JP6916192B2 - Polishing composition, polishing method using it, and manufacturing method of semiconductor substrate - Google Patents

Description

The present invention relates to a polishing composition, a polishing method using the polishing composition, and a method for manufacturing a semiconductor substrate. More specifically, the present invention relates to a polishing composition preferably used for polishing a semiconductor substrate such as a silicon wafer, a polishing method using the same, and a method for manufacturing a semiconductor substrate.

In recent years, due to the high integration brought about by the miniaturization of the LSI manufacturing process, electronic devices such as computers have achieved high performance such as miniaturization, multi-functionality, and high speed. The chemical mechanical polishing (CMP) method is used in a new microfabrication technique accompanying the high integration of LSIs. The CMP method is a technique frequently used in the LSI manufacturing process, particularly in the process of forming a multilayer wiring, flattening an interlayer insulating film, forming a metal plug, and forming an embedded wiring (damer wiring).

Precision polishing using a polishing liquid is performed on the surface of materials such as metals, metalloids, non-metals, and oxides thereof. For example, the surface of a silicon wafer used as a component of a semiconductor product is generally finished into a high-quality mirror surface through a wrapping step (coarse polishing step) and a polishing step (precision polishing step). The polishing step typically includes a pre-polishing step (pre-polishing step) and a final polishing step (final polishing step).

With respect to semiconductor substrates such as silicon wafers and other substrates, higher quality surfaces are required due to the above-mentioned technological trends of high integration. In particular, in consideration of productivity, cost, etc., it is desired to obtain a high-quality surface and reduce the total polishing time (total polishing time) required for the polishing process. As one method for that, it is beneficial if the polishing rate included in the polishing step can be improved in the polishing step.

Conventionally, a polishing composition used for polishing a silicon wafer generally contains abrasive grains and a polishing accelerator such as an alkaline compound. For example, as a polishing composition used for polishing a silicon wafer, Patent Document 1 discloses a polishing liquid composition for a silicon wafer containing water, silica particles, an alkaline compound, a water-soluble polymer compound, and polyethylene glycol. ing.

International Publication No. 2013/073025

However, when the polishing liquid composition of Patent Document 1 is used, the effect of accelerating the polishing rate is still insufficient, and there is a problem that the polishing rate that guarantees good productivity cannot be realized.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a polishing composition capable of effectively improving the polishing speed of an object to be polished.

The present inventor has conducted diligent research in order to solve the above problems. As a result, they have found that the above problems can be solved by using abrasive grains, a polishing accelerator having a nucleophile parameter of 14.5 or more and 30 or less, and a polishing composition containing water, and completed the present invention. rice field.

The nucleophilic parameter is represented by the following formula (1).

According to the present invention, there is provided a polishing composition capable of effectively improving the polishing speed of an object to be polished.

The polishing composition of the present invention contains abrasive grains, a polishing accelerator having a nucleophilic parameter of 14.5 or more and 30 or less represented by the following formula (1), and water.

According to the polishing composition of the present invention, the polishing speed of the object to be polished can be effectively improved. The mechanism by which such an effect is obtained is considered to be as follows. However, the following mechanism is only speculation, and this does not limit the scope of the present invention.

As an example, in polishing when the object to be polished is a silicon wafer, _{Si (OH) x} ^{produced by nucleophilic reaction of silicon atoms and hydroxide ions (OH −} ) and further hydrolysis by protons is produced. , It is thought that it proceeds by scraping by mechanical action of abrasive grains and ^{removing by dissolution by reaction with OH −.} From this, it is considered that the important chemical reaction in polishing the object to be polished is the nucleophilic reaction. As a result of various studies on the polishing of the object to be polished, the present inventor has found that the polishing composition containing the polishing accelerator having the nucleophile parameter represented by the above (1) in a specific range is the object to be polished. It was found that the polishing speed of the sardine was effectively improved. The polishing accelerator having a nucleophilic parameter of 14.5 or more and 30 or less represented by the above formula (1) is a compound exhibiting nucleophile, and the polishing accelerator interacts with the surface of the object to be polished. It is considered that the covalent bond distance between atoms on the surface of the object to be polished can be extended and the covalent bond can be further weakened. Therefore, it is considered that the polishing of the object to be polished is facilitated by the scraping by the mechanical action of the abrasive grains and the removal by the dissolution, and the polishing speed is improved.

