JPWO2019182061A1 - Polishing liquid, polishing liquid set and polishing method - Google Patents

Abstract

The polymer compound contains an abrasive grain, a hydroxy acid, a polymer compound having at least one selected from the group consisting of a hydroxyl group and an amide group, and a liquid medium, and the zeta potential of the abrasive grains is positive. A polishing liquid having a weight average molecular weight of 3000 or more.

Description

The present invention relates to a polishing liquid, a polishing liquid set, and a polishing method.

In recent years, in the manufacturing process of semiconductor devices, the importance of processing technology for high density and miniaturization is increasing. CMP (Chemical Mechanical Polishing) technology, which is one of the processing technologies, is the formation of shallow trench isolation (shallow trench isolation, hereinafter referred to as "STI") in the manufacturing process of semiconductor devices. It is an indispensable technology for flattening pre-metal insulating materials or interlayer isolation materials, and for forming plugs or embedded metal wiring.

Examples of the most frequently used polishing liquid include silica-based polishing liquid containing silica (silicon oxide) particles such as fumed silica and colloidal silica as abrasive grains. The silica-based polishing liquid is characterized by high versatility, and a wide variety of materials can be polished regardless of the insulating material and the conductive material by appropriately selecting the abrasive grain content, pH, additives and the like.

On the other hand, as a polishing liquid mainly for insulating materials such as silicon oxide, there is an increasing demand for a polishing liquid containing cerium compound particles as abrasive grains. For example, a cerium oxide-based polishing solution containing cerium oxide particles as abrasive grains can polish silicon oxide at a higher speed even with a lower abrasive grain content than a silica-based polishing solution (see, for example, Patent Documents 1 and 2 below).

Japanese Unexamined Patent Publication No. 10-106994 Japanese Unexamined Patent Publication No. 08-022970

In recent years, polishing scratches generated during polishing have become a problem in the manufacturing process of semiconductor devices. Methods for reducing polishing scratches include a method of reducing the content of abrasive grains during polishing, a method of reducing the size of abrasive grains (for example, a method of reducing coarse particles of 1 μm or more), and a method of reducing the load during polishing. The method and the like can be mentioned. However, these methods have a problem that the polishing speed of the insulating material is lowered because the mechanical action at the time of polishing is reduced.

Therefore, in recent years, abrasive grains having a positive zeta potential (cationic abrasive grains) have begun to be used in order to increase the reactivity between the abrasive grains and the insulating material and improve the polishing rate. In comparison of abrasive grains having the same size, abrasive grains having a positive zeta potential tend to have a higher polishing rate of the insulating material than abrasive grains having a negative zeta potential. However, when abrasive grains having a positive zeta potential are used, there is a problem that the abrasive grains tend to remain on the surface to be polished after polishing, resulting in poor detergency. Abrasive grains remaining on the surface to be polished after polishing are one of the causes of lowering the yield of the device as well as polishing scratches. Therefore, for a polishing liquid containing abrasive grains having a positive zeta potential, it is required to have excellent cleanability of the surface to be polished after polishing.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a polishing liquid, a polishing liquid set, and a polishing method having excellent cleanability of the surface to be polished after polishing.

The polishing liquid according to one aspect of the present invention contains abrasive grains, hydroxyic acid, a polymer compound having at least one selected from the group consisting of hydroxyl groups and amide groups, and a liquid medium. The zeta potential is positive, and the weight average molecular weight of the polymer compound is 3000 or more.

With such a polishing liquid, it is possible to prevent the abrasive grains from remaining on the surface to be polished after polishing, and the surface to be polished after polishing is excellent in cleanability. According to such a polishing liquid, the yield of the device can be improved by reducing the residual abrasive grains after polishing.

In the polishing liquid set according to the other aspect of the present invention, the constituent components of the above-mentioned polishing liquid are separately stored as a first liquid and a second liquid, and the first liquid is the abrasive grains and the abrasive grains. It contains a liquid medium, and the second liquid contains the hydroxy acid, the polymer compound, and the liquid medium. According to such a polishing liquid set, the same effect as the above-mentioned polishing liquid can be obtained.

The polishing method according to another aspect of the present invention uses the above-mentioned polishing liquid or a polishing liquid obtained by mixing the first liquid and the second liquid in the above-mentioned polishing liquid set. It is provided with a polishing process for polishing the polished surface. According to such a polishing method, the same effect as the above-mentioned polishing liquid can be obtained.

According to the present invention, it is possible to provide a polishing liquid having excellent cleanability of the surface to be polished after polishing. According to the present invention, it is possible to provide a polishing liquid set for obtaining the polishing liquid. According to the present invention, it is possible to provide a polishing method using the polishing liquid or the polishing liquid set.

According to the present invention, it is possible to provide the use of a polishing liquid or a polishing liquid set for a process of flattening a surface of a substrate. According to the present invention, it is possible to provide the use of a polishing liquid or a polishing liquid set for a flattening step of an STI insulating material, a premetal insulating material or an interlayer insulating material.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

<Definition>
In the present specification, the numerical range indicated by using "~" indicates a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively. In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value of the numerical range of one step can be arbitrarily combined with the upper limit value or the lower limit value of the numerical range of another step. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "A or B" may include either A or B, or both. Unless otherwise specified, the materials exemplified in the present specification may be used alone or in combination of two or more. In the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means. The term "process" is included in this term not only in an independent process but also in the case where the desired action of the process is achieved even if it cannot be clearly distinguished from other processes.

As used herein, a "polishing liquid" (abrasive) is defined as a composition that comes into contact with the surface to be polished during polishing. The phrase "polishing liquid" itself does not limit the components contained in the polishing liquid. As will be described later, the polishing liquid according to this embodiment contains abrasive grains. Abrasive particles are also referred to as "abrasive particles", but are referred to as "abrasive particles" in the present specification. Abrasive particles are generally solid particles, and are to be removed by the mechanical action (physical action) of the abrasive grains and the chemical action of the abrasive grains (mainly the surface of the abrasive grains) during polishing. It is believed that the object will be removed, but not limited to this.

<Abrasive liquid and polishing liquid set>
The polishing liquid according to this embodiment is, for example, a polishing liquid for CMP. The polishing liquid according to the present embodiment contains abrasive grains, a hydroxy acid, and a polymer compound containing at least one selected from the group consisting of a hydroxyl group (hydroxyl group) and an amide group (hereinafter referred to as “polymer compound A”). , The liquid medium, the zeta potential of the abrasive grains is positive, and the weight average molecular weight of the polymer compound A is 3000 or more.

According to the present embodiment, it is possible to prevent the abrasive grains from remaining on the surface to be polished after polishing, and the cleanability of the surface to be polished after polishing (hereinafter, in some cases, simply referred to as "cleanability"). Excellent for. According to this embodiment, the yield of the device can be improved by reducing the residual abrasive grains after polishing. According to this embodiment, the abrasive grains can be removed by using an alkaline solution such as ammonia without using a toxic substance such as hydrofluoric acid to remove the abrasive grains from the surface to be polished after polishing. Reasons for obtaining such excellent detergency include, for example, the following reasons. However, the reason is not limited to the following.

That is, when the polymer compound A containing at least one selected from the group consisting of hydroxyl groups and amide groups comes into contact with abrasive grains having a positive zeta potential, the value of the zeta potential becomes small. When the weight average molecular weight of the polymer compound A is 3000 or more, the zeta potential value tends to be small because the polymer compound A easily covers the abrasive grains. In this case, the adsorptivity (reactivity) of the abrasive grains to the insulating material which tends to have a negative charge tends to decrease.
Further, by using the polymer compound A, the wettability of the surface to be polished with respect to the cleaning liquid used in the cleaning step is improved. Further, when a hydroxy acid is used, the hydrophilic acid is adsorbed on the abrasive grains to improve the hydrophilicity, so that the affinity between the abrasive grains and the cleaning liquid is improved.
Based on the above, it is presumed that according to the present embodiment, excellent cleaning properties can be obtained because the abrasive grains are easily removed in the cleaning step after polishing.

Further, according to the present embodiment, the wettability of the polishing pad and the surface to be polished with respect to the polishing liquid is improved by using the polymer compound A. As a result, the polishing liquid does not easily stay between the polishing pad and the surface to be polished, so that the amount of abrasive grains remaining after the completion of polishing can be reduced as compared with the case where the polymer compound A is not used.

According to this embodiment, it is possible to obtain excellent detergency while obtaining an excellent polishing rate. Further, according to the present embodiment, as a method of reducing polishing scratches, a method of reducing the content of abrasive grains during polishing and a method of reducing the size of abrasive grains (for example, a method of reducing coarse particles of 1 μm or more). ), Even when a method of reducing the load during polishing is used, excellent cleanability can be obtained while reducing polishing scratches and obtaining an excellent polishing rate.

(Abrasive grain)
The polishing liquid according to the present embodiment contains abrasive grains having a positive zeta potential in the polishing liquid. Abrasive grains are made from cerium oxide (for example, cerium (cerium oxide (IV))), silica, alumina, zirconia, yttria, and hydroxides of tetravalent metal elements from the viewpoint of easy polishing of insulating materials at high polishing rates. It is preferable to contain at least one selected from the above group, and it is more preferable to contain cerium oxide. The abrasive grains may be used alone or in combination of two or more.

The "hydroxide of a tetravalent metal element" is a compound containing a ^{tetravalent metal (M 4+} ) and at least one hydroxide ion (OH ^−). Hydroxides of tetravalent metal elements, anions other than hydroxide ion (e.g., nitrate ion NO ₃ ^- and sulfate ions SO 4 ^_2-) may contain. For example, hydroxides of tetravalent metal elements, tetravalent metallic element bound anions (e.g., nitrate ion NO ₃ ^- and sulfate ions SO 4 ^_2-) may contain. A hydroxide of a tetravalent metal element can be produced by reacting a salt (metal salt) of the tetravalent metal element with an alkali source (base).

