TW201518488A - Polishing composition and method for producing same - Google Patents

Abstract

Provided is a polishing composition which enables the improvement in a polishing rate while rarely affecting the quality of a surface. Provided is a polishing composition comprising abrasive grains, water and a quaternary ammonium cation represented by general formula (A). [In the formula, R1, R2, R3 and R4 may be the same as or different from one another and independently represent an organic group, wherein at least one of R1, R2, R3 and R4 represents an organic group having 3 or more carbon atoms.]

Description

Grinding composition and method of producing the same

The present invention relates to a composition for polishing and a method for producing the same. The present application claims priority based on Japanese Patent Application No. 2013-145771, filed on Jan.

The surface of the wafer used as a constituent element of the semiconductor device or the like is generally modified into a high-quality mirror surface by a polishing step (rough polishing step) and a polishing step (precision polishing step). The above polishing step typically includes a pre-polishing step (pre-grinding step) and a final polishing step (final grinding step). As the polishing method in the above polishing step, a chemical mechanical polishing (CMP) method using a polishing composition containing water, abrasive grains, and a polishing accelerator is known. A representative example of the polishing accelerator is ammonia. Patent Documents 1 and 2 are listed in the technical literature on the polishing composition.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2001-3036

[Patent Document 2] Japanese Patent Application Publication No. 2005-518668

A polishing composition for polishing a semiconductor substrate such as a germanium wafer or another substrate is required to have a high-quality surface performance after polishing. On the other hand, from the viewpoint of productivity and the like, it is also desired to increase the polishing rate. However, generally, the surface quality after polishing is inversely related to the polishing rate, and the surface quality is degraded when the polishing rate is increased.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polishing composition which can increase the polishing rate while suppressing the influence on surface quality. Another object of the present invention is to provide a method for producing the polishing composition.

The inventors of the present invention have investigated the components contained in the polishing composition which can increase the polishing rate while suppressing the influence on the surface quality. As a result, it has been found that the polishing composition can contain a quaternary ammonium cation having a specific structure, and the polishing rate can be greatly improved while suppressing the influence on the surface quality, and thus the present invention has been completed.

According to the present specification, a polishing composition containing abrasive grains, water, and a 4-stage ammonium cation represented by the following general formula (A) is provided.

(wherein R ¹ , R ² , R ³ and R ⁴ are the same or different and are each an organic group, at least one of which is an organic group having 3 or more carbon atoms).

The polishing composition containing the quaternary ammonium cation having an organic group having 3 or more carbon atoms on the nitrogen atom can greatly increase the polishing rate while suppressing the influence on the surface quality. According to the present specification, as a further aspect of the polishing composition, there is provided a method for producing a polishing composition characterized by comprising an abrasive grain, water, and a fourth-order ammonium cation represented by the above formula (A). A composition for polishing.

A preferred example of one of the above-described ammonium cations (hereinafter sometimes referred to as "ammonium cation (A)") represented by the above formula (A) is that R ¹ , R ² , R ³ and R ⁴ are the same or different. All are hydrocarbon based. According to the ammonium (A) of this structure, it is easy to exhibit the effect of suppressing the influence on the surface quality and increasing the polishing rate. Further, when R ¹ , R ² , R ³ and R ⁴ are each a hydrocarbon group, it is preferred from the viewpoint of dispersion stability of the polishing composition and the like. For example, ammonium (A) in which R ¹ , R ² , R ³ and R ⁴ are all alkyl groups can be preferably used. The above effect can be further exhibited by the ammonium (A) in which two or more of R ¹ , R ² , R ³ and R ⁴ are a hydrocarbon group having 3 or more carbon atoms.

Another preferred example of the ammonium (A) is exemplified by the fact that R ¹ , R ² , R ³ and R ⁴ are the same or different and are each an alkyl group having 3 or more carbon atoms. By using the polishing composition containing the ammonium (A), the polishing rate can be effectively increased while suppressing the influence on the surface quality.

Preferably, the abrasive composition disclosed herein is such that the abrasive particles are cerium oxide particles. In the polishing using the cerium oxide particles as the abrasive grains, the polishing rate improving effect can be preferably exhibited by the ammonium (A).

Preferably, the polishing composition disclosed herein is such that the polishing composition further contains a water-soluble polymer. In the polishing using the polishing composition containing a water-soluble polymer, the polishing rate improving effect can be preferably exhibited by ammonium (A).

The polishing compositions disclosed herein are suitable for use in the polishing of tantalum wafers, for example, preferably for polishing of polished tantalum wafers. Ideal for final polishing of tantalum wafers. Moreover, the resistivity in the germanium wafer is 0.1Ω. In the low-resistance wafer of cm or less, the polishing rate improvement effect can be effectively exhibited by ammonium (A).

Hereinafter, preferred embodiments of the present invention will be described. Further, the necessity of the present invention other than the matters specifically mentioned in the present specification is familiar to those skilled in the art who can grasp the design matter based on the prior art in the technical field. The present invention can be implemented based on the contents disclosed in the specification and the technical knowledge in the field. <abrasive grain>

The material or properties of the abrasive grains disclosed herein are not particularly limited, and may be appropriately selected depending on the purpose of use of the polishing composition or the form of use. Make Examples of the abrasive grains are inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles are cerium oxide particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium oxide particles, zirconia particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and iron oxide (Bengala) particles. Oxide particles such as nitride particles; nitride particles such as tantalum nitride particles and boron nitride particles; carbide particles such as tantalum carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate or barium carbonate. Specific examples of the organic particles are polymethyl methacrylate (PMMA) particles or poly(meth)acrylic particles (herein, (meth)acrylic acid means acrylic acid and methacrylic acid), polyacrylonitrile particles, and the like. . These abrasive grains may be used alone or in combination of two or more.

The abrasive grains are preferably inorganic particles, and those formed of a metal or a semimetal oxide are preferred. Preferred examples of abrasive particles that can be used in the techniques disclosed herein are cerium oxide particles. For example, when the technique disclosed herein is used for the polishing composition usable in the polishing of the wafer, it is preferred to use the cerium oxide particles as the abrasive particles. The reason is that when the object to be polished is a germanium wafer, if the cerium oxide particles formed of the same element and oxygen atom as the object to be polished are used as the abrasive grains, metal or semimetal which is different from bismuth does not occur after polishing. The residue does not cause any contamination of the surface of the wafer or the deterioration of electrical characteristics of the wafer due to diffusion of a metal or a semimetal different from germanium into the object to be polished. In addition, since the hardness of tantalum and cerium oxide is close to that, it can be ground without causing excessive damage to the surface of the wafer. Based on this point of view, as one of the preferred polishing compositions, it is exemplified that only cerium oxide particles are contained as abrasive grains. The composition for polishing. Further, cerium oxide has a property of being easily obtained in a high purity. This is also a reason why the cerium oxide particles are preferably used as the abrasive grains. Specific examples of the cerium oxide particles are colloidal cerium oxide, fumed cerium oxide, precipitated cerium oxide, and the like. From the viewpoint that scratches are less likely to occur on the surface of the object to be polished, a surface having a low haze can be further realized. Preferred examples of the ceria particles include colloidal ceria and fumed ceria. Among them, colloidal cerium oxide is preferred. For example, colloidal cerium oxide can be preferably used as the abrasive particles of the polishing composition used for the polishing (especially final polishing) of the ruthenium wafer.

