TW201726880A - Polishing composition - Google Patents

Abstract

To provide a polishing composition that has a large ratio of polishing speed of polysilicon and amorphous silicon to polishing speed of silicon nitride, and has a high polishing speed of polysilicon and amorphous silicon, and that has a low polishing speed of silicon nitride. The polishing composition contains abrasive-grains, a quaternary ammonium salt having a benzene ring in the structure, and at least one of a water-soluble polymer and a surfactant. This polishing composition is used for polishing an object to be polished having at least one of polysilicon and amorphous silicon, and silicon nitride.

Description

Grinding composition

The present invention relates to a composition for polishing.

When the surface of the semiconductor substrate is planarized by chemical mechanical polishing (CMP), a tantalum nitride film which is relatively difficult to polish is disposed under the polycrystalline germanium film or the amorphous germanium film which is relatively easy to be polished. The ruthenium film is used as a stop layer to polish a polycrystalline ruthenium film or an amorphous ruthenium film. In such polishing, it is desirable to polish the polycrystalline germanium film or the amorphous germanium film with high efficiency, and hardly polish the tantalum nitride film.

Therefore, in the polishing composition used for such polishing, the ratio of the polishing rate of the polycrystalline germanium film and the amorphous germanium film to the polishing rate of the tantalum nitride film is required (by the polishing rate of the polycrystalline germanium film or the amorphous germanium film) In addition to the polishing rate of the tantalum nitride film, the polishing rate of the large, polycrystalline tantalum film and the amorphous germanium film is large, and the polishing rate of the tantalum nitride film is close to zero.

For example, Patent Document 1 discloses a polishing composition in which the ratio of the polishing rate of the polycrystalline germanium film to the polishing rate of the tantalum nitride film is large, and the polishing rate of the polycrystalline germanium film is large. However, the research disclosed in Patent Document 1 The polishing composition cannot be said that the polishing rate of the tantalum nitride film is sufficiently small. Therefore, after the polishing of the polycrystalline germanium film is completed, if the polishing operation is not completed accurately, the tantalum nitride film which is the stop layer is polished.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 266155

Therefore, the present invention solves the problems of the above-described conventional techniques, and an object of the invention is to provide a polishing composition which has a large ratio of a polishing rate of polycrystalline germanium and amorphous germanium to a polishing rate of tantalum nitride, and a polycrystalline germanium. The polishing rate of the amorphous germanium is large, and the polishing rate of the tantalum nitride is small.

In order to solve the above problems, a polishing composition according to an aspect of the present invention is used for polishing a polishing composition having at least one of polycrystalline germanium and amorphous germanium and a polishing target of tantalum nitride, and the object is to contain abrasive grains. And a quaternary ammonium salt having a benzene ring in the structure, at least one of a water-soluble polymer and a surfactant.

In the polishing composition of the present invention, the ratio of the polishing rate of the polycrystalline germanium and the amorphous germanium to the polishing rate of the tantalum nitride is large, the polishing rate of the polycrystalline germanium and the amorphous germanium is large, and the polishing rate of the tantalum nitride is small.

1‧‧‧矽 substrate

2‧‧‧Oxide film

3‧‧‧ nitride film

4‧‧‧Polysilicon film

4a‧‧ ‧ step

Fig. 1 is a cross-sectional view showing the structure of a germanium wafer.

[Formation of the Invention]

Hereinafter, an embodiment of the present invention will be described in detail. Furthermore, this embodiment shows an example of the present invention, and the present invention is not limited to the embodiment. Further, various modifications and improvements can be made to the embodiment, and such modifications or improvements can be included in the invention. For example, in the present embodiment, a polishing composition for polishing a polishing object having polycrystalline germanium or tantalum nitride is described. However, the polishing composition can also be used for polishing objects having amorphous germanium and tantalum nitride. Grinding or grinding of an object to be polished having polycrystalline germanium and amorphous germanium and tantalum nitride.

The polishing composition of the present embodiment is a polishing composition for polishing a polishing object having polycrystalline germanium and tantalum nitride, and contains abrasive grains, a quaternary ammonium salt having a benzene ring in the structure, and a water-soluble polymer. And at least one of the surfactants.

When the polishing composition of the present embodiment is polished under the same conditions, the polishing rate of the polycrystalline silicon is higher than the polishing rate of the tantalum nitride. The ratio (hereinafter also referred to as "grinding speed ratio") is large, and the polishing rate of polycrystalline silicon is large and the polishing rate of tantalum nitride is small. Further, when the object to be polished has an amorphous germanium, the word "polycrystalline germanium" can be replaced with the word "amorphous germanium" (the same applies hereinafter).

