TW201940646A - Polishing composition capable of polishing a polishing object containing silicon nitride with high selectivity - Google Patents

Abstract

An object of the present invention is to provide a polishing composition capable of polishing a polishing object containing silicon nitride with high selectivity compared to silicon oxide or polysilicon. A polishing composition provided in the present invention which comprises abrasive grains and at least one compound selected from the group consisting of a compound represented by the following formula (1) and a salt thereof. (In formula (1), R1 is a substituted or unsubstituted hydrocarbon group having 6 to 30 carbon atoms, and R2 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 divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.).

Description

Polishing composition

The present invention relates to a polishing composition.

In recent years, due to the high accumulation of miniaturization of LSI manufacturing processes, electronic devices such as computers have gradually achieved high performance such as miniaturization, multifunctionalization, and high speed. A new microfabrication technology accompanying the advancement of such LSIs is the use of a chemical mechanical polishing (CMP) method. The CMP method is a technique frequently used in LSI manufacturing steps. In particular, the CMP method uses planarization of an interlayer insulating film in a multilayer wiring formation step, formation of metal plugs, and formation of buried wiring (dashed wiring).

CMP is gradually applied to each step of semiconductor manufacturing. As one aspect, for example, it can be applied to the gate formation step of transistor manufacturing.

In the manufacture of transistors, there are cases where Si-containing materials such as polycrystalline silicon (polycrystalline silicon), silicon oxide, and silicon nitride are polished, and it is required to be able to control the polishing rate of each Si-containing material. For example, as a polishing composition in which the polishing rate of a layer containing a silicon-based material other than polycrystalline silicon is fast and can selectively suppress the polishing rate of a layer containing polycrystalline silicon, Patent Document 1 proposes a gel containing a negative zeta potential. A polishing composition for colloidal silica particles, phosphoric acid or a specific organic phosphonic acid compound, and a specific anionic surfactant.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2011-216581

[Questions to be Solved by the Invention]

However, it has been found that even when the composition described in Patent Document 1 is used, the selectivity of silicon nitride to polycrystalline silicon is still insufficient. Furthermore, it has been known that it is difficult to increase the selectivity of silicon nitride over 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 silicon nitride-containing polishing object at a higher selectivity than silicon oxide or polycrystalline silicon.
[Means to solve the problem]

In order to understand the above-mentioned problems, the present inventors have conducted intensive studies. As a result, it was found that the above-mentioned problems can be solved by using a predetermined additive, and the present invention has been completed.

That is, the above object can be achieved by a polishing composition containing abrasive particles and at least one compound selected from the group consisting of a compound represented by the following formula (1) and a salt thereof,

(In the formula (1), R ¹ is a substituted or unsubstituted hydrocarbon group having 6 or more and 30 carbon atoms, R ² is a hydrogen atom, or a substituted or unsubstituted hydrocarbon group having 1 or more and 30 carbon atoms, and X is mono A bond or -CO-, Y is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent).
[Inventive effect]

By using the polishing composition of the present invention, a silicon nitride-containing polishing object can be polished with a higher selectivity than silicon oxide or polycrystalline silicon.

[Forms for Implementing Invention]

The polishing composition of the present invention contains abrasive particles and at least one compound selected from the group consisting of a compound represented by the following formula (1) and a salt thereof.

(In the formula (1), R ¹ is a substituted or unsubstituted hydrocarbon group having 6 or more and 30 carbon atoms, R ² is a hydrogen atom, or a substituted or unsubstituted hydrocarbon group having 1 or more and 30 carbon atoms, and X is mono A bond or -CO-, Y is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent).
When the polishing composition having the above-mentioned configuration is used, a silicon nitride-containing polishing object can be polished with a higher selectivity than silicon oxide or polycrystalline silicon.

Semiconductor wafers are made of heterogeneous materials such as polycrystalline silicon that forms circuits, silicon oxide that is an insulating material, and silicon dioxide surfaces that are not part of a trench or via to protect it from etching. Damaged silicon nitride. In such a patterned wafer, since the polishing composition has different effects on each material, it is difficult to form a completely flat surface, and it is required to reduce the step difference between different materials as much as possible.

As one of the causes of the step difference, the following cases may be mentioned: materials such as polycrystalline silicon and silicon oxide which are relatively soft and easily react with abrasives are excessively cut off compared to surrounding silicon nitride and the like.