The hydroxide of the tetravalent metal element preferably contains cerium hydroxide (hydroxide of tetravalent cerium) from the viewpoint of easily improving the polishing rate of the insulating material. Cerium hydroxide can be produced by reacting a cerium salt with an alkali source (base). The cerium hydroxide is preferably prepared by mixing a cerium salt and an alkaline solution (for example, an alkaline aqueous solution). As a result, particles having an extremely fine particle size can be obtained, and an excellent effect of reducing polishing scratches can be easily obtained. The cerium hydroxide can be obtained by mixing a cerium salt solution (for example, a cerium salt aqueous solution) and an alkaline solution. Examples of the cerium salt include Ce (NO ₃ ) ₄ , Ce (SO ₄ ) ₂ , Ce (NH ₄ ) ₂ (NO ₃ ) ₆ , Ce (NH ₄ ) ₄ (SO ₄ ) _{4, and the} like.

^{Ce (Ce 4+} ) consisting of tetravalent cerium (Ce 4+), 1 to 3 hydroxide ions (OH ⁻ ) and 1 to 3 anions (X ^c −), depending on the production conditions of cerium hydroxide. OH) _{It is considered that particles containing a} X _b (in the formula, a + b × c = 4) are produced (note that such particles are also cerium hydroxides). In Ce (OH) _a X _b , electron-withdrawing anions (X ^c- ) act to improve the reactivity of hydroxide ions, and the abundance of _{Ce (OH) a} X _{b increases.} It is considered that the polishing speed is improved accordingly. The anion ^{(X c-),} for example, NO ₃ ^- and _SO ^{4 2-and} the like. It is considered that the particles containing cerium hydroxide may contain _{not only Ce (OH) a} X _b but also Ce (OH) ₄ , CeO _{2, and the} like.

The fact that the particles containing cerium hydroxide contain Ce (OH) _a X _b means that the particles are thoroughly washed with pure water, and then the FT-IR ATR method (Fourier transform InfraRed Spectrometriated Total Reflection method, Fourier transform infrared) is used. It can be confirmed by a method of detecting a peak corresponding to ^{an anion (Xc-} ) by a spectrophotometer total reflection measurement method). The XPS method (X-ray Photoelectron Spectroscopy, X-ray photoelectron spectroscopy), it is also possible to confirm the presence of an anion ^{(X c-).}

When the abrasive grains contain cerium oxide, the lower limit of the content of cerium oxide is based on the entire abrasive grains (the entire abrasive grains contained in the polishing liquid; the same applies hereinafter) from the viewpoint of further improving the polishing rate of the insulating material. It is preferably 50% by mass or more, more preferably more than 50% by mass, further preferably 60% by mass or more, particularly preferably 70% by mass or more, extremely preferably 80% by mass or more, and very preferably 90% by mass or more. Preferably, 95% by mass or more is more preferable, 98% by mass or more is more preferable, and 99% by mass or more is further preferable. These numerical ranges may be satisfied in an embodiment in which the abrasive grains do not contain composite particles described later.

The lower limit of the average particle size of the abrasive grains in the polishing liquid or the polishing liquid set described later is preferably 16 nm or more, more preferably 20 nm or more, and more preferably 30 nm or more from the viewpoint of easily improving the polishing speed of the insulating material. More preferably, 40 nm or more is particularly preferable, 50 nm or more is extremely preferable, 50 nm or more is very preferable, 100 nm or more is even more preferable, 120 nm or more is more preferable, and 140 nm or more is further preferable. The upper limit of the average particle size of the abrasive grains is preferably 1050 nm or less, more preferably 1000 nm or less, further preferably 800 nm or less, particularly preferably 600 nm or less, and particularly preferably 500 nm or less, from the viewpoint of easily suppressing damage to the surface to be polished. Is extremely preferable, 400 nm or less is very preferable, 300 nm or less is further preferable, 200 nm or less is more preferable, 160 nm or less is further preferable, and 155 nm or less is particularly preferable. From these viewpoints, the average particle size of the abrasive grains is more preferably 16 to 50 nm, and further preferably 20 to 1000 nm.

The average particle size is measured using, for example, a light diffraction / scattering type particle size distribution meter (for example, manufactured by Beckman Coulter Co., Ltd., trade name: N5, or manufactured by Microtrack Bell Co., Ltd., trade name: Microtrack MT3300EXII). can do.

The zeta potential (surface potential) of the abrasive grains in the polishing liquid is positive from the viewpoint of excellent cleanability of the surface to be polished after polishing (the abrasive grains are suppressed from remaining on the surface to be polished after polishing). (Zeta potential exceeds 0 mV). The lower limit of the zeta potential of the abrasive grains is preferably 10 mV or more, more preferably 20 mV or more, further preferably 25 mV or more, particularly preferably 30 mV or more, extremely preferably 40 mV or more, and extremely preferably 50 mV from the viewpoint that excellent detergency can be easily obtained. The above is very preferable. The upper limit of the zeta potential of the abrasive grains is not particularly limited, but is preferably 200 mV or less. From these viewpoints, the zeta potential of the abrasive grains is more preferably 10 to 200 mV.

The zeta potential of the abrasive grains can be measured using, for example, a dynamic light scattering type zeta potential measuring device (for example, manufactured by Beckman Coulter, Inc., trade name: DelsaNano C). The zeta potential of the abrasive grains can be adjusted with an additive. For example, by bringing a monocarboxylic acid (for example, acetic acid) into contact with abrasive grains containing cerium oxide, abrasive grains having a positive zeta potential can be obtained. Further, by bringing ammonium dihydrogen phosphate, a material having a carboxyl group (for example, polyacrylic acid), or the like into contact with the abrasive grains containing cerium oxide, abrasive grains having a negative zeta potential can be obtained.

The lower limit of the content of abrasive grains is preferably 0.005% by mass or more, and more preferably more than 0.005% by mass, based on the total mass of the polishing liquid, from the viewpoint of easily improving the polishing speed of the insulating material. , 0.01% by mass or more is more preferable, 0.02% by mass or more is particularly preferable, 0.03% by mass or more is extremely preferable, 0.04% by mass or more is very preferable, and 0.05% by mass or more is more. More preferably, 0.07% by mass or more is more preferable, and 0.1% by mass or more is further preferable. The upper limit of the content of abrasive grains is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less, based on the total mass of the polishing liquid, from the viewpoint that excellent detergency can be easily obtained. Preferably, 5% by mass or less is particularly preferable, 4% by mass or less is extremely preferable, 3% by mass or less is very preferable, 1% by mass or less is further preferable, 0.5% by mass or less is more preferable, and 0.3% by mass is preferable. % Or less is more preferable, and 0.2% by mass or less is particularly preferable. From these viewpoints, the content of abrasive grains is more preferably 0.005 to 20% by mass based on the total mass of the polishing liquid.

The abrasive grains may include composite particles composed of a plurality of particles in contact with each other. For example, the abrasive grains may include composite particles containing a first particle and a second particle in contact with the first particle, and the composite particle and free particles (eg, contact with the first particle). It may contain a second particle) which is not.

The abrasive grains include, as an embodiment containing composite particles, a first particle and a second particle in contact with the first particle, and the particle size of the second particle is larger than the particle size of the first particle. The first particle may contain a cerium oxide, and the second particle may contain a cerium compound. By using such abrasive grains, it is easy to improve the polishing speed of the insulating material (for example, silicon oxide). Reasons for improving the polishing speed of the insulating material in this way include, for example, the following reasons. However, the reason is not limited to the following.

That is, the first particle containing cerium oxide and having a particle size larger than that of the second particle has a stronger mechanical action (mechanical property) on the insulating material than the second particle. On the other hand, the second particle, which contains a cerium compound and has a particle size smaller than that of the first particle, has a smaller mechanical action on the insulating material than the first particle, but has a specific surface area of the entire particle. Since (surface area per unit mass) is large, it has a strong chemical action (chemical property) on the insulating material. As described above, the synergistic effect of improving the polishing speed can be easily obtained by using the first particle having a strong mechanical action and the second particle having a strong chemical action in combination.

Examples of the cerium compound of the second particle include cerium hydroxide and cerium oxide. As the cerium compound of the second particle, a compound different from the cerium oxide can be used. The cerium compound preferably contains a cerium hydroxide from the viewpoint of easily improving the polishing rate of the insulating material.

The particle size of the second particle is preferably smaller than the particle size of the first particle. The magnitude relationship between the particle sizes of the first particles and the second particles can be determined from the SEM image of the composite particles and the like. In general, particles having a small particle size have a higher surface area per unit mass than particles having a large particle size, and therefore have higher reaction activity. On the other hand, the mechanical action (mechanical polishing force) of the particles having a small particle size is smaller than that of the particles having a large particle size. However, in the present embodiment, even when the particle size of the second particle is smaller than the particle size of the first particle, it is possible to exhibit the synergistic effect of the first particle and the second particle. Therefore, excellent reaction activity and mechanical action can be easily compatible with each other.

The lower limit of the particle size of the first particles is preferably 15 nm or more, more preferably 25 nm or more, further preferably 35 nm or more, particularly preferably 40 nm or more, and extremely preferably 50 nm or more from the viewpoint of easily improving the polishing rate of the insulating material. Preferably, 80 nm or more is very preferable, and 100 nm or more is even more preferable. The upper limit of the particle size of the first particle is preferably 1000 nm or less, more preferably 800 nm or less, and more preferably 600 nm from the viewpoint of easily obtaining excellent detergency and easily suppressing damage to the surface to be polished. The following is further preferable, 400 nm or less is particularly preferable, 300 nm or less is extremely preferable, 200 nm or less is very preferable, and 150 nm or less is even more preferable. From these viewpoints, the particle size of the first particles is more preferably 15 to 1000 nm. The average particle size (average secondary particle size) of the first particles may be in the above range.