Therefore, the polishing composition of the present invention using a compound having a nucleophile parameter in the range of 14.5 or more and 30 or less as a polishing accelerator can effectively improve the polishing rate of the object to be polished.

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

Further, in the present specification, unless otherwise specified, the operation and the measurement of physical properties are performed under the conditions of room temperature (20 to 25 ° C.) / relative humidity of 40 to 50% RH.

[Polishing composition]
The polishing composition of the present invention contains abrasive grains, a polishing accelerator having a nucleophilic parameter represented by the above formula (1) of 14.5 or more and 30 or less, and water. Hereinafter, the structure of the polishing composition of the present invention will be described.

<Abrasive grains>
The polishing composition of the present invention indispensably contains abrasive grains. The abrasive grains contained in the polishing composition have an action of mechanically polishing the object to be polished.

The abrasive grains used may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include particles made of metal oxides such as silica, alumina, ceria, and titania, silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles. The abrasive grains may be used alone or in combination of two or more. Further, as the abrasive grains, a commercially available product or a synthetic product may be used.

Among these abrasive grains, silica is preferable, and colloidal silica is particularly preferable.

The abrasive grains may be surface-modified. Since the value of the zeta potential of ordinary colloidal silica is close to zero under acidic conditions, the silica particles do not electrically repel each other under acidic conditions and tend to agglomerate. On the other hand, the abrasive grains surface-modified so that the zeta potential has a relatively large negative value even under acidic conditions strongly repel each other even under acidic conditions and disperse well. As a result, the storage stability of the polishing composition can be improved. Such surface-modified abrasive grains can be obtained, for example, by mixing a metal such as aluminum, titanium or zirconium or an oxide thereof with the abrasive grains and doping the surface of the abrasive grains. Further, the surface-modified abrasive grains may be colloidal silica on which an organic acid is immobilized, which is obtained by chemically bonding a functional group of an organic acid to the surface of the abrasive grains.

The lower limit of the average primary particle size of the abrasive grains is preferably 10 nm or more, more preferably 15 nm or more, and further preferably 20 nm or more. The upper limit of the average primary particle size of the abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, and further preferably 100 nm or less. Within such a range, the polishing speed of the object to be polished by the polishing composition is further improved, and the occurrence of defects on the surface of the object to be polished after polishing using the polishing composition is further suppressed. be able to. The average primary particle size of the abrasive grains is calculated based on, for example, the specific surface area of the abrasive grains measured by the BET method.

The lower limit of the average secondary particle size of the abrasive grains is preferably 15 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more. The upper limit of the average secondary particle size of the abrasive grains is preferably 300 nm or less, more preferably 260 nm or less, and further preferably 220 nm or less. Within such a range, the polishing speed of the object to be polished by the polishing composition is further improved, and the occurrence of defects on the surface of the object to be polished after polishing using the polishing composition is further suppressed. be able to. The secondary particles referred to here refer to particles formed by associating abrasive particles in the polishing composition, and the average secondary particle size of the secondary particles is measured by, for example, a dynamic light scattering method. be able to.

The lower limit of the content of abrasive grains in the polishing composition is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and preferably 0.5% by mass or more. More preferred. The upper limit of the content of abrasive grains in the polishing composition is preferably 50% by mass or less, more preferably 20% by mass or less, and further preferably 5% by mass or less. Within such a range, the polishing speed of the object to be polished can be further improved, the cost of the polishing composition can be suppressed, and the surface of the object to be polished after polishing with the polishing composition can be obtained. It is possible to further suppress the occurrence of defects.

<Water>
The polishing composition according to one embodiment of the present invention indispensably contains water as a dispersion medium (solvent) in order to disperse or dissolve each component.