In detail, the polishing composition of the present embodiment can efficiently polish polycrystalline germanium because of its high hydrolyzability. Therefore, when the polishing composition of the present embodiment is used for polishing, the polishing rate of the polycrystalline silicon is increased. Further, the cation of the quaternary ammonium salt suppresses the polishing of the tantalum nitride by being adsorbed to the negatively charged tantalum nitride. Therefore, when polishing is performed using the polishing composition of the present embodiment, the polishing rate of tantalum nitride becomes small. Further, since the polishing rate of the polycrystalline crucible is kept large, the polishing rate ratio becomes large (that is, the selectivity of polishing is high), and the polishing rate ratio can be 250 or more.

Therefore, when the polishing target having the polycrystalline germanium and the tantalum nitride is polished by using the polishing composition of the present embodiment, the polycrystalline silicon can be efficiently and selectively polished and removed. Further, since tantalum nitride is difficult to be polished, the polishing amount of tantalum nitride is slightly small even if the polishing operation is not completed immediately after the completion of the polishing of the polycrystalline silicon. For example, when a tantalum wafer in which a film of a polycrystalline germanium film is deposited on a tantalum nitride film is an object to be polished, the polycrystalline germanium film can be efficiently and selectively polished and removed. Further, even if the polishing operation was not completed immediately after the completion of the polishing of the polysilicon film, the tantalum nitride film as the stopper layer was hardly polished.

Further, the water-soluble polymer has an action of adsorbing on polycrystalline germanium to suppress polishing. When there is a step on the surface of the polycrystalline crucible, the water-soluble polymer adsorbed on the convex portion constituting the step is removed by grinding. While maintaining the polishing rate of the polycrystalline silicon, on the other hand, the water-soluble polymer constituting the concave portion of the step is not removed and the polishing is suppressed. Therefore, when the polishing composition of the present embodiment is used for polishing, the polishing rate of the convex portion and the concave portion on the surface of the polycrystalline silicon is different, and as a result, the step of the surface of the polycrystalline silicon is easily relaxed.

Further, when a nitrogen-containing water-soluble polymer having nitrogen in its structure is used as the water-soluble polymer, the polishing rate of the convex portion is promoted, so that particularly good step relaxation performance can be obtained. It is believed that this is due to the presence of nitrogen atoms on the surface of the water-soluble polymer adsorbed on the surface of the polycrystalline silicon, due to the positive charge and hydrophilic action of the nitrogen atom, and the hydrophilic and negatively charged grinding. The affinity of the particles to the surface of the polycrystalline crucible is increased to promote scraping by the abrasive particles.

Hereinafter, the polishing composition of the present embodiment will be described in more detail.

1.About the object to be polished

In the polishing using the polishing composition of the present embodiment, the object to be polished is not particularly limited as long as it has polycrystalline germanium or tantalum nitride, and for example, a polycrystalline germanium film is formed on the surface of the substrate. Niobium nitride film. The material of the substrate is not particularly limited, and examples thereof include elemental ruthenium, ruthenium compound, metal, ceramic, and resin.

Examples of the elemental ruthenium include single crystal ruthenium, polycrystalline ruthenium (polycrystalline ruthenium), and amorphous ruthenium. Further, examples of the antimony compound include cerium nitride and cerium oxide (for example, tetraethoxy decane (TEOS) is used to form The ruthenium dioxide interlayer insulating film), tantalum carbide, and the like.

Further, examples of the metal include tungsten, copper, aluminum, ruthenium, cobalt, nickel, titanium, rhodium, gold, silver, platinum, palladium, rhodium, ruthenium, osmium, iridium, and the like. These metals may also be present in the form of alloys or metal compounds.

Specific examples of such an object to be polished include a tantalum wafer in which a film of a polycrystalline germanium film is deposited on a tantalum nitride film.

2. About abrasive grains

The type of the abrasive grains contained in the polishing composition of the present embodiment is not particularly limited, and may be, for example, any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include particles made of a metal oxide such as vermiculite, alumina, cerium oxide, or titanium oxide, and ceramics such as tantalum nitride, tantalum carbide, or boron nitride. particle. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles. These abrasive grains may be used singly or in combination of two or more.

Among these specific examples, vermiculite is preferred. Specific examples of the vermiculite include colloidal vermiculite, smoked vermiculite, and sol-gel vermiculite. Among these vermiculite, colloidal vermiculite is preferred, and colloidal vermiculite is used. More preferably, it is a colloidal vermiculite having a dome shape (for example, a shape of a rotating body obtained by rotating an ellipse around a long axis). Further, the organic acid may be immobilized on the surface of the vermiculite. The immobilization of the organic acid to the vermiculite is carried out by chemically bonding the functional group of the organic acid to the surface of the vermiculite. Examples of the organic acid include a sulfonic acid, a carboxylic acid, a sulfinic acid, and a phosphonic acid.

