KR20190112636A - Polishing composition - Google Patents

Abstract

Provided by the present invention is a polishing composition capable of polishing an object including silicon nitride with higher selectivity to silicon oxide or polysilicon. The polishing composition contains grains and at least one compound selected from a group consisting of a compound represented by formula 1 and salt thereof. In formula 1, R^1 is a substituted or unsubstituted hydrocarbon group having 6 to 30 carbon atoms; R^2 is a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; X is a single bond or -CO-; and Y is a bivalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.

Description

Polishing composition {POLISHING COMPOSITION}

The present invention relates to a polishing composition.

In recent years, due to the high integration caused by the miniaturization of LSI manufacturing processes, electronic devices including computers have been performing high performance such as miniaturization, multifunctionalization, and high speed. In the novel micromachining technique with high integration of such LSI, a chemical mechanical polishing (CMP) method is used. The CMP method is a technique frequently used in the planarization of the interlayer insulating film, the metal plug formation, and the buried wiring (tamascene wiring) in the LSI manufacturing process, particularly in the multilayer wiring formation process.

CMP is applied to each process in semiconductor manufacturing, As an aspect, the application to the gate formation process in transistor manufacture is mentioned, for example.

In transistor fabrication, Si-containing materials such as polycrystalline silicon (polysilicon), silicon oxide, and silicon nitride may be polished, and it is required to control the polishing rate of each Si-containing material. For example, Patent Literature 1 discloses a polishing composition capable of quickly suppressing a polishing rate of a layer containing silicon-based materials other than polysilicon and selectively suppressing the polishing rate of a layer containing polysilicon. A polishing composition comprising colloidal silica particles having a zeta potential, a phosphoric acid or a specific organic phosphonic acid compound, and a specific anionic surfactant has been proposed.

Japanese Patent Laid-Open No. 2011-216581

However, even when using the composition described in the said patent document 1, it turned out that the selectivity of the silicon nitride with respect to polysilicon is not enough. It has also been found that it is difficult to increase the selectivity of silicon nitride to silicon oxide.

Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a polishing composition capable of polishing a polishing object containing silicon nitride with high selectivity to silicon oxide or polysilicon.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly researched in order to solve the said subject. As a result, it discovered that the said subject can be solved by using a predetermined additive, and completed this invention.

In other words, the above object,

At least 1 type of compound chosen from the group which consists of a compound represented by following formula (1), and its salt

It is achieved by a polishing composition comprising a.

(In formula (1), R <^1> is a substituted or unsubstituted C6-C30 hydrocarbon group, R <^2> is a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group, and X is a single bond or -CO-, Y is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent)

By using the polishing composition of the present invention, a polishing object containing silicon nitride can be polished with high selectivity to silicon oxide or polysilicon.

The polishing composition of the present invention,

At least 1 type of compound chosen from the group which consists of a compound represented by following formula (1), and its salt

It includes.

(In formula (1), R <^1> is a substituted or unsubstituted C6-C30 hydrocarbon group, R <^2> is a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group, and X is a single bond or -CO-, Y is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent)

According to the polishing composition having the above constitution, the polishing object including silicon nitride can be polished with high selectivity to silicon oxide or polysilicon.

The semiconductor wafer is composed of a dissimilar material such as silicon nitride to protect the silicon dioxide surface, which is not part of, for example, polycrystalline silicon forming a circuit, an insulating material silicon oxide, a trench or vias from etching. In such a patterned wafer, since the action of the polishing composition on each material is different, it is difficult to form a perfect flat surface, and it is required to reduce the level difference between different materials as much as possible.

One of the causes of the step is that a material which is relatively flexible and easily reacts with the abrasive, such as polycrystalline silicon or silicon oxide, is excessively cut compared to the surrounding silicon nitride or the like.

The polishing composition described in Patent Document 1 contains phosphoric acid or a specific organic phosphonic acid compound in addition to the abrasive. This phosphoric acid or a specific organic phosphonic acid compound acts as an accelerator for silicon nitride, so that the polishing rate of silicon nitride can be improved.

However, according to the examination of the present inventors, even if the polishing composition of Patent Document 1 is used, it is difficult to sufficiently increase the selectivity of silicon nitride to silicon oxide or polysilicon, and is currently required for polishing pattern wafers composed of different materials. Planarization cannot be achieved sufficiently. Therefore, further improvement is required.