The true specific gravity of the cerium oxide constituting the cerium oxide particles is preferably 1.5 or more, more preferably 1.6 or more, still more preferably 1.7 or more. As the true specific gravity of the cerium oxide increases, the polishing rate (the amount of the surface of the object to be polished is removed per unit time) can be increased when the ruthenium wafer is polished. From the viewpoint of reducing the scratches generated on the surface (polishing surface) of the object to be polished, it is preferably a cerium oxide particle having a true specific gravity of 2.2 or less. The true specific gravity of cerium oxide can be measured by a liquid displacement method using ethanol as a replacement liquid.

In the technique disclosed herein, the abrasive particles contained in the polishing composition may be in the form of primary particles or in the form of secondary particles in which a plurality of primary particles are agglomerated. Further, abrasive grains in the form of primary particles and secondary particles may be mixed. Preferably, at least a part of the abrasive grains are contained in the polishing composition in the form of secondary particles.

The average primary particle diameter of the abrasive grains D _P1 is not particularly limited, but from the viewpoint of grinding efficiency and the like, preferably 5nm or more, and more preferably 10nm or more. The average primary particle diameter D _{P1 is} preferably 15 nm or more, more preferably 20 nm or more (for example, more than 20 nm) from the viewpoint of obtaining a higher polishing effect (for example, reduction in turbidity, effect of defect removal, etc.). Further, from the viewpoint of easily obtaining a surface having higher smoothness, the average primary particle diameter D _{P1 of the} abrasive grains is preferably 100 nm or less, more preferably 50 nm or less, still more preferably 40 nm or less. The techniques disclosed herein are based on the ease of obtaining higher quality surfaces (eg, LPD (Light Point Defect) or PID (Polishing Induced Defect) and other defects) It can be preferably carried out in the form of abrasive grains having an average primary particle diameter D _P1 of 35 nm or less.

Further, in the technique disclosed herein, the average primary particle diameter D _{P1 of the} abrasive grains can be, for example, a specific surface area S (m ² /g) measured by the BET method, and an average primary particle diameter D _P1 (nm) = 2727 / S. Calculated. The specific surface area of the abrasive grains can be measured by, for example, a surface area measuring device manufactured by Micromeritics Co., Ltd. under the trade name "Flow Sorb II 2300".

The average secondary particle diameter D _{P2 of the} abrasive grains is not particularly limited, but is preferably 10 nm or more, and more preferably 20 nm or more, from the viewpoint of polishing rate and the like. The average secondary particle diameter D _{P2 is} preferably 30 nm or more, more preferably 35 nm or more, and still more preferably 40 nm or more (for example, more than 40 nm) from the viewpoint of obtaining a higher polishing effect. Further, from the viewpoint of obtaining a surface having higher smoothness, the average secondary particle diameter D _P2 of the abrasive grains is preferably 200 nm or less, preferably 150 nm or less, more preferably 125 nm or less. The technique disclosed herein is also preferably based on the use of abrasive grains having an average secondary particle diameter D _{P2 of} less than 100 nm, based on the viewpoint of easily obtaining a higher quality surface (for example, a surface in which defects such as LPD or PID are reduced). Implementation of the situation.

Further, in the technique disclosed herein, the average secondary particle diameter D _{P2 of the} abrasive grains can be determined by using a dynamic light scattering method as a volume average particle diameter by using, for example, a model "UPA-UT151" manufactured by Nikkiso Co., Ltd. .

The average secondary particle diameter D _P2 of the abrasive particles is generally equal to the average primary particle diameter D _P1 or more of the abrasive grains (D _P2 /D _P1 ≧1), and is typically larger than D _P1 (D _P2 /D _P1 >1). Although not particularly limited, the D _P2 /D _{P1 of the} abrasive grains is preferably in the range of 1.2 to 4, preferably in the range of 1.5 to 3, more preferably 1.7, based on the polishing effect and the surface smoothness after polishing. ~2.8 range.

The shape (outer shape) of the abrasive grains may be spherical or non-spherical. Specific examples of the non-spherical abrasive grains are exemplified by a peanut shape (that is, a shape of a groundnut shell), a scorpion shape, a golden sugar shape, a football shape, and the like. For example, abrasive grains in which the abrasive grains are mostly peanut-shaped can be preferably used.

Although not particularly limited, the average value (average aspect ratio) of the major axis/short diameter ratio of the primary particles of the abrasive grains is preferably 1.05 or more, more preferably 1.1 or more. Higher grinding speeds can be achieved by increasing the average aspect ratio of the abrasive particles. Further, the average aspect ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, still more preferably 1.5 or less, from the viewpoint of reducing scratches.

The shape (outer shape) or the average aspect ratio of the above abrasive grains can be grasped by, for example, observation by an electron microscope. Master the average aspect ratio The sequence is, for example, using a scanning electron microscope (SEM), and for a predetermined number (for example, 200) of abrasive particles that can recognize the shape of the individual particles, a minimum rectangle that is circumscribed to each particle image is drawn. Next, for the rectangle drawn on each particle image, the length of the long side (the value of the long diameter) is divided by the length of the short side (the value of the short diameter) as the long diameter/short diameter ratio (aspect ratio) ) and calculate. The average aspect ratio can be obtained by arithmetically averaging the above-described predetermined number of particle aspect ratios.

<Ammonium (A)>

The polishing composition disclosed herein contains a 4- to 4-ammonium cation (typically a 4- to ammonium cation represented by the above formula (A)) having at least one organic group having 3 or more carbon atoms on a nitrogen atom. The polishing composition may contain one type of the above-mentioned four-stage ammonium cation, or may be contained in combination of two or more. By including the above-described fourth-order ammonium cation in the polishing composition, it is possible to effectively increase the polishing rate while suppressing the influence on the surface quality. The following discussion does not limit the scope of the present invention. However, as a reason for obtaining this effect, it is considered that the abrasive grains are easily retained on the surface of the object to be polished by the molecular structure of the above-described fourth-order ammonium cation. That is, when the surface of the abrasive grains in the polishing composition is negatively charged, the above-mentioned 4-stage ammonium cation is easily adsorbed on the surface of the abrasive particles. On the other hand, the organic group having 3 or more carbon atoms tends to exhibit affinity for the surface of the object to be polished. Since the abrasive grains are easily left on the surface of the object to be polished by the affinity, the abrasive grains can be used to provide a more effective mechanical polishing action, and it is considered that the fourth-order ammonium cation having the above organic group is adsorbed to the abrasive grains. Suppressing surface quality The decline.

In the ammonium (A), the substituents R ¹ , R ² , R ³ and R ⁴ on the nitrogen atom may be the same or different. From the viewpoint of the affinity for the surface of the object to be polished, it is preferred that the above substituents are all nonionic groups of ammonium (A). This is also advantageous from the viewpoint of the dispersion stability of the abrasive grains adsorbing the above ammonium (A). Moreover, it is also preferable from the viewpoint of preventing the occurrence of aggregates in the polishing composition or improving the filterability and the like.

At least one of the substituents on the nitrogen atom is an organic group having 3 or more carbon atoms, preferably an organic group having 4 or more carbon atoms. The number of carbon atoms of the remaining three substituents is not particularly limited as long as it is 1 or more. For example, the number of carbon atoms of one substituent may be 3 or more, and the number of carbon atoms of the remaining three substituents may be 1 or 2, respectively; the number of carbon atoms of 2 substituents is 3 or more, and the remaining 2 substituents The number of carbon atoms is 1 or 2, and the four substituents are each having a structure of 3 or more carbon atoms.

