TW201615778A - Aqueous dispersion for chemical mechanical polishing and chemical mechanical polishing method - Google Patents

Abstract

Provided are: an aqueous dispersion for chemical mechanical polishing, which contains silica particles and is capable of polishing a silicon oxide film at a higher rate than conventional aqueous dispersions for chemical mechanical polishing in a process wherein a surface to be polished having the silicon oxide film is polished; and a chemical mechanical polishing method which uses this aqueous dispersion for chemical mechanical polishing. An aqueous dispersion for chemical mechanical polishing according to the present invention is characterized by containing silica particles that satisfy the conditions (1)-(3) described below and by having a pH of from 2 to 5 (inclusive). (1) The silica particles have an average particle diameter of 30 nm or more as determined by means of a transmission electron microscope. (2) The silica particles have a [xi] potential of +5 mV or more at a pH of from 2 to 5 (inclusive). (3) The silica particles have chained spherical shapes obtained by connecting a plurality of silica particles that are primary particles, or alternatively have recessed and projected shapes.

Description

Chemical mechanical polishing water dispersion and chemical mechanical polishing method

The present invention relates to a chemical mechanical polishing aqueous dispersion and a chemical mechanical polishing method.

The chemical film polishing (hereinafter also referred to as "CMP") is applied to the polishing of the film to be processed, as the semiconductor device is increased in thickness and multilayer wiring is used. It is a groove, a hole, or the like of a desired pattern formed in an insulating film on a process wafer, and a suitable wiring material is buried, and then chemical mechanical polishing is used to remove excess wiring material to form a wiring. In addition to forming wiring, the CMP is also applied to the formation of capacitors, gate electrodes, etc., and is also used for mirror polishing of silicon wafers such as SOI (Silicon On Insulator) substrates. The object to be polished by CMP is classified into a polysilicon film, a single crystal germanium film, a tantalum oxide film, aluminum, tungsten, copper, or the like.

These intermediate oxide films are generally utilized as an interlayer insulating film. The CMP process of the tantalum oxide film not only requires the planarization property of the interlayer insulating film, but also requires less scratch damage such as scratches and a high polishing rate.

The chemical mechanical polishing aqueous dispersion used for CMP of the tantalum oxide film used the cerium oxide particles as the abrasive particles. As a method for producing such cerium oxide particles, for example, a particle growth method in which an alkyl citrate hydrolyzate is continuously added to alkaline hot water is known. For example, Patent Document 1 discloses that cerium oxide particles which are grown by removing sodium from a sodium citrate aqueous solution (water glass) by an ion exchange resin or the like are formed. In the particle growth method, since an active aqueous solution of citric acid is added under alkaline conditions, it is spherical and monodisperse, and tends to form dense cerium oxide particles.

In recent years, it has been reviewed to shape the spherical monodisperse cerium oxide (i.e., to become a secondary particle of a complicated shape), and to adjust the contact resistance of the surface to be polished when used as an abrasive, thereby further improving the polishing speed ( Refer to, for example, Patent Document 2).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-197573

[Patent Document 2] Japanese Patent No. 5127452

However, as described above, the cerium oxide particles have a negative zeta potential in the alkaline region, but since the isoelectric point is near pH 2, it is a negative value even in the acidic region. On the other hand, the surface of the tantalum oxide film is also considered to be the same as the above-mentioned cerium oxide particles in the same pH region. The value of the bit. Therefore, the chemical mechanical polishing aqueous dispersion containing the above-described cerium oxide particles has a problem that the ruthenium oxide film cannot be polished at a high speed due to the electrostatic repulsion (repulsive force) of the surface of the ruthenium oxide film and ruthenium dioxide.

Therefore, in order to solve the above problems, the present invention provides a chemical mechanical polishing containing cerium oxide particles which can polish the cerium oxide film at a higher speed than in the prior art in the step of polishing the surface to be polished having the ruthenium oxide film. A water-based dispersion, and a chemical mechanical polishing method using the same.

The present invention is to solve at least some of the above problems, and can be implemented by the following aspects or application examples.

[Application Example 1]

The chemical mechanical polishing aqueous dispersion of the present invention is characterized by containing cerium oxide particles satisfying the following conditions (1) to (3), and having a pH of 2 or more and 5 or less:

(1) The average particle diameter measured by a transmission electron microscope is 30 nm or more.

(2) The zeta potential of the entire range of pH 2 to 5 is +5 mV or more.

(3) A chain shape having a plurality of bonds of cerium oxide particles as primary particles or having a concavo-convex shape.