The content of the abrasive grains in the polishing composition can be 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 1% by mass or more. As the content of the abrasive grains increases, the removal rate (polishing speed) of the object to be polished by the polishing composition increases.

In addition, the content of the abrasive grains in the polishing composition can be 15% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2.3% by mass. the following. As the content of the abrasive grains is reduced, the material cost of the polishing composition can be suppressed, and aggregation of the abrasive grains is hard to occur.

The average primary particle diameter of the abrasive grains can be 5 nm or more, preferably 10 nm or more, and more preferably 30 nm or more. As the average primary particle diameter of the abrasive grains increases, the polishing rate of the object to be polished by the polishing composition increases.

Further, the average primary particle diameter of the abrasive grains can be 200 nm or less, preferably 100 nm or less, more preferably 50 nm or less. As the average primary particle diameter of the abrasive grains is reduced, the object to be polished is polished by using the polishing composition, whereby the surface to be polished having few surface defects is easily obtained.

Further, the value of the average primary particle diameter of the abrasive grains can be calculated, for example, based on the specific surface area of the abrasive grains measured by the BET method such as nitrogen. Further, in the case of non-spherical abrasive grains such as colloidal vermiculite, the average primary particle diameter of the pseudospherical particles is calculated based on the specific surface area of the abrasive grains measured by the BET method. The average primary particle diameter of the imaginary spherical particles is regarded as the average primary particle diameter of the non-spherical abrasive grains.

3. Regarding the quaternary ammonium salt having a benzene ring in the structure

In the polishing composition of the present embodiment, a quaternary ammonium salt having a benzene ring in the structure (hereinafter, simply referred to as "quaternary ammonium salt") is added. The type of the quaternary ammonium salt is not particularly limited as long as it has a benzene ring in its structure. For example, the ammonium ion of the quaternary ammonium salt is represented by the following Chemical Formula 1.

Further, x in the following Chemical Formula 1 is an integer of 1 or more and 15 or less, and y, z and w are each independently an integer of 0 or more and 4 or less. However, the smaller x, y, z, and w are, the better.

Examples of the quaternary ammonium salt having an ammonium ion represented by the above Chemical Formula 1 include benzyltrimethylammonium chloride and benzyltriethylammonium chloride shown in the following Chemical Formulas 2 to 4. Benzyltributylammonium chloride or the like.

In addition, examples of the quaternary ammonium salt having an ammonium ion other than those represented by the above Chemical Formula 1 include benzyldimethyltetradecyl ammonium chloride hydrate represented by the following Chemical Formulas 5 to 12, Benzyl dimethyl phenyl ammonium chloride, trimethyl phenyl ammonium chloride, triethyl phenyl ammonium chloride, benzethonium chloride, benzyl choline chloride, chlorination Benzalkonium chloride, denatonium benzoate, and the like.

These quaternary ammonium salts may be used singly or in combination of two or more.

Further, the quaternary ammonium salt shown in Chemical Formulas 2 to 12 is a salt of an ammonium ion and a chloride ion or a benzoic acid ion, but may be an ammonium ion and a hydroxide ion, a fluoride ion, a bromide ion, or an iodine. a salt of a compound ion or an organic acid ion.

Further, in order to increase the polishing rate of the polycrystalline silicon and the ratio of the polishing rate of the polycrystalline germanium to the polishing rate of the tantalum nitride, the ammonium ion of the quaternary ammonium salt is an ammonium ion of the quaternary ammonium salt represented by the other chemical formula. Better.

Further, as the anion of the quaternary ammonium salt, hydroxide ions are most preferable from the viewpoint of an anion residue on the surface after polishing.

The content of the quaternary ammonium salt in the polishing composition can be 0.0001% by mass or more, preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.03% by mass or more. As the content of the quaternary ammonium salt becomes higher, the polishing rate of the polycrystalline silicon due to the polishing composition and the ratio of the polishing rate of the polycrystalline germanium to the polishing rate of the tantalum nitride increase.

In addition, the content of the quaternary ammonium salt in the polishing composition can be 1% by mass or less, preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. Thereby, excellent step mitigation performance is obtained.

4. About water soluble polymer

At least one of a water-soluble polymer and a surfactant is added to the polishing composition of the present embodiment. The type of the water-soluble polymer is not particularly limited, and examples thereof include methyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxy group. Cellulose such as methyl cellulose, carboxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, or polysaccharides such as chitosan, or polyethylene glycol, polyethyleneimine, poly-N-ethylene A polymer such as pyrrolidone, polyvinyl alcohol, polyacrylic acid (or a salt thereof), polyacrylamide or polyethylene oxide. These water-soluble polymers may be used alone or in combination of two or more.

