Composition for chemical mechanical polishing and polishing method

Abstract

To provide a composition for chemical mechanical polishing and a polishing method that can effectively suppress contamination of foreign matters during manufacturing and can polish the surface of a semiconductor substrate to a flat surface.SOLUTION: The composition for chemical mechanical polishing according to the present invention contains abrasive grains including silica and a liquid medium, wherein when the abrasive grain component containing silica is defined as x[mass%] for the content of surface silanol groups measured by the Sears method and y[mass%] for the content of bulk silanol groups measured by solid 29Si-DD / MAS-NMR, the percentage of silanol groups on the surface expressed as (x / y)×100[%] is equal to or less than 15%, and the abrasive grain component including silica has at least one functional group selected from the functional groups represented by the following general formulas (1) to (4), -SO3-M+ (1), -COO-M+ (2), -NR1R2 (3), -N+R1R2R3M- (4).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition for chemical mechanical polishing and a polishing method using the same.

Background Art

[0002] With the improvement of semiconductor manufacturing technology, higher integration and faster operation of semiconductor devices are required. Along with this, the flatness required for the surface of a semiconductor substrate in the manufacturing process of fine semiconductors in semiconductor devices has become increasingly strict, and chemical mechanical polishing (CMP) has become an indispensable technology in the manufacturing process of semiconductor devices.

[0003] CMP is utilized, for example, in planarization of an interlayer insulating film, formation of a metal plug, and formation of embedded wiring (damascene wiring) in a multilayer wiring formation process. In order to achieve well-balanced polishing characteristics in such processes, various polishing compositions (slurries) have been proposed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since such a polishing composition contains abrasive grains, it is likely to damage manufacturing equipment such as piping during the production of the polishing composition, and foreign matter derived from the manufacturing equipment may be mixed in. The mixing of such foreign matter not only impairs the flatness of the semiconductor substrate surface but also may cause polishing defects such as polishing scratches.

[0006] Some aspects of the present invention provide a chemical mechanical polishing composition and a polishing method that can effectively suppress the inclusion of foreign matter during manufacturing and can polish the surface of a semiconductor substrate flatly.

Means for Solving the Problems

[0007] One aspect of the chemical mechanical polishing composition according to the present invention is (A) abrasive grains containing silica, (B) a liquid medium, and is a chemical mechanical polishing composition containing when the content of surface silanol groups measured by the shear method of the component (A) is x [mass%] and the content of bulk silanol groups measured by solid 29 Si-DD / MAS-NMR is y [mass%], the ratio of silanol groups present on the surface represented by (x / y)×100 [%] is 15% or less, the component (A) has at least one functional group selected from the functional groups represented by the following general formulas (1) to (4). -SO3 - M + ·····(1) -COO - M + ·····(2) (In the above formulas (1) and (2), M + represents a monovalent cation.) -NR 1 R 2 ·····(3) -N + R 1 R 2 R 3 M - ·····(4) (In the above formulas (3) and (4), R 1 , R 2 , and R 3 each independently represents a hydrogen atom, or a substituted or unsubstituted hydrocarbon group. M - represents an anion.)

[0008] In one aspect of the chemical mechanical polishing composition, The component (A) may be abrasive grains containing silica particles having at least one functional group selected from the functional groups represented by the general formulas (1) to (4) fixed to the surface via a covalent bond.

[0009] In any aspect of the chemical mechanical polishing composition, Furthermore, (C) an organic acid may be contained.

[0010] In any aspect of the chemical mechanical polishing composition, The component (C) may contain at least one selected from the group consisting of acetic acid, malonic acid, citric acid, maleic acid, and tartaric acid.

[0011] In any aspect of the chemical mechanical polishing composition, The pH may be 1 or more and 7 or less.

[0012] In any aspect of the chemical mechanical polishing composition, The content of the component (A) may be 0.1% by mass or more and 20% by mass or less with respect to 100% by mass of the chemical mechanical polishing composition.

[0013] One aspect of the polishing method according to the present invention includes a step of polishing a semiconductor substrate using the chemical mechanical polishing composition of any of the above aspects.

[0014] In one aspect of the polishing method, The semiconductor substrate may include a portion containing a silicon oxide film and a silicon nitride film.

Effects of the Invention

[0015] According to the chemical mechanical polishing composition of the present invention, the incorporation of foreign matter during the production of the composition can be effectively suppressed, and the surface of the semiconductor substrate can be polished flat.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and also includes various modified examples implemented without changing the gist of the present invention.

[0018] In this specification, the numerical range described using "X to Y" means that the numerical value X is included as the lower limit value and the numerical value Y is included as the upper limit value.

[0019] 1. Composition for Chemical Mechanical Polishing The composition for chemical mechanical polishing according to an embodiment of the present invention contains (A) abrasive grains containing silica (also referred to as "(A) component" in this specification) and (B) a liquid medium (also referred to as "(B) component" in this specification), and the content of surface silanol groups measured by the shear method in the (A) component is x [mass%], and the bulk silanol group content measured by Si-DD / MAS-NMR is When it is y [mass%], the ratio of silanol groups present on the surface represented by (x / y)×100 [%] is 15% or less, and it has at least one functional group selected from the functional groups represented by the following general formulas (1) to (4). Hereinafter, the components that can be included in the composition for chemical mechanical polishing according to this embodiment will be described in detail. 29 When the content of bulk silanol groups measured by Si-DD / MAS-NMR is y [mass%], the ratio of silanol groups present on the surface represented by (x / y)×100 [%] is 15% or less, and it has at least one functional group selected from the functional groups represented by the following general formulas (1) to (4). Hereinafter, the components that can be included in the composition for chemical mechanical polishing according to this embodiment will be described in detail.

[0020] 1.1. (A) Abrasive Grains Containing Silica The chemical mechanical polishing composition according to this embodiment contains abrasive grains containing (A) silica. The content of surface silanol groups in component (A) measured by the Sears method is x [mass%], and the solid 29 When the content of bulk silanol groups measured by Si-DD / MAS-NMR is y [mass%], the ratio of silanol groups present on the surface represented by (x / y)×100 [%] is 15% or less. When the ratio of silanol groups present on the surface of component (A) is 15% or less, the formation of ring structures is promoted while sharing the oxygen of SiO4 tetrahedrons, the ring size becomes larger and the strain becomes smaller, and component (A) becomes less likely to undergo elastic deformation. Therefore, it has excellent mechanical strength and good polishing characteristics of the chemical mechanical polishing composition.

[0021] The content of surface silanol groups in component (A) is the value measured by the Sears method. Specifically, it is measured under the conditions shown below. Collect a silica sol corresponding to 1.5 g of silica particles, add pure water to make the liquid volume 90 mL. In an environment at 25 °C, add a 0.1 mol / L hydrochloric acid aqueous solution until the pH reaches 3.6, add 30 g of sodium chloride, and gradually add pure water while completely dissolving the sodium chloride. Finally, add pure water until the total volume of the test solution reaches 150 mL to obtain a test solution. Put the obtained test solution into an automatic titrator, drop a 0.1 mol / L sodium hydroxide aqueous solution, and measure the titration volume A (mL) of the 0.1 mol / L sodium hydroxide aqueous solution required for the pH to change from 4.0 to 9.0. Using the following formula (a), calculate the consumption volume V (mL) of the 0.1 mol / L sodium hydroxide aqueous solution required for the pH of 1.5 g of silica particles to change from 4.0 to 9.0, and use the following formula (b) to calculate the content x (mass%) of surface silanol groups of the silica particles. V=(A×f×100×1.5) / (W×C) (a) A: Titration volume (mL) of the 0.1 mol / L sodium hydroxide aqueous solution required for the pH of 1.5 g of silica particles to change from 4.0 to 9.0 f: Normality of the 0.1 mol / L sodium hydroxide aqueous solution used C: Concentration of silica particles in silica sol (mass%) W: Sampling amount of silica sol (g) x = (B × 17 / M) × 100 (b) B: Amount of sodium hydroxide (mol) required for the pH per 1.5 g of silica particles calculated from V to be from 4.0 to 9.0 M: Amount of silica particles (1.5 g)

[0022] Note that the method for measuring and calculating the surface silanol group density of component (A) referred to "G.W. Sears, Jr., Analytical Chemistry, Vol. 28, No. 12, pp. 1981 - 1983 (1956).", "Japanese Patent Publication No. 5967118", and "Japanese Patent Publication No. 6047395".