[Application Example 2]

In the chemical mechanical polishing aqueous dispersion of Application Example 1, the aforementioned dioxin The cerium oxide particles may be cerium oxide particles produced by a sol-gel method.

[Application Example 3]

In the chemical mechanical polishing aqueous dispersion of Application Example 1 or Application Example 2, an organic acid is further contained.

[Application Example 4]

A chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 3, which is used for polishing a surface to be polished having a tantalum oxide film.

[Application 5]

The chemical mechanical polishing method of the present invention is characterized in that the surface to be polished having the tantalum oxide film is polished using the chemical mechanical polishing aqueous dispersion of any one of Application Examples 1 to 4.

According to the chemical mechanical polishing aqueous dispersion of the present invention, in the step of polishing the surface to be polished having the tantalum oxide film, the tantalum oxide film can be polished at a higher speed than the conventional chemical mechanical polishing aqueous dispersion.

10‧‧‧矽 substrate

12‧‧‧矽Nitride film

14‧‧‧Ditch

16‧‧‧矽Oxide film

42‧‧‧ slurry supply nozzle

44‧‧‧Slurry

46‧‧‧ polishing cloth

48‧‧‧ Turntable

50‧‧‧Semiconductor substrate

52‧‧‧ Carrying head

54‧‧‧Water supply nozzle

56‧‧‧Finisher

100‧‧‧Processed body

200‧‧‧Chemical mechanical grinding device

Fig. 1 is a cross-sectional view schematically showing an object to be processed which can be used in the chemical mechanical polishing method of the embodiment.

Fig. 2 is a cross-sectional view for explaining a polishing step of the chemical mechanical polishing method of the embodiment.

Fig. 3 is a perspective view schematically showing a chemical mechanical polishing apparatus.

Hereinafter, preferred embodiments of the present invention will be described in detail. The present invention is not limited to the embodiments described below, and various modifications may be made without departing from the spirit and scope of the invention.

1. Chemical mechanical polishing water dispersion

A chemical mechanical polishing aqueous dispersion system according to an embodiment of the present invention is a chemical mechanical polishing aqueous dispersion for polishing a surface to be polished having a ruthenium oxide film, which is characterized by containing cerium oxide particles satisfying specific conditions (hereinafter, It is called "specific cerium oxide particles" and has a pH of 2 to 5. Hereinafter, each component contained in the chemical mechanical polishing aqueous dispersion of the present embodiment will be described.

1.1. Specific cerium oxide particles

The chemical mechanical polishing aqueous dispersion of the present embodiment contains specific cerium oxide particles satisfying the following conditions (1) to (3):

(1) The average particle diameter measured by a transmission electron microscope is 30 nm or more.

(2) The zeta potential of any of pH 2 or higher and 5 or less is +5 mV or more.

(3) a plurality of bonds of cerium oxide particles having primary particles are formed Chain-shaped, or have a concave-convex shape.

High-speed polishing of the tantalum oxide film can be achieved by containing specific niobium oxide particles satisfying the three conditions.

<Condition (1): Average particle diameter>

The specific particle diameter of the specific cerium oxide particles measured by a transmission electron microscope image must be 30 nm or more, preferably 30 nm or more and 500 nm or less, more preferably 30 nm or more and 200 nm or less. By subjecting the specific particle diameter of the specific cerium oxide particles to 30 nm or more, high-speed polishing of the ruthenium oxide film can be achieved. On the other hand, when the average particle diameter is less than 30 nm, the polishing rate of the ruthenium oxide film may be insufficient, and the gelation tends to be unsettled at the time of production.

The "average particle diameter measured by a transmission electron microscope image" is an average particle diameter calculated by performing image analysis on an image captured by a transmission electron microscope. In the present invention, the Heywood diameter of 50 particles was measured and the average value was calculated.

The device of the transmission electron microscope is an equivalent electron microscope "H-7650" manufactured by Hitachi High-Tech Co., Ltd., and "JEM-2100" manufactured by JEOL Ltd. The software used for image analysis is exemplified by the image analysis type particle size distribution measurement software "Mac-View ver. 4" manufactured by MOUNTECH.