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

However, according to the study by the present inventors, even if the polishing composition of Patent Document 1 is used, it is difficult to sufficiently improve the selectivity of silicon nitride with respect to silicon oxide or polycrystalline silicon, and it has not been possible to sufficiently achieve the current use of heterogeneous materials. The polishing of the patterned wafer is required to be planarized. 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. With this configuration, since the polishing rate of a layer containing silicon oxide or polycrystalline silicon (an object to be polished having a layer containing silicon oxide or polycrystalline silicon) can be suppressed, the layer containing silicon nitride can be polished at a relatively high speed. Although a detailed mechanism for achieving the above effect is not clear, it is considered as follows. The following mechanisms are speculative and do not limit the technical scope of the present invention. In chemical mechanical polishing (CMP) of a layer containing silicon oxide or polycrystalline silicon, it is considered 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 to suppress the layer containing silicon oxide and polycrystalline silicon. The grinding speed is effective. Specifically, since the carboxyl (carboxylate) side of the additive has a high chemical or physical adsorption force on the surface of the silicon oxide and polycrystalline silicon-containing layer of the object to be polished, the carboxyl (carboxylate) A strong protective film is formed on the surface of the silicon oxide and polycrystalline silicon layers. In addition, by having a long-chain hydrocarbon group as R ¹ , the use of the steric hindrance effect of the long-chain hydrocarbon group can suppress the contact of the abrasive particles in the polishing composition. In addition, the additive is similarly adsorbed on the surface of the abrasive grains, and the additive having a three-dimensional obstacle is adsorbed on both the abrasive grains and the silicon oxide or polycrystalline silicon, so that the contact between the abrasive grains and the silicon oxide or polycrystalline silicon can be further suppressed. It is thought that this can suppress polishing of the surface of the layer containing silicon oxide and polycrystalline silicon due to the contact of the abrasive particles.

Therefore, when the polishing composition of the present invention is used, the polishing rate of the layer containing silicon oxide and polycrystalline silicon is suppressed to be low, and at the same time, the layer containing silicon nitride can be polished at a higher polishing rate.

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

In this specification, "X to Y" indicating a range means "above X and below Y". In addition, in this specification, unless otherwise stated, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C) and relative humidity of 40 to 50 RH%.

[Object to be polished]
In the present invention, the object to be polished is not particularly limited, and examples thereof include a metal or a metal-containing layer, an object to be polished having an oxygen atom and a silicon atom, an object to be polished having a silicon-silicon bond, and an abrasive having a silicon-nitrogen bond. Objects, etc.

Examples of the metal include tungsten, copper, aluminum, cobalt, osmium, nickel, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, and osmium.

Examples of the object to be polished having an oxygen atom and a silicon atom include, for example, silicon oxide (SiO ₂ ) and a silicon oxide film (hereinafter simply referred to as “TEOS”) obtained from tetraethyl orthosilicate (TEOS). Wait.

Examples of polishing objects having silicon-silicon bonds include polycrystalline silicon, amorphous silicon, single crystal silicon, n-type doped single crystal silicon, p-type doped single crystal silicon, and silicon germanium (SiGe). Si-based alloys and the like.

Examples of the object to be polished having a silicon-nitrogen bond include a silicon-nitrogen film and a polishing object having a silicon-nitrogen bond, such as SiCN (silicon carbonitride).

The polishing composition of the present invention has a high selectivity for a material having a silicon-nitrogen bond, especially for silicon nitride. Therefore, a material to be polished is preferably a material having a silicon-nitrogen bond, and especially contains nitrogen. Silicon is better.

In addition, the polishing composition of the present invention can be suitably used for selectively polishing a material having a silicon-nitrogen bond in a material to be polished having a silicon-nitrogen bond and other silicon-containing materials. In particular, it can be used for selective polishing of silicon nitride over polycrystalline silicon or silicon oxide.

Here, the lower limit of the ratio of the polishing rate (Å / min) of silicon nitride to the polishing rate (Å / min) of silicon oxide in one form of the polishing composition of the present invention is preferably 28 or more, and 30 The above is better. The upper limit of the ratio of the polishing rate (Å / min) of silicon nitride to the polishing rate (Å / min) of silicon oxide is preferably 100 or less, and more preferably 85 or less.

The lower limit of the ratio of the polishing rate (Å / min) of silicon nitride to the polishing rate (Å / min) of polycrystalline silicon is preferably 7 or more, more preferably 10 or more, and even more preferably 14 or more. The upper limit of the ratio of the polishing rate (Å / min) of silicon nitride to the polishing rate (Å / min) of silicon oxide is preferably 100 or less, and more preferably 85 or less.

In addition, as the object of polishing, a substrate is preferred, a semiconductor substrate is preferred, and a pattern wafer is further preferred.

