Composition for chemical mechanical polishing and polishing method

Abstract

To provide a composition for chemical mechanical polishing and a polishing method that effectively suppress contamination of foreign matters during manufacturing and 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 aspect ratio of abrasive grains is x, which is the ratio x2 / x1 of the short diameter x1 and the long diameter x2 measured by field emission scanning electron microscopy, and the aggregation ratio is y, which is the ratio y2 / y1 of the average primary particle diameter y1 calculated from the BET specific surface area and the average secondary particle diameter y2 measured by the DLS method, x / y is 0.63 to 0.75, and the abrasive grain has at least one functional group selected from the functional groups represented by the following general formulae (1) to (4), -SO3-M+ (1), -COO-M+ (2), -NR1R2 (3), -N+R1R2R3M- (4), M+ represents a monovalent cation, M- represents an anion, and R1 to R3 each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group.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 the planarization of an interlayer insulating film, the formation of a metal plug, and the formation of embedded wiring (damascene wiring) in a multilayer wiring formation process. In order to achieve 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 production and can polish the surface of a semiconductor substrate to a flat surface. [Means for solving the problem]

[0007] One aspect of the chemical mechanical polishing composition of the present invention is (A) an abrasive grain containing silica; (B) a liquid medium; A chemical mechanical polishing composition comprising: In the component (A), when the aspect ratio x2 / x1, which is the ratio of the minor axis x1 to the major axis x2 measured by a field emission scanning electron microscope, is defined as x, and the association ratio y2 / y1, which is the ratio of the average primary particle diameter y1 calculated from the BET specific surface area to the average secondary particle diameter y2 measured by a DLS method, is defined as y, x / y is 0.63 to 0.75, 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. - represents an anion.)

[0008] In one embodiment 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 is 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.

Effect 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 including numerical value X as the lower limit value and including numerical value Y as the upper limit value.

[0019] 1. Chemical Mechanical Polishing Composition The chemical mechanical polishing composition according to one 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). When the aspect ratio, which is the ratio x2 / x1 of the minor axis x1 and the major axis x2 measured by a field emission scanning electron microscope in the (A) component, is x, and the aggregation ratio, which is the ratio y2 / y1 of the average primary particle diameter y1 calculated from the BET specific surface area and the average secondary particle diameter y2 measured by the DLS method, is y, x / y is 0.63 to 0.75, and the (A) component 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 chemical mechanical polishing composition according to the present 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. For the component (A), when the aspect ratio, which is the ratio x2 / x1 of the minor axis x1 and the major axis x2 measured by a field emission scanning electron microscope, is x, and the aggregation ratio, which is the ratio y2 / y1 of the average primary particle diameter y1 calculated from the BET specific surface area and the average secondary particle diameter y2 measured by the DLS method, is y, x / y satisfies the relationship of 0.63 to 0.75. When x / y in the component (A) is within the above range, aggregation or sedimentation of the component (A) in the composition is suppressed, so that the surface of the semiconductor substrate can be polished flat.

[0021] x is the aspect ratio represented by the ratio x2 / x1 of the minor axis x1 and the major axis x2 measured by a field emission scanning electron microscope. x is preferably 1.20 to 1.38, more preferably 1.21 to 1.37. When x is at least the lower limit value, the polishing rate for a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film is excellent, and the productivity is excellent. Further, when x is at most the upper limit value, dishing and polishing scratches on the semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be reduced, and sedimentation of the component (A) in the composition can be suppressed.

[0022] x1 is the minor axis measured by a field emission scanning electron microscope. x1 is preferably 8 nm to 160 nm, more preferably 16 nm to 80 nm. When x1 is at least the lower limit value, the storage stability of the component (A) is excellent. Further, when x1 is at most the upper limit value, dishing and polishing scratches on the semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be reduced, and sedimentation of the component (A) in the composition can be suppressed.

[0023] x2 is the major axis measured by a field emission scanning electron microscope. x2 is preferably 10 nm to 200 nm, more preferably 20 nm to 100 nm. When x2 is at least the lower limit value, the storage stability of the component (A) is excellent. Further, when x2 is at most the upper limit value, dishing and polishing scratches on the semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be reduced, and sedimentation of the component (A) in the composition can be suppressed.

