WO2005034226A1

WO2005034226A1 - Metal polishing composition

Info

Publication number: WO2005034226A1
Application number: PCT/JP2004/014235
Authority: WO
Inventors: Shinji Funakoshi; Koshi Okita
Original assignee: Asahi Kasei Chemicals Corporation
Priority date: 2003-10-01
Filing date: 2004-09-29
Publication date: 2005-04-14
Also published as: TW200530377A; JP2007012638A

Abstract

A metal polishing composition is disclosed which contains a polyoxo acid, an anionic surfactant and water.

Description

Specification

Metal polishing composition

Technical field

The present invention relates to a polishing composition used for polishing a metal film formed on a semiconductor substrate, a method for polishing a metal film on a semiconductor substrate using the polishing composition, and a method for manufacturing a semiconductor substrate. About the method.

Background art

[0002] With the rapid progress of LSI technology, integrated circuits are becoming more and more miniaturized and multilayered. Multi-layer wiring in integrated circuits is a cause of extremely large irregularities on the semiconductor surface, which, coupled with the miniaturization of integrated circuits, leads to disconnection, reduction in electric capacity, generation of electrification, and reduction in yield. And reliability problems.

[0003] For this reason, various processing techniques for flattening metal wirings and interlayer insulating films in a multilayer wiring board have been developed, one of which is CMP (Chemical Mechanical Polishing). Polishing) technology. CMP technology is required for semiconductor manufacturing such as planarization of interlayer insulating film, formation of embedded wiring, and plug formation.

[0004] CMP is performed by rotating each of the carrier and the polishing pad while pressing a flat wafer mounted on the carrier, which is also usually a semiconductor material, with a constant pressure against a wet polishing pad. At this time, the projections of the wiring and the insulating film are polished and flattened by the polishing composition introduced between the wafer and the polishing pad.

Conventionally, various polishing compositions and polishing methods have been proposed for polishing a metal film formed on a semiconductor substrate. As shown in Toyo Toshi et al., “Semiconductor flattening CMP technology” (July 1998, published by the Industrial Research Institute), page 235 (Non-Patent Document 1), metal CMP involves oxidation in the polishing composition. While the surface of the metal is oxidized by the agent, the pH is acidified or the like, and the metal is slightly corroded (etched), and the polishing is performed with a polishing pad and a cannonball. For example, as a polishing composition for a metal film such as an aluminum film formed on a semiconductor substrate, a polishing composition obtained by dispersing aluminum oxide in a nitric acid aqueous solution having a pH of 3 or less (patented) Literature 1: US Patent No. 4,702,792), a polishing composition comprising aluminum oxide or silicon oxide mixed with an acidic aqueous solution of sulfuric acid, nitric acid, acetic acid or the like (Patent Document 2: US Patent No. 4,944,836) Book). Further, aluminum oxide or silicon oxide such as a polishing composition (Patent Document 3: US Pat. No. 5,209,816) prepared by dispersing aluminum oxide in an aqueous solution of hydrogen peroxide and phosphoric acid. A polishing composition composed of a cannonball and an oxidizing agent such as hydrogen peroxide is generally used.

[0006] When oxidized aluminum is used for flattening a metal film on a semiconductor substrate while pressing, a type A has a high polishing rate. On the other hand, although the polishing rate is high, micro scratches are formed on the surface of the metal film or the insulating film. And orange peel and other defects. On the other hand, when abrasive grains such as γ-type, amorphous alumina or silicon oxide are used, the ability to suppress the occurrence of defects such as micro scratches and orange peel on the surface of the metal film or the insulating film. However, there was a problem that a sufficient polishing rate could not be obtained when polishing the substrate. As described above, the polishing composition in which the abrasive grains made of metal oxide such as aluminum oxide and silicon oxide are dispersed in the aqueous solution has a problem of surface scratches due to poor dispersibility of the abrasive grains themselves. was there. In addition, when hydrogen peroxide as a liquid oxidizing agent is used as described above, or when a metal etchant such as ammonium persulfate is used (Patent Document 4: Japanese Patent Application Laid-Open No. 6-313164), Excessive wet etching leads to dicing (a phenomenon in which the center of the metal film 4 is polished excessively from the periphery as shown in Fig. 1 (D)) and defects such as pits and voids. There was a problem.

[0007] To improve this, a method has been proposed in which a chemical reagent (corrosion inhibitor, chelating agent, etc.) for forming a protective film on the metal film surface is added to the polishing composition (Patent Document 5). : JP-A-8-83780, Patent document 6: JP-A-11-195628). However, when such a chelating agent is used, etching is surely suppressed and occurrence of dicing or the like can be prevented. However, since a protective film is formed on a portion to be polished, the polishing rate is extremely reduced. Problem arises. To prevent this, attempts have been made to optimize the amounts of the etching agent and the chelating agent.However, it is difficult to find conditions that satisfy the performance of both. There is a problem that certain results cannot be obtained. In addition, in order to obtain a high polishing rate and a polishing rate of 200 gZcm ² or more, The protective film may be removed by polishing pressure (Patent Document 7: Japanese Patent Application Laid-Open No. 2000-252242). However, when this method is used, when a porous low dielectric constant insulating film, which is expected to become the mainstream in the future, is used for manufacturing a semiconductor substrate, there is a problem in the strength of the insulating film. There is a problem that the destruction of the insulating film occurs when strong stress is applied.

