly limited, but it is easy to avoid agglomeration of the abrasive grains and 10 mass% based on the total mass of the polishing liquid in that the abrasive grains can effectively act on the surface to be polished and smoothly proceed polishing. The following are preferable, 5 mass% or less is more preferable, 3 mass% or less is more preferable, 1 mass% or less is especially preferable, 0.5 mass% or less is extremely preferable, 0.3 mass% or less is very preferable.

If the average secondary particle size of the abrasive grains (hereinafter, referred to as "average particle diameter" unless otherwise specified) is somewhat small, the specific surface area of the abrasive grains in contact with the surface to be polished is increased, and the polishing rate can be further improved. The action can be suppressed to further reduce polishing scratches. For this reason, the upper limit of the average particle diameter is preferably 200 nm or less, more preferably 150 nm or less, still more preferably 100 nm or less, and 80 nm or less, from the viewpoint of achieving a better polishing rate and further reducing polishing scratches. Is especially preferable, 60 nm or less is extremely preferable, and 40 nm or less is very preferable. The lower limit of the average particle diameter is preferably 1 nm or more, more preferably 2 nm or more, and even more preferably 3 nm or more, from the viewpoint that further excellent polishing rate can be obtained and polishing scratches can be further reduced.

The average particle diameter of an abrasive grain can be measured by a photon correlation method, and can be specifically, measured, for example by the apparatus name of a Maruba company: Zetasizer 3000HS, the apparatus name by Beckman Coulter Co., Ltd .: N5, etc. The measuring method using N5 specifically produces the aqueous dispersion which adjusted the content of an abrasive grain to 0.2 mass%, for example, and makes this aqueous dispersion about 4 mL (L is "liter") to the cell of 1 cm square. (Same as below), and a cell is installed in an apparatus. The value obtained by adjusting the refractive index of a dispersion medium to 1.33 and viscosity to 0.887 mPa * s, and measuring at 25 degreeC can be employ | adopted as an average particle diameter of an abrasive grain.

[Absorbance]

An abrasive grain contains the hydroxide of a tetravalent metal element, and satisfy | fills the conditions of at least one of said (a) and (b). Regarding the above condition (a), the polishing rate can be improved by using an abrasive grain that provides an absorbance of 1.00 or more with respect to light having a wavelength of 400 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 1.0 mass%. Although this reason is not necessarily clear, the inventor thinks that it is as follows. That is, M (OH) _a consisting of a tetravalent metal (M ⁴⁺ ), 1 to 3 hydroxide ions (OH ⁻ ) and 1 to 3 anions (X ^{c −} ) depending on the production conditions of the hydroxide of the tetravalent metal element. Particles containing X _b (wherein a + b × c = 4) are considered to be produced as part of the abrasive grains (these particles are also “particles containing hydroxides of tetravalent metal elements”). In M (OH) _a X _b , the electron-absorbing anion (X ^c- ) acts to improve the reactivity of hydroxide ions, and it is thought that the polishing rate increases as the amount of M (OH) _a X _b increases. . Then, the removal rate enhancement in accordance with Since the particles including the M (OH) _a X _b to absorption of light having a wavelength of 400nm, M (OH) increases the amount of presence of _a X _b, the absorbance for a wavelength of 400nm light increases to I think it is.

It is thought that the abrasive containing the hydroxide of a tetravalent metal element can contain not only M (OH) _a X _b but also M (OH) ₄ , MO ₂ , and the like. Examples of the anion (X ^c- ) include NO ₃ ⁻ and SO ₄ ^2- .

In addition, the abrasive containing M (OH) _a X _b is an anion by FT-IR ATR method (Fourier transform Infra Red Spectrometer Attenuated Total Reflection method, Fourier transform infrared spectrophotometer) It can confirm by the method of detecting the peak corresponding to ( ^Xc- ). The presence of anion (X ^c- ) can also be confirmed by XPS method (X-ray Photoelectron Spectroscopy, X-ray photoelectron spectroscopy).

Wherein, M (OH) _a X _b of the absorption peak wavelength of 400nm (for example, M (OH) ₃ X), there is not much smaller than the check absorption peak wavelength of 290nm, which will be described later. On the other hand, the present inventors examined the magnitude of absorbance using an aqueous dispersion having an abrasive grain content of 1.0% by mass, which is relatively high in abrasive grain content, and the absorbance is likely to be largely detected. When using the abrasive grains which provide the following, it was found that the effect of improving the polishing rate is excellent. In addition, since the absorbance with respect to the light of wavelength 400nm is considered as originating from an abrasive grain as mentioned above, the substance which provides the absorbance with 1.00 or more with respect to the light of wavelength 400nm instead of the abrasive grain which provides absorbance 1.00 or more with respect to the light of wavelength 400nm. It goes without saying that in the polishing liquid containing (for example, a yellow pigment component), the material to be polished cannot be polished at an excellent polishing rate.

The absorbance of light having a wavelength of 400 nm is preferably 1.50 or more, more preferably 1.55 or more, still more preferably 1.60 or more, particularly preferably 1.70 or more, from the viewpoint of being easy to polish the material to be polished at an excellent polishing rate. 1.80 or more are extremely preferred.

On the other hand, when calculating the structural stability of the particles containing a hydroxide of a tetravalent metal element, such as M (OH) _a X _b (for example M (OH) ₃ X), the structure of the particles as the amount of X increases The result is that stability is lowered. In contrast, the inventors have found that both the high polishing rate and the high storage stability can be achieved by adjusting the abundance of the particles including X by using the absorbance for light having a wavelength of 400 nm as an index. In addition, the present inventors use the abrasive which provides absorbance 1.00 or more and less than 1.50 with respect to the light of wavelength 400nm in the aqueous dispersion which adjusted the content of abrasive grain to 1.0 mass%, and is excellent storage stability (for example, maintaining an excellent grinding | polishing rate) , Stability of polishing rate when stored at 60 ° C. for 72 hours) was found to be easily obtained. From this point of view, the absorbance of light having a wavelength of 400 nm is preferably 1.10 or more, more preferably 1.20 or more, still more preferably 1.25 or more, particularly preferably 1.30 or more, and extremely preferably 1.35 or more.

Regarding the above condition (b), the reason why the effect of improving the polishing rate is obtained is not necessarily clear by using abrasive grains that provide an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 0.0065 mass%. However, the inventor thinks as follows. That is, the particles containing M (OH) _a X _b (for example, M (OH) ₃ X) generated according to the production conditions of the hydroxide of the tetravalent metal element, etc., have an absorption peak at a wavelength of 290 nm around, For example, particles composed of Ce ⁴⁺ (OH ⁻ ) ₃ NO ₃ ⁻ have an absorption peak at a wavelength of 290 nm. Therefore, it is thought that the polishing rate improves as the abundance of M (OH) _a X _b increases and the absorbance for light having a wavelength of 290 nm increases. On the other hand, when the structural stability of the particles is calculated, the result is that the structural stability of the particles decreases as the amount of X present increases. From these, the polishing rate can be further improved by adjusting the abundance of the particles containing X by using the absorbance for light having a wavelength of 400 nm as an index with the absorbance for light having a wavelength of 290 nm.

Here, the absorbance with respect to the light having a wavelength of about 290 nm tends to be detected largely as the measurement limit is exceeded. On the other hand, the inventors of the present invention examined the magnitude of absorbance using an aqueous dispersion having an abrasive content of 0.0065% by mass and relatively low in absorbance and having a small absorbance. As a result, the absorbance with respect to light having a wavelength of 290 nm in the aqueous dispersion was 1.000. When using the abrasive grain which provides the above, it discovered that the improvement effect of a polishing speed was excellent. In addition, the inventors of the present invention also found that the higher the absorbance of abrasive grains to light near wavelength 290nm, the higher the absorbance of the abrasive to the light near wavelength 290nm, when the absorbent material is absorbed by the light absorbing substance. It was found that the yellowishness of was increased, and the polishing rate was improved as the yellowishness of the polishing liquid and the slurry became darker. And the present inventor discovered that the absorbance with respect to the light of wavelength 290nm in the aqueous dispersion of abrasive grain content 0.0065 mass% correlated with the light with the wavelength of 400 nm in the aqueous dispersion of abrasive grain content 1.0 mass%.

The lower limit of the absorbance to light having a wavelength of 290 nm is preferably 1.000 or more, more preferably 1.050 or more, still more preferably 1.100 or more, particularly preferably 1.150 or more from the viewpoint of polishing the material to be polished at a superior polishing rate. , 1.200 or more are extremely preferred. Although the upper limit of the absorbance with respect to the light of wavelength 290nm does not have a restriction | limiting in particular, For example, 10.00 is preferable, 5.00 or less are more preferable, and 3.00 or less are still more preferable.