[0024] (A) component's minor axis x1 and major axis x2 are measured by a field emission scanning electron microscope. Specifically, they are measured and calculated under the conditions shown below. Drop the aqueous dispersion containing the (A) component onto a silicon substrate and dry it. Using a field emission scanning electron microscope, irradiate the silicon substrate with an electron beam at an acceleration voltage of 5 kV, take a secondary electron image observed at a magnification of 50,000 times, measure the minor axis and major axis of all the particles (100 to 130 particles) contained in the same field of view, and calculate their respective average values. At that time, adjust the concentration of the (A) component in the silica sol so that the total number of silica particles contained in the same field of view of the secondary electron image observed at a magnification of 50,000 times is 100 to 130 particles. The reason for setting the magnification to 50,000 times is that the shape of each particle with a minor axis of 16 nm to 80 nm and a major axis of 20 nm to 100 nm can be identified, and the amount of these particles contained in the same field of view can be ensured sufficiently (100 to 130 particles).

[0025] y is the association ratio represented by the ratio y2 / y1 of the average primary particle diameter y1 calculated from the BET specific surface area and the average secondary particle diameter y2 measured by the DLS method. y is preferably 1.74 to 1.92, more preferably 1.75 to 1.91. When y is at least the lower limit value, the polishing rate for a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film is excellent, and the productivity is excellent. Also, when y is at most the upper limit value, dishing and polishing scratches on a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be reduced, and sedimentation of the (A) component in the composition can be suppressed.

[0026] y1 is the average primary particle diameter calculated from the BET specific surface area. y1 is preferably 5 nm to 100 nm, more preferably 10 nm to 60 nm. When y1 is at least the lower limit value, the storage stability of the (A) component is excellent. Also, when y1 is at most the upper limit value, dishing and polishing scratches on a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film can be reduced, and sedimentation of the (A) component in the composition can be suppressed.

[0027] ​The average primary particle diameter of the (A) component is measured by the BET method. Specifically, the specific surface area of the (A) component is measured using a specific surface area automatic measuring device, and assuming that the (A) component is a true sphere, the average primary particle diameter is calculated using the following formula (a). Average primary particle diameter (nm) = 6000 / (specific surface area (m 2 / g) × density (g / cm 3 )) (a)

[0028] y2 is the average secondary particle diameter measured by the DLS method. y2 is preferably from 9.5 nm to 190 nm, more preferably from 19 nm to 110 nm. When y2 is at or above the lower limit value, the storage stability of the (A) component is excellent. Also, when y2 is at or below the upper limit value, the dishing and polishing scratches of the semiconductor substrate containing the silicon oxide film and / or silicon nitride film can be reduced, and the sedimentation of the (A) component in the composition can be suppressed.

[0029] The average secondary particle diameter of the (A) component is measured by the DLS method. Specifically, it is measured using a dynamic light scattering particle size measuring device.

[0030] x / y is from 0.63 to 0.75, preferably from 0.64 to 0.74, more preferably from 0.65 to 0.73. When x / y is at or above the lower limit value, the dispersibility of the (A) component in the composition is excellent. Also, when x / y is at or below the upper limit value, the storage stability of the composition is excellent.

[0031] x / y can be set within a desired range by controlling the aggregation state of the (A) component in the silica sol. To control the aggregation state of the (A) component in the composition, for example, the composition ratio of the raw material alkoxysilane to the solvent / dispersion medium, the reaction temperature, the reaction time, etc. may be optimized.

[0032] The (A) component is abrasive grains mainly composed of silica, but may contain other components. Examples of the other components include aluminum compounds and silicon compounds. By further containing an aluminum compound or a silicon compound in the (A) component, the surface hardness of the (A) component 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. In addition, the occurrence of 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 in some cases.

[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 silicone resin.

[0034] The average particle size of the (A) 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 size 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 without causing sedimentation and separation of particles may be obtained. The average particle size of the (A) component can be determined, 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] When the total mass of the chemical mechanical polishing composition is 100% by mass, the content of 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 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 content of component (A) 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] Component (A) 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] At least a part of the surface of the abrasive grains of component (A) being modified with at least one functional group selected from the functional groups represented by the general formulas (1) to (4) has, particularly in the range where the pH is 1 or more and 7 or less, a larger absolute value of the zeta potential than 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. Further, 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 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 general formulas (1) to (4), the functional group may 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 general formula (1)> Component (A) may have a functional group represented by the following general formula (1) on at least a part of its surface. -SO3 - M + ·····(1) (M + represents a monovalent cation.)

[0040] In the above formula (1), M + The monovalent cation represented by is not limited to these, but for example, H + 、Li + 、Na + 、K + 、NH4 +include. That is, the functional group represented by the general formula (1) can also be paraphrased as "at least one functional group selected from the group consisting of a sulfo group and its salts". Here, the "salt of a sulfo group" refers to a functional group in which the hydrogen ion contained in the sulfo group (-SO3H) is replaced by a monovalent cation such as Li + Na + K + NH4 + and the like. Here, the "(A) component having a functional group represented by the general formula (1)" refers to one in which the functional group represented by the general formula (1) is fixed to its surface via a covalent bond, and does not include those in which a compound having a functional group represented by the general formula (1) is physically or ionically adsorbed on its surface.