In contrast, the present invention is characterized in that a predetermined compound having a long chain hydrocarbon group R ¹ and a carboxyl group (carboxylate) or a salt thereof is used as an additive. According to this configuration, since the polishing rate of the layer containing silicon oxide or polysilicon (a polishing object having a layer containing silicon oxide or polysilicon) can be suppressed, the layer containing silicon nitride at a relatively high rate It can be polished. Although the detailed mechanism which exhibits the said effect is unclear, it is thought that it is as follows. In addition, the following mechanism is a guess and does not limit the technical scope of this invention. In chemical mechanical polishing (CMP) of a layer containing silicon oxide or polysilicon, the use of a predetermined compound having a long-chain hydrocarbon group R ¹ and a carboxyl group (carboxylate) or a salt thereof as an additive includes silicon oxide and It was considered effective for suppressing the polishing rate of the layer containing polysilicon. In detail, the carboxyl group (carboxylate) side of the additive has a high chemical or physical adsorption force on the surface of the layer containing silicon oxide and polysilicon of the polishing object, and thus silicon oxide and poly A robust protective film can be formed on the surface of the layer containing silicon. Moreover, by having a long chain hydrocarbon group as R <^1> , it can suppress that the abrasive grain in a polishing composition contacts by the steric hindrance effect of a long chain hydrocarbon group. In addition, additives are adsorbed on the surface of the abrasive grains, and additives having steric hindrances are adsorbed on both the abrasive grains and silicon oxide or polysilicon, whereby contact between the abrasive grains and silicon oxide or polysilicon can be further suppressed. It is thought that the polishing of the surface of the layer containing silicon oxide and polysilicon by contact of an abrasive grain is suppressed by this.

Therefore, according to the polishing composition of the present invention, the layer containing silicon nitride can be polished at a high polishing rate while the polishing rate of the layer containing silicon oxide and polysilicon is kept low.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described. In addition, this invention is not limited only to the following embodiment.

In this specification, "X to Y" which shows a range means "X or more and Y or less." In addition, in this specification, unless it mentions specially, operation and measurement of a physical property etc. are performed on the conditions of room temperature (20-25 degreeC) / relative humidity 40-50% RH.

[Polishing object]

In the present invention, the polishing target is not particularly limited, and a polishing target having a metal or metal, a polishing target having an oxygen atom and a silicon atom, a polishing target having a silicon-silicon bond, a polishing target having a silicon-nitrogen bond, and the like Can be mentioned.

As a metal, tungsten, copper, aluminum, cobalt, hafnium, nickel, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, osmium, etc. are mentioned, for example.

As the object to be polished with an oxygen atom and a silicon atom, for example (hereinafter simply referred to as "TEOS"), silicon oxide (SiO _2), ortho-silicic acid tetraethyl (TEOS) oxide film obtained from the like.

Examples of the polishing object having a silicon-silicon bond include Si-based alloys such as polysilicon, amorphous silicon, single crystal silicon, n-type dope single crystal silicon, p-type dope single crystal silicon, and SiGe.

As a polishing object which has a silicon-nitrogen bond, the polishing object which has silicon-nitrogen bonds, such as a silicon nitride film and SiCN (silicon carbonitride), etc. are mentioned.

Since the polishing composition of the present invention has high selectivity with respect to a material having a silicon-nitrogen bond, especially silicon nitride, the polishing object preferably contains a material having a silicon-nitrogen bond, in particular silicon nitride.

In addition, the polishing composition of the present invention is preferably used for selectively polishing a material having a silicon-nitrogen bond in a polishing object including a material having a silicon-nitrogen bond and a material containing silicon. Can be. In particular, it can be used for the selective polishing of silicon nitride to polysilicon or silicon oxide.

Here, in the polishing composition according to one embodiment of the present invention, the lower limit of the ratio of the silicon nitride polishing rate (dl / min) to the silicon oxide polishing rate (dl / min) is preferably 28 or more, more preferably 30 or more. desirable. Moreover, it is preferable that it is 100 or less, and, as for the upper limit of the ratio of the silicon nitride polishing rate (k / min) with respect to the silicon oxide polishing rate (k / min), it is more preferable that it is 85 or less.

The lower limit of the ratio of the silicon nitride polishing rate to the polishing rate of polysilicon (Å / min) is preferably 7 or more, more preferably 10 or more, and even more preferably 14 or more. Moreover, it is preferable that it is 100 or less, and, as for the upper limit of the ratio of the silicon nitride polishing rate (k / min) with respect to the silicon oxide polishing rate (k / min), it is more preferable that it is 85 or less.

Moreover, as a product aspect, a grinding | polishing object has a preferable board | substrate, a semiconductor substrate is more preferable, and a pattern wafer is still more preferable.

[Polishing Composition]

The polishing composition of the present invention contains abrasive grains and predetermined additives. Hereinafter, the structure of the polishing composition of this invention is demonstrated.

(Grip)

The polishing composition of the present invention essentially contains abrasive grains. The abrasive grains contained in the polishing composition have a function of mechanically polishing the polishing object, thereby improving the polishing rate of the polishing object by the polishing composition.