The lower limit of the particle size of the second particles is preferably 1 nm or more, more preferably 2 nm or more, still more preferably 3 nm or more, from the viewpoint of easily improving the polishing rate of the insulating material. The upper limit of the particle size of the second particle is preferably 50 nm or less, more preferably 30 nm or less, and more preferably 25 nm from the viewpoint of easily obtaining excellent detergency and easily suppressing damage to the surface to be polished. The following is more preferable, 20 nm or less is particularly preferable, 15 nm or less is extremely preferable, and 10 nm or less is very preferable. From these viewpoints, the particle size of the second particle is more preferably 1 to 50 nm. The average particle size (average secondary particle size) of the second particles may be in the above range.

The first particle can have a negative zeta potential. The second particle can have a positive zeta potential.

As the abrasive grains, in an embodiment containing the above-mentioned composite particles and free particles, a water dispersion (a mixture of abrasive grains and water) in which the content of the abrasive grains is adjusted to 1.0% by mass is centrifuged at 5.8. It is preferable to provide a liquid phase (supernatant) having an absorbance of more than 0 for light having a wavelength of 380 nm when centrifuged at × 10 ^{4 G for 5 minutes.} In this case, it is easy to improve the polishing rate of the insulating material (for example, silicon oxide).

Reasons for improving the polishing speed in this way include, for example, the following reasons. However, the reason is not limited to the following.
That is, when the absorbance of the liquid phase obtained by centrifuging the aqueous dispersion with respect to light having a wavelength of 380 nm exceeds 0, the composite particles are easily selectively removed by such centrifugation, and the free particles are separated into solids. When it is possible to obtain a liquid phase containing as, and the absorbance exceeds 0, the abrasive grains include free particles in addition to the composite particles. Since the free particles have a smaller particle size than the composite particles, they have a high diffusion rate and preferentially adsorb to the surface of the insulating material to cover the surface. In this case, the composite particles can act not only directly on the insulating material but also on the free particles adsorbed on the insulating material and indirectly act on the insulating material (for example, adsorbed on the insulating material). Physical action can be transmitted to the insulating material through the free particles). It is presumed that this makes it easier to improve the polishing speed of the insulating material.

The above-mentioned absorbance with respect to light having a wavelength of 380 nm is preferably in the following range. The lower limit of the absorbance is preferably 0.001 or more, more preferably 0.0015 or more, still more preferably 0.002 or more, from the viewpoint of further improving the polishing rate of the insulating material. When the content of free particles is high, the amount of free particles adsorbed on the insulating material increases, so it is presumed that the polishing rate of the insulating material can be further improved. The upper limit of the absorbance is preferably 0.5 or less, more preferably 0.4 or less, further preferably 0.3 or less, and particularly preferably 0.25 or less, from the viewpoint of further improving the polishing rate of the insulating material. 0.2 or less is extremely preferable. From the above viewpoint, the absorbance is more preferably more than 0 and 0.5 or less. The absorbance can be adjusted by adjusting the content of free particles in the abrasive grains. For example, increasing the surface area of the first particle that the second particle comes into contact with, or adjusting the dispersion state to be insufficient when the first particle and the second particle are brought into contact with each other (decreasing the dispersion time). The absorbance can be reduced by reducing the number of rotations in stirring the liquid containing the first particles and the second particles, weakening the electrostatic repulsive force generated between the particles, and the like.

In the present embodiment, the abrasive grains having the above-mentioned absorbance of light having a wavelength of 380 nm of 0 may be used. Such abrasive grains can be obtained by removing free particles by centrifugation.

The abrasive grains are an aqueous dispersion (mixture consisting of abrasive grains and water) in which the content of the abrasive grains is adjusted to 1.0% by mass from the viewpoint of further improving the polishing speed of the insulating material (for example, silicon oxide). When centrifuged at a centrifugal acceleration of 5.8 × 10 ⁴ G for 5 minutes, it is preferable to provide a liquid phase (supernatant) having a light transmittance in the following range with respect to light having a wavelength of 500 nm. The lower limit of the light transmittance is preferably 50% / cm or more, more preferably 60% / cm or more, further preferably 70% / cm or more, particularly preferably 80% / cm or more, and extremely preferably 90% / cm or more. Preferably, 92% / cm or more is very preferable. The upper limit of light transmittance is 100% / cm.

The first particle and the composite particle containing the second particle are brought into contact with the first particle and the second particle by using a homogenizer, a nanomizer, a ball mill, a bead mill, an ultrasonic processing machine or the like, and the charge opposite to each other. It can be obtained by bringing the first particle and the second particle into contact with each other, or by bringing the first particle and the second particle into contact with each other in a state where the content of the particles is low.

The lower limit of the content of cerium oxide in the first particles is the whole of the first particles (the whole of the first particles contained in the polishing liquid; the same applies hereinafter) from the viewpoint of easily improving the polishing rate of the insulating material. As a reference, 50% by mass or more is preferable, 70% by mass or more is more preferable, 90% by mass or more is further preferable, and 95% by mass or more is particularly preferable. The first particle may be in a mode substantially composed of cerium oxide (a mode in which 100% by mass of the first particle is substantially cerium oxide).

The lower limit of the content of the cerium compound in the second particles is based on the whole of the second particles (the whole of the second particles contained in the polishing liquid; the same applies hereinafter) from the viewpoint of easily improving the polishing rate of the insulating material. As a result, 50% by mass or more is preferable, 70% by mass or more is more preferable, 90% by mass or more is further preferable, and 95% by mass or more is particularly preferable. The second particle may be in a mode substantially composed of a cerium compound (a mode in which 100% by mass of the second particle is substantially a cerium compound).

The content of the second particle can be estimated from the value of the absorbance of the following formula obtained by the spectrophotometer when light of a specific wavelength is transmitted through the polishing liquid. That is, when the particles absorb light of a specific wavelength, the light transmittance of the region containing the particles decreases. The light transmittance is reduced not only by absorption by the particles but also by scattering, but in the second particle, the influence of scattering is small. Therefore, in the present embodiment, the content of the second particle can be estimated from the value of the absorbance calculated by the following formula.
Absorbance = -LOG ₁₀ (light transmittance [%] / 100)

The content of the first particles in the abrasive grains containing the composite particles is preferably in the following range with respect to the entire abrasive grains. The lower limit of the content of the first particles is preferably 50% by mass or more, more preferably more than 50% by mass, further preferably 60% by mass or more, and 70% by mass from the viewpoint of easily improving the polishing rate of the insulating material. % Or more is particularly preferable, 75% by mass or more is extremely preferable, 80% by mass or more is very preferable, 85% by mass or more is even more preferable, and 90% by mass or more is more preferable. The upper limit of the content of the first particles is preferably 95% by mass or less, more preferably 93% by mass or less, still more preferably 91% by mass or less, from the viewpoint of easily improving the polishing rate of the insulating material. From these viewpoints, the content of the first particles is more preferably 50 to 95% by mass.

The content of the second particles in the abrasive grains containing the composite particles is preferably in the following range with respect to the entire abrasive grains. The lower limit of the content of the second particles is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 9% by mass or more, from the viewpoint of easily improving the polishing rate of the insulating material. The upper limit of the content of the second particles is preferably 50% by mass or less, more preferably less than 50% by mass, further preferably 40% by mass or less, and 30% by mass or less from the viewpoint of easily improving the polishing rate of the insulating material. Is particularly preferable, 25% by mass or less is extremely preferable, 20% by mass or less is very preferable, 15% by mass or less is even more preferable, and 10% by mass or less is more preferable. From these viewpoints, the content of the second particle is more preferably 5 to 50% by mass.

The content of cerium oxide in the abrasive grains containing the composite particles is preferably in the following range with respect to the entire abrasive grains. The lower limit of the content of the cerium oxide is preferably 50% by mass or more, more preferably more than 50% by mass, further preferably 60% by mass or more, and even more preferably 70% by mass, from the viewpoint of easily improving the polishing rate of the insulating material. The above is particularly preferable, 75% by mass or more is extremely preferable, 80% by mass or more is very preferable, 85% by mass or more is further preferable, and 90% by mass or more is more preferable. The upper limit of the content of the cerium oxide is preferably 95% by mass or less, more preferably 93% by mass or less, still more preferably 91% by mass or less, from the viewpoint of easily improving the polishing rate of the insulating material. From these viewpoints, the content of cerium oxide is more preferably 50 to 95% by mass.

The content of cerium hydroxide in the abrasive grains containing the composite particles is preferably in the following range with respect to the entire abrasive grains. The lower limit of the content of the cerium hydroxide is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 9% by mass or more, from the viewpoint of easily improving the polishing rate of the insulating material. The upper limit of the content of cerium hydroxide is preferably 50% by mass or less, more preferably less than 50% by mass, further preferably 40% by mass or less, and 30% by mass or less from the viewpoint of easily improving the polishing rate of the insulating material. Is particularly preferable, 25% by mass or less is extremely preferable, 20% by mass or less is very preferable, 15% by mass or less is even more preferable, and 10% by mass or less is more preferable. From these viewpoints, the content of cerium hydroxide is more preferably 5 to 50% by mass.

The content of the first particle is preferably in the following range based on the total amount of the first particle and the second particle. The lower limit of the content of the first particles is preferably 50% by mass or more, more preferably more than 50% by mass, further preferably 60% by mass or more, and 70% by mass from the viewpoint of easily improving the polishing rate of the insulating material. % Or more is particularly preferable, 75% by mass or more is extremely preferable, 80% by mass or more is very preferable, 85% by mass or more is even more preferable, and 90% by mass or more is more preferable. The upper limit of the content of the first particles is preferably 95% by mass or less, more preferably 93% by mass or less, still more preferably 91% by mass or less, from the viewpoint of easily improving the polishing rate of the insulating material. From these viewpoints, the content of the first particles is more preferably 50 to 95% by mass.