[0008] By the way, polyoxoacids, especially heteropolyacids, are described in "Chemistry of Polyacids", edited by The Chemical Society of Japan (August 1993, published by the Society Press Center) (Non-Patent Document 2). It has a strong acidity and an oxidizing effect, and its use for passivation and etching of metals is described in JP-A-9-505111 (Patent Document 8) and the like. Examples of actually applying heteropolyacid as an etchant for semiconductor surfaces (Non-Patent Document 3: Applied Surface Science vol. 135, No. 1, 4, pp. 65-70 (Oct. 1998, 1998)) Attempts have also been made to use salt as a polishing etchant (Patent Document 9: JP-A-2000-119639). In particular, the latter includes a case where only polyoxoacid or a salt thereof is used as an etching agent for polishing (first polishing composition) and a case where abrasive particles known as an abrasive are further added thereto (second polishing composition). The two usages are described. In the case of the first polishing composition, when the heteropoly acid is used alone as an etching agent for polishing a metal film, the heteropoly acid is soluble in water and thus acts as a liquid oxidizing agent. We cannot satisfy both performances. That is, when the concentration of the heteropolyacid is increased to increase the polishing rate, the etching also proceeds at the same time, causing the occurrence of dicing. On the other hand, when a basic substance such as ammonia is allowed to act on the above-mentioned heteropolyacid to be used as a heteropolyacid salt, the etching is suppressed and the polishing rate is reduced. Therefore, in order to increase the polishing rate, it has been proposed to include an abrasive in this type of first polishing composition to form a second polishing composition, but in this case also, the first polishing composition described above is used. It is difficult to suppress the occurrence of dishing due to the progress of etching in the same manner as described above. Therefore, this method does not meet the purpose of obtaining a high polishing rate at a low polishing pressure while suppressing the occurrence of dicing.

[0009] There has been proposed a polishing method that utilizes the high etching property of polyoxoacid to obtain a high polishing rate and at the same time suppresses dicing (for example, Patent Document 10: JP-A-2003-173). 990, Patent Document 11: Japanese Patent Application Laid-Open No. 2004-189894). Patent Document 10 discloses a polishing slurry containing a polyoxoacid, a nonionic surfactant, and water as main components. The fine particles of the composite are formed by the interaction between the polyoxoacid and the nonionic surfactant, and the polyoxoacid is incorporated into the fine particles of the composite, thereby maintaining a low etching property and suppressing the occurrence of dating. It is presumed that a high polishing rate can be achieved even at a low load due to the chemical polishing effect of the method. However, the composite fine particles are unstable, and there is a disadvantage that the polishing performance changes with time when the polishing composition having the above composition is stored. The present inventors also disclosed in Patent Document 11 a polishing composition containing polyoxoacid, a nonionic surfactant, an aionic surfactant and water as main components for improving the storage stability. However, further improvements in performance have been required, for example, such as 50 gZcm ² or less t, low polishing speed, polishing speed at polishing pressure, and storage stability of the polishing composition.

Patent Document 1: U.S. Pat.No. 4,702,792

Patent Document 2: U.S. Pat.No. 4,944,836

Patent Document 3: U.S. Pat.No. 5,209,816

Patent Document 4: JP-A-6-313164

Patent Document 5: JP-A-8-83780

Patent Document 6: JP-A-11-195628

Patent Document 7: JP-A-2000-252242

Patent Document 8: JP-A-9-505111

Patent Document 9: JP-A-2000-119639

Patent Document 10: Japanese Patent Application Laid-Open No. 2003-173990

Patent Document 11: JP-A-2004-189894

Non-patent Document 1: Toshio Dohi et al., "Semiconductor Flattening CMP Technology", First Edition, Published by the Industrial Research Council, July 15, 1998, p.235

Non-patent document 2: Chemical Society of Japan, "Chemistry of Polyacids", First Edition, Academic Press, August 25, 1993, 86-87, 112-123

Non-Patent Document 3: A. Rothschild, C. Debiemme-Chouvy, A. Etcheberrv, `` St udy of the interaction at rest potential between silicotungstic het eropolyanion solution and GaAs surface '' Applied Surface Science ^ 1 Oct. 8, 998, vol. 135, No. 1, 4, pp65-70

Disclosure of the invention

Problems to be solved by the invention

[0011] The present invention provides a metal polishing composition which can polish a metal film on a semiconductor substrate at high speed even under a low polishing pressure, and can suppress generation of defects on a surface to be polished such as dicing and scratching. An object of the present invention is to provide a method for polishing a metal film on a semiconductor substrate, which comprises using the same, and a method for manufacturing a semiconductor substrate.