[Polishing composition]
The polishing composition of the present invention contains abrasive particles and a predetermined additive. The structure of the polishing composition of the present invention will be described below.

(Abrasive particles)
The polishing composition of the present invention must contain abrasive particles. The abrasive grains contained in the polishing composition have the function of mechanically polishing the object to be polished, and also increase the polishing rate of the polishing composition to the object to be polished.

The abrasive particles used may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include, for example, particles composed of metal oxides such as silica, alumina, ceria, and titanium oxide, silicon nitride particles, and carbonization. Silicon particles, boron nitride particles. Specific examples of the organic particles include, for example, polymethyl methacrylate (PMMA) particles. These abrasive grains can be used individually or in mixture of 2 or more types. As the abrasive grains, a commercially available product or a synthetic product can be used.

Among these abrasive particles, silicon oxide is preferred from the viewpoints of excellent dispersion stability, easy availability, and cost. In addition, when the abrasive particles are silicon oxide, the additive of the formula (1) is easily adsorbed on the surface of the abrasive particles, which can further improve the effect of selectively polishing the silicon nitride film relative to the silicon oxide film, polycrystalline silicon film, and the like. Better. Colloidal silica is particularly preferred.

The abrasive particles can also be surface modified. Because the colloidal silicon oxide usually has a zeta potential value close to zero under acidic conditions, under acidic conditions, the silicon oxide particles are not electrically repelled from each other and easily aggregate. In contrast, the abrasive particles that have been surface-modified so that the Zeta potential also has a large negative value under acidic conditions strongly repel each other and disperse well even under acidic conditions. As a result, the storage stability of the polishing composition can be improved. Therefore, it is preferred that the polishing particles are surface-modified so that the pH of the polishing composition becomes negative, particularly under acidic conditions, using a Zeta potential. Such surface-modified abrasive particles can be obtained by, for example, mixing a metal such as aluminum, titanium, or zirconium or an oxide thereof with the abrasive particles, and doping the surface of the abrasive particles.

Particularly preferred is silicon oxide (also referred to as organically modified silicon oxide, organic acid-immobilized silicon oxide) formed by fixing an organic acid on the surface.

The silicon oxide formed by fixing an organic acid on the surface includes fumed silica, colloidal silica, and the like, and colloidal silica is particularly preferred. The organic acid is not particularly limited, and examples thereof include sulfonic acid, carboxylic acid, and phosphoric acid, and sulfonic acid or carboxylic acid is preferred. In addition, the surface of the silicon oxide in which the organic acid is fixed on the surface contained in the polishing composition of the present invention is an acidic group derived from the organic acid (for example, a sulfo group, a carboxyl group, a phosphate group, etc.) It is immobilized by a covalent bond (through a linker structure as appropriate).

The method of introducing these organic acids onto the surface of silicon oxide is not particularly limited. For example, a method of introducing the organic acid onto the surface of silicon oxide in the state of a mercapto group, an alkyl group, or the like, and then oxidizing it to a sulfonic acid or a carboxylic acid. A method may also be mentioned in which the protective group is bonded to the surface of the silicon oxide in a state where the protective group is bonded to the acidic group derived from the organic acid, and then the protective group is detached. The compound used when introducing an organic acid onto the surface of silicon oxide is not particularly limited, and it contains at least one functional group capable of becoming an organic acid group, and further contains a functional group capable of being used for bonding to a hydroxyl group on the surface of silicon oxide Functional groups introduced to control the hydrophobicity and hydrophilicity, and functional groups introduced to control the height of the three-dimensional volume are preferred.

As a specific synthetic method of silicon oxide obtained by immobilizing an organic acid on a surface, when a sulfonic acid, which is a kind of organic acid, is immobilized on the surface of silicon oxide, for example, "Sulfonic acid-functionalized silica through quantitative oxidation of thiolgroups" can be used. (Silica functionalized with sulfonic acid by quantitative oxidation of thiol group) ", Chem Commun. Chem. 246-247 (2003). Specifically, after silane coupling agent having a thiol group, such as 3-mercaptopropyltrimethoxysilane, is used to couple silicon oxide, the thiol group is oxidized with hydrogen peroxide, whereby the sulfonic acid can be immobilized. Silicon oxide formed on the surface. Or when the carboxylic acid is immobilized on the surface of silicon oxide, for example, "Novel Silane Coupling Agents Containing a Photolabile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel (containing photoreactive 2-nitrate The novel silane coupling agent of benzyl ester is used to introduce a carboxyl group on the surface of silicone rubber ", Chemistry Letters, 3,228-229 (2000). Specifically, after coupling silicon dioxide with a silane coupling agent containing a photoreactive 2-nitrobenzyl ester, a silicon oxide obtained by immobilizing a carboxylic acid on the surface can be obtained by irradiating light.