The content of the second particle is preferably in the following range based on the total amount of the first particle and the second particle. The lower limit of the content of the second particles is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 9% by mass or more, from the viewpoint of easily improving the polishing rate of the insulating material. The upper limit of the content of the second particles is preferably 50% by mass or less, more preferably less than 50% by mass, further preferably 40% by mass or less, and 30% by mass or less from the viewpoint of easily improving the polishing rate of the insulating material. Is particularly preferable, 25% by mass or less is extremely preferable, 20% by mass or less is very preferable, 15% by mass or less is even more preferable, and 10% by mass or less is more preferable. From these viewpoints, the content of the second particle is more preferably 5 to 50% by mass.

The content of the first particles in the polishing liquid is preferably in the following range based on the total mass of the polishing liquid. The lower limit of the content of the first particles is preferably 0.005% by mass or more, more preferably 0.008% by mass or more, and further preferably 0.01% by mass or more from the viewpoint of easily improving the polishing rate of the insulating material. Preferably, 0.05% by mass or more is particularly preferable, 0.08% by mass or more is extremely preferable, and 0.09% by mass or more is very preferable. The upper limit of the content of the first particles is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and 0.5% by mass, from the viewpoint of easily increasing the storage stability of the polishing liquid. It is particularly preferably 0% by mass or less, extremely preferably 0.3% by mass or less, very preferably 0.2% by mass or less, and even more preferably 0.1% by mass or less. From these viewpoints, the content of the first particles is more preferably 0.005 to 5% by mass.

The content of the second particles in the polishing liquid is preferably in the following range based on the total mass of the polishing liquid. The lower limit of the content of the second particles is preferably 0.005% by mass or more from the viewpoint that the chemical interaction between the abrasive grains and the surface to be polished is further improved and the polishing speed of the insulating material is easily improved. 0.008% by mass or more is more preferable, and 0.009% by mass or more is further preferable. The upper limit of the content of the second particle makes it easy to avoid agglomeration of abrasive grains, and further improves the chemical interaction between the abrasive grains and the surface to be polished, effectively utilizing the characteristics of the abrasive grains. From the viewpoint of easy operation, 5% by mass or less is preferable, 3% by mass or less is more preferable, 1% by mass or less is further preferable, 0.5% by mass or less is particularly preferable, 0.1% by mass or less is extremely preferable, and 0. 05% by mass or less is very preferable, 0.04% by mass or less is further preferable, 0.035% by mass or less is more preferable, 0.03% by mass or less is further preferable, and 0.02% by mass or less is particularly preferable. 0.01% by mass or less is extremely preferable. From these viewpoints, the content of the second particle is more preferably 0.005 to 5% by mass.

The content of cerium oxide in the polishing liquid containing abrasive grains containing composite particles is preferably in the following range based on the total mass of the polishing liquid. The lower limit of the content of cerium oxide is preferably 0.005% by mass or more, more preferably 0.008% by mass or more, still more preferably 0.01% by mass or more, from the viewpoint of easily improving the polishing rate of the insulating material. , 0.05% by mass or more is particularly preferable, 0.08% by mass or more is extremely preferable, and 0.09% by mass or more is very preferable. The upper limit of the content of the cerium oxide is preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 1% by mass or less, and 0.5% by mass from the viewpoint of easily increasing the storage stability of the polishing liquid. % Or less is particularly preferable, 0.3% by mass or less is extremely preferable, 0.2% by mass or less is very preferable, and 0.1% by mass or less is even more preferable. From these viewpoints, the content of cerium oxide is more preferably 0.005 to 5% by mass.

The content of cerium hydroxide in the polishing liquid containing abrasive grains containing composite particles is preferably in the following range based on the total mass of the polishing liquid. The lower limit of the content of cerium hydroxide is preferably 0.005% by mass or more from the viewpoint that the chemical interaction between the abrasive grains and the surface to be polished is further improved and the polishing speed of the insulating material is easily improved. 0.008% by mass or more is more preferable, and 0.009% by mass or more is further preferable. The upper limit of the content of cerium hydroxide facilitates avoiding agglomeration of abrasive grains and further improves the chemical interaction between the abrasive grains and the surface to be polished, effectively utilizing the characteristics of the abrasive grains. From the viewpoint of easy easiness, 5% by mass or less is preferable, 3% by mass or less is more preferable, 1% by mass or less is further preferable, 0.5% by mass or less is particularly preferable, 0.1% by mass or less is extremely preferable, and 0. 05% by mass or less is very preferable, 0.04% by mass or less is further preferable, 0.035% by mass or less is more preferable, 0.03% by mass or less is further preferable, and 0.02% by mass or less is particularly preferable. 0.01% by mass or less is extremely preferable. From these viewpoints, the content of cerium hydroxide is more preferably 0.005 to 5% by mass.

(Additive)
The polishing liquid according to this embodiment contains an additive. Here, the "additive" refers to a substance contained in the polishing liquid in addition to the abrasive grains and the liquid medium.

[Hydroxy acids]
The polishing liquid according to this embodiment contains a hydroxy acid (excluding the compound corresponding to the polymer compound A). Hydroxy acids have at least one carboxyl group and at least one hydroxyl group. The "hydroxyl group" does not include "-OH" in the carboxyl group. The "hydroxyl group" may be either an alcoholic hydroxyl group or a phenolic hydroxyl group. Hydroxy acids do not have to have phenolic hydroxyl groups.

The hydroxy acid preferably has one carboxyl group and 1 to 3 hydroxyl groups (for example, alcoholic hydroxyl groups) from the viewpoint that excellent detergency can be easily obtained. The number of hydroxyl groups of the hydroxy acid is preferably 1 to 2 and more preferably 2 from the viewpoint that excellent detergency can be easily obtained. The number of hydroxyl groups of the hydroxy acid may be 2 to 3.

As the hydroxy acid, glycolic acid, glyceric acid, lactic acid (for example, DL-lactic acid), 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butyric acid, 2-hydroxyisobutyric acid (also known as:: 2-Methyllactic acid), N, N-bis (2-hydroxyethyl) glycine, N- [2-hydroxy-1,1-bis (hydroxymethyl) ethyl] glycine, bicin, tricin, tyrosine, serine, threonine, etc. Can be mentioned. Hydroxy acids include lactic acid (for example, DL-lactic acid), 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butyric acid, and N from the viewpoint of obtaining excellent detergency and polishing rate. , N-bis (2-hydroxyethyl) glycine, and at least one selected from the group consisting of N- [2-hydroxy-1,1-bis (hydroxymethyl) ethyl] glycine, preferably 2,2. It is more preferable to contain at least one selected from the group consisting of −bis (hydroxymethyl) propionic acid and 2,2-bis (hydroxymethyl) butyric acid, and further to contain 2,2-bis (hydroxymethyl) propionic acid. preferable.

The hydroxy acid preferably contains an aliphatic hydroxy acid from the viewpoint that excellent detergency can be easily obtained. The hydroxy acid may contain a hydroxy acid containing a nitrogen atom, or may contain a hydroxy acid containing no nitrogen atom. The hydroxy acid may have an amino group and may not have an amino group. Hydroxy acids may or may not contain amino acids.

The polishing liquid according to this embodiment may contain a hydroxy acid other than a hydroxy acid having one carboxyl group and 1 to 3 hydroxyl groups. Examples of such a hydroxy acid include a hydroxy acid having two or more carboxyl groups and a hydroxy acid having four or more hydroxyl groups. Specific examples include glucuronic acid, gluconic acid, citric acid, tartaric acid and the like.

The upper limit of the hydroxyl value of the hydroxy acid is preferably 1500 or less, more preferably 1300 or less, further preferably 1100 or less, particularly preferably 1000 or less, and extremely preferably 900 or less, from the viewpoint that excellent detergency can be easily obtained. The lower limit of the hydroxyl value of the hydroxy acid is preferably 50 or more, more preferably 150 or more, further preferably 250 or more, particularly preferably 500 or more, extremely preferably 600 or more, and 650, from the viewpoint that excellent detergency can be easily obtained. The above is very preferable. From these viewpoints, the hydroxyl value of the hydroxy acid is more preferably 50 to 1500. The "hydroxyl value" is a numerical value that is an index of the number of hydroxyl groups contained in the hydroxy acid, and is calculated from the following formula (1).
Hydroxy group value = 56110 x number of hydroxyl groups / molecular weight ... (1)

The lower limit of the hydroxy acid content is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, based on the total mass of the polishing liquid, from the viewpoint of easily obtaining excellent detergency. 005% by mass or more is further preferable, 0.008% by mass or more is particularly preferable, 0.01% by mass or more is extremely preferable, 0.03% by mass or more is very preferable, 0.05% by mass or more is even more preferable. 0.08% by mass or more is more preferable, 0.1% by mass or more is further preferable, 0.2% by mass or more is particularly preferable, 0.3% by mass or more is extremely preferable, and 0.4% by mass or more is very preferable. .. The upper limit of the content of the hydroxy acid is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, based on the total mass of the polishing liquid, from the viewpoint that an excellent polishing rate can be easily obtained. More preferably, it is 5% by mass or less. From these viewpoints, the content of the hydroxy acid is more preferably 0.001 to 1.0% by mass, still more preferably 0.01 to 1.0% by mass, based on the total mass of the polishing liquid.

The lower limit of the content of the hydroxy acid is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further 30 parts by mass or more with respect to 100 parts by mass of the abrasive grains from the viewpoint that excellent detergency can be easily obtained. It is preferable, and 40 parts by mass or more is particularly preferable. The upper limit of the content of the hydroxy acid is preferably 100 parts by mass or less, more preferably less than 100 parts by mass, and further 80 parts by mass or less with respect to 100 parts by mass of the abrasive grains from the viewpoint that an excellent polishing rate can be easily obtained. Preferably, 70 parts by mass or less is particularly preferable, 60 parts by mass or less is extremely preferable, and 50 parts by mass or less is very preferable. From these viewpoints, the content of the hydroxy acid is more preferably 10 to 100 parts by mass with respect to 100 parts by mass of the abrasive grains.

