TW201412907A - Polishing solution, preservation solution and polishing method for cmp - Google Patents

Abstract

The present invention relates to a polishing solution for CMP, which comprises silica particles, a quaternary phosphonium salt having at least one aromatic ring bound to a phosphorous atom and water, wherein each of the silica particles has a silanol group density of 1.0 to 2.0 /nm2 and an aspect ratio of 1.3 or more, the zeta potential in the polishing solution for CMP is +10 mV or more, and the ratio of the content of the silica particles to the content of the quaternary phosphonium salt is 750 or more.

Description

CMP polishing liquid, storage liquid and grinding method

The present invention relates to a polishing liquid for a chemical mechanical polishing (CMP), a storage liquid, and a polishing method for polishing in a wiring forming step of a semiconductor element or the like, which is used to obtain The polishing liquid uses the polishing liquid.

In recent years, with the high integration and high performance of semiconductor integrated circuits (hereinafter referred to as "LSI"), new microfabrication technologies have been continuously developed. A chemical mechanical polishing (hereinafter referred to as "CMP") method is also one of them, and this technique is frequently used for planarization of an insulating material (for example, an interlayer insulating film) in an LSI manufacturing step, particularly a multilayer wiring forming step. , formation of a metal plug, formation of buried wiring, and the like.

In the formation of buried wiring, a damascene process is employed. The damascene process is a process of: (1) forming a groove on the insulating material having a base material of an insulating material; (2) depositing a copper-based metal (referred to as copper and a copper alloy, the same as the following) as a metal for the wiring portion; (3) The metal for the wiring portion other than the groove portion is removed by CMP to form a buried wiring.

On the other hand, a barrier material layer is formed on the lower layer of the wiring portion metal to prevent the wiring portion metal from diffusing into the insulating material, and the wiring portion is lifted. Adhesion between metal and insulating material. Since the barrier material is a conductor, it is necessary to remove the barrier material other than the wiring portion by CMP.

However, since the hardness of the barrier material is usually higher than that of the metal for the wiring portion, even if the polishing liquid for removing the metal for the wiring portion is used for polishing, a sufficient polishing rate cannot be obtained. Therefore, a grinding method is studied which comprises two stages: a first grinding step of grinding the metal for the wiring portion; and a second grinding step of grinding the barrier material.

Fig. 1 is a schematic cross-sectional view showing the formation of wiring based on a normal damascene process. Fig. 1(a) is a view showing a substrate 100 before polishing, and a substrate (not shown) such as a germanium wafer, comprising: an insulating material 1 having a groove formed on its surface; and a barrier material 2 to follow the insulating material 1. The surface irregularities are formed; and the wiring portion metal 3 is deposited by filling the recesses.

First, as shown in Fig. 1(b), the polishing liquid for polishing the wiring portion metal 3 is polished to remove the wiring portion metal 3 until the barrier material 2 is exposed, thereby obtaining the substrate 200 (first polishing step). Then, the barrier material is polished with a barrier material, and the barrier material 2 is removed until the convex portion of the insulating material 1 is exposed, thereby obtaining the substrate 300 (second polishing step). In the second grinding step, most of the over-polishing of the partially insulating material 1 is performed. In the first (c) diagram, the broken line 4 indicates the state of the substrate 200 before the barrier material in the second polishing step is polished. By such excessive polishing, the flatness of the surface to be polished after polishing can be improved.

As such a polishing liquid for a barrier material, there has been proposed a CMP abrasive comprising an oxidizing agent, a protective film forming agent for a metal surface, an acid, and water, having a pH of 3 or less and an oxidizing agent concentration of 0.01 to 3% by mass. (reference For example, Patent Document 1. )

However, in recent years, as the wiring interval has become finer, a problem of signal delay has begun to occur. The integrated circuit is surrounded by several layers of metal wiring to transmit signals, but with the miniaturization, the distance between the wirings becomes close. Therefore, the capacitance (inter-wiring capacity) between the adjacent wirings is increased, and a phenomenon (signal delay) in which the signal transmitted to the wiring becomes sluggish is generated. As a result, the speed of the circuit does not increase, but the problem of increased power consumption is becoming more and more significant.

Therefore, in order to overcome this problem, it is studied to reduce the capacity between wirings. As one of the methods, the insulating material is converted from a low dielectric constant material (hereinafter referred to as "low-k material") from a material mainly composed of cerium oxide which has been used in the past. These low-k materials use an organic compound as a raw material to lower the dielectric constant by forming voids in the film.

Further, since a low-k material is used, development of a material having a relative dielectric constant as low as air (~1) has begun. These are referred to as ultra low dielectric constants (Ultra low-k, ULK) and the like, and are studied in the direction of using a porous (porous) material containing air. However, the porous material is softer than the material having a dense structure because it is a hollow structure such as a honeycomb structure. Therefore, compared with the cerium oxide film, it has the following weaknesses: low mechanical strength, high hygroscopicity, and low plasma resistance and chemical resistance. Therefore, in the second polishing step described above, there are new problems such as low-k material damage, excessive polishing, and film peeling.

Therefore, in order to overcome the above problems, a structure in which a low-k material is covered with cerium oxide is proposed. Fig. 2 is a view showing an example of a manufacturing process of an element having such a structure. In order to obtain the structure of the second (a) figure, first, on the substrate 5 in order After forming the low-k material 6 and the coating layer 7 formed of cerium oxide to form a laminated structure, a ridge portion and a groove portion are formed. The barrier material 2 is formed thereon so as to follow the surface of the raised portion and the surface of the groove portion, and the deposited wiring portion metal 3 is formed as a whole by filling the groove portion.

If the insulating material partially contains the cap layer of cerium oxide, it is affected by the dielectric constant of the cerium oxide. Therefore, the effective relative dielectric constant of the insulating material as a whole is not so low. That is, at this time, the low dielectric constant characteristics of the low-k material cannot be fully utilized. Therefore, it is desirable that the ruthenium dioxide film as the aforementioned cover layer is removed when the foregoing barrier material is ground, so that the portion of the insulating material is finally composed only of the low-k material.

In order to obtain an element having such a structure, first, the state of the substrate 110 shown in Fig. 2(a) is polished to the state of the substrate 210 shown in Fig. 2(b). Specifically, the wiring portion metal 3 is polished by the polishing liquid for polishing the wiring portion metal 3 until the barrier material 2 is exposed (first polishing step). Then, the barrier material 2 is polished with a polishing liquid for the barrier material, and polished to the state of the substrate 310 shown in FIG. 2(c), that is, at least the cap layer 7 of the ceria is removed, and the low-k material 6 is removed. Exposed (second grinding step). At this time, depending on the case, excessive grinding of the low-k material may be additionally performed.

Therefore, in the second polishing step, not only the material for the barrier material and the wiring portion but also the coating layer, that is, the cerium oxide and a part of the low-k material, are required to be polished. Further, since the semiconductor element is constructed in accordance with the design, in order to realize the multilayer wiring, it is necessary to control as much as possible the amount of the low-k material which is removed after the cover layer is removed (the amount to be removed). For this reason, the polishing liquid needs to exhibit a high polishing rate for an insulating material such as cerium oxide, and a low-k material or the like. The insulating material exhibits a low grinding speed. There is proposed a polishing liquid for CMP containing abrasive grains, a metal oxide dissolving agent, an oxidizing agent, water, and a quaternary phosphonium salt in order to cope with such a requirement in a process, and the abrasive grains are used in a polishing liquid for CMP. It has a zeta potential (see, for example, Patent Document 2).

[Advanced technical literature] (Patent Literature)

Patent Document 1: International Publication No. WO01/13417 Manual

Patent Document 2: JP-A-2011-023488

However, many conventional polishing liquids for barriers are suitable for polishing barrier materials and cerium oxide, but have problems in that the polishing rate of the low-k material is too fast, or scratches, film peeling, and the like are caused during the polishing process. As a result, the above process has not been fully put into practical use because there is no most suitable polishing liquid.

Further, in addition to the requirement that the CMP polishing liquid have a suitable polishing rate corresponding to such a polished article, it is also required to ensure the flatness of the surface to be polished after polishing. However, according to the findings of the inventors, it has been found that when a substrate having a narrow wiring interval is polished by a conventional polishing liquid, flatness is deteriorated from the viewpoints of cracks, corrosion, and the like, compared with a substrate having a wide interval between polishing wires. tendency.

The present invention has been made in view of various problems of the conventional polishing liquid, and an object of the invention is to provide a polishing liquid for CMP and a storage liquid for obtaining the polishing liquid, and the polishing liquid for the CMP is for a metal for a wiring portion. Resistance The spacer material and the cerium oxide are excellent in polishing rate, and on the other hand, the polishing rate of the low-k material can be suppressed, and even when the substrate having a narrow wiring interval is polished, the flatness of the surface to be polished can be sufficiently ensured. Further, an object of the present invention is to provide a polishing method using the polishing liquid for CMP.

The present inventors conducted various studies in order to solve the aforementioned problems, and as a result, found that by combining a quaternary phosphonium salt having at least one aromatic ring bonded to a phosphorus atom with cerium oxide particles having specific characteristics as abrasive grains And use, to obtain the desired grinding characteristics. In particular, it has been found that, in the case where the cerium oxide particles and the above-described quaternary phosphonium salt are used in combination, the cerium oxide particles have (A) stanol group density, (B) aspect ratio, and (C) boundary potential, and The ratio of the content of (D) cerium oxide particles to the content of the above-mentioned quaternary phosphonium salt is an important factor for any of the above problems.

That is, the present invention provides a polishing liquid for CMP comprising cerium oxide particles, a quaternary phosphonium salt having at least one aromatic ring bonded to a phosphorus atom, and water, and the cerium group density of the cerium oxide particles is 1.0 to 2.0 pieces/nm ² , the aspect ratio is 1.3 or more, and the boundary potential in the polishing liquid for CMP is +10 mV or more, and the ratio of the content of the cerium oxide particles to the content of the fourth-order cerium salt is 750 or more.

By using such a polishing liquid, a polishing liquid for CMP which polishes the metal for a wiring portion, a barrier material, and cerium oxide at a high speed can suppress the polishing rate of the low-k material. Moreover, the flatness of the surface to be polished after polishing can be sufficiently ensured.

Furthermore, the polishing liquid for CMP is also considered to be kept on a regular basis. In the case of post-use, therefore, in addition to the above various problems, the long-term dispersion stability of the slurry is also sought. In the conventional polishing liquid, the dispersion stability of the abrasive grains tends to be gradually deteriorated, so that the sedimentation of the abrasive grains is likely to occur, and the polishing is not suitable for polishing after a certain period of storage. However, in the polishing liquid of the present invention, the cerium oxide particles are It has good dispersion stability and can be suitable for grinding after a certain period of storage.

The above-mentioned quaternary phosphonium salt is preferably a compound represented by the following formula (1).

In the formula (1), R represents an alkyl group or an aryl group which may have a substituent, and X ^- represents an anion.

Further, the inventors have estimated the reason why the desired polishing property can be obtained by adopting such a configuration in the present invention.