The dispersion medium may be a mixed solvent of water and an organic solvent for dispersion or dissolution of each component. In this case, examples of the organic solvent used include acetone, acetonitrile, ethanol, methanol, isopropanol, glycerin, ethylene glycol, propylene glycol and the like, which are organic solvents that are mixed with water. Further, these organic solvents may be used without being mixed with water to disperse or dissolve each component, and then mixed with water. These organic solvents can be used alone or in combination of two or more.

Water preferably contains as little impurities as possible from the viewpoint of contaminating the object to be cleaned and inhibiting the action of other components. As such water, for example, water having a total content of transition metal ions of 100 ppb or less is preferable. Here, the purity of water can be increased by, for example, operations such as removal of impurity ions using an ion exchange resin, removal of foreign substances by a filter, and distillation. Specifically, as the water, for example, deionized water (ion-exchanged water), pure water, ultrapure water, distilled water and the like are preferably used.

<Abrasive accelerator>
The polishing composition of the present invention contains a polishing accelerator (hereinafter, also simply referred to as a polishing accelerator) having a nucleophilic parameter of 14.5 or more and 30 or less represented by the following formula (1).

The nucleophilic parameter is a parameter used as an index showing the strength of nucleophilicity of the compound, and is described above from the test of amine reactivity with several benzhydrylium derivatives having known electrophilicity. It is calculated by the formula (1). Further, since the polishing composition of the present invention indispensably contains water, the nucleophilic parameter in the present invention is a value in water. In the present specification, the values of the nucleophilic parameters are specifically described in the reactivity parameter database of Dr. Herbert Mayr et al. Of Ludwig-Maximimilians-Universitat Munchen (Mayr's Database of Reactivity Parameter). (URL: http: //www.cup.lmu.de/oc/mayr/reactivitydatebank2/). The values of the nucleophilic slope parameters are also described in the database.

The polishing accelerator used in the polishing composition of the present invention has a nucleophilic parameter of 14.5 or more and 30 or less. It is considered that such a polishing accelerator can extend the covalent bond distance between atoms on the surface of the object to be polished and further weaken the covalent bond by interacting with the surface of the object to be polished. Therefore, it is considered that the polishing of the object to be polished is facilitated and the polishing speed is improved by scraping by the mechanical action of the abrasive grains or removing by the above-mentioned dissolution.

When a compound having the nucleophilic parameter of 14.5 or more is used, the nucleophilic interaction becomes sufficient, the covalent bond can be sufficiently weakened, and the polishing rate can be improved. From the viewpoint of improving the polishing rate, the nucleophilic parameter is preferably 16.5 or more, more preferably 17.0 or more, further preferably 17.5 or more, and 18.2. The above is particularly preferable.

On the other hand, compounds having a nucleophilic parameter of more than 30 are difficult to obtain or handle. From the viewpoint of easy availability or handling, the nucleophilic parameter is preferably 24.0 or less, and more preferably 23.0 or less.

That is, in one embodiment of the present invention, the nucleophilic parameter is preferably 14.5 or more and 24.0 or less, more preferably 14.5 or more and 23.0 or less, and 18.2 or more. It is more preferably 23.0 or less.

The type of polishing accelerator used in the polishing composition of the present invention is not particularly limited as long as the nucleophilic parameter is 14.5 or more and 30 or less. For example, it can be a compound such as an inorganic acid, an organic acid, an amine, or an amino acid, or a salt thereof. Examples of the inorganic acid having a nucleophilic parameter of 14.5 or more and 30 or less or a salt thereof include sulfite, sodium sulfite and the like. Examples of the organic acid having a nucleophilic parameter of 14.5 or more and 30 or less include mercaptocarboxylic acid, and among the mercaptocarboxylic acids, mercaptoacetic acid is preferable. Examples of amines having a nucleophilic parameter of 14.5 or more and 30 or less include dimethylamine, monomethylhydrazine, cyclic amines such as piperidine, piperidine, and hexamethyleneimine, and among cyclic amines, in a neutral to alkaline environment. From the viewpoint of stability and adsorption to the slurry, cyclic amines having 7 to 10 ring members are preferable, and hexamethyleneimine is more preferable. Examples of amino acids having a nucleophilic parameter of 14.5 or more and 30 or less include cysteine and proline. The polishing accelerator may be used alone or in combination of two or more.