Means for solving the problem

[0012] The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, a metal polishing composition containing a polyoxoacid, a surfactant, and water has been conventionally difficult to etch. The present inventors have found that it is possible to achieve both a suppression of dicing and a high polishing rate at a low polishing pressure, and it is effective in polishing a metal film on a substrate. Thus, the present invention has been accomplished. That is, the present invention is as follows.

1) A metal polishing composition comprising a polyoxo acid, an aionic surfactant and water.

2) The metal polishing composition according to 1) above, wherein the polyoxo acid is a heteropoly acid.

3) The metal polishing composition according to 1) or 2) above, wherein the ionic surfactant is an acid type.

4) The metal polishing composition according to 1) to 3) above, comprising a water-soluble polymer compound and Z or a polyhydric alcohol compound.

5) The metal polishing composition according to 1) to 4) above, which contains an organic compound having a nitrogen atom and a carboxyl group in the molecule.

6) The metal polishing composition according to 1) to 5), wherein the metal polishing composition is substantially free of cannonballs.

7) The metal polishing composition according to any one of 1) to 6) above, which does not substantially contain a nonionic surfactant.

8) A method for polishing a metal film on a semiconductor substrate, comprising using the metal polishing composition according to any one of 1) to 7) above. 9) A method for producing a semiconductor substrate, comprising a polishing step using the metal polishing composition according to any one of 1) to 7) above.

The invention's effect

[0013] According to the metal polishing composition of the present invention, it is possible to polish a metal film such as a copper film at a high speed even under a low polishing pressure while suppressing etching and dishing, which has been difficult in the prior art. It becomes. The present invention has found a material having extremely useful performance in polishing a metal film on a semiconductor substrate, and its industrial value is extremely large.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] The present invention is specifically described below.

In the present invention, low polishing pressure means a pressure of 100 gZcm ² or less, and high-speed polishing means a polishing rate of 5 OO nm / min or more.

The metal polishing composition of the present invention comprises a polyoxoacid, an aionic surfactant and water. As described below, the polishing composition of the present invention can contain components such as commonly used abrasive particles and additives within a range that does not impair the effects of the present invention or depending on the purpose. It is characterized in that the object of the present invention can be achieved with only the above three components. That is, the polishing composition of the present invention has a feature of exhibiting excellent polishing performance even without substantially containing abrasive grains. Here, “substantially free of abrasive grains” refers to a state in which the proportion of the mass of the cannon particles in the total mass of the polishing composition is less than 1%.

[0015] The polyoxoacid used in the present invention is a condensed oxyacid containing constituent elements such as Mo, V, W, Ti, Nb, and Ta. Isopolyacid and heteropolyacid correspond to this.

Isopolyacid is a condensed oxyacid in which the above-mentioned constituent element of polyoxoacid is a single element, and examples thereof include polymolybdic acid, polyvanadic acid, polytungstic acid, polytitanic acid, polyniobic acid, and polytantalic acid. Among them, in the case of the present invention for the purpose of metal polishing, polymolybdic acid, polyvanadic acid, and polytungstic acid are preferable from the viewpoint of the polishing rate of the obtained metal polishing composition.

[0016] The heteropoly acid is obtained by incorporating a hetero element into the isopoly acid as a central element, and its configuration also includes a condensed coordination element, a central element, and oxygen power. here In the above, the condensed coordination element means the above-mentioned constituent element of the polyoxo acid, and a group consisting of Mo, W and V is preferably at least one selected from the group consisting of Mo, W and V, and other elements such as Nb and Ta. May be included. The central element of the heteropolyacid is selected from the group consisting of P, Si, As, Ge, Ti, Ce, Mn, Ni, Te, I, Co, Cr, Fe, Ga, B, V, Pt, Be and Zn. The atomic ratio between the condensed coordination element and the central element (condensed coordination element Z central element) is given by 2.5-12.

[0017] Specific examples of the above-mentioned heteropolyacids include phosphomolybdic acid, chemolybdic acid, phosphovanadomolybdic acid, cayvanadomolybdic acid, phosphorus tandust molybdic acid, keitandostamolybdic acid, lyvanadang tungstomolybdic acid, Cavanado tungstomolybdate, phosphovanadotungstic acid, cavanadotungstic acid, phosphomolybdniobate, boromolybdate, botandust molybdate, borovanadomolybdate, borovanadotanstenic acid, cobalt molybdate, cobalt vanad Forces such as tungstic acid, phosphotungstic acid, caytungstic acid, phosphovanadic acid, cavanadic acid and the like are not limited to these.