First, a terminal (surface) of the cerium oxide particles contained in the polishing liquid is usually present with a stanol group (Si-OH group). The hydrogen atoms in the stanol group are substantially not dissociated in the acidic region, and therefore, the boundary of the usual cerium oxide particles is located in the acidic region to exhibit a number of positive numbers, or values close to zero. However, by setting the aforementioned stanol group density to a small range of 1.0 to 2.0 pieces/nm ² , it is possible to have a large positive value (+10 mV or more) in the acidic region. Here, since the low-k material is positively charged in the polishing liquid, it is presumed that the polishing rate of the low-k material can be suppressed by electrostatic repulsion with the cerium oxide particles having such an boundary potential. Moreover, the polishing liquid for CMP is excellent in the dispersibility of the cerium oxide particles because the boundary potential of the cerium oxide particles in the polishing liquid for CMP is +10 mV or more.

Further, the quaternary phosphonium salt represented by the above formula (1) has, for example, a hydrophobic substituent bonded to a phosphorus atom, that is, an alkyl group or an aryl group R. Since the low-k material is hydrophobic, the quaternary phosphonium salt having such a hydrophobic substituent has an affinity with the low-k material. That is, the surface of the low-k material is positively charged by the proximity of the alkyl or aryl group R of the quaternary phosphonium salt to the surface of the low-k material. As a result, it is generally believed that the surface of the low-k material is further positively charged, and electrostatic repulsion is generated with the cerium oxide particles, thereby suppressing the polishing rate of the low-k material.

On the other hand, in the polishing liquid, the cerium oxide particles are positively charged in association with the quaternary phosphonium salt, and the metal for the wiring portion (for example, a copper-based metal). The copper-based metal means copper and a copper alloy. The copper alloy refers to an alloy containing 50% by mass or more of copper. The surface is also positively charged. Therefore, it is considered that the cerium oxide particles adsorbed by the quaternary phosphonium salt are electrostatically repelled by the metal for the wiring portion. When the content of the quaternary phosphonium salt in the polishing liquid is more than a specific amount and is contained, the quaternary phosphonium salt is excessively adsorbed to the ceria particles, so that the electrostatic repulsion of the ceria particles and the metal for the wiring portion is enhanced, and the wiring is increased. The grinding speed of the metal is suppressed. In other words, the smaller the content ratio of the cerium oxide particles to the quaternary phosphonium salt, the more the polishing rate of the metal for the wiring portion is suppressed. Therefore, suitable polishing cannot be performed. In the present invention, the ratio of the content of the cerium oxide particles to the content of the quaternary phosphonium salt (the content of the cerium oxide particles/the content of the quaternary phosphonium salt) is 750 or more, and the larger the metal for the wiring portion, the more the metal can be obtained. More good grinding speed.

The above-mentioned quaternary phosphonium salt is preferably selected from the group consisting of butyl triphenyl phosphonium salt, pentyl triphenyl phosphonium salt (amyl triphenyl phosphonium salt), hexyl triphenyl phosphonium salt, At least one of the group consisting of n-heptyltriphenylphosphonium salt, tetraphenylphosphonium salt, and benzyltriphenylphosphonium salt. According to such a polishing liquid, the hydrophobicity of the quaternary phosphonium salt adsorbed to the ceria particles is not so high, and there is a tendency that the aggregation and sedimentation of the ceria particles are more suppressed.

The content of the quaternary phosphonium salt is preferably 0.0005 parts by mass or more and less than 0.005 parts by mass based on 100 parts by mass of the polishing liquid for CMP. By making this content into this range, it is easy to suppress excessive adsorption of the cerium oxide particles by the quaternary phosphonium salt, and therefore, aggregation and sedimentation of the cerium oxide particles can be further suppressed.

The cerium oxide particles are preferably colloidal cerium oxide particles. According to such a polishing liquid, the density of the stanol group, the aspect ratio, and the value of the boundary potential can be easily changed. Further, in the case of colloidal cerium oxide particles, various grades can be easily obtained.

The content of the cerium oxide particles is preferably 1.0 to 15.0 parts by mass based on 100 parts by mass of the polishing liquid for CMP. Thereby, a polishing liquid for CMP which can obtain a polishing rate of a more excellent insulating material is provided. Further, it is easier to suppress aggregation and sedimentation of the cerium oxide particles, and as a result, a polishing liquid for CMP having more excellent dispersion stability and storage stability can be provided.

In addition, the pH of the polishing liquid for CMP of the present invention is preferably 6.0 or less from the viewpoint of the fact that the boundary potential of the cerium oxide particles is controlled to be positive (+), and the wiring portion is in addition to the above viewpoint. The polishing speed of the metal and the barrier material is more preferably 5.0 or less, and more preferably 4.5 or less.

The polishing liquid for CMP of the present invention preferably contains more metal dissolved Agent. Thereby, a more excellent polishing rate for a metal such as a wiring portion or a barrier material can be obtained.

The polishing liquid for CMP of the present invention preferably further contains a metal oxidizing agent. Thereby, a polishing liquid for CMP is provided which exhibits a more excellent polishing rate with respect to the metal for the wiring portion and the barrier material.

The polishing liquid for CMP of the present invention preferably further contains a metal corrosion inhibitor. Thereby, etching of the metal for wiring portions is suppressed, and further, it is easy to prevent cracks from occurring on the surface after polishing.

The metal corrosion inhibitor is preferably a compound having a triazole skeleton (triazole compound). By using a metal corrosion inhibitor having a triazole skeleton in the polishing liquid containing the cerium oxide particles and the quaternary phosphonium salt, the etching of the metal for the wiring portion can be more effectively suppressed, and the surface after polishing can be easily prevented. Cracks appear on it.

The polishing liquid for CMP of the present invention preferably further contains a water-soluble polymer. Thereby, the flattening performance of the polishing liquid on the surface to be polished is further enhanced, and the occurrence of corrosion is more easily suppressed in the dense portion of the fine wiring portion.

The polishing liquid for CMP of the present invention preferably further contains an organic solvent. Thereby, the wettability of the surface to be polished with respect to the polishing liquid for CMP is improved, and the polishing rate of the ruthenium dioxide or the low-k material can be adjusted more satisfactorily. Further, when the polishing liquid for CMP contains a component which is hard to be dissolved in water, it can be dissolved in water.

The present invention further provides a storage liquid for obtaining the above-mentioned polishing liquid for CMP, and obtaining the aforementioned polishing liquid for CMP by dilution with a liquid medium. According to the storage liquid, storage and transportation of the polishing liquid for CMP can be reduced. And related costs such as custody.

Moreover, the present invention provides a polishing method which is a method of polishing a substrate, the substrate comprising: a low-k material; and cerium oxide covering at least a portion of the low-k material; and comprising abrasive cerium oxide In the polishing step in which the low-k material is exposed, the polishing liquid for CMP of the present invention is supplied while being polished in the polishing step.

According to such a polishing method, since the polishing liquid can polish the cerium oxide at a high speed and can suppress the polishing rate of the low-k material to perform polishing, the cerium oxide present on the substrate can be preferentially removed with respect to the low-k material. . Moreover, the flatness of the surface to be polished after polishing can be sufficiently ensured.

Moreover, the present invention provides a polishing method, which is a method of polishing a substrate, the substrate comprising: a low-k material having a concave portion and a convex portion on one side; and a cerium oxide covering the convex portion of the low-k material; a barrier material covering the low-k material and the cerium oxide; and a wiring portion metal covering the barrier material and filling the recess; and the polishing method includes: a first grinding step of grinding the wiring portion with a metal to Exposing the barrier material on the convex portion; and a second polishing step of polishing the barrier material on the convex portion and the cerium oxide to expose the convex portion; wherein, in the second step, supplying the CMP for the present invention The polishing liquid is polished.

According to such a polishing method, the metal for the wiring portion, the barrier material, and the cerium oxide can be polished at a high speed, and the polishing rate of the low-k material can be suppressed to perform polishing. Moreover, the flatness of the surface to be polished after polishing can be sufficiently ensured.

The metal for the wiring portion is preferably a metal containing copper as a main component. In addition, the main component is a copper containing 50 mass % or more. That is, for the wiring part The metal is preferably copper or a copper alloy containing 50% by mass or more of copper.

Further, the barrier material is a barrier conductive material for preventing diffusion of the wiring portion metal to the insulating material, and preferably comprises a material selected from the group consisting of tantalum, tantalum nitride, niobium alloy, titanium, titanium nitride, titanium alloy, tantalum, niobium alloy, cobalt, At least one of the group consisting of a cobalt alloy, a manganese, and a manganese alloy.

According to the present invention, it is possible to provide a polishing liquid for CMP and a storage liquid for obtaining the polishing liquid. The polishing liquid for CMP is excellent in polishing rate for a metal for a wiring portion, a barrier material, and cerium oxide. The polishing rate of the low-k material is suppressed, and the flatness of the surface to be polished can be sufficiently ensured. Moreover, according to the present invention, a polishing method using the polishing liquid for CMP can be provided.

More specifically, according to the present invention, it is possible to provide a polishing liquid for CMP which is excellent in dispersion stability of abrasive grains, and in a second polishing step of polishing a barrier material, a low-k material under practical grinding conditions can be used. The polishing rate is suppressed to about 100 Å/min or less, and the polishing rate of the barrier material and the ceria material can be made 7 times or more with respect to the polishing rate of the low-k material.

1‧‧‧Insulation material

2‧‧‧Blocking materials

3‧‧‧Metal for wiring department

4‧‧‧ dotted line

5‧‧‧矽 substrate

6‧‧‧low-k material (insulation material)

7‧‧‧ Coverage

10‧‧‧2O2 particles

11‧‧‧External rectangle

100, 110, 200, 210, 300, 310‧‧‧ substrates

Fig. 1 is a schematic cross-sectional view showing the formation of wiring based on a normal damascene process.

Fig. 2 is a schematic cross-sectional view showing the formation of a wiring using an insulating material, that is, a low-k material and a cover layer.

Figure 3 is a graph showing the calculation of the biaxial average primary particle size and aspect ratio of particles. Schematic diagram of the method.

Hereinafter, a suitable embodiment of the polishing liquid for CMP of the present invention will be sequentially described. The polishing liquid for CMP of the present embodiment contains cerium oxide particles, a quaternary phosphonium salt having at least one aromatic ring bonded to a phosphorus atom, and water, and the cerium oxide group has a stanol group density of 1.0 to 2.0. /nm ² , the aspect ratio is 1.3 or more, and the boundary potential in the polishing liquid for CMP is +10 mV or more, and the ratio of the content of the cerium oxide particles to the content of the quaternary phosphonium salt is 750 or more.

In the polishing liquid for CMP of the embodiment, the metal for the wiring portion, the barrier material, and the cerium oxide can be polished at a high speed, and the polishing rate of the low-k material can be suppressed. Further, the dispersion stability of the cerium oxide particles is also good.

