TW201840805A - Polishing liquid, polishing liquid set, additive liquid, and polishing method - Google Patents

Abstract

A polishing liquid contains abrasive particles, a water-soluble compound containing a trivalent rare earth element, and a liquid medium, and the content of the water-soluble compound exceeds 0% by mass and less than 0.05% by mass.

Description

Polishing liquid, polishing liquid set, additive liquid and polishing method

The invention relates to a polishing liquid, a polishing liquid set, an additive liquid and a polishing method. The present invention particularly relates to a polishing liquid, a polishing liquid set, an additive liquid, and a polishing method that can be used in a planarization step of a substrate surface as a manufacturing technology of a semiconductor element. In more detail, the present invention relates to a method for planarizing a shallow trench isolation (hereinafter referred to as "STI") insulating material, a premetal insulating material, an interlayer insulating material, and the like. Polishing liquid, polishing liquid set, additive liquid and polishing method.

In the manufacturing steps of semiconductor devices in recent years, the importance of processing technology for high density and miniaturization has gradually increased. As one of the processing technologies, Chemical Mechanical Polishing (CMP) technology has been used in the manufacturing steps of semiconductor devices to perform STI formation, planarization of front metal insulating materials or interlayer insulating materials, plugs or buried Required for the formation of metal wiring.

Examples of the most commonly used polishing liquids include silicon dioxide-based polishing liquids containing silicon dioxide (silica) particles such as fumed silica and colloidal silicon dioxide as abrasive particles. The silicon dioxide-based polishing liquid is characterized by high versatility. By appropriately selecting the content of abrasive particles, pH value, additives, etc., it can grind a wide variety of materials regardless of the insulating material and conductive material.

On the other hand, as a polishing liquid mainly targeted for an insulating material such as silicon oxide, the demand for a polishing liquid containing cerium compound particles as abrasive particles has also increased. For example, a cerium oxide-based polishing liquid containing cerium oxide (ceria) particles as abrasive particles can grind silicon oxide at a high speed even if the content of the abrasive particles is lower than that of a silicon dioxide-based polishing liquid (for example, refer to the following patent) Literature 1 and Patent Literature 2). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 10-106994 [Patent Literature 2] Japanese Patent Laid-Open Publication No. 08-022970 [Patent Literature 3] Japanese Patent Publication No. 2001-507739 [Patent Literature 4] International Publication No. 2002/067309 [Patent Literature 5] International Publication No. 2012/070541 [Patent Literature 6] International Publication No. 2012/070542 [Patent Literature 7] Japanese Patent Laid-Open No. 2006-249129 [Patent Literature 8] International Publication No. 2012/070544

[Problems to be Solved by the Invention] In recent years, 3D-transistor (NAND) devices in which a cell portion of a device is stacked in a vertical direction have risen. In the present technology, the step difference of the insulating material at the time of cell formation is several times higher than that of the previous planar type. Along with this, in order to maintain the throughput of device manufacturing, it is necessary to quickly eliminate such a high step in a CMP step or the like, and it is necessary to increase the polishing speed of the insulating material. In addition, it is required to increase the polishing rate of the insulating material by using additives in the polishing liquid.

The present invention is intended to solve the problems, and an object thereof is to provide a polishing liquid which is a polishing liquid containing a water-soluble compound containing a trivalent rare-earth element, and which is similar to the case where a water-soluble compound containing a trivalent rare-earth element is not used. In comparison, the grinding speed of the insulating material can be increased. Another object of the present invention is to provide a polishing liquid set and an additive liquid capable of obtaining the polishing liquid. Furthermore, an object of the present invention is to provide a polishing method using the polishing liquid. [Means for solving problems]

The present inventors have found that when using abrasive particles, a predetermined amount of a water-soluble compound containing a trivalent rare-earth element, and a liquid medium, it appears that the water-soluble compound containing a trivalent rare-earth element does not appear when using abrasive particles. The effect of improving the grinding speed of the insulating material is obtained.

The polishing liquid of the present invention contains abrasive particles, a water-soluble compound containing a trivalent rare earth element, and a liquid medium, and the content of the water-soluble compound exceeds 0% by mass and less than 0.05% by mass.

According to the polishing liquid of the present invention, as compared with a case where a water-soluble compound containing a trivalent rare earth element is not used, the polishing rate of the insulating material can be increased, and the insulating material can be polished at a high polishing rate.

In addition, Patent Document 3 describes that a polishing composition containing a soluble cerium compound is used, and the content of the soluble cerium compound is 0.05 to 10% by weight. On the other hand, according to the polishing liquid of the present invention, when the content of the water-soluble compound containing a trivalent rare earth element is less than 0.05% by mass, the effect of improving the polishing rate can be obtained, and the content of the water-soluble compound is 0.05. Compared with the case of mass% or more, the use amount of the additive can be suppressed, and the effect of improving the polishing rate can be obtained.

In addition, according to the polishing liquid of the present invention, the STI insulating material, the front metal insulating material, the interlayer insulating material, and the like can be used to planarize the insulating materials in the CMP technology.

In addition, as the content of the abrasive grains increases, there is a tendency that abrasive damage tends to occur. On the other hand, according to the polishing liquid of the present invention, a sufficient polishing speed can be obtained even with a small amount of abrasive particles. Therefore, by using a small amount of abrasive particles, a sufficient polishing speed can be achieved and the insulating material can be polished with low polishing damage. .

The content of the abrasive particles is preferably more than 0% by mass and 1.5% by mass or less. Here, in the said patent document 3, content of the abrasive grain (metal oxide abrasive) is 2 weight%-25 weight%. On the other hand, in the polishing liquid of the present invention, compared with the above-mentioned Patent Document 3, even if the content of the abrasive particles is small, the effect of improving the polishing speed can be obtained, and the generation of polishing damage can be further suppressed and the polishing speed can be obtained. Effect.

The abrasive particles preferably include a cerium compound. The cerium compound preferably contains a cerium hydroxide. The cerium compound preferably contains a cerium oxide.

In addition, in recent years, in the manufacturing steps of semiconductor devices, further miniaturization of wiring is required, and polishing damage generated during polishing has become a problem. In other words, even if a small amount of polishing damage occurs during polishing using a conventional cerium oxide-based polishing liquid, as long as the size of the polishing damage is smaller than the previous wiring width, it is not a problem, but it is necessary to achieve finer wiring. In the case of metalization, even abrasion damage is a problem. To solve this problem, a polishing liquid using particles of hydroxides of a tetravalent metal element has been studied (for example, refer to the aforementioned Patent Documents 4 to 6). Moreover, the manufacturing method of the particle | grains of the hydroxide of a tetravalent metal element is also examined (for example, refer the said patent document 7 and patent document 8). These technologies make effective use of the chemical action of the particles of the hydroxide of the tetravalent metal element and minimize the mechanical action, thereby reducing the abrasive damage caused by the particles. From the viewpoint of further suppressing the occurrence of polishing damage in the polishing liquid of the present invention, it is also preferable to use abrasive particles containing a hydroxide of a tetravalent metal element.

The zeta potential of the abrasive particles may be positive or negative. The absolute value of the boundary potential of the abrasive particles is preferably 10 mV or more.

The trivalent rare earth element of the water-soluble compound preferably contains cerium. The water-soluble compound preferably contains at least one selected from the group consisting of cerium nitrate, cerium ammonium nitrate, cerium chloride, cerium phosphate, cerium sulfate, and cerium acetate.

It is preferable that the polishing liquid of this invention does not contain a tetravalent rare-earth element (except the component contained in the said abrasive particle) as an active ingredient.

The content of the oxidant is preferably less than 0.05% by mass.

The pH of the polishing liquid of the present invention is preferably 2.0 to 10.0.

One aspect of the present invention relates to the use of the polishing liquid for polishing a surface to be polished including silicon oxide. That is, the polishing liquid of the present invention is preferably used for polishing a surface to be polished containing silicon oxide.

The polishing liquid kit of the present invention divides and stores the constituent components of the polishing liquid into a first liquid and a second liquid, where the first liquid includes the abrasive particles and a liquid medium, and the second liquid includes The water-soluble compound, and a liquid medium. According to the polishing liquid set of the present invention, the same effects as those of the polishing liquid of the present invention can be obtained.

The additive liquid of the present invention is an additive liquid that is mixed with a liquid containing the abrasive particles to obtain the polishing liquid, and contains the water-soluble compound and a liquid medium. According to the additive liquid of the present invention, the same effects as those of the polishing liquid of the present invention can be obtained.

The polishing method of the present invention may include the step of polishing the surface to be polished using the polishing liquid, and may also include using polishing obtained by mixing the first liquid and the second liquid in the polishing liquid set. Step of polishing the surface to be polished. According to these polishing methods, the same effect as that of the polishing liquid of the present invention can be obtained by using the polishing liquid or the polishing liquid set. [Effect of the invention]

According to the present invention, it is possible to provide a polishing liquid capable of improving the polishing speed of an insulating material (for example, silicon oxide) as compared with a case where a water-soluble compound containing a trivalent rare earth element is not used. The addition effect of a water-soluble compound containing a trivalent rare-earth element can be compared with the grinding speed when a water-soluble compound containing a trivalent rare-earth element is used, and when the water-soluble compound containing a trivalent rare-earth element is not used Confirm the polishing speed. In addition, according to the present invention, it is possible to provide a polishing liquid set and an additive liquid capable of obtaining the polishing liquid. Furthermore, according to the present invention, a polishing method using the polishing liquid can be provided.

