JP2016157913A - Polishing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing composition which can sufficiently suppress the polishing rate for an object to be polished having a silicon-nitrogen bond, such as a silicon nitride film, in at least one of acidic, neutral, and basic ranges.SOLUTION: There is provided a polishing composition which comprises (1) an organic compound having an active site that interacts with an object to be polished having a silicon-nitrogen bond, and a suppression site that suppresses the approach of a polishing constituent for polishing the object to be polished toward the object to be polished, and (2) abrasive particles, the polishing composition suppressing the polishing rate for an object to be polished having the silicon-nitrogen bond in at least one of acidic, neutral, and basic ranges.SELECTED DRAWING: None

Description

  The present invention relates to a polishing composition.

  2. Description of the Related Art Conventionally, a new fine processing technology has been developed along with the high integration and high performance of LSI (Large Scale Integration). Chemical mechanical polishing (hereinafter also referred to as chemical mechanical polishing; simply referred to as CMP) is one of them. LSI manufacturing processes, particularly shallow trench isolation (STI), planarization of an interlayer insulating film (ILD film), formation of tungsten plugs, CMP is used in processes such as the formation of multilayer wiring composed of copper and a low dielectric constant film.

  In such a semiconductor device manufacturing process, there is a demand for polishing a polishing object such as polysilicon, silicon nitride, or a composite material thereof at high speed.

  On the other hand, depending on the structure of the semiconductor device, it is required to suppress the polishing rate of each Si-containing material, and for that purpose, an attempt is made to improve the selection ratio.

  When improving the polishing rate of other film types in order to improve the selection ratio, the particle diameter, shape and concentration of the abrasive grains are generally improved by surface modification with a coupling agent or the like. There are methods for improving the polishing rate by changing the zeta potential. Thus, in this industry, examination of how to improve the polishing rate has been made.

  However, in the case of this method, the present inventor has found that even when the selection ratio is improved, the removal rate of the film to be suppressed may be slightly increased.

  On the other hand, in the industry, a method for suppressing the polishing rate of the other material has not been sufficiently studied. As a method for suppressing the polishing rate of the other few materials, polyacrylic acid, a strong acid having a pKa of 3 or less, and a strong base having a pKa of 10 or more are contained as additives for suppressing the removal rate of the silicon nitride film. However, there is an example in which an additive for abrasives having a pH of 6.5 to 8.0 is used (Patent Document 1).

  However, the technique disclosed in Patent Document 1 cannot sufficiently control the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film, and further improvement has been desired.

JP 2008-182179 A

  As described above, the present inventor has recognized that when the polishing rate of other film types is improved in order to improve the selection ratio, the removal rate of the film to be suppressed may be slightly increased.

  In such a case, not only the semiconductor transistor structure is not finished as designed, but there is a possibility that the electrical characteristics and the reliability of the device are lowered due to the change in the height of the device. For these reasons, it is necessary to suppress polishing of an unintended layer.

  Therefore, an object of the present invention is to provide a polishing composition capable of sufficiently suppressing the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film.

  This inventor repeated earnest research in order to solve the said subject. As a result, (1) an action site that interacts with a polishing object having a silicon-nitrogen bond, and a suppression part that suppresses a polishing component that polishes the polishing object from approaching the polishing object; (2) Abrasive grains having at least one region of acidic, neutral or basic, and for suppressing polishing of the polishing object having a silicon-nitrogen bond. It has been found that the above problems can be solved by providing a composition.

  According to the present invention, there is provided a polishing composition capable of sufficiently controlling the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film in at least one of acidic, neutral and basic regions. Can be provided.

  The present invention will be described below. In addition, this invention is not limited only to the following embodiment. In this specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50% RH.

<Polishing composition>
The present invention includes (1) an action site that interacts with a polishing object having a silicon-nitrogen bond, and a suppression part that suppresses a polishing component that polishes the polishing object from approaching the polishing object; (2) Abrasive grains having at least one region of acidic, neutral or basic, and suppressing polishing rate of the polishing object having a silicon-nitrogen bond. Composition. In the present specification, such “polishing composition” is also referred to as “polishing composition of the present invention”.

[Organic compounds]
As described above, the organic compound of the present invention polishes the polishing object with an action site that interacts with a polishing object having a silicon-nitrogen bond (also simply referred to as “polishing object” in the present specification). A polishing component that suppresses the approach of the polishing component to the polishing object (also referred to as “organic compound of the present invention” in the present specification).

  The organic compound of the present invention contains a low-molecular compound, and the low-molecular compound has an action site that interacts with a polishing object having a silicon-nitrogen bond in one molecule, and a polishing component that polishes the polishing object. However, it has simultaneously the suppression site | part which suppresses approaching the said grinding | polishing target object. Further, the organic compound of the present invention includes a polymer, and the polymer has the action site and the suppression site simultaneously in one molecule, and preferably has a structure constituting the polymer. The unit has the action site and the suppression site at the same time. Therefore, the site of action in the organic compound interacts with the object to be polished, and on the other hand, the suppression site prevents the polishing component that polishes the object to be polished from approaching the object to be polished. Therefore, a polishing composition containing such an organic compound sufficiently suppresses the polishing rate of a polishing object having a silicon-nitrogen bond, such as a silicon nitride film, in at least one of acidic, neutral, and basic regions. To do. In other words, a compound that does not have an action site and a suppression site simultaneously in one molecule is distinguished from the organic compound of the present invention.

  Further, in the present specification, "suppressing the polishing rate of the polishing object having a silicon-nitrogen bond in at least one region of acidic, neutral or basic" as shown in the examples, A polishing object having a silicon-nitrogen bond such as a silicon nitride film in any region as compared with the case where no additives (that is, components other than “abrasive grains, dispersion medium, and pH adjuster as necessary”) are added at all. This means that the polishing rate is suppressed.