(I. Grade IV salt)

The quaternary phosphonium salt is not particularly limited as long as it is a compound having at least one aromatic ring bonded to a phosphorus atom, but preferably has two or more aromatic rings bonded to a phosphorus atom. Preferably, it has three or more aromatic rings bonded to a phosphorus atom. Among them, a compound represented by the following formula (1) is suitably used.

In the formula (1), R represents an alkyl group or an aryl group which may have a substituent, and X ^- represents an anion.

In the formula (1), the alkyl group R which may have a substituent is preferably at least one selected from the group consisting of a linear alkyl group and a branched alkyl group.

Further, the alkyl group in the formula (1) may be linear or branched as described above, and the number of carbon atoms of the alkyl group is preferably one or more and 14 or less, more preferably four or more and seven or less. When the number of carbon atoms of the alkyl group is 14 or less, the storage stability of the polishing liquid for CMP does not significantly decrease.

In the formula (1), the aryl group R which may have a substituent is not particularly limited, and examples thereof include a phenyl group, a benzyl group, a tolyl group, a xylyl group, and a naphthyl group, but the polishing liquid is further improved. From the viewpoint of solubility and dispersion stability of the cerium oxide particles, a phenyl group or a benzyl group is preferred.

Further, the anion X ^- in the formula (1) is not particularly limited, and examples thereof include a halogen ion (for example, F ^- , Cl ^- , Br ^- , and I ^- ), a hydroxide ion, a nitrate ion, and a nitrite ion. Chloride ion, chlorite ion, chlorate ion, perchlorate ion, acetate ion, hydrogen carbonate ion, phosphate ion, sulfate ion, hydrogen sulfate ion, sulfite ion, thiosulfate ion, and carbonate ion. Among them, a halogen ion is preferred.

In the polishing liquid for CMP of the present embodiment, by including such a specific quaternary phosphonium salt, the polishing rate of the low-k material can be more sufficiently suppressed without suppressing the polishing rate of the metal for the wiring portion. Further, the flattening performance of the polishing liquid on the surface to be polished is further enhanced, and the occurrence of corrosion is more easily suppressed in a portion where the fine wiring portion is dense.

More specifically, the quaternary phosphonium salt contained in the polishing liquid for CMP of the present embodiment is preferably selected from methyl triphenyl phosphonium salt and ethyl triphenyl sulfonium salt. Salt, propyltriphenylphosphonium salt, isopropyltriphenylphosphonium salt, butyltriphenylphosphonium salt, pentyl triphenylsulfonium salt (amyl triphenylsulfonium salt) , hexyltriphenylphosphonium salt, n-heptyltriphenylphosphonium salt, triphenyl(tetradecyl)phosphonium salt, tetraphenylphosphonium salt, benzyltriphenylphosphonium salt, (2-hydroxybenzyl) three Phenyl sulfonium salt, (2-chlorobenzyl) triphenyl sulfonium salt, (4-chlorobenzyl) triphenyl sulfonium salt, (2,4-dichlorobenzyl) phenyl sulfonium salt, (4-nitrate Benzyl)triphenylphosphonium salt, 4-ethoxybenzyltriphenylphosphonium salt, (1-naphthylmethyl)triphenylphosphonium salt, (cyanomethyl)triphenylphosphonium salt, (methoxyl) Methyl)triphenylphosphonium salt, (formamidinemethyl)triphenylphosphonium salt, acetonyltriphenylphosphonium salt, benzamidine methyltriphenylphosphonium salt, methoxycarbonylmethyl (triphenyl) Onium salt, ethoxycarbonylmethyl (triphenyl) phosphonium salt, (3-carboxypropyl) triphenyl phosphonium salt, (4-carboxybutyl) triphenyl phosphonium salt, (N-methyl-N- An aniline consisting of triphenylsulfonium salt, 2-dimethylaminoethyltriphenylphosphonium salt, triphenylvinylphosphonium salt, allyltriphenylphosphonium salt, and triphenylpropargyl sulfonium salt At least one of the groups. These may be used alone or in combination of two or more.

More preferably, it is selected from the group consisting of butyl triphenyl phosphonium salt, pentyl triphenyl phosphonium salt (amyl triphenyl phosphonium salt), hexyl triphenyl phosphonium salt, and n-heptyl group. At least one of the group consisting of triphenylsulfonium salt, tetraphenylphosphonium salt, and benzyltriphenylphosphonium salt.

The content of the quaternary phosphonium salt is preferably 0.0005 parts by mass or more, more preferably 0.0007 parts by mass or more, and still more preferably 0.0009 parts by mass or more, based on 100 parts by mass of the polishing liquid for CMP. Further, the content of the quaternary phosphonium salt is preferably less than 0.005 parts by mass, more preferably 0.004 parts by mass or less, still more preferably 0.003 parts by mass or less, even more preferably 0.002 parts by mass, per 100 parts by mass of the polishing liquid for CMP. Hereinafter, it is preferably 0.0015 parts by mass or less.

(II. cerium oxide particles)

The cerium oxide particles are not particularly limited as long as the stanol group density, the aspect ratio, and the boundary potential in the CMP polishing liquid are desired values. Further, the polishing liquid for CMP may contain particles (for example, alumina particles) other than the cerium oxide particles as the abrasive grains.

(II-i. stanol base density)

The cerium oxide particles used in the polishing liquid for CMP of the embodiment have a stanol group density of 1.0 to 2.0 / nm ² .

In the polishing liquid for CMP of the present embodiment, by having cerium oxide particles having a stanol group density of the above range, the boundary potential can be +10 mV or more. Thereby, the attractive force and the repulsive force of the static electricity on the surface to be polished become more remarkable, and the flattening performance is further improved. Moreover, even in a dense portion of the fine wiring portion, it is easy to suppress the occurrence of corrosion.

In the present embodiment, the stanol group density (ρ [pieces/nm ² ]) can be measured and calculated by the following titration. First, 1.5 g of cerium oxide particles (A [g]) was weighed and dispersed in an appropriate amount (100 mL or less) of water. Then, the pH was adjusted to 3.0 to 3.5 with 0.1 mol/L hydrochloric acid. Thereafter, 30 g of sodium chloride was added, and ultrapure water was added to make the total amount 150 g. This was adjusted to pH 4.0 with a 0.1 mol/L sodium hydroxide solution as a sample for titration. To the titration sample, 0.1 mol/L sodium hydroxide solution was added dropwise until the pH became 9.0, and the amount of sodium hydroxide (B [mol]) required before the pH was changed from 4.0 to 9.0 was obtained, and the following Formula (2) is used to calculate the density of the stanol group of the cerium oxide particles.

ρ=B‧N _A /A‧S _BET ......(2)

In the formula (2), N _A [unit/mol] represents an Avogadro constant, and S _BET [m ² /g] represents a BET specific surface area of the cerium oxide particles.

When the colloidal cerium oxide particles described later are cerium oxide particles obtained by dispersing in a medium such as water, the amount of cerium oxide particles (A[g]) is 1.5 g, which may be the same. The density of the stanol groups was determined sequentially. Further, the cerium oxide particles contained in the polishing liquid for CMP are separated from the CMP polishing liquid and washed, and then the stanol group density can be measured in the same order.

The BET specific surface area S _BET of the above cerium oxide particles is determined by the BET specific surface area method. As a specific measurement method, for example, a sample obtained by sufficiently degassing cerium oxide particles at 250 ° C can be obtained by a one-point method or a multi-point method of adsorbing nitrogen gas by using a BET specific surface area measuring device. More specifically, first, the cerium oxide particles are dried by a vacuum freeze dryer, and the residue is finely ground by a mortar (magnetic, 100 mL) to be used as a sample for measurement, and Yuasa Ionics (Yuasa Ionics) is used. The BET specific surface area measuring device (product name Autosorb 6) manufactured by Co., Ltd. was measured for its BET specific surface area S _BET .

The details of the calculation method of the aforementioned stanol group density are disclosed, for example, in Analytical Chemistry, 1956, Vol. 28, No. 12, p. 1981-1983, and Japanese Journal of Applied Physics, 2003, Vol. 42, P.4992-4997.

(II-ii. Two-axis average primary particle size)

The cerium oxide particles used in the polishing liquid for CMP of the embodiment are excellent in dispersion stability in the polishing liquid for CMP, and the number of polishing damage generated by CMP is small, and the two-axis average is used. Primary grain The diameter is preferably from 20 to 80 nm, more preferably the lower limit is 25 nm or more, and more preferably the upper limit is 70 nm or less. Therefore, the polishing liquid for CMP of the embodiment achieves the dispersion stability of the cerium oxide particles and the suppression of the polishing damage at a higher standard, and more preferably, the secondary primary particle diameter is 25 to 70 nm, for the same reason, More preferably, it is 35 to 70 nm.

In the present embodiment, the biaxial average primary particle diameter (R [nm]) is a result obtained by observing arbitrary 20 particles by a scanning electron microscope (SEM), and is calculated as follows. That is, if colloidal cerium oxide particles dispersed in ordinary water and having a solid concentration (solid content) of 5 to 40% by weight are taken as an example, an appropriate amount of liquid of colloidal cerium oxide particles is taken to soak the wafer. After about 30 seconds in the container containing the liquid, it is transferred to a container filled with pure water, rinsed for about 30 seconds, and nitrogen blow-drying the wafer, wherein the wafer is to be carried The wafer of the pattern wiring was cut into a quadrangular shape having a side length of 2 cm. Thereafter, the sample was placed on a sample stage for SEM observation, an acceleration voltage of 10 kV was applied, and cerium oxide particles were observed at a magnification of 100,000 times, and an image was taken. Any 20 cerium oxide particles are selected from the obtained images.

For example, when the selected cerium oxide particles have a shape as shown in Fig. 3, a rectangular shape (external rectangle 11) is drawn, and the rectangular shape is externally connected to the cerium oxide particles 10, and the long axis is the longest. Further, when the long axis of the circumscribed rectangle 11 is X and the minor axis is Y, the value of (X+Y)/2 is calculated as the biaxial average primary particle diameter of one particle. This operation is performed on any of the 20 cerium oxide particles, and the average value of the obtained values is referred to as the biaxial average primary particle diameter in the present embodiment.

(II-iii. Aspect Ratio)

In the polishing liquid of the present embodiment, the particle size ratio of the cerium oxide particles used in the polishing liquid of the present embodiment is 1.3 or more, and for the same reason, the aspect ratio is preferably 1.4 or more, more preferably It is 1.5 or more, more preferably 1.6 or more, particularly preferably 1.7 or more, and most preferably 1.8 or more. In addition, the upper limit of the aspect ratio of the cerium oxide particles is preferably 3.0 or less, more preferably 2.5 or less, and still more preferably 2.0 or less, from the viewpoint of sufficiently ensuring the dispersion stability of the cerium oxide particles.

Further, in the present embodiment, the aspect ratio is calculated by observing the results of arbitrary 20 cerium oxide particles by a scanning electron microscope (SEM) and averaging them. For example, when the selected cerium oxide particles have a shape as shown in Fig. 3, a rectangular shape (external rectangle 11) is drawn, and the rectangular shape is externally connected to the cerium oxide particles 10, and the long axis is the longest. Further, when the long axis of the circumscribed rectangle 11 is X and the minor axis is Y, the value of X/Y is calculated as the aspect ratio of the cerium oxide particles. This operation is performed on any of the 20 cerium oxide particles, and the average value of the obtained values is referred to as the aspect ratio in the present embodiment.