When the abrasive which provides an absorbance of 1.00 or more with respect to light having a wavelength of 400 nm provides an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the content of the abrasive grains is adjusted to 0.0065 mass%, The abrasive material can be polished.

A hydroxide of a tetravalent metal element (for example, M (OH) _a X _b ) tends not to have absorbance with respect to light having a wavelength of 450 nm or more, in particular, having a wavelength of 450 to 600 nm. Therefore, from the viewpoint of suppressing adverse effects on polishing by including impurities and polishing the material to be polished at a superior polishing rate, the abrasive grains have a wavelength of 450 in an aqueous dispersion in which the abrasive grain content is adjusted to 0.0065 mass% (65 ppm). It is preferable to provide absorbance 0.010 or less with respect to the light of -600 nm. That is, it is preferable that the absorbance with respect to all the light in the range of 450-600 nm of wavelengths in the aqueous dispersion which adjusted the content of abrasive grain to 0.0065 mass% does not exceed 0.010. The upper limit of the absorbance for light having a wavelength of 450 to 600 nm is more preferably 0.005 or less, and still more preferably 0.001 or less. As for the minimum of the absorbance with respect to the light of wavelength 450-600 nm, 0 is preferable.

The absorbance in the aqueous dispersion can be measured, for example, using a spectrophotometer (device name: U3310) manufactured by Hitachi Seisakusho Co., Ltd. Specifically, the aqueous dispersion which adjusted content of an abrasive grain to 1.0 mass% or 0.0065 mass%, for example is manufactured as a measurement sample. About 4 mL of this measurement sample is put into a 1 cm square cell, and a cell is installed in an apparatus. Next, absorbance measurement is performed in the range of 200-600 nm of wavelengths, and the absorbance is judged from the obtained chart.

In the case where the absorbance is excessively diluted so that the content of the abrasive grain is less than 1.0% by mass and the absorbance for light having a wavelength of 400 nm is measured, the absorbance is 1.00 or more even when the content of the abrasive grain is 1.0% by mass. Absorbance may be screened as. In the case where the absorbance is excessively diluted so that the content of the abrasive grain is less than 0.0065 mass% and the absorbance for light having a wavelength of 290 nm is measured, the absorbance is 1.000 or more even when the content of the abrasive grain is 0.0065 mass%. Absorbance may be screened as. In the case where the absorbance to the light having a wavelength of 450 to 600 nm is measured by diluting the content of the abrasive grain to be greater than 0.0065 mass%, and the absorbance indicates 0.010 or less, the absorbance is 0.010 or less even when the abrasive content is 0.0065 mass%. Absorbance may be screened as.

[Light transmittance]

It is preferable that the polishing liquid according to the present embodiment has high transparency to visible light (visually transparent or close to transparent). Specifically, it is preferable that the abrasive grains contained in the polishing liquid according to the present embodiment provide a light transmittance of 50% / cm or more with respect to light having a wavelength of 500 nm in an aqueous dispersion in which the content of the abrasive grains is adjusted to 1.0 mass%. . Thereby, since the fall of the polishing rate resulting from addition of an additive can further be suppressed, it becomes easy to acquire another characteristic, maintaining a polishing rate. From this point of view, the lower limit of the light transmittance is more preferably at least 60% / cm, still more preferably at least 70% / cm, particularly preferably at least 80% / cm, extremely preferably at least 90% / cm, 95 % / Cm or more is very preferable, 98% / cm or more is further more preferable, 99% / cm or more is more preferable. The upper limit of the light transmittance is 100% / cm.

The reason why the reduction of the polishing rate can be suppressed by adjusting the light transmittance of the abrasive grains is not described in detail, but the present inventor considers as follows. It is thought that chemical action is more dominant than the mechanical action in the action as an abrasive grain which the abrasive containing a tetravalent metal element (cerium etc.) has. Therefore, it is thought that the number of abrasive grains contributes more to a grinding | polishing rate than the magnitude | size of an abrasive grain.

When light transmittance is low in the aqueous dispersion whose content of an abrasive grain is 1.0 mass%, it is thought that the abrasive grain which exists in the aqueous dispersion contains relatively large particle | grains (henceforth "coarse particle"). When an additive (for example, polyvinyl alcohol (PVA)) is added to the polishing liquid containing such abrasive grains, other particles agglomerate as coarse particles as nuclei as shown in FIG. As a result, it is considered that the number of abrasive grains (effective number of abrasive grains) acting on the surface to be polished per unit area decreases and the specific surface area of the abrasive grains in contact with the surface to be polished decreases.

On the other hand, when light transmittance is high in the aqueous dispersion whose content of an abrasive grain is 1.0 mass%, it is thought that the abrasive grain which exists in the aqueous dispersion is a state with few said "coarse particles." In this case, when the amount of coarse particles is small, as shown in Fig. 2, even when an additive (for example, polyvinyl alcohol) is added to the polishing liquid, there are few coarse particles that become nuclei of aggregation, so that agglomeration between the abrasive grains is reduced. It is suppressed or the size of agglomerated particle becomes small compared with the agglomerated particle shown in FIG. As a result, since the abrasive grain number (effective abrasive grain number) which acts on a to-be-polished surface per unit area is maintained, and the specific surface area of the abrasive grain which contacts the to-be-polished surface is maintained, it is thought that the fall of a grinding | polishing rate becomes difficult to occur.

In the examination of the present inventors, it was found that even a polishing liquid having the same particle size measured in a general particle size measuring device may be visually transparent (high light transmittance) and visually cloudy (low light transmittance). From this, it is thought that the coarse particle which can produce the above-mentioned effect contributes to the fall of a grinding | polishing rate even if it is the extremely small amount which cannot be detected by a general particle diameter measuring apparatus.

In addition, even if the filtration is repeated a plurality of times in order to reduce coarse particles, the phenomenon that the polishing rate is lowered by the additive is not so much improved, and it is understood that the effect of improving the polishing rate due to the absorbance may not be sufficiently exhibited. there was. Therefore, the inventors of the present invention have devised a manufacturing method of abrasive grains, and found that the problem can be solved by using abrasive grains having a high light transmittance in an aqueous dispersion.

The light transmittance is a transmittance for light having a wavelength of 500 nm. The light transmittance can be measured by a spectrophotometer. Specifically, it can measure with the spectrophotometer U3310 (device name) by the Hitachi Seisakusho Co., Ltd., for example.

As a more specific measuring method, the aqueous dispersion which adjusted content of abrasive grain to 1.0 mass% is manufactured as a measurement sample. About 4 mL of this measurement sample is put into a 1-cm square cell, a cell is set in an apparatus, and a measurement is performed. It is also clear that in the case of an aqueous dispersion having an abrasive grain content of more than 1.0% by mass, a light transmittance of 50% / cm or more, the light transmittance is 50% / cm or more even when it is diluted to 1.0% by mass. Therefore, by using an aqueous dispersion having a content of abrasive grains larger than 1.0% by mass, the light transmittance can be screened by a simple method.

The absorbance and light transmittance that the abrasive grains contained in the polishing liquid provide in the aqueous dispersion are obtained by removing the solid component other than the abrasive grain and the liquid component other than water, and then preparing an aqueous dispersion having a predetermined abrasive grain content and using the aqueous dispersion. It can be measured. Although different depending on the components contained in the polishing liquid, for example, centrifugal separation using a centrifuge to which gravity acceleration of thousands of G or less is applied, ultracentrifugation to which gravity acceleration of tens of thousands of G or more is applied to the removal of the solid or liquid components. Centrifugal separation methods such as ultracentrifugation using; Chromatographic methods such as partition chromatography, adsorption chromatography, gel permeation chromatography, and ion exchange chromatography; Filtration methods such as natural filtration, reduced pressure filtration, pressure filtration and ultrafiltration; Distillation methods, such as distillation under reduced pressure and atmospheric distillation, can be used, and these can also be combined suitably.

For example, when a weight average molecular weight contains the compound of tens of thousands or more (for example, 50,000 or more), the chromatography method, the filtration method, etc. are mentioned, Especially gel permeation chromatography and ultrafiltration are preferable. In the case of using the filtration method, the abrasive grains contained in the polishing liquid can pass through the filter by setting appropriate conditions. When a weight average molecular weight contains a compound of tens of thousands or less (for example, less than 50,000), a chromatography method, a filtration method, a distillation method, etc. are mentioned, A gel permeation chromatography, an ultrafiltration, and vacuum distillation are preferable. Filtration, centrifugal separation, etc. are mentioned when a plurality of types of abrasive grains are included, and in the case of filtration, more abrasive grains containing the hydroxide of a tetravalent metal element are contained in a filtrate and a liquid phase in the case of centrifugation.

As a method of separating abrasive grains by the said chromatographic method, an abrasive grain component can be fractionated and / or other components can be fractionated under the following conditions, for example.