Among these water-soluble polymers, a nitrogen-containing water-soluble polymer having nitrogen in its structure is preferred. The number of nitrogen atoms of the nitrogen-containing water-soluble polymer monomer may be one or plural. Further, the nitrogen-containing water-soluble polymer may have a nitrogen atom in its main chain or a nitrogen atom in its side chain. Further, the nitrogen-containing water-soluble polymer may have a nitrogen atom as an amine group, an imine group, a guanamine group, a guanidinium group, a carbodiimide group, a fluorenyl group or a urethane group.

Further, the nitrogen-containing water-soluble polymer may have a nitrogen atom as a salt (for example, an ammonium salt) formed of a nitrogen cation and another anion. Examples of the nitrogen-containing water-soluble polymer having a salt structure include polycondensation polyamides such as water-soluble nylon, polycondensation polyesters such as water-soluble polyesters, polyaddition polyamines, and polyadditions. a polyimine, a polyaddition system (meth) acrylamide, a water-soluble polymer having a nitrogen atom in at least a part of an alkyl chain, a water-soluble polymer having a nitrogen atom in at least a part of a side chain, and the like .

Specific examples of the nitrogen-containing water-soluble polymer of the polyaddition system include polyvinylimidazole, polyvinylcarbazole, poly-N-vinylpyrrolidone, polyvinyl caprolactone, and polyvinyl group. Piperidine. Further, the nitrogen-containing water-soluble polymer may partially have a hydrophilic structure such as a vinyl alcohol structure, a methacrylic acid structure, a vinyl sulfonic acid structure, a vinyl alcohol carboxylate structure, or an oxyalkylene structure. Further, it may be a polymer having a structure of a plurality of such diblock type or triblock type, random type, or alternating type.

Further, the nitrogen-containing water-soluble polymer may be one in which one or all of the molecules have a cation, an anion, an anion and a cation, and a nonionic one.

Among these nitrogen-containing water-soluble polymers, poly-N-vinylpyrrolidone, polyethyleneimine, and polypropylene decylamine are more preferred.

The weight average molecular weight of the water-soluble polymer can be 5,000 or more, preferably 10,000 or more, more preferably 30,000 or more, and still more preferably 40,000 or more. Thereby, the polishing rate of the polycrystalline silicon due to the polishing composition and the polishing rate of the polycrystalline silicon are increased with respect to the polishing rate of the tantalum nitride.

Further, the weight average molecular weight of the water-soluble polymer can be 3,000,000 or less, preferably 1,000,000 or less, more preferably 100,000 or less, and still more preferably 60,000 or less. Thereby, excellent step mitigation performance is obtained.

In addition, the content of the water-soluble polymer in the polishing composition can be 0.0001% by mass or more, preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.03% by mass or more. Thereby, excellent step mitigation performance is obtained.

In addition, the content of the water-soluble polymer in the polishing composition can be 1% by mass or less, preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and still more preferably 0.1% by mass or less. Thereby, the polishing rate of the polycrystalline silicon due to the polishing composition and the polishing rate of the polycrystalline silicon are increased with respect to the polishing rate of the tantalum nitride.

Further, the ratio of the content of the water-soluble polymer in the polishing composition to the content of the abrasive grains ([content of abrasive grains] / [content of water-soluble polymer]) may be 250 or less, preferably 150. Hereinafter, it is more preferably 100 or less, and particularly preferably 50 or less.

Also, the content of the water-soluble polymer in the polishing composition is four The ratio of the content of the ammonium salt (the content of the [quaternary ammonium salt] / the content of the water-soluble polymer] can be 1 or more, preferably 2 or more.

5. About surfactants

At least one of a water-soluble polymer and a surfactant is added to the polishing composition of the present embodiment. As the surfactant, any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be used.

Specific examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, polyoxyethylene alkyl sulfate, alkyl sulfate, polyoxyethylene alkyl sulfate, alkyl sulfuric acid, alkylbenzenesulfonic acid, and alkyl group. Phosphate ester, polyoxyethylene alkyl phosphate, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, or a salt thereof (eg, laurel Ammonium sulphate).

Further, specific examples of the cationic surfactant include an alkyltrimethylammonium salt, an alkyldimethylammonium salt, an alkylbenzyldimethylammonium salt, and an alkylamine salt.

Further, specific examples of the amphoteric surfactant include alkylbetaine and alkylamine oxide.

Further, specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, glycerin fatty acid ester, and polyoxyethylene fatty acid ester. Polyoxyethylene alkylamine, alkyl alkanolamine.

These surfactants may be used alone or in combination of two. Used above.

6. About other additives

In order to improve the performance of the polishing composition of the present embodiment, a well-known additive contained in a general polishing composition may be further added as needed. For example, various additives such as a pH adjuster, an oxidizing agent, an anticorrosive agent, a chelating agent, a dispersing aid, a preservative, and an antifungal agent may be added.