According to the present invention, in the CMP technology for planarizing STI insulating materials, front metal insulating materials, interlayer insulating materials, etc., these insulating materials can be highly planarized. In addition, according to the present invention, a sufficient polishing rate can be achieved, and the insulating material can be polished with low polishing damage.

According to the present invention, the use of a polishing liquid, a polishing liquid set, or an additive liquid in a flattening step of a substrate surface can be provided. According to the present invention, the use of a polishing liquid, a polishing liquid set, or an additive liquid for the planarization step of an STI insulating material, a front metal insulating material, or an interlayer insulating material can be provided.

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

<Definition> In this specification, a numerical range expressed using "~" means a range including the numerical value described before and after "~" as the minimum and maximum ranges, respectively. Among the numerical ranges described stepwise in this specification, an upper limit value or a lower limit value of a numerical range at a certain stage may be replaced with an upper limit value or a lower limit value of a numerical range at another stage. In the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples. The term "A or B" may include any one of A and B, or both. Unless otherwise specified, the materials exemplified in this specification may be used alone or in combination of two or more. In the present specification, when a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the plurality of substances present in the composition unless otherwise specified.

In this specification, a "polishing liquid" (abrasive) is defined as a composition which comes into contact with a surface to be polished during polishing. The phrase "polishing liquid" does not in itself limit the ingredients contained in the polishing liquid. As will be described later, the polishing liquid of this embodiment contains abrasive grains. Abrasive particles are also referred to as "abrasive particles", but are referred to as "abrasive particles" in this specification. The abrasive particles are generally considered to be solid particles. During polishing, the removal object is removed by the mechanical action of the abrasive particles and the chemical action of the abrasive particles (mainly the surface of the abrasive particles), but it is not limited to this. this.

<Polishing liquid> The polishing liquid of this embodiment is a polishing liquid for CMP, for example. The polishing liquid of this embodiment contains abrasive particles, a water-soluble compound containing a trivalent rare earth element, and a liquid medium, and the content of the water-soluble compound exceeds 0% by mass and less than 0.05% by mass. The essential components and optional components are described below.

(Abrasive particles) Examples of the metal element constituting the abrasive particles include a rare earth element, silicon, aluminum, and zirconium. Examples of the rare-earth element include lanthanoids such as cerium, and yttrium. The abrasive particles may include an oxide of the metal element, a hydroxide of the metal element, and the like.

From the viewpoint of further improving the polishing rate of the insulating material, the abrasive particles preferably contain a cerium compound. From the viewpoint of further improving the polishing rate of the insulating material, the cerium compound preferably contains at least one selected from the group consisting of cerium oxide and cerium hydroxide. Examples of the cerium oxide include cerium oxide.

From the viewpoint of further improving the polishing rate of the insulating material, the abrasive grains are preferably selected from the group consisting of cerium dioxide, silicon dioxide, aluminum oxide, zirconia, yttrium oxide, and hydroxides of metal elements. It is at least one kind of metal oxide, and more preferably a hydroxide containing a metal element (a tetravalent metal element, etc.).

In the present specification, the "hydroxide of a tetravalent metal element" is a compound containing a tetravalent metal (M ⁴⁺ ) and at least one hydroxide ion (OH ⁻ ). The hydroxide of the tetravalent metal element may include anions other than hydroxide ions (for example, nitrate ion NO ₃ ^- and sulfate ion SO ₄ ^2- ). For example, the hydroxide of a tetravalent metal element may also include an anion (for example, nitrate ion NO ₃ ^- and sulfate ion SO ₄ ^2- ) bonded to the tetravalent metal element.

Compared with abrasive particles containing silicon dioxide, cerium oxide, etc., abrasive particles containing hydroxides of tetravalent metal elements are more reactive with insulating materials (such as silicon oxide), and can be used at higher grinding speeds for insulating materials. Grind. As the abrasive grains containing a hydroxide of a tetravalent metal element, particles containing a hydroxide of a tetravalent metal element, composite particles with particles containing a cerium oxide, and a hydroxide containing a tetravalent metal element can also be used. Composite particles with silicon dioxide.

From the viewpoint of further improving the polishing rate of the insulating material, the hydroxide of the metal element (such as a tetravalent metal element) is preferably selected from the group consisting of a hydroxide of a rare earth element and a hydroxide of zirconium. At least one of these is more preferably a hydroxide containing a rare earth element. Examples of the quaternary rare earth elements that can be obtained include lanthanide series such as cerium, samarium, and ytterbium. Among them, lanthanide series is preferred, and cerium is more preferred from the viewpoint that the polishing rate of the insulating material is more excellent. A hydroxide of a rare earth element and a hydroxide of zirconium may be used in combination, or two or more kinds of the hydroxide of a rare earth element may be selected and used.

When the content of the hydroxide of a metal element (such as a tetravalent metal element) in the abrasive grains exceeds 0% by mass and is 50% by mass or less, the total abrasive grains (all the abrasive grains contained in the polishing liquid) are taken as In general, the content of the hydroxide of a metal element (such as a tetravalent metal element) is preferably in the following range. From the viewpoint of further improving the polishing rate of the insulating material, the lower limit of the content of the hydroxide of the metal element is preferably 5 mass% or more, more preferably 6 mass% or more, still more preferably 7 mass% or more, and particularly preferably 8 mass% or more, and more preferably 9 mass% or more. The upper limit of the content of the hydroxide of the metal element is preferably 50% by mass or less, more preferably 40% by mass or less, from the viewpoint that it is easy to prepare a polishing liquid and the polishing characteristics (grinding speed of the insulating material, etc.) are more excellent. It is preferably 30% by mass or less, particularly preferably 20% by mass or less, very preferably 15% by mass or less, and very preferably 10% by mass or less. From this viewpoint, the content of the hydroxide of the metal element is more preferably 5 to 50% by mass.

When the content of the hydroxide of a metal element (such as a tetravalent metal element) in the abrasive grains exceeds 50% by mass, the metal element (quaternary substance) is based on the entire abrasive grains (all abrasive grains contained in the polishing liquid). The content of hydroxides such as valence metal elements is preferably in the following range. From the viewpoint of further improving the polishing rate of the insulating material, the lower limit of the content of the hydroxide of the metal element is preferably more than 50% by mass, more preferably 70% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more, very preferably 98% by mass or more, and very preferably 99% by mass or more. Regarding the abrasive grains, it is preferable that the abrasive grains substantially contain a hydroxide (substantially a metal element (such as a tetravalent metal element)) of hydroxide (essentially) from the viewpoint that it is easy to prepare a polishing liquid and the polishing characteristics (such as the polishing rate of the insulating material) are more excellent. 100% by mass of the upper abrasive grains are hydroxides of metal elements (such as tetravalent metal elements).

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

It is preferable that the average particle diameter of the abrasive grains in the slurry of the polishing liquid or the polishing liquid set mentioned later is the following range. From the viewpoint of further improving the polishing rate of the insulating material, the lower limit of the average particle diameter of the abrasive particles is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, and particularly preferably 25 nm or more. From the viewpoint of the dispersibility of the abrasive particles and further suppressing damage to the surface to be polished, the upper limit of the average particle diameter of the abrasive particles is preferably 1000 nm or less, more preferably 800 nm or less, and even more preferably 700 nm or less. Particularly preferred is below 600 nm, very preferred below 500 nm, and very preferred below 400 nm. From this viewpoint, the average particle diameter of the abrasive particles is more preferably from 10 nm to 1000 nm.

When the abrasive grain contains a hydroxide of a metal element (such as a tetravalent metal element), the upper limit of the average grain size of the abrasive grains is from the viewpoint of the dispersibility of the abrasive grains and further suppressing damage to the surface to be polished. It is preferably 200 nm or less, more preferably 100 nm or less, still more preferably 50 nm or less, and particularly preferably 30 nm or less.

In the case where the abrasive grain contains an oxide of a metal element, from the viewpoint of further improving the polishing rate of the insulating material, the lower limit of the average particle diameter of the abrasive grain is preferably 50 nm or more, more preferably 100 nm or more, and further preferably Above 200 nm, particularly preferably above 300 nm, and extremely preferably above 330 nm.

The "average particle diameter" of the abrasive particles means the average secondary particle diameter of the abrasive particles. The average particle size of the abrasive particles can be, for example, a light diffraction scattering particle size distribution meter (for example, manufactured by Beckman Coulter Co., Ltd., trade name: N5, or manufactured by Microtrac-bel). Trade name: Microtrac MT3300EXII) The slurry in the polishing liquid or a polishing liquid set described later is measured.