  In the present specification, the “polishing component” is a component capable of polishing an object to be polished, and means, for example, abrasive grains.

(Action site)
As described above, the organic compound of the present invention has an action site that interacts with a polishing object having a silicon-nitrogen bond. Here, the “action site” may have any structure as long as it is a site that interacts with a polishing object having a silicon-nitrogen bond, but preferably an oxygen atom, a sulfur atom, and phosphorus. At least one selected from the group consisting of atoms. By having such a structure, it is possible to interact with a polishing object having a silicon-nitrogen bond. The action site may be in the form of a salt, and a sodium salt, potassium salt, ammonium salt, amine salt or the like is preferable as the salt.

  Specifically, the site of action includes a sulfide group, a sulfonic acid group or a salt group thereof (including an aromatic sulfonic acid structure), an amino group, a phosphonic acid group or a salt group thereof, a nitrile group, a carboxyl group or a group thereof. It is at least one selected from the group consisting of a salt group (including an aromatic carboxylic acid structure (benzoic acid structure)), a phenyl group, a pyridyl group, an ammonium group, a sulfate group or a salt group thereof, and a betaine structure. By having such a structure, the polishing object having a silicon-nitrogen bond can surely interact.

  In a preferred embodiment of the present invention, the action site has at least one of a nitrogen atom and an oxygen atom. By having such a structure, the polishing object having a silicon-nitrogen bond can surely interact.

  Among these, the pKa of the action site is preferably 12 or less, more preferably 10 or less, and further preferably 6 or less, from the viewpoint of interaction with the polishing object having a silicon-nitrogen bond. .

  Moreover, in the preferable form of this invention, as pKa of an action site, Preferably it is 5 or less, More preferably, it is 4 or less, More preferably, it is 3 or less, Most preferably, it is 2 or less. An action site having a pKa of 5 or less can even more reliably interact with a polishing object having a silicon-nitrogen bond. Examples of such an action site having a pKa of 5 or less include a sulfonic acid group or a salt group thereof, a phosphonic acid group or a salt group thereof, a carboxyl group or a salt group thereof, and the like. In addition, pKa of an action site is pKa Data Compiled by R.P. Values described in Williams (http://research.chem.psu.edu/brpgroup/pKa_complication.pdf) are adopted.

  The organic compound of the present invention has at least one action site, preferably two or more, in one molecule of a low molecular compound. The polymer of the present invention has at least two action sites in one molecule of the polymer. By having two or more action sites, the polishing object having a silicon-nitrogen bond can reliably interact. Examples of the organic compound having two or more action sites include disodium dodecyl diphenyl ether disulfonate, disodium lauryl sulfosuccinate, sodium polystyrene sulfonate, and the like.

  As the number of action sites in one molecule of the polymer, a value calculated by the following calculation formula can be used when the polymer is composed only of structural units having an action site and a suppression site at the same time. In addition, the weight average molecular weight of a polymer can be measured by the method as described in an Example.

(Suppression site)
In addition, as described above, the organic compound of the present invention has a suppression site for suppressing the polishing component that polishes the polishing object from approaching the polishing object. Here, the “suppressed part” may have any structure as long as the polishing component for polishing the polishing object has an action of suppressing the approach to the polishing object. The number of suppression sites is not particularly limited as long as it is 1 or more per molecule, and may be 2 or more.

  In one embodiment of the present invention, the organic compound of the present invention is a low molecular compound, and the suppression sites in one molecule are preferably sites having 3 or more carbon atoms in total. In one embodiment of the present invention, the suppression sites have a total of 4 or more carbon atoms. In one embodiment of the present invention, the suppression sites have a total of 6 or more carbon atoms. In one embodiment of the present invention, the suppression sites have a total of 8 or more carbon atoms. In particular, when the total number of carbon atoms is 3 or more, it is easy to produce a self-alignment film that is a suppression film by suppressing a decrease in the hydrophobicity of the suppression site. Moreover, since the approach of the grinding | polishing component with respect to a grinding | polishing target object (substrate surface) is suppressed more as carbon number is 3 or more in total, the suppression effect is improved.

  Here, “total” means that, for example, when the organic compound is “laurylphosphonic acid”, the “action site” is “phosphonic acid group” and the “suppression site” is “lauryl group”. The carbon number of the “part” is 12. Further, when the organic compound is “N, N-dimethyl-n-octylamine”, there is “amino group” as “action site”, one “octyl group” as “inhibition site”, “methyl group” Since there are two, the total number of carbon atoms of the “suppression site” is 10.

  On the other hand, in one embodiment of the present invention, the organic compound of the present invention is a low molecular compound, and the suppression sites in one molecule have a total of 20 or less carbon atoms. On the other hand, in one embodiment of the present invention, the suppression sites have a total of 18 or less carbon atoms. On the other hand, in one embodiment of the present invention, the suppression sites have a total of 16 or less carbon atoms. If the organic chain (carbon number) at the suppression site is too large, the solubility in the slurry (polishing composition) will be low, so that a sufficient amount of the inhibitor (organic compound of the present invention) can be added. There is a risk of disappearing. In addition, if the organic chain becomes too long, the suppression site tends to bend (a state where it is bent not in a straight line), and the density of the suppression film and the generation rate of the self-aligned film decrease, resulting in a suppression effect. There is also a risk of lowering.

  According to one embodiment of the present invention, the organic compound of the present invention is a low molecular compound, and the suppression site in one molecule is a site having an alkyl group having 1 or more carbon atoms. According to one embodiment of the present invention, the suppression site is a site having an alkyl group having 4 or more carbon atoms. According to one embodiment of the present invention, the suppression site is a site having an alkyl group having 7 or more carbon atoms.