The lower limit of the content of a hydroxy acid having one carboxyl group and 1 to 3 hydroxyl groups is 50 based on the total mass of the hydroxy acid contained in the polishing liquid from the viewpoint that excellent detergency can be easily obtained. Mass% or more is preferable, 70% by mass or more is more preferable, 90% by mass or more is further preferable, 95% by mass or more is particularly preferable, 97% by mass or more is extremely preferable, and 99% by mass or more is very preferable.

[Polymer compound A]
The polishing liquid according to this embodiment contains a polymer compound A having at least one selected from the group consisting of a hydroxyl group and an amide group. As the polymer compound A, a water-soluble polymer can be used. The "water-soluble polymer" is defined as a polymer that dissolves 0.1 g or more in 100 g of water (the same applies hereinafter).

The polymer compound A preferably contains a polyol as the polymer compound having a hydroxyl group from the viewpoint that excellent detergency can be easily obtained. A polyol is a compound having two or more hydroxyl groups in the molecule. Since it is easy to form a protective layer on the surface to be polished and to gently adjust the polishing rate of the polymer compound A, overpolishing of the recesses is easily suppressed, and the wafer after polishing is finished flat. From the viewpoint of ease of use, a polyether polyol (a polymer compound having a polyether structure) may be included as the polymer compound having a hydroxyl group.

Examples of the polymer compound A having a hydroxyl group include polyglycerin, polyvinyl alcohol, polyalkylene glycol (polyethylene glycol, etc.), polyoxyalkylene glycol, polyoxyalkylene sorbitol ether (polyoxypropylene sorbitol ether, etc.), and polyoxyalkylene condensation of ethylenediamine. Things (ethylenediamine tetrapolyoxyethylene polyoxypropylene, etc.), 2,2-bis (4-polyoxyalkylene-oxyphenyl) propane, polyoxyalkylene glyceryl ether, polyoxyalkylene diglyceryl ether, polyoxyalkylene trimethyl propane ether , Polyoxyalkylene pentaerythritol ether, polyoxyalkylene methyl glucoside and the like.

Examples of the polymer compound A having an amide group include polyvinylpyrrolidone, poly-N-vinylacetamide and the like. The polymer compound A can have at least one selected from the group consisting of a primary amide group, a secondary amide group and a tertiary amide group. The polymer compound A preferably contains a compound having a secondary amide group from the viewpoint of easily obtaining excellent detergency and polishing rate. The polymer compound A preferably contains a compound having a tertiary amide group from the viewpoint of easily obtaining excellent detergency and polishing rate.

The polymer compound A preferably contains a compound having a polyoxyalkylene structure. As a result, it is easier to form a protective layer on the surface to be polished to gently adjust the polishing rate, so that over-polishing of the recesses can be more easily suppressed, and the polished wafer can be finished flat. It's even easier. The carbon number of the oxyalkylene group (structural unit) in the polyoxyalkylene structure is preferably 1 or more, and more preferably 2 or more, from the viewpoint that excellent detergency can be easily obtained. The carbon number of the oxyalkylene group (structural unit) in the polyoxyalkylene structure is preferably 5 or less, more preferably 4 or less, still more preferably 3 or less, from the viewpoint that excellent detergency can be easily obtained. From these viewpoints, the carbon number is preferably 1 to 5. The polyoxyalkylene chain may be a homopolymerized chain or a copolymerized chain. The copolymer chain may be a block polymerized chain or a random polymerized chain.

The polymer compound A may satisfy at least one of the following characteristics from the viewpoint that excellent detergency can be easily obtained. The number of hydroxyl groups of the polymer compound A may be 4 or less, may be 3 or less, and may be 1 or 2. The polymer compound A may be a chain compound. The polymer compound A may contain a homopolymer of a monomer having at least one selected from the group consisting of a hydroxyl group and an amide group. The polymer compound A does not have to have a structural unit derived from glucose. The polymer compound A may contain a compound having a hydroxyl group only in the side chain. The polymer compound A may contain a compound having a plurality of structural units having a hydroxyl group. The polymer compound A may contain two or more compounds having the same structural unit having a hydroxyl group. The polymer compound A may contain a compound having a plurality of structural units having an amide group. The polymer compound A may contain two or more compounds having the same structural unit having an amide group. The amide group in these structural units may be at least one selected from the group consisting of a primary amide group, a secondary amide group and a tertiary amide group. The polymer compound A may contain a compound having a side chain containing an amide group, and has a main chain containing a carbon chain or a polyoxyalkylene chain, and a side chain bonded to the main chain and containing an amide group. May include compounds. The polymer compound A may contain a compound having a main chain containing a hydroxyl group at both ends, and may contain a compound having a carbon chain containing a hydroxyl group or a polyoxyalkylene chain at both ends. As the "main chain", the longest molecular chain among the molecular chains constituting the polymer compound can be used.

The polymer compound A preferably contains at least one selected from the group consisting of polyvinyl alcohol, polyalkylene glycol, polyvinylpyrrolidone, and poly-N-vinylacetamide from the viewpoint of easily obtaining excellent detergency. The polymer compound A preferably contains a polymer compound having no aromatic group from the viewpoint that excellent detergency can be easily obtained.

The lower limit of the weight average molecular weight of the polymer compound A is 3000 or more from the viewpoint of excellent cleanability of the surface to be polished after polishing (suppression of abrasive grains remaining on the surface to be polished after polishing). The lower limit of the weight average molecular weight of the polymer compound A is preferably 4000 or more, more preferably 5000 or more, further preferably 6000 or more, particularly preferably 8000 or more, and extremely preferably 10000 or more from the viewpoint that excellent detergency can be easily obtained. preferable. The upper limit of the weight average molecular weight of the polymer compound A is preferably 1,000,000 or less, more preferably 750000 or less, further preferably 500,000 or less, particularly preferably 400,000 or less, and extremely preferably 200,000 or less from the viewpoint that excellent detergency can be easily obtained. Preferably, 100,000 or less is very preferable, 50,000 or less is even more preferable, 30,000 or less is more preferable, and 20,000 or less is further preferable. From these viewpoints, the weight average molecular weight of the polymer compound A is more preferably 3000 to 1,000,000.

When the polymer compound A has a hydroxyl group, the lower limit of the weight average molecular weight of the polymer compound A is preferably the following range in addition to the above-mentioned range of the weight average molecular weight from the viewpoint that excellent detergency can be easily obtained. The weight average molecular weight of the polymer compound A is preferably more than 10,000, more preferably 12,000 or more, further preferably 15,000 or more, particularly preferably 18,000 or more, and extremely preferably 20,000 or more.

When the polymer compound A has an amide group, the upper limit of the weight average molecular weight of the polymer compound A is preferably the following range in addition to the above-mentioned range of the weight average molecular weight from the viewpoint that excellent detergency can be easily obtained. The weight average molecular weight of the polymer compound A is preferably 15,000 or less, more preferably 12,000 or less, and even more preferably 10,000 or less.

The weight average molecular weight of the polymer compound A can be measured, for example, by gel permeation chromatography (GPC) using a standard polystyrene calibration curve under the following conditions.
Equipment used: Hitachi L-6000 type [manufactured by Hitachi, Ltd.]
Column: Gelpack GL-R420 + Gelpack GL-R430 + Gelpack GL-R440 [Product name manufactured by Hitachi Kasei Co., Ltd., 3 in total]
Eluent: tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 mL / min
Detector: L-3300RI [manufactured by Hitachi, Ltd.]

The content of the polymer compound A is preferably in the following range based on the total mass of the polishing liquid. The lower limit of the content of the polymer compound A is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, still more preferably 0.05% by mass or more, from the viewpoint that excellent detergency can be easily obtained. , 0.08% by mass or more is particularly preferable, and 0.1% by mass or more is extremely preferable. The lower limit of the content of the polymer compound A is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.4% by mass or more, from the viewpoint that an excellent polishing rate can be easily obtained. , 0.5% by mass or more is particularly preferable. The lower limit of the content of the polymer compound A is preferably 0.6% by mass or more, more preferably 0.8% by mass or more, and further preferably 1.0% by mass or more, from the viewpoint that particularly excellent detergency can be easily obtained. preferable. The upper limit of the content of the polymer compound A is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and 2.0% by mass or less from the viewpoint of easily obtaining excellent detergency and polishing speed. Is more preferable, and 1.0% by mass or less is particularly preferable. From these viewpoints, the content of the polymer compound A is more preferably 0.01 to 5.0% by mass, and further preferably 0.05 to 5.0% by mass.

The mass ratio of the content of the polymer compound A to the content of the abrasive grains (content of the polymer compound A / content of the abrasive grains) is preferably in the following range. The lower limit of the mass ratio is preferably 0.1 or more, more preferably 0.3 or more, further preferably 0.5 or more, particularly preferably 0.8 or more, from the viewpoint that excellent detergency can be easily obtained. The above is extremely preferable. The lower limit of the mass ratio is preferably 2 or more, more preferably 3 or more, further preferably 4 or more, and particularly preferably 5 or more, from the viewpoint that an excellent polishing rate can be easily obtained. The lower limit of the mass ratio is preferably 6 or more, more preferably 8 or more, still more preferably 10 or more, from the viewpoint that particularly excellent detergency can be easily obtained. The upper limit of the mass ratio is preferably 50 or less, more preferably 30 or less, still more preferably 10 or less, from the viewpoint that excellent detergency and polishing speed can be easily obtained. From these viewpoints, the mass ratio is more preferably 0.1 to 50.