By using a water-soluble compound containing a trivalent rare-earth element, the polishing rate of the insulating material can be increased regardless of whether the boundary potential (surface potential) of the abrasive particles in the polishing liquid is positive or negative. The boundary potential of the abrasive particles in the polishing liquid may be positive or negative. From the viewpoint of excellent dispersibility of the abrasive particles, the lower limit of the absolute value of the boundary potential of the abrasive particles in the polishing liquid is preferably 10 mV or more, more preferably 20 mV or more, and further preferably 25 mV or more. 30 mV or more, 40 mV or more, 50 mV or more. The upper limit of the absolute value of the boundary potential of the abrasive grain is not particularly limited, and may be, for example, 200 mV or less. From this viewpoint, the absolute value of the boundary potential of the abrasive particles is more preferably 10 mV to 200 mV.

The boundary potential of the abrasive particles means the surface potential of the dispersed abrasive particles. For example, a dynamic light scattering-type boundary potential measurement device (for example, manufactured by Beckman Coulter Co., Ltd.) can be used for the boundary potential of the abrasive particles in the slurry of the polishing solution or a slurry set of a polishing solution described later. Trade name: Delsa Nano (C). The boundary potential of the abrasive particles can be adjusted using additives. For example, abrasive grains having a negative boundary potential can be obtained by bringing a water-soluble polymer (such as polyacrylic acid) into contact with abrasive grains containing cerium dioxide.

In the case where the abrasive particles contain a hydroxide of a tetravalent metal element, by adjusting the content of the hydroxide of the tetravalent metal element, the chemical interaction between the abrasive particles and the surface to be polished can be increased, thereby further improving the polishing speed of the insulating material. . In this case, based on the total mass of the polishing liquid, the lower limit of the content of the hydroxide of the tetravalent metal element is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.03% by mass or more. Especially preferred is 0.05 mass% or more. From the viewpoint that it is easy to avoid the agglomeration of the abrasive particles, the chemical interaction between the abrasive particles and the surface to be polished is improved, and the characteristics of the abrasive particles can be effectively utilized, based on the total mass of the polishing liquid, the hydrogen of the tetravalent metal element The upper limit of the content of the oxide is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, particularly preferably 2% by mass or less, extremely preferably 1% by mass or less, and very preferably 0.5%. Mass% or less, more preferably 0.3 mass% or less, and even more preferably 0.1 mass% or less. From this viewpoint, the content of the hydroxide of the tetravalent metal element is more preferably 0.005% to 5% by mass based on the total mass of the polishing liquid.

From the viewpoint of further improving the polishing rate of the insulating material, based on the total mass of the polishing liquid, the lower limit of the content of the abrasive grains exceeds 0% by mass, preferably 0.01% by mass or more, and more preferably 0.03% by mass or more. It is preferably at least 0.05% by mass. From the viewpoint of improving the storage stability of the polishing liquid, based on the total mass of the polishing liquid, the upper limit of the content of the abrasive particles is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 6% by mass. the following. From this viewpoint, the content of the abrasive particles is more preferably 0.01% by mass to 10% by mass based on the total mass of the polishing liquid.

In addition, it is preferable from the viewpoint of further reducing the cost and polishing damage by further reducing the content of the abrasive particles. From this viewpoint, the upper limit of the content of the abrasive particles is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, particularly preferably 2% by mass or less, and extremely preferably less than 2% by mass. %, Very preferably 1.5 mass% or less, more preferably 1 mass% or less, even more preferably 0.7 mass% or less, and particularly preferably 0.5 mass% or less. From the viewpoint, based on the total mass of the polishing liquid, the content of the abrasive particles is more preferably more than 0% by mass and 4% by mass, and still more preferably more than 0% by mass and 1.5% by mass or less.

[Absorbance] The abrasive grains are preferably hydroxides containing a tetravalent metal element, and satisfy at least one of the following conditions (a) and (b). The "aqueous dispersion" in which the content of the abrasive grains is adjusted to a predetermined amount means a liquid containing a predetermined amount of abrasive grains and water. (A) Abrasive particles provide an absorbance of 1.00 or more for light having a wavelength of 400 nm in an aqueous dispersion in which the content of the abrasive particles is adjusted to 1.0% by mass. (B) Abrasive particles provide an absorbance of 1.000 or more for light having a wavelength of 290 nm in an aqueous dispersion whose content of the abrasive particles is adjusted to 0.0065% by mass.

Regarding the condition (a), the polishing particles can be further improved by providing polishing particles having an absorbance of 1.00 or more for light having a wavelength of 400 nm by using the aqueous dispersion liquid in which the content of the polishing particles is adjusted to 1.0% by mass. speed. The reason is not necessarily clear, but the present inventors considered it as follows. That is, it is considered that particles containing M (OH) _a X _b (wherein, a + b × c = 4) are formed as part of the abrasive particles based on the production conditions of the hydroxide of the tetravalent metal element (in addition, such particles) also "include hydroxides of tetravalent metal elements abrasive grains"), the M (OH) _a X _b comprises a tetravalent metal (M ^4+), 1 one to three hydroxide ion (OH ^- ) And one to three anions (X ^c- ). It is thought that in M (OH) _a X _b , the electron-withdrawing anion (X ^c- ) acts to increase the reactivity of hydroxide ions. As the amount of M (OH) _a X _b increases, the polishing rate increases. improve. In addition, since particles containing M (OH) _a X _b absorb light at a wavelength of 400 nm, it is considered that the amount of M (OH) _a X _b is increased to increase the absorbance for light with a wavelength of 400 nm, and polishing is accompanied by this. Speed up.

It is considered that the abrasive grains containing a hydroxide of a tetravalent metal element include 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 grains containing the hydroxide of the tetravalent metal element containing M (OH) _a X _b can be confirmed by the following method: After the abrasive grains are sufficiently washed with pure water, the whole is analyzed by a Fourier transform infrared spectrophotometer. The reflection measurement method (Fourier transform Infrared Spectrometer Attenuated Total Reflection method, FT-IR ATR method) detected a peak corresponding to an anion (X ^c- ). The existence of anions (X ^c- ) can also be confirmed by X-ray Photoelectron Spectroscopy (XPS method).

Here, it was confirmed that the absorption peak at a wavelength of 400 nm of M (OH) _a X _b (for example, M (OH) ₃ X) was much smaller than the absorption peak at a wavelength of 290 nm described later. In view of this, the present inventors studied the absorbance by using an aqueous dispersion having a relatively large abrasive content and an abrasive content of 1.0% by mass, which is easy to detect a large absorbance. As a result, it was found in the aqueous dispersion that the When the light having a wavelength of 400 nm is an abrasive particle having an absorbance of 1.00 or more, the effect of improving the polishing rate is excellent.

From the viewpoint that it is easy to polish the insulating material at a more excellent polishing rate, the lower limit of the absorbance for light having a wavelength of 400 nm is preferably 1.50 or more, more preferably 1.55 or more, and even more preferably 1.60 or more.

Regarding the condition (b), the polishing particles can be further improved by providing polishing particles having an absorbance of 1.000 or more for light having a wavelength of 290 nm by using in an aqueous dispersion having an abrasive particle content of 0.0065% by mass. speed. The reason is not necessarily clear, but the present inventors considered it as follows. That is, particles containing M (OH) _a X _b (for example, M (OH) ₃ X) generated according to manufacturing conditions of a hydroxide of a tetravalent metal element and the like have an absorption peak around a wavelength of 290 nm in calculation. includes, for example _{^{Ce 4+ (OH -) 3 NO}} 3 - particles having an absorption peak at a wavelength 290 nm. Therefore, it is considered that the increase in the amount of M (OH) _a X _b increases the absorbance with respect to light having a wavelength of 290 nm, and the polishing rate is increased accordingly.

Here, the absorbance for light near a wavelength of 290 nm tends to be detected more as it exceeds the measurement limit. In view of this, the present inventors studied the absorbance by using an aqueous dispersion having a relatively small content of abrasive particles and easily detecting a small absorbance with an abrasive particle content of 0.0065% by mass. As a result, it was found in the aqueous dispersion that the In the case of abrasive particles having an absorbance of 1.000 or more for light having a wavelength of 290 nm, the effect of improving the polishing rate is excellent.

From the viewpoint of polishing the insulating material at a more excellent polishing rate, the lower limit of the absorbance for light having a wavelength of 290 nm is more preferably 1.050 or more, further preferably 1.100 or more, particularly good 1.130 or more, and extremely good 1.150 or more. . The upper limit of the absorbance of light having a wavelength of 290 nm is not particularly limited, but is preferably 10.00 or less, for example.

In the case where an abrasive particle having an absorbance of 1.00 or more for light having a wavelength of 400 nm is provided in an aqueous dispersion whose content of the abrasive particles is adjusted to 0.0065% by mass, and an absorbance of 1.000 or more for light having a wavelength of 290 nm is provided In this way, the insulating material can be polished at a more excellent polishing speed.