The abrasive grains used may be any of inorganic particles, organic particles and organic inorganic composite particles. Specific examples of the inorganic particles include particles containing metal oxides such as silica, alumina, ceria, titania, silicon nitride particles, silicon carbide particles, and boron nitride particles. As a specific example of organic particle | grains, polymethyl methacrylate (PMMA) particle | grains are mentioned, for example. You may use these abrasive grains individually or in mixture of 2 or more types. In addition, the abrasive may use a commercial item or a synthetic product.

Among these abrasives, silica is preferred from the viewpoint of excellent dispersion stability, easy availability, and cost. If the abrasive is silica, the additive of formula (1) is likely to be adsorbed on the surface of the abrasive, and thus the effect of selectively polishing the silicon nitride film with respect to the silicon oxide film or polysilicon film can be further improved. Especially, colloidal silica is especially preferable.

The abrasive grains may be surface modified. In normal colloidal silica, since the value of the zeta potential is close to zero under acidic conditions, the silica particles tend to agglomerate without being electrically repulsed with each other under acidic conditions. In contrast, the abrasive grains surface-modified so that the zeta potential has a relatively large negative value even in acidic conditions strongly rebound against each other even under acidic conditions and are well dispersed. As a result, the storage stability of the polishing composition can be improved. Therefore, it is preferable to use abrasives surface-modified so that the zeta potential becomes negative at pH of the polishing composition, especially under acidic conditions. Such surface-modified abrasive grains can be obtained, for example, by mixing metals such as aluminum, titanium, zirconium, or oxides thereof with the abrasive grains and dope them to the surface of the abrasive grains.

Especially, especially preferable is silica which fixed the organic acid on the surface (it is also called organic modified silica and organic acid immobilized silica).

Although silica which immobilized the organic acid on the surface contains fumed silica, colloidal silica, etc., colloidal silica is especially preferable. Although the said organic acid is not specifically limited, Sulfonic acid, carboxylic acid, phosphoric acid, etc. are mentioned, Preferably it is sulfonic acid or carboxylic acid. In addition, on the surface of the silica which immobilized the organic acid contained in the polishing composition of the present invention on the surface, an acidic group derived from the organic acid (e.g., a sulfo group, a carboxyl group, a phosphoric acid group, etc.) (in some cases, has a linker structure). Through) covalent bonds.

The method of introducing these organic acids to the silica surface is not particularly limited, but for example, the organic acids may be introduced into the silica surface in a state such as a mercapto group or an alkyl group, and then oxidized to sulfonic acid or carboxylic acid. The acidic group derived from an organic acid is introduce | transduced into the silica surface in the state couple | bonded with the protecting group, After that, a method of detaching a protecting group is mentioned. In addition, the compound used when introducing an organic acid into the silica surface is not particularly limited, but has at least one functional group that can be an organic acid group, and is a functional group, hydrophobicity or hydrophilicity used for bonding to a hydroxyl group on the silica surface. It is preferable to include the functional group introduced for controlling, the functional group introduced for controlling the three-dimensional volume, and the like.

As a specific method for synthesizing silica in which an organic acid is immobilized on a surface, if sulfonic acid, which is one kind of organic acid, is immobilized on a silica surface, for example, "Sulfonic acid-functionalized silica through quantitative oxidation of thiolgroups", Chem. Commun. This can be done by the method described in 246-247 (2003). Specifically, after coupling a silane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxysilane to silica and oxidizing the thiol group with hydrogen peroxide, a silica in which sulfonic acid is immobilized on the surface can be obtained. Alternatively, if the carboxylic acid is immobilized on the surface of silica, for example, "Novel Silane Coupling Agents Containing a Photolabile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel", Chemistry Letters, 3, 228- This can be done by the method described in 229 (2000). Specifically, by coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to silica and then irradiating with light, silica having a carboxylic acid immobilized on its surface can be obtained.

The average degree of association of the abrasive grains is also less than 5.0, for example, more preferably 3.0 or less, still more preferably 2.5 or less. As the average association degree of the abrasive grains becomes small, the surface roughness caused by the shape of the abrasive grains can be made good. It is preferable that the average association degree of an abrasive grain is 1.0 or more, More preferably, it is 1.05 or more. This average association degree is obtained by dividing the value of the average secondary particle diameter of an abrasive grain by the value of an average primary particle diameter. As the average degree of association of the abrasive grains increases, there is an advantageous effect that the polishing rate of the object to be polished by the polishing composition is improved.