The upper limit of the number of carbon atoms of each substituent is not particularly limited, but is usually preferably 30 or less, more preferably 25 or less, and still more preferably 20, from the viewpoints of ease of preparation of the polishing composition or storage stability. the following. In a preferred embodiment, the number of carbon atoms of each of the substituents of the ammonium (A) may be 8 or less (more preferably 6 or less).

Of the ^{R 1, R 2, R 3} , R ⁴ typically total number of carbon atoms of 6 or more, based on the affinity of the other surface of the object to be polished is preferably 9 or more views, more preferably 12 or more, preferably e.g. 15 or more. The upper limit of the total number of carbon atoms is not particularly limited. However, the total number of carbon atoms is preferably 48 or less, and preferably 32 or less, from the viewpoint of preventing the occurrence of aggregates in the polishing composition or improving the filterability.

The substituent on the above nitrogen atom is preferably one having a high hydrophobicity. Examples of the substituent having a high hydrophobicity are exemplified by a hydrocarbon group; a group (halogenated hydrocarbon group) in which a part or all of a hydrogen atom of the hydrocarbon group is substituted with a halogen atom such as a fluorine atom or a chlorine atom. For example, ammonium (A) in which at least one of R ¹ , R ² , R ³ and R ⁴ is a hydrocarbon group having 3 or more carbon atoms is preferred. An example of such an ammonium (A) is exemplified by trimethylphenylammonium. More preferably ^{R 1, R 2, R 3} , R 4 in the two or more ammonium (A) of 3 or more carbon atoms of the hydrocarbon group, and more preferably ^{R 1, R 2, R 3} , R 4 are Ammonium (A) having a hydrocarbon group having 3 or more carbon atoms.

The hydrocarbon group may be a saturated or unsaturated aliphatic group such as an alkyl group, a cycloalkyl group or an alkenyl group; or a group having an aromatic structural moiety such as an aryl group or an arylalkyl group. Examples of the alkyl group are a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a lauryl group, a cetyl group, a stearyl group and the like. Examples of the cycloalkyl group are a cyclohexyl group, a methylcyclohexyl group, a cycloheptyl group and the like. Specific examples of the alkenyl group are hexenyl group, oleyl group and the like. Examples of the aryl group are a substituted phenyl group such as a phenyl group or a methylphenyl group. Examples of the arylalkyl group are a substituted benzyl group such as a benzyl group or a methylbenzyl group. Further, the butyl group exemplified herein is a concept including various structural isomers thereof (n-butyl group, isobutyl group, second butyl group, and tert-butyl group). The same is true for other hydrocarbon groups.

Preferable examples of the ammonium (A) include those in which R ¹ , R ² , R ³ and R ⁴ are each an alkyl group having 3 or more carbon atoms. For example, R ¹ , R ² , R ³ and R ⁴ are each preferably an alkyl group having 3 to 8 carbon atoms. Examples of the ammonium (A) are symmetrical four-stage ammonium cations such as tetrapropylammonium, tetrabutylammonium, tetraamylammonium, tetrahexylammonium, tetraheptylammonium, tetraoctylammonium or the like; a 4-stage ammonium cation having an asymmetric structure such as propyl ammonium, tributyl amyl ammonium, triamylpropyl ammonium, tripentylbutyl ammonium, trihexylpropyl ammonium or trihexyl butyl ammonium. Preferably, R ¹ , R ² , R ³ and R ⁴ are each a linear alkyl group (A), more preferably a symmetrical structure. Among them, tetrapropylammonium, tetrabutylammonium, tetraamylammonium, and tetrahexylammonium are preferred, and tetrapropylammonium and tetrabutylammonium are more preferred. The most preferred ammonium (A) is a tetrabutylammonium wherein R ¹ , R ² , R ³ and R ⁴ are both linear butyl groups.

In another preferred embodiment of the ammonium (A), one of R ¹ , R ² , R ³ and R ⁴ is an alkyl group having 3 or more carbon atoms (typically 6 or more, preferably 8 or more, for example, 12 or more). The remaining three are methyl. In this case, the alkyl group having 3 or more carbon atoms is preferably a linear one. The upper limit of the number of carbon atoms of the alkyl group having 3 or more carbon atoms is not particularly limited, but is usually preferably 30 or less, more preferably 25 or less, still more preferably 20 or less.

The polishing composition containing ammonium (A) can be preferably prepared by using the corresponding hydroxide or a salt thereof. A person containing crystal water may also be used as the above hydroxide or a salt thereof. The type of the anion constituting the above salt is not particularly limited, and the organic anion may be an inorganic anion. Examples of the inorganic anion are exemplified by F ^- , Cl ^- , Br ^- , I ^- , ClO ₄ ^- , BH ₄ ^- and the like. Usually, a hydroxide of ammonium (A) or a salt of ammonium (A) and an inorganic anion is preferably used. Among them, the hydroxide of ammonium (A) is preferred.

Another method of preparing the polishing composition containing ammonium (A) is, for example, a method in which a halogenated salt of ammonium (A) and an alkali metal hydroxide are coexisted.

The content of the ammonium (A) is, for example, 0.05 parts by mass or more based on 100 parts by mass of the abrasive grains, based on the amount of the hydroxide of the ammonium (A). The content of the ammonium (A) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, based on 100 parts by mass of the abrasive grains. Too much ammonium (A) also tends to reduce the polishing rate. Therefore, the content of the ammonium (A) is usually 20 parts by mass or less based on 100 parts by mass of the abrasive grains, preferably 15 parts by mass or less, more preferably 10 parts by mass or less. In a preferred embodiment, the content of the ammonium (A) may be 0.5 to 5 parts by mass based on 100 parts by mass of the abrasive grains, and may be, for example, 1 to 4 parts by mass. From the viewpoint of improving the balance between the polishing rate and the turbidity reduction, in another aspect, the content of the ammonium (A) may be 1 to 5 parts by mass (more preferably 2 to 5 parts by mass based on 100 parts by mass of the abrasive grains). It is preferably 2.5 to 5 parts by mass, for example, 3.5 to 5 parts by mass).

<water>

The water constituting the polishing composition disclosed herein preferably uses ion-exchanged water (deionized water), pure water, ultrapure water, distilled water or the like. In order to avoid as much as possible the effect of blocking other components contained in the polishing composition, the water to be used is preferably, for example, a total content of transition metal ions of 100 ppb or less. For example, the impurity ion can be removed by an ion exchange resin, the foreign matter can be removed by filtration, and the purity of the water can be increased by distillation or the like.

The polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) which can be uniformly mixed with water, as needed. usually, More preferably, 90% by volume or more of the solvent contained in the polishing composition is water, and more preferably 95% by volume or more (typically 99 to 100% by volume) is water.

The polishing composition disclosed herein (typically a slurry-like composition) may preferably have a solid content (non-volatile content; NV) of, for example, 0.01% by mass to 50% by mass, The remainder is in the form of an aqueous solvent (water or a mixed solvent of water and the above organic solvent), or the remainder is in the form of an aqueous solvent and a volatile compound such as ammonia. More preferably, the above NV is in a form of 0.05% by mass to 40% by mass. In addition, the solid content (NV) is determined by the ratio of the mass of the residue after the polishing composition is dried at 105 ° C for 24 hours in the polishing composition.

<Water-soluble polymer>

The polishing composition disclosed herein may contain a water-soluble polymer as an optional component. The kind of the water-soluble polymer is not particularly limited and may be appropriately selected from water-soluble polymers known in the field of polishing compositions. The water-soluble polymer may be used singly or in combination of two or more.