The average degree of association of the abrasive grains is, for example, less than 5.0, preferably 3.0 or less, and more preferably 2.5 or less. As the average degree of association of the abrasive grains becomes smaller, the surface roughness due to the shape of the abrasive grains can be made better. The average degree of association of the abrasive grains is preferably 1.0 or more, and more preferably 1.05 or more. The average degree of association can be obtained by dividing the value of the average secondary particle diameter of the abrasive grains by the value of the average primary particle diameter. As the average degree of association of the abrasive particles becomes larger, there is an advantageous effect of increasing the polishing rate of the polishing composition on the object to be polished.

The lower limit of the average primary particle diameter of the abrasive grains is preferably 5 nm or more, and more preferably 10 nm or more. The upper limit of the average primary particle diameter of the abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. Within this range, the polishing rate of the polishing composition with respect to the object to be polished can be increased, and further, it is possible to further suppress occurrence of surface defects on the surface of the object to be polished after polishing using the polishing composition. The average primary particle diameter of the abrasive particles can be calculated, for example, based on the specific surface area of the abrasive particles measured by the BET method.

The lower limit of the average secondary particle diameter of the abrasive particles is preferably 15 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. The upper limit of the average secondary particle diameter of the abrasive particles is preferably 300 nm or less, more preferably 260 nm or less, and still more preferably 220 nm or less. Within such a range, the polishing rate of the polishing composition with respect to the object to be polished can be increased, and further, it is possible to further suppress the occurrence of surface defects on the surface of the object to be polished after polishing using the polishing composition. The secondary particles herein refer to particles obtained by associating abrasive particles with the polishing composition. The average secondary particle diameter of the secondary particles can be measured using, for example, a dynamic light scattering method.

The upper limit of the aspect ratio of the abrasive particles 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 this range, the surface roughness by the shape of an abrasive grain can be made favorable. The aspect ratio can be obtained by using a scanning electron microscope to obtain the smallest rectangle of the image of the external abrasive particles, and dividing the long side length of the rectangle by the short side length of the same rectangle. Image analysis software. The lower limit of the aspect ratio of the abrasive particles in the polishing composition is 1.0 or more. The closer to this value, the better the surface roughness due to the shape of the abrasive grains.

The particle size distribution of the abrasive particles in the polishing composition obtained by using laser diffraction scattering method, from the cumulative particle weight of the particle side to the diameter (D90) of the particles when reaching 90% of the total particle weight and the total particles reached The ratio of the diameter (D10) of the particles at 10% of the total particle weight, that is, the lower limit of D90 / D10, for example, is 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more. In addition, the particle size distribution of the abrasive particles in the polishing composition obtained by laser diffraction scattering method is from the cumulative particle weight on the particle side to the diameter (D90) and the particle diameter of the particle when it reaches 90% of the total particle weight. The ratio of the diameter (D10) of the particles at 10% of the total particle weight of the whole particles, that is, the upper limit of D90 / D10 is not particularly limited, but is preferably 2.04 or less. If it is this range, the surface roughness by the shape of an abrasive grain can be made favorable.

The lower limit value of the content of the abrasive particles in the polishing composition is preferably 0.0005 mass% or more, more preferably 0.001 mass% or more, still more preferably 0.005 mass% or more, and still more preferably 0.01 mass% or more. Particularly preferred is 0.1% by mass or more. As the content of the abrasive particles increases, the polishing rate of the polishing composition with respect to the object to be polished is further increased. The content of the abrasive particles in the polishing composition is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.3. Mass% or less. Within this range, silicon nitride can be further selectively polished. In addition, it is preferable because the erosion of the stop film can be suppressed. In addition, it is possible to suppress the cost of the polishing composition and further suppress the occurrence of surface defects on the surface of the object to be polished after polishing using the polishing composition.

(acid)
In order to adjust the pH of the polishing composition to a desired value, the polishing composition of the present invention preferably contains an acid. In the present specification, the compound represented by formula (1) or a salt thereof as an additive is treated differently from an 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, hexanoic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid. Acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid ( eicosapentaenoic acid), isophthalic acid, terephthalic acid, gallic acid, pyromellitic 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, glyceric acid, benzoic acid, leucine, propionic acid, butyric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylvaleric acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, salicylic acid, oxalic acid, glutaric acid, adipic acid, heptane Carboxylic acids such as acids, picroic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, 2-isethionic acid, taurine acid. In addition, carbonic acid, hydrochloric acid, nitric acid, phosphoric acid, hypophosphorous acid, phosphorous acid, phosphoric acid, sulfuric acid, boric acid, hydrofluoric acid, orthophosphoric acid, coke Inorganic acids such as phosphoric acid, polyphosphoric acid, metaphosphoric acid, and hexametaphosphoric acid. These acids can be used individually or in mixture of 2 or more types.