In addition, a hydroxide of a tetravalent metal element (for example, M (OH) _a X _b ) tends not to absorb light having a wavelength of 450 nm or more (particularly, a wavelength of 450 to 600 nm). Therefore, it is preferable that the content of the abrasive particles is adjusted to 0.0065% by mass (65%) from the viewpoint of suppressing the adverse effect on the polishing by the inclusion of impurities and polishing the insulating material at a more excellent polishing rate. ppm) in water dispersion, it provides an absorbance of 0.010 or less for light with a wavelength of 450 nm to 600 nm. That is, it is preferable that the absorbance of all the light in the range of wavelengths of 450 nm to 600 nm in the water dispersion liquid in which the content of the abrasive particles is adjusted to 0.0065% by mass does not exceed 0.010. The upper limit of the absorbance for light having a wavelength of 450 nm to 600 nm is more preferably less than 0.010. The lower limit of the absorbance for light having a wavelength of 450 nm to 600 nm is preferably 0.

The absorbance of the aqueous dispersion can be measured using, for example, a spectrophotometer (device name: U3310) manufactured by Hitachi, Ltd. Specifically, for example, an aqueous dispersion liquid in which the content of the abrasive particles is adjusted to 1.0% by mass or 0.0065% by mass is prepared as a measurement sample. About 4 mL of this measurement sample was placed in a 1 cm square tank, and the tank was set in the device. Next, the absorbance was measured in a wavelength range of 200 nm to 600 nm, and the absorbance was determined based on the obtained chart.

[Light transmittance] The polishing liquid of this embodiment is preferably transparent to visible light (transparent or nearly transparent under visual observation). Specifically, it is preferable that the polishing particles contained in the polishing liquid of this embodiment are 50% / 50% of light for a light having a wavelength of 500 nm in an aqueous dispersion whose content of the polishing particles is adjusted to 1.0% by mass. Transmittance above cm. This makes it possible to further suppress the decrease in the polishing rate due to the addition of the additive, and therefore it is easy to maintain the polishing rate and obtain other characteristics. From this viewpoint, the lower limit of the light transmittance is more preferably 60% / cm or more, more preferably 70% / cm or more, particularly preferably 80% / cm or more, and extremely preferably 90% / cm or more. It is preferably 92% / cm or more. The upper limit of the light transmittance is 100% / cm.

The reason why the reduction in the polishing rate can be suppressed by adjusting the light transmittance of the polishing particles as described above is not known in detail, but the present inventors considered as follows. It is considered that chemical action is dominant in abrasive grains containing a hydroxide of a tetravalent metal element (cerium or the like) compared to mechanical action. Therefore, it is considered that the number of abrasive particles is more helpful to the polishing speed than the size of the abrasive particles.

When the light transmittance in the aqueous dispersion having a content of abrasive particles of 1.0% by mass is low, it is considered that among the abrasive particles present in the aqueous dispersion, relatively large particles (hereinafter referred to as "coarse" particle"). When an additive (such as polyvinyl alcohol (Poly Vinyl Alcohol, PVA)) is added to a polishing liquid containing such abrasive particles, coarse particles are used as cores to aggregate other particles as shown in FIG. 1. As a result, it is considered that the number of abrasive grains (the number of effective abrasive grains) acting on the surface to be polished per unit area is reduced, and the specific surface area of the abrasive grains in contact with the surface to be polished is reduced, thereby causing a reduction in the polishing speed.

On the other hand, when the light transmittance is high in an aqueous dispersion having a content of abrasive particles of 1.0% by mass, it is considered that the abrasive particles present in the aqueous dispersion are in a state where there are "coarse particles". In the case where the amount of coarse particles is small as described above, even if an additive (for example, polyvinyl alcohol) is added to the polishing liquid as shown in FIG. 2, the number of coarse particles that become cohesive nuclei is small, so that the abrasive particles can be prevented from agglomerating with each other. Or the size of the agglomerated particles is smaller than that of the agglomerated particles shown in FIG. 1. As a result, it is considered that it is difficult to reduce the polishing rate by maintaining the number of abrasive grains (the number of effective abrasive grains) that act on the surface to be polished per unit area and the specific surface area of the abrasive grains in contact with the surface to be polished.

In the study of the present inventors, it was found that even if the polishing liquid having the same particle diameter as measured by a general particle diameter measuring device can exist in the polishing liquid that is transparent (high light transmittance) under visual observation, and Visually it is a turbid (low light transmittance) polishing liquid. In this case, it is considered that the coarse particles that can perform the above-mentioned functions contribute to the reduction in the polishing rate even in a very small amount that cannot be detected by a general particle size measuring device.

In addition, it has been found that even if repeated filtration is performed repeatedly to reduce coarse particles, the phenomenon that the polishing rate is reduced due to additives has not been improved, and the above-mentioned effect of improving the polishing rate by absorbance cannot be fully exhibited. Therefore, the present inventors have studied the manufacturing method of the abrasive grains, etc., and found that the problem can be solved by using abrasive grains having a high light transmittance in the aqueous dispersion.

The transmittance is a transmittance for light having a wavelength of 500 nm. The light transmittance can be measured with a spectrophotometer. Specifically, the measurement can be performed using, for example, a spectrophotometer U3310 (device name) manufactured by Hitachi, Ltd.

As a more specific measurement method, an aqueous dispersion liquid in which the content of the abrasive grains was adjusted to 1.0% by mass was prepared as a measurement sample. Approximately 4 mL of the measurement sample was placed in a 1 cm square tank, and the tank was set in the device for measurement.

The absorbance and light transmittance of the abrasive particles contained in the polishing liquid in the aqueous dispersion can be obtained by removing solid components other than the abrasive particles and liquid components other than water, and then preparing an aqueous dispersion with a predetermined content of abrasive particles. This aqueous dispersion was measured. Although it varies depending on the components contained in the polishing liquid, solid or liquid components can be removed by, for example, centrifugation using a centrifuge that applies a gravitational acceleration of several thousand G or less, Centrifugation methods such as ultracentrifugation in ultracentrifuges; chromatography methods such as distribution chromatography, adsorption chromatography, gel permeation chromatography, ion exchange chromatography; natural filtration, vacuum filtration, pressure filtration, Filtration methods such as ultrafiltration; distillation methods such as reduced pressure distillation and atmospheric pressure distillation, etc., may also be suitably combined.

For example, when a compound having a weight-average molecular weight of tens of thousands (for example, 50,000 or more) is included, as a method for separating the abrasive particles, a chromatography method, a filtration method, or the like can be cited. Among them, a gel permeation layer is preferred At least one of a group consisting of analysis and ultrafiltration. When the filtration method is used, the abrasive particles contained in the polishing liquid can be passed through the filter by setting appropriate conditions. When a compound having a weight-average molecular weight of tens of thousands or less (for example, less than 50,000) is included, a method for separating the abrasive particles includes a chromatography method, a filtration method, a distillation method, and the like, and is preferably selected from a gel-permeable layer At least one of the group consisting of analysis, ultrafiltration and vacuum distillation. When a plurality of types of abrasive particles are contained, as a method of separating the abrasive particles, a filtration method, a centrifugal separation method, and the like can be mentioned. In the case of filtration, the filtrate contains more grinding of a hydroxide containing a tetravalent metal element. In the case of centrifugation, the particles more contain abrasive particles containing a hydroxide of a tetravalent metal element in the liquid phase.

As a method for separating the abrasive grains by chromatography, for example, the abrasive grain components can be fractionated and / or other components can be fractionated under the following conditions. Sample solution: 100 μL of polishing liquid Detector: manufactured by Hitachi, Ltd., UV-VIS detector, trade name "L-4200" Wavelength: 400 nm Integrator: manufactured by Hitachi, Ltd., GPC integrator, product Name "D-2500" Pump: manufactured by Hitachi, Ltd., trade name "L-7100" Column: manufactured by Hitachi Chemical Co., Ltd., packed column for high-performance liquid chromatography (HPLC) Product name "GL-W550S" Eluent: Deionized water Measurement temperature: 23 ° C Flow rate: 1 mL / min (pressure is about 40 kg / cm ² to 50 kg / cm ² ) Measurement time: 60 minutes

Due to the components contained in the polishing liquid, there is a possibility that the components of the polishing particles cannot be separated even under the above-mentioned conditions. In this case, the amount of the sample solution, the type of the column, the type of the eluent, and the measurement temperature can be determined. , Flow rate, etc. are optimized for separation. In addition, by adjusting the pH value of the polishing liquid, there is a possibility that the components contained in the polishing liquid can be separated from the polishing particles by adjusting the distillation removal time of the components. When an insoluble component is present in the polishing liquid, it is preferable to remove the insoluble component by filtration, centrifugation, or the like, as necessary.

[Production Method of Tetravalent Metal Element Hydroxide] The tetravalent metal element hydroxide can be produced by reacting a salt (metal salt) of a tetravalent metal element with an alkali source (alkali). The tetravalent metal element hydroxide is preferably produced by mixing a salt of the tetravalent metal element with an alkaline solution (for example, an alkaline aqueous solution). Thereby, particles with extremely fine particle diameters can be obtained, and a polishing liquid having a more excellent effect of reducing polishing damage can be obtained. Such a technique is disclosed in, for example, Patent Literature 7 and Patent Literature 8. The hydroxide of a tetravalent metal element can be obtained by mixing a metal salt solution (for example, an aqueous metal salt solution) of a salt of a tetravalent metal element with an alkaline solution. As the salt of a tetravalent metal element, a conventionally known one can be used without particular limitation, and examples thereof include: M (NO ₃ ) ₄ , M (SO ₄ ) ₂ , M (NH ₄ ) ₂ (NO ₃ ) ₆ , M ( NH ₄ ) ₄ (SO ₄ ) ₄ (M represents a rare earth element), Zr (SO ₄ ) ₂ · 4H ₂ O, and the like. M is preferably chemically active cerium (Ce).