<Condition (2): zeta potential>

Specific cerium oxide particles at any value above pH 2 and below 5 The bit must be +5 mV or more, preferably +5 mV or more + 50 mV or less. When the zeta potential of any of the specific cerium oxide particles of pH 2 or more and 5 or less is +5 mV or more, it is not easy to make specific cerium oxide particles based on the attraction force of electrostatic interaction between the specific cerium oxide particles and the cerium oxide film. The surface of the tantalum oxide film is localized, so that high-speed polishing of the tantalum oxide film can be achieved. When the zeta potential is less than +5 mV, the electrostatic interaction between the specific cerium oxide particles and the cerium oxide film becomes small or the repulsion acts, so that the polishing rate of the cerium oxide film is insufficient. The cerium oxide particles having a zeta potential of +5 mV or more can be obtained, for example, by modifying a cerium oxide particle with a decane coupling agent having an amine group.

The zeta potential of a specific cerium oxide particle can be measured by a usual method by using a laser Doppler method as a measuring principle of a zeta potential measuring device. The zeta potential measuring device is exemplified by a "spot potential analyzer" manufactured by Brookhaven Instruments Co., Ltd., "ELSZ-1000ZS" manufactured by Otsuka Electronics Co., Ltd., and the like.

<Condition (3): Shape>

The shape of the specific cerium oxide particles must have a chain shape in which a plurality of primary cerium oxide particles are joined, or have a concave-convex shape. When the shape of the specific cerium oxide particles is a chain shape or a concavo-convex shape, the contact resistance with the surface to be polished (that is, the ruthenium oxide film) is increased, and high-speed polishing of the ruthenium oxide film can be realized.

In the present specification, the term "chain-like" means that three or more particles can be combined into one or a plurality of columns, and not only a linear structure. It also contains branching constructs. Further, the term "concave-convex shape" means a shape that is deformed, that is, a secondary particle in which a plurality of particles are formed into a complicated shape, and does not include a monodisperse spherical primary particle or a secondary particle to form a spherical shape.

The content of the specific cerium oxide particles is preferably 1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and most preferably 1% by mass based on the total mass of the chemical mechanical polishing aqueous dispersion. The above 10% by mass or less. When the content of the specific cerium oxide particles is within the above range, high-speed polishing of the cerium oxide film can be achieved, and the storage stability of the chemical mechanical polishing aqueous dispersion is good.

Since the chemical mechanical polishing aqueous dispersion of the present embodiment is used for polishing the tantalum oxide film used in the manufacture of a semiconductor device, it is necessary to avoid metal contamination of the surface to be polished by polishing. Therefore, 1) sodium of specific ceria particles, 2) is selected from the group consisting of alkaline earth metals composed of calcium and magnesium, and 3) is selected from the group consisting of iron, titanium, nickel, chromium, copper, zinc, lead, silver, manganese. The content of the heavy metals in the group consisting of cobalt and cobalt is preferably 1 ppm or less.

These specific cerium oxide particles are not produced by the water glass method or the Stober method, but are produced by a sol-gel method. For example, it can be produced according to the manufacturing method described in International Publication No. 2010/035613. When a specific cerium oxide particle is produced, since the zeta potential must be set to +5 mV or more, it is preferable to adsorb the amine on the surface of the cerium oxide particle to carry out surface treatment. A known method of making the zeta potential positive is also a method of treating aluminum. However, since the above-mentioned problem of metal contamination occurs, it is not preferable to use it in the use of electric materials.

1.2. Organic acids

In the chemical mechanical polishing aqueous dispersion of the present embodiment, the pH may be adjusted to 2 or more and 5 or less by adding an organic acid or phosphoric acid to be described later. Even if an organic acid other than phosphoric acid is added, the pH can be made acidic. However, since the above-mentioned metal contamination is caused, it is limited to use in electrical materials. In the case of an organic acid or phosphoric acid, the surface to be polished is not contaminated by metal, and the pH can be adjusted.

The organic acids are listed, for example, as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, isoprenesulfonic acid, gluconic acid, lactic acid, glycolic acid, malonic acid, formic acid, oxalic acid, succinic acid, fumaric acid, Maleic acid, phthalic acid, etc. These organic acids may be used alone or in combination of two or more.

1.3. Dispersing media

The chemical mechanical polishing aqueous dispersion of the present embodiment contains a dispersion medium. The dispersion medium is exemplified by water, a mixed medium of water and alcohol, a mixed medium containing water and an organic solvent having compatibility with water, and the like. Among these, a mixed medium of water, water and alcohol is preferably used, and water is preferably used.