It is preferable that it is 5 nm or more, and, as for the minimum of the average primary particle diameter of an abrasive grain, it is more preferable that it is 10 nm or more. Moreover, it is preferable that the upper limit of the average primary particle diameter of an abrasive grain is 200 nm or less, It is more preferable that it is 150 nm or less, It is further more preferable that it is 100 nm or less. Within such a range, the polishing rate of the polishing object by the polishing composition can be improved, and the occurrence of surface defects on the surface of the polishing object after polishing using the polishing composition can be further suppressed. In addition, the average primary particle diameter of an abrasive grain is computed based on the specific surface area of the abrasive grain measured by the BET method, for example.

It is preferable that the minimum of the average secondary particle diameter of an abrasive grain is 15 nm or more, It is more preferable that it is 20 nm or more, It is further more preferable that it is 30 nm or more. Moreover, it is preferable that the upper limit of the average secondary particle diameter of an abrasive grain is 300 nm or less, It is more preferable that it is 260 nm or less, It is further more preferable that it is 220 nm or less. Within such a range, the polishing rate of the polishing object by the polishing composition can be improved, and the occurrence of surface defects on the surface of the polishing object after polishing using the polishing composition can be further suppressed. In addition, the secondary particle here means the particle | grains formed by the abrasive grains being aggregated in the polishing composition, and the average secondary particle diameter of this secondary particle can be measured by the dynamic light scattering method, for example.

The upper limit of the aspect ratio of the abrasive grain in the polishing composition is, for example, less than 2.0, preferably 1.8 or less, and more preferably 1.5 or less. If it is such a range, the surface roughness caused by the shape of an abrasive grain can be made favorable. The aspect ratio is an average of values obtained by taking a minimum rectangle circumscribed to the image of the abrasive grain by a scanning electron microscope, and dividing the length of the long side of the rectangle by the length of the short side of the same rectangle. You can get it using the software. The minimum of the aspect ratio of the abrasive grain in a polishing composition is 1.0 or more. The closer to this value, the better the surface roughness caused by the shape of the abrasive grain can be.

Particle diameter (D90) and total particle weight of all particles when the accumulated particle weight reaches 90% of the total particle weight in the particle size distribution determined by the laser diffraction scattering method in the abrasive grain in the polishing composition. The lower limit of D90 / D10, which is the ratio of the particle diameter (D10) when it reaches 10% of, is, for example, 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more. Further, in the particle size distribution obtained by the laser diffraction scattering method in the abrasive grain in the polishing composition, the particle diameter (D90) and the total of all the particles when the accumulated particle weight reaches 90% of the total particle weight from the fine particle side. The upper limit of the ratio D90 / D10 of the particle diameter (D10) when it reaches 10% of the particle weight is not particularly limited, but is preferably 2.04 or less. If it is such a range, the surface roughness caused by the shape of an abrasive grain can be made favorable.

It is preferable that the lower limit of content of the abrasive grain in a polishing composition is 0.0005 mass% or more, More preferably, it is 0.001 mass% or more, More preferably, it is 0.005 mass% or more, More preferably, it is 0.01 mass% or more, Especially preferably, It is 0.1 mass% or more. As the content of the abrasive grains increases, the polishing rate of the object to be polished by the polishing composition is further improved. It is preferable that content of the abrasive grain in a polishing composition is 5 mass% or less, More preferably, it is 3 mass% or less, More preferably, it is 1 mass% or less, More preferably, it is 0.5 mass% or less, Especially preferable Preferably it is 0.3 mass% or less. Within this range, the silicon nitride can be more selectively polished. Moreover, since erosion to a stopper film can be suppressed, it is preferable. Moreover, the cost of a polishing composition can be suppressed, and generation | occurrence | production of a surface defect on the surface of the polishing object after grinding | polishing using a polishing composition can be suppressed more.

(mountain)

In order to adjust the pH of a polishing composition to a desired value, it is preferable that the polishing composition of this invention contains an acid. In addition, in this specification, the compound represented by Formula (1) as an additive, or its salt is handled as what differs from the acid as a pH adjuster.

The acid is not particularly limited and may be any of an inorganic acid and an organic acid. Examples of the organic acid include formic acid, caproic acid, enanthic acid, caprylic acid, pelagonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. , Arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid, isophthalic acid, terephthalic acid, gallic acid, melitric acid, cinnamic acid, fumaric acid, maleic acid, aconitic acid, nitrocarboxylic acid, citric acid, succinic acid, malonic acid, Tartaric acid, lactic acid, malic acid, acetic acid, phthalic acid, glycolic acid, crotonic acid, valeric acid, 2-hydroxybutyric acid, γ-hydroxybutyric acid, 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid, glycerinic acid, benzoic acid, Leucine, propionic acid, butyric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid , 2-ethylhexanoic acid, salicylic acid, oxalic acid, glutaric acid, adipic acid, blood Carboxylic acids such as melic acid and mandelic acid, and sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, isetionic acid and taurine. In addition, inorganic acids, such as carbonic acid, hydrochloric acid, nitric acid, phosphoric acid, hypophosphorous acid, phosphorous acid, phosphonic acid, sulfuric acid, boric acid, hydrofluoric acid, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, and hexamethic acid, are mentioned. These acids can be used individually or in mixture of 2 or more types.