The water-soluble polymer may be one having at least one functional group selected from the group consisting of a cationic group, an anionic group, and a nonionic group in the molecule. The water-soluble polymer may have, for example, a hydroxyl group, a carboxyl group, a decyloxy group, a sulfo group, a first-order guanamine structure, a heterocyclic structure, a vinyl structure, or a polyoxyalkylene structure. From the viewpoint of reduction in agglomerates or improvement in detergency, a nonionic polymer can be preferably used as the water-soluble polymer.

Examples of the polymer which can be preferably used in the polishing composition disclosed herein are cellulose derivatives, starch derivatives, polymers of oxygen-containing alkylene units, polymers containing nitrogen atoms, polyvinyl alcohol, and the like. .

Specific examples of the cellulose derivative are hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, methylcellulose, ethylcellulose, ethylhydroxyl Ethyl cellulose, carboxymethyl cellulose, and the like. Among them, hydroxyethyl cellulose is preferred.

Specific examples of the starch derivative are exemplified by gelatinized starch, pullulan, and cyclodextrin. Among them, the pullulan polysaccharide is preferred.

The oxygen-containing alkylene unit polymer is exemplified by polyethylene oxide (PEO) or block copolymer of ethylene oxide (EO) with propylene oxide (PO) or butylene oxide (BO), EO and a random copolymer of PO or BO, and the like. Among them, a block copolymer of EO and PO or a random copolymer of EO and PO is preferred. The block copolymer of EO and PO may be a diblock, a triblock or the like containing a PEO block and a polypropylene oxide (PPO) block. Examples of the above triblock include a PEO-PPO-PEO type triblock and a PPO-PEO-PPO type triblock. Generally, it is more preferably a PEO-PPO-PEO type triblock.

In the block copolymer or random copolymer of EO and PO, the molar ratio of EO to PO (EO/PO) constituting the copolymer is preferably larger than the viewpoint of solubility in water or detergency. 1, more preferably 2 or more, and even more preferably 3 or more (for example, 5 or more).

The polymer containing a nitrogen atom may use a polymer having a nitrogen atom in the main chain and a polymer having a nitrogen atom on a side chain functional group (pendent group). Any of them. Examples of the polymer having a nitrogen atom in the main chain are exemplified by homopolymers and copolymers of N-fluorenylalkyleneimine type monomers. Specific examples of the N-fluorenylalkyleneimine type monomer are N-ethenylethylideneamine, N-propylmercaptoethylamine, and the like. The polymer having a nitrogen atom on the side group is exemplified by a polymer containing a monomer unit of an N-vinyl type or the like. For example, homopolymers and copolymers of N-vinylpyrrolidone and the like can be used.

When polyvinyl alcohol is used as the water-soluble polymer, the degree of saponification of the polyvinyl alcohol is not particularly limited.

The molecular weight of the water-soluble polymer in the polishing composition disclosed herein is not particularly limited. The weight average molecular weight (Mw) of the water-soluble polymer may be, for example, 200 × 10 ⁴ or less, and usually 150 × 10 ⁴ or less, and is preferably 120 × 10 from the viewpoint of filterability or detergency of the polishing composition. ⁴ or less, more preferably 100 × 10 ⁴ or less, and even more preferably 50 × 10 ⁴ or less. Further, from the viewpoint of improving surface protection after polishing, a water-soluble polymer having a Mw of 1 × 10 ⁴ or more is usually preferably used.

The relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the water-soluble polymer is not particularly limited. From the viewpoint of preventing generation of aggregates and the like, for example, the molecular weight distribution (Mw/Mn) is preferably 10.0 or less, more preferably 7.0 or less.

Further, the Mw and Mn of the water-soluble polymer may be a value based on a water-based gel permeation chromatography (GPC) (water system, polyethylene oxide equivalent).

The content of the water-soluble polymer may be, for example, 0.01 parts by mass or more based on 100 parts by mass of the abrasive particles. Water soluble The content of the polymer is preferably 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.5 mass, from the viewpoint of improving the surface smoothness (for example, reduction of turbidity) after polishing with respect to 100 parts by mass of the abrasive grains. Parts or more (for example, 1 part by mass or more). In addition, the content of the water-soluble polymer may be, for example, 40 parts by mass or less, and usually 20 parts by mass or less, preferably 15 parts by mass, based on 100 parts by mass of the abrasive grains, from the viewpoints of polishing rate and detergency. The amount is preferably 10 parts by mass or less.

<alkaline compound>

The polishing composition disclosed herein may contain, as an optional component, a basic compound (excluding a hydroxide of ammonium (A) and a salt thereof) for adjusting pH or the like.

As the basic compound, a nitrogen-containing organic or inorganic basic compound, an alkali metal or alkaline earth metal hydroxide, various carbonates or hydrogencarbonates, or the like can be used. For example, it is a hydroxide of an alkali metal, ammonia, an amine, etc. Specific examples of the alkali metal hydroxide are exemplified by potassium hydroxide, sodium hydroxide and the like. Specific examples of the carbonate or hydrogencarbonate are ammonium hydrogencarbonate, ammonium carbonate, potassium hydrogencarbonate, potassium carbonate, sodium hydrogencarbonate, sodium carbonate, and the like. Specific examples of the amine are exemplified by methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylene Diamine, di-ethyltriamine, tri-ethyltetramine, anhydrous piperidine, piperidine hexahydrate, 1-(2-aminoethyl)piperidine, N-methylpiperidine, hydrazine, imidazole Or triazole or the like azole or the like. Other examples are exemplified as hydroxides of the ammonium grade 4 which are not equivalent to ammonium (A) or salts thereof. These basic compounds can be single It is used alone or in combination of two or more.

When the basic compound is used, the amount thereof can be appropriately set within a range that does not greatly impair the effects of the present invention. In a preferred embodiment, the concentration of the basic compound Mb (% by mass) may be set to be slightly lower than the content Ma (% by mass) in terms of the hydroxide of the ammonium (A) in the polishing composition. The amount of the compound used. That is, it is preferable to satisfy the polishing composition of Mb/Ma<1. According to this, the effect of containing ammonium (A) in the polishing composition can be exhibited more. Based on this viewpoint, it is preferred that Mb/Ma<0.5, more preferably Mb/Ma<0.3, and even more preferably Mb/Ma≦0.2. Alternatively, a basic compound as the optional component may not be substantially used from the viewpoint of simplification of the composition and the like. According to the polishing composition disclosed herein, as shown in the examples described later, a high polishing rate can be achieved even without containing a basic compound as the above optional component.

<Surfactant>

The polishing composition disclosed herein may contain a surfactant (typically a water-soluble organic compound having a molecular weight of less than 1 × 10 ⁴ ) as an optional component. By using a surfactant, the dispersion stability of the polishing composition can be improved. In addition, the turbidity of the polished surface can be easily reduced. The surfactants may be used alone or in combination of two or more.

As for the surfactant, those which are anionic or nonionic are preferred. More preferably a nonionic surfactant based on the viewpoint of low foaming or ease of pH adjustment. Listed as an oxygen-extended alkyl polymer such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.; polyoxyalkylene oxide Ether, polyoxyethylene ethyl phenyl ether, polyoxyethylene ethyl amine, polyoxyethyl alcohol ester, polyoxyethylene ethyl glyceryl ether fatty acid ester, polyoxyethylene ethyl sorbitol A polyoxyalkylene alkyl adduct of an alcoholic acid fatty acid ester or the like; a nonionic interface of a plurality of copolymers of an oxygen alkyl group (diblock type, triblock type, random type, interactive type) Active agent.