[0023] (A) The content of the surface silanol groups of the component is preferably 0.01 mass% or more, more preferably 0.05 mass% or more. (A) The content of the surface silanol groups of the component is preferably 1.4 mass% or less, more preferably 1.0 mass% or less. (A) component When the content of the surface silanol groups of component (A) is 0.01 mass% or more, component (A) has appropriate surface repulsion and excellent dispersion stability. Also, when the content of the surface silanol groups of component (A) is 1.4 mass% or less, component (A) has appropriate surface repulsion and can exhibit a sufficient polishing rate while suppressing the aggregation of component (A).

[0024] (A) The content of the bulk silanol groups of the component is the value measured by solid 29 Si - DD / MAS - NMR. Specifically, it is measured under the conditions shown below. The silica sol containing component (A) is freeze - dried to obtain a measurement sample. Using a 400 MHz nuclear magnetic resonance apparatus, a CP / MAS probe with a diameter of 7.5 mm is attached, and the observed nucleus is 29 Si, and measured by the DD / MAS method. The measurement conditions are 29 The Si resonance frequency is 79.43 MHz, 29 The Si 90° pulse width is 5 μs, 1The resonance frequency of H is 399.84 MHz, 1 the decoupling frequency of H is 50 kHz, the MAS rotation speed is 4 kHz, the spectral width is 30.49 kHz, and the measurement temperature is 23 °C. For data analysis, for each peak in the spectrum after Fourier transform, the center position, height, and half-width of the peak shape created by the mixture of Lorentz waveform and Gaussian waveform are used as variable parameters, and optimization calculation is performed by the non-linear least squares method. For the four structural units Q1, Q2, Q3, and Q4, from the obtained content ratio of Q1, content ratio of Q2, content ratio of Q3, and content ratio of Q4, the content ratio y (mass%) of the bulk silanol group is calculated using the following formula (c). y = {(content ratio of Q3 × 17 + content ratio of Q2 × 17 × 2 + content ratio of Q1 × 17 × 3) / (60 + content ratio of Q3 × 1 + content ratio of Q2 × 2 + content ratio of Q1 × 3)} × 10 (c)

[0025] In this embodiment, the content ratio of the bulk silanol group of the component (A) is measured by the DD / MAS method (Dipolar Decoupling / Magic Angle Spinning), rather than the CP / MAS method (Cross Polarization / Magic Angle Spinning). On the other hand, since the DD / MAS method has no sensitization effect like the CP / MAS method, the obtained peak accurately reflects the content ratios of Q1, Q2, Q3, and Q4, and is suitable for quantitative analysis.

[0026] The structural units are classified into Q1 to Q4 according to the degree of connection of SiO4 tetrahedrons, and are as follows respectively. · Q1 is a structural unit having one Si around Si via oxygen. The SiO4 tetrahedron is connected to another SiO4 tetrahedron, and the solid 29 has a peak at around -80 ppm in the Si-DD / MAS-NMR spectrum. · Q2 is a structural unit having two Si around Si via oxygen. The SiO4 tetrahedron is connected to another two SiO4 tetrahedrons, and the solid 29It has a peak around -91 ppm in the Si-DD / MAS-NMR spectrum. ·Q3 is a structural unit having three Si atoms around Si through oxygen. The SiO4 tetrahedron is connected to three other SiO4 tetrahedrons, and the solid 29 It has a peak around -101 ppm in the Si-DD / MAS-NMR spectrum. ·Q4 is a structural unit having four Si atoms around Si through oxygen. The SiO4 tetrahedron is connected to four other SiO4 tetrahedrons, and the solid 29 It has a peak around -110 ppm in the Si-DD / MAS-NMR spectrum.

[0027] (A) The content of the bulk silanol groups in the component is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. (A) The content of the bulk silanol groups in the component is preferably 8.0% by mass or less, more preferably 7.5% by mass or less. When the content of the bulk silanol groups in the (A) component is 0.1% by mass or more, the production of silica particles can be easily carried out. Further, when the content of the bulk silanol groups in the (A) component is 8% by mass or less, the formation of the ring is promoted while sharing the oxygen of the SiO4 tetrahedron, and the ring size becomes large and there are few defects, the mechanical strength of the (A) component is excellent, and the polishing characteristics of the chemical mechanical polishing composition are good.

[0028] (A) When the ratio of the silanol groups present on the surface of the component is x mass% for the content of the surface silanol groups measured by the shear method and y mass% for the content of the bulk silanol groups measured by Si-DD / MAS-NMR, it is represented by (x / y)×100 [%]. 29 Si-DD / MAS-NMR measures the content of the bulk silanol groups as y mass%.

[0029] (A) Since the ratio of the silanol groups present on the surface of the component can facilitate the production of the (A) component, it is preferably 1% or more, more preferably 2% or more.

[0030] The proportion of silanol groups present on the surface of the component (A) is 15% or less, preferably 10% or less, because while maintaining the amorphous structure, the formation of member rings is promoted while sharing the oxygen of SiO4 tetrahedrons, resulting in few defects in the silica particles, excellent mechanical strength, and good polishing characteristics of the chemical mechanical polishing composition.

[0031] The proportion of silanol groups present on the surface of the component (A) can be set within a desired range by adjusting the conditions of the hydrolysis reaction and condensation reaction of alkoxysilane and the conditions of subsequent treatment. Specifically, methods include subjecting the silica sol obtained by the hydrolysis reaction and condensation reaction of alkoxysilane to a pressure-heat treatment; performing the hydrolysis reaction and condensation reaction separately; adding a reaction accelerator in the hydrolysis reaction and condensation reaction, etc. Among these methods, since it is easy to control the content rate of the surface silanol groups of the component (A) and the content rate of the bulk silanol groups of the component (A), and it is possible to precisely control the proportion of silanol groups present on the surface of the component (A), the method of subjecting the silica sol obtained by the hydrolysis reaction and condensation reaction of alkoxysilane to a pressure-heat treatment is preferred.

[0032] The component (A) is an abrasive grain mainly composed of silica, but may contain other components. Examples of other components include aluminum compounds and silicon compounds. When the component (A) further contains an aluminum compound or a silicon compound, the surface hardness of the component (A) can be reduced, so that the damage to manufacturing equipment such as pipes during manufacturing can be reduced, and the mixing of foreign matters during manufacturing can be suppressed in some cases. Also, in some cases, the occurrence of polishing scratches and dishing on the polished surface of a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be further reduced.

[0033] Examples of the aluminum compound include aluminum hydroxide, aluminum oxide (alumina), aluminum chloride, aluminum nitride, aluminum acetate, aluminum phosphate, aluminum sulfate, sodium aluminate, potassium aluminate, and the like. On the other hand, examples of the silicon compound include silicon nitride, silicon carbide, silicate, silicone, and silicon resin.

[0034] (A) The average particle diameter of the component is preferably 10 nm or more and 300 nm or less, more preferably 20 nm or more and 200 nm or less. When the average particle diameter of the (A) component is within the above range, a sufficient polishing rate can be obtained, and a chemically mechanical polishing composition excellent in stability that does not cause sedimentation and separation of particles may be obtained. The average particle diameter of the (A) component can be obtained, for example, by measuring the specific surface area by the BET method using a dynamic adsorption surface area automatic measuring device (manufactured by Micromeritics, "Micromeritics FlowSorb II 2300") and calculating from the measured value.

[0035] (A) When the total mass of the chemically mechanical polishing composition is 100% by mass, the content of the component is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more. (A) When the total mass of the chemically mechanical polishing composition is 100% by mass, the content of the component is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less. When the content of the (A) component is within the above range, dishing of a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be more effectively suppressed in some cases.

[0036] Further, the (A) component has at least one functional group selected from the functional groups represented by the following general formulas (1) to (4) on at least a part of its surface. -SO3 - M + ·····(1) -COO - M + ·····(2) (In the above formulas (1) and (2), M + represents a monovalent cation.) -NR 1 R 2 ·····(3) -N + R 1 R 2 R 3 M - ·····(4) (In the above formulas (3) and (4), R 1 , R 2 , and R 3 each independently represent a hydrogen atom, or a substituted or unsubstituted hydrocarbon group. M - represents an anion.)