Sample solution: 100 μL of polishing liquid

A detector: UV-VIS detector made by Hitachi Seisakusho, a brand name "L-4200", Wavelength: 400nm

Integrator: GPC Integrator manufactured by Hitachi Seisakusho, trade name `` D-2500 ''

A pump: The Hitachi Seisakusho make, brand name `` L-7100 ''

Column: Filling column for water-based HPLC by Hitachi Kasei Co., Ltd., trade name "GL-W550S"

Eluent: deionized water

Measuring temperature: 23 ° C

Flow rate: 1 mL / min (pressure is about 40-50 kg / cm ² )

Measurement time: 60 minutes

In addition, it is preferable to perform a degassing treatment of the eluent using a degassing apparatus before performing chromatography. When the degassing apparatus cannot be used, it is preferable to degas the eluent with ultrasonic waves or the like beforehand.

Depending on the components contained in the polishing liquid, there is a possibility that the abrasive grains cannot be fractionated even under the above conditions. In this case, it can be separated by optimizing the sample solution amount, column type, eluent type, measurement temperature, flow rate and the like. In addition, by adjusting the pH of the polishing liquid, it is possible to adjust the outflow time of components contained in the polishing liquid to separate the abrasive grains. When there is an insoluble component in the polishing liquid, it is preferable to remove the insoluble component by filtration, centrifugation or the like as necessary.

[Manufacturing method of abrasive grain]

The hydroxide of a tetravalent metal element can be produced by making a salt (metal salt) of a tetravalent metal element react with an alkali source (base). It is preferable that the hydroxide of a tetravalent metal element is produced by mixing the salt of a tetravalent metal element and alkaline liquid (for example, aqueous alkali solution). Thereby, the particle | grains whose particle diameter is very fine can be obtained, and the polishing liquid which is more excellent in the effect of reducing a polishing scratch can be obtained. Such a method is disclosed by patent document 3, for example. The hydroxide of a tetravalent metal element can be obtained by mixing the metal salt solution (for example, metal salt aqueous solution) and alkali liquid of the salt of a tetravalent metal element. In addition, when supplying at least one of the salt and the alkali source of a tetravalent metal element to a reaction system in a liquid state, the means for stirring a mixed liquid is not limited. For example, the method of stirring a liquid mixture using the stirrer or stirring blade of the rod shape, plate shape, or propeller rotating around a rotating shaft; A method of stirring a mixed liquid by rotating a stirrer in a rotating magnetic field using a magnetic stir bar that transmits power from the outside of the container; A method of stirring the mixed liquid with a pump installed outside the tank; And a method of stirring the mixed liquid by pressurizing the outside air and blowing it into the tank. As the salt of the tetravalent metal element, when the metal is represented as M, M (NO ₃ ) ₄ , M (SO ₄ ) ₂ , M (NH ₄ ) ₂ (NO ₃ ) ₆ , M (NH ₄ ) ₄ (SO ₄ ) ₄ Etc. can be mentioned.

As a means of adjusting absorbance and light transmittance, optimization of the manufacturing method of the hydroxide of a tetravalent metal element, etc. are mentioned. As a method of changing the absorbance with respect to the light of wavelength 400nm, and the absorbance with respect to the light of wavelength 290nm, specifically, for example, selection of the alkali source in an alkali liquid, adjustment of the raw material concentration in a metal salt solution and an alkali liquid, a metal salt solution, Adjustment of the mixing speed of an alkali liquid and adjustment of the liquid temperature of the liquid mixture obtained by mixing the salt of an tetravalent metal element and an alkali source are mentioned. As a method of changing the light transmittance with respect to the light of wavelength 500nm, specifically, for example, adjustment of the raw material concentration in a metal salt solution and an alkaline liquid, adjustment of the mixing rate of a metal salt solution and an alkaline liquid, and a stirring speed at the time of mixing Adjustment and adjustment of the liquid temperature of a liquid mixture are mentioned.

In order to improve the absorbance with respect to the light of wavelength 400nm, the absorbance with respect to the light of wavelength 290nm, and the light transmittance with respect to the light of wavelength 500nm, it is preferable to make the manufacturing method of the hydroxide of a tetravalent metal element more "soft". Here, "slow" means that the pH rises slowly when the pH of the reaction system increases (slow) as the reaction proceeds. On the contrary, in order to lower the absorbance with respect to the light of wavelength 400nm, the absorbance with respect to the light of wavelength 290nm, and the light transmittance with respect to the light of wavelength 500nm, it is preferable to make the manufacturing method of the hydroxide of a tetravalent metal element more "violent". . Here, "violent" means that the increase in pH when the pH of the reaction system rises (faster) as the reaction proceeds. In order to adjust the values of absorbance and light transmittance in a predetermined range, it is preferable to refer to the above trends and to optimize the production method of the hydroxide of the tetravalent metal element. Hereinafter, the control method of absorbance and light transmittance is demonstrated in more detail.

{Alkalione}

Although there is no restriction | limiting in particular as an alkali source of alkaline liquid, An organic base, an inorganic base, etc. are mentioned. As an organic base, Nitrogen containing organic bases, such as guanidine, triethylamine, and chitosan; Nitrogen-containing heterocyclic organic bases such as pyridine, piperidine, pyrrolidine and imidazole; Ammonium salts, such as ammonium carbonate, ammonium hydrogen carbonate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium chloride, and tetraethylammonium chloride, etc. are mentioned. Examples of the inorganic base include inorganic salts of alkali metals such as ammonia, lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate. An alkali source can be used individually by 1 type or in combination of 2 or more types.

In order to raise the absorbance with respect to the light of wavelength 400nm, and the absorbance with respect to the light of wavelength 290nm, it is preferable to use the alkali source which shows weak basicity as an alkali source. Among the alkali sources, a nitrogen-containing heterocyclic organic base is preferable, pyridine, piperidine, pyrrolidine and imidazole are more preferable, pyridine and imidazole are more preferable, and imidazole is particularly preferable.

{density}

By controlling the concentration of the raw materials in the metal salt solution and the alkaline liquid, the absorbance for light having a wavelength of 400 nm, the absorbance for light having a wavelength of 290 nm, and the light transmittance for light having a wavelength of 500 nm can be changed. Specifically, the absorbance tends to be increased by increasing the metal salt concentration of the metal salt solution, and the absorbance tends to be increased by decreasing the alkali concentration (base concentration, alkali source concentration) of the alkaline liquid. The light transmittance tends to be increased by increasing the metal salt concentration, and the light transmittance tends to be increased by decreasing the alkali concentration.

The upper limit of the metal salt concentration in the metal salt solution is preferably 1.000 mol / L or less, more preferably 0.500 mol / L or less, based on the whole of the metal salt solution, in that it is easy to achieve both excellent polishing speed and excellent abrasive stability. And, 0.300 mol / L or less is more preferable, 0.200 mol / L or less is especially preferable. The lower limit of the metal salt concentration can suppress the rapid occurrence of the reaction (which can moderately increase the pH), and absorbance for light having a wavelength of 400 nm, absorbance for light having a wavelength of 290 nm, and wavelength 500 nm. Since the light transmittance with respect to the light becomes high, 0.010 mol / L or more is preferable based on the whole metal salt solution, 0.020 mol / L or more is more preferable, 0.030 mol / L or more is more preferable.

The upper limit of the alkali concentration in the alkaline liquid is preferably 15.0 mol / L or less, more preferably 12.0 mol / L or less, more preferably 10.0 mol, based on the total amount of the alkaline liquid in view of suppressing the rapid occurrence of the reaction. / L or less is more preferable, and 5.0 mol / L or less is especially preferable. The lower limit of the alkali concentration is not particularly limited, but is preferably 0.001 mol / L or more based on the whole of the alkali liquid from the viewpoint of productivity.

The alkali concentration in the alkaline liquid is preferably adjusted appropriately by the alkali source selected. For example, in the case of an alkali source whose pKa of the conjugate acid of the alkali source is 20 or more, the upper limit of the alkali concentration is 0.10 mol / L or less based on the whole of the alkali liquid in that the reaction is suppressed from occurring suddenly. It is preferable, 0.05 mol / L or less is more preferable, 0.01 mol / L or less is more preferable. The lower limit of the alkali concentration is not particularly limited, but is preferably 0.001 mol / L or more based on the whole of the alkali liquid in terms of suppressing the amount of the solution used to obtain a predetermined amount of the tetravalent metal element hydroxide.

In the case of an alkali source having a pKa of the conjugate acid of the alkali source of 12 or more and less than 20, the upper limit of the alkali concentration is preferably 1.0 mol / L or less based on the whole of the alkali liquid in that the reaction is suppressed from occurring rapidly. , 0.50 mol / L or less is more preferable, and 0.10 mol / L or less is more preferable. The lower limit of the alkali concentration is not particularly limited, but is preferably 0.01 mol / L or more based on the total amount of the alkaline liquid in terms of suppressing the amount of the solution used for obtaining a predetermined amount of the tetravalent metal element hydroxide.