Specific examples of the nonionic surfactant are exemplified by block copolymers of EO and PO (diblock, PEO-PPO-PEO type triblock, PPO-PEO-PPO type triblock, etc.), Random copolymer of EO and PO, polyoxyethylene glycol, polyoxyethylene ethyl propyl ether, polyoxyethylene ethyl butyl ether, polyoxyethylene ethyl pentyl ether, polyoxyethylene ethyl hexyl ether, Polyoxyethylene ethyl octyl ether, polyoxyethylene ethyl-2-ethylhexyl ether, polyoxyethylene ethyl decyl ether, polyoxyethylene ethyl decyl ether, polyoxyethylene ethyl isodecyl ether, Polyoxyethylene ethyltridecyl ether, polyoxyethylene ethyl lauryl ether, polyoxyethylene ethyl cetyl ether, polyoxyethylene ethyl stearyl ether, polyoxyethylene ethyl stearyl ether , polyoxyethylene ethyl oleyl ether, polyoxyethylene ethyl phenyl ether, polyoxyethyl octyl phenyl ether, polyoxyethyl phenyl ether, polyoxyethylene ethyl dodecyl Phenyl ether, polyoxyethylene ethyl styrenated phenyl ether, polyoxyethylene ethyl laurylamine, polyoxyethylene ethyl stearylamine, polyoxyethyl oleylamine, polyoxyethylene Lipid amide, polyoxyethylene ethyl decylamine, polyoxyethylene ethyl laurate, polyoxygen Ethyl monostearate, polyoxyethylene ethyl distearate, polyoxyethylidene monooleate, polyoxyethylene ethyl dioleate, polylaurate polyethyl sorbitol Anhydride, monopalmitic acid polyoxyethylene ethyl sorbitan, monostearic acid polyoxyethylene sorbitan, monooleic acid polyoxyethylene sorbitan, trioleic acid polyoxyethylene Sorbitol, tetraoleic acid polyoxyethylene Pearitol, polyoxyethylene ethyl castor oil, polyoxyethylene ethyl hardened castor oil, and the like. Among the preferred surfactants are listed as block copolymers of EO and PO (especially, triblocks of PEO-PPO-PEO type), random copolymers of EO and PO, and polyoxyethylene ethyl ethers ( For example, polyoxyethylene ethyl decyl ether).

The molecular weight of the surfactant is typically less than 1 × 10 ⁴ , and is preferably 9,500 or less from the viewpoint of the filterability of the polishing composition or the detergency of the object to be polished. Further, the molecular weight of the surfactant is typically 200 or more, and is preferably 250 or more, more preferably 300 or more (for example, 500 or more) from the viewpoint of a turbidity reduction effect or the like. Further, the molecular weight of the surfactant may be a weight average molecular weight (Mw) obtained by GPC (aqueous, in terms of polyethylene glycol) or a molecular weight calculated from a chemical formula.

The preferred range of molecular weight of the surfactant may also vary depending on the type of surfactant. For example, when a block copolymer of EO and PO is used as the surfactant, the Mw is preferably 1,000 or more, more preferably 2,000 or more, and still more preferably 5,000 or more.

The content of the surfactant is, for example, 20 parts by mass or less based on 100 parts by mass of the abrasive grains, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less (for example, 6 parts by mass or less). The content of the surfactant is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, and more preferably 0.01 parts by mass or more, based on 100 parts by mass of the abrasive particles, from the viewpoint of more effective use of the surfactant. , 0.1 parts by mass or more).

Or, based on the simplification of composition, the polishing resistance disclosed herein The product can also be implemented in a manner that is substantially free of surfactant.

<Other ingredients>

The polishing composition disclosed herein may further contain a chelating agent, an organic acid, an organic acid salt, an inorganic acid, an inorganic acid salt, a preservative, an antifungal agent, etc., as long as it does not significantly impair the effects of the present invention. A conventional additive for a polishing composition (typically a polishing composition for final polishing of a tantalum wafer).

Examples of the chelating agent are an aminocarboxylic acid-based chelating agent and an organic phosphonic acid-based chelating agent. Examples of the aminocarboxylic acid-based chelating agent include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrogen triacetic acid, sodium nitrotriacetate, ammonium nitroacetate, hydroxyethylethylenediaminetriacetic acid, and hydroxyl group. Sodium ethylethylenediaminetriacetate, diethylenediaminepentaacetic acid, sodium diethylammonium pentaacetate, triethylammonium hexaacetate, and sodium triethylammonium hexaacetate. Examples of the organic phosphonic acid chelating agent include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotris(methylenephosphonic acid), ethylenediamine oxime (Asian) Methylphosphonic acid), di-extension ethyltriamine penta (methylene phosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1- Hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methane hydroxyphosphonic acid, 2-phosphonium butane-1,2-dicarboxylic acid, 1-phosphonium butane-2,3,4-tricarboxylic acid and α-methylphosphonium succinic acid. Among these, an organic phosphonic acid-based chelating agent is preferred, and among them, preferred are ethylenediamine oxime (methylene phosphonic acid) and di-ethyltriamine penta (methylene phosphonic acid). The most preferred chelating agent is exemplified by ethylenediamine oxime (methylene phosphonic acid).

Examples of the organic acid are fatty acids such as formic acid, acetic acid, and propionic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, and organic substances. Sulfonic acid, organic phosphonic acid, and the like. Examples of the organic acid salt are exemplified by alkali metal salts (sodium salts, potassium salts, etc.) or ammonium salts of organic acids. Examples of the inorganic acid are sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, and the like. Examples of the inorganic acid salt are exemplified by alkali metal salts (sodium salts, potassium salts, etc.) or ammonium salts of inorganic acids. The organic acid and the salt thereof, and the inorganic acid and the salt thereof may be used alone or in combination of two or more.

Examples of the preservative and the antifungal agent are an isothiazoline compound, a paraben, a phenoxyethanol, and the like.

<use>

The polishing composition disclosed herein can be applied to the grinding of abrasive objects having various materials and shapes. The shape of the object to be polished is not particularly limited. The polishing composition disclosed herein can be preferably applied to polishing of a flat object to be polished, such as a plate or a polyhedron.

The material of the object to be polished may be a metal or a semimetal such as tantalum, aluminum, nickel, tungsten, copper, tantalum, titanium or stainless steel, or an alloy thereof; quartz glass, aluminosilicate glass, glassy carbon, etc. Glassy substance; ceramic material such as alumina, ceria, sapphire, tantalum nitride, tantalum nitride, titanium carbide; compound semiconductor substrate materials such as tantalum carbide, gallium nitride, gallium arsenide; resin such as polyimide resin Materials, etc. It may be an object to be polished which is composed of a plurality of materials of the above. Among them, it can be applied to polishing of an object to be polished having a surface formed of tantalum. The technology disclosed in this article is an example For example, the cerium oxide-containing particles are used as a polishing composition for abrasive grains (typically, the cerium oxide-containing particles are used as a polishing composition for polishing particles), and the polishing composition is preferably a polishing composition. Application.

The polishing composition disclosed herein can be preferably applied to the final polishing of an object to be polished. Therefore, according to the present specification, a method of producing an abrasive including a final polishing step using the above-described polishing composition (for example, a method of manufacturing a tantalum wafer) is provided. Further, the term "final polishing" refers to the final polishing step in the manufacturing process of the target (that is, the step of no further polishing after the step). The polishing compositions disclosed herein can also be used in polishing steps that are upstream upstream of the final polishing. Here, the polishing step upstream of the final polishing refers to a pre-grinding step between the coarse grinding step and the final grinding step, typically including at least one polishing step, and further may include polishing twice, three times, etc. step. The polishing composition disclosed herein can be preferably used, for example, in a polishing step just prior to final polishing.