That is, in one embodiment of the present invention, the polishing accelerator used in the polishing composition of the present invention is at least one selected from the group consisting of cyclic amines having 7 to 10 ring members and mercaptocarboxylic acid.

In one embodiment, the cyclic amine is hexamethyleneimine. Hexamethyleneimine exhibits high stability in a neutral to alkaline environment, and hexamethyleneimine is less likely to be adsorbed on abrasive grains, so that each component in the polishing composition containing hexamethyleneimine is more stabilized. Therefore, the polishing rate can be maintained at a high level and constant.

In another embodiment, the mercaptocarboxylic acid is mercaptoacetic acid. Similar to the above hexamethyleneimine, mercaptoacetic acid shows high stability in a neutral to alkaline environment, and mercaptoacetic acid is difficult to be adsorbed on abrasive grains. Therefore, each component in the polishing composition containing mercaptoacetic acid. Is more stable and can keep the polishing rate constant at a high level.

The content of the polishing accelerator contained in the polishing composition is not particularly limited, but is preferably 0.1% by mass or more with respect to the entire polishing composition. From the viewpoint of more effectively improving the polishing rate, the content of the polishing accelerator is more preferably 0.3% by mass or more, and further preferably 0.5% by mass or more. The upper limit of the content of the polishing accelerator contained in the polishing composition is not particularly limited, but is preferably 5.0% by mass or less, preferably 2.0% by mass, from the viewpoint of maintaining the surface quality of the object to be polished. It is more preferably mass% or less, and further preferably 1.0 mass% or less.

The content of the polishing accelerator refers to the content of one kind of polishing accelerator when it is used alone. When two or more kinds of polishing accelerators are used in combination, it means the total content of two or more kinds of polishing accelerators.

<Others>
The polishing composition of the present invention essentially contains abrasive grains, a polishing accelerator having a nucleophilic parameter of 14.5 or more and 30 or less represented by the above formula (1), and water, but in addition to the above components. Other additives may be included. Here, the other additive is not particularly limited, and an additive normally added to the polishing composition can be used. Specific examples thereof include pH adjusters, complexing agents, metal anticorrosive agents, preservatives, fungicides, reducing agents, water-soluble polymers, organic solvents for dissolving poorly soluble organic substances, and the like.

Among the above other additives, pH adjusters, preservatives, and fungicides will be described below.

<pH adjuster>
The polishing composition of the present invention may further contain a pH adjuster. The pH can be adjusted by adding an appropriate amount of a pH adjuster. The pH adjuster used as needed to adjust the pH of the polishing composition to the desired value may be either an acid or an alkali, or an inorganic or organic compound. good. Specific examples of the acid include inorganic acids such as sulfuric acid, nitrate, boric acid, carbonic acid, hypophosphoric acid, phosphite and phosphoric acid; formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid. , N-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycol Acids, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, maleic acid, phthalic acid, malic acid, tartaric acid, carboxylic acids such as citric acid and lactic acid, and methanesulfonic acid, Examples thereof include organic acids such as organic sulfuric acids such as ethanesulfonic acid and isethionic acid. Specific examples of the alkali include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate or salts thereof, ammonia, amines, quaternary ammonium salts and the like. These pH regulators can be used alone or in admixture of two or more.

The pH of the polishing composition according to one embodiment of the present invention is preferably 7.0 or higher from the viewpoint of further improving the polishing rate of the object to be polished. The pH of the polishing composition according to the present invention is more preferably 9.0 or higher, and even more preferably 10.0 or higher. The upper limit of the pH of the polishing composition of the present invention is not particularly limited, but is preferably 12.0 or less, preferably 11.0 or less, from the viewpoint of economy and handling safety of the polishing composition. More preferably. For the pH of the polishing composition, a pH meter (for example, manufactured by Horiba Seisakusho Co., Ltd., model number: LAQUA (registered trademark)) was used, and a standard buffer solution (phthalate pH buffer solution [pH: 4.01 (25)) was used. ° C)], neutral phosphate pH buffer [pH: 6.86 (25 ° C)], carbonate pH buffer [pH: 10.01 (25 ° C)]) after three-point calibration. , The glass electrode can be obtained by putting the glass electrode in the polishing composition and measuring the value after it has stabilized after 2 minutes or more.