Of the polyoxo acids, acid strength sufficient to etch metals for polishing purposes, and heteropoly acid is also preferred in terms of acidity, preferably phosphomolybdic acid, chemolybdic acid, and furthermore, Examples thereof include phosphorus vanadomolybdic acid and cavanadomolybdic acid into which vanadium has been introduced.

[0018] In order to control the polishing performance by adjusting the acidity of the obtained polishing composition, a basic substance is added to these polyoxo acids, and a part or all of the polyoxo acids is used as a polyoxo acid salt. Is also possible. Examples of the polyoxo acid salt include salts of the above-mentioned polyoxo acids with metals, ammonium and organic amines.

However, from the viewpoint of the polishing rate of the metal polishing composition of the present invention, the above-mentioned polyoxoacid is preferably an acid-type polyoxoacid, which forms a salt.

The content of polyoxoacid in the polishing composition of the present invention is preferably in the range of 0.1 to 30% by mass, and more preferably in the range of 0.5 to 15% by mass. From the viewpoint of easy polishing control, 0.1% by mass or more is preferred, and 30% by mass or less is preferred. [0019] By adding an aionic surfactant to the composition of the present invention, it is possible to suppress the etching of the metal to be polished by the polyoxoacid, and to flatten the metal film to be polished and dicing. Thus, a polishing composition having a polishing performance such as suppression of the polishing resistance can be obtained.

Examples of the aionic surfactant used in the present invention include a fatty acid or a salt thereof, an alkylsulfonic acid or a salt thereof, an alkylbenzenesulfonic acid or a salt thereof, an alkyl sulfosuccinic acid or a salt thereof, a polyoxyethylene alkyl sulfate or a salt thereof. Polyoxyethylene alkylaryl sulfuric acid or a salt thereof, p-styrenesulfonic acid or a salt thereof, alkyl naphthalenesulfonic acid or a salt thereof, naphthalenesulfonic acid or a salt thereof, naphthenic acid or a salt thereof, an alkyl ether carboxylic acid or a salt thereof, α-olefin sulfonic acid or its salt, dimethylmethyltaurine, alkyl ether sulfate or its salt, polyoxyethylene alkyl alkyl ether sulfate or its salt, alkyl ether phosphate or its salt, alkyl phosphate or its salt Salt, acylated pepti , Formalin polycondensate, condensate of higher fatty acids and amino acids, mono- grease sulfates, secondary higher alcohol Rue Toki Thistle phosphate, and the like dialkyl sulfosuccinate salts. In the present invention, carbon-carbon double bonds (excluding benzene ring) are not included at all! / Saturated type is not easily deteriorated by oxidizing and does not deteriorate with time. Alkyl sulfonic acid or a salt thereof, alkyl benzene sulfonic acid or a salt thereof, alkyl sulfosuccinic acid or a salt thereof, polyoxyethylene alkyl sulfuric acid or a salt thereof, and polyoxyethylene alkylaryl sulfuric acid or a salt thereof are preferred. More preferably, alkyl sulfonic acid, alkyl benzene sulfonic acid, alkyl sulfosuccinic acid, polyoxyethylene alkyl sulfuric acid, and polyoxyethylene alkyl aryl sulfuric acid are used.

From the viewpoints of the polishing rate and storage stability of the metal polishing composition of the present invention, the above-mentioned aionic surfactant is preferably an acid-type surfactant rather than a salt-forming surfactant.

In the present invention, the above-mentioned anionic surfactants can be used alone or in combination of two or more.

The content of the a-ionic surfactant in the polishing composition of the present invention varies depending on the type and amount of the polyoxoacid used, and is preferably 0.0001-30 relative to the total amount of the polyoxoacid. %, More preferably 0.1-20% by mass. De The content of the a-ionic surfactant is preferably 0.001% by mass or more from the viewpoint of suppressing the isting, and 30% by mass or less from the viewpoint of the polishing rate.

The polishing composition of the present invention usually uses water as a medium. The dissolution of the polyoxoacid and the ionic surfactant is carried out by stirring using a commonly used stirring blade. It is also preferable to sufficiently stir using a homogenizer, an ultrasonic wave, a wet medium mill or the like.

Although the details of the polishing mechanism of the polishing composition of the present invention are not clear, when a polishing composition in which only polyoxoacid is dissolved is used, an extremely high polishing rate is obtained due to its high etching property with respect to a metal to be polished. Can be obtained, but the surface of the metal film does not flatten, and intense dating occurs.However, a polyoxoic acid is mixed with an aionic surfactant in an appropriate ratio, and is mixed with the polishing composition of the present invention. In this case, the etching property of the polyoxoacid is suppressed, polishing proceeds only at the portion where the convex portion of the metal film to be polished contacts the polishing pad, a flat metal film surface is obtained, and occurrence of dicing is suppressed. I found out. From this fact, the ionic surfactant suppresses the etching property of polyoxoacid by some action, and further, the erosion due to the friction generated between the polishing pad and the convex portion of the metal film or the high shear generated in the liquid film, It is presumed that the effect of the surfactant to suppress the etching property of polyoxoacid is hindered, and that polishing of only the convex portions of the metal film proceeds.