(Additive) The polishing liquid of this embodiment contains an additive. Here, the "additives" refer to polishing liquids other than the polishing particles and liquid media for adjusting polishing characteristics such as polishing speed and polishing selectivity, polishing particle dispersion, storage stability, and the like. substance.

[Water-soluble compound containing trivalent rare-earth element] The polishing liquid of the present embodiment contains a polishing solution containing more than 0% by mass to less than 0.05% by mass (based on the total mass of the polishing liquid) of a water-soluble compound containing a trivalent rare earth element. The reason why the polishing rate is increased by using this water-soluble compound is not necessarily clear, but the inventors speculated as follows. That is, it is estimated that the predetermined amount of the water-soluble compound containing a trivalent rare-earth element changes the valence of the surface of the abrasive grains and easily forms a bond between the surface of the abrasive grains and the surface of the insulating material (for example, it is easy to form The reaction layer is removed by grinding), thereby promoting the grinding of the insulating material. For example, when polishing a silicon oxide film with abrasive grains containing a cerium compound, it is estimated that the predetermined amount of the water-soluble compound containing a trivalent rare-earth element changes the valence of cerium on the surface of the abrasive grains and makes it easier for the abrasive grains. Since a bond is formed between the surface and silicon (Si) on the surface of the silicon oxide film (for example, a reaction layer that is easily removed by polishing), the polishing of the silicon oxide film is promoted.

The "water-soluble" in the water-soluble compound refers to a compound that dissolves 0.1 g or more with respect to 100 g of water.

Examples of the trivalent rare earth element in the water-soluble compound include lanthanoids, yttrium, and the like. Examples of the lanthanide of the trivalent rare earth element include cerium and lanthanum. From the viewpoint of further increasing the polishing rate of the insulating material, the trivalent rare earth element preferably contains cerium.

Examples of the water-soluble compound include nitrates, ammonium salts, chlorides, phosphates, sulfates, and acetates. From the viewpoint of further improving the polishing rate of the insulating material, acetates are preferred.

From the viewpoint of further improving the polishing rate of the insulating material, the water-soluble compound containing a trivalent rare earth element is preferably selected from the group consisting of cerium nitrate, cerium ammonium nitrate, cerium chloride, cerium phosphate, cerium sulfate, and cerium acetate. At least one of the group.

Based on the total mass of the polishing liquid, the content of the water-soluble compound containing a trivalent rare earth element exceeds 0% by mass and less than 0.05% by mass. From the viewpoint of efficiently utilizing the interaction between a water-soluble compound containing a trivalent rare earth element and abrasive grains (for example, abrasive grains containing tetravalent cerium) to further improve the polishing rate of an insulating material, Based on the total mass, the lower limit of the content of the water-soluble compound containing a trivalent rare earth element is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, still more preferably 0.003% by mass or more, and particularly preferably 0.004% by mass or more , Excellent is 0.005 mass% or more. From the viewpoint of reducing the cost of the polishing solution and preventing the excessive grinding of the recessed portion during polishing of the patterned wafer having the unevenness, based on the total mass of the polishing solution, a water-soluble compound containing a trivalent rare earth element is included. The upper limit of the content is preferably 0.04% by mass or less, more preferably 0.03% by mass or less, still more preferably 0.02% by mass or less, and particularly preferably 0.01% by mass or less.

[Optional Additives] The polishing liquid of the present embodiment may further contain any additives other than water-soluble compounds containing trivalent rare-earth elements (equivalent to water-soluble compounds containing trivalent rare-earth elements) for the purpose of adjusting polishing characteristics and the like. Except for compounds). Examples of the optional additives include polyoxyalkylene compounds, water-soluble polymers, acid components (such as acetic acid), oxidants (such as hydrogen peroxide), insoluble compounds containing trivalent rare earth elements (such as cerium carbonate), and Valence rare earth compounds (except for components contained in abrasive grains), etc. Each of these additives may be used alone or in combination of two or more.

Additives such as a polyoxyalkylene compound, a water-soluble polymer, and an acid component have the effects of improving the dispersion stability of the polishing liquid, and capable of polishing the insulating material (for example, silicon oxide) at a higher speed. In addition, the insulating material (for example, silicon oxide) can be polished at a higher speed, thereby improving the step-elimination property and achieving higher flatness. The reason for this is presumably that the polishing rate of the convex portion is significantly increased compared to the polishing rate of the concave portion.

Water-soluble polymers have the ability to adjust the dispersion stability, flatness, and in-plane uniformity of abrasive particles, the selectivity of silicon oxide to silicon nitride (the polishing speed of silicon oxide / the polishing speed of silicon nitride), and the relative Effects on polishing characteristics such as polishing selectivity of polycrystalline silicon (polishing speed of silicon oxide / polishing speed of polycrystalline silicon) and the like. Here, the "water-soluble polymer" is defined as a polymer that dissolves 0.1 g or more with respect to 100 g of water. The polymer corresponding to the polyoxyalkylene compound is not included in the "water-soluble polymer".

The water-soluble polymer is not particularly limited, and examples thereof include polyacrylic polymers such as polyacrylic acid, polyacrylic acid copolymers, polyacrylates, and polyacrylic acid copolymer salts; polymethacrylic acid and polymethacrylic acid salts Polyacrylamide; Polyacrylamide; Polydimethylacrylamide; Polysaccharides such as carboxymethyl cellulose, agar, curdlan, dextrin, cyclodextrin, polytriglucose, etc .; polyethylene Ethylene polymers such as alcohol, polyvinylpyrrolidone, polyacrolein; glycerol polymers such as polyglycerin and polyglycerin derivatives; polyethylene glycol and the like. The water-soluble polymer may be used singly or in combination of two or more kinds.

In the case of using a water-soluble polymer, from the viewpoint of suppressing the sedimentation of the abrasive particles and obtaining the effect of adding the water-soluble polymer, the lower limit of the content of the water-soluble polymer is preferably based on the total mass of the polishing liquid. 0.0001% by mass or more, more preferably 0.001% by mass or more, still more preferably 0.01% by mass or more, and particularly preferably 0.1% by mass or more. From the viewpoint of suppressing the sedimentation of the abrasive particles and obtaining the effect of adding water-soluble polymers, the upper limit of the content of the water-soluble polymers is preferably 10% by mass or less, more preferably 8% by mass based on the total mass of the polishing liquid % Or less, more preferably 6 mass% or less, and particularly preferably 5 mass% or less. When a plurality of compounds are used as the water-soluble polymer, it is preferable that the total content of each compound satisfies the above range.

From the viewpoint of further improving the polishing rate of the insulating material, based on the total mass of the polishing liquid, the upper limit of the content of the oxidant is preferably less than 0.05% by mass, more preferably 0.04% by mass or less, and still more preferably 0.01% by mass or less. Particularly preferred is 0.005 mass% or less, and extremely preferred is 0.001 mass% or less. The polishing liquid of the present embodiment may be in a state that does not substantially contain an oxidant (the content of the oxidant is substantially 0% by mass based on the total mass of the polishing liquid).

It is preferable that the polishing liquid of this embodiment does not contain a tetravalent rare-earth element (except the component contained in a polishing particle) as an active ingredient. For example, the polishing liquid of the present embodiment may be in a state that does not substantially contain a tetravalent rare earth element (except for components contained in the abrasive grains) as an effective component (a tetravalent rare earth element (containing in the abrasive grains) (Except for components), the content is substantially 0% by mass based on the total mass of the polishing liquid).

(Liquid medium) The liquid medium in the polishing liquid of this embodiment is not particularly limited, and water such as deionized water and ultrapure water is preferred. The content of the liquid medium may be the remainder of the polishing liquid excluding the content of other constituent components, and is not particularly limited.

(Characteristics of Polishing Liquid) The pH of the polishing liquid of this embodiment mainly affects the polishing rate. From the viewpoint of further improving the polishing rate of the insulating material, the lower limit of the pH value is preferably 2.0 or more, more preferably 2.5 or more, still more preferably 2.8 or more, particularly preferably 3.0 or more, and very preferably 3.2 or more. From the viewpoint that the polishing rate of the insulating material (for example, silicon oxide) is more excellent, the upper limit of the pH value is preferably 10.0 or less, more preferably 8.0 or less, further preferably 7.5 or less, particularly preferably 7.0 or less, and extremely good 6.5. Hereinafter, it is very preferably 6.0 or less, and even more preferably 5.0 or less. From the viewpoint of excellent storage stability of the polishing liquid, the pH of the polishing liquid is more preferably 2.0 to 10.0, and further preferably 2.0 to 7.0. The pH value of the polishing liquid was defined as the pH value at a liquid temperature of 25 ° C.