  According to the preferable form of this invention, the organic compound of this invention is a low molecular compound, and the suppression site | part in 1 molecule is a site | part which has a C8 or more alkyl group. As described above, when the alkyl group is significantly long, the polishing component for polishing the object to be polished has the action of suppressing the approach to the object to be polished more reliably.

  On the other hand, even if an organic compound is a low-molecular compound and has such a significantly long alkyl group in one molecule, an action site that interacts with an object to be polished having a silicon-nitrogen bond. If not, the interaction of the organic compound with a polishing object having a silicon-nitrogen bond such as a silicon nitride film cannot be sufficiently controlled. In other words, even if such an organic compound is contained in the polishing composition, it is a polishing object having a silicon-nitrogen bond such as a silicon nitride film of an organic compound in at least one of an acidic, neutral or basic region. The effect of sufficiently controlling the interaction with things cannot be expected. Thus, the organic compound of the present invention is important in that the action site and the suppression site coexist in one molecule.

  According to a more preferred embodiment of the present invention, the organic compound of the present invention is a low molecular compound, and the suppression site in one molecule is a site having an alkyl group having 11 or more carbon atoms. According to this, the said suppression site | part is a site | part which has a C12 or more alkyl group. According to a preferred embodiment of the present invention, the suppression site is a site having an alkyl group having 20 or less carbon atoms. According to a more preferred embodiment of the present invention, the suppression site is an alkyl group having 18 or less carbon atoms. According to a more preferred embodiment of the present invention, the suppression site is a site having an alkyl group having 16 or less carbon atoms.

  When the organic compound of the present invention is a low molecular weight compound, if the number of carbons of the suppression site in one molecule is 3 or more, a decrease in hydrophobicity of the suppression site is suppressed, and a molecular arrangement film that is a suppression film is prepared. It becomes easy. Moreover, since the approach of the grinding | polishing component with respect to a grinding | polishing target object (board | substrate surface) is more easily suppressed as carbon number is 3 or more, the suppression effect is improved. However, if the organic chain (carbon number) at the suppression site is too large, the solubility in the slurry will be low, and there is a risk that it will not be possible to add an amount of the inhibitor (organic compound of the present invention) sufficient to suppress it. . In addition, if the organic chain becomes too long, the suppression site tends to bend (a state where it is bent not in a straight line), and the density of the suppression film and the generation rate of the molecular arrangement film decrease, resulting in a suppression effect. There is also a risk of lowering.

  Thus, by setting the optimal organic chain length, a dense molecular arrangement film can be formed, and the approach of the polishing component can be suppressed.

  The alkyl group may be linear or branched. However, in the case of a branched group, the number of organic molecules that can act on the same area may decrease (the density of organic molecules decreases). For this reason, there is a possibility that the suppression ability is reduced. Moreover, in the case of a branched alkyl group, it is considered that the self-alignment rate of the suppression film composed of an organic compound having a suppression site is reduced due to the complexity of the structure. Therefore, it is preferably linear.

  Specific examples of the alkyl group having 1 to 20 carbon atoms are not particularly limited, but are methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl. Group, isopentyl group, neopentyl group, 2-ethylhexyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group (myristyl group), heptadecyl group, octadecyl group ( Stearyl group), nonadecyl group, icosyl group and the like. Further, there may be a partially unsaturated bond such as an oleyl group, or a behenyl group which is an alkyl group having 20 or more carbon atoms. Moreover, the alkyl group in the organic compound used in the Example can also be mentioned as a suitable example.

  Moreover, according to the preferable form of this invention, the organic compound of this invention is a low molecular compound, and the number of the C4 or more alkyl groups as a suppression site | part in 1 molecule is 1-3. In view of ease of self-arrangement of an organic compound having a suppression site, it is more preferably one. According to a more preferred embodiment of the present invention, the organic compound of the present invention is a low molecular compound, and the number of alkyl groups having 10 or more carbon atoms as a suppression site in one molecule is 1 to 3. It is preferable that there is one, and more preferably one from the viewpoint of the ease of self-alignment of the organic compound having a suppression site.

  According to one aspect of the present invention, when the organic compound of the present invention is a polymer, the suppression site in one polymer molecule is a site containing an alkylene chain that does not contain an unsaturated bond having 2 to 60,000 carbon atoms. It is preferable that When the organic compound of the present invention is a polymer, when its action site interacts with a polishing object having a silicon-nitrogen bond, the molecular size of the polymer is bulkier than that of a low molecular compound, and therefore, due to steric hindrance, The approach of the polishing component can be suppressed. It is considered that the approach of the polishing component to the object to be polished can be more strongly suppressed when the suppression site in the polymer molecule is an alkylene chain that does not contain an unsaturated bond.

  Examples of the polymer include sodium polystyrene sulfonate. The weight average molecular weight of the polymer is preferably 300 or more, more preferably 500 or more, still more preferably 1000 or more, still more preferably 2,000 or more, still more preferably 5,000 or more, and particularly preferably 10,000 or more. . Further, the upper limit of the weight average molecular weight of the polymer is preferably 5,000,000 or less, more preferably 2,000,000 or less, and further preferably 1,200,000 or less. Within such a range, the approach of the polishing component can be suppressed, and a minute region existing in a polishing object having a silicon-nitrogen bond (for example, in a device pattern) can be protected. In addition, the weight average molecular weight of a polymer can be measured by the method as described in an Example.