[0037] (When at least a part of the surface of the abrasive grains of component (A) is modified with at least one functional group selected from the functional groups represented by the above general formulas (1) to (4), particularly in the range where the pH is 1 or more and 7 or less, the absolute value of the zeta potential becomes larger than that of the abrasive grains not surface-modified with the functional group, and the electrostatic repulsive force between the abrasive grains increases. As a result, the dispersion stability of the abrasive grains in the chemical mechanical polishing composition is improved, so that polishing can be performed while reducing the occurrence of polishing scratches and dishing. In addition, adhesion of the abrasive grains to the manufacturing equipment piping during the production of the chemical mechanical polishing composition can be suppressed, and damage to the manufacturing equipment piping caused by the abrasive grains can be suppressed. Thereby, contamination by foreign matters during production can be effectively suppressed, and a chemical mechanical polishing composition having stable polishing characteristics can be produced.)

[0038] Furthermore, silica particles tend to react with water, oxygen, nitrogen, etc. and tend to deteriorate over time. However, when component (A) is abrasive grains in which at least a part of the surface is modified with at least one functional group selected from the functional groups represented by the above general formulas (1) to (4), there are cases where the functional group can reduce the reactivity of water, oxygen, nitrogen, etc. on the abrasive grain surface and suppress deterioration.)

[0039] <Component (A) having a functional group represented by the general formula (1)> The component (A) may have a functional group represented by the following general formula (1) on at least a portion of its surface. -SO3 - M + ...(1) (M + represents a monovalent cation.)

[0040] In the above formula (1), M + Examples of monovalent cations represented by the formula (I) include, but are not limited to, H + , Li + , Na + , K + , NH4 + In other words, the functional group represented by the above general formula (1) can be rephrased as "at least one functional group selected from the group consisting of sulfo groups and salts thereof." Here, the "salt of a sulfo group" refers to a functional group that converts a hydrogen ion contained in a sulfo group (-SO3H) into Li + , Na + , K + , NH4 + Here, "component (A) having a functional group represented by general formula (1)" refers to a component having a functional group represented by general formula (1) fixed to its surface via a covalent bond, and does not include a component having a compound having a functional group represented by general formula (1) physically or ionically adsorbed to its surface.

[0041] The component (A) having a functional group represented by the general formula (1) can be produced, for example, by applying the method described in JP-A-2010-269985. The mercapto group-containing silane coupling agent is thoroughly stirred in an acidic medium to covalently bond the mercapto group-containing silane coupling agent to the surface of the silica. Examples of the mercapto group-containing silane coupling agent include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. Next, an appropriate amount of hydrogen peroxide is further added and the mixture is left to stand for a sufficient period to obtain component (A) having a functional group represented by general formula (1).

[0042] The zeta potential of the component (A) having a functional group represented by the general formula (1) is a negative potential in the chemical mechanical polishing composition, and the negative potential is preferably -10 mV or less, more preferably -20 mV or less. When the zeta potential of the component (A) having a functional group represented by the general formula (1) is within the above range, the electrostatic repulsive force between the components (A) effectively prevents aggregation of particles, and in some cases, a substrate having a positive charge during chemical mechanical polishing can be selectively polished. Examples of the zeta potential measuring device include "ELSZ-1" manufactured by Otsuka Electronics Co., Ltd., "Zetasizer nano zs" manufactured by Malvern, etc. The zeta potential of the component (A) having a functional group represented by the general formula (1) can be adjusted by appropriately increasing or decreasing the addition amount of the mercapto group-containing silane coupling agent or the like described above.

[0043] When the chemical mechanical polishing composition according to the present embodiment contains the component (A) having a functional group represented by the general formula (1), the content of the component (A) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more when the total mass of the chemical mechanical polishing composition is 100% by mass. The content of the component (A) is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less when the total mass of the chemical mechanical polishing composition is 100% by mass. When the content of the component (A) having a functional group represented by the general formula (1) is within the above range, dishing of a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be more effectively suppressed, and the storage stability of the chemical mechanical polishing composition may be improved.

[0044] <The component (A) having a functional group represented by the general formula (2)> (A) component may have a functional group represented by the following general formula (2) on at least a part of its surface. -COO - M + ·····(2) (M + represents a monovalent cation.)

[0045] In the above formula (2), M + Examples of the monovalent cation represented by include, but are not limited to, for example, H + , Li + , Na + , K + , NH4 + . That is, the functional group represented by the above general formula (2) can also be paraphrased as "at least one functional group selected from the group consisting of a carboxy group and its salts". Here, the "salt of a carboxy group" refers to a functional group in which the hydrogen ion contained in the carboxy group (-COOH) is replaced with a monovalent cation such as Li + , Na + , K + , NH4 + , etc. Here, the "(A) component having a functional group represented by the general formula (2)" refers to one in which the functional group represented by the general formula (2) is covalently fixed on its surface, and does not include those in which a compound having a functional group represented by the general formula (2) is physically or ionically adsorbed on its surface.

[0046] The (A) component having a functional group represented by the general formula (2) can be produced, for example, by applying the method described in JP-A-2010-105896. Specifically, silica and a silane coupling agent containing a carboxylic anhydride are sufficiently stirred in a basic medium composed of water, methanol, and ammonia to covalently bond the carboxylic anhydride silane coupling agent to the surface of the silica, and further hydrolyze the modified carboxylic anhydride to undergo a ring-opening reaction to a dicarboxylic acid, whereby the (A) component having a functional group represented by the general formula (2) can be obtained. Here, examples of the silane coupling agent containing a carboxylic anhydride include for example, 3-(triethoxysilyl)propyl succinic anhydride and the like.

[0047] The zeta potential of the component (A) having a functional group represented by the general formula (2) is a negative potential in the chemical mechanical polishing composition, and the negative potential is preferably -10 mV or less, more preferably -12 mV or less. When the zeta potential of the component (A) having a functional group represented by the general formula (2) is within the above range, the electrostatic repulsive force between abrasive grains can effectively prevent aggregation of particles, and there is a case where a substrate having a positive charge during chemical mechanical polishing can be selectively polished. Note that, as the zeta potential measuring device, the above-described device can be used. The zeta potential of the component (A) having a functional group represented by the general formula (2) can be adjusted by appropriately increasing or decreasing the addition amount of the above-described carboxylic anhydride-containing silane coupling agent or the like.

[0048] When the chemical mechanical polishing composition according to the present embodiment contains the component (A) having a functional group represented by the general formula (2), the content of the component (A) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more when the total mass of the chemical mechanical polishing composition is 100% by mass. The content of the component (A) is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less when the total mass of the chemical mechanical polishing composition is 100% by mass. When the content of the component (A) having a functional group represented by the general formula (2) is within the above range, dishing of a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be more effectively suppressed, and the storage stability of the chemical mechanical polishing composition may be improved.

[0049] <The component (A) having a functional group represented by the general formula (3)> (A) component preferably has a functional group represented by the following general formula (3) and / or the following general formula (4) on at least a part of its surface. -NR 1 R 2 ·····(3) -N + R 1 R 2 R 3 M - ·····(4) (In the above formula (3) and the above formula (4), R 1 , R 2 and R 3 each independently represent a hydrogen atom, or a substituted or unsubstituted hydrocarbon group. M - represents an anion.)

[0050] The functional group represented by the general formula (3) represents an amino group, and the functional group represented by the general formula (4) represents a salt of an amino group. Therefore, the functional group represented by the general formula (3) and the functional group represented by the general formula (4) can be collectively rephrased as "at least one functional group selected from the group consisting of an amino group and a salt thereof". Here, the "(A) component having a functional group represented by the general formula (3) and / or the general formula (4)" means that the functional group represented by the general formula (3) and / or the general formula (4) is covalently fixed on its surface, and does not include those in which a compound having a functional group represented by the general formula (3) and / or the general formula (4) is physically or ionically adsorbed on its surface.