[0041] The (A) component 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. Specifically, silica and a mercapto group-containing silane coupling agent are sufficiently stirred in an acidic medium to covalently bond the mercapto group-containing silane coupling agent to the surface of the silica. Here, examples of the mercapto group-containing silane coupling agent include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and the like. Next, an appropriate amount of hydrogen peroxide is further added and left standing sufficiently to obtain the (A) component having a functional group represented by the 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 positively charged substrate can be selectively polished during chemical mechanical polishing. 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, 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 + . Here, the "(A) component having a functional group represented by the general formula (2)" refers to a component in which the functional group represented by the general formula (2) is fixed to its surface via a covalent bond, and does not include a component 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 3-(triethoxysilyl)propyl succinic anhydride.

[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, "(Component A) 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, for example , 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 ~R 3 each independently represent a hydrogen atom, or a substituted or unsubstituted hydrocarbon group, provided that two or more of R 1 ~R 3 may combine to form a ring structure.

[0053] R 1 ~R 3The hydrocarbon group represented by may 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.

[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, and the like.

[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, and the like.

[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, and the like.

[0057] As the aryl group, those having 6 to 14 carbon atoms are preferable. Examples of such an aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 2,3-xylyl group, a 2,4-xylyl group, a 2,5-xylyl group, a 2,6-xylyl group, a 3,5-xylyl group, a naphthyl group, an 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 methyl group and ethyl group, halogen atoms, nitro groups, amino groups, hydroxy groups 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 to covalently bond the amino group-containing silane coupling agent to the surface of 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, the electrostatic repulsive force between abrasive grains effectively prevents aggregation of the particles, and in some cases, a substrate having a negative charge 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, 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 (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 it is 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] As component (C), compounds having a carboxy group and compounds having a sulfo group are preferable. 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, component (C) 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 component (C) is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, 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 component (C) 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 component (C) is within the above range, dishing can be more effectively suppressed when polishing a semiconductor substrate containing a silicon oxide film and / or a silicon nitride film.

[0066] Regarding 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. 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, which has the 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 Structures, quinoxaline structures, acridine structures, etc. are 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.

[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 adducts, 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. Note that 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, isopropylamine, and the like. Examples of the inorganic base include ammonia, potassium hydroxide, sodium hydroxide, and the like. 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, a conductor metal such as copper, tungsten, cobalt, ruthenium, molybdenum, etc., an insulating film material such as silicon oxide, silicon nitride, amorphous silicon, etc., and a barrier metal material such as titanium, titanium nitride, tantalum, tantalum nitride, etc.

[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. Method for Preparing 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 dissolving or dispersing is not particularly limited, and any method may be applied as long as it can be uniformly dissolved or dispersed. Also, the mixing order and mixing method of each of the above components are not particularly limited.

[0086] Further, the chemical mechanical polishing composition according to this embodiment can be prepared as a concentrated type stock solution and diluted with a liquid medium such as water at the time of use before 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 chemical mechanical polishing composition. According to such a chemical mechanical polishing composition, the occurrence of dishing on the surface to be polished 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 surface to be polished 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 formed 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 Treated FIG. 1 shows an example of an object to be treated 100 suitable for use in the polishing method according to this embodiment. The object to be treated 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 second silicon oxide film 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 using 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). The object to be processed 100 can be fabricated through the above steps (1) to (4).

[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 rapidly polishing the silicon nitride film. In the first polishing step, since a chemical mechanical polishing composition capable of rapidly polishing the silicon nitride film 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 the silicon oxide film 14 and the silicon nitride film 16 using the composition for chemical mechanical polishing of the present invention in order to planarize them. Since the composition for chemical mechanical polishing 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 composition for chemical mechanical polishing 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 Apparatus For the above-described first polishing step and second polishing step, for example, a polishing apparatus 200 as shown in FIG. 4 can be used. FIG. 4 is a perspective view schematically showing the polishing apparatus 200. The above-described first polishing step and second polishing step are performed by supplying a slurry (composition for chemical mechanical polishing) 44 from a slurry supply nozzle 42 and bringing a carrier head 52 holding a semiconductor substrate 50 into contact while rotating a turntable 48 to which a polishing pad 46 is attached. In addition, 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. Further, the rotation 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 (composition for chemical mechanical polishing) 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 apparatuses include, for example, 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. In addition, "parts" and "%" in this example 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 obtained 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 speed for 25 minutes to obtain a silica sol. The obtained silica sol was heated to remove methanol and ammonia while adjusting the liquid volume by adding pure water so that the content rate of silica particles became 20% by mass, and a precursor of an aqueous dispersion of abrasive grains with a silica particle content rate of 20% by mass was obtained. 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 grain A.