The amount of the acid added is not particularly limited, and the amount of acid may be appropriately selected to fall within the desired pH range.

The acids may be used alone or in the form of a mixture of two or more thereof.

The content of the acid in the polishing composition is not particularly limited, but is preferably an amount such that the pH of the polishing composition is 1 or more and less than 5. Such a polishing composition for pH is excellent in storage stability. Moreover, the handling of the polishing composition is easy. In addition, the polishing rate of the polishing object can be improved.

(additive)

An additive adsorb | sucks on the surface of a polysilicon film or a silicon oxide film, and acts to suppress these surface grinding | polishing rates by suppressing contact of an abrasive grain by a steric hindrance effect. The polishing composition of the present invention contains a compound represented by the following formula (1) or a salt thereof.

In formula (1), R <^1> is a substituted or unsubstituted C6-C30 hydrocarbon group, R <^2> is a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group, X is a single bond or- CO- and Y is a C1-C30 bivalent hydrocarbon group which may have a substituent.

When the carbon number of R ¹ is 5 or less, since the effect of steric hindrance due to R ¹ is hardly obtained on the surface of the polishing object including the silicon oxide film or the polysilicon film, it is easily in contact with the abrasive grains and easily polished. do. As a result, high selectivity in polishing the silicon nitride film is not obtained. On the other hand, since the water solubility will fall when carbon number of R <^1> exceeds 30, the dispersion stability of the compound of Formula (1) or its salt may fall. Preferably, as carbon number of R <^1> , it is 6 or more and 22 or less, More preferably, it is 10 or more and 20 or less, Especially preferably, it is 12 or more and 18 or less.

Although it does not restrict | limit especially as a hydrocarbon group, Alkyl group, an alkenyl group, an alkadienyl group, an alcatenyl group, an alkynyl group, a cycloalkyl group, an aryl group, etc. are used, Preferably it is an alkyl group or an alkenyl group.

The alkyl group may be linear or branched, and may be hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl or hexadecyl ( Cetyl group), heptadecyl group, octadecyl group (stearyl group), nonadecyl group, isicosyl group, eicosyl group, hencosyl group, hencosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexa A kosyl group, a heptacosyl group, an octacosyl group, a nonacosyl group, an isohexyl group, 2-ethylhexyl group, etc. are mentioned. Especially, a linear thing can be used preferably. Among these, a decyl group, an undecyl group, a dodecyl group, and a heptadecyl group are preferable, and a dodecyl group and a heptadecyl group are more preferable.

As an alkenyl group, for example, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl Group, heptadecenyl group, octadecenyl group, octadecatenyl group, (5Z, 8Z, 11Z, 14Z) -nonadeca-5,8,11,14-tetraenyl group, isocenyl group, henicosenyl A group, a docosenyl group, a triacontenyl group, etc. are mentioned. Especially, a linear thing can be used preferably. Among these, nonenyl group, decenyl group, undecenyl group, dodecenyl group, and heptadecenyl group are preferable.

Examples of the alkadienyl group include hexadienyl group, heptadienyl group, octadienyl group, 1-ethylpentadienyl group, 2-methylpentadienyl group, and the like.

As an alcatrienyl group, a hexatrienyl group, a heptatrienyl group, an octatrienyl group, a 1-methylhexatrienyl group, 2-methylhexatrienyl group, etc. are mentioned, for example.

Although it does not restrict | limit especially as a substituent, A halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), a hydroxyl group, a nitro group, a carbonyl group, etc. are mentioned.

In Formula (1), R <^2> is a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group. Examples of the substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group and iso Pentyl group, tert-pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, isohexyl group, 2-ethylhexyl group, etc. are mentioned. Preferably, R <^2> is a hydrogen atom, a C1-C10 linear or branched alkyl group, More preferably, it is a hydrogen atom, a C1-C3 alkyl group, Especially preferably, it is a hydrogen atom or a methyl group. As the substituent for R ^2, the same substituents as those described above for R ¹ can be used.

Y is a C1-C30 bivalent hydrocarbon group which may have a substituent. As a substituent, the thing similar to the above can be used.

Preferably, Y is a C1-C4 alkylene group or group represented by following formula (2). With the above configuration, the effects of the present invention can be obtained more remarkably.