The mass ratio of the content of the polymer compound A to the content of the hydroxy acid (content of the polymer compound A / content of the hydroxy acid) is preferably in the following range. The lower limit of the mass ratio is preferably 0.01 or more, more preferably 0.05 or more, further preferably 0.1 or more, particularly preferably 0.2 or more, and 0, from the viewpoint that excellent detergency can be easily obtained. .25 or more is extremely preferable. The lower limit of the mass ratio is preferably 0.3 or more, more preferably 0.5 or more, further preferably 1 or more, and particularly preferably 1.25 or more, from the viewpoint that an excellent polishing rate can be easily obtained. The lower limit of the mass ratio is preferably 1.5 or more, more preferably 2 or more, and even more preferably 2.5 or more, from the viewpoint that particularly excellent detergency can be easily obtained. The upper limit of the mass ratio is preferably 10 or less, more preferably 5 or less, still more preferably 2.5 or less, from the viewpoint of easily obtaining excellent detergency and polishing speed. From these viewpoints, the mass ratio is more preferably 0.01 to 10.

[Any additive]
The polishing liquid according to the present embodiment may contain any additive (excluding the compound corresponding to the hydroxy acid or the polymer compound A). Examples of the optional additive include a water-soluble polymer, an oxidizing agent (for example, hydrogen peroxide), a dispersant (for example, a phosphoric acid-based inorganic salt) and the like. Examples of the water-soluble polymer include polyacrylic acid-based polymers such as polyacrylic acid, polyacrylic acid copolymer, polyacrylic acid salt, and polyacrylic acid copolymer salt; and polymethacrylic acid such as polymethacrylic acid and polymethacrylic acid salt. Examples include acid-based polymers.

(Liquid medium)
The liquid medium in the polishing liquid according to the present embodiment is not particularly limited, but water such as deionized water and ultrapure water is preferable. The content of the liquid medium may be the balance of the polishing liquid excluding the content of other constituent components, and is not particularly limited.

(Characteristics of polishing liquid)
The lower limit of the pH of the polishing liquid according to the present embodiment makes it easy to obtain excellent detergency (for example, the electrostatic attraction between the abrasive grains and the insulating material is increased by lowering the absolute value of the positive zeta potential of the abrasive grains. From the viewpoint of (easy to reduce), 2.0 or more is preferable, 2.5 or more is more preferable, 3.0 or more is further preferable, 3.2 or more is particularly preferable, 3.4 or more is extremely preferable, and 3.5 or more is extremely preferable. Is very preferable, and 4.0 or more is even more preferable. The upper limit of pH is preferably 8.0 or less, more preferably less than 8.0, further preferably 7.5 or less, particularly preferably 7.0 or less, and 6.5 or less, from the viewpoint that excellent detergency can be easily obtained. The following is extremely preferable, 6.0 or less is very preferable, and 5.0 or less is even more preferable. From these viewpoints, the pH of the polishing liquid is more preferably 2.0 to 8.0, and even more preferably 2.0 to 7.0. The pH may be less than 3.0, 2.8 or less, and 2.5 or less. The pH of the polishing liquid is defined as the pH at a liquid temperature of 25 ° C.

The pH of the polishing solution is an acid component such as an inorganic acid or an organic acid; an alkaline component such as ammonia, sodium hydroxide, tetramethylammonium hydroxide (TMAH), imidazole, alkanolamine, pyrazole (for example, 3,5-dimethylpyrazole). It can be adjusted by such as. A buffer may be added to stabilize the pH. A buffer may be added as a buffer (a solution containing a buffer). Examples of such a buffer solution include an acetate buffer solution and a phthalate buffer solution.

The pH of the polishing liquid according to this embodiment can be measured with a pH meter (for example, model number PHL-40 manufactured by DKK-TOA CORPORATION). Specifically, for example, after calibrating a pH meter at two points using a phthalate pH buffer solution (pH: 4.01) and a neutral phosphate pH buffer solution (pH: 6.86) as standard buffer solutions. , Put the electrode of the pH meter in the polishing solution, and measure the value after it stabilizes after 2 minutes or more. The temperature of both the standard buffer solution and the polishing solution shall be 25 ° C.

The polishing liquid according to the present embodiment may be stored as a one-component polishing liquid containing at least abrasive grains, a hydroxy acid, a polymer compound A, and a liquid medium, and may be stored as a slurry (first liquid). The components of the polishing liquid are stored as a multi-component (for example, two-component) polishing liquid set in which the constituent components of the polishing liquid are divided into a slurry and an additive liquid so as to be mixed with the additive liquid (second liquid) to become the polishing liquid. You may. That is, the constituent components of the polishing liquid may be stored separately as a slurry and an additive liquid. The slurry contains, for example, abrasive grains and at least a liquid medium. The additive liquid contains, for example, at least a hydroxy acid, a polymer compound A, and a liquid medium. The hydroxy acid, the polymer compound A, any additive, and the buffer are preferably contained in the additive solution among the slurry and the additive solution. The constituent components of the polishing liquid may be stored as 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 at the time of polishing to prepare a polishing liquid. Further, the one-component polishing liquid may be stored as a storage liquid for a polishing liquid in which the content of the liquid medium is reduced, and may be diluted with a liquid medium at the time of polishing and used. The multi-liquid type polishing liquid set is stored as a storage liquid for slurry and a storage liquid for additive liquid in which the content of the liquid medium is reduced, and may be diluted with a liquid medium at the time of polishing and used.

<Polishing method>
The polishing method (method for polishing the substrate, etc.) according to the present embodiment uses the one-component polishing liquid or the polishing liquid obtained by mixing the slurry and the additive liquid in the polishing liquid set, and uses the surface to be polished (the polishing liquid). It may be provided with a polishing step for polishing the surface to be polished of the substrate, etc.). The surface to be polished may contain an insulating material and may contain silicon oxide. The insulating material may have a negative zeta potential.

The lower limit of the polishing rate of the insulating material (for example, silicon oxide) is preferably 170 nm / min or more, more preferably 180 nm / min or more, further preferably 200 nm / min or more, particularly preferably 250 nm / min or more, and particularly preferably 270 nm / min or more. Extremely preferable.

According to the present embodiment, it is possible to provide the use of a polishing liquid or a polishing liquid set in a polishing step of selectively polishing an insulating material with respect to a stopper material. Examples of the stopper material include silicon nitride and polysilicon.

The polishing method according to the present embodiment may be a polishing method for a substrate having an insulating material and silicon nitride. For example, the one-component polishing solution or the slurry and the additive solution in the polishing solution set are mixed. It may be provided with a polishing step of selectively polishing the insulating material with respect to silicon nitride by using the polishing liquid obtained above. In this case, the substrate may have, for example, a member containing an insulating material and a member containing silicon nitride.

The polishing method according to the present embodiment may be a polishing method for a substrate having an insulating material and polysilicon. For example, the one-component polishing liquid or the slurry and the additive liquid in the polishing liquid set are mixed. It may be provided with a polishing step of selectively polishing the insulating material with respect to polysilicon by using the polishing liquid obtained above. In this case, the substrate may have, for example, a member containing an insulating material and a member containing polysilicon.

The polishing method according to the present embodiment may be a method for polishing a substrate having a first member including a stopper material and a second member containing an insulating material and arranged on the first member. The polishing step is a step of polishing the second member until the first member is exposed by using the one-component polishing solution or the polishing solution obtained by mixing the slurry and the additive solution in the polishing solution set. You may have. In the polishing step, after the first member is exposed, the first member and the second member use the one-component polishing solution or the polishing solution obtained by mixing the slurry and the additive solution in the polishing solution set. May have a step of polishing.

"Selectively polishing the material A with respect to the material B" means that the polishing speed of the material A is higher than the polishing speed of the material B under the same polishing conditions. More specifically, for example, it means polishing the material A when the polishing rate ratio of the polishing rate of the material A to the polishing rate of the material B is 80 or more.

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

Examples of the substrate to be polished include a substrate to be polished. Examples of the substrate to be polished include a substrate in which a material to be polished is formed on a substrate (for example, a semiconductor substrate on which an STI pattern, a gate pattern, a wiring pattern, etc. are formed) related to manufacturing a semiconductor element. Examples of the material to be polished include insulating materials such as silicon oxide (excluding materials corresponding to stopper materials); stopper materials such as polysilicon and silicon nitride. The material to be polished may be a single material or a plurality of materials. When a plurality of materials are exposed on the surface to be polished, they can be regarded as the materials to be polished. The material to be polished may be in the form of a film (film to be polished), or may be a silicon oxide film, a polysilicon film, a silicon nitride film, or the like.

By polishing the material to be polished (for example, an insulating material such as silicon oxide) formed on such a substrate with the polishing liquid and removing excess portions, the unevenness of the surface of the material to be polished is eliminated. A smooth surface can be obtained over the entire surface of the material to be polished. The polishing liquid according to this embodiment is preferably used for polishing the surface to be polished containing an insulating material. The polishing liquid according to this embodiment is preferably used for polishing the surface to be polished containing silicon oxide.

In the present embodiment, the substrate has an insulating material containing at least silicon oxide on the surface, a stopper (polishing stop layer) arranged under the insulating material, and a substrate (semiconductor substrate or the like) arranged under the stopper. The insulating material can be polished. The stopper material constituting the stopper is a material having a lower polishing rate than the insulating material, and silicon nitride, polysilicon, and the like are preferable. In such a substrate, by stopping the polishing when the stopper is exposed, it is possible to prevent the insulating material from being excessively polished, so that the flatness of the insulating material after polishing can be improved.

As a method for producing a material to be polished by the polishing liquid according to the present embodiment, a CVD method such as a low pressure CVD method, a quasi-normal pressure CVD method, a plasma CVD method, etc.; a rotary coating method in which a liquid raw material is applied to a rotating substrate. And so on.

Hereinafter, the polishing method according to the present embodiment will be described by taking as an example a method for polishing a substrate (for example, a substrate having an insulating material formed on a semiconductor substrate). In the polishing method according to the present embodiment, as the polishing apparatus, a general polishing apparatus having a holder capable of holding a substrate having a surface to be polished and a polishing surface plate to which a polishing pad can be attached can be used. A motor or the like whose rotation speed can be changed is attached to each of the holder and the polishing surface plate. As the polishing device, for example, a polishing device: Reflection manufactured by Applied Materials can be used.