  The number of suppression sites contained in the polymer molecule is calculated by dividing the weight average molecular weight of the polymer by the molecular weight of the structural unit constituting the polymer when the polymer is composed only of structural units having both an action site and a suppression site. Thus, the calculated value can be used.

  From the above, the organic compound according to the present invention includes n-octylamine, N, N-dimethyl-n-octylamine, octanenitrile, 4-octylpyridine, 4-heptylphenol, 4-n-octylbenzenecarboxylic acid. , Sodium 4-n-octylbenzenesulfonate, n-octyltrimethylammonium bromide, laurylphosphonic acid, n-octyldifluoroacetic acid, 4-n-octylphenylphosphonic acid, n-dodecyldichloroacetic acid, n-dodecylchloroacetic acid, lauryl Betaine, n-dodecylbromoacetic acid, 2- [sodiooxy (sulfonyl)] butanedioic acid 1-sodium 4-dodecyl, ammonium lauryl sulfate, p-dodecylbenzenesulfonic acid, disodium dodecyldiphenyl ether disulfonate, lauric sulfosuccinate Disodium, sodium polystyrene sulfonate are preferred. These may be used alone or in combination of two or more.

  Moreover, according to the preferable form of this invention, it is preferable that interaction is based on at least one selected from the group which consists of a hydrogen bond, an ionic bond, and a covalent bond. When the interaction is due to, for example, a hydrophobic interaction or an intermolecular force (van der Waals force), the interaction is not reliably adsorbed to the polishing object having a silicon-nitrogen bond, and the effect of the present invention can be obtained. There are times when it does not play. In particular, from the viewpoint of making it difficult for the organic compound (polishing rate inhibitor) of the present invention adsorbed on the surface of the polishing object (substrate) to be removed from the surface of the polishing object (substrate) by abrasive grains or a polishing pad. And at least one of strong bonds such as covalent bonds.

  In the present invention, it is sufficient that the polishing rate of the polishing object having a silicon-nitrogen bond can be suppressed in any one of acidic, neutral, and basic regions. In addition, when the pH is changed when it is desired to increase the polishing efficiency of other polishing objects, the polishing speed of the polishing object having the silicon-nitrogen bond in all acidic, neutral or basic regions. Is preferably suppressed.

  The content of the organic compound in the polishing composition of the present invention is not particularly limited, but is preferably 0.01 mM or more, more preferably 0.1 mM or more, and even more preferably 0.5 mM or more from the viewpoint of controlling polishing efficiency. Preferably, it is 1.0 mM or more, more preferably 1.5 mM or more, still more preferably 2.0 mM or more, and particularly preferably 2.5 mM or more. On the other hand, from the viewpoint of solubility and cost, 100 mM or less is preferable, 50 mM or less is more preferable, 30 mM or less is further preferable, 20 mM or less is further more preferable, 15 mM or less is further more preferable, 10 mM or less is more preferable, 5 mM or less is particularly preferable.

  As described above, the working site of the present invention can be chemically bonded to the surface of the polishing object having a silicon-nitrogen bond, and on the other hand, the polishing object is polished so that the suppression part of the organic compound faces the surface. Adsorb polishing components. Since the suppression part of this organic compound has high hydrophobicity, the organic compound having the same action part and the suppression part is assembled by the hydrophobic interaction, so that the surface of the polishing object having a silicon-nitrogen bond is collected. A suppression film is formed. Therefore, according to the present invention, polishing of an object to be polished having a silicon-nitrogen bond such as a silicon nitride film in at least one region (preferably in two or more regions) of acidic, neutral or basic. A polishing composition capable of sufficiently suppressing the speed can be provided.

  Further, according to the present invention, a polishing composition capable of sufficiently controlling the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be provided. In designing the structure, it is possible to prevent unintended layers from being polished. Therefore, it is possible to suppress the change in the height of the device and improve the electrical characteristics and the reliability of the device.

[Abrasive grain]
The polishing composition of the present invention contains abrasive grains.

  The abrasive used may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include particles made of metal oxides such as silica, alumina, ceria, titania, silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include latex particles, polystyrene particles, and polymethyl methacrylate (PMMA) particles. These abrasive grains may be used singly or as a composite thereof or as a mixture of two or more thereof. The abrasive grains may be commercially available products or synthetic products.

  In particular, when the zeta potential of the abrasive grains has the same sign as that of silicon nitride or the zeta potential difference increases, the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be suppressed. Among these abrasive grains, silica is preferable, and colloidal silica is particularly preferable from the viewpoint of suppressing generation of polishing flaws.

  Although the kind of colloidal silica which can be used is not specifically limited, For example, use of the surface-modified colloidal silica is possible. The surface modification of colloidal silica can be performed, for example, by mixing a metal such as aluminum, titanium or zirconium, or an oxide thereof with colloidal silica and doping the surface of the silica particles.

  Alternatively, the functional group of the organic acid can be chemically bonded to the surface of the silica particles, that is, the organic acid can be immobilized.

  Note that the organic acid is not fixed to the colloidal silica simply by allowing the colloidal silica and the organic acid to coexist. For example, if sulfonic acid, which is a kind of organic acid, is immobilized on colloidal silica, for example, “Sulphonic acid-functionalized silica through of thiol groups”, Chem. Commun. 246-247 (2003). Specifically, a silane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxysilane is coupled to colloidal silica and then oxidized with hydrogen peroxide to fix the sulfonic acid on the surface. The colloidal silica thus obtained can be obtained. The colloidal silica used in the examples is also modified with sulfonic acid groups in this way.

  Alternatively, if a carboxylic acid, which is a kind of organic acid, is immobilized on colloidal silica, for example, “Novel Silene Coupling Agents Containing a Photoboltable 2-Nitrobenzoyl Ether for the Introducing Carbon Carbohydrate”. Letters, 3, 228-229 (2000). Specifically, colloidal silica having a carboxylic acid immobilized on the surface can be obtained by irradiating light after coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to colloidal silica. .