[0051] In the above formula (4), examples of the anion represented by M - include, but are not limited to, OH - , F - , Cl - , Br - , I - , CN - and other anions, and anions derived from acidic compounds.

[0052] In the above formula (3) and the above formula (4), R 1 to R 3 each independently represent a hydrogen atom, or a substituted or unsubstituted hydrocarbon group, but two or more of R 1 to R 3 may combine to form a ring structure.

[0053] R 1 to R 3The hydrocarbon group represented by can be any of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an araliphatic hydrocarbon group, or an alicyclic hydrocarbon group. Further, the aliphatic groups of the aliphatic hydrocarbon group and the araliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or branched. Examples of these hydrocarbon groups include linear, branched, and cyclic alkyl groups, alkenyl groups, aralkyl groups, and aryl groups, etc. Examples thereof include alkenyl groups, aralkyl groups, and aryl groups.

[0054] As the alkyl group, a lower alkyl group having 1 to 6 carbon atoms is preferable, and a lower alkyl group having 1 to 4 carbon atoms is more preferable. Examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an iso-pentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, an n-hexyl group, an iso-hexyl group, a sec-hexyl group, a tert-hexyl group, a cyclopentyl group, a cyclohexyl group, etc.

[0055] As the alkenyl group, a lower alkenyl group having 1 to 6 carbon atoms is preferable, and a lower alkenyl group having 1 to 4 carbon atoms is more preferable. Examples of such an alkenyl group include a vinyl group, an n-propenyl group, an iso-propenyl group, an n-butenyl group, an iso-butenyl group, a sec-butenyl group, a tert-butenyl group, etc.

[0056] As the aralkyl group, those having 7 to 12 carbon atoms are preferable. Examples of such an aralkyl group include a benzyl group, a phenethyl group, a phenylpropyl group, a phenylbutyl group, a phenylhexyl group, a methylbenzyl group, a methylphenethyl group, an ethylbenzyl group, etc.

[0057] The aryl group preferably has 6 to 14 carbon atoms. Examples of such aryl groups include a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,3-xylyl group, 2,4-xylyl group, 2,5-xylyl group, 2,6-xylyl group, 3,5-xylyl group, naphthyl group, anthryl group, and the like.

[0058] The aromatic rings of the above aryl groups and aralkyl groups may have, as substituents, lower alkyl groups such as a methyl group and an ethyl group, a halogen atom, a nitro group, an amino group, a hydroxy group, and the like.

[0059] The component (A) having a functional group represented by the general formula (3) and / or the general formula (4) can be produced, for example, by applying the method described in JP-A-2005-162533. Specifically, silica and an amino group-containing silane coupling agent are sufficiently stirred in an acidic medium, and the amino group-containing silane coupling agent is covalently bonded to the surface of the silica, whereby the component (A) having a functional group represented by the general formula (3) and / or the general formula (4) can be obtained. Here, examples of the amino group-containing silane coupling agent include 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.

[0060] The zeta potential of the component (A) having a functional group represented by the general formula (3) and / or the general formula (4) is a positive potential in the chemical mechanical polishing composition, and the positive potential is preferably +10 mV or more, more preferably +15 mV or more. When the zeta potential of the component (A) having a functional group represented by the general formula (3) and / or the general formula (4) is within the above range, aggregation of particles can be effectively prevented by the electrostatic repulsive force between abrasive grains, and in some cases, a substrate that is negatively charged during chemical mechanical polishing can be selectively polished. Note that the zeta potential measuring device described above can be used. The zeta potential of the component (A) having a functional group represented by the general formula (3) and / or the general formula (4) can be adjusted by appropriately increasing or decreasing the addition amount of the above-described amino group-containing silane coupling agent and the like.

[0061] When the chemical mechanical polishing composition according to this embodiment contains the component (A) having a functional group represented by the general formula (3) and / or the general formula (4), the content of the component (A) is preferably 0.1% by mass or more when the total mass of the chemical mechanical polishing composition is 100% by mass. More preferably, it is 0.3% by mass or more, and particularly preferably 0.5% by mass or more. The content of the component (A) is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less when the total mass of the chemical mechanical polishing composition is 100% by mass. When the content of the component (A) having a functional group represented by the general formula (3) and / or the general formula (4) is within the above range, dishing can be suppressed when polishing a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film, and the storage stability of the chemical mechanical polishing composition may be improved.

[0062] 1.2. (B) Liquid medium The chemical mechanical polishing composition according to this embodiment contains a (B) liquid medium. Examples of the component (B) include water, a mixed medium of water and alcohol, and a mixed medium containing water and an organic solvent compatible with water. Among these, it is preferable to use water or a mixed medium of water and alcohol, and more preferable to use water. The water is not particularly limited, but pure water is preferred. Water may be blended as the remainder of the constituent materials of the chemical mechanical polishing composition, and the content of water is not particularly limited.

[0063] 1.3. (C) Organic acid The chemical mechanical polishing composition according to this embodiment preferably contains a (C) organic acid. By containing the component (C), dishing can be effectively suppressed when polishing a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film.

[0064] (C) component preferably includes a compound having a carboxy group and a compound having a sulfo group. Examples of the compound having a carboxy group include stearic acid, lauric acid, oleic acid, myristic acid, alkenyl succinic acid, lactic acid, tartaric acid, fumaric acid, glycolic acid, phthalic acid, maleic acid, formic acid, acetic acid, oxalic acid, citric acid, malic acid, malonic acid, glutaric acid, succinic acid, benzoic acid, quinolinic acid, cinnamic acid, propionic acid, trifluoroacetic acid; amino acids such as glycine, alanine, aspartic acid, glutamic acid, lysine, arginine, tryptophan, dodecylaminoethylaminoethylglycine, aromatic amino acids, and heterocyclic amino acids; imino acids such as alkyliminodicarboxylic acid; and salts thereof. Further, the (C) component may be a polymer compound having a carboxy group, for example, polyacrylic acid or a salt thereof. Examples of the compound having a sulfo group include amidosulfuric acid; alkylbenzenesulfonic acids such as dodecylbenzenesulfonic acid and p-toluenesulfonic acid; alkylnaphthalenesulfonic acids such as butylnaphthalenesulfonic acid; α-olefinsulfonic acids such as tetradecenesulfonic acid, polystyrenesulfonic acid, and salts thereof. These compounds may be used alone or in combination of two or more.

[0065] When the total mass of the chemical mechanical polishing composition is 100% by mass, the content of the (C) component is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and particularly preferably 0.01% by mass or more. When the total mass of the chemical mechanical polishing composition is 100% by mass, the content of the (C) component is preferably 1% by mass or less, more preferably 0.8% by mass or less, and particularly preferably 0.5% by mass or less. When the content of the (C) component is within the above range, dishing may be more effectively suppressed when polishing a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film.

[0066] In the chemical mechanical polishing composition according to this embodiment, when the content of the component (A) is MA [parts by mass] and the content of the component (C) is MC [parts by mass], it is preferable that MA / MC = 4 to 500. MA / MC is more preferably 6 or more, still more preferably 8 or more, and particularly preferably 10 or more. MA / MC is more preferably 400 or less, still more preferably 200 or less, and particularly preferably 100 or less. MA / M When MA / MC is within the above range, it may be possible to achieve both suppression of foreign matter contamination during the production of the composition and planarization by polishing the surface of a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film.

[0067] 1.4. Other components The chemical mechanical polishing composition according to this embodiment may contain, in addition to the above-described components, an oxidizing agent, a nitrogen-containing heterocyclic compound, a water-soluble polymer, a surfactant, an inorganic acid and its salt, a basic compound, etc., as necessary.

[0068] <Oxidizing agent> The chemical mechanical polishing composition according to this embodiment may contain an oxidizing agent. By containing an oxidizing agent, the surface to be polished of a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be oxidized to promote a complexation reaction with the polishing liquid components, thereby creating a fragile modified layer on the surface to be polished, so that there is an effect of making polishing easier.

[0069] Examples of the oxidizing agent include ammonium persulfate, potassium persulfate, hydrogen peroxide, ferric nitrate, cerium diammonium nitrate, potassium hypochlorite, ozone, potassium periodate, peracetic acid, etc. Among these oxidizing agents, considering the oxidizing power and ease of handling, ammonium persulfate, potassium persulfate, and hydrogen peroxide are preferable, and hydrogen peroxide is more preferable. These oxidizing agents may be used alone or in combination of two or more.