[0022] Therefore, the polishing composition of the present invention is characterized in that it does not require abrasive grains conventionally added for the purpose of mechanical polishing. Problems such as scratching on the membrane surface and sedimentation of gunshots are eliminated. Further, it is known that the polishing rate is proportional to the polishing pressure in a conventional polishing composition which requires mechanical polishing with a cannonball. However, when the polishing composition of the present invention is used, the polishing rate is reduced. Polishing does not proceed below a certain polishing pressure threshold, which is not proportional to the pressure. When the polishing pressure exceeds the threshold, a sharply high polishing rate is obtained. The threshold value varies depending on the composition of the polishing composition of the present invention. The threshold value is low, and by selecting the composition, a high polishing rate can be obtained at a low polishing pressure, and the underlying substrate can be obtained by the polishing pressure during polishing. Problems such as damage to the head are eliminated.

The inclusion of an organic compound having both a nitrogen atom and a carboxyl group in the molecule in the metal polishing composition of the present invention is also preferable from the viewpoint of suppressing dating. nitrogen Organic compounds having both atoms and carboxyl groups in the molecule include cystine, dalysine, glutamic acid, aspartic acid, quinaldic acid, quinolinic acid, picolinic acid, nicotinic acid, histidine, benzotriazole carboxylic acid, glutamine, glutathione, and glycylglycine. , Alanine, γ-aminobutyric acid, ε-aminocaproic acid, arginine, titrulline, triptophan, threonine, cysteine, Ν-acetylscysteine, oxyproline, iso-isocyanine, leucine, lysine, methionine, phenylalanine, phenylglycine, Preferred examples include proline, serine, tyrosine, norin, and more preferred examples include quinaldic acid and histidine.

The addition amount of the organic compound having a nitrogen atom and a carboxyl group in the molecule is preferably 5000 ppm or less, preferably 100 ppm or less, more preferably 200 ppm or less in the polishing composition from the viewpoint of the polishing rate and the effect of suppressing the dishing. It is.

[0024] The polishing composition of the present invention does not require the use of a protective film-forming agent known in the art, since the etching property of the metal film causing the dicing is extremely low. The protective film-forming agent may be added, if necessary, within a practically acceptable range to further suppress the etching property. In particular, when the metal is copper or a copper alloy containing copper as a main component, benzotriazole, benzimidazole, tolyltriazole, quinoline, isoquinoline, indole, isoindole, quinazoline, cinnoline, glucose, quinoxaline, phthalazine, ataridine, dodecyl A preferred example is mercaptan.

The amount of the protective film forming agent to be added is 500 ppm or less, preferably 200 ppm or less, more preferably 100 ppm or less in the polishing composition, from the viewpoint of the polishing rate and the effect of suppressing the dishing.

[0025] The metal polishing composition of the present invention preferably contains a water-soluble polymer compound and Z or a polyhydric alcohol compound from the viewpoint of improving the polishing uniformity of the obtained polished surface.

Examples of the water-soluble polymer used in the present invention include ethers such as polyethylene glycol, polypropylene glycol and polyethylene glycol alkyl ether; vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone and polyacrolein; Polycarboxylic acids such as lylic acid, polymethacrylic acid, polyacrylamide, polyamic acid and polyacrylic acid ammonium salt and salts thereof; methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, cellulose acetate, nitric acid Preferred examples include polysaccharides such as cellulose, cellulose sulfate, and pectin, gelatin, starch, albumin, and the like, and more preferred are polyethylene glycol, hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose. .

[0026] In the present invention, the polyhydric alcohol compound is a low molecular compound other than the above-mentioned water-soluble polymer compound, and refers to a compound having a plurality of hydroxyl groups in one molecule, and includes ethylene glycol, Preferable examples include glycerin, propanediol, pentaerythritol, fructose, sucrose, jettyrene glycol, triethylene glycol, and the like, and more preferable examples include ethylenedalicol, glycerin, diethylene glycol, and triethylene glycol.

[0027] The content of the water-soluble polymer compound and Z or the polyhydric alcohol compound in the polishing composition of the present invention varies depending on the type thereof and the type and amount of the polyoxoacid used, but the total content of the polyoxoacid is different. On the other hand, it is preferably in the range of 0.01 to 30% by mass, and more preferably in the range of 0.1 to 20% by mass. That is, the viewpoint of the effect of the addition effect is also preferably 0.01% by mass or more.

[0028] As described above, the polishing composition of the present invention can perform the intended polishing without the use of munitions that are usually used for mechanical polishing. However, the polishing composition for the purpose of further increasing the polishing rate can be used. It is also possible to use grains. Examples of the cannonball used at this time include inorganic particles such as alumina, silica, cerium, zirconia, and magnesium oxide, and organic particles such as organic polymers, amorphous carbon, and carbon black. Is colloidal alumina and colloidal silica.