6-1 About pH adjuster

In the polishing composition of the present embodiment, a pH adjuster may be added as needed in order to adjust the pH to a desired value. The pH adjuster to be used may be either an acid or a base, and may be either an inorganic compound or an organic compound. As the pH adjuster, for example, nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid, citric acid or the like can be used.

The pH of the polishing composition of the present embodiment is not particularly limited, but may be 7 or more and 11 or less.

6-2 About oxidants

In the polishing composition of the present embodiment, in order to oxidize the surface of the object to be polished, an oxidizing agent may be added as needed. The oxidizing agent has an effect of oxidizing the surface of the object to be polished, and when an oxidizing agent is added to the polishing composition, the polishing rate is improved by the polishing composition.

The oxidizing agent which can be used is, for example, a peroxide Specific examples of the peroxide include hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, perchloric acid, and persulfate (for example, sodium persulfate, potassium persulfate, and ammonium persulfate).

6-3 About corrosion inhibitors

In the polishing composition of the present embodiment, in order to suppress corrosion of the surface of the object to be polished, an anticorrosive agent may be added as needed. Specific examples of the anticorrosive agent include amines, pyridines, tetraphenylphosphonium salts, benzotriazoles, triazoles, tetrazoles, and benzoic acid.

6-4 About chelating agents

In the polishing composition of the present embodiment, the metal impurity component in the polishing system is captured to form a complex compound, whereby metal contamination of the object to be polished can be suppressed, and a chelating agent can be added as needed. Specific examples of the chelating agent include a carboxylic acid, an amine, an organic phosphonic acid, an amino acid, and the like.

6-5 About Dispersing Aids

In the polishing composition of the present embodiment, in order to facilitate the redispersion of the suspected abrasive grains, a dispersing aid may be added as needed. Specific examples of the dispersing aid include condensed phosphates such as pyrophosphate or hexametaphosphate.

6-6 About preservatives, anti-mold agents

In the polishing composition of the present embodiment, a preservative or a mold inhibitor may be added as needed. Examples of the preservative and the antifungal agent include isothiazoline such as 2-methyl-4-isothiazolin-3-one or 5-chloro-2-methyl-4-isothiazolin-3-one. It is a preservative, or a paraben, or phenoxyethanol.

7. Close liquid medium

The polishing composition of the present embodiment may contain a liquid medium such as water or an organic solvent. The liquid medium has a dispersion medium for dispersing or dissolving each component (abrasive grains, a quaternary ammonium salt having a benzene ring in the structure, a water-soluble polymer, a surfactant, an additive, etc.) in the polishing composition or The function of the solvent.

The liquid medium may, for example, be used alone or in combination of two or more kinds, and preferably contains water. However, from the viewpoint of suppressing the action of the respective components, it is preferred to use water which is as free from impurities as possible. Specifically, it is preferably pure water or ultrapure water or distilled water obtained by removing foreign matter by an ion exchange resin and removing foreign matter through a filter.

8. Method for producing polishing composition

The method for producing the polishing composition of the present embodiment is not particularly limited. For example, it can be stirred and mixed with a liquid medium such as water, and the abrasive grains, the quaternary ammonium salt, and the water-soluble polymer and the surfactant can be mixed. At least one, manufactured with various additives as desired. The temperature at the time of mixing is not particularly limited, but is preferably 10 ° C or more and 40 ° C or less in order to increase the dissolution rate. Degree, can also be heated. Further, the mixing time is also not particularly limited.

9. Method for grinding the object to be polished

The method or the condition for polishing the object to be polished by using the polishing composition of the present embodiment is not particularly limited, and a general polishing method and a method suitable for polishing the object to be polished within a range of conditions can be suitably selected. Grinding is performed by selecting conditions. For example, a polishing device (single-sided) can be used by allowing a polishing composition to exist between a polishing object (for example, a germanium wafer on which a film of a polysilicon film is deposited on a tantalum nitride film) and a polishing pad. The polishing apparatus, the double-side polishing apparatus, and the like are polished under general polishing conditions to polish the object to be polished.

For example, a germanium wafer on which a film of a polycrystalline germanium film is deposited on a tantalum nitride film is used as an object to be polished, and when a single-side polishing device is used for polishing, a germanium wafer is held by a holder called a carrier. The platen to which the polishing pad is attached is pressed to one side of the silicon wafer, and the pressure plate is rotated while the polishing composition is supplied to polish one side of the silicon wafer.

Further, when the tantalum wafer is polished using a double-side polishing apparatus, a holder called a carrier is used to hold the wafer, and the pressure plate to which the polishing pad is attached is pressed from the both sides of the wafer to the twin On both sides of the circle, both sides of the crucible wafer are polished by rotating the pressure plates on both sides while supplying the polishing composition.