[0100] <Abrasive grain A-1> To 300 g of an aqueous dispersion of abrasive grains A with a silica particle content of 20% by mass, 0.60 g of 3-mercaptopropyltrimethoxysilane was added, 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 allowing the dispersion to stand and bringing the temperature to 30°C or lower, 6 g of 35% hydrogen peroxide solution was added, and the reaction was further carried out 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-1 whose surface of abrasive grains A was modified with sulfonic 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. Then, 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 carried out 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 whose surface of abrasive grains A was modified with sulfonic 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 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. Then, 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 whose surface of abrasive grains B was 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. The dispersion was left to stand to bring the temperature to 30°C or lower, thereby obtaining a dispersion containing abrasive grains B-2 whose surface was modified with amino groups.

[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 for 5 hours under heating and pressurization conditions.

[0106] <Abrasive grains C-1> To 500 g of an aqueous dispersion of abrasive grains C with a silica particle content of 20% by mass, 50 g of 29% aqueous ammonia was added. 2.0 g of 3-(triethoxysilyl)propyl succinic anhydride was added to this dispersion, and the mixture was refluxed at the boiling point for 6 hours. Thereafter, while adding pure water to maintain the volume of the dispersion, ammonia and the by-produced methanol were replaced with water. The addition of pure water was terminated when the pH of the dispersion reached 8.5 or lower. The dispersion was left to stand to bring the temperature to 30°C or lower, thereby obtaining a dispersion containing abrasive grains C-1 whose surface was 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> Commercially available silica sol (trade name "PL-5-C", manufactured by Fuso Chemical Industry Co., Ltd.) was used as it is as the abrasive grains I.

[0112] 3.2. Measurement of x / y Measurement of the minor axis x1 and major axis x2 of component (A) The aqueous dispersion containing the abrasive grains prepared above was diluted 5000-fold with pure water, and 5 μL of the diluted aqueous dispersion was dropped onto a silicon substrate and dried. Then, using a field emission scanning electron microscope (manufactured by Hitachi High-Tech Corporation, model name "S-5200"), an electron beam was irradiated on the silicon substrate at an acceleration voltage of 5 kV, and a secondary electron image observed at a magnification of 50,000 times was photographed. The minor axis and major axis of component (A) (100 to 130 pieces) contained in the same visual field were measured, and the average value of each was calculated. The minor axis of component (A) was designated as x1, and the major axis of component (A) was designated as x2. From the obtained values of the minor axis x1 and major axis x2, the value of x = x2 / x1 was determined. In addition, the measurement of the minor axis x1 and major axis x2 of component (A) was performed by importing the photographed field emission scanning electron microscope photograph into image analysis type particle size distribution measurement software (manufactured by Mountech Co., Ltd., software name "Mac-View Ver.4"). Whether two or more particles were joined or not was determined as individual non-joined particles when a black line was visible between the particles, and as one joined particle when no black line was visible between the particles.

[0113] 3.2.2. Measurement of the average primary particle diameter The aqueous dispersion containing the abrasive grains prepared above was freeze-dried, and the specific surface area of component (A) was measured using a specific surface area automatic measurement device (manufactured by MicrotracBEL Corp., model "Belsorp MR1"). Assuming that component (A) is a perfect sphere, using the following formula (a) and with a density of 2.2 g / cm 3 the average primary particle diameter y1 was calculated. Average primary particle diameter (nm) = 6000 / (specific surface area (m 2 / g) × density (g / cm 3 )) (a)

[0114] 3.2.3. Measurement of average secondary particle diameter The aqueous dispersion containing the abrasive grains prepared above was used to measure the average secondary particle diameter y2 of component (A) under volume conversion conditions using a dynamic light scattering particle size measuring device (manufactured by Malvern, model "Zetasizer Nano ZS"). From the obtained values of the average primary particle diameter y1 and the average secondary particle diameter y2, the value of y = y2 / y1 was determined.

[0115] 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, 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") was added as necessary to adjust the pH to that 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.