(II-iv. Jieda potential)

The cerium oxide particles used in the polishing liquid for CMP of the present embodiment are excellent in dispersibility, and it is possible to obtain a polishing rate of cerium oxide. The boundary potential in the polishing liquid for CMP is +10 mV or more. The boundary potential is preferably +15 mV or more, more preferably +17 mV or more, and still more preferably +20 mV or more. The upper limit of the boundary potential is not particularly limited, and normal polishing can be sufficiently performed at about +80 mV or less. In addition, as a method of setting the boundary potential to +10 mV or more, a method of adjusting the pH of the polishing liquid for CMP, that is, a coupling agent or a water-soluble polymer to a polishing liquid for CMP, may be mentioned. As the aforementioned water As the soluble polymer, a water-soluble cationic polymer can be suitably used.

In the present embodiment, the boundary potential (ζ[mV]) is measured using an boundary potential measuring device. At this time, the CMP slurry is diluted with pure water so that the scattering intensity of the measurement sample is 1.0×10 ⁴ to 5.0×10 ⁴ cps (here, cps means counts per second, that is, counting per second, which is the count of particles. The unit is the same as the above, and is placed in the cell for potential measurement, and the measurement is performed. In order to make the scattering intensity within the above range, for example, the polishing liquid for CMP is diluted with cerium oxide particles in an amount of 1.7 to 1.8 parts by mass based on 100 parts by mass of the polishing liquid.

The various cerium oxide particles having different sterol alcohol group density, biaxial average primary particle diameter, aspect ratio, and boundary potential can be easily obtained from a number of cerium oxide particle manufacturers, and the values can also be based on the manufacturer's opinion. Take control.

Further, as the type of the cerium oxide particles, known cerium oxide particles such as fumed silica particles or colloidal cerium oxide particles can be used, and the stanol group density and the two-axis average are easily obtained. From the viewpoint of the primary particle diameter, the aspect ratio, and the boundary potential of the cerium oxide particles, colloidal cerium oxide particles are preferred. Further, in the polishing liquid for CMP of the present embodiment, two or more kinds of cerium oxide particles may be used in combination as long as the above characteristics are satisfied.

(II-v. content)

The content of the cerium oxide particles is preferably 1.0 to 15.0 parts by mass based on 100 parts by mass of the polishing liquid for CMP. When the content of the cerium oxide particles having the above characteristics is 1.0 part by mass or more, a more preferable polishing rate for the insulating material may be obtained, and in the same viewpoint, it is more preferably 1.5 parts by mass or more, and still more preferably 2.0. It is especially preferably 2.5 parts by mass or more in parts by mass or more. In addition, when the same content is 15.0 parts by mass or less, there is a tendency that aggregation and sedimentation of particles are more easily suppressed, and as a result, good dispersion stability and storage stability can be obtained. From the same viewpoint, it is more preferably 12.5 parts by mass or less, still more preferably 10.0 parts by mass or less. In addition, the content here means the preparation amount in the state which is prepared in the state which can be used for the CMP grinding|polishing process, and is not the preparation amount at the time of the liquid-separation-preservation or the concentrating storage.

However, in the present embodiment, it is important that the ratio of the content of the cerium oxide particles to the content of the quaternary phosphonium salt (the content of the cerium oxide particles/the content of the quaternary phosphonium salt) is 750 or more. By setting the content ratio of the two to 750 or more, a more excellent polishing rate for the metal for the wiring portion can be obtained. From this point of view, the content is preferably 750 or more, more preferably 1,000 or more. On the other hand, the upper limit of the content ratio is not particularly limited, but is preferably 30,000 or less.

(III.pH)

The polishing liquid for CMP of the present embodiment has a characteristic that a good polishing rate for the barrier material and the ceria can be obtained, and the polishing rate of the low-k material can be suppressed. However, as described above, in the polishing of the barrier material, it is preferably used as a polishing liquid for CMP in the case of excessive polishing, and it is preferable to further maintain the polishing rate of the metal for the wiring portion and the barrier material to a good value. In this regard, the pH (25 ° C) of the polishing liquid for CMP of the present embodiment is preferably 6.0 or less.

When an organic acid compound or an inorganic acid compound is used as a metal dissolving agent to be described later, it is easy to suppress corrosion of the metal for the wiring portion, and it is easy to suppress the dishing caused by excessive polishing of the metal for the wiring portion. More preferably, it is 1.5 or more, still more preferably 1.8 or more, and particularly preferably 2.0 or more. Furthermore, if the pH is 2.0 or more, it is easier than when the acidity is too strong. operating. On the other hand, the pH is preferably 5.0 or less, more preferably 4.5 or less, and particularly preferably 4.0 or less, and particularly preferably 3.5, in view of obtaining a good polishing rate for the conductor for the wiring portion metal and the barrier material. Hereinafter, it is preferably 3.0 or less.

On the other hand, when an amino acid is contained as a metal-dissolving agent mentioned later, pH is a neutral-region. Here, the neutral region is defined as pH: 6.5 or more and 7.5 or less, and the acidic region is defined as pH: less than 6.5.

The pH of the polishing liquid can be measured by a pH meter (for example, manufactured by Yokogawa Electric Corporation, model pH 81). As a pH, after using a standard buffer (phthalic acid pH buffer: pH 4.01 (25 ° C), neutral phosphate pH buffer: pH 6.86 (25 ° C)), after two-point calibration, The electrode is placed in the slurry and passed for more than 2 minutes and stabilized.

(IV. Medium)

The medium for the CMP polishing liquid is not particularly limited, and may be a liquid in which the cerium oxide particles are dispersible, and is used in the present embodiment in terms of operability, safety, and reactivity with the surface to be polished when pH is adjusted. A medium that uses water as its main component. More specifically, such water is preferably deionized water, ion-exchanged water, ultrapure water or the like.

An organic solvent other than water may be added to the polishing liquid for CMP as needed. These organic solvents can be used as a dissolution aid which is hardly soluble in water, or can be used for the purpose of improving the wettability of the surface to be polished with respect to the polishing liquid for CMP. The organic solvent in the polishing liquid for CMP of the present embodiment is not particularly limited, and is preferably an organic solvent which can be mixed with water, and may be used alone or in combination. Use in combination of two or more.

The organic solvent used as a dissolution aid may, for example, be a polar solvent such as an alcohol. Moreover, for the purpose of improving the wettability of the surface to be polished, for example, ethylene glycols, ethylene glycol monomethyl ethers, glycol diethers, alcohols, carbonates, and the like are mentioned. Lactones, ethers, ketones, phenols, dimethylformamide, n-methylpyrrolidone, ethyl acetate, ethyl lactate, and cyclobutyl hydrazine. Among them, at least one selected from the group consisting of ethylene glycol monomethyl ethers, alcohols, and carbonates is preferred.

When the organic solvent is blended, the content of the organic solvent is preferably 0.1 to 95 parts by mass based on 100 parts by mass of the polishing liquid for CMP. The content is more preferably 0.2 parts by mass or more, and still more preferably 0.5 parts by mass or more, from the viewpoint of improving the wettability of the substrate with respect to the polishing liquid for CMP. In addition, the upper limit is more preferably 50 parts by mass or less, and still more preferably 10 parts by mass or less, from the viewpoint of preventing difficulty in the production process.

Further, the content of water may be the remainder of the content of the other constituent components, and is not particularly limited as long as it is contained. Further, water may be used as a diluent for diluting the concentrated CMP polishing liquid described later to a concentration suitable for use.

(V. Other ingredients)

In the present embodiment, the main purpose of obtaining a higher polishing rate for the metal for the wiring portion and the barrier material is to further contain a metal dissolving agent or a metal oxidizing agent (hereinafter also referred to simply as "oxidizing agent"). When the pH of the polishing liquid for CMP is low, there is a possibility of causing etching of the metal for the wiring portion. Therefore, a metal corrosion inhibitor may be contained for the purpose of suppressing the occurrence of the polishing liquid. Following, this is equal to The points are explained.

(V-i. Metal Dissolving Agent)

The polishing liquid for CMP of the present embodiment preferably contains a metal dissolving agent in order to obtain a more excellent polishing rate for a metal such as a wiring portion metal or a barrier material. Here, the metal dissolving agent is defined as a substance which at least contributes to dissolving the oxidized wiring portion with water in water, and contains a substance known as a chelating agent or an etchant.

The metal dissolving agent is used for the purpose of adjusting the pH and dissolving the metal for the wiring portion, and is not particularly limited as long as it has such a function. Specifically, for example, an organic acid (wherein the following amine group is removed) An organic acid compound such as an organic acid ester or a salt of an organic acid; an inorganic acid compound such as a salt of an inorganic acid or an inorganic acid; and an amino acid. The aforementioned salt is not particularly limited, and is preferably an ammonium salt. These metal dissolving agents may be used singly or in combination of two or more kinds, and the organic acid, the inorganic acid, and the amino acid may be used in combination.

The metal dissolving agent preferably contains an organic acid compound, and more preferably an organic acid, while maintaining a practical CMP rate while effectively suppressing the etching rate. Examples of the organic acid include formic acid, acetic acid, glyoxylic acid, pyruvic acid, lactic acid, mandelic acid, ethylene acetic acid, 3-hydroxybutyric acid, oxalic acid, maleic acid, malonic acid, and methylmalonic acid. Dimethylmalonic acid, phthalic acid, tartaric acid, fumaric acid, malic acid, succinic acid, glutaric acid, oxalic acid, citric acid, semi-melanic acid, trimellitic acid, trimesic acid, Benzoic acid, isocitric acid, aconitic acid, souric acid, succinic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, trimethylacetic acid, caproic acid, caprylic acid, adipic acid, glycol Diacid, suberic acid, azelaic acid, sebacic acid, acrylic acid, propiolic acid, methacrylic acid, crotonic acid, isocrotonic acid, benzoic acid, cinnamic acid, isophthalic acid, terephthalic acid, citric acid, Thiophencarboxylic acid, nicotinic acid, isonicotinic acid, glycolic acid, salicylic acid, cresylic acid, vanillic acid, syringic acid, catechol formic acid, resorcylic acid, Gentioic acid, protocatechuic acid, oleic acid, gallic acid, hydroxymalonic acid, leucine, methyl dihydroxy valeric acid, broad acid, ricinoleic acid, ricinated acid Acid), cerebronic acid, citramalic acid, quinic acid, shikimic acid, mandelic acid, benzilic acid, atrolactic acid, o-dihydrocinnamic acid (melilotic) Acid), root acid, coumaric acid, umbellic acid, caffeic acid, ferulic acid, isoferulic acid, and sinapic acid; and maleic anhydride, propionic anhydride, An acid anhydride of an organic acid such as succinic anhydride or decanoic anhydride. In the above, the metal dissolving agent preferably contains at least one selected from the group consisting of formic acid, malonic acid, malic acid, tartaric acid, citric acid, salicylic acid, and adipic acid. These may be used alone or in combination of two or more.