The type of the polishing pad is not particularly limited, and may be a foam, or a non-foamed body such as a cloth or a non-woven fabric, and a general nonwoven fabric, a foamed polyurethane, a porous fluororesin or the like may be used. Further, in the polishing pad, it is also possible to apply a groove which is formed into a groove which is accumulated as a polishing composition. Make For the material of the polishing pad, polyurethane, acrylic, polyester, acrylate copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly 4-methylpentene, cellulose, cellulose ester can be used. , polyamide (nylon, aromatic polyamide, etc.), polyimine, polyamidamine, polyoxyalkylene copolymer, oxirane compound, phenol resin, polystyrene, polycarbonate , resin such as epoxy resin.

Further, the polishing composition of the present embodiment is collected after being polished for polishing, and can be reused for polishing the object to be polished. An example of a method of reusing the polishing composition is a method in which the polishing composition discharged from the polishing apparatus is collected in a tank and recirculated to the polishing apparatus to be used for polishing. When the polishing composition is recycled, the amount of the polishing composition discharged as the waste liquid can be reduced, and the environmental load can be reduced. Moreover, since the amount of the polishing composition to be used can be reduced, the manufacturing cost required for polishing the object to be polished can be suppressed.

When the polishing composition of the present embodiment is used, part or all of the abrasive grains, the quaternary ammonium salt, the water-soluble polymer, the surfactant, and the additive which are consumed and lost by polishing can be used as a composition adjuster. After adding it, use it again. As the composition adjusting agent, those which are mixed at any mixing ratio can be used using abrasive grains, quaternary ammonium salts, water-soluble polymers, surfactants, additives, and the like. By additionally adding a composition adjusting agent, it is possible to adjust to a composition suitable for the polishing composition and to perform appropriate polishing. The concentration of the abrasive grains, the quaternary ammonium salt, the water-soluble polymer, the surfactant, and the additive contained in the composition adjusting agent is not particularly limited, and is not particularly limited. Adjust according to the size of the tank or the grinding conditions.

In addition, the polishing composition of the present embodiment may be a one-liquid type, or a two-liquid type such as a two-liquid type in which part or all of the components of the polishing composition are mixed at an arbitrary ratio. Further, in the polishing composition of the present embodiment, the stock solution may be directly used for polishing, or the stock solution may be diluted with a liquid medium such as water, and the obtained dilution of the polishing composition may be used for polishing.

[Examples]

The present invention will be more specifically described below by showing examples and comparative examples.

(Example 1)

The abrasive composition, the quaternary ammonium salt, the water-soluble polymer, and water were mixed to prepare a polishing composition (see Table 1). The abrasive grains were colloidal vermiculite having an average primary particle diameter of 35 nm, and the concentration of the abrasive grains in the polishing composition was 2.0% by mass. The quaternary ammonium salt is benzyltrimethylammonium hydroxide (hereinafter referred to as "BTMAH"), and the concentration of BTMAH in the polishing composition is 0.05% by mass. The water-soluble polymer was a poly-N-vinylpyrrolidone having a weight average molecular weight (Mw) of 45,000 (hereinafter referred to as "PVP"), and the concentration of PVP in the polishing composition was 0.02% by mass. Further, the pH of the polishing composition was 10.0.

(Examples 2 to 9)

A polishing composition was produced in the same manner as in Example 1 except that the concentration of the abrasive grains, the concentrations of BTMAH and PVP, and the weight average molecular weight (Mw) of the PVP in the polishing composition were as shown in Table 1. The pH of these polishing compositions is shown in Table 1.

(Embodiment 10)

In addition to the PVP which is a water-soluble polymer, a polyvinyl methyl ketone having a weight average molecular weight of 500,000 (hereinafter referred to as "PVMK") is used, and the concentration of PVMK in the polishing composition is 0.05% by mass or less. In the same manner as in Example 2, a polishing composition was produced in the same manner. The pH of the polishing composition was 10.0.

(Example 11)

In place of PVP as a water-soluble polymer, a methyl vinyl ether/maleic anhydride alternating copolymer having a weight average molecular weight of 216,000 (hereinafter referred to as "PMVEMA") was used, and the concentration of PMVEMA in the polishing composition was 0.05 mass. A polishing composition was produced in the same manner as in Example 2 except for the point of %. The pH of the polishing composition was 10.0.

(Embodiment 12)

This embodiment is an example in which a surfactant is used in place of the water-soluble polymer. In addition to replacing water-soluble polymers, ammonium lauryl sulfate using a surfactant (The following is a description of "ALS"), and a polishing composition was produced in the same manner as in Example 2 except that the concentration of ALS in the polishing composition was 0.10% by mass. The pH of the polishing composition was 10.0.

(Comparative Example 1)

In the same manner as in Example 2, polishing was carried out in the same manner as in Example 2, except that BTMAH was used as the quaternary ammonium salt, and trimethylammonium hydroxide (hereinafter referred to as "TMAH") was used, and the concentration of TMAH in the polishing composition was changed to 0.07% by mass. Use the composition. The pH of the polishing composition was 10.4.