The polishing compositions disclosed herein are best used for the grinding of tantalum wafers. For example, a polishing composition used as a final polishing for a tantalum wafer or a polishing step further upstream thereof can be preferably used. For example, it can be effectively applied to polishing of a wafer (typically final polishing or polishing before it) of a surface state of a surface roughness of 0.01 nm to 100 nm modulated by an upstream step. It is best applied to the final polishing.

When the polishing composition disclosed herein is used in the polishing of the wafer, the value of the resistivity of the germanium wafer is not particularly limited. For example, the power group rate can be appropriately used up to 1.00 Ω. Cm wafers. Among them, it can be well applied to a resistivity of 0.1Ω which is generally called a low-resistance wafer. Below cm 矽 Wafer. The concept of low-resistance wafers referred to herein includes p+, p++, p+++, etc. germanium wafers. The low-resistance germanium wafer is typically reduced in resistivity by a dopant containing a greater amount of germanium, arsenic, or boron than usual, compared to a general resistivity of 1 to 100 Ω. The wafers around cm are highly resistant to chemical etching. Therefore, in the grinding of low-resistance wafers, it is quite difficult to increase the polishing rate. Alternatively, there is a possibility that the surface quality such as an increase in the surface haze value is greatly lowered when the polishing rate is increased. The polishing composition disclosed herein is also preferably applied to the low-resistance wafer, which can suppress the reduction in surface quality and can effectively increase the polishing rate. Therefore, the polishing composition disclosed herein can be suitably used in the polishing of various tantalum wafers including p+ type, p++ type, and the like. In particular, it is applied to a resistivity of 0.01 Ω. Significant effects can be achieved in wafers below cm.

<Slurry>

The polishing composition disclosed herein is typically supplied to a polishing object in the form of a polishing liquid containing the polishing composition, and is used for polishing the polishing object. The above slurry may be prepared, for example, by diluting (typically diluted with water) any of the polishing compositions disclosed herein. Alternatively, the polishing composition may be used as the polishing liquid as it is. That is, the concept of the polishing composition in the technique disclosed herein includes a polishing liquid (action slurry) for polishing the polishing object to be supplied to the object to be polished, and a concentrate (a slurry for dilution) used as a polishing liquid. Stock solution) both. As another example of the polishing liquid containing the polishing composition disclosed herein, a polishing liquid obtained by adjusting the pH of the composition is exemplified.

The content of the abrasive grains in the polishing liquid disclosed herein is not particularly limited, and is typically 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more. Higher grinding rates can be achieved by increasing the amount of abrasive particles. The content is usually 10% by mass or less, preferably 7% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, for example, 1 mass, from the viewpoint of achieving a surface having a lower turbidity. Below the %, the ammonium (A) content in the polishing liquid is not particularly limited. For example, it may be 0.00001% by mass or more of the polishing liquid in terms of the amount of the hydroxide of the ammonium (A). The content is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, and even more preferably 0.0025% by mass or more based on the polishing rate. The content may be set to 0.005% by mass or more. Further, even if the content of the ammonium (A) is too large, there is a tendency that the polishing rate is lowered. Therefore, the content is preferably 0.20% by mass or less, preferably 0.10% by mass or less, and more preferably 0.050% by mass or less. In a preferred embodiment, the content may be, for example, 0.0025 to 0.030% by mass.

The lower limit of the pH of the polishing liquid is preferably 8.0 or more, more preferably 9.0 or more, still more preferably 9.5 or more. When the pH of the polishing liquid is 8.0 or more (preferably 9.0 or more, more preferably 9.5 or more), the polishing rate of the ruthenium wafer can be improved, and the ruthenium wafer having high surface precision can be obtained efficiently. The pH upper limit of the polishing liquid is not particularly limited, but is preferably 12.0 or less, more preferably 11.0 or less. If the pH of the polishing liquid is 12.0 or less (more preferably 11.0 or less), the abrasive grains contained in the polishing liquid can be prevented (especially colloidal oxidation) The cerium oxide particles such as cerium, fumed cerium oxide, and precipitated cerium oxide are dissolved by the basic compound, and the mechanical polishing action by the abrasive grains can be suppressed from being lowered. The above pH can be suitably applied to a polishing liquid used for polishing a silicon wafer (for example, a polishing liquid for final polishing). The pH of the slurry can be obtained by using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (Model F-23) manufactured by Horiba, and using a standard buffer (phthalate pH buffer pH: 4.01). (25 ° C), neutral phosphate pH buffer pH: 6.86 (25 ° C), carbonate pH buffer pH: 10.01 (25 ° C)) After 3 points of calibration, the glass electrode was placed in the slurry, the measurement passed More than 2 minutes and the value of stability is mastered.

When the polishing composition disclosed herein contains a surfactant, the content of the surfactant in the polishing liquid is not particularly limited, and may be, for example, 1 × 10 ^-4 mass% or more. The content is preferably 5 × 10 ^-4 mass% or more, more preferably 1 × 10 ^-3 mass% or more, for example, 2 × 10 ^-3 mass% or more, from the viewpoint of reducing turbidity and the like. In addition, the content is preferably 0.2% by mass or less, more preferably 0.1% by mass or less (for example, 0.05% by mass or less), from the viewpoints of the detergency, the polishing rate, and the like.

<Concentrate>

The polishing composition disclosed herein may be in a concentrated form (that is, a concentrated liquid form of the polishing liquid) before being supplied to the object to be polished. The polishing composition in a concentrated form is advantageous from the viewpoints of convenience in production, distribution, storage, and the like, and cost reduction. The concentration ratio can be, for example, about 2 to 100 times in terms of volume, and usually 5 to 50 times left. right. The concentration ratio of the polishing composition in a preferred state is 10 to 40 times.

The polishing composition in the form of the concentrated liquid can be prepared by diluting the polishing liquid at a desired point, and supplying the polishing liquid to the object to be polished. The above dilution can be typically carried out by adding the aqueous solvent to the concentrate and mixing. In addition, when the aqueous solvent is a mixed solvent, only a part of the components of the aqueous solvent may be added and diluted, or may be added in a different amount from the aqueous solvent than the mixed solvent containing the components. Further, in the multi-dose polishing composition described later, one of the above-mentioned materials may be diluted and mixed with other chemicals to prepare a polishing liquid, or a plurality of kinds of chemicals may be mixed and the mixture may be diluted to prepare a polishing liquid.

The NV of the above concentrate may be, for example, 50% by mass or less. The NV of the concentrated liquid is preferably 40% by mass or less, preferably 30% by mass or less, more preferably 20%, based on the stability of the polishing composition (for example, the dispersion stability of the abrasive grains) or the filterability. The mass% or less is, for example, 15% by mass or less. Further, the NV of the concentrated liquid is preferably 0.5% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, for example, from the viewpoints of convenience in production, distribution, storage, etc., or cost reduction. 5 mass% or more.

The content of the abrasive grains in the concentrate may be, for example, 50% by mass or less. The content is usually preferably 45% by mass or less, more preferably 40% by mass or less, from the viewpoint of stability of the polishing composition (for example, dispersion stability of the abrasive grains) or filterability. Better state In addition, the content of the abrasive grains may be 30% by mass or less, or may be 20% by mass or less (for example, 15% by mass or less). In addition, the content of the abrasive grains can be, for example, 0.5% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoints of convenience in production, distribution, storage, etc., or cost reduction (for example, for example, 4% by mass or more).