In the case of an alkali source having a pKa of the conjugate acid of the alkali source of less than 12, the upper limit of the alkali concentration is preferably 15.0 mol / L or less based on the whole of the alkali liquid in that the reaction is suppressed from occurring rapidly, and 10.0 mol / L or less is more preferable, and 5.0 mol / L or less is more preferable. Although the minimum of alkali concentration is not specifically limited, 0.10 mol / L or more is preferable based on the whole alkali liquid from the point which suppresses the usage-amount of the solution used in order to obtain the hydroxide of a predetermined amount of tetravalent metal elements.

As a specific alkali source, as an alkali source whose pKa of the conjugate acid of an alkali source is 20 or more, 1,8- diazabicyclo [5.4.0] undeca-7-ene (pKa: 25) is mentioned, for example. . As an alkali source whose pKa of the conjugate acid of an alkali source is 12 or more and less than 20, potassium hydroxide (pKa: 16) and sodium hydroxide (pKa: 13) are mentioned, for example. As an alkali source whose pKa of the conjugate acid of an alkali source is less than 12, ammonia (pKa: 9) and imidazole (pKa: 7) are mentioned, for example. The pKa value of the conjugate acid of the alkali source to be used is not particularly limited as long as the alkali concentration is properly adjusted, but the pKa of the conjugate acid of the alkali source is preferably less than 20, more preferably less than 12, and even more preferably less than 10. It is especially preferable that it is less than 8.

{Mix speed}

By controlling the mixing rate of the metal salt solution and the alkaline liquid, the absorbance for light with a wavelength of 400 nm, the absorbance for light with a wavelength of 290 nm, and the light transmittance for light with a wavelength of 500 nm can be changed. As a tendency, the absorbance and the light transmittance are respectively increased by making the rise of pH slow (slow). More specifically, the absorbance tends to be increased by slowing the mixing rate, and the absorbance tends to be lowered by increasing the mixing rate. By slowing the mixing speed, the light transmittance for light having a wavelength of 500 nm tends to increase, and the light transmittance tends to be lowered by increasing the mixing speed.

The upper limit of the mixing speed is preferably 5.00 × 10 ⁻³ m ³ / min (5 L / min) or less from the viewpoint of further suppressing the rapid progress of the reaction and further suppressing the bias of the local reaction. 1.00 x 10 ^-3 m ³ / min (1 L / min) or less is more preferable, 5.00 x 10 ^-4 m ³ / min (500 mL / min) or less is more preferable, and 1.00 x 10 ^-4 m ³ / min ( 100 mL / min) or less is particularly preferable. The lower limit of the mixing speed is not particularly limited, but is preferably 1.00 × 10 ⁻⁷ m ^{3 /} min (0.1 mL / min) or more from the viewpoint of productivity.

{Stirring speed}

The light transmittance with respect to the light of wavelength 500nm can be changed by control of the stirring speed at the time of mixing a metal salt solution and alkaline liquid. Specifically, the light transmittance tends to be increased by increasing the stirring speed, and the light transmittance tends to be decreased by slowing the stirring speed.

The lower limit of the stirring speed will, to further suppress the uneven distribution of the reaction at the local, in which at least 30min ^-1 excellent mixing efficiency point of view it is preferred, and, over 50min ^-1 and more preferably more preferably at least 80min ^-1 . The upper limit of the stirring speed is not particularly limited, and an appropriate adjustment is required depending on the size and shape of the stirring blade. From the viewpoint of suppressing liquid splashing, 1000 min ⁻¹ or less is preferable.

{Liquid temperature (synthesis temperature)}

By controlling the liquid temperature of the mixed liquid obtained by mixing a salt of a tetravalent metal element and an alkali source, it is possible to change the absorbance for light with a wavelength of 400 nm, the absorbance for light with a wavelength of 290 nm, and the light transmittance for light with a wavelength of 500 nm. In addition, it is possible to obtain abrasive grains which can achieve a desired polishing rate and storage stability. Specifically, the absorbance tends to be increased by lowering the liquid temperature, and the absorbance tends to be lowered by increasing the liquid temperature. The light transmittance tends to be increased by lowering the liquid temperature, and the light transmittance tends to be lowered by increasing the liquid temperature.

The liquid temperature is, for example, a temperature in the mixed liquid which can be read by installing a thermometer in the mixed liquid, and is preferably 0 to 100 ° C. The upper limit of the liquid temperature is preferably 100 ° C. or less, more preferably 60 ° C. or less, still more preferably 55 ° C. or less, even more preferably 50 ° C. or less, particularly preferably 45 ° C. or less, from the point that the rapid reaction can be suppressed. Extremely preferred. As for the minimum of liquid temperature, 0 degreeC or more is preferable at the point which can advance reaction easily, 10 degreeC or more is more preferable, and 20 degreeC or more is more preferable.

Although the hydroxide of the tetravalent metal element produced by the above may contain an impurity, you may remove the said impurity. Although the method of removing an impurity is not specifically limited, For example, methods, such as centrifugation, a filter press, and ultrafiltration, are mentioned. Thereby, the absorbance with respect to the light of wavelength 450-600 nm can be adjusted.

(Oxidizing agent)

The polishing liquid according to the present embodiment contains an oxidizing agent. From the viewpoint of further improving the stability of the abrasive, the content of the oxidizing agent is preferably 0.10 mmol / L or more, more preferably 0.15 mmol / L or more, and even more preferably 0.20 mmol / L or more. The content of the oxidant is preferably 1 mol / L or less, more preferably 100 mmol / L or less, even more preferably 20 mmol / L or less from the viewpoint of suppressing aggregation of the abrasive grains.

Examples of the oxidizing agent include hydrogen peroxide, persulfate, periodate, hypochlorous acid, and ozone water. Among them, at least one selected from the group consisting of hydrogen peroxide and persulfate is preferable. Examples of the persulfate include ammonium persulfate, potassium persulfate, sodium persulfate, and the like. Among them, ammonium persulfate is preferable. Examples of the periodic acid salt include potassium periodate and the like.

(additive)

Since the polishing liquid according to the present embodiment can obtain a particularly excellent polishing rate with respect to the inorganic insulating material (for example, silicon oxide), the polishing liquid is particularly suitable for use for polishing a substrate having an inorganic insulating material. According to the polishing liquid of the present embodiment, by appropriately selecting an additive, polishing characteristics other than the polishing rate and the polishing rate can be highly compatible.

As an additive, for example, a dispersant which increases the dispersibility of abrasive grains, a polishing rate improving agent which improves the polishing rate, a leveling agent (a leveling agent which reduces the irregularities of the surface to be polished after polishing, and a global leveling agent which improves the global flatness of the substrate after polishing) ), And well-known additives, such as a selectivity improving agent which improves the polishing selectivity of an inorganic insulating material with respect to stopper materials, such as a silicon nitride or polysilicon, can be used without a restriction | limiting in particular. The additive is different from the oxidant.

As a dispersing agent, a vinyl alcohol polymer and its derivative (s), betaine, lauryl betaine, and lauryl dimethylamine oxide are mentioned, for example. Examples of the polishing rate enhancer include β-alanine betaine and stearyl betaine. As a leveling agent which reduces the unevenness | corrugation of a to-be-polished surface, ammonium lauryl sulfate and a polyoxyethylene alkyl ether triethanolamine are mentioned, for example. Examples of the global planarizing agent include polyvinylpyrrolidone and polyacrolein. Examples of the selectivity improving agent include polyethyleneimine, polyallylamine, and chitosan. These can be used individually by 1 type or in combination of 2 or more types.

It is preferable that the polishing liquid which concerns on this embodiment contains at least 1 sort (s) chosen from the group which consists of a vinyl alcohol polymer and its derivative (s) as an additive. In this case, since the additives cover the abrasive grain surface, the adhesion of the abrasive grains to the surface to be polished is suppressed, so that the dispersibility of the abrasive grains can be improved and the stability of the abrasive grains can be further improved. Moreover, the washability of the to-be-polished surface can also be improved. However, vinyl alcohol, which is generally a monomer of polyvinyl alcohol, tends not to exist as a stable compound alone. Therefore, polyvinyl alcohol is obtained by generally polymerizing carboxylic acid vinyl monomers, such as a vinyl acetate monomer, and obtaining polycarboxylic acid, and then saponifying this (hydrolysis). Thus, for example, a vinyl alcohol polymer obtained by using a vinyl acetate monomer as a raw material may have an -OCOCH ₃ and hydrolyzed -OH group as the functional group in the molecule, and is defined as the ratio is -OH as a saponification degree. That is, the vinyl alcohol polymer having a saponification degree of not 100% has substantially the same structure as a copolymer of vinyl acetate and vinyl alcohol. In addition, the vinyl alcohol polymer copolymerizes carboxylic acid vinyl monomers, such as a vinyl acetate monomer, and another vinyl group containing monomer (for example, ethylene, propylene, styrene, and vinyl chloride), and is derived from a carboxylic acid vinyl monomer. All or part of may be saponified. In this specification, these are collectively defined as "vinyl alcohol polymer", but "vinyl alcohol polymer" is ideally a polymer having the following structural formula.