The pH value of the polishing liquid can be adjusted by acid components such as inorganic acids and organic acids; alkali components such as ammonia, sodium hydroxide, tetramethylammonium hydroxide (TMAH), imidazole, and alkanolamine. To stabilize the pH, a buffering agent may be added. It is also possible to prepare a buffer solution (a liquid containing a buffering agent) and add a buffering agent. Examples of such a buffer include acetate buffer and phthalate buffer.

The pH value of the polishing liquid according to this embodiment can be measured using a pH meter (for example, model PHL-40 manufactured by Denki Kogyo Co., Ltd.). Specifically, for example, a phthalate pH buffer solution (pH: 4.01) and a neutral phosphate pH buffer solution (pH: 6.86) can be used as standard buffers to perform two pH meter measurements. After the calibration, the electrode of the pH meter was put into the polishing solution, and the value after the stabilization for more than 2 minutes was measured. The liquid temperature of the standard buffer solution and the polishing solution was set to 25 ° C.

<Polishing liquid set and additive liquid> The polishing liquid of this embodiment can be stored as a one-liquid polishing liquid containing at least polishing particles, a water-soluble compound containing a trivalent rare earth element, and a liquid medium, and it can also be stored, or it can be stored. A multi-liquid type (for example, a multi-liquid type in which the constituent components of the polishing liquid are divided into a slurry and an additive liquid, such that the slurry (first liquid) and the additive liquid (second liquid) are mixed to form the polishing liquid) A two-liquid type) polishing solution is stored in sets. The slurry contains, for example, at least abrasive particles and a liquid medium. The additive liquid contains, for example, a water-soluble compound containing at least a trivalent rare earth element, and a liquid medium. It is preferable that the water-soluble compound containing a trivalent rare-earth element, an arbitrary additive, and a buffering agent are contained in an additive solution in a slurry and an additive solution. Furthermore, the constituents of the polishing liquid may be stored in a polishing liquid set divided into three or more liquids.

In the polishing liquid set, a slurry and an additive liquid are mixed immediately before or during polishing to prepare a polishing liquid. In addition, the one-liquid polishing liquid can be stored as a storage liquid for a polishing liquid in which the content of the liquid medium is reduced, and can be used by diluting with a liquid medium during polishing. The multi-liquid polishing liquid set can be stored as a slurry storage liquid and an additive liquid storage liquid with a reduced content of the liquid medium, and can be diluted with the liquid medium for use during polishing.

In the case of a one-liquid polishing liquid, as a method of supplying the polishing liquid to the polishing platen, a method of directly feeding the liquid and supplying the polishing liquid can be used; and the storage liquid for the polishing liquid and the liquid medium using different pipes A method of supplying a liquid, mixing and mixing these components and supplying the same; a method of mixing and supplying a polishing liquid storage liquid and a liquid medium in advance, and the like.

When a multi-liquid polishing solution set is divided into a slurry and an additive liquid and stored, the polishing rate can be adjusted by arbitrarily changing the mixing of these liquids. When polishing is performed using a polishing liquid set, there are methods described below as methods for supplying a polishing liquid to a polishing platen. For example, it is possible to use a method of feeding the slurry and the additive liquid using different pipes, and combining and supplying the pipes, and supplying the slurry; using different pipes to store the slurry storage liquid, the additive storage liquid, and the liquid. A method for feeding liquids from a medium and mixing and mixing the materials and supplying them; a method for mixing and supplying a slurry and an additive liquid in advance; and mixing and supplying a slurry storage liquid, an additive liquid storage liquid, and a liquid medium in advance Methods etc. Alternatively, a method of separately supplying the slurry and the additive liquid in the polishing liquid set to the polishing platen may be used. In this case, the surface to be polished is polished using a polishing liquid obtained by mixing a slurry and an additive liquid on a polishing platen.

In addition, the polishing liquid set of this embodiment may be divided into a polishing liquid containing at least the essential components and an additive liquid containing at least an optional component such as an oxidizing agent (for example, hydrogen peroxide). In this case, polishing is performed using a mixed liquid obtained by mixing a polishing liquid and an additive liquid (this mixed liquid also corresponds to a "polishing liquid"). In addition, as for the polishing liquid set of the present embodiment, as a polishing liquid set divided into three or more liquids, the polishing liquid set may be divided into a liquid containing at least a part of the essential components and a liquid containing at least the remaining part of the essential components. A state of a liquid and an additive liquid containing at least an arbitrary component. Each of the liquids constituting the polishing liquid set may be stored as a storage liquid having a reduced content of the liquid medium.

<Polishing method> The polishing method (polishing method of the substrate, etc.) of this embodiment may include a polishing step of polishing the surface to be polished (such as the surface to be polished of the substrate) using the one-liquid polishing liquid, or may include using A polishing step of polishing a surface to be polished (such as a surface to be polished of a substrate) by a polishing liquid obtained by mixing the slurry in the polishing liquid set with an additive liquid.

In the polishing step, the polishing solution is supplied between the material to be polished and the polishing pad, for example, in a state where the material to be polished having a substrate of the material to be polished is pressed against a polishing pad (abrasive cloth) of a polishing platen. , The substrate and the polishing platen are relatively moved to polish the surface to be polished of the material to be polished. In the grinding step, for example, at least a part of the material to be ground is removed by grinding.

Examples of the substrate to be polished include a substrate to be polished. Examples of the substrate to be polished include a substrate on which a material to be polished is formed on a substrate related to semiconductor device manufacturing (for example, a semiconductor substrate on which an STI pattern, a gate pattern, and a wiring pattern is formed). Examples of the material to be polished include insulating materials such as silicon oxide. The material to be ground may be a single material or multiple materials. When a plurality of materials are exposed on the surface to be polished, these materials can be regarded as the material to be polished. The material to be polished may be a film (a film to be polished), or an insulating film such as a silicon oxide film.

The polishing liquid (such as an insulating material such as silicon oxide) formed on such a substrate is polished with the polishing liquid to remove excess portions, thereby eliminating unevenness on the surface of the polishing material and obtaining a polished surface. The surface of the material is an overall smooth surface. The polishing liquid of this embodiment is preferably used for polishing a surface to be polished containing silicon oxide.

Examples of a method for manufacturing a material to be polished using the polishing liquid of this embodiment include: a CVD method such as a low pressure chemical vapor deposition (CVD) method, a quasi-normal pressure CVD method, and a plasma CVD method; A spin coating method or the like in which a liquid raw material is coated on a substrate.

Hereinafter, a polishing method of a substrate (for example, a substrate having an insulating material formed on a semiconductor substrate) will be described as an example, and the polishing method of this embodiment will be described. In the polishing method of this embodiment, as the polishing device, a general polishing device including a holder capable of holding a substrate having a surface to be polished and a polishing platen to which a polishing pad can be attached can be used. A motor or the like that has a variable number of revolutions is attached to each of the holder and the polishing platen. The polishing device may be, for example, a polishing device manufactured by Ebara Manufacturing Co., Ltd .: F-REX300, or a polishing device manufactured by Applied Materials: Reflexion.

As the polishing pad, a general non-woven fabric, foam, non-foam, or the like can be used. The polishing pad can be made of polyurethane, acrylic resin, polyester, acrylic-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly-4-methylpentene, cellulose, cellulose Esters, polyamines (for example, nylon (brand name) and polyaramide), polyimide, polyimide amines, polysiloxane copolymers, oxetane compounds, phenol resins, polybenzenes Resins such as ethylene, polycarbonate, epoxy resin. As the material of the polishing pad, particularly from the viewpoint of more excellent polishing speed and flatness, it is preferably selected from the group consisting of foamed polyurethane and non-foamed polyurethane. At least one. Preferably, the polishing pad is grooved to store a polishing liquid.

The polishing conditions are not limited. In order to prevent the substrate from flying out, the upper limit of the rotation speed of the polishing platen is preferably 200 min ^-1 (rpm) or less. From the viewpoint of sufficiently suppressing the occurrence of polishing damage, the polishing applied to the substrate The upper limit of the pressure (processing load) is preferably 100 kPa or less. Preferably, the polishing liquid is continuously supplied to the polishing pad by a pump or the like during the polishing. The supply amount is not limited, and it is preferable that the surface of the polishing pad is always covered with a polishing liquid.

After polishing, the substrate is preferably sufficiently washed in running water to remove particles adhering to the substrate. In cleaning, dilute hydrofluoric acid or ammonia can be used in addition to pure water, and a brush can also be used in combination to improve the cleaning efficiency. In addition, after washing, it is preferable to use a spin dryer or the like to remove the water droplets attached to the substrate, and then dry the substrate.

The polishing liquid, the polishing liquid set, the additive liquid, and the polishing method of this embodiment can be suitably used for the formation of STI and the high-speed polishing of an interlayer insulating film. The lower limit of the polishing rate of the insulating material (for example, silicon oxide) is preferably 100 nm / minute or more, more preferably 150 nm / minute or more, and still more preferably 200 nm / minute or more.

The polishing liquid, the polishing liquid set, the additive liquid, and the polishing method of this embodiment can also be used for polishing the front metal insulating material. As the front metal insulating material, in addition to silicon oxide, for example, phosphorus-silicate glass or boron-phosphorus-silicate glass can be used, and silicon oxyfluoride or fluorinated amorphous carbon can also be used.