In Formula (2), Z is a C1-C3 alkylene group. As a C1-C3 alkylene group, a methylene group, ethylene group, n-propylene group, etc. are mentioned, for example. Preferably, Z is a methylene group or an ethylene group. The alkylene group having 1 to 3 carbon atoms may have a substituent, and those similar to the above may be used as the substituent.

Although it does not restrict | limit especially as a salt of the compound represented by said Formula (1), The salt of group 2 elements, such as alkali metal salts, such as a sodium salt and potassium salt, calcium salt, an amine salt, an ammonium salt, etc. are mentioned. Of these, sodium salts are preferred.

As a specific example of a compound represented by said Formula (1), or its salt, N-oleoyl sarcosine, N-lauroyl sarcosine, N-oleoyl glutamic acid, N-lauroyl glutamic acid, N-oleoyl aspartic acid, N-lauroyl aspartic acid, N-oleoyl-N-methylalanine, N-lauroyl-N-methylalanine, and these salts are mentioned.

The compound represented by the said Formula (1) or its salt may be used individually by 1 type, and may be used in combination of 2 or more type.

Content (concentration) of the compound represented by the said Formula (1) which is an additive in a polishing composition, or its salt is not specifically limited. For example, it is preferable that the minimum of content (concentration) of the said addition is 0.0001 mass% or more with respect to the final polishing composition, It is more preferable that it is 0.0001 mass% or more, It is further more preferable that it is 0.001 mass% or more. Within this range, the polishing rate of the silicon oxide film or the polysilicon film can be suppressed, and polishing objects having silicon-nitrogen bonds such as silicon nitride films can be selectively polished. In addition, deterioration of surface conditions such as surface roughness of the polishing surface can be suppressed. Moreover, it is preferable that it is 1 mass% or less with respect to the final polishing composition, and, as for the upper limit of content (concentration) of the said additive, it is more preferable that it is 0.1 mass% or less. If it is this range, the outstanding polishing rate of the polishing object which has silicon-nitrogen bonds, such as a silicon nitride film, can be obtained. Moreover, it is suitable from the viewpoint of storage stability and cost. When using the compound represented by said formula (1) or its salt in combination of 2 or more types, it is preferable that the sum total content is the said range.

(Dispersion medium)

It is preferable that the polishing composition of this invention contains a dispersion medium in order to disperse | distribute or melt | dissolve each component. Here, the dispersion medium is not particularly limited, but water is preferable. From the viewpoint of inhibiting the action of other components, water that does not contain impurities as much as possible is more preferable. Specifically, after removing the impurity ions with an ion exchange resin, the pure water or ultrapure water from which the foreign material is removed through a filter, Or distilled water is preferred.

(pH)

The polishing composition according to one embodiment of the present invention contains a dispersion medium, and the pH of the polishing composition is preferably 1 or more and less than 5. Such a polishing composition for pH is excellent in storage stability. Moreover, the handling of the polishing composition is easy. When the pH of the polishing composition is less than 5, the positive charge on the surface of the polishing object becomes small, and when the surface of the polishing object is used with negatively charged abrasive grains (for example, silica having an organic acid immobilized on the surface), It becomes easy to grind. From the viewpoint of polishing the polishing object by the polishing composition at a sufficient polishing rate, the pH of the polishing composition is more preferably 4 or less, particularly preferably 3 or less. It is preferable that the minimum of the pH value of a polishing composition is 1 or more from a viewpoint of safety, More preferably, it is 1.5 or more.

(Other ingredients)

The polishing composition according to one embodiment of the present invention may be a complexing agent, a preservative, other than the compound represented by the formula (1) or a salt thereof, if necessary, in addition to the compound represented by the formula (1) or the salt thereof, which are abrasive grains and additives; You may contain other components, such as an antifungal agent, a reducing agent, surfactant, and a water-soluble polymer. The complexing agent, the preservative, the fungus inhibitor, the reducing agent, the surfactant, and the water-soluble polymer are not particularly limited, and known ones used in the fields of the polishing composition can be used. However, on the other hand, it is preferable that the polishing composition which concerns on this invention does not contain an oxidizing agent substantially. When the oxidizing agent is contained in the polishing composition, the composition is supplied to a silicon film or the like as the polishing object, whereby the surface of the polishing object is oxidized to form an oxide film, which can be scraped off by abrasive grains, thereby reducing the polishing selectivity. The oxidizing agent herein can promote the formation of an oxide film on the surface of the silicon film, and specific examples of the oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, sodium persulfate, potassium persulfate and persulfate Ammonium, potassium persulfate, oxone, sodium dichloroisocyanurate, and the like. In addition, the fact that a polishing composition does not contain an oxidizing agent substantially does not contain an oxidizing agent at least intentionally. Therefore, a small amount (e.g., a molar concentration of the oxidizing agent in the polishing composition is 0.0005 mol / L or less, preferably 0.0001 mol or less, more preferably 0.00001 mol / L or less, especially from a raw material or a manufacturing method, Preferably, the polishing composition in which an oxidizing agent of 0.000001 mol / L or less) is inevitably included may be included in the concept of the polishing composition that does not substantially contain the oxidizing agent as mentioned herein.