1.4. pH

The pH of the chemical mechanical polishing aqueous dispersion of the present embodiment is 2 or more and 5 or less, preferably 2 or more and 4 or less. By setting the pH to a range of 2 or more and 5 or less, the zeta potential of the specific cerium oxide particles can be made a positive charge. Accordingly, the specific cerium oxide particles are not caused by the attraction of the electrostatic interaction between the negatively charged cerium oxide film and the specific cerium oxide particles. It is easy to localize the surface of the oxide film, so that high-speed polishing of the tantalum oxide film can be achieved. When the pH is more than 5, the zeta potential of the specific cerium oxide particles tends to be negative, and it is difficult to achieve high-speed polishing due to the electrostatic repulsion of the ruthenium oxide film and the specific ruthenium dioxide particles.

1.5. Other additives

In the chemical mechanical polishing aqueous dispersion of the present embodiment, a surfactant, a water-soluble polymer, phosphoric acid or a derivative thereof may be added as needed.

<Surfactant>

The surfactant is exemplified by, for example, a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and the like.

The cationic surfactant is exemplified by, for example, an aliphatic amine salt, an aliphatic ammonium salt, and the like.

The anionic surfactant is exemplified by, for example, a carboxylate, a sulfonate, a sulfate, a phosphate or the like. The carboxylate is exemplified by a fatty acid soap, an alkyl ether carboxylate or the like. The sulfonate is exemplified by an alkylbenzenesulfonate, an alkylnaphthalenesulfonate, an α-olefinsulfonate or the like. Sulfate salts are exemplified by, for example, higher alcohol sulfate salts, alkyl sulfate salts, and the like. The phosphate ester is exemplified by, for example, an alkyl phosphate.

Examples of the nonionic surfactant include an ether type surfactant, an ether ester type surfactant, an ester type surfactant, an acetylene surfactant, and the like. Ether ester type surfactants are exemplified by polyoxygenates such as glycerol esters. Ethyl ether and the like. The ester type surfactant is exemplified by, for example, a polyethylene glycol fatty acid ester, a glycerin ester, a sorbitan ester or the like. The acetylene-based surfactant is exemplified by an acetylene alcohol, an acetylene glycol, an ethylene oxide adduct of acetylene glycol, or the like.

The amphoteric surfactant is exemplified by, for example, a betaine surfactant.

These surfactants may be used alone or in combination of two or more.

Among these surfactants, an anionic surfactant is preferred, and a sulfonate is preferred. Further, the sulfonate is preferably an alkylbenzenesulfonate, more preferably a dodecylbenzenesulfonate.

The content of the surfactant is preferably 1% by mass or less, more preferably 0.001 to 0.1% by mass based on the total mass of the chemical mechanical polishing aqueous dispersion. When the amount of the surfactant added is within the above range, a smooth polished surface can be obtained after polishing and removing the tantalum oxide film.

<Water-soluble polymer>

The water-soluble polymer has a function of adsorbing on the surface of the surface to be polished to reduce polishing friction. Accordingly, by adding a water-soluble polymer, it is possible to suppress the occurrence of dents or corrosion.

The water-soluble polymer may, for example, be polyacrylamide, polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone or hydroxyethylcellulose.

The amount of water-soluble polymer can be adjusted to make chemical machinery The viscosity of the aqueous dispersion for grinding was less than 2 mPa ‧ s. When the viscosity of the chemical mechanical polishing aqueous dispersion exceeds 2 mPa ‧ , the polishing rate is lowered, and when the viscosity is too high, the chemical mechanical polishing aqueous dispersion cannot be stably supplied to the polishing cloth. As a result, the temperature of the polishing cloth rises or the unevenness of the polishing (the in-plane uniformity is poor) or the like occurs, and the polishing rate or the variation of the depression occurs.

<phosphoric acid or its derivatives>

In the chemical mechanical polishing aqueous dispersion of the present embodiment, phosphoric acid or a derivative thereof may be added as needed. By adding phosphoric acid or a derivative thereof, it is possible to adjust not only the pH to 2 or more and 5 or less, but also the polishing rate of the tantalum oxide film. This is estimated by the synergistic effect of the chemical polishing action of phosphoric acid on the ruthenium oxide film and the mechanical polishing action of the specific cerium oxide particles.

The content of the phosphoric acid or the derivative thereof is preferably 0.1% by mass or more and 3% by mass or less, more preferably 0.2% by mass or more and 2% by mass or less, and more preferably 0.3% by mass or more based on the total mass of the chemical mechanical polishing aqueous dispersion. 1% by mass or less.