The content of the ammonium (A) in the concentrate may be, for example, 0.001% by mass or more based on the amount of the hydroxide. The content is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and more preferably 0.05% by mass or more, from the viewpoints of convenience in terms of convenience in production, distribution, storage, and the like. In addition, it is preferable that the content is 5.0% by mass or less, preferably 2.0% by mass or less, and more preferably 1.0% by mass or less, from the viewpoints of the filterability and the detergency of the polishing composition. In a preferred embodiment, the above content may be set to 0.05 to 0.5% by mass.

The polishing composition disclosed herein may be in one dosage form or in a multiple dosage form represented by two dosage forms. For example, the liquid A containing one of the components of the polishing composition (typically, components other than the aqueous solvent) is mixed with the liquid B containing the remaining components to be used for polishing the object to be polished.

<Modulation of polishing composition>

The method for producing the polishing composition disclosed herein is not particularly limited. For example, each component contained in the polishing composition can be mixed using a conventional mixing device such as a wing mixer, an ultrasonic disperser, or a homomixer. mixing The form of the components is not particularly limited. For example, all components may be mixed at once, or may be mixed in an appropriately set order.

<grinding>

The polishing composition disclosed herein can be preferably used for the grinding of the object to be polished, for example, in the following manner. Hereinafter, a preferred embodiment of the method of polishing the object to be polished using the polishing composition disclosed herein will be described.

That is, a polishing liquid (typically a slurry-like polishing liquid, sometimes referred to as an abrasive slurry) containing any of the polishing compositions disclosed herein is prepared. When the polishing liquid is prepared, the polishing composition may be prepared by applying a concentration adjustment (for example, dilution) or a pH adjustment to the polishing composition. Alternatively, the polishing composition described above can be used as a polishing liquid as it is. Further, in the case of a multi-dosage polishing composition, when the polishing liquid is prepared, it may include mixing the chemicals, diluting 1 or a plurality of chemicals before the mixing, and diluting the mixture after the mixing.

Next, the polishing liquid is supplied to the object to be polished, and is ground by a usual method. For example, when the final polishing of the germanium wafer is performed, the germanium wafer subjected to the polishing step and the pre-polishing step is fixed on a general polishing device, and the polishing liquid is supplied to the surface of the germanium wafer by the polishing pad of the polishing device (polishing object) surface). Typically, the liner is continuously supplied with the slurry while pressing the polishing pad against the surface of the crucible wafer and relatively moving (e.g., rotationally moving). The polishing of the object to be polished is completed by the polishing step.

Moreover, the polishing pad used in the above polishing step is not particularly limited. For example, any of a non-woven type, a felt type, a type containing abrasive grains, and a type containing no abrasive grains can be used.

<washing>

Abrasives that are ground using the polishing compositions disclosed herein are typically washed after milling. This washing can be carried out using a suitable washing liquid. The cleaning liquid to be used is not particularly limited, and a general SC-1 cleaning solution (ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ), and water (H ₂ ) in the field of, for example, a semiconductor can be used. A mixture of O), SC-2 washing solution (a mixture of HCl and H ₂ O ₂ and H ₂ O). The temperature of the washing liquid can be, for example, about room temperature to about 90 °C. From the viewpoint of improving the washing effect, it is preferred to use a washing liquid of about 50 ° C to 85 ° C.

In the following, several embodiments of the present invention are described, but the present invention is not intended to be limited to the embodiments shown. In addition, in the following description, "parts" and "%" are quality standards unless otherwise specified.

<Modulation of polishing composition> (Example 1)

The abrasive grains, tetrabutylammonium hydroxide (TBAH; butyl are linear butyl groups), hydroxyethyl cellulose (HEC), and deionized water were mixed to prepare a concentrate of the polishing composition. The concentrate was diluted to 20 times with deionized water to prepare a polishing composition of this example.

As the abrasive granules, colloidal cerium oxide having an average primary particle diameter D _P1 of 35 nm and an average secondary particle diameter D _P2 of 66 nm was used. The above average particle diameter was measured by a surface area measuring device manufactured by Micromeritics Co., Ltd., and the product name was "Flow Sorb II 2300". Further, the above secondary average particle diameter is a volume average secondary particle diameter measured by a model "UPA-UT151" manufactured by Nikkiso Co., Ltd.

The HEC system used Mw of 120 × 10 ⁴ .

The amount of the abrasive grains, TBAH, and HEC used was such that the content of the abrasive grains in the polishing composition was 0.46%, the content of TBAH was 0.010%, and the content of HEC was 0.012%. The pH of the polishing composition was 9.9.

In this example, the ratio of the TBAH content to the abrasive grain content in the polishing composition (hereinafter referred to as "TBAH/abrasive grain") was 2.17%.

(Example 2)

The polishing composition of this example was prepared in the same manner as in Example 1 except that the amount of use of TBAH was changed so that the content of the polishing composition was 0.015%.

The polishing composition of this example (TBAH/abrasive grain) was 3.26%.

(Example 3)

The polishing composition of this example was prepared in the same manner as in Example 1 except that the amount of use of TBAH was changed so that the content in the polishing composition was 0.020%.

The polishing composition of this example (TBAH/abrasive grain) was 4.35%.

(Example 4)

Except for the 50 × 10 ⁴ Mw were as HEC, while the content of abrasive grains in the polishing composition becomes 0.11%, 0.005% content of TBAH become mode changing amount of the abrasive grains and TBAH except I Example 1 Also, the polishing composition of this example was prepared.

The polishing composition of this example (TBAH/abrasive grain) was 4.55%.

(Example 5)

Further addition of ammonia polishing using the composition of (NH ₃₎ becomes an amount of 0.001% content of ammonia water (29% concentration) except that in Example 4 the same I to prepare polishing compositions of the present embodiment.

The polishing composition of this example (TBAH/abrasive grain) was 4.55%.

(Comparative Example 1)

In this example, tetramethylammonium hydroxide (TMAH) was used in an amount of 0.013% in the composition for polishing instead of TBAH. Otherwise, in the same manner as in Example 1, the polishing composition of this example was prepared.

(Comparative Example 2)

The polishing composition of this example was prepared in the same manner as in Comparative Example 1, except that the amount of the HEC used was changed so that the content of the polishing composition was 0.001%.

(Comparative Example 3)

The polishing composition of this example was prepared in the same manner as in Comparative Example 1, except that HEC was not used.

(Comparative Example 4)

In this example, tetraethylammonium hydroxide (TEAH) in an amount of 0.010% in the composition for polishing was used in place of TBAH. Otherwise, in the same manner as in Example 1, the polishing composition of this example was prepared.

(Comparative Example 5)

The abrasive grains, potassium hydroxide (KOH), HEC, and deionized water were mixed to prepare a concentrate of the polishing composition. The concentrate was diluted to 20 times with deionized water to prepare a polishing composition of this example.

The abrasive grains and the HEC system were the same as in Example 1.

The amount of the abrasive grains, KOH, and HEC used was such that the content of the abrasive grains in the polishing composition was 0.46%, the KOH content was 0.023%, and the HEC content was 0.012%. The pH of the polishing composition was 10.6.

(Comparative Example 6)

The polishing composition of this example was prepared in the same manner as in Comparative Example 5 except that the amount of the HEC used was changed so that the content in the polishing composition was 0.001%.

(Comparative Example 7)

In this example, ammonia water (concentration: 29%) in an amount of 0.027% of ammonia (NH ₃ ) in the polishing composition was used instead of KOH. Otherwise, in the same manner as in Comparative Example 5, the polishing composition of this example was prepared.