(Wherein n represents a positive integer)

The "derivative" of a vinyl alcohol polymer is a derivative of a homopolymer of vinyl alcohol (i.e., a polymer having a saponification degree of 100%), and the air of a vinyl alcohol monomer and another vinyl group-containing monomer (e.g., ethylene, propylene, styrene, vinyl chloride). It is defined as including derivatives of coalescing.

As a derivative of a vinyl alcohol polymer, the thing which substituted some hydroxyl groups of a polymer with an amino group, a carboxyl group, ester group, etc., and the thing which modified | denatured some hydroxyl groups of a polymer are mentioned, for example. As such a derivative, for example, reactive polyvinyl alcohol (e.g., Nippon Kosei Chemical Co., Ltd., Kosepime (registered trademark) Z), cationic polyvinyl alcohol (e.g., Nippon Kosei Chemical Co., Ltd.) Kaku Kogyo Co., Ltd., Kosepimer (registered trademark) K), Anionized polyvinyl alcohol (e.g., Nippon Kosei Kagaku Kogyo Co., Ltd.), Koseran (registered trademark) L, Kosenal (registered trademark T) and a hydrophilic group modified polyvinyl alcohol (For example, Nippon Kosei Chemical Co., Ltd. make, Ecomati).

As described above, the vinyl alcohol polymer and its derivatives function as a dispersant for abrasive grains, and thus have an effect of further improving the stability of the polishing liquid. The hydroxyl group of the vinyl alcohol polymer and its derivatives interacts with the abrasive grains containing the hydroxide of a tetravalent metal element, thereby suppressing the aggregation of the abrasive grains and suppressing the change of the grain size of the abrasive grains in the polishing liquid, thereby improving the stability. do.

The vinyl alcohol polymer and its derivatives are used in combination with abrasive grains containing hydroxides of tetravalent metal elements, thereby providing a polishing selectivity for inorganic insulating materials (e.g. silicon oxide) relative to stopper materials (e.g. silicon nitride, polysilicon). (The polishing rate of an inorganic insulating material / the polishing rate of a stopper material) can also be made high. In addition, the vinyl alcohol polymer and its derivatives can improve the flatness of the polished surface after polishing, and can also prevent the adhesion of abrasive grains to the polished surface (improving the cleanability).

As for the saponification degree of a vinyl alcohol polymer and its derivative, 95 mol% or less is preferable at the point which the polishing selectivity of an inorganic insulating material with respect to a stopper material becomes further high. From the same viewpoint, the upper limit of the degree of saponification is more preferably 90 mol% or less, still more preferably 88 mol% or less, particularly preferably 85 mol% or less, extremely preferably 83 mol% or less, and even more preferably 80 mol% or less.

Although there is no restriction | limiting in particular in the minimum of saponification degree, From a viewpoint which is excellent in the solubility in water, 50 mol% or more is preferable, 60 mol% or more is more preferable, 70 mol% or more is more preferable. The degree of saponification of the vinyl alcohol polymer and derivatives thereof can be measured in accordance with JIS K 6726 (polyvinyl alcohol test method).

The upper limit of the average degree of polymerization (weight average molecular weight) of the vinyl alcohol polymer and its derivatives is not particularly limited, but is preferably 3000 or less, more preferably 2000 or less, and more preferably 1000 from the viewpoint of further suppressing a decrease in the polishing rate of the material to be polished. The following is more preferable.

From the viewpoint of further increasing the polishing selectivity of the inorganic insulating material to the stopper material, the lower limit of the average degree of polymerization is preferably 50 or more, more preferably 100 or more, and still more preferably 150 or more. The average degree of polymerization of the vinyl alcohol polymer and derivatives thereof can be measured in accordance with JIS K 6726 (polyvinyl alcohol test method).

As a vinyl alcohol polymer and its derivative (s), in order to adjust the polishing selectivity of the inorganic insulating material with respect to a stopper material, and the flatness of the gas after grinding | polishing, you may use combining several polymer from which a degree of saponification, average polymerization degree, etc. differs. In this case, the saponification degree of at least one vinyl alcohol polymer and derivatives thereof is preferably 95 mol% or less, and from the viewpoint of further improving the polishing selectivity, the average saponification degree calculated from each saponification degree and compounding ratio is 95 mol% or less. More preferred. The preferable range of the degree of saponification is the same as the above range.

From the viewpoint of the effect of the additive being more effectively obtained, the content of the additive is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1.0% by mass or more. In addition, the content of the additive is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more preferably 3.0% by mass or less on the basis of the total mass of the polishing liquid, from the viewpoint of further suppressing a decrease in the polishing rate of the material to be polished. desirable.

(water)

The water in the polishing liquid of the present embodiment is not particularly limited, but deionized water, ultrapure water, or the like is preferable. The content of water may be the remainder of the polishing liquid excluding the content of other constituent components, and is not particularly limited.

Although there is no restriction | limiting in particular as a method of disperse | distributing an abrasive grain in water, Specifically, For example, the dispersion method by stirring; Dispersion methods by a homogenizer, an ultrasonic disperser, a wet ball mill, etc. are mentioned.

[Characteristics of Polishing Liquid]

As for pH (25 degreeC) of polishing liquid, 2.0-9.0 are preferable at the point which the further excellent polishing rate is obtained. This is considered to be because the surface potential of the abrasive grains with respect to the surface potential of the polished surface becomes good, and the abrasive grains are more likely to act on the polished surface. Since pH of a polishing liquid is stabilized and it becomes difficult to produce problems, such as aggregation of an abrasive grain (for example, aggregation of a pH stabilizer), the lower limit of pH is preferably 2.0 or more, more preferably 4.0 or more, 5.0 The above is more preferable. Since the dispersibility of an abrasive grain is excellent and a further excellent polishing rate is obtained, 9.0 or less are preferable, as for the upper limit of pH, 8.0 or less are more preferable, and 7.5 or less are still more preferable.

The pH of the polishing liquid can be measured with a pH meter (for example, model number PH81 manufactured by Yokogawa Electric KK). As pH, for example, two-point calibration is performed using a standard buffer solution (phthalate pH buffer: pH 4.01 (25 ° C), neutral phosphate pH buffer: pH6.86 (25 ° C)), and then the electrode is placed in the polishing liquid. A value after 2 minutes or more has passed and stabilized is adopted.

A conventionally well-known pH adjuster can be used for adjustment of pH of polishing liquid without a restriction | limiting in particular. As a pH adjuster, For example, Inorganic acids, such as phosphoric acid, a sulfuric acid, nitric acid; Organic acids such as formic acid, acetic acid, propionic acid, maleic acid, phthalic acid, citric acid, succinic acid, malonic acid, glutaric acid, adipic acid, fumaric acid, lactic acid, benzoic acid and the like; Amines such as ethylenediamine, toluidine, piperazine, histidine, aniline, 2-aminopyridine, 3-aminopyridine, picolinic acid, morpholine, piperidine and hydroxylamine; And nitrogen-containing heterocyclic compounds such as pyridine, imidazole, triazole, pyrazole, benzoimidazole and benzotriazole. In addition, a pH adjuster may be contained in the slurry (to include slurry precursor, the stock solution for slurry, etc.), addition liquid, etc. which are mentioned later.

The pH stabilizer refers to an additive for adjusting to a predetermined pH, and a buffer component is preferable. The buffering component is preferably a compound having a pKa within. + -. 1.5 with respect to a predetermined pH, and more preferably a compound having a pKa within. + -. 1.0. As such a compound, For example, amino acids, such as glycine, arginine, lysine, asparagine, aspartic acid, glutamic acid; A mixture of said carboxylic acid and base; The salt of the said carboxylic acid is mentioned.

<Slurry>

The slurry according to the present embodiment may be used as it is for polishing, or may be used as a slurry in a so-called two-liquid type polishing solution in which the constituent components of the polishing solution are divided by the slurry and the additive solution. In the present embodiment, the polishing liquid and the slurry are different in the presence or absence of an additive, and the polishing liquid is obtained by adding the additive to the slurry.

The slurry which concerns on this embodiment contains at least the abrasive grains, an oxidizing agent, and water similar to the polishing liquid which concerns on this embodiment. For example, an abrasive grain is characterized by containing a hydroxide of a tetravalent metal element, and the preferable range and measuring method of the average secondary particle diameter of an abrasive grain are the same as the abrasive grain used in the polishing liquid which concerns on this embodiment.