<Preservatives and fungicides>
Further, examples of preservatives and fungicides that can be contained in the polishing composition if necessary include 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3. Examples thereof include isothiazolinone-based preservatives such as −ON, paraoxybenzoic acid esters, and phenoxyethanol. These preservatives and fungicides may be used alone or in combination of two or more.

The polishing composition of the present invention may be a one-component type or a multi-component type including a two-component type. Further, the polishing composition of the present invention may be prepared by diluting the stock solution of the polishing composition with a diluted solution such as water, for example, 10 times or more.

[Object to be polished]
The object to be polished using the polishing composition according to one embodiment of the present invention is not particularly limited, and examples thereof include objects to be polished having various materials and shapes. The material to be polished is, for example, a silicon material, aluminum, nickel, tungsten, steel, tantalum, titanium, stainless steel or other metal or semi-metal, or an alloy thereof; quartz glass, aluminosilicate glass, glassy carbon. Glassy materials such as: Alumina, silica, sapphire, silicon nitride, tantalum nitride, titanium carbide and other ceramic materials; silicon carbide, gallium nitride, gallium arsenide and other compound semiconductor substrate materials; Can be mentioned. Further, the object to be polished may be composed of a plurality of the above materials.

Among these, since the effect of the polishing composition according to the present invention can be obtained more remarkably, it is preferable that the polishing object contains a silicon material. That is, it is preferable that the polishing composition according to one embodiment of the present invention is used for polishing an object to be polished containing a silicon material.

Further, the silicon material preferably contains at least one material selected from the group consisting of silicon single crystal, amorphous silicon and polysilicon. As the silicon material, a silicon single crystal or polysilicon is more preferable, and a silicon single crystal is particularly preferable, from the viewpoint that the effect of the present invention can be obtained more remarkably. That is, in one embodiment of the present invention, the object to be polished is preferably an object to be polished containing single crystal silicon, and more preferably a single crystal silicon substrate (silicon wafer).

Further, the shape of the object to be polished is not particularly limited. The polishing composition according to the present invention can be preferably applied to polishing an object to be polished having a flat surface such as a plate shape or a polyhedral shape.

[Manufacturing method of polishing composition]
The method for producing the polishing composition of the present invention is not particularly limited, and for example, it can be obtained by stirring and mixing abrasive grains, a polishing accelerator and, if necessary, other additives in water as a dispersion medium. can. When a pH adjuster containing a dispersion medium (water) is added, abrasive grains, a polishing accelerator and, if necessary, other additives are stirred and mixed in the pH adjuster containing the dispersion medium (water). The method may be adopted. The temperature at which the abrasive grains and each component are mixed is not particularly limited, but is preferably 10 to 40 ° C., and may be heated in order to increase the dissolution rate. Further, the mixing time is not particularly limited as long as it can be uniformly mixed.

[Polishing method and semiconductor substrate manufacturing method]
As described above, the polishing composition of the present invention is suitably used for polishing a polishing object containing single crystal silicon, particularly a single crystal silicon substrate (silicon wafer). That is, in one embodiment of the present invention, there is provided a polishing composition used for polishing an object to be polished containing single crystal silicon. In another embodiment, a polishing composition used for polishing a single crystal silicon substrate (silicon wafer) is provided.

The present invention also provides a polishing method for polishing an object to be polished containing single crystal silicon using the polishing composition of the present invention. In another embodiment, a polishing method for polishing a single crystal silicon substrate using the polishing composition of the present invention is also provided.

Furthermore, the present invention also provides a method for manufacturing a semiconductor substrate, which comprises a step of polishing an object to be polished containing single crystal silicon by the above-mentioned polishing method. In another embodiment, there is also provided a method for manufacturing a semiconductor substrate, which comprises a step of polishing the single crystal silicon substrate by the polishing method.