As the polishing pad, a general non-woven fabric, foam, non-foam or the like can be used. Materials for the polishing pad include polyurethane, acrylic resin, polyester, acrylic-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly4-methylpentene, cellulose, cellulose ester, and polyamide (for example, nylon (trade name)). And aramid), polyimide, polyimideamide, polysiloxane copolymer, oxylan compound, phenol resin, polystyrene, polycarbonate, epoxy resin and other resins can be used. As the material of the polishing pad, at least one selected from the group consisting of foamed polyurethane and non-foamed polyurethane is preferable from the viewpoint of further excellent polishing speed and flatness. It is preferable that the polishing pad is grooved so that the polishing liquid can be collected.

Although there is no limit to the polishing conditions, the upper limit of the rotational speed of the polishing platen is preferably ^200min -1 ^(min -1 = rpm) or less so as not fly out is base, the upper limit of the polishing pressure (working load) applied to the substrate Is preferably 15 psi (103 kPa) or less from the viewpoint of sufficiently suppressing the occurrence of polishing scratches. During polishing, it is preferable to continuously supply the polishing liquid to the polishing pad with a pump or the like. There is no limit to the amount of this supply, but it is preferable that the surface of the polishing pad is always covered with the polishing liquid.

The polishing method according to the present embodiment may further include a cleaning step of bringing an alkaline solution (cleaning solution) into contact with the surface to be polished after the polishing step. In the cleaning step, the surface to be polished can be cleaned by bringing the alkaline solution into contact with the surface to be polished. In the cleaning step, the surface to be polished can be cleaned by removing the abrasive grains adhering to the surface to be polished in the polishing step. Ammonia, TMAH (tetramethylammonium hydroxide), or the like can be used as the alkaline source of the alkaline solution. In the cleaning step, hydrofluoric acid, ammonia-hydrogen peroxide mixed solution, hydrochloric acid-hydrogen peroxide mixed solution, sulfuric acid-hydrogen peroxide mixed solution and the like do not have to be brought into contact with the surface to be polished.

In the cleaning step, a brush may be used in combination to improve the cleaning efficiency. Further, after cleaning, it is preferable to use a spin dryer or the like to remove water droplets adhering to the substrate and then dry the substrate.

This embodiment can also be used for polishing a premetal insulating material. Examples of the premetal insulating material include silicon oxide, phosphorus-silicate glass, boron-phosphorus-silicate glass, silicon oxyfluorolide, and amorphous carbon fluoride.

This embodiment can 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 the like. Phase change material; Inorganic conductive material such as ITO; Polyimide-based, polybenzoxazole-based, acrylic-based, epoxy-based, phenol-based and other polymer resin materials and the like can be mentioned.

This embodiment can be applied not only to a film-like polishing target but also to various substrates composed of glass, silicon, SiC, SiCe, Ge, GaN, GaP, GaAs, sapphire, plastic and the like.

In this embodiment, not only the manufacture of semiconductor elements, but also image display devices such as TFTs and organic ELs; optical components such as photomasks, lenses, prisms, optical fibers, and single crystal scintillators; optical elements such as optical switching elements and optical waveguides. Light emitting elements such as solid-state lasers and blue laser LEDs; can be used in the manufacture of magnetic storage devices such as magnetic disks and magnetic heads.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the following examples.

<Making abrasive grains>
(Preparation of cerium oxide particles)
40 kg of commercially available cerium carbonate hydrate was placed in an alumina container and calcined in air at 830 ° C. for 2 hours to obtain 20 kg of a yellowish white powder. The phase identification of this powder was performed by X-ray diffraction method, and it was confirmed that a cerium oxide powder was obtained. 20 kg of the obtained cerium oxide powder was dry-pulverized using a jet mill to obtain a cerium oxide powder containing cerium oxide particles.

(Preparation of composite particles)
[Preparation of cerium oxide slurry]
The cerium oxide powder and Wako Pure Chemical Industries, Ltd. trade name: ammonium dihydrogen phosphate (molecular weight: 97.99) are mixed to obtain 5.0 cerium oxide particles (first particles). A cerium oxide slurry (pH: 7) containing mass% (solid content) was prepared. The blending amount of ammonium dihydrogen phosphate was adjusted to 1% by mass based on the total amount of cerium oxide particles.

Trade name manufactured by Microtrac Bell Co., Ltd .: An appropriate amount of cerium oxide slurry was put into Microtrac MT3300EXII, and the average particle size of the cerium oxide particles was measured. The displayed average particle size value was obtained as the average particle size (average secondary particle size). The average particle size of the cerium oxide particles in the cerium oxide slurry was 145 nm.

A suitable amount of cerium oxide slurry was put into DelsaNano C, a trade name manufactured by Beckman Coulter Co., Ltd., and the measurement was carried out twice at 25 ° C. The average value of the displayed zeta potentials was obtained as the zeta potentials. The zeta potential of the cerium oxide particles in the cerium oxide slurry was -55 mV.

[Preparation of cerium hydroxide slurry]
480g of _{Ce (NH 4) 2 (NO} 3) 6 50 % by weight aqueous solution (Nihon Kagaku Sangyo Co., Ltd., trade name: CAN 50 solution) to obtain a solution by mixing with pure water 7450G. Then, while stirring this solution, 750 g of an imidazole aqueous solution (10 mass% aqueous solution, 1.47 mol / L) was added dropwise at a mixing rate of 5 mL / min to obtain a precipitate containing cerium hydroxide. The synthesis of cerium hydroxide was carried out at a temperature of 20 ° C. and a stirring speed of 500 min- ^1. Stirring was performed using a 3-blade pitch paddle having a blade length of 5 cm.

The obtained precipitate (precipitate containing cerium hydroxide) was centrifuged (4000 ^{min -1} , 5 minutes), and then solid-liquid separation was performed by removing the liquid phase by decantation. After mixing 10 g of the particles obtained by solid-liquid separation and 990 g of water, the particles are dispersed in water using an ultrasonic washing machine, and cerium containing cerium hydroxide particles (second particles) is dispersed. A hydroxide slurry (particle content: 1.0% by mass) was prepared.

The average particle size (average secondary particle size) of the cerium hydroxide particles in the cerium hydroxide slurry manufactured by Beckman Coulter Co., Ltd. and trade name: N5 was measured and found to be 10 nm. The measurement method is as follows. First, about 1 mL of a measurement sample (cerium hydroxide slurry, aqueous dispersion) containing 1.0% by mass of cerium hydroxide particles was placed in a 1 cm square cell, and then the cell was placed in N5. The refractive index of the measurement sample information of the software of N5 was set to 1.333 and the viscosity was set to 0.887 mPa · s, the measurement was performed at 25 ° C., and the value displayed as Unimodal Size Mean was read.

A suitable amount of cerium hydroxide slurry was put into DelsaNano C, a trade name manufactured by Beckman Coulter Co., Ltd., and the measurement was carried out twice at 25 ° C. The average value of the displayed zeta potentials was obtained as the zeta potentials. The zeta potential of the cerium hydroxide particles in the cerium hydroxide slurry was +50 mV.

An appropriate amount of cerium hydroxide slurry was collected, vacuum dried to isolate cerium hydroxide particles, and then thoroughly washed with pure water to obtain a sample. The obtained sample was subjected to measurement by FT-IR ATR method, hydroxide ions ^- in addition to the peak based on the nitrate ion (OH) (NO ₃ ^-) peak based on was observed. Further, for the same sample, it was subjected to XPS (N-XPS) measurement for nitrogen, a peak based on NH ₄ ⁺ is not observed, a peak based on nitrate ions was observed. From these results, it was confirmed that the cerium hydroxide particles contained at least a part of the particles having nitrate ions bonded to the cerium element. Further, since particles having hydroxide ions bonded to the cerium element are contained in at least a part of the cerium hydroxide particles, it was confirmed that the cerium hydroxide particles contain the cerium hydroxide. From these results, it was confirmed that the hydroxide of cerium contains hydroxide ions bonded to the element of cerium.

<Measurement of absorbance and light transmittance of supernatant>
The absorbance and light transmittance given by the abrasive grains used in Example 9 described later in the supernatant were measured.

The cerium hydroxide slurry and deionized water were mixed to obtain a mixed solution while stirring at a rotation speed of 300 rpm using a two-blade stirring blade. Subsequently, the cerium oxide slurry is mixed with the mixed solution while stirring the mixed solution, and then ultrasonic waves are irradiated using an ultrasonic cleaner (device name: US-105) manufactured by SND Co., Ltd. Stirred. As a result, in addition to the composite particles containing the cerium oxide particles and the cerium hydroxide particles in contact with the cerium oxide particles, the cerium hydroxide particles (free particles) not in contact with the cerium oxide particles. A test slurry (content of cerium oxide particles: 0.1% by mass, content of cerium hydroxide particles: 0.01% by mass) containing the above was prepared.

A test solution was prepared by adjusting the content of abrasive particles (total amount of particles) in the test slurry to 0.1% by mass (diluted with ion-exchanged water). 7.5 g of the test solution was placed in a centrifuge (trade name: Optima MAX-TL) manufactured by Beckman Coulter Co., Ltd., ^{and the supernatant was treated at a centrifugal acceleration of 5.8 × 10 4} G and a set temperature of 25 ° C. for 5 minutes. Got

After putting about 4 mL of the supernatant into a 1 cm square quartz cell, the cell was placed in a spectrophotometer (device name: U3310) manufactured by Hitachi, Ltd. The absorbance was measured in the wavelength range of 200 to 600 nm, and the absorbance value at the wavelength of 380 nm was read from the obtained chart. The absorbance was 0.002. Moreover, when the value of the light transmittance at a wavelength of 500 nm was read from the obtained chart, it was 92% / cm or more.