[0029] In the present invention, it is preferable that the metal polishing composition does not substantially contain a nonionic surfactant from the viewpoint of storage stability of the metal polishing composition. Although the cause is not clear, since the nonionic surfactant has a strong interaction with polyoxoacid, the above-mentioned composite particles are united and coarsened when the metal polishing composition is stored, and the storage stability is reduced. Estimated to lower The In the present invention, the phrase "contains substantially no nonionic surfactant" means that the solid content of the nonionic surfactant in the metal polishing composition is less than 0.01% by mass. Say.

[0030] Examples of such nonionic surfactants include, for example, "Introduction to New 'Surfactants Takehiko Fujimoto, published on November 1, 1985, Sanyo Chemical Industry Co., Ltd.," p. Examples include polyethylene glycol type and polyhydric alcohol type nonionic surfactants listed in the table. Examples of the polyethylene glycol type nonionic surfactant include those obtained by adding ethylene oxide to various hydrophobic groups to introduce a hydrophilic group, such as higher alcohol ethylene oxide adducts and alkylphenol ethylene oxides. Adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid esters carots with ethylene oxide, higher alkylamine ethylene oxide adducts, carohydrates with fatty acid amide ethylene oxide, fats and oils with ethylene oxide And carohydrates with polypropylene glycol ethylene oxide. On the other hand, polyhydric alcohol-type nonionic surfactants are obtained by bonding a hydrophobic fatty acid to a hydrophilic polyhydric alcohol via an ester or amide group, and include a glycerol fatty acid ester and a pentaerythritol fatty acid ester. And fatty acid esters of sorbitol and sorbitan, fatty acid esters of sucrose, fatty acid amides of alkanolamines and the like.

The polishing composition of the present invention is applied to polishing and flattening of a metal film formed on a semiconductor substrate. The metal films on the semiconductor substrate to be polished are known metal films for wiring, plugs, contact metal layers, and barrier metal layers, such as aluminum, copper, tungsten, titanium, tantalum, and aluminum alloys. , Copper alloy, titanium nitride, tantalum nitride, and the like. In particular, scratches and dishing with low surface hardness and cracks easily occur, and application to a metal film made of copper and a copper alloy is recommended.

As shown in FIG. 1 (C), for a semiconductor substrate obtained by embedding a metal film 4 for wiring, an extra metal film other than a groove or an opening as shown in FIG. The polishing composition is removed by polishing using the polishing composition, and the surface is flattened.

[0032] The method for manufacturing a semiconductor substrate of the present invention includes the steps of: forming a metal film on a semiconductor substrate such as a silicon substrate; The method is characterized by including a process of polishing using the polishing composition of the present invention. Hereinafter, an outline of an example of a method for manufacturing a semiconductor substrate will be described.

First, as shown in FIG. 1 (A), after an insulating film 2 is formed on a semiconductor substrate 1 such as a silicon substrate, a groove or connection for metal wiring is formed in the insulating film 2 by a photolithography method and an etching method. An opening for wiring is formed. Next, as shown in FIG. 1 (B), a barrier or metal having a force such as titanium nitride (TiN) or tantalum nitride (TaN) is formed in the groove or opening formed in the insulating film 2 by a method such as sputtering or CVD. Form layer 3. Next, as shown in FIG. 1C, the metal film 4 for wiring is buried so that the thickness is equal to or larger than the height of the groove or opening formed in the insulating film 2. Next, as shown in FIG. 1 (D), an excess metal film other than the groove or the opening is removed by a polishing method using the polishing composition of the present invention. Furthermore, a semiconductor substrate having a multilayer wiring structure can be obtained as an electronic component by forming an insulating film on the obtained flattened surface and repeating the above method a required number of times.

[0033] Polishing pressure using a metal polishing composition of the present invention is more preferably 0. 1- 140g / cm ² is preferred instrument 1 one 70 g / cm ² from the viewpoint of the viewpoint of polishing rate and Disshi ring suppression . The metal polishing composition of the present invention is supplied between a polishing surface of a polishing pad and a surface to be polished of an object to be polished, and the polishing surface is repeatedly polished to the surface to be polished, thereby polishing the surface to be polished. In the step of performing the polishing, it is preferable to remove the polishing waste liquid before the polishing waste liquid generated by the polishing processing reaches the polishing surface again while performing the polishing processing. More specifically, a rotating surface plate that rotates in one direction, a polishing pad attached to the rotating surface plate, and a polishing object that is rotated and held so that the surface to be polished faces the polishing surface of the polishing pad. In the polishing step, a holding plate having a diameter smaller than that of the rotary platen and a polishing liquid supply unit for supplying the polishing composition to a polishing portion of the polishing surface and the surface to be polished are provided. It is preferable to carry out polishing using a polishing apparatus provided with a liquid discharge mechanism for removing polishing waste liquid from the polishing surface into the polishing cover behind the polishing surface in the rotation direction of the rotary platen.