<矽Wrap of Wafer>

The polishing composition of each example was directly used as a polishing liquid, and the surface of the object to be polished was polished under the following conditions. For the polishing target system, the following two kinds of tantalum wafers were pre-polished by using a polishing slurry (trade name "GLANZOX 2100" manufactured by Fujimi Incorporated) to adjust the surface roughness to 0.1 nm to 10 nm.

[矽 wafer] (Wafer 1)

150mm diameter, conductive P type, crystal orientation <100>, resistivity 0.002~0.005Ω. Cm wafer (low resistance wafer)

(Wafer 2)

150mm diameter, conductive P type, crystal orientation <100>, resistivity 1.00~100Ω. Cm wafer

[grinding conditions]

Grinding machine: Fujitsu Machinery Industry Co., Ltd., model "SPM-15"

Polishing pad: manufactured by Fujimi Incorporated, a felt polishing pad "Surfin 000FM"

Grinding load: 15kPa

Platen speed: 25rpm

Carrier disk revolution: 25rpm

Grinding fluid temperature: 20 ° C

Feeding speed of the slurry: 600mL/min

Grinding time

Wafer 1:30 minutes

Wafer 2: 15 minutes

The polished silicon wafer was washed with SC-1 cleaning solution. More specifically, the first cleaning tank and the second cleaning tank of the ultrasonic oscillator having a frequency of 750 kHz are prepared, and the first cleaning tank accommodates the SC-1 washing liquid and is maintained at 80 ° C. The second cleaning tank contained deionized water and was kept at 23 °C. The polished silicon wafer was immersed in the first cleaning tank for 3 minutes, immersed in the second cleaning tank for 3 minutes, and immersed in the second cleaning tank in a state in which the ultrasonic oscillator was operated.

<Measurement of polishing rate>

The quality of the wafer before polishing and the quality of the wafer after cleaning were measured, and the polishing rate (nm/min) was calculated based on the difference. The results obtained are shown in Tables 1 and 2.

<Measurement of turbidity>

The turbidity was measured using AMS-AWIS3110 (product name manufactured by ADE) for the surface of the wafer after the cleaning. The results obtained are shown in Table 1 and Table 2.

As shown in Tables 1 and 2, in the polishing of the wafer 1 (low-resistance wafer), the turbidity value can be ensured while using the polishing composition of Examples 1 to 3 containing ammonium (A) derived from TBAH. The surface smoothness of 0.10 ppm was not achieved, and the polishing composition of Comparative Example 5 using KOH was 1.5 times or more, and the polishing composition of Comparative Example 7 using ammonia was twice or more higher. Further, the polishing compositions of Examples 1 to 3 were able to ensure the surface smoothness of the turbidity value of less than 0.10 ppm, and the polishing of Comparative Example 1 using TMAH and Comparative Example 4 using TEAH. The composition is a significantly higher polishing rate from 4 times to 20 times.

By using the polishing compositions of Examples 1 to 3 to reduce the amount of abrasive grains and TBAH, and the polishing compositions of Examples 4 and 5 containing lower molecular weight HEC, the surface having a haze value of less than 0.10 ppm can be ensured. The polishing rate was as high as about 1.4 times or more of Comparative Example 5 and Comparative Example 7, and about 3.5 times or more of Comparative Example 1 and Comparative Example 4, while achieving smoothness.

On the other hand, in the polishing composition of Comparative Example 6 in which the HEC content was reduced from the polishing composition of Comparative Example 5 and the polishing rate was improved, the haze value was maintained in the same manner as in Comparative Example 5, but the polishing rate was rather lowered. The polishing composition of Comparative Example 2 in which the polishing composition of Comparative Example 1 was reduced in HEC content was maintained in the same manner as in Comparative Example 1, but the polishing rate was not confirmed to be improved. The polishing composition of Comparative Example 3 in which the HEC was removed from the polishing composition of Comparative Example 1 showed an increase in the polishing rate, but the haze value was remarkably increased.

In the polishing of the wafer 2, when the polishing composition of Examples 1 to 3 using TBAH was used, the surface smoothness of the turbidity value of less than 0.10 ppm was ensured, and Comparative Example 5 and Comparative Example 7 were realized. A polishing rate of 1.2 to 5 times the polishing composition. Further, the polishing compositions of Examples 1 to 3 were able to obtain a polishing composition having a haze value of less than 0.10 ppm, and obtained a polishing composition of about 3 times as compared with the polishing compositions of Comparative Example 1 and Comparative Example 4. 10 times significantly higher grinding rate. In addition, when the polishing composition of Examples 4 and 5 using TBAH was used, it was possible to achieve about 1.15 times or more of Comparative Example 5 and Comparative Example 7 while ensuring the surface smoothness of the turbidity value of less than 0.10 ppm. 1 and Comparative Example 4 have a high polishing rate of about 2.5 times or more. Here, from the comparison between Example 4 and Example 5, it is understood that the polishing composition having a small amount of NH ₃ added in addition to TBAH tends to increase the polishing rate.

On the other hand, in the polishing composition of Comparative Example 2, which was obtained by reducing the content of HEC from the polishing composition of Comparative Example 1, and the polishing rate was improved, the polishing rate was improved as compared with Comparative Example 1, but the turbidity was improved. The value is significantly increased. The polishing composition of Comparative Example 3 in which the HEC was removed from the polishing composition of Comparative Example 1 had a more remarkable increase in the haze value. Further, in the polishing composition of Comparative Example 6 in which the polishing composition of Comparative Example 5 was reduced in HEC content, the polishing rate was higher than that of Comparative Example 5, but the haze value was also remarkably increased.

By including such an organic group having a substituent on the nitrogen atom of only 2 or less carbon atoms or an organic group having 3 or more carbon atoms, it is confirmed that the surface quality can be maintained and the polishing rate which can be achieved is remarkably poor. That is, the polishing composition of Examples 1 to 5 using TBAH having four alkyl groups having 4 carbon atoms as the above substituents can have a large polishing rate. Improve, and can suppress the decline of surface quality. On the other hand, the polishing composition of Comparative Examples 1 to 4 using TMAH having the carbon number of the alkyl group described above or TEAH having 2 carbon atoms in the alkyl group cannot have both high surface quality and high polishing. rate.

The specific examples of the present invention have been described in detail above, but are not intended to limit the scope of the patent application. The technology described in the patent application scope includes various modifications and changes of the specific examples described above.

Claims (7)

A polishing composition comprising abrasive grains, water, and a 4-grade ammonium cation represented by the following formula (A): (wherein R ¹ , R ² , R ³ and R ⁴ are the same or different and are each an organic group, at least one of which is an organic group having 3 or more carbon atoms). The polishing composition according to claim 1, wherein R ¹ , R ² , R ³ and R ⁴ in the above formula (A) are the same or different and each is a hydrocarbon group. The polishing composition according to claim 1 or 2, wherein R ¹ , R ² , R ³ and R ⁴ in the above formula (A) are the same or different and each is an alkyl group having 3 or more carbon atoms. The polishing composition according to any one of claims 1 to 3, wherein the abrasive grains are cerium oxide particles. The polishing composition according to any one of claims 1 to 4, further comprising a water-soluble polymer. The polishing composition according to any one of claims 1 to 5, which is used for polishing a tantalum wafer. A method for producing a polishing composition, which comprises preparing a polishing composition comprising abrasive grains, water, and a 4-stage ammonium cation represented by the following formula (A): (wherein R ¹ , R ² , R ³ and R ⁴ are the same or different and are each an organic group, at least one of which is an organic group having 3 or more carbon atoms).