The polishing liquid, the polishing liquid set, the additive liquid, and the polishing method of this embodiment can also be applied to materials other than insulating materials such as silicon oxide. Examples of such materials include high dielectric constant materials such as Hf-based, Ti-based, and Ta-based oxides; semiconductor materials such as silicon, amorphous silicon, SiC, SiGe, Ge, GaN, GaP, GaAs, and organic semiconductors; GeSbTe and other phases Variable materials; inorganic conductive materials such as indium tin oxide (ITO); polymer resin materials such as polyimide-based, polybenzoxazole-based, acrylic-based, epoxy-based, and phenol-based.

The polishing liquid, polishing liquid set, additive liquid and polishing method of this embodiment can be applied not only to film-shaped polishing objects, but also to glass, silicon, SiC, SiGe, Ge, GaN, GaP, GaAs, Sapphire, plastic and other substrates.

The polishing liquid, the polishing liquid set, the additive liquid and the polishing method of this embodiment can be used not only in the manufacture of semiconductor devices, but also in thin-film transistors (TFTs) and organic electroluminescence (Electro Luminescence, EL) and other image display devices; optical components such as photomasks, lenses, chirps, optical fibers, single crystal scintillators; optical components such as light exchange elements, light waveguides; solid lasers, blue laser light emitting diodes (Light Emitting Diode (LED) and other light-emitting elements; magnetic memory devices such as magnetic disks, magnetic heads, and other manufacturing. [Example]

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

<Preparation of slurry> (Preparation of cerium hydroxide slurry) [Synthesis of hydroxide of tetravalent metal element] 350 g of a 50% by mass aqueous solution of Ce (NH ₄ ) ₂ (NO ₃ ) ₆ (Japan Chemical Industry Co., Ltd., trade name: CAN50 solution) was mixed with 7,825 g of pure water to obtain a solution. Then, while stirring the solution, 750 g of an imidazole aqueous solution (10% by mass aqueous solution, 1.47 mol / L) was added dropwise at a mixing speed of 5 mL / min, to obtain a precipitate containing cerium hydroxide. The cerium hydroxide was synthesized at a temperature of 25 ° C and a stirring speed of 400 min ^-1 . A three-vane pitch paddle with a blade length of 5 cm was used for stirring.

The obtained precipitate (precipitate containing cerium hydroxide) was subjected to centrifugal separation (4000 min ^-1 , 5 minutes), and then the liquid phase was removed by decantation to perform solid-liquid separation. After mixing 10 g of particles obtained by solid-liquid separation with 990 g of water, the particles were dispersed in water using an ultrasonic cleaner to prepare particles containing cerium hydroxide (abrasive particles. Hereinafter referred to as "cerium hydroxide" Material particles ") of the cerium hydroxide slurry (content of particles: 1.0% by mass).

[Measurement of average particle diameter] The average particle diameter (average secondary particle diameter) of the cerium hydroxide particles in the cerium hydroxide slurry was measured using a trade name: N5 manufactured by Beckman Coulter Co., Ltd. ), The result is 25 nm. The measurement method is as follows. First, about 1 mL of a 1.0% by mass measurement sample containing cerium hydroxide particles (cerium hydroxide slurry, water dispersion) was placed in a 1 cm square tank, and the tank was set in N5. The refractive index of the measurement sample information of the N5 software was set to 1.333, the viscosity was set to 0.887 mPa · s, and the measurement was performed at 25 ° C. The displayed value was read as the unimodal size mean.

[Measurement of Boundary Potential] An appropriate amount of cerium hydroxide slurry was put into a brand name: DelsaNano C manufactured by Beckman Coulter Co., Ltd., and carried out at 25 ° C for 2 Times determination. The average value of the displayed boundary potential was obtained as the boundary potential. The boundary potential of the cerium hydroxide particles in the cerium hydroxide slurry was +50 mV.

[Structure Analysis of Abrasive Particles] An appropriate amount of cerium hydroxide slurry was taken, vacuum-dried to separate the abrasive particles, and then sufficiently washed with pure water to obtain a sample. The obtained sample was measured by the FT-IR ATR method. As a result, in addition to the peak based on the hydroxide ion (OH ⁻ ), a peak based on the nitrate ion (NO 3 ⁻ ) was also observed. In addition, XPS (N-XPS) measurement for nitrogen was performed on the same sample. As a result, a peak based on NH ₄ ⁺ was not observed, and a peak based on nitrate ion was observed. From these results, it was confirmed that the abrasive grains contained in the cerium hydroxide slurry contained at least a part of particles having a nitrate ion bonded to a cerium element. In addition, when particles having hydroxide ions bonded to a cerium element were contained in at least a part of the abrasive grains, it was confirmed that the abrasive grains contained cerium hydroxide. From these results, it was confirmed that the hydroxide of cerium contains hydroxide ions bonded to the cerium element.

[Measurement of absorbance and light transmittance] A measurement sample (aqueous dispersion) was obtained by diluting an appropriate amount of cerium hydroxide slurry with water so that the abrasive grain content was 0.0065% by mass (65 ppm). About 4 mL of this measurement sample was placed in a 1 cm square tank, and the tank was set in a spectrophotometer (device name: U3310) manufactured by Hitachi, Ltd. The absorbance was measured in a range of 200 nm to 600 nm, and the absorbance of light at a wavelength of 290 nm and the absorbance of light at a wavelength of 450 to 600 nm were measured. The absorbance for light with a wavelength of 290 nm is 1.192, and the absorbance for light with a wavelength of 450 to 600 nm is less than 0.010.

Approximately 4 mL of cerium hydroxide slurry (particle content: 1.0% by mass) was placed in a 1 cm square tank, and the tank was set in a spectrophotometer (device name: U3310) manufactured by Hitachi, Ltd. . The absorbance was measured in a range of 200 nm to 600 nm, and the absorbance for light with a wavelength of 400 nm and the light transmittance for light with a wavelength of 500 nm were measured. The absorbance for light with a wavelength of 400 nm was 2.25, and the light transmittance for light with a wavelength of 500 nm was 92% / cm.

(Preparation of Cerium Oxide Slurry) [Cerium Oxide Slurry 1] 100 g of cerium dioxide particles and a trade name manufactured by Wako Pure Chemical Industries, Ltd .: polyacrylic acid 5000 (dispersant, weight average molecular weight: 5000) 1 g and 399 g of deionized water were mixed to obtain a mixed solution having a pH value of 8.0. Next, the mixed solution was subjected to ultrasonic treatment for 30 minutes while being stirred, and then the dispersion treatment was performed. Thereafter, after standing for 15 hours, the supernatant was fractionated. The solid content of the obtained supernatant was adjusted to 5.0% by mass, and a cerium oxide slurry 1 containing particles (abrasive particles. Hereinafter, referred to as "cerium oxide particles 1") containing a cerium oxide was obtained.

[Cerium oxide slurry 2] 100 g of cerium oxide particles, 0.2 g of acetic acid (dispersant) manufactured by Wako Pure Chemical Industries, Ltd., and 399.8 g of deionized water were mixed to obtain the mixed solution. Next, the mixed solution was subjected to ultrasonic treatment for 30 minutes while stirring the mixed solution to perform dispersion processing. Thereafter, after standing for 15 hours, the supernatant was fractionated. The solid content of the obtained supernatant was adjusted to 5.0% by mass to obtain a cerium oxide slurry 2 containing cerium oxide-containing particles (abrasive particles. Hereinafter, referred to as "cerium oxide particles 2").

[Measurement of average particle size] An appropriate amount of cerium oxide slurry was put into a brand name: microtrac MT3300EXII manufactured by Microtrac-bel, and the average particle diameter of cerium oxide particles was measured to obtain The displayed average particle diameter value is taken as the average particle diameter (average secondary particle diameter). The average particle diameter of the cerium oxide particles 1 in the cerium oxide slurry 1 was 340 nm. The average particle diameter of the cerium oxide particles 2 in the cerium oxide slurry 2 was 350 nm.

[Measurement of Boundary Potential] An appropriate amount of cerium oxide slurry was put into a brand name: Delsa Nano C manufactured by Beckman Coulter Co., Ltd., and performed twice at 25 ° C. Determination. The average value of the displayed boundary potential was obtained as the boundary potential. The boundary potential of the cerium oxide particles 1 in the cerium oxide slurry 1 was -55 mV. The boundary potential of the cerium oxide particles 2 in the cerium oxide slurry 2 was +50 mV.

<Preparation of polishing liquid> (Example 1A) 50.00 g of a cerium hydroxide slurry, 0.05 g of cerium (III) acetate, and 949.95 g of ion-exchanged water were mixed to prepare a cerium hydroxide containing 0.05% by mass. Particles, and a polishing solution (pH: 5.0) with 0.005 mass% of cerium (III) acetate.

(Comparative Example 1A) 50.00 g of a cerium hydroxide slurry and 950.00 g of ion-exchanged water were mixed to prepare a polishing liquid (pH: 5.0) containing 0.05% by mass of cerium hydroxide particles.