The metal dissolving agent preferably contains a mineral acid in order to easily obtain a high polishing rate for the metal for the wiring portion. Specific examples thereof include monovalent inorganic acids such as hydrochloric acid and nitric acid; sulfuric acid, chromic acid, carbonic acid, molybdic acid, hydrogen sulfide, sulfurous acid, thiosulfuric acid, selenic acid, citric acid, telluric acid, and tungstic acid; And a divalent acid such as a phosphonic acid; a trivalent acid such as phosphoric acid, phosphomolybdic acid, phosphotungstic acid or vanadic acid; and a tetravalent or higher acid such as hydrazine molybdate, tungstic acid, pyrophosphoric acid or tripolyphosphoric acid. . When a mineral acid is used, nitric acid is preferred. These may be used alone or in combination of two or more.

In order to easily adjust the pH and to easily obtain a high polishing rate for the metal for the wiring portion, the metal dissolving agent preferably contains an amino acid. The amino acid is not particularly limited, and may be dissolved in water even in a small amount. Specific examples thereof include glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, and methionine. Aspartic acid, glutamic acid, lysine, arginine, phenylalanine, tyrosine, histidine, tryptophan, lysine, and hydroxyproline. These may be used alone or in combination of two or more.

When the metal dissolving agent is blended, the content thereof is preferably 0.001 to 20 parts by mass based on 100 parts by mass of the polishing liquid for CMP. The content is more preferably 0.002 parts by mass or more, and still more preferably 0.005 parts by mass or more, from the viewpoint that a metal such as a metal for a wiring portion and a metal such as a barrier material can easily obtain a good polishing rate. In addition, the upper limit is more preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and particularly preferably 3 parts by mass or less, from the viewpoint of suppressing the etching and preventing the occurrence of cracks on the surface to be polished.

(V-ii. Metal corrosion inhibitor)

The polishing liquid for CMP of the present embodiment preferably contains a metal corrosion inhibitor which forms a protective film for the metal for the wiring portion, suppresses etching of the metal for the wiring portion, and prevents the surface after polishing. Produce cracking function. Here, the metal corrosion inhibitor is defined as a material which can form a protective film on the metal for the wiring portion when used alone. Further, by immersing a sample having a metal for a wiring portion in an aqueous solution of a metal corrosion inhibitor, and analyzing the composition of the surface of the sample, it is possible to determine whether or not a protective film is formed. Further, in the polishing using the polishing liquid for CMP of the present embodiment, the wiring portion is made of metal. It is not necessary to form a protective film composed of the aforementioned metal corrosion inhibitor.

Specific examples of such a metal corrosion inhibitor include a triazole compound having a triazole skeleton in a molecule, a pyrazole compound having a pyrazole skeleton in the molecule, and a pyrimidine compound having a pyrimidine skeleton in the molecule. An imidazole compound having an imidazole skeleton in the molecule, an anthracene compound having an anthracene skeleton in the molecule, a thiazole compound having a thiazole skeleton in the molecule, and a tetrazole compound having a tetrazole skeleton in the molecule. These may be used alone or in combination of two or more.

Among them, a triazole compound is preferred, and specific examples thereof include 1,2,3-triazole, 1,2,4-triazole, and 3-amino-1H-1,2,4-triazole. Triazole derivatives; benzotriazole; 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole , 4-carboxy(-1H-)benzotriazole, 4-carboxy(-1H-)benzotriazole methyl ester, 4-carboxy(-1H-)benzotriazolebutyl, 4-carboxyl (-1H -) benzotriazole octyl ester, 5-hexyl benzotriazole, [1,2,3-benzotriazolyl-1-methyl][1,2,4-triazolyl-1-methyl [2-ethylhexyl]amine, tolyltriazole, naphthotriazole, bis[(1-benzotriazolyl)methyl]phosphonic acid, and 3-amino group a benzotriazole derivative such as benzotriazole or the like.

In order to suppress the occurrence of cracks on the surface after polishing, it is preferable to prevent the content of the metal corrosion inhibitor from being 0.001 part by mass or more with respect to 100 parts by mass of the polishing liquid for CMP. Preferably, it is 0.01 parts by mass or more. In addition, the upper limit is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 3 parts by mass or less, in order to maintain the polishing rate of the metal for the wiring portion and the barrier material at a practical polishing rate. It is especially preferably 2 parts by mass or less.

(V-iii. Metal oxidizer)

The polishing liquid for CMP of the present embodiment preferably contains a metal oxidizing agent having the ability to oxidize the metal for the wiring portion. Specific examples of such a metal oxidizing agent include hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, and ozone water. Among them, hydrogen peroxide is preferred. These may be used alone or in combination of two or more. Since the hydrogen peroxide is usually obtained as a hydrogen peroxide aqueous solution (hydrogen peroxide), the hydrogen peroxide aqueous solution can be used as a diluent when the polishing liquid for CMP of the present embodiment is used after being concentrated and stored as described later.

When the substrate is a tantalum substrate including an element for an integrated circuit, contamination by an alkali metal, an alkaline earth metal, a halide or the like is undesirable, and therefore, an oxidizing agent which does not contain a nonvolatile component is preferable. However, the time change of ozone water composition is frequent, and therefore, hydrogen peroxide is most suitable. In addition, when the substrate of the polishing article is a glass substrate or the like which does not include a semiconductor element, it may be an oxidizing agent containing a nonvolatile component.

The content of the metal oxidizing agent is preferably 0.01 to 50 parts by mass based on 100 parts by mass of the polishing liquid for CMP. The content is more preferably 0.02 parts by mass or more, and still more preferably 0.05 parts by mass or more from the viewpoint of easily preventing oxidation of the metal and reducing the polishing rate. In addition, the upper limit is more preferably 30 parts by mass or less, and still more preferably 10 parts by mass or less, from the viewpoint of preventing cracking on the surface to be polished. Further, when hydrogen peroxide is used as the oxidizing agent, the hydrogen peroxide aqueous solution is prepared in such a manner that hydrogen peroxide eventually reaches the above range.

Moreover, when the pH of the polishing liquid for CMP is an acidic region, it is self-available. The content of the oxidizing agent is preferably in the range of 0.01 to 3 parts by mass based on 100 parts by mass of the polishing liquid for CMP, from the viewpoint of a more preferable polishing rate of the barrier material. When the pH of the polishing liquid for CMP is from 1 to 4, the content of the oxidizing agent is about 0.15 parts by mass, and the polishing rate for the barrier material tends to be extremely large. From the viewpoint of the polishing liquid for CMP, 100 parts by mass of the polishing liquid is used. The content of the oxidizing agent is more preferably 2.5 parts by mass or less, still more preferably 2 parts by mass or less, particularly preferably 1.5 parts by mass or less, and most preferably 1.0 part by mass or less.

(V-iv: water soluble polymer)

The polishing liquid for CMP of the present embodiment may contain a water-soluble polymer. By including a water-soluble polymer, the polishing liquid for CMP further enhances the flattening performance of the polishing liquid on the surface to be polished, and also suppresses the occurrence of corrosion in a portion where the fine wiring portion is dense.

The weight average molecular weight of the water-soluble polymer is preferably 500 or more, more preferably 1,500 or more, still more preferably 5,000 or more, from the viewpoint that it can exhibit a high polishing rate. Further, the upper limit is not particularly limited, and is preferably 5,000,000 or less from the viewpoint of solubility in the polishing liquid for CMP. The weight average molecular weight of the water-soluble polymer can be determined by gel permeation chromatography, for example, using a calibration curve of standard polystyrene under the following conditions.

(condition)

Sample (sample): 10 μL

Standard polystyrene: Standard polystyrene manufactured by Tosoh Corporation (molecular weight; 190000, 17900, 9100, 2980, 578, 474, 370, 266)

Detector: manufactured by Hitachi, Ltd., RI-monitor, trade name "L-3000"

Integrator: manufactured by Hitachi, Ltd., GPC integrator, trade name "D-2200"

Pump: manufactured by Hitachi, Ltd., trade name "L-6000"

Degassing device: manufactured by Showa Electric Co., Ltd. (SHOWA DENKO K.K.), trade name "shodex DEGAS"

Column: manufactured by Hitachi Chemical Co., Ltd., and connected to the column with the trade names "GL-R440", "GL-R430", and "GL-R420".

Dissolution: tetrahydrofuran (THF)

Measuring temperature: 23 ° C

Flow rate: 1.75mL / min

Measurement time: 45 minutes

The water-soluble polymer is not particularly limited, and is preferably an acrylic polymer (polymerized or copolymerized as a monomer component containing a C=C-COOH skeleton as a monomer component). Polymer).

Specific examples of the raw material monomer for obtaining the acrylic polymer include acrylic acid, methacrylic acid, crotonic acid, ethylene acetic acid, tiglic acid, and 2-trifluoromethacrylic acid. , acetyl acids such as itaconic acid, fumaric acid, maleic acid, citraconic acid, mesaconic acid, and gluconic acid; sulfonate such as 2-acrylamido-2-methylpropanesulfonic acid Acids; methyl acrylate, butyl acrylate, methyl methacrylate, and methacrylic acid An ester such as a butyl ester; and a salt such as an ammonium salt, an alkali metal salt or an alkylamine salt.

In the above, the polishing liquid for CMP is preferably a methacrylic polymer (polymer obtained by polymerizing or copolymerizing a raw material monomer containing methacrylic acid as a monomer component). The methacrylic polymer is preferably at least one selected from the group consisting of a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid.

When the methacrylic polymer is a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid, the ratio of methacrylic acid to the total amount of the monomers is preferably 40 mol% or more, more preferably 70 mol. More than 8% of the ear. Further, the aforementioned ratio is preferably less than 100 mol%. That is, the aforementioned ratio is preferably 40 mol% or more and less than 100 mol%, more preferably 70 mol% or more and less than 100 mol%. By increasing the ratio of the methacrylic acid, corrosion and cracking can be further suppressed, and the flatness of the surface to be polished can be further improved. When the ratio of the methacrylic acid is less than 40 mol%, corrosion and cracks may not be effectively suppressed, and the flatness of the surface to be polished tends to be lowered.

In the case where the stability of the cerium oxide particles contained in the polishing liquid for CMP is extremely lowered, and the flatness is further improved, the total amount of all the components of the polishing liquid for CMP is 100 parts by mass, and the methyl group is used. The amount of the acrylic polymer to be blended is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.1 part by mass or less, and particularly preferably 0.05 part by mass or less. The lower limit is preferably 0.001 part by mass or more, more preferably 0.05 part by mass or more, and still more preferably 0.01 part by mass or more, based on 100 parts by mass of the polishing liquid for CMP.