[0070] When the total mass of the chemical mechanical polishing composition is 100% by mass, the content of the oxidizing agent is preferably 0.005% by mass or more, more preferably 0.01% by mass or more. When the total mass of the chemical mechanical polishing composition is 100% by mass, the content of the oxidizing agent is preferably 5% by mass or less, more preferably 3% by mass or less.

[0071] <Nitrogen-containing heterocyclic compound> The chemical mechanical polishing composition according to this embodiment may contain a nitrogen-containing heterocyclic compound. By containing a nitrogen-containing heterocyclic compound, the surface to be polished is protected, so that the occurrence of defects on the surface to be polished may be reduced.

[0072] The nitrogen-containing heterocyclic compound is an organic compound containing at least one heterocyclic ring selected from at least one of a heterocyclic five-membered ring and a heterocyclic six-membered ring having at least one nitrogen atom. Specific examples of the heterocyclic ring include heterocyclic five-membered rings such as pyrrole structure, imidazole structure, triazole structure, thiazoline structure; heterocyclic six-membered rings such as pyridine structure, pyrimidine structure, pyridazine structure, pyrazine structure. The heterocyclic ring may form a condensed ring. Specifically, indole structure, isoindole structure, benzimidazole structure, benzotriazole structure, isothiazoline structure, quinoline structure, isoquinoline structure, quinazoline structure, cinnoline structure, phthalazine structure, quinoxaline structure, acridine structure and the like can be mentioned. Among the heterocyclic compounds having such structures, heterocyclic compounds having a pyridine structure, a quinoline structure, a benzimidazole structure, a benzotriazole structure, and an isothiazoline structure are preferred.

[0073] Specific examples of the nitrogen-containing heterocyclic compound include aziridine, pyridine, pyrimidine, pyrrolidine, piperidine, pyrazine, triazine, pyrrole, imidazole, indole, quinoline, isoquinoline, benzoisoquinoline, purine, pteridine, triazole, triazolidine, benzotriazole, carboxybenzotriazole, isothiazolinone, and derivatives having these skeletons. Among these, it is preferably at least one selected from benzotriazole, isothiazolinone, and triazole. These nitrogen-containing heterocyclic compounds may be used alone or in combination of two or more. They may be used.

[0074] <Water-soluble polymer> The chemical mechanical polishing composition according to the present embodiment may contain a water-soluble polymer. By containing a water-soluble polymer, it may adsorb on the surface of the surface to be polished to reduce polishing friction and reduce the occurrence of dishing on the surface to be polished.

[0075] Examples of the water-soluble polymer include polyacrylamide, polyvinyl alcohol, polyvinylpyrrolidone, polyethyleneimine, polyallylamine, hydroxyethyl cellulose, and the like.

[0076] The weight average molecular weight (Mw) of the water-soluble polymer is preferably 10,000 or more and 1.5 million or less, more preferably 40,000 or more and 1.2 million or less. Here, the "weight average molecular weight" refers to the weight average molecular weight in terms of polyethylene glycol measured by GPC (gel permeation chromatography).

[0077] <Surfactant> The chemical mechanical polishing composition according to this embodiment may contain a surfactant. The surfactant is not particularly limited, and examples thereof include anionic surfactants, cationic surfactants, nonionic surfactants, and the like. Examples of the anionic surfactant include sulfates such as alkyl ether sulfates and polyoxyethylene alkyl phenyl ether sulfates; fluorine-containing surfactants such as perfluoroalkyl compounds. Examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts. Examples of the nonionic surfactant include nonionic surfactants having a triple bond such as acetylene glycol, acetylene glycol ethylene oxide adduct, and acetylene alcohol; polyethylene glycol type surfactants. These surfactants may be used alone or in combination of two or more.

[0078] <Inorganic acids and their salts> The inorganic acid is preferably at least one selected from hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. The inorganic acid may form a salt with a base separately added in the chemical mechanical polishing composition.

[0079] <Basic compounds> Examples of the basic compound include organic bases and inorganic bases. The organic base is preferably an amine, and examples thereof include triethylamine, monoethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzylamine, methylamine, ethylenediamine, diglycolamine, and isopropylamine. Examples of the inorganic base include ammonia, potassium hydroxide, and sodium hydroxide. Among these basic compounds, ammonia and potassium hydroxide are preferred. These basic compounds may be used alone or in combination of two or more.

[0080] 1.5.pH The pH of the chemical mechanical polishing composition according to this embodiment is preferably 1 or more and 7 or less, more preferably 2 or more and 6 or less, and particularly preferably 2.5 or more and 5.5 or less. When the pH is within the above range, the absolute value of the zeta potential of the component (A) in the chemical mechanical polishing composition increases, improving the dispersibility. Thus, polishing can be performed while reducing the occurrence of polishing scratches and dishing on a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film.

[0081] Note that the pH of the chemical mechanical polishing composition according to this embodiment can be adjusted by appropriately increasing or decreasing the content of the component (C), the inorganic acid and its salt, and the basic compound as needed.

[0082] In the present invention, pH refers to the hydrogen ion exponent, and its value can be measured using a commercially available pH meter (for example, a desktop pH meter manufactured by Horiba, Ltd.) under the conditions of 25 °C and 1 atm.

[0083] 1.6. Use The chemical mechanical polishing composition according to this embodiment is suitable as a polishing material for chemically mechanically polishing a semiconductor substrate having a plurality of types of materials constituting a semiconductor device. The semiconductor substrate may have, for example, conductor metals such as copper, tungsten, cobalt, ruthenium, and molybdenum, insulating film materials such as silicon oxide, silicon nitride, and amorphous silicon, and barrier metal materials such as titanium, titanium nitride, tantalum, and tantalum nitride.

[0084] It is particularly preferable that the polishing target of the chemical mechanical polishing composition according to this embodiment is a semiconductor substrate having a site containing at least one of a silicon oxide film and a silicon nitride film. Specific examples of such a semiconductor substrate include a semiconductor substrate having a silicon oxide film formed on the base of a silicon nitride film. According to the chemical mechanical polishing composition according to this embodiment, dishing on the silicon nitride film can be effectively suppressed when polishing such a semiconductor substrate.

[0085] 1.7. Preparation Method of Chemical Mechanical Polishing Composition The chemical mechanical polishing composition according to this embodiment can be prepared by dissolving or dispersing each of the above components in a liquid medium such as water. The method of dissolution or dispersion is not particularly limited, and any method may be applied as long as uniform dissolution or dispersion can be achieved. Also, the mixing order and mixing method of each of the above components are not particularly limited.

[0086] In addition, the chemical mechanical polishing composition according to this embodiment can also be prepared as a concentrated type stock solution and diluted with a liquid medium such as water at the time of use.

[0087] 2. Polishing Method The polishing method according to an embodiment of the present invention includes a step of polishing a semiconductor substrate using the above-described chemical mechanical polishing composition. According to such a chemical mechanical polishing composition, the occurrence of dishing on the polished surface of a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be reduced, and the occurrence of surface defects on the polished surface after polishing can be reduced. Therefore, the polishing method according to this embodiment is particularly suitable, for example, when polishing a semiconductor substrate in which a silicon oxide film is provided on the base of a silicon nitride film. Hereinafter, a specific example of the polishing method according to this embodiment will be described in detail with reference to the drawings.

[0088] 2.1. Object to be Processed FIG. 1 shows an example of an object to be processed 100 suitable for use in the polishing method according to this embodiment. The object to be processed 100 is formed through the following steps (1) to (4).

[0089] (1) First, as shown in FIG. 1, a substrate 10 is prepared. The substrate 10 may be composed of, for example, a silicon substrate and a silicon oxide film formed thereon. Further, functional devices such as transistors may be formed on the substrate 10. Next, on the substrate 10, a first silicon oxide film (thermal oxide film) 12, which is an insulating film, is formed using a thermal oxidation method.

[0090] (2) Next, a second silicon oxide film 14 is formed on the first silicon oxide film 12. The The two silicon oxide films 14 can be formed, for example, by chemical vapor deposition (CVD).