The amount of the acid to be added is not particularly limited, and the amount of the acid to be added may be appropriately selected so as to achieve a desired pH range.

These acids can be used alone or in the form of a mixture of two or more.

The content of the acid in the polishing composition is not particularly limited, and it is preferred that the pH of the polishing composition be 1 or more and less than 5. Such a polishing composition at pH has excellent storage stability. The polishing composition is easy to handle. In addition, the polishing speed of the object to be polished can be increased.

(additive)
Additives, while adsorbing on the surface of polycrystalline silicon film, silicon oxide film, etc., suppress the contact of the abrasive particles by the steric obstacle effect, and have the effect of inhibiting the polishing speed of these surfaces. 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 hydrocarbon group having 6 or more and 30 carbon atoms, R ² is a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 or more and 30 carbon atoms, and X is a single bond Or -CO-, Y is a divalent hydrocarbon group having 1 or more and 30 or less carbons which may have a substituent.

When the carbon number of R ¹ is 5 or less, the surface of an object to be polished containing a silicon oxide film or a polycrystalline silicon film does not easily obtain the effect of a three-dimensional obstacle caused by R ¹ , so it is easy to contact the abrasive grains and be easily polished. As a result, a high selectivity cannot be obtained in polishing a silicon nitride film. On the other hand, when the carbon number of R ¹ is more than 30, the stability of the dispersion of the compound of the formula (1) or a salt thereof may be lowered because the water solubility is lowered. The carbon number of R ¹ is preferably 6 or more and 22 or less, more preferably 10 or more and 20 or less, and particularly preferably 12 or more and 18 or less.

The hydrocarbon group is not particularly limited, and an alkyl group, an alkenyl group, an alkadienyl group, an alkatrienyl group, an alkynyl group, a cycloalkyl group, or an aryl group can be used, and an alkyl group or an alkenyl group is preferred. .

The alkyl group may be linear or branched, and examples include hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, and tetradecyl , Fifteen, sixteen (cetyl), seventeen, eighteen (stearyl), nineteen, icosyl, eicosyl, twenty-one (henicosyl), twenty-one (heneicosyl), twenty-two, twenty-three, twenty-four, twenty-five, twenty-six, twenty-seven, twenty-nine Group, isohexyl, 2-ethylhexyl and the like. In particular, a linear thing can be suitably used. Among these, decyl, eleven, twelve, and seventeen are preferred, and twelve. Seventeen bases are preferred.

Examples of the alkenyl group include hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, Pentadecenyl, hexadecenyl, heptenyl, octadecenyl, octadecatrienyl, (5Z, 8Z, 11Z, 14Z) -nonadecan-5, 8, 11, 14-tetraenyl, eicosenyl, icosenyl, docosenyl, docosenyl, and the like. In particular, a linear thing can be suitably used. Among these, nonenyl, decenyl, undecenyl, dodecenyl, and heptenyl are preferred.

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

Examples of the alkyltrienyl group include hexatrienyl, heptadienyl, octatrienyl, 1-methylhexatrienyl, and 2-methylhexatrienyl.

The substituent is not particularly limited, and examples thereof include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), a hydroxyl group, a nitro group, and a carbonyl group.

In the formula (1), R ² is a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms. Examples of the substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, and tertiary Butyl, pentyl, isopentyl, tertiary pentyl, neopentyl, hexyl, heptyl, octyl, isohexyl, 2-ethylhexyl and the like. R ^{2 is} preferably a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, particularly preferably a hydrogen atom or a methyl group. base. Moreover, as a substituent group R ² can be used as described above has exemplified the substituents R ^1, the same thing.

Y is a divalent hydrocarbon group which may have a carbon number of 1 or more and 30 or less. As a substituent, the thing similar to the above can be used.

Y is preferably an alkylene group having 1 to 4 carbon atoms, or a group represented by the following formula (2). If it is the said structure, the effect of this invention can be acquired more remarkable.