1.6. Preparation of Chemical Mechanical Grinding Water Dispersion

The chemical mechanical polishing aqueous dispersion of the present embodiment can be prepared by dissolving or dispersing the above components in a solvent such as water. The method of dissolving or dispersing is not particularly limited as long as it can be uniformly dissolved and dispersed. Further, the mixing order or mixing method of each component is also not particularly limited.

The chemical mechanical polishing aqueous dispersion of the present embodiment can also be prepared into a concentrated type of stock solution, and used in a solvent such as water for dilution.

2. Chemical mechanical polishing method

A chemical mechanical polishing method according to an embodiment of the present invention is characterized in that the surface to be polished having a tantalum oxide film is polished using the chemical mechanical polishing aqueous dispersion. In the following, an example of the chemical mechanical polishing method of the present embodiment (the flattening of the element isolation trench is buried) will be described with reference to the drawings.

Fig. 1 shows a target object 100 which can be used in the chemical mechanical polishing method of the present embodiment. First, a tantalum nitride film 12 as a stopper film is formed on the tantalum substrate 10 by CVD. Next, after the trench 14 is formed by RIE or the like, the tantalum oxide film 16 is deposited thereon by CVD. In this way, the object to be processed 100 is obtained.

In the tantalum oxide film 16 of Fig. 1, the tantalum oxide film 14 other than SiO ₂ buried in the trench 14 is removed by CMP using the above-described chemical mechanical polishing aqueous dispersion. In this case, the tantalum nitride film 12 serves as a stopper film, and the polishing can be stopped on the surface of the tantalum nitride film 14. Accordingly, as shown in FIG. 2, the components of the apparatus can be separated by SiO ₂ .

For the above chemical mechanical polishing, for example, the chemical mechanical polishing apparatus 200 shown in Fig. 3 can be used. FIG. 3 is a perspective view schematically showing the chemical mechanical polishing apparatus 200. The slurry 44 is supplied from the slurry supply nozzle 42 and the semiconductor substrate is held while rotating the turntable 48 to which the polishing cloth 46 is attached. The carrier head 52 of the board 50 is abutted. Moreover, FIG. 3 also shows the water supply nozzle 54 and the dresser 56.

The grinding load of the carrier head 52 can be selected within the range of 10 to 1000 hPa, preferably 30 to 500 hPa. Further, the number of revolutions of the turntable 48 and the carrier head 52 can be appropriately selected within the range of 10 to 400 rpm, preferably 30 to 150 rpm. The flow rate of the slurry 44 supplied from the slurry supply nozzle 42 can be selected within the range of 10 to 1,000 cm ³ /min, preferably 50 to 400 cm ³ /min.

A commercially available chemical mechanical polishing apparatus can be used for the grinding step. Commercially available chemical mechanical polishing apparatuses are listed, for example, "EPO-112" and "EPO-222" manufactured by Ebara Seisakusho Co., Ltd.; "LGP-510" and "LGP-552" manufactured by LAPMASTER SFT; APPLIED MATERIAL The company model "Mirra"; G&P TECHNOLOGY company model "POLI-400L".

In the chemical mechanical polishing method of the present embodiment, since the chemical mechanical polishing aqueous dispersion capable of high-speed polishing of the tantalum oxide film is used, the planar separation trench is immersed in the above-described example, or the tantalum oxide film is used as the interlayer insulating film. Flattening is especially useful.

3. Example

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited by the examples. The "parts" and "%" in the examples and comparative examples are quality standards unless otherwise specified.

3.1. Modulation of aqueous dispersions containing cerium oxide particles 3.1.1. Synthesis Example 1 (Preparation of aqueous dispersion containing chain spheroidal cerium oxide particles)

228 g of tetramethyl orthosilicate (TMOS) was weighed in an Erlenmeyer flask (capacity: 3 L), and 2,772 g of pure water was added while stirring at normal temperature. The reaction solution which was initially opaque became a transparent homogeneous solution by hydrolysis after 5 minutes. The reaction was continued for 1 hour, and a TMOS hydrolyzate of 3% by weight of a cerium oxide component was prepared. The hydrolyzate has a pH of about 4.4 because it exhibits acidity due to the sterol group formed by hydrolysis.

Add 2000g of pure water and 1N-TMAH (hydrogen hydride) to a 4-necked flask (5 liters) filled with a thermometer and a reflow head (filled with 5mm glass Raschig ring, filling height 30cm), feed tube and mixer 2 g of methylammonium) is used as a mother liquor. The pH of the mother liquor was 10.70. It is heated and the feed of the TMOS hydrolyzate is started after the reflux state. The addition rate was 16 mL/min (14.2 g ceria/hour/kg mother liquor).