According to the polishing liquid for CMP of the present embodiment, the barrier material and the ceria material can be polished at a high speed even with a relatively small amount of the ceria particles added, which is advantageous in terms of cost. Of course, the cerium oxide particles can be added in a large amount without being affected by aggregation or sedimentation. However, in the polishing liquid for CMP of the present embodiment, the amount of the cerium oxide particles added may be small, and since the dispersibility of the cerium oxide particles is also extremely high, for example, the polishing liquid for CMP is transported and stored. It can be concentrated to a high concentration. That is, the "slurry" containing at least the cerium oxide particles and one or a plurality of "addition liquids" or "dilutions" containing the components other than the cerium oxide particles are separately prepared and stored in the CMP polishing step. It can be modulated by mixing these.

(separate storage)

The polishing rate can be adjusted to a more preferable value by including a component such as the metal dissolving agent described above, but the dispersion stability of the cerium oxide particles may be lowered by mixing these in advance in the polishing liquid. In order to avoid this, the polishing liquid for CMP of the present embodiment can be separated into a slurry containing the cerium oxide particles and a component other than the cerium oxide particles (for example, the dispersion of the cerium oxide particles can be stabilized). The added liquid of the reduced component is prepared and stored. For example, when the polishing liquid for CMP contains the above-mentioned cerium oxide particles, a metal solvating agent, a metal oxidizing agent, a metal corrosion inhibitor, and water, the metal oxidizing agent which may affect the dispersion stability of the cerium oxide particles may be stored separately from the cerium oxide particles. . That is, it can be separated into: an additive liquid containing a metal oxidizing agent; and a slurry containing cerium oxide particles, a metal dissolving agent, a metal corrosion inhibitor, and water.

(concentrated storage)

Since the sterol group density, the aspect ratio, and the boundary potential of the cerium oxide particles used in the polishing liquid for CMP of the present embodiment are within the ranges described above, the barrier material can be polished at a high speed even with a relatively small amount. And the cerium oxide material, therefore, can be contained and dispersed in the medium at a high concentration. In the conventional cerium oxide particles, the dispersibility is improved by a known method, and the content of up to about 10 parts by mass is limited to 100 parts by mass of the medium, and when it is added in this range, aggregation and sedimentation are caused. However, the cerium oxide particles used in the polishing liquid for CMP of the present embodiment can be dispersed in 10% by mass or more in the medium, and can be easily contained and dispersed in the medium within about 15 parts by mass. Further, it may contain and disperse up to about 18 parts by mass. This means that the polishing liquid for CMP of the present embodiment can be stored and transported by using a storage liquid for polishing liquid for CMP in a highly concentrated state, which is extremely advantageous in the process. For example, when used as a polishing liquid for CMP containing 5 parts by mass of cerium oxide particles, it means that it can be concentrated three times during storage and transportation. In this way, the polishing liquid for CMP of the present embodiment can be stored and transported as a storage liquid for a polishing liquid for CMP which is three times or more concentrated when used.

More specifically, for example, it is a storage liquid for a polishing liquid for CMP containing at least 10 parts by mass or more of the above-mentioned ceria particles, and an additive liquid containing the other components, in an amount of at least 10 parts by mass or more based on 100 parts by mass of the storage liquid for polishing liquid for CMP. And the preparation liquid is prepared as a desired polishing liquid for CMP by mixing the mixture before the polishing step or by supplying the concentration to the desired concentration during polishing. The diluent may, for example, be a liquid medium such as water, an organic solvent, or a mixed solvent of water and an organic solvent. Further, the diluent may contain components other than the cerium oxide particles, and may be, for example, a storage solution for a polishing liquid for CMP, a hydrogen peroxide aqueous solution as a diluent containing a metal oxidizing agent, and the like. Additives for ingredients. Even if the above-mentioned addition liquid and diluent are not separated, and the dispersion stability is not inhibited, the two liquids may be used in combination. Further, in the present embodiment, it is preferable to use a stock solution containing cerium oxide particles and water, an additive liquid containing other components, and a diluent.

(VI. Use and method of use)

The polishing liquid for CMP of the present embodiment as described above can be applied to a polishing step for manufacturing a semiconductor substrate or an electronic device. More specifically, it can be applied to wiring formation on a semiconductor substrate. For example, it can be used for CMP polishing of a substrate including a metal for a wiring portion, a barrier material, and an insulating material.

As a specific polishing method using the polishing liquid for CMP of the present embodiment, a polishing method in which a substrate is provided with a low-k material and a cerium oxide material coated with low-k is exemplified. At least a part of the material; and comprising a polishing step of polishing the ceria material to expose the 10-wk material, and performing polishing in the polishing step while supplying the polishing liquid for CMP.

Moreover, as another specific polishing method using the polishing liquid for CMP of the present embodiment, a polishing method is disclosed, which is a method of polishing a substrate having a low-k material having a concave portion and a convex portion on one surface. a cerium oxide material covering a convex portion of a low-k material; a barrier material covering the low-k material and the cerium oxide material; and a metal for the wiring portion covering the barrier material and filling the concave portion; The grinding method package And a first grinding step of grinding the wiring portion with a metal to expose the barrier material on the convex portion; and a second grinding step of grinding the barrier material on the convex portion and the ruthenium dioxide to expose the convex portion, wherein In the second polishing step, polishing is performed while supplying the polishing liquid for CMP. Further, in the second grinding step, a part of the convex portion of the low-k material is further polished to be flattened, that is, so-called over-polishing.

Further, the polishing liquid for CMP of the present embodiment can be prepared in a concentrated state and stored as a storage liquid for the polishing liquid for CMP. As a polishing method at this time, a polishing method which is a method of polishing a substrate, the substrate includes a low-k material having a concave portion and a convex portion on one surface, and a cerium oxide material covering the low-k a convex portion of the material; a barrier material covering the low-k material and the ceria material; and a metal for the wiring portion covering the barrier material and filling the recess; and the polishing method includes: a first grinding step, grinding a metal for the wiring portion to expose the barrier material on the convex portion; and a second grinding step of polishing the barrier material on the convex portion and the ceria material to expose the convex portion, wherein in the second grinding step, The CMP polishing liquid is obtained by supplying a polishing liquid for CMP with a diluent, an addition liquid, or both, while supplying a polishing liquid for CMP. In this case, as a method of preparing the polishing liquid for CMP, a storage method, a diluent, an addition liquid, and the like for the polishing liquid for CMP are supplied to each of the pipes in the second polishing step. Mixing in the system of the second grinding step. Further, before the second polishing step, a mixing step of mixing the storage liquid for the CMP polishing liquid, the diluent, the addition liquid, and the like may be provided. A polishing liquid for CMP is prepared.

Examples of the metal for the wiring portion include a copper-based metal such as copper, a copper alloy, an oxide of copper, and an oxide of a copper alloy; a tungsten-based metal such as tungsten, tungsten nitride, or a tungsten alloy; and silver. , gold and other substances as the main components. Among them, a metal containing a copper-based metal as a main component is preferable, and a metal containing copper as a main component is more preferable. The metal for the wiring portion can be formed by a known sputtering method, plating method, or the like. In addition, the "main component" means a component containing 50% by mass or more based on all components.

Examples of the insulating material include a lanthanoid material and an organic polymer. Further, a recess is formed on one surface of the insulating material.

Examples of the lanthanoid-based material include an organic bismuth phosphate glass obtained by using cerium oxide (cerium oxide), fluoroquinone hydrochloride glass, trimethyl decane or dimethoxy dimethyl decane as a starting material. Porous organic tellurite glass, cerium oxynitride, and cerium oxide-based materials such as hydrogenated sesquioxanes; cerium carbide; cerium nitride; and carbon-added cerium oxide (SiOC).

Further, examples of the organic polymer material include organic silicate glass starting from trimethyl decane and all-aromatic ring-type low-k material (all-aromatic low dielectric constant insulating material). -k material (low dielectric constant material) and the like.

Among these materials, in particular, fluoroquinone hydrochloride glass, organic silicate glass, porous organic silicate glass, carbon-added cerium oxide (SiOC), and the like are suitably used as the low-k material. These materials are formed by chemical vapor deposition (CVD), spin coating, dip coating, or spray coating.

The barrier material is formed for preventing the metal of the wiring portion from diffusing into the insulating material and improving the adhesion between the insulating material and the metal for the wiring portion. Examples of such a barrier material include titanium-based metals such as titanium, titanium nitride, titanium alloys, and other titanium compounds; lanthanoid metals such as lanthanum, cerium nitride, cerium alloy, and other cerium compounds; A lanthanide-based metal such as an alloy; a cobalt-based metal such as cobalt or another cobalt alloy; and a manganese-based metal such as manganese or another manganese alloy, which may be used singly or in combination of two or more. Further, the barrier material may be a laminated film of two or more layers.

As the apparatus for polishing, for example, a general polishing apparatus having a holder capable of holding a substrate to be polished when being polished by a polishing pad, and a surface plate connected to a motor having a variable number of revolutions can be used. It is top grade and has a polishing pad attached. The polishing pad is not particularly limited, and a general non-woven fabric, a foamed polyurethane, a porous fluororesin or the like can be used.

The polishing conditions are not limited, and the rotation speed of the flat plate is preferably a low-speed rotation of 200 min ^-1 or less to prevent the substrate from flying out. The polishing pressure is preferably from 1 to 100 kPa, which is more suitable for satisfying: in the same substrate, the difference in CMP speed is small (in-plane uniformity of CMP speed) and the unevenness existing before polishing is eliminated to be flat (flat pattern Sexual), preferably 5 to 50 kPa.

During the polishing, the polishing liquid for CMP is continuously supplied to the polishing pad by a pump or the like. The supply amount is not limited, but it is preferred that the surface of the polishing pad is always covered with the polishing liquid for CMP. Preferably, after the substrate after the polishing is carefully washed in the running water, the water droplets adhering to the substrate are dropped by a spin-drying machine or the like, and then dried. That is, it is preferable to carry out the substrate cleaning step after performing the polishing step of the present embodiment.

Hereinafter, the polishing method of the present embodiment will be described in further detail with reference to a specific example of the step of forming the wiring layer in the semiconductor substrate shown in Fig. 2 . Furthermore, it is needless to say that the polishing method of the present embodiment is not limited thereto.

First, a substrate on which an insulating material is formed, on which a low-k material 6 made of an organic tantalate glass or the like is formed, and a coating layer made of ruthenium dioxide or the like is laminated on the upper surface thereof. 7 thus obtained. The substrate is subjected to surface processing of an insulating material by a known means such as resist layer formation or etching to obtain a substrate in which a concave portion (substrate exposed portion) having a specific pattern is formed. Further, a substrate is obtained, and the barrier material 2 made of tantalum or the like is coated on the surface of the insulating material, and the substrate is formed by vapor deposition, CVD or the like. In addition, as shown in Fig. 2(a), a metal for wiring portion 3 composed of a metal for wiring such as copper is formed by a method such as vapor deposition, plating, or CVD to fill the concave portion, thereby obtaining The substrate 110 of the polishing method of the present embodiment. Further, the insulating material, that is, the low-k material 6 and the cover layer 7, the barrier material 2, and the wiring portion metal 3 are preferably formed to have thicknesses of about 10 to 2,000 nm, 1 to 100 nm, and 10 to 2,500 nm, respectively.