In the formula (2), Z is an alkylene group having 1 to 3 carbon atoms. Examples of the alkylene group having 1 to 3 carbon atoms include, for example, methylene, ethylidene, and n-propylidene. Preferably, Z is methylene or ethylene. The above-mentioned alkylene having 1 to 3 carbon atoms may have a substituent, and as the substituent, the same thing as described above can be used.

The salt of the compound represented by the formula (1) is not particularly limited, and examples thereof include alkali metal salts such as sodium salts and potassium salts, salts of Group 2 elements such as calcium salts, amine salts, and ammonium salts. Among these, sodium salt is preferred.

Specific examples of the compound represented by the above formula (1) or a salt thereof include N-oleyl sarcosinate, N-lauroyl sarcosinate, N-oleyl glutamate, and N-laurate Glutamic acid, N-oleyl aspartic acid, N-lauryl aspartic acid, N-oleyl-N-methylalanine, N-lauryl-N-methylalanine 2. Salts of these compounds.

The compound represented by the formula (1) or a salt thereof may be used singly or in combination of two or more kinds.

The content (concentration) of the additive in the polishing composition, that is, the compound represented by the formula (1) or a salt thereof is not particularly limited. For example, the lower limit of the content (concentration) added is preferably 0.0001% by mass or more, more preferably 0.0001% by mass or more, and even more preferably 0.001% by mass or more relative to the final polishing composition. Within such a range, the polishing rate of a silicon oxide film, a polycrystalline silicon film, and the like can be suppressed, and a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be selectively polished. Further, it is possible to suppress deterioration of the surface state such as the surface roughness of the polished surface. The upper limit of the content (concentration) of the additive is preferably 1% by mass or less, and more preferably 0.1% by mass or less with respect to the final polishing composition. Within this range, an excellent polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be obtained. Furthermore, it is preferable from the viewpoint of preservation stability and cost. When the compound represented by the formula (1) or a salt thereof is used in combination of two or more kinds, the total content is preferably in the above range.

(Dispersion medium)
In order to disperse or dissolve each component, the polishing composition of the present invention preferably contains a dispersion medium. Here, the dispersion medium is not particularly limited, and water is preferred. From the standpoint of suppressing the effects of impeding other components, it is preferable to use water that does not contain impurities as much as possible. Specifically, pure water after removing impurities by using an ion exchange resin and then removing foreign matter through a filter , Ultrapure water, etc., or distilled water is preferred.

(pH)
The polishing composition according to one aspect 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 at pH has excellent storage stability. Moreover, the polishing composition is easy to handle. When the pH of the polishing composition is less than 5, the positive charge on the surface of the object to be polished becomes small. When using abrasive particles with a negatively charged surface (for example, silicon oxide obtained by fixing an organic acid to the surface), it is easy to increase the speed. Polish the object to be polished. From the viewpoint of using the polishing composition and polishing the object to be polished at a sufficient polishing rate, the pH of the polishing composition is more preferably 4 or less, particularly preferably 3 or less. From the viewpoint of safety, the lower limit of the pH value of the polishing composition is preferably 1 or more, and more preferably 1.5 or more.

(Other ingredients)
In addition to the abrasive grains and additives, that is, the compound for polishing according to one aspect of the present invention, that is, the compound represented by formula (1) or a salt thereof, the composition for polishing according to the present invention may contain an error other than the compound represented by formula (1) or a salt thereof as necessary. Mixtures, preservatives, antifungal agents, reducing agents, surfactants, water-soluble polymers and other ingredients. The complexing agent, preservative, antifungal agent, reducing agent, surfactant, and water-soluble polymer are not particularly limited, and conventional materials used in the field of polishing compositions can be used. However, on the other hand, it is preferable that the polishing composition of the present invention does not substantially contain an oxidizing agent. When an oxidizing agent is contained in the polishing composition, the composition is supplied to a silicon film or the like as an object to be polished, and the surface of the object to be polished is oxidized to form an oxide film. The oxide film may be scraped off by the abrasive particles. As a result, the polishing selection ratio is low. The oxidant herein refers to a substance that can promote the formation of an oxide film on the surface of a silicon film. Specific examples of the oxidant include hydrogen peroxide (H ₂ O ₂ ), hydrogen peroxide, peracetic acid, percarbonate, and peroxide. Urea, sodium persulfate, potassium persulfate, ammonium persulfate, potassium monopersulfate, potassium monopersulfate (OXONE), sodium dichloroisocyanurate, and the like. The polishing composition does not substantially contain an oxidant, and means that the oxidant is not intentionally contained at least. Therefore, trace amounts derived from raw materials, production methods, etc. (for example, the molar concentration of the oxidizing agent in the polishing composition is 0.0005 mol / L or less, preferably 0.0001 mol / L or less, preferably 0.00001 Moore / L or less, particularly preferably 0.00001 Moore / L or less) A polishing composition for an oxidizing agent can be included in the concept of a polishing composition that does not substantially contain an oxidizing agent.