After the pH was lowered to 6.35, 1N-TMAH was slowly added, and the pH was adjusted to about pH 8. Thereafter, the 1N-TMAH aqueous solution was appropriately added while maintaining the method, and the hydrolyzate was continuously added. The hydrolyzate was prepared 20 times in total every 3 hours.

After the completion of the growth of the particles, the mixture was coarsely filtered through a 90 μm sieve filter, replaced with water, concentrated by heating, and concentrated to a solid content of 20%. In this manner, an aqueous dispersion containing chain spheroidal ceria particles was prepared. The obtained cerium oxide particles were observed by SEM, and it was confirmed that the particles of three or more particles were combined into one or a plurality of columns, and it was confirmed that the particles were spheroidal cerium oxide particles.

Pour 324g of pure water into a 500mL Erlenmeyer flask and stir While stirring with a mixer, 0.067 g of 3-aminopropyltrimethoxydecane was slowly added dropwise, and stirring was continued for 1 hour. 50 g of an aqueous dispersion containing 20% of the above-mentioned chain-shaped cerium oxide particles was placed in the liquid and left for 24 hours to obtain an aqueous dispersion of cerium oxide particles.

After measuring the zeta potential and the average particle diameter, the zeta potential and the average particle diameter were measured using a zeta potential ‧ particle size measuring system (manufactured by Otsuka Electronics Co., Ltd., model "ELSZ-1000ZS"). The zeta potential at pH 3.0 was +11.7 mV and the average particle diameter was 31.5 nm.

3.1.2. Synthesis Example 2 (Preparation of aqueous dispersion containing chain spheroidal cerium oxide particles)

The same procedure as in Synthesis Example 1 was carried out except that the amount of the 3-aminopropyltrimethoxydecane used was changed to 0.049 g, and the spheroidal cerium oxide particles were synthesized. The zeta potential and the average particle diameter were measured for a sample obtained by taking out a part of the aqueous dispersion and diluted with ion-exchanged water, and the zeta potential at pH 4.8 was +5.0 mV, and the average particle diameter was 31.5 nm.

3.1.3. Synthesis Example 3 (Modulation of aqueous dispersion containing chain spheroidal cerium oxide particles)

The same procedure as in Synthesis Example 1 was carried out except that the number of times of preparation of the hydrolyzate was changed to 50 times, and the spheroidal cerium oxide particles were synthesized. The zeta potential and the average particle diameter were measured for a sample obtained by taking out a part of the aqueous dispersion and diluted with ion-exchanged water, and then the zeta potential at pH 3.0 was +11.3 mV, and the average particle diameter was 90.5 nm.

3.1.4. Synthesis Example 4 (Preparation of aqueous dispersion containing attapulgite particles)

8.0 g of tetramethyl orthosilicate (TMOS) was weighed in an Erlenmeyer flask (capacity: 3 L), and 2,535 g of pure water was added while stirring at normal temperature. The opaque reaction solution initially became a transparent homogeneous solution after 5 minutes of hydrolysis. The reaction was continued for 1 hour, and a TMOS hydrolyzate of 3% by weight of a cerium oxide component was prepared.

To a three-necked flask (5 liters) equipped with a thermometer, a reflux tube, a feed tube, and a stirrer, 2000 g of pure water and 87.7 g of triethanolamine were added to prepare a mother liquid. After heating and 70 ° C, the feed of the TMOS hydrolyzate was started. The addition rate was 19 mL/min (17 g ceria/hour/kg mother liquor).

The TMOS hydrolyzate was added dropwise for 3 hours, and the temperature was maintained at 70 ° C for 3 hours. Subsequently, the temperature was raised to 90 ° C, the addition rate was increased, and the entire amount of the TMOS hydrolyzate was added dropwise over 4 hours, and the temperature was maintained at 90 ° C for 3 hours.

After completion of the growth of the particles, the mixture was coarsely filtered with a 90 μm sieve filter, replaced with water, concentrated by heating, and concentrated to a solid content of 20% to prepare an aqueous dispersion containing attapulgite particles. The obtained cerium oxide particles were observed by SEM, and the particles having irregularities on the surface were observed, and the cerium oxide particles having irregularities were confirmed.