(Comparative Example 2)

The same procedure as in Example 4 was carried out except that BTMAH was used as the quaternary ammonium salt, and triethylammonium hydroxide (hereinafter referred to as "TEAH") was used, and the concentration of TEAH in the polishing composition was changed to 0.08% by mass. A composition for polishing. The pH of the polishing composition was 10.2.

(Comparative Example 3)

The same procedure as in Example 4 was carried out except that BTMAH was used as the quaternary ammonium salt, and tributylammonium hydroxide (hereinafter referred to as "TBAH") was used, and the concentration of TBAH in the polishing composition was changed to 0.12% by mass. A composition for polishing. The pH of the polishing composition was 10.1.

(Comparative Example 4)

In addition to replacing the quaternary ammonium salt, ammonia is used as the base to make the polishing composition A polishing composition was produced in the same manner as in Example 2 except that the concentration of ammonia in the mixture was 0.07 mass%. The pH of the polishing composition was 10.0.

(Comparative Example 5)

A polishing composition was produced in the same manner as in Example 4 except that instead of the quaternary ammonium salt, ammonia was used as the base and the concentration of ammonia in the polishing composition was changed to 0.07 mass%. The pH of the polishing composition was 10.0.

(Comparative Example 6)

A polishing composition was produced in the same manner as in Example 6 except that instead of the quaternary ammonium salt, ammonia was used as the base and the concentration of ammonia in the polishing composition was changed to 0.07 mass%. The pH of the polishing composition was 10.0.

(Comparative Example 7)

A polishing composition was produced in the same manner as in Example 10 except that instead of the quaternary ammonium salt, ammonia was used as the base and the concentration of ammonia in the polishing composition was changed to 0.07 mass%. The pH of the polishing composition was 10.0.

(Comparative Example 8)

A polishing composition was produced in the same manner as in Example 11 except that instead of the quaternary ammonium salt, ammonia was used as the base and the concentration of ammonia in the polishing composition was changed to 0.07 mass%. The pH of the polishing composition was 10.0.

(Comparative Example 9)

In place of the quaternary ammonium salt, ammonia is used as the base, and the concentration of ammonia in the polishing composition is 0.07 mass%. Instead of PVP as the water-soluble polymer, polyvinyl alcohol having a weight average molecular weight of 40000 is used (described below). In the same manner as in Example 2, a polishing composition was produced in the same manner as in Example 2 except that the concentration of PVA in the polishing composition was changed to 0.10% by mass. The pH of the polishing composition was 10.0.

(Comparative Example 10)

In place of the quaternary ammonium salt, ammonia is used as the base to make the concentration of ammonia in the polishing composition 0.07 mass%, and instead of the PVP as the water-soluble polymer, hydroxyethyl cellulose having a weight average molecular weight of 250,000 is used. (Hereinafter referred to as "HEC"), a polishing composition was produced in the same manner as in Example 2 except that the concentration of HEC in the polishing composition was 0.04% by mass. The pH of the polishing composition was 10.0.

(Comparative Example 11)

In place of the quaternary ammonium salt, ammonia is used as the base to make the concentration of ammonia in the polishing composition 0.07 mass%, and instead of the PVP as the water-soluble polymer, polyoxyethylene having a weight average molecular weight of 1,100 is used. In the same manner as in Example 2, a polishing composition was produced in the same manner as in Example 2 except that the polyoxypropylene (17) diol (hereinafter referred to as "POEPOP") was used, and the concentration of POEPOP in the polishing composition was changed to 0.10% by mass. The pH of the polishing composition was 10.0.

Also, the "(3)" meaning of polyoxyethylene (3) polyoxypropylene (17) diol is Refers to the average repeat number of oxyethylene units is 3. Similarly, "(17)" means that the average number of repeats of the oxypropylene unit is 17.

(Comparative Example 12)

A polishing composition was produced in the same manner as in Example 12 except that instead of the quaternary ammonium salt, ammonia was used as the base and the concentration of ammonia in the polishing composition was changed to 0.07 mass%. The pH of the polishing composition was 10.0.

Next, the polishing target is polished using the polishing composition. First, a tantalum wafer (manufactured by SVM Co., Ltd.) having a polycrystalline tantalum film on its surface and a tantalum wafer (manufactured by SVM Co., Ltd.) having a tantalum nitride film on its surface are used as polishing targets, and the same polishing method and polishing conditions are used. Each of them was polished to calculate the polishing rates of polycrystalline germanium and tantalum nitride. Then, the ratio of the polishing rate of the polysilicon to the polishing rate of the tantalum nitride (the polishing rate ratio) was calculated from the calculated polishing rate of the polysilicon and the polishing rate of the tantalum nitride.