  Of these, colloidal silica to which sulfonic acid is fixed is particularly preferable from the viewpoint of easy production.

  In colloidal silica that is not generally surface-modified, the isoelectric point of the zeta potential is in the vicinity of pH 3 to 4, and the agglomeration of abrasive grains may occur in the acidic region, which may impair dispersion stability. As a method for improving the dispersion stability of abrasive grains, it is generally considered effective to modify the functional group having a charge such as an acid group. Since this acid group can have a charge in a lower pH region as pKa is lower, a sulfonic acid group having a pKa value near 1 is useful. In such colloidal silica modified with a sulfonic acid group, a negative charge can be maintained in a wide pH range, so that the dispersion stability of the abrasive grains is improved.

  In the above description, the method for producing an anion sol has been described as a preferred form, but abrasive grains produced by a method for producing a cationic sol may be used. In addition, composite abrasive grains and abrasive grains having a core-shell structure can also be used.

  The lower limit of the average primary particle diameter of the abrasive grains in the polishing composition is preferably 5 nm or more, more preferably 7 nm or more, further preferably 10 nm or more, and more preferably 15 nm or more. More preferably, it is particularly preferably 25 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, further preferably 100 nm or less, still more preferably 70 nm or less, and 60 nm. More preferably, it is more preferably 50 nm or less.

  If it is such a range, defects, such as a scratch, can be suppressed on the surface of the object to be polished after polishing with the polishing composition. In addition, the average primary particle diameter of an abrasive grain is calculated based on the specific surface area of the abrasive grain measured by BET method, for example. This is also calculated in the embodiment of the present invention.

  The lower limit of the average secondary particle diameter of the abrasive grains in the polishing composition is preferably 5 nm or more, more preferably 7 nm or more, further preferably 10 nm or more, and preferably 25 nm or more. More preferably, it is more preferably 35 nm or more, still more preferably 45 nm or more, and particularly preferably 55 nm or more. Further, the upper limit of the average secondary particle diameter of the abrasive grains is preferably 300 nm or less, more preferably 260 nm or less, further preferably 220 nm or less, still more preferably 150 nm or less, It is more preferably 120 nm or less, still more preferably 100 nm or less, and particularly preferably 80 nm or less. If it is such a range, it can suppress more that a surface defect arises on the surface of the grinding | polishing target object after grind | polishing using polishing composition. In particular, when the average secondary particle diameter of the abrasive grains is reduced, it is considered that the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be suppressed.

  The secondary particles referred to here are particles formed by association of abrasive grains in the polishing composition, and the average secondary particle diameter of the secondary particles is measured by, for example, a dynamic light scattering method. be able to. This is also calculated in the embodiment of the present invention.

  The particle diameter D90 when the accumulated particle mass reaches 90% of the total particle mass from the fine particle side in the particle size distribution obtained by the laser diffraction scattering method in the abrasive grains in the polishing composition, and the total particle mass of all the particles The lower limit of the ratio of the diameter D10 of the particles when reaching 10% (also simply referred to as “D90 / D10” in the present specification) is preferably 1.1 or more, more preferably 1.2 or more. Preferably, it is 1.3 or more, more preferably 1.4 or more. The upper limit of D90 / D10 is not particularly limited, but is preferably 5.0 or less, more preferably 3.0 or less, further preferably 2.5 or less, and 2.0 or less. More preferably, it is more preferably 1.8 or less. If it is such a range, it can suppress more that a surface defect arises on the surface of the grinding | polishing target object after grind | polishing using polishing composition. This is also calculated in the embodiment of the present invention.

  The lower limit of the content of the abrasive grains in the polishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and more preferably 0.1% by mass or more. More preferably, it is more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more. When the lower limit is such, it is preferable in obtaining sufficient polishing efficiency for a polishing object other than a polishing object having a silicon-nitrogen bond such as a silicon nitride film.

  Further, the upper limit of the content of the abrasive grains in the polishing composition is preferably 50% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, and 8 More preferably, it is more preferably 6% by mass or less, and particularly preferably 4% by mass or less. When the upper limit is such, the cost of the polishing composition can be suppressed, and the occurrence of surface defects on the surface of the object to be polished after polishing using the polishing composition can be further suppressed. In particular, it is considered that when the content of abrasive grains in the polishing composition is decreased, the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be suppressed.

[Dispersion medium]
The polishing composition of the present invention preferably uses a dispersion medium for dispersing each component. As the dispersion medium, an organic solvent and water are conceivable, but it is more preferable to include water among them.

  From the viewpoint of inhibiting contamination of the object to be polished and the action of other components, water containing as little impurities as possible is preferable. Specifically, pure water, ultrapure water, or distilled water from which foreign ions are removed through a filter after removing impurity ions with an ion exchange resin is preferable.

[Polishing object]
As described above, the present invention provides a polishing composition capable of sufficiently controlling an object to be polished having a silicon-nitrogen bond in at least one of acidic, neutral and basic regions.

  As a polishing object having a silicon-nitrogen bond, a silicon nitride film (SiN), a silicon oxynitride film (SiON film), a silicon carbonitride (SiCN) film, a silicon oxycarbonitride film (SiOCN film), a nitrogen-added hafnium silicate film (HfSiON film), sialon film (SiAlON film), and the like.

[Other ingredients]
The polishing composition of the present invention may further contain other components such as a pH adjuster, an oxidizing agent, a reducing agent, a surfactant, a water-soluble polymer, and an antifungal agent, if necessary.