In the slurry according to the present embodiment, the abrasive grain satisfies at least one of the above conditions (a) and (b). It is preferable that an abrasive grain provides absorbance 0.010 or less with respect to the light of wavelength 450-600 nm in the aqueous dispersion which adjusted the content of the abrasive grain to 0.0065 mass%. It is preferable that an abrasive grain provides the light transmittance 50% / cm or more with respect to the light of wavelength 500nm in the aqueous dispersion which adjusted the content of the abrasive grain to 1.0 mass%. The preferable ranges and measuring methods of these absorbances and light transmittances are also similar to the abrasive grains used in the polishing liquid according to the present embodiment.

In the constituent components of the slurry according to the present embodiment, the hydroxide of the tetravalent metal element is considered to have a large influence on the polishing characteristics. Therefore, by adjusting the hydroxide content of the tetravalent metal element, the chemical interaction between the abrasive grain and the surface to be polished can be improved, and the polishing rate can be further improved. That is, since content of the hydroxide of a tetravalent metal element becomes easy to fully express the function of the hydroxide of a tetravalent metal element, 0.01 mass% or more is preferable on a slurry total mass basis, 0.03 mass% or more is more preferable, 0.05 mass% or more is more preferable. The content of the hydroxide of the tetravalent metal element is 8 mass based on the total mass of the slurry in that it is easy to avoid agglomeration of the abrasive grains, and the chemical interaction with the surface to be polished is improved to further improve the polishing rate. % Or less is preferable, 5 mass% or less is more preferable, 3 mass% or less is more preferable, 1 mass% or less is especially preferable, 0.5 mass% or less is extremely preferable, 0.3 mass% or less is very preferable. .

In the slurry according to the present embodiment, the lower limit of the content of the abrasive grains is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and 0.05% by mass, based on the total mass of the slurry, in that the desired polishing rate is easily obtained. % Or more is more preferable. Although the upper limit of content of an abrasive grain does not have a restriction | limiting in particular, 10 mass% or less is preferable on the basis of the total mass of a slurry, 5 mass% or less is more preferable, and 3 mass% or less is more preferable from the point which it becomes easy to avoid aggregation of an abrasive grain. 1 mass% or less is especially preferable, 0.5 mass% or less is extremely preferable, and 0.3 mass% or less is very preferable.

The content of the oxidizing agent in the slurry according to the present embodiment is preferably 0.01 mmol / L or more, more preferably 0.05 mmol / L or more, more preferably 0.1 mmol / L or more on the basis of the entire slurry from the viewpoint of further improving the stability of the abrasive grains. This is more preferable. In addition, the content of the oxidant is preferably 20 mmol / L or less, more preferably 10 mmol / L or less, further preferably 5 mmol / L or less based on the total slurry.

PH (25 degreeC) of the slurry which concerns on this embodiment is a point where the surface potential of an abrasive grain with respect to the surface potential of a to-be-polished surface becomes favorable, and since an abrasive grain acts easily with respect to a to-be-polished surface, a superior polishing rate is obtained. 2.0 to 9.0 are preferred. The lower limit of the pH is preferably 2.0 or more, more preferably 2.2 or more, and more preferably 2.5 or more, in that the pH of the slurry becomes stable and problems such as aggregation of the abrasive grains (for example, aggregation by addition of a pH stabilizer) are less likely to occur. This is more preferable. The upper limit of pH is preferably 9.0 or less, more preferably 8.0 or less, still more preferably 7.0 or less, particularly preferably 6.5 or less, particularly preferably 6.0 or less, in view of excellent dispersibility of abrasive grains and obtaining a superior polishing rate. Extremely preferred. PH of a slurry can be measured by the method similar to pH of the polishing liquid which concerns on this embodiment.

<Polishing liquid set>

In the polishing liquid set according to the present embodiment, the constituent components of the polishing liquid are divided into the slurry and the additive liquid and stored so that the slurry (first liquid) and the additive liquid (second liquid) are mixed into the polishing liquid. As the slurry, the slurry according to the present embodiment can be used. As the additive liquid, a liquid obtained by dissolving an additive in water (a liquid containing an additive and water) can be used. The polishing liquid set is used as the polishing liquid by mixing the slurry and the additive liquid at the time of polishing. Thus, by dividing and storing the structural component of polishing liquid into at least 2 liquid, it can be set as the polishing liquid which is more excellent in storage stability. Moreover, in the polishing liquid set which concerns on this embodiment, you may divide a component into three or more liquids.

As the additive contained in the additive liquid, additives similar to those described in the above-mentioned polishing liquid may be used. The content of the additive in the additive liquid is preferably 0.01% by mass or more, based on the total mass of the additive liquid, from the viewpoint of suppressing excessive reduction of the polishing rate when the additive liquid and the slurry are mixed to prepare the abrasive liquid. Mass% or more is more preferable. The content of the additive in the additive liquid is preferably 20% by mass or less on the basis of the total mass of the additive liquid from the viewpoint of suppressing excessive reduction in the polishing rate when the additive liquid and the slurry are mixed to prepare the polishing liquid.

Although there is no restriction | limiting in particular as water in an addition liquid, Deionized water, ultrapure water, etc. are preferable. Content of water may be remainder except content of the other structural component, and is not specifically limited.

<Gas Polishing Method and Gas>

A method for polishing a substrate using the polishing liquid, a slurry or a polishing liquid set, and a substrate obtained thereby will be described. The polishing method according to the present embodiment is a polishing method using a one-liquid type polishing liquid when the polishing liquid or slurry is used, and a two-liquid polishing liquid or a polishing liquid of three or more types when using the polishing liquid set. Polishing method using.

In the substrate polishing method of the present embodiment, a substrate (eg, a semiconductor substrate) having a surface to be polished is polished. In the substrate polishing method of the present embodiment, the material to be polished can be polished using a stopper formed under the material to be polished. The substrate polishing method according to the present embodiment includes at least a preparation step, a gas placement step, and a polishing step. In the preparation step, a gas having a surface to be polished is prepared. In the gas batch process, the base is placed so that the material to be polished faces the polishing pad. In the polishing process, at least a part of the material to be polished is removed using, for example, a polishing liquid, a slurry, or a polishing liquid set. The shape of the to-be-polished material to be polished is not particularly limited, but is, for example, a film (film of the to-be-polished material).

Examples of the material to be polished include inorganic insulating materials such as silicon oxide; And stopper materials such as silicon nitride and polysilicon. Among them, inorganic insulating materials such as silicon oxide are preferred. The silicon oxide film can be obtained by a low pressure CVD method, a plasma CVD method, or the like. The film of silicon oxide may be doped with elements such as phosphorus and boron. As a film of an inorganic insulating material, what is called a film of a low-k material can also be used. It is preferable that unevenness | corrugation is formed in the surface (ground surface) of a to-be-polished material. In the substrate polishing method of the present embodiment, a convex portion of the uneven surface of the material to be polished is preferentially polished to obtain a substrate having a flat surface.

In the case of using a one-liquid type polishing liquid or slurry, at least a part of the polishing material is polished by supplying a polishing liquid or slurry between the substrate to be polished of the substrate and the polishing pad of the polishing platen. For example, the polishing liquid or slurry is supplied between the polishing pad and the polishing material while the polishing material is pressed on the polishing pad to relatively move the substrate and the polishing plate to polish at least a portion of the polishing material. At this time, the polishing liquid and the slurry may be supplied onto the polishing pad as it is as a composition of a desired moisture content.

The polishing liquid and slurry according to the present embodiment are for polishing liquids, which are liquid media such as water and are diluted by two or more times (by mass basis), from the viewpoint of suppressing costs related to storage, transportation, storage, and the like. It can be stored as a stock solution or a stock solution for a slurry. Each of these reservoirs may be diluted with a liquid medium just prior to polishing and may be diluted on the polishing pad by supplying a stock solution and a liquid medium onto the polishing pad.

As the lower limit of the dilution ratio (mass basis) of the stock solution, the higher the magnification ratio is, the higher the inhibitory effect of the costs related to storage, transportation, storage, etc., is preferably two or more times, more preferably three times or more, and five times or more More preferably, 10 times or more is especially preferable. Although there is no restriction | limiting in particular as an upper limit of a dilution magnification, 500 times or less are preferable, and 200 times or less is preferable, since the higher magnification tends to increase the quantity of the component contained in a stock solution (higher concentration) and to lower stability during storage. Is more preferable, 100 times or less is more preferable, and 50 times or less is particularly preferable. The same applies to the polishing liquid obtained by dividing the component by three or more liquids.