The polishing step in the polishing method according to the present invention is not particularly limited as long as it is a step of polishing a single crystal silicon substrate, but a chemical mechanical polishing (CMP) step is preferable. Further, the polishing step may be a polishing step including a single step or a polishing step including a plurality of steps. As a polishing step including a plurality of steps, for example, a step of performing a finish polishing step after a preliminary polishing step (coarse polishing step) and a step of performing one or more secondary polishing steps after the primary polishing step are performed. After that, a step of performing a finish polishing step and the like can be mentioned.

The polishing apparatus used in the polishing method according to the present invention is a polishing surface plate to which a holder for holding a semiconductor substrate or the like and a motor or the like whose rotation speed can be changed are attached, and a polishing pad (polishing cloth) can be attached. A general polishing device having the above can be used. As the polishing device, any of a small tabletop polishing machine, a single-sided polishing device, and a double-sided polishing device may be used.

As the polishing pad, general non-woven fabric, polyurethane, porous fluororesin and the like can be used without particular limitation. The polishing pad is preferably grooved so that the polishing liquid can be collected.

The polishing conditions are not particularly limited, and for example, the rotation speed of the polishing surface plate (platen) is preferably 10 to 500 rpm. The head (carrier) rotation speed is preferably 10 to 500 rpm. The pressure (polishing pressure) applied to the substrate having the object to be polished is preferably 0.5 to 10 psi. The method of supplying the polishing composition to the polishing pad is also not particularly limited, and for example, a method of continuously supplying the polishing composition with a pump or the like is adopted. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the polishing composition, and for example, it is preferably 10 ml / min or more and 5000 ml / min or less. The polishing time is not particularly limited, but the step using the polishing composition is preferably 5 seconds or more and 180 seconds or less.

After the polishing is completed, the substrate is washed in running water, and the water droplets adhering to the substrate are wiped off by a spin dryer or the like and dried to obtain a semiconductor substrate.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass", respectively. Further, in the following examples, unless otherwise specified, the operation was performed under the conditions of room temperature (25 ° C.) / relative humidity of 40 to 50% RH.

The average secondary particle size of the abrasive grains was measured using a dynamic light scattering type particle size / particle size distribution measuring device (model number: UPA UT-151 manufactured by Nikkiso Co., Ltd.). First, the abrasive grains were dispersed in pure water to prepare a dispersion having a loading index (laser scattering intensity) of 0.01. Next, using this dispersion, the value of the volume average particle size Mv (value of D50) in the UT mode was measured, and the obtained value was taken as the average secondary particle size.

(1) Preparation of Polishing Composition [Example 1]
(Preparation of polishing composition (A-1))
In water, colloidal silica as abrasive grains (average primary particle size 35 nm, average secondary particle size 63 nm) 0.5% by mass, sodium sulfite 0.05 mol / L as a polishing accelerator, potassium hydroxide as a pH adjuster Was added in an amount of pH 10.5 and mixed to prepare a polishing composition (A-1).

[Examples 2 to 6 and Comparative Examples 1 to 5]
(Preparation of Polishing Compositions (A-2) to (A-6) and (C-1) to (C-5))
Each polishing composition was prepared in the same manner as in Example 1 except that the type of polishing accelerator and the type of pH adjusting agent were changed as shown in Table 1 below (mixing temperature: about 25 ° C.). , Mixing time: about 10 minutes).

(Measurement of pH of polishing composition)
The pH of each polishing composition (liquid temperature: 25 ° C.) was confirmed by a pH meter (HORIBA, Ltd. model number: LAQUA (registered trademark)).

(Nucleophilic parameter of polishing accelerator)
The nucleophilic parameter of each polishing accelerator is represented by the following formula (1).

As the value of this nucleophilic parameter, the value described in the reactivity parameter database (Mayr's Database of Reactivity Parameters) of Dr. Herbert Mayr et al. Of Ludwig-Maxilians-Universitat Munchen was adopted (URL). cup.lmu.de/oc/mayr/reactivity database2 /). The values of the nucleophilic parameters of each polishing accelerator are shown in Table 1 below.