In addition, the polishing composition of the present invention does not substantially contain the di-quaternary compound described, for example, in JP-A-2013-42131. Moreover, it is preferable that the polishing composition of this invention does not contain substantially the iodine compound (for example, potassium iodide) which may be a trigger of iodine gas generation | occurrence | production. Specifically, it is preferable that content of the said compound is 10 mass% or less (lower limit: 0 mass%) with respect to a polishing composition, and it is more preferable that it is 5 mass% or less (lower limit: 0 mass%).

Moreover, as an additive other than the additive which is a compound represented by said Formula (1), or its salt, especially in order to improve the grinding | polishing rate of a silicon nitride film with respect to a silicon oxide film or a polysilicon film, an abrasive grain surface in a polishing composition. When it is negatively charged, it is preferable not to include what has a sulfo group. The sulfo group may be dissociated and ionized in a dispersion medium such as water and adsorbed on the surface of the positively charged silicon nitride film to cause a negative transition. At this time, both the surface of the abrasive grain and the surface of the silicon nitride film are negatively charged, whereby the polishing rate of the silicon nitride film may decrease.

[Manufacturing Method of Composition for Polishing]

The method for producing the polishing composition of the present invention is not particularly limited, and for example, an abrasive, a predetermined additive, and an acid, an oxidizing agent, and other additives are mixed, if necessary, preferably a dispersion medium (for example, water). It can obtain by stirring mixing in the inside. The detail of each component is as above-mentioned. Therefore, this invention provides the manufacturing method of the polishing composition of this invention containing mixing the said abrasive grain and the said predetermined additive.

Although the temperature at the time of mixing each component is not specifically limited, 10-40 degreeC is preferable and you may heat in order to raise a dissolution rate. In addition, the mixing time is not particularly limited as long as it is uniformly mixed.

[Polishing Method and Manufacturing Method of Substrate]

As described above, the polishing composition of the present invention is suitably used for polishing a layer (polishing object) containing silicon nitride. Therefore, the present invention also provides a polishing method for polishing a polishing object having a layer containing silicon nitride with the polishing composition of the present invention. Moreover, this invention provides the manufacturing method of the board | substrate which includes the process of grinding | polishing the layer (polish object) containing silicon nitride by the said grinding | polishing method.

As a polishing apparatus, the holder which holds the board | substrate etc. which have a to-be-polishing object, the motor etc. which can change a rotation speed, etc. are provided, and the general polishing apparatus which has a polishing plate which can attach a polishing pad (polishing cloth) can be used.

As the polishing pad, a general nonwoven fabric, polyurethane, porous fluororesin, or the like can be used without particular limitation. It is preferable that the polishing pad is subjected to groove processing in which the polishing liquid is accumulated.

About grinding | polishing conditions, 10-500 rpm of the rotational speed of a grinding | polishing plate, for example is preferable. The pressure (polishing pressure) applied to the substrate having the polishing object is preferably 0.5 to 10 psi. The method for supplying the polishing composition to the polishing pad is also not particularly limited, and for example, a method for continuously supplying with a pump or the like is employed. Although this supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

After the completion of polishing, the substrate is washed in running water and the water droplets adhered to the substrate by a spin dryer or the like are dried to obtain a substrate having a layer containing silicon nitride.

The polishing composition of the present invention may be a one-part type or a multi-part type including a two-part type. In addition, the polishing composition of the present invention may be prepared by diluting the stock solution of the polishing composition to 10 times or more using diluent such as water.

<Example>

This invention is demonstrated in more detail using the following example and a comparative example. However, the technical scope of the present invention is not limited only to the following examples. In addition, "%" and "part" mean "mass%" and a "mass part", respectively, unless there is particular notice. In addition, in the following Example, unless otherwise specified, operation was performed on the conditions of room temperature (25 degreeC) / relative humidity 40-50% RH.

Example 1

(Preparation of the composition for polishing)

In pure water, 0.01 mass% of N-oleoyl sarcosine with respect to the final polishing composition, maleic acid with 0.35 mass% with respect to the final polishing composition, and abrasive grains (sulfonic acid immobilized colloidal silica; average primary particle diameter: 14 nm, average 2 Difference particle diameter: 40 nm) The polishing composition was prepared by adding in an amount of 0.25% by mass relative to the final polishing composition. It was 1.9 when the pH of the polishing composition (liquid temperature: 25 ° C) was confirmed by a pH meter (manufactured by Horiba, Ltd., model number: LAQUA).