Although there is no restriction | limiting in particular in content of an abrasive grain in the said storage liquid, 20 mass% or less is preferable on the basis of the total mass of a storage liquid from the point which it becomes easy to avoid aggregation of an abrasive grain, 15 mass% or less is more preferable, 10 mass % Or less is more preferable, and 5 mass% or less is especially preferable. The content of the abrasive grains is preferably 0.02% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, from the viewpoint of suppressing costs related to storage, transportation, storage, and the like. Mass% or more is especially preferable.

In the case of using a two-liquid type polishing liquid, the substrate polishing method according to the present embodiment may have a polishing liquid manufacturing step of mixing the slurry and the additive liquid to obtain a polishing liquid before the polishing step. In this case, in the polishing step, the material to be polished is polished using the polishing liquid obtained in the polishing liquid manufacturing step. In such a polishing method, the slurry and the additive liquid may be fed into separate pipes in the polishing liquid manufacturing step, and these pipes may be joined immediately before the supply pipe outlet to obtain a polishing liquid. The polishing liquid may be supplied on the polishing pad as it is as a polishing liquid of a desired moisture amount, or may be diluted on the polishing pad after being supplied on the polishing pad as a storage liquid with a small amount of moisture. The same applies to the polishing liquid obtained by dividing the component by three or more liquids.

In the case of using a two-liquid type polishing liquid, in the polishing step, at least a part of the material to be polished is supplied by the polishing liquid obtained by supplying the slurry and the additive liquid between the polishing pad and the to-be-polished material, respectively, and mixing the slurry and the additive liquid. May be polished. In this polishing method, the slurry and the additive liquid can be supplied onto the polishing pad by a separate delivery system. The slurry and / or addition liquid may be supplied on the polishing pad as it is as a liquid of a desired moisture amount, or may be diluted on the polishing pad after being supplied on the polishing pad as a storage liquid with a small amount of moisture. The same applies to the polishing liquid obtained by dividing the component by three or more liquids.

As a polishing apparatus used in the polishing method according to the present embodiment, for example, a holder for holding a substrate having a material to be polished, a motor having a changeable rotation speed, and the like are attached, and have a polishing plate to which the polishing pad can be attached. A general polishing apparatus can be used. As said grinding | polishing apparatus, the grinding | polishing apparatus (model number: EPO-111) by the Ebara Corporation company, the grinding | polishing apparatus (brand name: Mirra3400, Reflexion grinding | polishing machine) by Applied Materials, Inc. are mentioned, for example.

There is no restriction | limiting in particular as a polishing pad, For example, a general nonwoven fabric, foamed polyurethane, and a porous fluororesin can be used. Moreover, it is preferable that the grinding | polishing pad is given the groove processing which a grinding liquid etc. accumulate.

There is no restriction | limiting in particular as grinding | polishing conditions, The low rotation whose rotation speed of a grinding | polishing platen is 200min <^-1> (rpm) or less is preferable from the standpoint which suppresses that a base sticks out. The pressure (processing load) applied to the base is preferably 100 kPa or less in view of further suppressing occurrence of polishing scratches. It is preferable to continuously supply a polishing liquid or slurry to the surface of the polishing pad with a pump or the like while polishing. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with a polishing liquid or a slurry. It is preferable to dry the base body after completion | finish of grinding | cleaning in flowing water, after dropping the water droplet adhered to a base with a spin dryer or the like.

Example

Hereinafter, the present invention will be described concretely with reference to Examples, but the present invention is not limited thereto.

(Production of Slurry Stock)

<Examples 1 to 6, Comparative Example 1>

A hydroxide of a tetravalent metal element was prepared according to the following procedure. Cerium was used as the tetravalent metal element. First, 7603 g of water was put in a container, and an aqueous solution of cerium ammonium nitrate having a concentration of 50% by mass (Chemical Formula Ce (NH ₄ ) ₂ (NO ₃ ) ₆ , foodstuff 548.2 g / mol, manufactured by Nippon Chemical Industries, Ltd.), product name 50 1037 g of% CAN liquid) was added and mixed, and then the liquid temperature was adjusted to 40 ° C to obtain a metal salt aqueous solution.

Next, imidazole was dissolved in water to prepare 4566 g of an aqueous solution with a concentration of 0.7 mol / L, and the liquid temperature was adjusted to 20 to 25 ° C to obtain an alkaline liquid.

The vessel containing the aqueous metal salt solution was placed in a water tank filled with water, and the water temperature of the water tank was adjusted to 40 ° C. using an external circulator Coolix Circulator (EYELA manufactured, product name cooling thermopump CTP101). . While maintaining the water temperature of the aqueous metal salt solution at 40 ° C., while stirring the aqueous metal salt solution at a stirring rate of 400 min ⁻¹ , the alkaline liquid was added into the vessel at a mixing rate of 0.0000085 m ^{3 /} min (8.5 mL / min) to obtain tetravalent cerium. The slurry precursor 1 containing the abrasive grain containing a hydroxide was obtained. The pH of slurry precursor 1 was 2.2. In addition, in the stirring of the metal salt aqueous solution, the three blade | wing pitch puddle of the wing | tip part full length 5cm was used.

The slurry precursor 2 was obtained by ultrafiltration circulating the obtained slurry precursor 1 using the hollow-particle filter of fractional molecular weight 50000. In the ultrafiltration, the ions were removed until the conductivity became 50 mS / m or less. In addition, the said ultrafiltration was performed, adding water so that the water level of the tank containing slurry precursor 1 might be fixed using the liquid level sensor. The content of the abrasive grain in slurry precursor 2 was computed by taking appropriate amount of the obtained slurry precursor 2, and measuring the mass (non-volatile content) before and after drying. In addition, when content of an abrasive grain was less than 1.0 mass% at this stage, it concentrated to the extent exceeding 1.1 mass% by performing ultrafiltration further.

Water was added to the slurry precursor 2, the content of the abrasive grain was adjusted to 1.0 mass%, and the slurry precursor 3 was obtained. By adding the oxidizing agent of Table 1 to slurry precursor 3, the stock solution for slurry which has an oxidizing agent concentration of Table 1, and contains 1.0 mass% of grains was obtained (The change of abrasive grain content can be ignored since the addition amount of oxidizing agent is trace amount. ).

&Lt; Example 7 >

After adding the oxidizing agent to the slurry precursor 3, the stock solution for slurry was obtained by the method similar to Example 5 except having heated at 60 degreeC for 1 week (7 days = 168 hours).

(Structure analysis of the abrasive grain)

An appropriate amount of the stock solution for slurry was collected, vacuum dried to isolate the abrasive grains, and sufficiently washed with pure water. When the obtained sample was measured by the FT-IR ATR method, a peak based on nitrate ions (NO ₃ ⁻ ) was observed in addition to the peak based on hydroxide ions. Further, with respect to the same sample deoni done by XPS (N-XPS) measurements for the nitrogen, a peak based on NH ₄ ⁺ it is a peak was observed based on the nitrate ion is not observed. From these results, it was confirmed that the abrasive grains contained in the stock solution for slurry contains at least part of particles having nitrate ions bonded to the cerium element. Moreover, since at least some abrasive grains contained the particle | grains which have the hydroxide ion couple | bonded with the cerium element, it was confirmed that an abrasive grain contains the hydroxide of cerium. From these results, it was confirmed that the hydroxide of cerium contains the hydroxide ion couple | bonded with the cerium element.

(Measurement of Absorbance and Light Transmittance)

An appropriate amount of the stock solution for slurry was collected, and the oxidizing agent was removed by ultrafiltration and diluted with water so that the abrasive grain content was 0.0065 mass% (65 ppm) to obtain a measurement sample (water dispersion). About 4 mL of this measurement sample was put into 1 cm square cell, and the cell was installed in the spectrophotometer (device name: U3310) by the Hitachi Seisakusho company. The absorbance measurement was performed in the range of 200-600 nm in wavelength, and the absorbance with respect to the light of wavelength 290 nm and the absorbance with respect to the light of wavelength 450-600 nm were measured. The results are shown in Table 1.

In addition, an appropriate amount of the stock solution for slurries was collected, and the oxidizing agent was removed by ultrafiltration, and diluted with water so that the abrasive grain content was 1.0 mass% to obtain a measurement sample (water dispersion). About 4 mL of this measurement sample was put into 1 cm square cell, and the cell was installed in the spectrophotometer (device name: U3310) by the Hitachi Seisakusho company. The absorbance measurement was performed in the range of 200-600 nm in wavelength, and the absorbance with respect to the light of wavelength 400nm and the light transmittance with respect to the light of wavelength 500nm were measured. The results are shown in Table 1.