According to a method for polishing a metal film formed on a semiconductor substrate by using the metal polishing composition of the present invention using a polishing apparatus having a polishing pad, the polishing pad according to the present invention is used. Comprising a hole for supplying a metal polishing composition to the polishing pad surface, and The use of a polishing apparatus in which the chemical mechanical polishing apparatus includes a device for supplying the metal polishing composition of the present invention to the surface of the polishing pad through the hole of the polishing pad is advantageous in terms of polishing rate and dish suppression. preferable.

Example

Hereinafter, the present invention will be described based on examples.

The evaluation of the polishing performance of the polishing composition was performed by the following method.

Sales 8 inch wafer polishing machine (MAT-M1M manufactured by MAT-681M)

Polishing pad: Foamed polyurethane pad (IC1400A21 made by Dale Yutta)

Polishing composition supply rate: 200mlZ min

Relative speed between semiconductor wafer and polishing pad: 50mZ min

Polishing pressure: 70g / cm ²

Dressing: Before each polishing, the polishing was performed for 3 minutes using a No. 100 dresser under the conditions of a load of 30 gZcm ² and a relative speed between the dresser and the polishing pad of 50 mZ.

Using an 8-inch diameter semiconductor wafer with a 1 μm thick Cu film, polishing was performed for an arbitrary time under the above polishing conditions, and the change in metal film thickness before and after polishing was calculated by converting the electrical resistance value into a value. .

[0036] <Scratch evaluation>

After washing and drying the semiconductor wafer polished under the above-mentioned polishing conditions, a spotlight was applied to the surface of the semiconductor wafer in a dark room, and the degree of scratches on the entire surface of the semiconductor wafer was visually judged.

◎: not observed

〇: extremely low

△: less

X: Many

[0037] <Dating measurement>

Polish the wafer with pattern (SKW6-2 specification: Oxide film 0.8m, TaN25nm, Cul. 5m 8-inch wafer) under the above polishing conditions, and make line & space parts at 100m intervals. Using a desktop miniature probe microscope (Nanopics manufactured by Seiko Instruments), the amount of dicing on the Cu surface embedded in the space was measured, and the measurement results at any 10 locations were averaged. As for the evaluation of dating, the following index was used to indicate により -X. In this dishing evaluation, the time required to completely polish a predetermined film thickness was determined from the measured polishing rate, and the time 20% longer than that value (20% overpolishing) was defined as the polishing time.

◎: less than 20

〇: 20nm or more and less than 40nm

△: 40 nm or more and less than 80 nm

X: 80nm or more

[0038] <In-plane uniformity evaluation>

After cleaning and drying the silicon wafer polished under the above polishing conditions, a spotlight was applied to the wafer surface in a dark room, and the uniformity of the polished state of the entire wafer surface was visually determined. ◎: Very good uniformity

〇: Good uniformity

△: Partially uneven polishing state is confirmed

X: Poor uniformity

[0039] <Evaluation of storage stability>

The storage stability of the metal polishing composition after standing at room temperature for 6 months was evaluated as follows.

〇: Change rate of polishing rate and etching rate is less than 5%

△: Change rate of polishing rate and etching rate is 5% or more and less than 20%

X: Change rate of polishing rate and etching rate is 20% or more

Example 1

After dissolving 12 g of phosphorus vanadomolybdic acid (trade name: PVM-1-11 made by Nippon Inorganic Chemical Industry) as polyoxo acid in 187 g of water, dodecyl benzene sulfonic acid (trade name: Neoperex) is used as an aionic surfactant. GS made by Kao) After adding and mixing lg, water was added to dilute it three times to obtain a metal polishing composition. Table 1 shows the evaluation results. Example 2

After dissolving 12 g of phosphorus vanadomolybdic acid as polyoxo acid in 187 g of water, 0.5 g of dodecylbenzenesulfonic acid and 0.02 g of histidine (manufactured by Wako Pure Chemical Industries) are added and mixed as an aionic surfactant. Then, water was added and diluted three times to obtain a metal polishing composition. Table 1 shows the evaluation results.

Example 3

After dissolving 10 g of chemolybdic acid (trade name: SM Nippon Inorganic Chemical Industry) as polyoxo acid in 189 g of water, 0.4 g of dodecylbenzenesulfonic acid, 0.02 g of histidine and quinaldine are used as an aionic surfactant. Acid (manufactured by Wako Pure Chemical Industries) 0. Olg was added and mixed, and then water was added and diluted three times to obtain a metal polishing composition. The evaluation results are shown in Table 1.