  Hereinafter, the pH adjuster, the oxidizing agent, the surfactant, the water-soluble polymer, and the fungicide will be described.

  In addition, tentatively, a compound having an action site that interacts with a polishing object having a silicon-nitrogen bond and a suppression part that suppresses a polishing component that polishes the polishing object from approaching the polishing object. However, when it can also act as “another component”, the present invention classifies it as an organic compound of the present invention.

(PH adjuster)
The polishing composition of the present invention suppresses the polishing rate of the polishing object having the silicon-nitrogen bond in at least one of acidic, neutral and basic regions. Therefore, the pH adjuster is preferably used for adjusting to an acidic or basic region.

  In the present invention, the acidic region means a pH of 0 or more and less than 7, preferably pH 1 to 4. In the present invention, the neutral region means pH 7. In the present invention, the basic region means a pH of more than 7 and 14 or less, preferably pH 8-13. In addition, the value of pH in this invention shall say the value measured on the conditions as described in an Example.

Specific examples of the pH adjusting agent for adjusting to the acidic region may be any of an inorganic compound and an organic compound. For example, sulfuric acid (H ₂ SO ₄ ), nitric acid, boric acid, carbonic acid, hypoxia Inorganic acids such as phosphoric acid, phosphorous acid and phosphoric acid; formic acid, acetic acid, propionic acid, benzoic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid Examples thereof include carboxylic acids such as acid and lactic acid, and organic acids such as organic sulfuric acid such as methanesulfonic acid, ethanesulfonic acid, and isethionic acid. In addition, in the case where the above acid is a divalent or higher acid (for example, sulfuric acid, carbonic acid, phosphoric acid, oxalic acid, etc.), it may be in a salt state as long as at least one proton (H ⁺ ) can be released. Specifically, for example, ammonium hydrogen carbonate, ammonium hydrogen phosphate (the type of the cation species of the counter is basically arbitrary, but a weak base cation (ammonium, triethanolamine, etc.) is preferred).

  In particular, when the salt form is used, it is considered that the lower the salt concentration (slurry conductivity), the more the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be suppressed. In particular, when a salt form is used, the salt concentration (the conductivity of the slurry) increases, and the thickness of the electric double layer on the abrasive grain surface decreases. Therefore, since the electrostatic repulsive force of the abrasive grains is weakened, there is a concern that the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film may be improved. For this reason, in the polishing composition of the present invention, it is more preferable that the pH adjuster for adjusting to the acidic region does not contain a salt. Examples of such salts include halogen acids such as hydrochloric acid, ammonium salts of inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, and carbonic acid, potassium salts, amine salts, acetic acid, citric acid, oxalic acid, maleic acid, and other organic acids. Ammonium salt, potassium salt, amine salt.

  Specific examples of the pH adjusting agent for adjusting to the basic region may be any of an inorganic compound and an organic compound, but alkali metal hydroxides or salts thereof, quaternary ammonium, hydroxide hydroxide Quaternary ammonium or a salt thereof, ammonia, amine and the like can be mentioned.

  Specific examples of the alkali metal include potassium and sodium. Specific examples of the salt include carbonate, hydrogen carbonate, sulfate, acetate, and the like.

  Specific examples of the quaternary ammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium and the like.

  Specific examples of the quaternary ammonium hydroxide or a salt thereof include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide.

  Especially, it is more preferable that polishing composition contains ammonia, an amine, and potassium as a base from a viewpoint of metal contamination prevention and the ease of the spreading | diffusion of the metal ion in a semiconductor device structure. Specific examples include potassium hydroxide (KOH), potassium carbonate, potassium hydrogen carbonate, potassium sulfate, potassium acetate, and potassium chloride.

(Oxidant)
Specific examples of the oxidizing agent include hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, perchloric acid; persulfates such as sodium persulfate, potassium persulfate, ammonium persulfate, perchlorate and periodate. Examples thereof include halogen-based oxidizing agents such as acids. These oxidizing agents may be used alone or in combination of two or more.

  The lower limit of the content (concentration) of the oxidizing agent in the polishing composition is preferably 0.001% by mass or more, and more preferably 0.01% by mass or more. By setting the lower limit in this way, there is an advantage that the polishing efficiency can be increased without increasing the abrasive concentration when polishing an object whose polishing efficiency is improved when an oxidizing agent is added. Moreover, it is preferable that the upper limit of content (concentration) of the oxidizing agent in polishing composition is 30 mass% or less, More preferably, it is 10 mass% or less. By setting the upper limit in this way, the material cost of the polishing composition can be suppressed, and in addition, there is an advantage that the load of the treatment of the polishing composition after polishing use, that is, the waste liquid treatment can be reduced. . In addition, there is an advantage that excessive oxidation of the surface of the object to be polished by the oxidizing agent hardly occurs.

(Reducing agent)
Moreover, the polishing composition of the present invention may contain a reducing agent. As the reducing agent, conventionally known ones used in polishing compositions can be included. For example, in the case of organic substances, hydrazine, formic acid, oxalic acid, formaldehyde aqueous solution, ascorbic acid, glucose and other reducing sugars, inorganic substances In, nitrous acid or its salt, phosphorous acid or its salt, hypophosphorous acid or its salt, sulfurous acid or its salt, thiosulfuric acid or its salt, lithium aluminum hydride, sodium borohydride, multiple stable valences Metal and its compounds. By suppressing oxidation of any metal with a reducing agent, corrosion of the metal can be suppressed and polishing efficiency can be controlled.