(Measurement of change in conductivity)

An appropriate amount of the stock solution for slurry was sampled, and measurement sample A was obtained. The measurement sample A was adjusted to 25 degreeC, and electrical conductivity was measured using the electrical conductivity meter (the apparatus name: ES-51) by Horiba Corporation | KK. In addition, measurement sample A was heated at 60 degreeC for 72 hours, and measurement sample B was obtained. Also about the measurement sample B, it adjusted to 25 degreeC and measured electric conductivity similarly. The difference which subtracted the electrical conductivity of the measurement sample A which is not heated from the electrical conductivity of the measurement sample B which heated at 60 degreeC for 72 hours was computed as an electrical conductivity change amount. The results are shown in Table 1.

(Production of polishing liquid)

Pure water was added to 60 g of the slurry storage solution to obtain a slurry. Further, a 5% by mass aqueous polyvinyl alcohol solution was prepared as an additive liquid. After 60 g of the additive solution was added to the slurry, the mixture was stirred and mixed to obtain a polishing liquid having an abrasive grain content of 0.2% by mass, a polyvinyl alcohol content of 1% by mass, and an oxidant content of 0.6 mmol / L. Pure water added to the stock solution for slurry was calculated and added so that final abrasive content might be 0.2 mass%. The saponification degree of polyvinyl alcohol in the polyvinyl alcohol aqueous solution was 80 mol%, and the average polymerization degree was 300. In addition, the pH (25 degreeC) of the slurry and the polishing liquid were measured using model number PH81, manufactured by Yokogawa Denki Co., Ltd., and were 3.6 and 6.0 in all of the examples and the comparative examples. The average particle diameter of the abrasive grains in the polishing liquid was measured using a device name N5 manufactured by Beckman Coulter Co., Ltd., and it was 25 nm in any of the examples and the comparative examples.

(Polishing of insulating material)

A 200 mm-diameter silicon wafer (a silicon wafer blanket wafer) on which a silicon oxide film was formed as an insulating material was placed in a holder affixed with a suction pad for gas attachment in a polishing apparatus. The holder was mounted on the surface plate on which the porous urethane resin pad was affixed so that the insulating material could face the pad. The substrate was pushed onto the pad with a polishing load of 20 kPa while supplying the polishing liquid obtained above to the pad at a feed amount of 200 mL / min. At this time, polishing was performed by rotating the platen at 78 min ⁻¹ and the holder at 98 min ⁻¹ for 1 minute. The polished wafer was thoroughly cleaned with pure water and dried. The polishing rate was determined by measuring the change in film thickness before and after polishing using an optical interference film thickness measuring apparatus. The polishing rates of Example 2, Example 5 and Comparative Example 1 were all 350 kPa / min. In addition, the polishing rate of the other examples was also equivalent (350 + 50 dl / min).

Further, the silicon wafer polished and washed under the above conditions was immersed in an aqueous solution of 0.5% by mass of hydrogen fluoride for 15 seconds and washed with water for 60 seconds. Subsequently, the surface of the insulating material was washed with a polyvinyl alcohol brush while supplying water for 1 minute and then dried. The defect of 0.2 micrometer or more of the surface of an insulating material was detected using the Complus (product name) by Applied Materials. In addition, the surface of the insulating material was observed using the defect detection coordinates obtained from the compass and the SEM Vision manufactured by Applied Materials, and the number of polishing scratches of 0.2 µm or more on the surface of the insulating material was found in Examples 1 to 7 and Comparative Example 1 In any of the above, generation of polishing scratches was sufficiently suppressed to about 0 to 3 (pieces / wafer).

Claims (30)

Contains oxidizing agents, abrasive grains, water,
The slurry wherein the abrasive contains a hydroxide of a tetravalent metal element and provides an absorbance of 1.00 or more with respect to light having a wavelength of 400 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 1.0 mass%. The slurry according to claim 1, wherein the abrasive grains provide absorbance of 1.00 or more and less than 1.50 to light having a wavelength of 400 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 1.0 mass%. The slurry according to claim 1, wherein the abrasive grains provide an absorbance of 1.50 or more with respect to light having a wavelength of 400 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 1.0 mass%. The slurry according to any one of claims 1 to 3, wherein the abrasive grains provide an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the content of the abrasive grains is adjusted to 0.0065% by mass. Contains oxidizing agents, abrasive grains, water,
The slurry wherein the abrasive contains a hydroxide of a tetravalent metal element and provides an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 0.0065 mass%. The slurry according to any one of claims 1 to 5, wherein the oxidant is at least one selected from the group consisting of hydrogen peroxide and persulfate. The slurry according to any one of claims 1 to 6, wherein the abrasive provides an absorbance of 0.010 or less with respect to light having a wavelength of 450 to 600 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 0.0065 mass%. The said abrasive grain provides the light transmittance 50% / cm or more with respect to the light of wavelength 500nm in the aqueous dispersion which adjusted the content of the abrasive grain to 1.0 mass%, Slurry. The slurry according to any one of claims 1 to 8, wherein the hydroxide of the tetravalent metal element is obtained by reacting a salt of the tetravalent metal element with an alkali source. The slurry according to any one of claims 1 to 9, wherein the tetravalent metal element is tetravalent cerium. The slurry according to any one of claims 1 to 10, wherein the hydroxide of the tetravalent metal element contains nitrate ions bonded to the tetravalent metal element. The constituent components of the polishing liquid are preserved by dividing the first liquid and the second liquid into the polishing liquid so that the first liquid and the second liquid are mixed, and the first liquid is any one of claims 1 to 11. The polishing liquid set according to claim 1, wherein the second liquid contains an additive (except for the oxidizing agent) and water. Oxidizing agent, additives (except for the above oxidizing agent), abrasive grains, and water,
The abrasive liquid containing a hydroxide of a tetravalent metal element and providing absorbance 1.00 or more with respect to the light of wavelength 400nm in the aqueous dispersion which adjusted the content of the said abrasive grain to 1.0 mass%. The polishing liquid according to claim 13, wherein the abrasive grains provide an absorbance of 1.00 or more and less than 1.50 to light having a wavelength of 400 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 1.0 mass%. The polishing liquid according to claim 13, wherein the abrasive grains provide an absorbance of 1.50 or more with respect to light having a wavelength of 400 nm in an aqueous dispersion in which the abrasive grain content is adjusted to 1.0 mass%. The polishing liquid according to any one of claims 13 to 15, wherein the abrasive provides an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 0.0065 mass%. Oxidizing agent, additives (except for the above oxidizing agent), abrasive grains, and water,
The abrasive liquid containing the hydroxide of a tetravalent metal element, and providing abrasiveness 1.000 or more with respect to the light of wavelength 290nm in the aqueous dispersion which adjusted the content of the said abrasive grain to 0.0065 mass%. The polishing liquid according to any one of claims 13 to 17, wherein the oxidant is at least one selected from the group consisting of hydrogen peroxide and persulfate. The polishing liquid according to any one of claims 13 to 18, wherein the abrasive provides an absorbance of 0.010 or less with respect to light having a wavelength of 450 to 600 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 0.0065 mass%. . The said abrasive grain provides the light transmittance 50% / cm or more with respect to the light of wavelength 500nm in the aqueous dispersion which adjusted the content of the abrasive grain to 1.0 mass%, Polishing liquid. The polishing liquid according to any one of claims 13 to 20, wherein the hydroxide of the tetravalent metal element is obtained by reacting a salt of the tetravalent metal element with an alkali source. The polishing liquid according to any one of claims 13 to 21, wherein the tetravalent metal element is tetravalent cerium. The polishing liquid according to any one of claims 13 to 22, wherein the hydroxide of the tetravalent metal element contains nitrate ions bonded to the tetravalent metal element. Preparing a gas having a material to be polished on its surface;
Disposing the base such that the abrasive material faces the polishing pad;
A method for polishing a substrate, comprising: supplying the slurry according to any one of claims 1 to 11 between the polishing pad and the to-be-polished material, and polishing at least a part of the to-be-polished material. Preparing a gas having a material to be polished on its surface;
Disposing the base such that the abrasive material faces the polishing pad;
Mixing the first liquid and the second liquid in the polishing liquid set according to claim 12 to obtain the polishing liquid,
And polishing the at least part of the material to be polished by supplying the polishing liquid between the polishing pad and the material to be polished. Preparing a gas having a material to be polished on its surface;
Disposing the base such that the abrasive material faces the polishing pad;
A gas having a step of supplying the first liquid and the second liquid in the polishing liquid set according to claim 12, respectively, between the polishing pad and the to-be-polished material to polish at least a part of the to-be-polished material. Polishing method. Preparing a gas having a material to be polished on its surface;
Disposing the base such that the abrasive material faces the polishing pad;
A method for polishing a substrate having a step of supplying the polishing liquid according to any one of claims 13 to 23 between the polishing pad and the polishing material to polish at least a part of the polishing material. 28. The method of any one of claims 24 to 27, wherein the material to be polished comprises silicon oxide. The method for polishing a substrate according to any one of claims 24 to 28, wherein the surface of the polishing material has irregularities. A base polished by the method for polishing a base according to any one of claims 24 to 29.

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