[0091] (3) Next, a photosensitive resist film is formed on the second silicon oxide film 14 by a spin coater, selectively exposed with a photomask, and developed. Then, plasma is irradiated to etch the portion without the resist. Thereafter, the protected resist is removed.

[0092] (4) Next, a silicon nitride film 16 of 1,500 - 2,500 Å is deposited by chemical vapor deposition (CVD). By going through the above steps (1) to (4), the object to be processed 100 can be manufactured.

[0093] 2.2. Polishing method 2.2.1. First polishing step FIG. 2 is a cross-sectional view schematically showing the object to be processed 100 at the end of the first polishing step. As shown in FIG. 2, the first polishing step is a step of roughly polishing the silicon nitride film 16 using a chemical mechanical polishing composition capable of polishing the silicon nitride film 16 at high speed. In the first polishing step, since a chemical mechanical polishing composition capable of polishing the silicon nitride film at high speed is used, surface defects called dishing as shown in FIG. 2 may occur on the surface of the silicon nitride film 16.

[0094] 2.2.2. Second polishing step FIG. 3 is a cross-sectional view schematically showing the object to be processed 100 at the end of the second polishing step. As shown in FIG. 3, the second polishing step is a step of polishing to planarize the silicon oxide film 14 and the silicon nitride film 16 using the chemical mechanical polishing composition of the present invention. Since the chemical mechanical polishing composition of the present invention can control the polishing rate of the silicon nitride film 16 in a well-balanced manner, the occurrence of dishing of the silicon nitride film 16 can be reduced, and the exposed silicon oxide film 14 and silicon nitride film 16 can be planarized by polishing them in a well-balanced manner. Further, since the chemical mechanical polishing composition of the present invention has good dispersibility of the component (A), the occurrence of polishing scratches on the surface to be polished can be reduced.

[0095] 2.3. Polishing Device For the above-described first polishing step and second polishing step, a polishing device 200 as shown in FIG. 4, for example, can be used. FIG. 4 is a perspective view schematically showing the polishing device 200. The above-described first polishing step and second polishing step are performed by supplying slurry (chemical mechanical polishing composition) 44 from a slurry supply nozzle 42 and bringing a carrier head 52 holding a semiconductor substrate 50 into contact therewith while rotating a turntable 48 to which a polishing pad 46 is attached. Note that a water supply nozzle 54 and a dresser 56 are also shown in FIG. 4.

[0096] The polishing load of the carrier head 52 can be selected within the range of 0.7 to 70 psi, preferably 1.5 to 35 psi. Also, the rotational speeds 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 (chemical mechanical polishing composition) 44 supplied from the slurry supply nozzle 42 can be selected within the range of 10 to 1,000 mL / min, preferably 50 to 400 mL / min.

[0097] Examples of commercially available polishing devices include those manufactured by Ebara Corporation, models "EPO-112", "EPO-222", "F-REX300SII"; those manufactured by Lapmaster SFT, models "LGP-510", "LGP-552"; those manufactured by Applied Materials, models "Mirra", "Reflexion"; those manufactured by G&P TECHNOLOGY, models "POLI-400L", "POLI-762", etc.

[0098] 3. Examples Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples in any way. Note that "parts" and "%" in the present examples are based on mass unless otherwise specified.

[0099] 3.1. Preparation of Abrasive Grains <Abrasive Grain A> Tetramethoxysilane and methanol were mixed at a volume ratio of 3:1 so that the total weight was 3000 g to prepare a raw material solution. A reaction solvent prepared by previously mixing methanol, pure water, and 29% ammonia was charged into a reaction tank equipped with a thermometer, a stirrer, a supply pipe, and a distillation line. The concentration of water in the reaction solvent was 15% by mass, and the concentration of ammonia in the reaction solvent was 1% by mass. While maintaining the temperature of the reaction solvent at 20°C, the reaction solvent and the raw material solution were set at a volume ratio of 9.2:1, and the raw material solution was dropped into the reaction tank at a uniform rate for 25 minutes to obtain a silica sol. The obtained silica sol was adjusted in liquid volume by adding pure water so that the content of silica particles became 20% by mass, and while raising the temperature, methanol and ammonia were removed to obtain a precursor of an aqueous dispersion of abrasive grains with a silica particle content of 20% by mass. The obtained precursor of the aqueous dispersion of abrasive grains was stirred for 3 hours under heating and pressurization conditions at 140°C and 0.36 MPa to obtain an aqueous dispersion of abrasive grains A.

[0100] <Abrasive grains A-1> 0.60 g of 3-mercaptopropyltrimethoxysilane was added to 300 g of the aqueous dispersion of abrasive grains A with a silica particle content of 20% by mass, and the mixture was refluxed at the boiling point for 6 hours. Then, while adding pure water to maintain the volume of the dispersion, the by-produced methanol was distilled off. After leaving the dispersion to cool to a temperature of 30°C or lower, 6 g of 35% hydrogen peroxide solution was added, and the dispersion was further reacted for 6 hours while maintaining the temperature at about 70°C. After the reaction was completed, the dispersion was left to cool to a temperature of 30°C or lower to obtain an aqueous dispersion containing abrasive grains A-1 whose surface was modified with sulfonic acid groups.

[0101] <Abrasive grains A-2> To 300 g of an aqueous dispersion of abrasive grains A with a silica particle content of 20% by mass, 0.12 g of 3-mercaptopropyltrimethoxysilane was added, and the mixture was refluxed at the boiling point for 6 hours. Thereafter, while adding pure water to maintain the volume of the dispersion, the by-produced methanol was distilled off. After allowing the dispersion to stand and bringing the temperature to 30°C or lower, 1 g of 35% hydrogen peroxide solution was added, and the reaction was further continued for 6 hours while maintaining the dispersion at about 70°C. After completion of the reaction, the dispersion was allowed to stand and the temperature was brought to 30°C or lower to obtain an aqueous dispersion containing abrasive grains A-2 having the surface of abrasive grains A modified with sulfonic acid groups.

[0102] <Abrasive grains B> An aqueous dispersion of abrasive grains B was obtained in the same manner as the preparation of abrasive grains A, except that the precursor of the aqueous dispersion of abrasive grains was stirred at 140°C and 0.36 MPa under heating and pressurization conditions for 5 hours.

[0103] <Abrasive grains B-1> To 700 g of an aqueous dispersion of abrasive grains B with a silica particle content of 20% by mass, 0.70 g of 3-aminopropyltrimethoxysilane was added, and the mixture was refluxed at the boiling point for 4 hours. Thereafter, while adding pure water to maintain the volume of the dispersion, the by-produced methanol was distilled off. After allowing the dispersion to stand and bringing the temperature to 30°C or lower, a dispersion containing abrasive grains B-1 having the surface of abrasive grains B modified with amino groups was obtained.

[0104] <Abrasive grains B-2> To 700 g of an aqueous dispersion of abrasive grains B with a silica particle content of 20% by mass, 0.14 g of 3-aminopropyltrimethoxysilane was added, and the mixture was refluxed at the boiling point for 4 hours. Thereafter, while adding pure water to maintain the volume of the dispersion, the by-produced methanol was distilled off. After allowing the dispersion to stand and bringing the temperature to 30°C or lower, a dispersion containing abrasive grains B-2 having the surface of abrasive grains B modified with amino groups was obtained.

[0105] <Abrasive grains C> An aqueous dispersion of abrasive grains C was obtained in the same manner as the preparation of abrasive grains A, except that the precursor of the aqueous dispersion of abrasive grains was stirred at 200°C and 1.56 MPa under heating and pressurization conditions for 5 hours.

[0106] <Abrasive grains C-1> 500 g of an aqueous dispersion of abrasive grains C with a silica particle content of 20% by mass was added with 50 g of 29% aqueous ammonia. 2.0 g of 3-(triethoxysilyl)propyl succinic anhydride was added to this dispersion and refluxed at the boiling point for 6 hours. Thereafter, pure water was added to replace ammonia and by-produced methanol with water while maintaining the volume of the dispersion. The addition of pure water was terminated when the pH of the dispersion reached 8.5 or less. The dispersion was left to stand to bring the temperature to 30°C or lower, obtaining a dispersion containing abrasive grains C-1 with the surface of the abrasive grains C modified with carboxy groups.