324 g of pure water was fed into a 500 mL Erlenmeyer flask, and while stirring with a stirrer, 0.060 g of 3-aminopropyltrimethoxydecane was slowly added dropwise, and stirring was continued for 1 hour. 50 g of an aqueous dispersion containing 20% of the above-mentioned uneven cerium oxide particles was placed in the liquid and left for 24 hours to obtain an aqueous dispersion of cerium oxide particles. For taking out the water The zeta potential and the average particle diameter were measured in a part of the dispersion and diluted with ion-exchanged water, and the zeta potential at pH 2.4 was +7.2 mV, and the average particle diameter was 46.4 nm.

3.1.5. Synthesis Example 5 (Preparation of aqueous dispersion containing attapulgite particles)

Except that the amount of 3-aminopropyltrimethoxydecane used was 0.049 g, the same operation as in Synthesis Example 4 was carried out to synthesize irregular cerium oxide particles. The zeta potential and the average particle diameter were measured for a sample obtained by taking out a part of the aqueous dispersion and diluted with ion-exchanged water, and the zeta potential at pH 3.8 was +5.1 mV, and the average particle diameter was 46.4 nm.

3.1.6. Synthesis Example 6 (Preparation of aqueous dispersion containing attapulgite particles)

Except that the amount of TMOS was changed to 3.0 g, the same operation as in Synthesis Example 4 was carried out to synthesize irregular cerium oxide particles. The zeta potential and the average particle diameter were measured for a sample obtained by taking out a part of the aqueous dispersion and diluted with ion-exchanged water, and then the zeta potential at pH 2.4 was +5.0 mV, and the average particle diameter was 30.0 nm.

3.1.7. Synthesis Example 7 (Preparation of aqueous dispersion containing attapulgite particles)

Except that the amount of TMOS was changed to 20.0 g, the same operation as in Synthesis Example 4 was carried out to synthesize irregular cerium oxide particles. The zeta potential and the average particle diameter were measured for a sample obtained by taking out a part of the aqueous dispersion and diluted with ion-exchanged water, and then the zeta potential at pH 2.4 was +7.0 mV, and the average particle diameter was 112.0 nm.

3.1.8. Synthesis Example 8 (Preparation of aqueous dispersion containing attapulgite particles)

Except that the heating and concentrating step was omitted, the same operation as in Synthesis Example 4 was carried out to synthesize irregular cerium oxide particles. The zeta potential and the average particle diameter were measured for a sample obtained by taking out a part of the aqueous dispersion and diluted with ion-exchanged water, and then the zeta potential at pH 2.4 was -0.3 mV, and the average particle diameter was 51.0 nm.

3.2. Preparation of chemical mechanical polishing water dispersion

50 parts by mass of ion-exchanged water and 3 parts by mass of the aqueous dispersion of the spheroidal cerium oxide particles obtained in the above Synthesis Example 1 in terms of cerium oxide, and finally, the total amount of all the components is 100 parts by mass. Phosphoric acid and ion-exchanged water were added so as to have a specific pH as shown in Table 1, and then filtered through a filter having a pore size of 1 μm to obtain a chemical mechanical polishing aqueous dispersion A.

In addition to the addition of the abrasive grain type shown in Table 1, in place of the spheroidal colloidal cerium oxide obtained in the above Synthesis Example 1, and the addition amount of phosphoric acid was appropriately adjusted to be the pH shown in Table 1, the remainder was dispersed with the above-mentioned chemical mechanical polishing water. The preparation method of the body A was the same, and the chemical mechanical polishing aqueous dispersions B to R were prepared. Further, the specific shape of the type of the abrasive grains to be used, or the measurement of the zeta potential and the average particle diameter are the same as those described in the above "3.1.1. Synthesis Example 1".

3.3. Evaluation method 3.3.1. Evaluation of blank wafers

A polishing pad made of a porous polyurethane (manufactured by NITTA HAAS Co., Ltd., model "IC1000XYP") was attached to a chemical mechanical polishing device (manufactured by G&P TECHNOLOGY, model "POLI-400L"), and chemical mechanical polishing was performed. In the water-based dispersions A to R, a PTEOS substrate of 4 cm × 4 cm was used as the object to be polished, and chemical mechanical polishing treatment was carried out for 2 minutes under the following polishing conditions, and the polishing rate was evaluated by the following method. The results are shown in Table 1.