<Preparation of polishing liquid for CMP>
(Examples 1 to 8 and 10 to 13 and Comparative Examples 1 to 2)
The cerium oxide powder (cerium oxide particles) and deionized water were mixed to obtain a mixed solution. Next, the hydroxy acids shown in Table 1 or Table 2 (Comparative Example 2 was not added), the polymer compound and the pH adjuster (3,5-dimethylpyrazole) were mixed with the mixed solution. Then, by performing ultrasonic dispersion while stirring, the total mass of the polishing liquid for CMP is reduced to 0.1% by mass of the cerium oxide particles, 0.4% by mass of the hydroxy acid, and 0.1% by mass of the pH adjuster. In addition, a polishing liquid for CMP containing the polymer compounds having the contents shown in Table 1 or Table 2 was obtained. The ultrasonic dispersion was performed at an ultrasonic frequency of 400 kHz and a dispersion time of 30 minutes.

As the polyethylene glycol having a weight average molecular weight of 4000, the trade name "polyethylene glycol 4000" manufactured by Wako Pure Chemical Industries, Ltd. was used. As the polyethylene glycol having a weight average molecular weight of 20000, the trade name "polyethylene glycol 20000" manufactured by Wako Pure Chemical Industries, Ltd. was used. As the polyvinyl alcohol, the trade name "polyvinyl alcohol" manufactured by Wako Pure Chemical Industries, Ltd. was used. As the poly-N-vinylacetamide, the trade name "poly-N-vinylacetamide" manufactured by Showa Denko KK was used. As the polyvinylpyrrolidone having a weight average molecular weight of 10,000, the trade name “polyvinylpyrrolidone (K15)” manufactured by Tokyo Chemical Industry Co., Ltd. was used. As the polyvinylpyrrolidone having a weight average molecular weight of 40,000, the trade name “polyvinylpyrrolidone (K30)” manufactured by Tokyo Chemical Industry Co., Ltd. was used. As the polyvinylpyrrolidone having a weight average molecular weight of 360000, the trade name “polyvinylpyrrolidone (K90)” manufactured by Tokyo Chemical Industry Co., Ltd. was used. As the polyoxyethylene polyoxypropylene glyceryl ether having a weight average molecular weight of 2500, the trade name "Brownon GEP-2500" manufactured by Aoki Yushi Kogyo Co., Ltd. was used.

(Example 9)
While stirring at a rotation speed of 300 rpm using a two-blade stirring blade, 200 g of the cerium hydroxide slurry and 1400 g of deionized water were mixed to obtain a mixed solution. Subsequently, 400 g of the cerium oxide slurry is mixed with the mixed solution while stirring the mixed solution, and then ultrasonic waves are irradiated using an ultrasonic cleaner (device name: US-105) manufactured by SND Co., Ltd. It was stirred while stirring. Subsequently, a polymer compound (polyethylene glycol having a weight average molecular weight of 20000, manufactured by Wako Pure Chemical Industries, Ltd., trade name "polyethylene glycol 20000"), 2,2-bis (hydroxymethyl) propionic acid, and a pH adjuster ( 3,5-Dimethylpyrazole) and deionized water were mixed. As a result, 0.1% by mass of abrasive grains, 0.4% by mass of hydroxy acids, 0.1% by mass of polymer compound and 0.1% by mass of pH adjuster are contained based on the total mass of the polishing liquid for CMP. A polishing solution for CMP was obtained. The polishing liquid for CMP contains composite particles containing cerium oxide particles and cerium hydroxide particles in contact with the cerium oxide particles as abrasive grains, and the cerium oxide particles and cerium hydroxide. The mass ratio to the particles was 10: 1 (cerium oxide: cerium hydroxide). In addition to the above-mentioned composite particles, the polishing liquid for CMP contained cerium hydroxide particles (free particles) that were not in contact with the cerium oxide particles.

<Measurement of zeta potential of abrasive grains>
A suitable amount of a polishing liquid for CMP was put into DelsaNano C, a trade name manufactured by Beckman Coulter Co., Ltd., and the measurement was carried out twice at 25 ° C. The average value of the displayed zeta potentials was obtained as the zeta potentials. The zeta potential of the abrasive grains was +50 mV in both Examples and Comparative Examples.

<Measurement of average grain size of abrasive grains>
A suitable amount of each of the above-mentioned polishing liquids for CMP was put into Microtrac MT3300EXII, a trade name manufactured by Microtrac Bell Co., Ltd., and the average particle size of the abrasive grains was measured. The displayed average particle size value was obtained as the average particle size (average secondary particle size) of the abrasive grains. The average particle size of Examples 1 to 8 and 10 to 13 and Comparative Examples 1 to 2 was 145 nm. The average particle size of Example 9 was 155 nm.

<pH measurement of polishing liquid for CMP>
The pH of the polishing liquid for CMP was measured under the following conditions. The results are shown in Tables 1 and 2.
Measurement temperature: 25 ° C
Measuring device: DKK-TOA CORPORATION, model number PHL-40
Measurement method: Two-point calibration was performed using a standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C); neutral phosphate pH buffer, pH: 6.86 (25 ° C)). After that, the electrode was put into a polishing solution for CMP, and the pH after lapsed for 2 minutes or more and stabilized was measured by the measuring device.

<CMP evaluation>
The substrate to be polished was polished under the following polishing conditions using the polishing liquid for CMP.
Polishing device: Reflection LK (manufactured by Applied Materials)
Flow rate of polishing liquid for CMP: 250 mL / min
Substrate to be polished: Substrate to be polished having a silicon oxide film (TEOS film) on the silicon substrate Polishing pad: manufactured by Roam & Haas Japan Co., Ltd., model number IC1010
Polishing pressure: 3psi
Rotation speed: Substrate to be polished / Polishing surface plate = 93/87 rpm
Polishing time: 1 min (60 seconds)
Wafer cleaning: After the CMP treatment, the wafer was washed with water while applying ultrasonic waves. Further, it was washed with a brush for 45 seconds while flowing 0.25% by mass of aqueous ammonia, and then dried with a spin dryer.

(Evaluation of cleanability)
The number of defects of 0.15 μm or more (the number of remaining abrasive grains) remaining on the silicon oxide film polished and washed under the above conditions is measured using a defect measuring device (manufactured by Applied Materials, trade name: Compulus). did. Further, the ratio of the number of defects in the other examples (defect reduction rate) to the number of defects in Comparative Example 1 was calculated from the following formula. The results are shown in Tables 1 and 2.
Defect reduction rate [%] = [(Number of defects in Comparative Example 1)-(Number of defects in Example 1)] / (Number of defects in Comparative Example 1) x 100

(Evaluation of polishing speed)
_{The polishing rate (SiO 2} RR) of the silicon oxide film polished and washed under the above conditions was calculated from the following formula. The difference in film thickness of the silicon oxide film before and after polishing was determined using a light interference type film thickness measuring device (manufactured by Filmometry, trade name: F80). The results are shown in Tables 1 and 2.
Polishing speed = (difference in film thickness of silicon oxide film before and after polishing [nm]) / (polishing time: 1 [min])

Claims (18)

It contains abrasive grains, a hydroxy acid, a polymer compound having at least one selected from the group consisting of hydroxyl groups and amide groups, and a liquid medium.
The zeta potential of the abrasive grains is positive,
A polishing liquid having a weight average molecular weight of 3000 or more of the polymer compound. The polishing liquid according to claim 1, wherein the abrasive grains contain cerium oxide. The abrasive grains include a first particle and a second particle in contact with the first particle.
The particle size of the second particle is smaller than the particle size of the first particle,
The first particle contains cerium oxide and
The polishing liquid according to claim 1 or 2, wherein the second particles contain a cerium compound. When the abrasive grains centrifuge the aqueous dispersion having the abrasive grains content adjusted to 1.0% by mass at a centrifugal acceleration of 5.8 × 10 ⁴ G for 5 minutes, the absorbance with respect to light having a wavelength of 380 nm is 0. The polishing liquid according to any one of claims 1 to 3, which provides a liquid phase exceeding the above. The polishing solution according to any one of claims 1 to 4, wherein the hydroxy acid has two hydroxyl groups. The polishing liquid according to any one of claims 1 to 5, wherein the content of the hydroxy acid is 0.01 to 1.0% by mass. The polishing solution according to any one of claims 1 to 6, wherein the polymer compound contains a compound having a polyoxyalkylene structure. The polishing solution according to any one of claims 1 to 7, wherein the polymer compound contains two or more compounds having the same structural unit having a hydroxyl group. The polishing solution according to any one of claims 1 to 8, wherein the polymer compound contains a compound having a secondary amide group. The polishing solution according to any one of claims 1 to 9, wherein the polymer compound contains a compound having a tertiary amide group. The polishing solution according to any one of claims 1 to 10, wherein the polymer compound contains a compound having a side chain containing an amide group. The polishing solution according to any one of claims 1 to 11, wherein the polymer compound contains a compound having a main chain containing hydroxyl groups at both ends. The polishing liquid according to any one of claims 1 to 12, wherein the content of the polymer compound is 0.01 to 5.0% by mass. The polishing solution according to any one of claims 1 to 13, wherein the pH is less than 8.0. The constituent component of the polishing liquid according to any one of claims 1 to 14 is stored separately as a first liquid and a second liquid, and the first liquid is the abrasive grains and the liquid medium. , And the second liquid contains the hydroxy acid, the polymer compound, and a liquid medium. The polishing liquid according to any one of claims 1 to 14 or the polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set according to claim 15 is used. A polishing method including a polishing process for polishing the surface to be polished. The polishing method according to claim 16, wherein the surface to be polished contains silicon oxide. The polishing method according to claim 16 or 17, further comprising a step of bringing an alkaline solution into contact with the surface to be polished after the polishing step.