After dissolving 12 g of phosphorus vanadotungstic acid (product name: PVW-1-11 manufactured by Nippon Inorganic Chemical Industry) as polyoxo acid in 167 g of water, 0.5 g of dodecyl benzene sulfonic acid and 0.03 g of histidine as an a-on surfactant. After adding and mixing 20 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.), water was added to dilute the mixture three times to obtain a metal polishing composition. Table 1 shows the evaluation results.

Example 5

After dissolving 12 g of phosphorus vanadomolybdic acid as polyoxo acid in 177 g of water, 0.5 g of dodecylbenzenesulfonic acid, 0.02 g of histidine, and polyethylene lendalicol (average molecular weight 8000 manufactured by Wako Pure Chemical Industries) After adding and mixing 10 g, water was added and diluted three times to obtain a metal polishing composition. Table 1 shows the evaluation results.

Example 6

After dissolving 12 g of phosphorus vanadomolybdic acid as polyoxo acid in 185 g of water, 0.5 g of dodecylbenzene sulfonic acid, 0.02 g of histidine, and 2 g of hydroxyethyl cellulose (manufactured by Wako Pure Chemical Industries) as an ionic surfactant. After adding and mixing, water was added and diluted three times to obtain a metal polishing composition. Table 1 shows the evaluation results.

Comparative Example 1 A polishing composition was obtained by simply dissolving 4 g of phosphorus vanadomolybdic acid in 196 g of water. Table 1 shows the evaluation results.

Comparative Example 2

A composition was obtained in exactly the same manner as in Example 5, except that the same amount of stearyltrimethylammonium-dimethyl chloride (trade name: Cotamine 86W, manufactured by Kao) was used as the cationic surfactant instead of the ionic surfactant. Table 1 shows the evaluation results. After leaving this polishing composition for one day, sedimentation of particles was confirmed.

Comparative Example 3

A solution obtained by dissolving 6 g of cunic acid (manufactured by Wako Pure Chemical Industries, Ltd.) in 162 g of water and dissolving 0.4 g of benzotriazole in 3 g of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added. Further, 60 g of colloidal silica (average particle diameter 40 nm, silica concentration 20%, manufactured by Nissan Chemical Industries, Ltd.) was added, and finally 28 g of hydrogen peroxide solution (manufactured by Wako Pure Chemical Industries, Ltd., 30% aqueous solution) was added, and the polishing composition was added. I adjusted things. Table 1 shows the evaluation results of this composition.

Comparative Example 4

Dissolve 12 g of phosphorus vanadomolybdic acid (PVM-1-11: trade name, manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) in 176 g of water as a polyoxoacid, and stir with a homogenizer, then synthesize polyoxyethylene as a nonionic surfactant. After adding 8 g of alcohol ether (BL AUNON DAL-5: trade name, manufactured by Aoki Yushi Kogyo Co., Ltd.), water was added to dilute it three times to obtain a polishing composition.

[table 1]

Polishing rate Scratch dishing In-plane uniformity Storage stability

(nm / min)

Example 1 1 2 0 0 No 〇〇〇 Example 2 1 0 7 0 No ◎ 〇例 Example 3 7 2 0 No 〇〇 Example 4 8 1 0 No ◎ 〇 Example 5 1 0 3 0 ◎ © 〇 Example 6 1 0 8 0 ◎ ◎ 〇 Comparative Example 1 3 8 0 0 XX 〇 Comparative Example 2 8 0 Δ Δ X Comparative Example 3 2 0 0 Yes XX Δ Comparative Example 4 4 1 0 Δ Δ X Industrial use Sex

According to the metal film polishing composition of the present invention, the problem that was difficult with the conventional technique of suppressing etching and dishing and polishing a metal film such as a copper film at high speed even under a low polishing pressure is solved. Can be achieved. The present invention has found a material having extremely useful performance in polishing a metal film on a semiconductor substrate, and its industrial utility value is extremely large.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view showing an example of forming a metal wiring using a CMP technique.

Claims

The scope of the claims

[1] A metal polishing composition comprising a polyoxoacid, an aionic surfactant and water.

[2] The metal polishing composition according to claim 1, wherein the polyoxo acid is a heteropoly acid.

3. The metal polishing composition according to claim 1, wherein the ionic surfactant is in an acid form.

[4] The metal polishing composition according to any one of [13] to [13], comprising a water-soluble polymer compound and Z or a polyhydric alcohol compound.

[5] The metal polishing composition according to any one of [14] to [14], further comprising an organic compound having a nitrogen atom and a carboxyl group in the molecule.

[6] The metal polishing composition according to claim 15, wherein the metal polishing composition is substantially free of munitions.

[7] The metal polishing composition according to any one of [16] to [16], wherein the metal polishing composition is substantially free of a nonionic surfactant.

[8] A method for polishing a metal film on a semiconductor substrate, comprising using the metal polishing composition according to claim 17.

[9] A method for producing a semiconductor substrate, comprising a polishing step using the metal polishing composition according to any one of claims 17 to 17.