(Example 2A) 100.00 g of cerium oxide slurry 1, 0.05 g of cerium (III) acetate, and 899.95 g of ion-exchanged water were mixed to produce 0.5 mass% of cerium oxide particles 1 and 0.005 mass% Cerium (III) acetate polishing solution (pH: 7.5).

(Comparative Example 2A) 100.00 g of cerium oxide slurry 1 was mixed with 900.00 g of ion-exchanged water to prepare a polishing liquid (pH: 7.5) containing 0.5% by mass of cerium oxide particles 1.

(Comparative Example 2B) 100.00 g of cerium oxide slurry 1, 0.05 g of cerium (III) carbonate, and 899.95 g of ion-exchanged water were mixed to produce 0.5 mass% of cerium oxide particles 1 and 0.005 mass% Cerium (III) carbonate polishing solution (pH: 7.5).

(Example 3A) 100.00 g of cerium oxide slurry 2, 0.05 g of cerium (III) acetate, and 899.95 g of ion-exchanged water were mixed to produce 0.5% by mass of cerium oxide particles 2 and 0.005% by mass Cerium (III) acetate polishing solution (pH: 5.0).

(Comparative Example 3A) 100.00 g of cerium oxide slurry 2 was mixed with 900.00 g of ion-exchanged water to prepare a polishing liquid (pH: 5.0) containing 0.5% by mass of cerium oxide particles 2.

(Example 4A) 50.00 g of a cerium hydroxide slurry, 100.00 g of a cerium oxide slurry, 0.05 g of cerium (III) acetate, and 849.95 g of ion-exchanged water were mixed to prepare a solution containing 0.05% by mass. A polishing liquid (pH: 5.0) of cerium hydroxide particles, 0.5% by mass of cerium oxide particles 2, and 0.005% by mass of cerium (III) acetate.

(Comparative Example 4A) 50.00 g of cerium hydroxide slurry, 100.00 g of cerium oxide slurry 2, and 850.00 g of ion-exchanged water were mixed to produce 0.05 mass% of cerium hydroxide particles and 0.5 mass% Polishing solution of cerium oxide particles 2 (pH: 5.0).

<Evaluation of physical properties of polishing liquid> (pH value) The pH value of the polishing liquid was measured under the following conditions. Measuring temperature: 25 ± 5 ℃ Measuring device: manufactured by Electric Chemical Instrument Co., Ltd. Model PHL-40 Measuring method: Use standard buffer solution (phthalate pH buffer solution, pH value: 4.01 (25 ℃); Neutral phosphate pH buffer solution, pH value: 6.86 (25 ° C)) After performing two-point calibration, put the electrode in the polishing solution, and measure the pH value stabilized by the measuring device after more than 2 minutes. .

(Average Particle Size of Abrasive Particles) The measurement of the abrasive particles (cerium hydroxide particles) in the abrasive liquid of Example 1A and Comparative Example 1A using the trade name: N5 manufactured by Beckman Coulter Co., Ltd. was performed. Average particle size (average secondary particle size). The average particle diameter in Example 1A and Comparative Example 1A was 10 nm.

Trade name manufactured by Microtrac-bel: Microtrac MT3300EXII is put into a proper amount of Example 2A, Example 3A, Example 4A and Comparative Example 2A, Comparative Example 2B, Comparative Example 3A, Comparison In the polishing liquid of Example 4A, the average particle diameter of the abrasive particles was measured, and the average particle diameter shown was obtained as the average particle diameter (average secondary particle diameter). The average particle diameter of Example 2A, Comparative Example 2A, and Comparative Example 2B was 340 nm, and the average particle diameter of Example 3A and Comparative Example 3A was 350 nm. The average particle diameter of Example 4A and Comparative Example 4A was 355 nm.

(Boundary Potential of Abrasive Particles) An appropriate amount of polishing liquid was put into a brand name: Delsa Nano C manufactured by Beckman Coulter Co., Ltd., and measurement was performed twice at 25 ° C. The average value of the displayed boundary potential was obtained as the boundary potential.

<CMP Evaluation> Using each of the polishing liquids, the substrate to be polished was polished under the following polishing conditions.

(Polishing conditions) Polishing device: F-REX300 (manufactured by Ebara Manufacturing Co., Ltd.) Polishing liquid flow rate: 200 mL / minute Substrate to be polished: As a blanket wafer without pattern, it is used on a silicon substrate Polishing substrate polishing pad for silicon oxide film with a thickness of 2 μm formed by plasma CVD method: foamed polyurethane resin with closed cells (manufactured by Rohm And Haas Japan Co., Ltd., Model IC1010) Grinding pressure: 20 kPa (2.9 psi) The number of revolutions of the substrate to be polished and the polishing platen: substrate to be polished / platen = 93/87 rpm Grinding time: 0.5 minutes (30 seconds) Wafer cleaning: at After the CMP treatment, the substrate was washed with water while applying an ultrasonic wave, and then dried with a spin dryer.

(Evaluation of polishing rate) The polishing rate of the silicon oxide film (polishing rate of the silicon oxide film: SiO ₂ RR) in the substrate to be polished which was polished and cleaned under the above conditions was determined by the following formula. The film thickness difference of the silicon oxide film before and after polishing was determined using a light interference film thickness measuring device (produced by FILMETRICS, trade name: F80). Polishing speed (RR) = (film thickness difference [nm] of silicon oxide film before and after polishing) / (polishing time 0.5 [minute])

In order to confirm the effect of improving the polishing rate by a water-soluble compound containing a trivalent rare-earth element, the polishing rate A based on the example using the water-soluble compound containing a trivalent rare-earth element was compared with a case where the polishing rate A was not used. In the polishing rate B of the comparative example of the water-soluble compound, the increase rate of the polishing rate of the following formula was calculated. In Table 2, the polishing rate of Comparative Example 2A was used as the polishing rate B. Increasing rate of grinding speed (%) = (grinding speed A-grinding speed B) / grinding speed B × 100

The results obtained in the examples and comparative examples are shown in Tables 1 to 4.

[Table 1]

[Table 2]

[table 3]

[Table 4]

As shown in the respective tables, in the examples, it was confirmed that the polishing rate of the insulating material was improved as compared with the comparative example in which the water-soluble compound containing a trivalent rare earth element was not used.

no

FIG. 1 is a schematic diagram showing a state in which abrasive particles are aggregated when an additive is added. FIG. 2 is a schematic diagram showing a state in which abrasive particles are aggregated when an additive is added.

Claims (18)

A polishing liquid contains abrasive particles, a water-soluble compound containing a trivalent rare earth element, and a liquid medium, and the content of the water-soluble compound exceeds 0% by mass and less than 0.05% by mass. The polishing liquid according to item 1 of the scope of patent application, wherein the content of the abrasive particles exceeds 0% by mass and is 1.5% by mass or less. The polishing liquid according to item 1 or 2 of the patent application scope, wherein the abrasive particles include a cerium compound. The polishing liquid according to item 3 of the patent application scope, wherein the cerium compound comprises a cerium hydroxide. The polishing liquid according to item 3 or 4 of the scope of patent application, wherein the cerium compound contains a cerium oxide. The polishing liquid according to any one of claims 1 to 5, in which the abrasive particles include a hydroxide of a tetravalent metal element. The polishing liquid according to any one of claims 1 to 6, in which the boundary potential of the abrasive particles is positive. The polishing liquid according to any one of claims 1 to 6 in the scope of the patent application, wherein the boundary potential of the abrasive particles is negative. The polishing liquid according to any one of claims 1 to 8 in the scope of the patent application, wherein the absolute value of the boundary potential of the abrasive particles is 10 mV or more. The polishing liquid according to any one of claims 1 to 9, in which the trivalent rare earth element of the water-soluble compound contains cerium. The polishing liquid according to any one of claims 1 to 10, wherein the water-soluble compound is selected from the group consisting of cerium nitrate, cerium ammonium nitrate, cerium chloride, cerium phosphate, cerium sulfate, and cerium acetate. At least one of the groups. The polishing liquid according to any one of claims 1 to 11 in the scope of the patent application, which does not contain a tetravalent rare earth element (except for the components contained in the polishing particles) as an active ingredient. The polishing liquid according to any one of the items 1 to 12 of the scope of patent application, wherein the content of the oxidant is less than 0.05% by mass. The polishing liquid according to any one of claims 1 to 13 in the scope of patent application, wherein the pH value is 2.0 to 10.0. The polishing liquid according to any one of claims 1 to 14 of the scope of patent application, which is used for polishing a surface to be polished containing silicon oxide. A polishing liquid set, which is configured by dividing the constituent components of the polishing liquid according to any one of claims 1 to 15 of a patent application scope into a first liquid and a second liquid, and storing the first liquid. The abrasive particles and a liquid medium are included, and the second liquid includes the water-soluble compound and a liquid medium. An additive liquid for mixing with a liquid containing the abrasive particles to obtain an additive liquid according to any one of claims 1 to 15 of the scope of patent application, and the additive liquid contains Said water-soluble compound and liquid medium. A polishing method comprising using a polishing liquid as described in any one of claims 1 to 15 in the patent application scope, or a polishing solution set as described in claim 16 on the patent application scope A polishing liquid obtained by mixing one liquid with the second liquid, and polishing the surface to be polished;