  The lower limit of the content (concentration) of the reducing agent in the polishing composition is preferably 0.001% by mass or more, and more preferably 0.01% by mass or more. By setting the lower limit in this way, there is an advantage that the polishing efficiency can be increased without increasing the abrasive concentration when polishing a polishing object whose polishing efficiency is improved by adding a reducing agent. In addition to this, by adding a reducing agent, it is possible to suppress corrosion when an arbitrary metal is contained in the object to be polished. Moreover, it is preferable that the upper limit of content (concentration) of the reducing agent in polishing composition is 30 mass% or less, More preferably, it is 10 mass% or less. By setting the upper limit in this way, the material cost of the polishing composition can be suppressed, and in addition, there is an advantage that the load of the treatment of the polishing composition after polishing use, that is, the waste liquid treatment can be reduced. .

(Surfactant)
A surfactant may be contained in the polishing composition. The surfactant improves the cleaning efficiency after polishing by imparting hydrophilicity to the polished surface after polishing, and can prevent the adhesion of dirt. In addition to improving the cleanability, step performance such as dishing can be improved by selecting an appropriate surfactant.

  The surfactant may be any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant. One of these surfactants may be used alone, or two or more thereof may be used in combination.

  The content of the surfactant in the polishing composition is preferably 0.001 g / L or more, more preferably 0.005 g / L or more. By setting it as such a lower limit, the cleaning efficiency after polishing is further improved. Further, by selecting an appropriate surfactant, step performance such as dishing can be improved.

(Water-soluble polymer)
The water-soluble polymer is a temperature at which the water-soluble polymer is most dissolved, and when it is dissolved in water at a concentration of 0.5% by mass and filtered through a G2 glass filter (maximum pores 40 to 50 μm). The mass of the insoluble matter to be filtered out is within 50 mass% of the added water-soluble polymer.

  When a water-soluble polymer is added to the polishing composition, the surface roughness of the polishing object after polishing using the polishing composition is further reduced. One of these water-soluble polymers may be used alone, or two or more thereof may be used in combination.

  The content of the water-soluble polymer in the polishing composition is preferably 0.01 g / L or more, more preferably 0.05 g / L or more. By setting it as such a lower limit, the surface roughness of the polishing surface by the polishing composition is further reduced.

  The content of the water-soluble polymer in the polishing composition is preferably 100 g / L or less, more preferably 50 g / L or less. By setting such an upper limit, the remaining amount of the water-soluble polymer on the polishing surface is reduced, and the cleaning efficiency is further improved.

(Anti-mold agent)
Examples of the antiseptic and fungicide that can be added to the polishing composition according to the present invention include 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one. And the like, isothiazoline-based preservatives such as paraoxybenzoates, and phenoxyethanol. These antiseptics and fungicides may be used alone or in combination of two or more.

  As described above, in particular, an action site that interacts with a polishing object having a silicon-nitrogen bond, and a suppression part that suppresses a polishing component that polishes the polishing object from approaching the polishing object; By having the constitution that the polishing composition contains an organic compound having the above, the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film can be sufficiently controlled. Here, the polishing environment is appropriately adjusted depending on the polishing application or the like. That is, polishing may be performed in an acidic environment, polishing may be performed in a neutral environment, and polishing may be performed in a basic environment. In other words, since the polishing rate of the polishing object having the silicon-nitrogen bond is suppressed in at least one of the acidic, neutral or basic regions of the present invention, the specific pH region depends on the polishing application and the like. A polishing composition capable of sufficiently controlling the polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film may be appropriately selected and used. Therefore, from another point of view, it is added that it is not meaningful to compare the polishing rate between different pH ranges.

  Here, the polishing rate of an object to be polished having a silicon-nitrogen bond such as a silicon nitride film in an acidic environment is preferably less than 330 [Å / min], and more preferably 300 [Å / min] or less. More preferably 290 [Å / min] or less, still more preferably 200 [Å / min] or less, still more preferably 80 [Å / min] or less, and still more preferably 70 [［/ min] or less. Å / min] or less, more preferably 50 [Å / min] or less, and particularly preferably 30 [Å / min] or less. The lower limit of the polishing rate is not particularly limited, and is 0 [Å / min] or more.

  Note that colloidal silica has a negative charge on the acidic side of the zeta potential. Here, when colloidal silica is used as the abrasive grains, it is difficult to suppress the polishing rate in an acidic environment, but the point to which the present invention should be focused is that it is suppressed even in acidic conditions.

  The polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film in a neutral environment is preferably less than 13 [Å / min], more preferably 12 [１２ / min] or less. More preferably, it is 11 [Å / min] or less. The lower limit of the polishing rate is not particularly limited, and is 0 [Å / min] or more.

  The polishing rate of a polishing object having a silicon-nitrogen bond such as a silicon nitride film in a basic environment is preferably less than 9 [Å / min], more preferably 8 [８ / min] or less. More preferably, it is 7 [Å / min] or less. The lower limit of the polishing rate is not particularly limited, and is 0 [Å / min] or more.

  In addition, a polishing rate shall mean the value measured by the method as described in an Example.

  In addition to the technical effects of the present invention, not only can the polishing target having a silicon-nitrogen bond, such as a silicon nitride film, be sufficiently controlled, but the polishing target can be polysilicon, Even when an oxide film is included, the polishing rate of a polishing object having a silicon-nitrogen bond, such as a silicon nitride film, can be suppressed while maintaining the same polishing rate.

<Method for producing polishing composition>
In this invention, it is a manufacturing method of the polishing composition which suppresses the polishing rate of the said grinding | polishing target object which has the said silicon- nitrogen bond in at least 1 area | region of acidic, neutral, or basic, Comprising: (1) An organic compound; and (2) abrasive grains; a working site where the organic compound interacts with a polishing object having a silicon-nitrogen bond; and a polishing component for polishing the polishing object There is also provided a method for producing a polishing composition having a suppression site that suppresses the approach of the polishing object.