[0107] <Abrasive grains D> A commercially available silica sol (trade name "PL-3", manufactured by Fuso Chemical Industry Co., Ltd.) was used as it was as abrasive grains D.

[0108] <Abrasive grains E> A commercially available silica sol (trade name "BS-3", manufactured by Fuso Chemical Industry Co., Ltd.) was used as it was as abrasive grains E.

[0109] <Abrasive grains G> A commercially available silica sol (trade name "PL-2L", manufactured by Fuso Chemical Industry Co., Ltd.) was used as it was as abrasive grains G.

[0110] <Abrasive grains H> A commercially available silica sol (trade name "PL-1L-D", manufactured by Fuso Chemical Industry Co., Ltd.) was used as it was as abrasive grains H.

[0111] <Abrasive grains I> A commercially available silica sol (trade name "PL-5-C", manufactured by Fuso Chemical Industry Co., Ltd.) was used as it was as abrasive grains I.

[0112] 3.2. Ratio of surface silanol groups in abrasive grains The ratio of surface silanol groups in the abrasive grains prepared above was determined by obtaining the content x (mass%) of surface silanol groups by the following Shears method and obtaining the content y (mass%) of bulk silanol groups by solid 29 Si-DD / MAS-NMR, and then calculating the value of (x / y)×100 [%].

[0113] <Measurement of the Content of Surface Silanol Groups> An amount equivalent to 1.5 g of silica particles in the aqueous dispersion containing abrasive grains was collected in a 200 mL tall beaker, and pure water was added to make the liquid volume 90 mL. Under an environment of 25 °C, a pH electrode was inserted into the tall beaker, and the test solution was stirred for 5 minutes with a magnetic stirrer. While continuing the stirring with the magnetic stirrer, an aqueous hydrochloric acid solution of 0.1 mol / L was added until the pH reached 3.6. The pH electrode was removed from the tall beaker, and while continuing the stirring with the magnetic stirrer, 30 g of sodium chloride was added, and sodium chloride was completely dissolved while gradually adding pure water. Finally, pure water was added until the total volume of the test solution reached 150 mL, and the test solution was stirred for 5 minutes with a magnetic stirrer to obtain a test solution.

[0114] The tall beaker containing the obtained test solution was set in an automatic titrator (manufactured by Hiranuma Sangyo Co., Ltd., model "COM-1600"), and the pH electrode and burette attached to the apparatus were inserted into the tall beaker. While stirring the test solution with a magnetic stirrer, an aqueous sodium hydroxide solution of 0.1 mol / L was dropped through the burette, and the titration volume A (mL) of the aqueous sodium hydroxide solution of 0.1 mol / L required for the pH to change from 4.0 to 9.0 was measured. Using the following formula (a), the consumption volume V (mL) of the aqueous sodium hydroxide solution of 0.1 mol / L required for the pH to change from 4.0 to 9.0 per 1.5 g of silica particles was calculated, and using the following formula (b), the content x (mass%) of the surface silanol groups of the silica particles was calculated. V=(A×f×100×1.5) / (W×C) (a) A: Titration volume (mL) of the aqueous sodium hydroxide solution of 0.1 mol / L required for the pH to change from 4.0 to 9.0 per 1.5 g of silica particles f: Normality of the aqueous sodium hydroxide solution of 0.1 mol / L used C: Concentration (mass%) of silica particles in the silica sol W: Sampling amount (g) of the silica sol x=(B×17 / M)×100 (b) B: Amount of sodium hydroxide (mol) required for the pH per 1.5 g of silica particles calculated from V to be from 4.0 to 9.0 M: Amount of silica particles (1.5 g)

[0115] <Measurement of the content of bulk silanol groups> The aqueous dispersion containing abrasive grains was freeze-dried to obtain a measurement sample. Using a 400 MHz nuclear magnetic resonance apparatus (manufactured by Varian, model "Varian NMR Systems 400WB"), a probe for CP / MAS with a diameter of 7.5 mm was attached, and the observed nucleus was 29 Si, and measured by the DD / MAS method. The measurement conditions were 29 Si resonance frequency of 79.43 MHz, 29 Si 90° pulse width of 5 μs, 1 H resonance frequency of 399.84 MHz, 1 H decoupling frequency of 50 kHz, MAS rotation speed of 4 kHz, spectral width of 30.49 kHz, and measurement temperature of 23 °C. For data analysis, for each peak of the spectrum after Fourier transform, using the center position, height, and half-width of the peak shape created by the mixture of Lorentz waveform and Gaussian waveform as variable parameters, an optimization calculation was performed by the non-linear least squares method. Targeting the four structural units of Q1, Q2, Q3, and Q4, from the obtained content of Q1, content of Q2, content of Q3, and content of Q4, the content y (mass%) of bulk silanol groups was calculated using the following formula (c). y = {(content of Q3 × 17 + content of Q2 × 17 × 2 + content of Q1 × 17 × 3) / (60 + content of Q3 × 1 + content of Q2 × 2 + content of Q1 × 3)} × 100 (c)

[0116] 3.3. Preparation of chemical mechanical polishing composition Each component was mixed so as to have the composition shown in Table 1 to Table 2 below, and further adjusted by adding an aqueous potassium hydroxide solution (manufactured by Kanto Chemical Co., Inc., trade name "48% aqueous potassium hydroxide solution") or nitric acid (manufactured by Kanto Chemical Co., Inc., trade name "Nitric acid 1.38") as required so as to have the pH shown in Table 1 to Table 2 below. Pure water was added so that the total amount of all components was 100% by mass, and the chemical mechanical polishing compositions of each example and each comparative example were prepared.

[0117] 3.4. Evaluation Method 3.4.1. Flatness Evaluation As the object to be processed, a 12-inch wafer with a 100-nm silicon oxide film formed thereon was processed into a "SEMATECH 754" pattern with a depth of 100 nm, and a test substrate (manufactured by SEMATECH INTERNATIONAL) with a 200-nm silicon nitride film laminated thereon was used. For this test substrate, polishing was performed under the following conditions until the silicon oxide film was exposed. The polished surface after the polishing treatment was measured using a stylus profiling system (manufactured by BRUK ER, model "Dektak XTL") to confirm the step (dishing) of the silicon nitride film / silicon oxide film lines in the pattern portion where the silicon nitride film line width (line, L) / silicon oxide film line width (space, S) was 0.18 μm / 0.18 μm, respectively. <Polishing Conditions> · Polishing apparatus: manufactured by AMAT, model "Reflexion LK" · Polishing pad: manufactured by Fuji Spinning Co., Ltd., "Multi-hard polyurethane pad; H800-type1(3-1S)775" · Supply rate of the chemical mechanical polishing composition: 300 mL / min · Platen rotation speed: 100 rpm · Head rotation speed: 90 rpm · Head pressing pressure: 2.5 psi

[0118] The evaluation criteria for flatness evaluation are as follows. The evaluation results are shown together in Table 1 to Table 2 below. (Evaluation Criteria) · "A"… When the dishing amount is less than 6.0 nm, it is determined that the flatness is very good. · "B"… When the dishing amount is 6.0 nm or more, it is determined that the flatness is poor.

[0119] 3.4.2. Equipment Damage Evaluation In the manufacturing equipment for chemical mechanical polishing compositions, resin materials such as polypropylene, polyethylene, polyvinyl chloride, and polytetrafluoroethylene are combined and used. When manufacturing a chemical mechanical polishing composition, damage to the equipment, such as wear of the equipment piping by the abrasive grains contained in the composition, becomes a problem. Damage to the equipment piping caused by abrasive grains is particularly often a problem in polypropylene. Therefore, as an index reflecting equipment damage during the production of a chemical mechanical polishing composition, equipment damage evaluation was performed by measuring the amount of abrasion when spraying the chemical mechanical polishing composition onto a commercially available polypropylene resin.