Table 1 shows the values of the respective polishing rates and polishing rates. The polishing rate is calculated by dividing the difference in film thickness between the polysilicon film or the tantalum nitride film of the tantalum wafer before and after the polishing by the polishing time. Therefore, the unit of the polishing speed is nm/min. The film thickness of the polycrystalline tantalum film or the tantalum nitride film was measured using a film thickness measuring device ASET-F5x (trade name) manufactured by KLA-Tencor Co., Ltd.

The grinding conditions are as follows.

Grinding device: CMP device F-REX300E (trade name) manufactured by Ebara Seisakusho Co., Ltd.

Polishing pad: polishing pad IC1010 (trade name) made by DOW Electronic Materials Co., Ltd.

Grinding load: 10.3kPa

Platen rotation speed: 60rpm

Carrier rotation speed: 65rpm

Grinding time: 1 minute

Feeding speed of the polishing composition: 300 mL/min (for overflow use)

Next, the germanium wafer (see FIG. 1) on which the wiring was formed was used as the object to be polished, and the polishing compositions of Examples 1 to 12 and Comparative Examples 1 to 12 were used for polishing. First, the configuration of the germanium wafer for polishing an object will be described with reference to FIG. 1 . This tantalum wafer is a 300 mm-diameter wafer manufactured by Advanced Materials Technology Co., Ltd., and a tantalum oxide film 2, a tantalum nitride film 3, and a polysilicon film 4 are formed on the tantalum substrate 1.

In detail, the yttrium oxide film 2 (having a film thickness of 12.5 nm) by thermal oxidation is formed on the ruthenium substrate 1, and is formed on the ruthenium oxide film 2 by a reduced pressure chemical vapor deposition method. Tantalum nitride film 3 (film thickness 70.0 nm). Then, one portion of the hafnium oxide film 2 and the tantalum nitride film 3 is removed to form a plurality of groove-like grooves (minimum width 0.18 μm). Further, a polycrystalline germanium film 4 (having a film thickness of 152.5 nm) was deposited on the tantalum nitride film 3, and polycrystalline germanium was also buried in the trench.

A step (step) 4a is formed in a portion above the groove of the surface of the tantalum wafer (the surface of the polysilicon film 4). The step height of this step 4a is 70 nm. Then, using the polishing compositions of Examples 1 to 12 and Comparative Examples 1 to 12, the surface of the silicon wafer was polished and measured after polishing. The step height of the residual step 4a.

The grinding conditions are as follows.

Grinding device: EJ-380IN (trade name) manufactured by ENGIS Co., Ltd., Japan

Polishing pad: polishing pad IC1010 (trade name) made by DOW Electronic Materials Co., Ltd.

Grinding load: 6.9kPa

Platen rotation speed: 70rpm

Grinding time: 1 minute

Feeding speed of the polishing composition: 100 mL/min (for overflow use)

Further, in the measurement of the step height, a high-resolution surface topographic drawing system HRP340 (trade name) manufactured by KLA-Tencor Co., Ltd. was used. The results are shown in Table 1. In Table 1, when the step height of the step 4a remaining after polishing is less than 8 nm, it is represented by "A", and when it is 8 nm or more and less than 12 nm, it is represented by "B", and when it exceeds 12 nm, it is represented by "C".

As can be seen from Table 1, in the polishing using the polishing compositions of Examples 1 to 12, the polishing rate ratio was large, the polishing rate of the polycrystalline silicon was large, and the polishing rate of the tantalum nitride was small. Further, the step height is A or B, and the step difference 4a remaining after the polishing is small.

In the polishing using the polishing compositions of Comparative Examples 1 to 12, the polishing rate of the polycrystalline silicon was large or the polishing rate of the tantalum nitride was small, but the polishing rate ratio was as small as 250. Further, as for the step height, there are also A or B, but there are also C (the step difference 4a remaining after polishing) is large.

1‧‧‧矽 substrate

2‧‧‧Oxide film

3‧‧‧ nitride film

4‧‧‧Polysilicon film

4a‧‧ ‧ step

Claims (3)

A polishing composition for polishing a polishing object having at least one of polycrystalline germanium and amorphous germanium and a polishing target of tantalum nitride, comprising abrasive grains and quaternary ammonium having a benzene ring in the structure At least one of a salt, a water soluble polymer, and a surfactant. The polishing composition according to claim 1, wherein the water-soluble polymer is a nitrogen-containing water-soluble polymer. The polishing composition according to claim 1 or 2, wherein the ammonium ion of the quaternary ammonium salt is represented by the following Chemical Formula 1, wherein x in the following Chemical Formula 1 is an integer of 1 or more and 15 or less, and each of y, z and w Independently an integer of 0 or more and 4 or less;