Then, a first polishing step is performed which uses, for example, a first CMP polishing liquid having a polishing rate ratio of the wiring portion metal/barrier material sufficiently large (faster than the barrier material and the polishing rate of the wiring portion metal) The wiring portion metal 3 on the surface of the substrate 110 produced by the above method is polished by CMP. Thereby, as shown in FIG. 2(b), the substrate 210 having the desired conductor pattern exposed, the desired conductor pattern exposing the barrier material 2 of the convex portion on the substrate, and the metal for the wiring portion remaining in the recess portion are obtained. 3. According to the grinding conditions, there are In the case of the metal for the wiring portion, the metal for the wiring portion can be polished. It is also possible to use metal for the wiring part.

The second polishing step is performed by polishing the obtained substrate 210 using the polishing liquid for CMP (second polishing liquid for CMP) of the present embodiment. In the second polishing step, polishing is performed using the metal 3 for polishing the wiring portion, the barrier material 2, and the low-k material 6 constituting the insulating material and the second CMP polishing liquid of the ceria material 7. At this time, first, the wiring portion metal 3 of the exposed barrier material 2 and the partial recessed portion is removed by polishing, whereby the ceria material 7 under the barrier material 2 covering the convex portion is entirely exposed.

Further, in order to ensure more excellent flatness, excessive polishing is performed (for example, in the second polishing step, until the polishing time for obtaining the desired pattern is 100 seconds, in addition to the 100 second polishing, an additional 50 seconds of grinding is added. "Excessive polishing 50%" is performed to remove the convex cerium oxide material 7, the partial low-k material 6, and the wiring portion metal 3 of the partial concave portion, thereby completing the polishing, and obtaining the substrate 310 after the polishing. As shown in Fig. 2(c), the substrate 310 after the polishing is completed has a shape in which the wiring portion metal 3 serving as the metal wiring is embedded in the concave portion, and the wiring portion metal 3 and the low-k material 6 are borderped. The cross section of the barrier material 2 is exposed.

Here, the polishing liquid for CMP of the present embodiment may be used as the polishing liquid for the first CMP. However, in order to utilize the high-speed polishing of the ceria material, the polishing liquid can be polished while suppressing the polishing rate of the low-k material. The feature is preferably at least used as the second polishing liquid for CMP.

As a result, an insulating material and a second metal wiring are further formed on the formed metal wiring, and a semiconductor substrate (not shown) having a desired number of wiring layers can be manufactured by repeating the same procedure for a specific number of times.

As described above, according to the polishing liquid for CMP of the present embodiment, a semiconductor substrate, an electronic device, or the like which is produced by the above-described polishing method is provided. The semiconductor substrate, the electronic device, and the like manufactured thereby are excellent in refinement, thinning, dimensional accuracy, and electrical characteristics, and have high reliability.

[Examples]

Hereinafter, the present invention will be described by way of examples. However, the invention is not limited to the embodiments.

<Experiment 1>

Using the polishing liquid for CMP of the embodiment of the present invention, the polishing rate at the time of polishing various blanket substrates was examined.

[Preparation of polishing liquid for CMP]

(Preparation of storage solution for polishing liquid for CMP)

1.6 parts by mass of malic acid and 0.4 parts by mass of benzotriazole as a metal corrosion inhibitor were added to the container, and X parts by mass of ultrapure water was poured thereinto, and 0.1 mass part of polymethacrylic acid (PMAA) was further contained. In the manner of adding a 36.5 mass% aqueous solution of PMAA, and adding the mass fraction of the quaternary phosphonium salt shown in Tables 1 and 2, mixing and stirring to dissolve the components. Then, the colloidal cerium oxides shown in Tables 1 and 2 are prepared, and this is used as the cerium oxide particles, and the amount of the total amount of the mixture is 12.0 parts by mass, based on 100 parts by mass of the storage liquid for the polishing liquid for CMP. Thus, "the storage liquid for the polishing liquid for CMP" is obtained. Furthermore, due to the respective solid components of the aforementioned colloidal cerium oxide (two Since the content of the cerium oxide particles is different, X parts by mass of the above-mentioned ultrapure water is calculated and calculated so that the total of all the storage liquids is 100 parts by mass.

Further, the PMAA is a copolymer of methacrylic acid and acrylic acid (copolymerization ratio: 99/1), and the weight average molecular weight is 7,500.

(Preparation of polishing liquid for CMP)

300 parts by mass of ultrapure water was added to 100 parts by mass of the above-mentioned stock solution, and diluted to 4 times to obtain a "slurry". Then, 1.5 parts by mass (hydrogen peroxide is equivalent to 0.2 part by mass) of a 30% by mass aqueous hydrogen peroxide solution was added, mixed and stirred to obtain 401.5 parts by mass of a polishing liquid for CMP. The content of each component with respect to 100 parts by mass of the polishing liquid for CMP was calculated to be 0.4 parts by mass of malic acid, 0.1 part by mass of benzotriazole, 0.025 parts by mass of PMAA, and 3.0 parts by mass of colloidal cerium oxide particles. . The contents of the quaternary phosphorus salt relative to 100 parts by mass of the polishing liquid for CMP are shown in Tables 1 and 2.

[Evaluation of characteristics of polishing fluid for CMP]

In Tables 1 and 2, the characteristics of the CMP polishing liquid and the colloidal cerium oxide particles A to G were investigated as follows.

(1) Two-axis average primary particle size (R[nm])

The colloidal cerium oxide was dried to obtain an image observed by a scanning electron microscope. Select any 20 particles from the image obtained. As shown in Fig. 3, a rectangular shape (external rectangle) 11 which is externally connected to the selected particle 10 and has a long axis to be the longest is drawn, and the long axis of the circumscribed rectangle 11 is X, and the short axis is Y. The biaxial average primary particle diameter of one particle was calculated by (X + Y)/2. This operation was performed on any of the 20 particles, and the average value of the obtained values was obtained as the biaxial average primary particle diameter.

(2) aspect ratio

From the image obtained by the scanning electron microscope described above, arbitrary 20 particles were selected, and the aspect ratio X/Y was calculated from the values of the obtained long axis X and short axis Y, respectively, in the same manner as described above. This operation is performed on any of the 20 particles, and the average value of the obtained values is obtained as an aspect ratio.

(3) BET specific surface area S _BET [m ² /g]

The colloidal cerium oxide was sufficiently degassed at 250 ° C under vacuum and was obtained by a one-point method of adsorbing nitrogen gas using a BET specific surface area measuring device.

(4) Density of stanol groups (ρ[/nm ² ])

The liquid amount of the colloidal cerium oxide was measured so that the amount (A [g]) of the cerium oxide particles contained in the liquid was 1.5 g, and the pH was adjusted to 3.0 to 3.5 with hydrochloric acid. Thereafter, 30 g of sodium chloride was added, and ultrapure water was added to make the total amount 150 g. The pH was adjusted to 4.0 using a sodium hydroxide solution as a sample for titration.

The sodium hydroxide aqueous solution was added dropwise until the pH of the sample for titration became 9.0, and the amount of sodium hydroxide (B [mol]) required before the pH was changed from 4.0 to pH 9.0 was determined.

These two values are substituted with the values of the BET specific surface area (S _BET [m ² /g]) and the subfocal constant (N _A [mol/mol]) separately measured in the above (3). In 2), calculate the density of stanol groups.

ρ=B‧N _A /A‧S _BET ......(2)

In the formula (2), N _A [unit/mol] represents a argon-addition constant, and S _BET [m ² /g] represents a BET specific surface area of the cerium oxide particles.

(5) Jieda potential [mV]

As the measuring device, a Delsa Nano C manufactured by Beckman Coulter Inc. was used, and the CMP was diluted in such a manner that the scattering intensity of the measurement sample in the apparatus was 1.0 × 10 ⁴ to 5.0 × 10 ⁴ cps. The slurry is prepared to prepare a measurement sample. Specifically, the CMP slurry is diluted with pure water as a measurement sample, so that the colloidal cerium oxide particles contained in the polishing liquid for CMP are 1.71 parts by mass in 100 parts by mass of the polishing liquid for CMP. The measurement was carried out by placing it in the cell for potential measurement.

(6) pH

The pH (25 ° C) of the polishing liquid for CMP was measured using a model PH81 manufactured by Yokogawa Electric Corporation. Specifically, after using a standard buffer (phthalic acid pH buffer: pH 4.01 (25 ° C), neutral phosphate pH buffer: pH 6.86 (25 ° C)), after two-point calibration, The electrode was placed in a CMP slurry and passed for 2 minutes or more and stabilized. The pH of the polishing liquid of Comparative Example 6 was 2.4, and the pH of all the examples and comparative examples was 2.5.

[Evaluation of grinding speed using CMP slurry]

Using the polishing liquid for CMP obtained as described above, the polishing rate at the time of polishing the four kinds of cladding substrates (coating substrates (a) to (d)) under the following polishing conditions was examined.

(grinding conditions)

‧ Grinding and cleaning device: CMP grinder Reflexion LK (Applied Materials, Inc.)

‧ polishing pad: foamed polyurethane resin (product name: VP3100, manufactured by Rohm and Haas Co.)

‧ Flat plate rotation: 93 rev / min

‧ head rotation: 87 rev / min

‧ Grinding pressure: 10kPa

‧The supply amount of polishing liquid for CMP: 300mL/min

‧ Polishing time: coating substrate (a) 120 sec, cladding substrate (b) 30 sec, cladding substrate (c) 60 sec, and cladding substrate (d) 90 sec.

(coating substrate)

‧Laminated substrate (a): A tantalum substrate having a copper film having a thickness of 1600 nm formed by sputtering.

‧Laminated substrate (b): A tantalum substrate having a tantalum nitride film having a thickness of 2800 nm was formed by sputtering.

‧Laminated substrate (c): A tantalum substrate having a thickness of 1000 nm of a hafnium oxide film is formed by a CVD method.

‧Laminated substrate (d): A ruthenium substrate (BDIIX film manufactured by Advantech Co., Ltd.) having a thickness of 160 nm of SiOC film was formed by a CVD method.

(calculation of grinding speed)

The polishing rates of the four kinds of cladding substrates after polishing and cleaning were determined as follows. In other words, the thicknesses of the coating layers (a) and (b) before and after the polishing were measured using a metal film thickness measuring device (model VR-120/08S manufactured by Hitachi Kokusai Electric Co., Ltd.). And it is determined by the difference in film thickness. On the other hand, for the cladding substrates (c) and (d), the film thickness measuring device RE-3000 (manufactured by Dainippon Screen Mfg. Co., Ltd.) was used to measure the before and after the polishing. The film thickness is determined by the difference in film thickness. The measurement results of the respective polishing rates are shown in Tables 1 and 2.

[evaluation result]

It is understood from Tables 1 and 2 that the polishing liquid for CMP of Comparative Examples 1 and 2 does not sufficiently suppress the fourth-order sulfonium salt which is a quaternary phosphonium salt but does not have an aromatic ring bonded to a phosphorus atom. The polishing rate of the SiOC film of the cladding substrate (d).