<grinding conditions>

‧ Grinding device: G&P TECHNOLOGY, model "POLI-400L"

‧ polishing pad: manufactured by NITTA HAAS, "IC1000XYP"

‧Chemical mechanical grinding water dispersion rate: 100mL / min

‧ Platen revolutions: 90rpm

‧ polishing pad rotation: 90rpm

‧ polishing pad pressing pressure: 2psi

<Evaluation of grinding speed>

The film thickness before polishing was measured by a light interference type film thickness meter "NanoSpec 6100" (manufactured by Nanometrics Co., Ltd.) in the PTEOS substrate of 4 cm × 4 cm of the object to be polished. Next, the film thickness of the object to be polished which was polished for 2 minutes under the above conditions was measured using the same optical interference film thickness meter, and the difference in film thickness between the polishing and the polishing was determined, that is, it was reduced by chemical mechanical polishing. Film thickness. Next, the polishing rate was calculated from the film thickness and the polishing time which were reduced by chemical mechanical polishing. The evaluation criteria are as follows, and the polishing rate is shown in Table 1 together with the evaluation results.

‧High-speed grinding "○" when the polishing rate of the PTEOS substrate is 800 Å/min or more

‧It is not high-speed grinding "×" when the polishing speed of PTEOS substrate is less than 800Å/min

3.4. Evaluation results

The compositions and evaluation results of the chemical mechanical polishing aqueous dispersions used in Examples 1 to 7 and Comparative Examples 1 to 11 are shown in Table 1 below and Table 2 below.

Moreover, the following types of the abrasive grain types in Table 1 and Table 2 were used, respectively.

‧ST-PS-S: trade name, manufactured by Nissan Chemical Industry Co., Ltd., chain ball

‧NIPSIL E-220A: trade name, made by TOSOH SILICA Co., Ltd., chain ball

‧ST-AK-N: trade name, manufactured by Nissan Chemical Industry Co., Ltd., spherical, surface aluminum modification

‧Ludox(R)CL: trade name, made by GRACE, spherical, surface aluminum finish

‧PL-3: trade name, made by Fuso Chemical Industry Co., Ltd.

‧SEAHOSTAR KE-W10: trade name, made by Nippon Shokubai Co., Ltd., spherical

‧ST-PS-S-AK: trade name, manufactured by Nissan Chemical Industry Co., Ltd., chain-shaped, surface aluminum modified

‧ST-PS-M: trade name, manufactured by Nissan Chemical Industry Co., Ltd., chain ball

‧PL-3-CATION: trade name, made by Fuso Chemical Industry Co., Ltd., combined with spherical, surface amine modification

‧ST-AK-L: trade name, manufactured by Nissan Chemical Industry Co., Ltd., spherical, surface aluminum modification

As can be seen from the above Table 1, when the chemical mechanical polishing aqueous dispersions of Examples 1 to 7 were used, it was judged that the polishing was performed in any of the PTEOS films. High speed grinding can be achieved. On the other hand, as can be seen from the above Table 2, the chemical mechanical polishing aqueous dispersion containing the cerium oxide particles which do not satisfy the conditions of the specific cerium oxide particles of Comparative Examples 1 to 11 is judged in the polishing of any PTEOS film. It cannot be called the high speed grinding speed. As described above, when the chemical mechanical polishing aqueous dispersion of the present invention is used, the polishing rate of the tantalum oxide film is about 2 times or more as compared with the case of using the chemical mechanical polishing aqueous dispersion of Comparative Examples 1 to 11. Grinding speed.

The present invention is not limited to the above embodiments, and various changes can be made. The present invention includes substantially the same configurations as those described in the embodiments (for example, configurations having the same functions, methods, and results, or configurations having the same objects and effects). Further, the present invention includes a configuration in which the non-essential portion of the configuration described in the above embodiment is replaced with another configuration. Further, the present invention includes a configuration that can exhibit the same operational effects as those described in the above embodiments, or a configuration that achieves the same object. Further, the present invention includes the configuration of the additional conventional technology described in the above embodiment.

Claims (5)

A chemical mechanical polishing aqueous dispersion characterized by containing cerium oxide particles satisfying the following conditions (1) to (3), and having a pH of 2 or more and 5 or less: (1) an average measured by a transmission electron microscope The zeta potential at a value of 30 nm or more, (2) pH 2 or more and 5 or less is +5 mV or more, and (3) has a chain shape formed by a plurality of bonds of cerium oxide particles as primary particles, or has a concavo-convex shape. . The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the cerium oxide particles are cerium oxide particles produced by a sol-gel method. The chemical mechanical polishing aqueous dispersion according to claim 1 or 2, which further contains an organic acid. The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 3, which is used for polishing the surface to be polished having a tantalum oxide film. A chemical mechanical polishing method characterized by using the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 4 to polish a surface to be polished having a tantalum oxide film.