[0116] 3.4. Evaluation method 3.4.1. Flatness evaluation As the object to be processed, a 12-inch wafer on which a 100-nm silicon oxide film was formed was processed into a "SEMATECH 754" pattern with a depth of 100 nm, and a test substrate (manufactured by SEMATECH INTERNATIONAL) on which a 200-nm silicon nitride film was further laminated was used. This test substrate was polished under the following conditions until the silicon oxide film was exposed. The polished surface after the polishing treatment was used with a stylus profilometry system (manufactured by BRUKER, model "Dektak XTL") to confirm the step (dishing) of the silicon nitride film / silicon oxide film line at 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 chemical mechanical polishing composition: 300 mL / min · Rotation speed of the surface plate: 100 rpm · Rotation speed of the head: 90 rpm · Head pressing pressure: 2.5 psi

[0117] 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 judged that the flatness is very good. · "B"... When the dishing amount is 6.0 nm or more, it is judged that the flatness is poor.

[0118] 3.4.2. Equipment damage evaluation In the manufacturing equipment for the chemical mechanical polishing composition, resin materials such as polypropylene, polyethylene, polyvinyl chloride, and polytetrafluoroethylene are combined and used. When manufacturing the 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 by the abrasive grains often causes problems particularly in polypropylene. Therefore, as an index reflecting the equipment damage during the production of the chemical mechanical polishing composition, the equipment damage evaluation was performed by measuring the amount of abrasion when the chemical mechanical polishing composition was sprayed onto a commercially available polypropylene resin.

[0119] 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 in an amount of 20 g each, 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 polypropylene resin shaved is less than 10 nm per injection, it is judged to be extremely good because 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. · "B"... When the amount of polypropylene resin shaved is 10 nm or more and less than 20 nm per injection, it is judged to be very good because 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. · "C"... When the amount of polypropylene resin shaved is 20 nm or more and less than 30 nm per injection, it is judged to be good because 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. · "D"... When the amount of polypropylene resin shaved 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.

[0120] 3.5. Evaluation Results The following Table 1 to Table 2 show the composition of the chemical mechanical polishing composition for each example and each comparative example and each evaluation result.

[0121]

Table 1

[0122]

Table 2

[0123] 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, product name "2-Methyl-4-isothiazolin-3-one" <Water-soluble polymer> · Polyvinylpyrrolidone: manufactured by Tokyo Chemical Industry Co., Ltd., product name "Polyvinylpyrrolidone K-90", weight average molecular weight (Mw) = 360,000 <Inorganic acid> · Nitric acid: manufactured by Kanto Chemical Co., Inc., product name "Nitric acid 1.38" (60 - 61% aqueous solution) · Sulfuric acid: manufactured by Kanto Chemical Co., Inc., product name "High-purity sulfuric acid (96%)" (96% aqueous solution) · Phosphoric acid: manufactured by Lasa Industries Co., Ltd., product name "85% Phosphoric acid" (85% aqueous solution) <Basic compound> · Monoethanolamine: manufactured by Hayashi Pure Chemical Industries, Ltd., product name "Ethanolamine" · Ammonia: manufactured by FUJIFILM Wako Pure Chemical Corporation, product name "Ammonia water" (29% aqueous solution) · Tetraethylammonium hydroxide: manufactured by Tokyo Chemical Industry Co., Ltd., product name "Tetraethylammonium Hydroxide" (35% aqueous solution)

[0124] 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 damage to the manufacturing equipment during the production of the chemical mechanical polishing composition could be significantly reduced, indicating that the risk of foreign matter contamination was low.

[0125] Comparative Examples 1 to 4 are examples using a chemical mechanical polishing composition containing abrasive grains that are outside the range of 0.63 to 0.75 for x / y and 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 a value outside the allowable range, indicating that the risk of foreign matter contamination was high.

[0126] Comparative Examples 5 and 6 are examples using a chemical mechanical polishing composition containing abrasive grains having a sulfo group or an amino group although x / y is outside the range of 0.63 to 0.75. In this case, while the damage to the manufacturing equipment was within the allowable range, the flatness was outside the allowable range.

[0127] 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 purposes and effects). Further, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Moreover, the present invention includes configurations having the same operational effects as the configurations described in the embodiments or configurations capable of achieving the same purposes. In addition, the present invention includes configurations in which known technologies are added to the configurations described in the embodiments.

Explanation of Reference Numerals

[0128] 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, (B) a liquid medium, A chemical mechanical polishing composition containing: In the component (A), when the aspect ratio, which is the ratio x2 / x1 of the minor axis x1 and the major axis x2 measured by a field emission scanning electron microscope, is x, and the association ratio, which is the ratio y2 / y1 of the average primary particle diameter y1 calculated from the BET specific surface area and the average secondary particle diameter y2 measured by the DLS method, is y, x / y is 0.63 to 0.75, 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 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.

3. Furthermore, (C) an organic acid is contained, and the chemical mechanical polishing composition according to claim 1 or claim 2.

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.

Images