The polishing composition of the present invention does not substantially contain, for example, a second (quaternary) compound described in Japanese Patent Application Laid-Open No. 2013-42131. Moreover, it is preferable that the polishing composition of the present invention does not substantially contain an iodine compound (for example, potassium iodate) that may be a trigger for generating iodine gas. Specifically, the content of the compound is preferably 10% by mass or less (lower limit: 0% by mass) relative to the polishing composition, and more preferably 5% by mass or less (lower limit: 0% by mass).

In addition, as an additive other than the compound of the compound represented by the above formula (1) or a salt thereof, particularly as a substance for improving the polishing rate of a silicon nitride film with respect to a silicon oxide film or a polycrystalline silicon film, in a polishing composition When the surface of the abrasive particles is negatively charged, it is better not to contain substances having a sulfo group. The sulfo group is dissociated and ionized in a dispersion medium such as water, and may be adsorbed on the surface of the positively-charged silicon nitride film and made it negatively charged. At this time, since both the surface of the abrasive grain and the surface of the silicon nitride film are negatively charged, the polishing rate of the silicon nitride film may be reduced.

[Manufacturing method of polishing composition]
The method for producing the polishing composition of the present invention is not particularly limited. For example, it is possible to mix abrasive particles, predetermined additives, and optionally an acid, an oxidizing agent, and other additives. Obtained by stirring. The details of each component are as described above. Therefore, this invention provides the manufacturing method of the polishing composition of this invention which contains the said abrasive grain and the said predetermined additive.

The temperature at which the components are mixed is not particularly limited, and is preferably 10 to 40 ° C. Heating can also be performed to increase the dissolution rate. 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 can be suitably used for polishing a silicon nitride-containing layer (object to be polished). Therefore, the present invention also provides a polishing method for polishing a polishing object of a silicon nitride-containing layer using the polishing composition of the present invention. The present invention also provides a method for manufacturing a substrate, which includes a step of polishing a silicon nitride-containing layer (object to be polished) using the aforementioned polishing method.

As the polishing device, a general polishing device can be used, which is equipped with a holder that holds a substrate having an object to be polished, a motor that can change the number of rotations, and the like, and has a polishing dial capable of attaching a polishing pad (polishing cloth).

The polishing pad is not particularly limited, and ordinary nonwoven fabrics, polyurethanes, porous fluororesins, and the like can be used. The polishing pad is preferably groove-processed by storing a polishing liquid.

For the grinding conditions, for example, the rotation speed of the grinding turntable is preferably 10 to 500 rpm. The pressure (polishing pressure) applied to the substrate having the object to be polished is preferably 0.5 to 10 psi. The method for supplying the polishing composition to the polishing pad is also not particularly limited, and for example, a method of continuously supplying a pump or the like can be adopted. The supply amount is not limited, and it is preferred that the polishing composition of the present invention be used to cover the surface of the polishing pad.

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

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

The present invention will be described in more detail using the following examples and comparative examples, but the technical scope of the present invention is not limited by the following examples. In addition, unless otherwise noted, "%" and "part" each mean "mass%" and "mass part". In the following examples, unless otherwise specified, the operation was performed under the conditions of room temperature (25 ° C) and relative humidity of 40 to 50 RH%.

[Example 1]
(Preparation of polishing composition)
By adding to pure water: N-oleyl sarcosinic acid in an amount of 0.01% by mass relative to the final polishing composition and 0.35% by mass of cis-butene in the final polishing composition Diacid, and abrasive particles (sulfonic acid-immobilized colloidal silica; average primary particle size: 14 nm, average secondary particle size: 40 nm) in an amount of 0.25% by mass based on the final polishing composition to adjust polishing With the composition. The pH of the polishing composition (liquid temperature: 25 ° C) was confirmed to be 1.9 using a pH meter (model: LAQUA, manufactured by Horiba, Ltd.).

[Examples 2 to 5 and Comparative Examples 1 to 5]
(Preparation of polishing composition)
A polishing composition for each example and comparative example was prepared in the same manner as in Example 1 except that the types and contents of each component were changed as shown in Tables 1 to 3 below.

About each polishing composition obtained above, the polishing rate (Removal Rate) (Å / min) was evaluated by the following method. The results are shown in Table 1 below.