  Although the manufacturing method of said polishing composition is not restrict | limited in particular, It can obtain by stirring and mixing each component which comprises the polishing composition of this invention, and another component as needed. it can.

  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. Further, the mixing time is not particularly limited.

<Polishing method>
In this invention, the grinding | polishing method which grind | polishes the grinding | polishing target object which has a silicon- nitrogen bond with said polishing composition or the polishing composition obtained by said manufacturing method is provided.

  As a polishing apparatus, a general holder having a polishing surface plate on which a holder for holding a substrate having a polishing object and a motor capable of changing the number of rotations are attached and a polishing pad (polishing cloth) can be attached. A polishing apparatus 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 grooved so that the polishing composition accumulates.

  The polishing conditions are not particularly limited. For example, the rotation speed of the polishing platen is preferably 10 to 500 rpm, the rotation speed of the head (carrier) is preferably 10 to 50 rpm, and the pressure applied to the substrate having the object to be polished ( The polishing pressure is preferably from 0.1 to 10 psi. The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying with a pump or the like is employed. Although the 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. Further, the polishing time is not particularly limited.

<Method for suppressing polishing rate of polishing object having silicon-nitrogen bond>
In the present invention, (1) an action site that interacts with a polishing object having a silicon-nitrogen bond, and a suppression part that suppresses a polishing component that polishes the polishing object from approaching the polishing object; (2) Abrasive grains are used to polish the object to be polished by polishing the object to be polished in at least one of acidic, neutral, and basic regions. A method for suppressing the polishing rate of a polishing object having a nitrogen bond is provided.

  As for the specific description of the constituent features of the invention, the above description is equally valid, and the description thereof is omitted here.

  The present invention will be described in further detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

(Preparation of polishing composition)
Polishing compositions of Examples and Comparative Examples were prepared by using 2% by mass of abrasive grains (sulfonic acid group-modified colloidal silica, average primary particle size: 35 nm, average secondary particle size: 65 nm, D90 / D10: 1.6), pH Prepared by mixing 3 mM organic compounds shown in Table 1 and Table 2 in pure water (mixing temperature: about 25 ° C., mixing time: about 10 minutes).

The pH of the polishing composition was adjusted to 2, 7, and 10 by adding appropriate amounts of H ₂ SO ₄ and KOH.

  The pH of the polishing composition (liquid temperature: 25 ° C.) was confirmed by a pH meter (manufactured by Horiba, Ltd., model number: LAQUA).

(Polishing performance evaluation)
Using the obtained polishing composition, the polishing rate when the polishing object (SiN) was polished under the following polishing conditions was measured.

<Polishing conditions>
Polishing machine: Single-side CMP polishing machine (ENGIS)
Polishing pad: Polyurethane pad (IC1010: manufactured by Rohm and Haas)
Pressure: 3.04 psi
Platen (surface plate) rotation speed: 90rpm
Head (carrier) rotation speed: 40 rpm
Flow rate of polishing composition: 100 ml / min
Polishing time: 60 sec
<Polishing speed>
The polishing rate (polishing rate) was calculated by the following formula.

  The film thickness was evaluated by determining with a light interference type film thickness measuring device (model number: Lambda Ace manufactured by Dainippon Screen Mfg. Co., Ltd.) and dividing the difference by the polishing time.

  Tables 1 and 2 below show the measurement results of the polishing rate.

<Weight average molecular weight>
The measurement conditions of the weight average molecular weight of sodium polystyrene sulfonate which is a polymer are as follows.

GPC device: manufactured by Shimadzu Corporation Model: Prominence + ELSD detector (ELSD-LTII)
Column: VP-ODS (manufactured by Shimadzu Corporation)
Mobile phase A: MeOH
B: Acetic acid 1% aqueous solution Flow rate: 1 mL / min
Detector: ELSD temp. 40 ° C., Gain 8, N ₂ GAS 350 kPa
Oven temperature: 40 ° C
Injection volume: 40 μl.

<Number of working sites>
The number of action sites of sodium polystyrene sulfonate, which is a polymer, was calculated by the following calculation formula.

<Number of suppression sites>
The number of sites of inhibition of sodium polystyrene sulfonate, which is a polymer, was calculated by dividing the weight average molecular weight of the polymer by the molecular weight of the structural unit constituting the polymer.

Claims (7)

(1) an action site that interacts with a polishing object having a silicon-nitrogen bond;
Suppressing the polishing component for polishing the polishing object from being approached to the polishing object;
An organic compound having:
(2) abrasive grains;
Polishing composition which suppresses the grinding | polishing speed | rate of the said grinding | polishing target object which has the said silicon- nitrogen bond in at least 1 area | region of acidic, neutral, or basic which has.   The polishing composition according to claim 1, wherein the suppression site is a site having 3 or more carbon atoms.   The polishing composition according to claim 1, wherein the active site has a pKa of 5 or less.   The polishing composition according to claim 1, wherein the interaction is at least one selected from a hydrogen bond, an ionic bond, and a covalent bond.   The polishing composition according to claim 1, wherein the polishing object having a silicon-nitrogen bond is a silicon nitride film.   The polishing composition according to any one of claims 1 to 5, wherein the organic compound has two or more active sites in one molecule. (1) an action site that interacts with a polishing object having a silicon-nitrogen bond;
An organic compound having a suppression site that inhibits a polishing component that polishes the polishing object from approaching the polishing object;
(2) abrasive grains;
By polishing the polishing object using a polishing composition having the above, the polishing rate of the polishing object having a silicon-nitrogen bond is suppressed in at least one of acidic, neutral and basic regions. Method.