(2) Polishing Using each of the polishing compositions obtained above, an 8-inch single crystal silicon substrate was polished under the following polishing conditions.

<Polishing conditions>
Polishing device: Small tabletop polishing machine (manufactured by Nippon Engis Co., Ltd., EJ380IN)
Polishing pad: Hard polyurethane pad (Nitta Haas Co., Ltd., IC1000)
Platen (surface plate) rotation speed: 60 [rpm]
Head (carrier) rotation speed: 60 [rpm]
Polishing pressure: 3.0 [psi]
Flow rate of polishing composition (slurry): 100 [ml / min]
Polishing time: 1 [min]
(3) Measurement of polishing speed The polishing speed was measured by the following procedure.

1. 1. Using an electronic balance GH-202 (manufactured by A & D Co., Ltd.), the mass of the object to be polished (single crystal silicon substrate) before and after polishing is measured, and from these differences, the object to be polished before and after polishing is used. The amount of change in mass ΔM _Si (kg) was calculated.

2. By dividing the amount of change in mass of the object to be polished ΔM _Si (kg) before and after polishing by the specific gravity of silicon 2.33 × 10 ³ (kg / m ³ ), the amount of change in volume of the object to be polished before and after polishing ΔV _Si ( m ³ ) was calculated.

3. 3. By dividing the volume change amount ΔV _Si (m ³ ) of the polishing object _{before and after polishing by the area S Si} (m ² ) of the polishing surface of the polishing object, the thickness change amount Δd _Si (m 3) of the polishing object before and after polishing m) was calculated.

4. The amount of change in thickness of the object to be polished before and after polishing Δd _Si (m) was divided by the polishing time t (min), and the unit was further converted to (Å / min). This value was defined as the polishing rate v _Si (Å / min).

The results of polishing using each polishing composition are summarized in Table 1.

(4) Stability of polishing accelerator in alkaline environment In Table 1, regarding stability evaluation in alkaline environment, Δ indicates that cysteine, which is a polishing accelerator, is air-oxidized with a trace amount of heavy metal and alkali. Indicates that care must be taken when using in an alkaline environment as it may cause cystine.

(5) Adsorption of polishing accelerator to abrasive grains The adsorptivity of the polishing accelerator to silica (abrasive grains) was measured by the following method. Specifically, first, a polishing accelerator was added to a 1 mass% silica (abrasive grain) aqueous solution so as to have a concentration of 0.05 mol / L. Then, it was stored in an air bath at 80 ° C. to promote the adsorption reaction. After 1 week, it was taken out and cooled, and then the solid and liquid were separated by a centrifuge (1 hour at 26,000 rpm), and only the supernatant was collected. The collected supernatant was measured with a total carbon measuring device (TOC-5000A manufactured by Shimadzu Corporation) to measure the residual amount of the polishing accelerator. The results are summarized in Table 1. If the residual amount is 80% or more, it is evaluated as ◯, and if it is less than 80%, it is evaluated as Δ.

“-” In Table 1 above indicates that the measurement has not been performed.

From the results shown in Table 1 above, it was confirmed that the polishing composition according to the example had an excellent effect of improving the polishing rate as compared with the polishing composition of the comparative example.

Claims (6)

A polishing composition containing abrasive grains, a polishing accelerator having a nucleophilic parameter of 14.5 or more and 30 or less represented by the following formula (1), and water .
The polishing accelerator is a cyclic amine having 7 or more and 10 or less ring members, and is a polishing composition.

The cyclic amine is hexamethylene imine, the polishing composition according to claim 1. The polishing composition according to claim 1 or 2 , wherein the pH is 7.0 or higher. The polishing composition according to any one of claims 1 to 3 , which is used for polishing a single crystal silicon substrate. A polishing method for polishing a single crystal silicon substrate using the polishing composition according to any one of claims 1 to 4. A method for manufacturing a semiconductor substrate, which comprises a step of polishing a single crystal silicon substrate by the polishing method according to claim 5.