In the polishing liquid for CMP of Comparative Example 3, since the quaternary phosphonium salt was not contained, the polishing rate of the SiOC film of the clad substrate (d) could not be sufficiently suppressed.

In the polishing liquid for CMP of Comparative Examples 4 and 5, since the ceria particles C and D having an aspect ratio of less than 1.3 are contained in the polishing liquid for CMP, at least the dioxide of the cladding substrate (c) cannot be sufficiently obtained. The grinding speed of the diaphragm. Further, it was found that the polishing rate of the SiOC film of the clad substrate (d) could not be sufficiently suppressed.

It is understood that the polishing liquid for CMP of Comparative Examples 6 to 8 has an aspect ratio of less than 1.3 including cerium oxide particles, and cerium oxide particles having a density of stanol groups of not 1.0 to 2.0 particles/nm ² or E or F or G, therefore, at least the polishing rate of the SiOC film of the clad substrate (d) is not suppressed.

In the polishing liquid for CMP of Comparative Examples 9 to 13, since the ratio of the content of the cerium oxide particles to the content of the quaternary phosphonium salt is less than 750, at least the copper film of the cladding substrate (a) cannot be sufficiently obtained. Grinding speed.

In contrast, the polishing liquid for CMP of Examples 1 to 5 contains cerium oxide particles and a quaternary phosphonium salt having an aromatic ring bonded to a phosphorus atom, and the aspect ratio of the cerium oxide particles is 1.3 or more. The stanol group has a density of 1.0 to 2.0 pieces/nm ² and an interface potential of +10 mV or more, and the ratio of the content of the cerium oxide particles to the content of the quaternary phosphonium salt is 750 or more. Therefore, a good polishing rate can be obtained for the copper film of the cladding substrate (a), the tantalum nitride film of the cladding substrate (b), and the ceria film of the cladding substrate (c), and the coating can be suppressed. The polishing rate of the SiOC film of the substrate (d). Further, in any of the examples, the dispersion stability of the polishing liquid (long-term dispersibility of the cerium oxide particles) was excellent.

<Experiment 2>

The polishing liquid for CMP according to the embodiment of the present invention was used to investigate the amount of polishing, the amount of corrosion, and the amount of cracking of the insulating material when the pattern substrate of the copper wiring was polished.

[Preparation of polishing liquid for CMP]

The polishing liquid for CMP of Example 3 and Comparative Examples 1, 3 and 6 produced in Experiment 1 was used. Further, the polishing conditions were the same as in Experiment 1. A pattern substrate having a diameter of 12 inches (30.5 cm) (φ) was prepared as a substrate for evaluation. This pattern substrate was produced as follows.

First, a SiOC film having a thickness of 150 nm was laminated on a substrate. Further, processing is performed by means of resist layer formation, etching, or the like to form a concave portion (groove 160 nm) of a specific pattern on the surface of the tantalum substrate. Then, a tantalum nitride film of 10 nm and a ruthenium film of 10 nm were sequentially formed to serve as a barrier material for coating the surface along the unevenness. In addition, a metal for a wiring portion made of copper at 660 nm was formed so as to fill the concave portion, and a pattern substrate used in the polishing method of Experiment 2 was prepared.

[Various Evaluation of Pattern Substrate after CMP Polishing]

The pattern substrate is polished using a known abrasive for copper polishing until the barrier material is exposed. Then, while the prepared CMP polishing was dropped onto the spacer attached to the flat plate of the polishing apparatus, the pattern substrate on which the barrier material was exposed was polished under the above-described polishing conditions. Furthermore, it has a wiring width of 100 μm In the pattern region of the copper wiring portion and the insulating material portion having a wiring width of 100 μm, the timing at which the disk trapping amount of the copper wiring portion is 100 Å or less is used as the end point of polishing. The amount of polishing, the amount of corrosion, and the amount of cracking of the insulating material after the completion of the grinding were evaluated as follows. The evaluation results are shown in Table 3.

(Evaluation of the amount of grinding of the insulating material)

In the patterned substrate after polishing, the amount of polishing of the insulating material (SiOC film) in the region free of copper wiring was measured by a desktop type optical interference type film thickness measuring system NanoSpec M5000 (manufactured by Nanometrics Inc.).

(corrosion assessment)

In the patterned substrate after polishing, a copper wiring portion having a wiring width of 13 μm and a pattern region of an insulating material portion having a wiring width of 7.5 μm ("L/S = 13/7.5" in the table) and a wiring width were respectively measured. The amount of corrosion in the pattern region of the 13 μm copper wiring portion and the insulating material portion having a wiring width of 2.5 μm ("L/S = 13/2.5" in the table). In addition, the amount of corrosion was scanned by a contact step meter (P-16 manufactured by KLA-Tencor Corporation), and the film thickness of the insulating material portion and the film thickness of the copper wiring portion were measured. The difference is to find.

(crack assessment)

In the patterned substrate after polishing, a copper wiring portion having a width of 100 μm and a pattern region of an insulating material portion having a width of 100 μm ("L/S=100/100" in the table) and copper having a wiring width of 13 μm were respectively measured. The amount of cracks in the pattern portion ("L/S = 13/7.5" in the table) of the wiring portion and the insulating material portion having a wiring width of 7.5 μm. Furthermore, the amount of cracks is scanned by a contact step meter (P-16 manufactured by KLA-Tencor Co., Ltd.) and measured by copper wiring. The near insulating material portion is obtained by the amount of stepping of the overgrinding.

[evaluation result]

As is apparent from Table 3, the polishing liquid for CMP of Comparative Example 1 contains a quaternary phosphonium salt which is a quaternary phosphonium salt but does not have an aromatic ring bonded to a phosphorus atom, so that the amount of corrosion and the amount of cracks increase. .

It was found that the polishing liquid for CMP of Comparative Example 3 does not contain the above-described quaternary phosphonium salt, and therefore the amount of corrosion and the amount of cracks increase.

In the polishing liquid for CMP of Comparative Example 6, since the cerium oxide particles having an aspect ratio of less than 1.3 and a sterol group density of not more than 1.0 to 2.0/nm ^{2 are} contained, the polishing amount of the SiOC film is large, and The amount of corrosion and the amount of cracks increase.

I know that, as the abrasive objects are separated by wiring, The substrate (for example, L/S=100/100) is converted into a narrow substrate (for example, L/S=13/85~13/2.5), and from the viewpoint of cracking and corrosion, the comparative example (previously equivalent) It is extremely difficult to sufficiently ensure the flatness of the polishing liquid for CMP.

In contrast, the polishing liquid for CMP of Example 3 contains cerium oxide particles A and a quaternary phosphonium salt having an aromatic ring bonded to a phosphorus atom, and the cerium oxide particle A Since the aspect ratio is 1.3 or more and the stanol group density is 1.0 to 2.0 pieces/nm ² , the polishing amount of the SiOC film is small in the polishing of the substrate having a narrow wiring interval, and the amount of corrosion and the amount of cracks are sufficiently suppressed.

2‧‧‧Blocking materials

3‧‧‧Metal for wiring department

5‧‧‧矽 substrate

6‧‧‧low-k material (insulation material)

7‧‧‧ Coverage

110, 210, 310‧‧‧ substrates

Claims (18)

A polishing liquid for CMP comprising cerium oxide particles, a quaternary phosphonium salt having at least one aromatic ring bonded to a phosphorus atom, and water, wherein the cerium oxide particles have a sterol group density of 1.0 to 2.0/ In the case of nm ² , the aspect ratio is 1.3 or more, and the boundary potential in the polishing liquid for CMP is +10 mV or more, and the ratio of the content of the cerium oxide particles to the content of the quaternary phosphonium salt is 750 or more. The polishing liquid for CMP according to claim 1, wherein the quaternary phosphonium salt is a compound represented by the following formula (1). [In the formula (1), R represents an alkyl group or an aryl group which may have a substituent, and X ^- represents an anion]. The polishing slurry for CMP according to claim 1 or 2, wherein the quaternary phosphonium salt is selected from the group consisting of butyl triphenyl phosphonium salt, pentyl triphenyl phosphonium salt, hexyl triphenyl phosphonium salt, and n-heptyl group. At least one of the group consisting of triphenylsulfonium salt, tetraphenylphosphonium salt, and benzyltriphenylphosphonium salt. The polishing liquid for CMP according to any one of claims 1 to 3, wherein the content of the quaternary phosphonium salt is 0.0005 parts by mass or more and less than 0.005 parts by mass based on 100 parts by mass of the polishing liquid for CMP. The polishing slurry for CMP according to any one of claims 1 to 4, wherein The aforementioned cerium oxide particles are colloidal cerium oxide particles. The polishing liquid for CMP according to any one of claims 1 to 5, wherein the content of the cerium oxide particles is 1.0 to 15.0 parts by mass based on 100 parts by mass of the polishing liquid for CMP. The polishing liquid for CMP according to any one of claims 1 to 6, wherein the pH is 6.0 or less. The polishing liquid for CMP according to any one of claims 1 to 7, further comprising a metal dissolving agent. The polishing slurry for CMP according to any one of claims 1 to 8, which further contains a metal oxidizing agent. The polishing slurry for CMP according to any one of claims 1 to 9, which further contains a metal corrosion inhibitor. The polishing slurry for CMP according to claim 10, wherein the metal corrosion inhibitor is a triazole compound. The polishing liquid for CMP according to any one of claims 1 to 11, further comprising a water-soluble polymer. The polishing liquid for CMP according to any one of claims 1 to 12, further comprising an organic solvent. A storage liquid for obtaining the polishing liquid for CMP according to any one of claims 1 to 13, and obtaining the aforementioned polishing liquid for CMP by dilution with a liquid medium. A polishing method, which is a method of polishing a substrate, the substrate comprising: a low-k material; and a cerium oxide material covering at least a portion of the low-k material; And a polishing step of polishing the ruthenium dioxide material to expose the low-k material, and polishing the CMP polishing liquid according to any one of claims 1 to 13 in the polishing step. A polishing method for a substrate, the substrate comprising: a low-k material having a concave portion and a convex portion on one side; a cerium oxide material covering the convex portion of the low-k material; and a barrier material And coating the low-k material and the cerium oxide material; and a metal for wiring portion covering the barrier material and filling the concave portion; and the polishing method includes: a first polishing step of grinding the wiring portion Using a metal to expose the barrier material on the convex portion; and a second polishing step of polishing the barrier material on the convex portion and the cerium oxide material to expose the convex portion; In the second polishing step, the polishing liquid for CMP according to any one of claims 1 to 13 is supplied while being polished. The polishing method according to claim 16, wherein the metal for the wiring portion is a metal containing copper as a main component. The grinding method of claim 16 or 17, wherein the barrier material comprises a material selected from the group consisting of niobium, tantalum nitride, niobium alloy, titanium, titanium nitride, titanium alloy, niobium, tantalum alloy, cobalt, cobalt alloy, manganese, and At least one of the group consisting of manganese alloys.