[0120] A square polypropylene resin (manufactured by AS ONE Corporation, model number "64-6379-01") with a side length of 3 cm and a thickness of 2 mm was installed in a micro slurry erosion test apparatus (manufactured by Palmesso Co., Ltd., model number "MSE-A"). The chemical mechanical polishing compositions described in each example and each comparative example were sprayed onto the polypropylene resin 20 g at a time, for a total of 4 times, under the conditions of an air flow rate of 11.0 L / min and a slurry flow rate of 125 mL / min. The average value of the amount of abrasion of the polypropylene resin during the second, third, and fourth sprayings was calculated. The evaluation criteria are as follows. The evaluation results are shown together in Table 1 to Table 2 below. (Evaluation Criteria) · "A": When the amount of abrasion of the polypropylene resin is less than 10 nm per spray, it is judged that the damage to the equipment during the actual production of the chemical mechanical polishing composition is extremely small, there is no risk of foreign matter contamination, and it is extremely good. · "B": When the amount of abrasion of the polypropylene resin is 10 nm or more and less than 20 nm per spray, it is judged that the damage to the equipment during the actual production of the chemical mechanical polishing composition is sufficiently small and the risk of foreign matter contamination is also low, so it is judged to be very good. · "C": When the amount of abrasion of the polypropylene resin is 20 nm or more and less than 30 nm per spray, it is judged that the damage to the equipment during the actual production of the chemical mechanical polishing composition is within the allowable range and the risk of foreign matter contamination is also low, so it is judged to be good. · When the amount of shaving of the polypropylene resin is 30 nm or more per injection, it is judged to be defective because the damage to the equipment during the actual production of the chemical mechanical polishing composition is large and the risk of foreign matter contamination is high.

[0121] 3.5. Evaluation Results The following Table 1 to Table 2 show the compositions of the chemical mechanical polishing compositions of each example and each comparative example and each evaluation result.

[0122]

Table 1

[0123]

Table 2

[0124] Each component in the above Table 1 to Table 2 used the following products or reagents, respectively. <Organic Acid> · Maleic acid: manufactured by Fujifilm Wako Pure Chemical Corporation, product name "Maleic Acid" · Acetic acid: manufactured by Kanto Chemical Co., Inc., product name "Acetic Acid" · Citric acid: manufactured by Fuso Chemical Industry Co., Ltd., product name "Purified Citric Acid (Crystal) L" · Malonic acid: manufactured by Kanto Chemical Co., Inc., product name "Malonic Acid" · Tartaric acid: manufactured by Fujifilm Wako Pure Chemical Corporation, product name "L(+)-Tartaric Acid" · Polystyrene sulfonic acid: manufactured by Shima Trading Co., Ltd., product name "VERSA-TL502", weight average molecular weight (Mw) = 1,000,000 · Sodium dodecyliminodipropionate: manufactured by Takemoto Yushi Co., Ltd., product name "TAKESURF C-158D" · Dipotassium alkenyl succinate: manufactured by Kao Corporation, product name "LATEMUL ASK" <Oxidizing Agent> · Hydrogen peroxide: manufactured by Fujifilm Wako Pure Chemical Corporation, product name "Hydrogen Peroxide" (30% aqueous solution) · Orthoperiodic acid: manufactured by Fujifilm Wako Pure Chemical Corporation, product name "Orthoperiodic Acid" <Nitrogen-containing Heterocyclic Compound> · Isothiazolinone: Manufactured by Sigma-Aldrich, trade name "2-Methyl-4-isothiazolin-3-one" <Water-soluble polymer> · Polyvinylpyrrolidone: Manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Polyvinylpyrrolidone K-90", weight-average molecular weight (Mw) = 360,000 <Inorganic acid> · Nitric acid: Manufactured by Kanto Chemical Co., Inc., trade name "Nitric acid 1.38" (60-61% aqueous solution) · Sulfuric acid: Manufactured by Kanto Chemical Co., Inc., trade name "High-purity sulfuric acid (96%)" (96% aqueous solution) · Phosphoric acid: Manufactured by Lasa Industries Co., Ltd., trade name "85% Phosphoric acid" (85% aqueous solution) <Basic compound> · Monoethanolamine: Manufactured by Hayashi Pure Chemical Industries, Ltd., trade name "Ethanolamine" · Ammonia: Manufactured by Fujifilm Wako Pure Chemical Corporation, trade name "Ammonia water" (29% aqueous solution) · Tetraethylammonium hydroxide: Manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Tetraethylammonium Hydroxide" (35% aqueous solution)

[0125] According to the evaluation results in Table 1 to Table 2 above, when the chemical mechanical polishing compositions of Examples 1 to 11 were used, good flatness was achieved in all cases, and the damage to the manufacturing equipment during the production of the chemical mechanical polishing composition could be significantly reduced, and it was found that the risk of foreign matter contamination was low.

[0126] Comparative Examples 1 to 4 are examples using a chemical mechanical polishing composition containing abrasive grains in which the ratio of silanol groups present on the surface represented by (x / y) × 100 [%] exceeds 15% and which do not have any of the functional groups represented by General Formulas (1) to (4). In this case, in addition to the flatness being outside the allowable range, the damage to the manufacturing equipment also resulted in an unacceptable result, and it was found that the risk of foreign matter contamination was high.

[0127] Comparative Examples 5 and 6 are examples in which the ratio of silanol groups present on the surface represented by (x / y)×100[%] exceeds 15%, but a chemical mechanical polishing composition containing abrasive grains having a sulfo group or an amino group is used. In this case, while the damage to the manufacturing equipment was within the allowable range, the flatness was outside the allowable range.

[0128] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations having the same functions, methods, and results, or configurations having the same objectives and effects). Further, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Further, the present invention includes configurations that exhibit the same operational effects as the configurations described in the embodiments or configurations that can achieve the same objectives. Further, the present invention includes configurations in which known techniques are added to the configurations described in the embodiments.

Explanation of Reference Numerals

[0129] 10... Substrate, 12... First silicon oxide film, 14... Second silicon oxide film, 16... Silicon nitride film, 42... Slurry supply nozzle, 44... Slurry (chemical mechanical polishing composition), 46... Polishing pad, 48... Turntable, 50... Semiconductor substrate, 52... Carrier head, 54... Water supply nozzle, 56... Dresser, 100... Object to be processed, 200... Polishing apparatus

Claims

1. (A) abrasive grains containing silica, and (B) a liquid medium, The chemical mechanical polishing composition contains, When the content ratio of the surface silanol groups measured by the shear method of the component (A) is x [mass%] and the content ratio of the bulk silanol groups measured by Si-DD / MAS-NMR is y [mass%], the ratio of the silanol groups present on the surface represented by (x / y) × 100 [%] is 15% or less, ２９ and The component (A) is a chemical mechanical polishing composition having at least one functional group selected from the functional groups represented by the following general formulas (1) to (4). -SO ３ － M ＋ ......(1) -COO － M ＋ ...... (2) (In the above formulas (1) and (2), M ＋ represents a monovalent cation.) -NR １ R ２ ・・・・・(3) -N ＋ R １ R ２ R ３ M － ・・・・・(4) (In the above formulas (3) and (4), R １ , R ２ , and R ３ each independently represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group. M － represents an anion.)

2. The chemical mechanical polishing composition according to claim 1, wherein the component (A) is abrasive grains containing silica particles in which at least one functional group selected from the functional groups represented by the general formulas (1) to (4) is fixed to the surface via a covalent bond.

3. Furthermore, (C) The chemical mechanical polishing composition according to claim 1 or claim 2, which contains an organic acid.

4. The chemical mechanical polishing composition according to claim 3, wherein the component (C) contains at least one selected from the group consisting of acetic acid, malonic acid, citric acid, maleic acid, and tartaric acid.

5. The chemical mechanical polishing composition according to claim 1 or claim 2, having a pH of 1 or more and 7 or less.

6. The chemical mechanical polishing composition according to claim 1 or claim 2, wherein the content of the component (A) is 0.1% by mass or more and 20% by mass or less with respect to 100% by mass of the chemical mechanical polishing composition.

7. A polishing method including a step of polishing a semiconductor substrate using the chemical mechanical polishing composition according to claim 1 or claim 2.

8. The polishing method according to claim 7, wherein the semiconductor substrate includes a portion containing a silicon oxide film and a silicon nitride film.

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