[Examples 2 to 5 and Comparative Examples 1 to 5]

(Preparation of the composition for polishing)

Except having changed the kind and content of each component as shown in following Table 1, it operated like Example 1, and prepared the polishing compositions of each Example and a comparative example.

About each polishing composition obtained above, the removal rate (m / min) was evaluated by the following method. The results are shown in Table 1 together.

<Polishing Test>

(Polishing device and polishing condition)

In Examples 1-5 and Comparative Examples 1-5, using each polishing composition, the surface of the polishing object was polished under the following conditions. As the polishing object, a silicon wafer having a diameter of 200 mm was formed on the surface of which a SiN film (silicon nitride film) having a thickness of 2500 mm, a silicon oxide film obtained from TEOS of 10000 mm, or a polysilicon film of 4000 mm 3 was formed.

Polishing device: single-sided CMP grinder for 200 mm wafers (mirra from Applied Materials)

Pad: Supreme RN-H (Dow Chemical Co., Ltd.)

Polishing pressure: 2psi

Rotational Speed of Polishing Table: 93rpm

Carrier Rotation Speed: 87rpm

Supply amount of the polishing composition: 150 mL / min

Polishing time: 60 sec.

Ex-situ dressing 15s.

<Measurement of Removal Rate>

The polishing rate (polishing rate) (dl / min) was calculated by the following formula (1).

Film thicknesses of silicon oxide (SiN), polysilicon (poly-Si), and silicon oxide obtained from TEOS were determined by an optical interference film thickness measuring apparatus, and evaluated by dividing the difference in film thickness before and after polishing by polishing time.

According to the results of Table 1 above, by using the polishing compositions of Examples 1 to 5 containing the specific additives, the silicon nitride film was polished at a high speed as compared with Comparative Examples 1 to 5, and the silicon oxide film and the polysilicon film were The polishing rate can be suppressed.

As in Comparative Example 1, when the additive does not have a long-chain hydrocarbon group or when it does not have an amino group as in Comparative Examples 3 to 5, the effect of selectively polishing the silicon nitride film with respect to the silicon oxide film or the polysilicon film is sufficiently sufficient. Not obtained. In addition, when the additive contains a sulfo group as in Comparative Example 4, the sulfo group is dissociated and ionized in water, adsorbed on the surface of the positively charged silicon nitride film, and transferred to the negative. It is considered that the polishing rate of the silicon nitride film is not expressed by negative charging of both the abrasive grain and the silicon nitride film. In addition, polysilicon and silicon oxide are also considered to have no selectivity because the polishing rate is similarly suppressed.

Claims (12)

Abrasive grain,
At least 1 type of compound chosen from the group which consists of a compound represented by following formula (1), and its salt
A polishing composition comprising a.

(In formula (1), R <^1> is a substituted or unsubstituted C6-C30 hydrocarbon group, R <^2> is a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group, and X is a single bond or -CO-, Y is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent) The method of claim 1,
Y in said Formula (1) is a C1-C4 alkylene group, or is a group represented by following formula (2), The polishing composition.

(In formula (2), Z is a C1-C3 alkylene group which may have a substituent.) The method according to claim 1 or 2,
R <^1> in the said Formula (1) is a polishing composition which is a substituted or unsubstituted C6-C22 hydrocarbon group. The method according to any one of claims 1 to 3,
R <^2> in said Formula (1) is a polishing composition which is a C1-C3 alkyl group. The method according to any one of claims 1 to 4,
Polishing composition, wherein the abrasive is silica. The method of claim 5,
A polishing composition, wherein the abrasive is an organic acid immobilized silica. The method according to any one of claims 1 to 6,
The polishing composition further comprising a dispersion medium and having a pH of 1 to 5. The method according to any one of claims 1 to 7,
A polishing composition for use in the selective polishing of silicon nitride to polysilicon or silicon oxide. The method according to any one of claims 1 to 8,
A polishing composition comprising substantially no oxidizing agent. The abrasive for polishing according to any one of claims 1 to 9, comprising mixing the abrasive with at least one compound selected from the group consisting of a compound represented by the formula (1) and a salt thereof. Method of Preparation of the Composition. A polishing method comprising polishing a polishing object having a layer containing silicon nitride using the polishing composition according to any one of claims 1 to 9. The manufacturing method of the board | substrate which includes grinding | polishing the grinding | polishing object which has a layer containing silicon nitride by the grinding | polishing method of Claim 11.