＜ Grinding test ＞
(Grinding device and grinding conditions)
In Examples 1 to 5 and Comparative Examples 1 to 5, each polishing composition was used to polish the surface of an object to be polished under the following conditions. As the object to be polished, a silicon wafer having a diameter of 200 mm having a SiN film (silicon nitride film) having a thickness of 2500 Å, a silicon oxide film obtained from TEOS at 10,000 Å, or a polycrystalline silicon film having a thickness of 4000 Å was used.

Polishing device: single-sided CMP polisher (Mirra, manufactured by Applied Materials) for 200 mm wafers
Gasket: Supreme RN-H (manufactured by Dow Chemical)
Grinding pressure: 2psi
Rotation speed of grinding turntable: 93rpm
Carrier rotation speed: 87rpm
Supply amount of the polishing composition: 150 mL / min
Grinding time: 60sec.

EX-situ dressing: 15s.

<Measurement of Removal Rate>
The polishing rate (polishing rate) (A / min) is calculated in accordance with the following formula (1).

[Number 1]
Formula 1):

The film thickness of silicon nitride (SiN), polycrystalline silicon (poly-Si), and silicon oxide obtained from TEOS was determined using an optical interference film thickness measuring device, and the difference in film thickness before and after polishing was divided by the polishing time To evaluate.

[Table 1]

According to the results in Table 1 above, by using the polishing compositions of Examples 1 to 5 containing specific additives, compared to Comparative Examples 1 to 5, the silicon nitride film can be polished at a high speed and the silicon oxide film and the polycrystalline silicon film can be suppressed. Grinding speed.

As in Comparative Example 1, when the additive does not have a long-chain hydrocarbon group, or when Comparative Examples 3 to 5 do not have an amine group, compared to a silicon oxide film, a polycrystalline silicon film, etc., a selective polishing of a silicon nitride film cannot be sufficiently obtained. effect. In addition, as in Comparative Example 4, when the additive system contains a sulfo group, the sulfo group dissociates and ionizes in water and adsorbs on the surface of the positively-charged silicon nitride film to make it negatively charged. It is considered that the polishing rate of the silicon nitride film is not significant because both the abrasive particles and the silicon nitride film are negatively charged. In addition, it is considered that the polishing rate of polycrystalline silicon and silicon oxide is similarly suppressed and selectivity cannot be obtained.

no.

no.

Claims (12)

A polishing composition comprising abrasive particles and at least one compound selected from the group consisting of a compound represented by the following formula (1) and a salt thereof, (In the formula (1), R ¹ is a substituted or unsubstituted hydrocarbon group having 6 or more and 30 carbon atoms, R ² is a hydrogen atom, or a substituted or unsubstituted hydrocarbon group having 1 or more and 30 carbon atoms, and X is mono A bond or -CO-, Y is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent). The polishing composition according to item 1 of the scope of patent application, wherein Y in the aforementioned formula (1) is an alkylene group having 1 or more and 4 or less carbon atoms, or a group represented by the following formula (2), (In the formula (2), Z is an alkylene group having 1 to 3 carbon atoms which may have a substituent.) The polishing composition as described in claim 1 or 2, wherein R ¹ in the aforementioned formula (1) is a substituted or unsubstituted hydrocarbon group having 6 or more and 22 or less carbon atoms. The polishing composition according to any one of claims 1 to 3, wherein R ² in the aforementioned formula (1) is an alkyl group having 1 to 3 carbon atoms. The polishing composition according to any one of claims 1 to 4, wherein the abrasive particles are silicon oxide. The polishing composition according to item 5 of the scope of patent application, wherein the abrasive particles are organic acid-immobilized silica. The polishing composition according to any one of claims 1 to 6 of the patent application range further contains a dispersion medium, and has a pH of 1 or more and less than 5. The polishing composition according to any one of claims 1 to 7 of the scope of patent application, used for selective polishing of silicon nitride with respect to polycrystalline silicon or silicon oxide. The polishing composition according to any one of claims 1 to 8 of the scope of application for a patent, which does not substantially contain an oxidizing agent. A method for producing a polishing composition, which is the method for producing a polishing composition according to any one of claims 1 to 9 of the scope of application for a patent, comprising the aforesaid abrasive grains and the formula (1) At least one compound of the group consisting of the compound and its salt is mixed. A polishing method includes polishing an object to be polished having a silicon nitride-containing layer using the polishing composition according to any one of claims 1 to 9 of the scope of patent application. A method for manufacturing a substrate includes polishing an object to be polished having a silicon nitride-containing layer by using the polishing method described in Patent Application Scope 11.