JP2007214290A - Process for fabricating semiconductor integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for fabricating a semiconductor integrated circuit in which the surface of polished copper is clean even when a polishing liquid containing colloidal silica, where the surface exhibiting excellent polishing performance is covered at least partially with aluminum, as abrasive grains is employed. <P>SOLUTION: The process for fabricating a semiconductor integrated circuit comprises a step for polishing a substrate having a conductor film of copper or its alloy by using a polishing liquid containing colloidal silica, where the surface is covered at least partially with aluminum atom, as abrasive grains, and a cleaning step using a cleaning liquid containing quaternary ammonium salt, chelating agent having a carboxyl group, and a surfactant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor integrated circuit, and more particularly to polishing and subsequent cleaning methods in a wiring process of a semiconductor device.

In the development of a semiconductor device represented by a semiconductor integrated circuit (hereinafter referred to as LSI), in order to reduce the size and increase the speed, there is a demand for higher density and higher integration by miniaturization and lamination of wiring. LSIs using copper having low wiring resistance as a metal for wiring have been developed, and various techniques such as chemical mechanical polishing (hereinafter referred to as CMP) have been used as techniques for this purpose.
CMP is a technique for flattening the unevenness of the wafer surface caused by lamination. A general method is to attach a polishing pad on a circular polishing platen (platen) and immerse the polishing pad surface with a polishing liquid. Then, press the surface of the substrate (wafer) against the pad, apply a predetermined pressure (polishing pressure) from the back side, rotate both the polishing platen and the substrate, and the surface of the substrate is caused by the mechanical friction that occurs. Flattening.
A metal polishing liquid used in CMP generally contains abrasive grains (eg, alumina, silica) and an oxidizing agent (eg, hydrogen peroxide). The metal surface is oxidized with an oxidizing agent, and the oxide film is polished. It is thought that it is grind | polishing by removing with a grain.

However, when CMP is carried out using such a metal polishing liquid, polishing scratches (scratches), a phenomenon in which the entire polishing surface is polished more than necessary (thinning), the polishing metal surface is not flat, only the center. Phenomena that is deeply polished to produce dish-like dents (dishing), insulators between metal wires are polished more than necessary, and the surface of multiple metal wires forms dish-shaped recesses (erosion), etc. May occur. In particular, in recent years, there has been an increasing demand for reducing dishing for higher density and higher integration. In recent years, the diameter of wafers at the time of manufacturing LSIs has been increased in order to improve productivity. Currently, diameters of 200 mm or more are widely used, and manufacturing of 300 mm or more has started. With such an increase in size, the difference in polishing rate between the wafer center and the periphery has increased, and the demand for improvement in in-plane uniformity has increased.
In addition, the use of a polishing liquid containing solid abrasive grains provides a high polishing rate, but causes the aggregation of solid abrasive grains in the polishing liquid or removes the polishing liquid remaining on the surface to be polished after polishing. In addition, the cleaning process normally performed is complicated. Furthermore, in order to process the liquid after washing (waste liquid), there is a problem in terms of cost, for example, it is necessary to settle and separate solid abrasive grains.

In order to solve the problems of the polishing liquid containing solid abrasive grains as described above, colloidal silica in which at least a part of silicon atoms on the surface are covered with aluminum atoms (hereinafter referred to as “specific colloidal silica” as appropriate). .) Has been investigated as a solid abrasive. The specific colloidal silica has been confirmed to have a negative zeta potential at a pH of 7 or less, and the specific colloidal silica having such characteristics can stably exist without agglomerating with each other in the polishing liquid. By containing the specific colloidal silica in the liquid, an effect excellent in suppressing aggregation of solid abrasive grains is exhibited.
However, on the other hand, copper, which is the main polishing target of CMP, exists in the state of Cu ^{2+ in} an aqueous solution and is positively charged. Therefore, the specific colloidal silica is easily adsorbed on the copper surface. For this reason, when a polishing liquid containing specific colloidal silica is used and the cleaning liquid after the polishing process is performed by a conventional cleaning liquid or cleaning method, the specific colloidal silica remains on the polished surface after CMP, and this is obtained. May cause defects in the manufactured LSI.
JP 2001-127019 A

  Even if the object of the present invention made in consideration of the above problems is a case where a polishing liquid containing colloidal silica coated with aluminum at least part of the surface showing excellent polishing performance is used as an abrasive, It is an object of the present invention to provide a method for manufacturing a semiconductor integrated circuit in which a polished copper surface is clean.

As a result of intensive studies on the problems related to the cleaning of the polishing liquid after polishing, the present inventors have found that the problems can be solved by the following (1) to (3) and have achieved the problem.
That is, the present invention is as follows.
<1> a step of polishing a substrate having a conductor film made of copper or an alloy thereof using a polishing liquid containing abrasive particles of colloidal silica in which at least a part of the surface is covered with aluminum atoms, and a quaternary ammonium salt And a step of cleaning using a cleaning liquid containing a chelating agent having a carboxyl group and a surfactant.
<2> The method according to <1>, wherein the cleaning liquid contains an amine compound.
<3> The production method according to <1> or <2>, wherein the cleaning liquid contains an aliphatic carboxylic acid.

  According to the present invention, the polished copper surface is clean even when a polishing liquid containing colloidal silica coated with aluminum at least part of the surface exhibiting excellent polishing performance is used. A method for manufacturing a semiconductor integrated circuit can be provided.

Hereinafter, specific embodiments of the present invention will be described in the order of steps.
<Step of polishing a substrate having a conductor film made of copper or an alloy thereof with a polishing liquid using abrasive particles of colloidal silica whose at least part of the surface is covered with aluminum atoms>
The present invention comprises a step of polishing a substrate having a conductor film made of copper or an alloy thereof using a polishing liquid containing abrasive particles of colloidal silica having at least a part of the surface covered with aluminum atoms (hereinafter referred to as “ (Referred to as “first step”).
Below, the preferable composition and polishing method of the polishing liquid used in the first step will be described.

[Polishing liquid]
The polishing liquid used in the present invention contains the specific colloidal silica described below, and an organic acid, an oxidizing agent, a heterocyclic compound, and the like used in combination as necessary. Each component contained in the polishing liquid will be sequentially described.

(Specific colloidal silica with at least part of the surface covered with aluminum atoms)
The colloidal silica used in the present invention functions as abrasive grains in the polishing liquid of the present invention, and is hereinafter referred to as specific colloidal silica as appropriate in this specification.
In the present invention, “a colloidal silica in which at least a part of silicon atoms on the surface are substituted with aluminum atoms” means that aluminum atoms are present on the surface of the colloidal silica having a site containing a silicon atom having a coordination number of 4. A state in which an aluminum atom coordinated with four oxygen atoms is bonded to the surface of the colloidal silica, and a new surface in which the aluminum atom is fixed in a four-coordinate state is formed. Alternatively, it may be in a state in which silicon atoms existing on the surface are once extracted and a new surface is formed in which aluminum atoms are replaced.
The colloidal silica used for the preparation of the specific colloidal silica is more preferably a colloidal silica obtained by hydrolysis of alkoxysilane that does not contain impurities such as alkali metals inside the particles. The particle size of the colloidal silica used as a raw material is appropriately selected according to the purpose of use of the abrasive grains, but is generally about 10 to 200 nm.

As a method for obtaining a specific colloidal silica by substituting silicon atoms on the surface of such colloidal silica particles with an aluminum atom, for example, a method of adding an aluminate compound such as ammonium aluminate to a dispersion of colloidal silica is preferably used. This method is described in detail in Japanese Patent No. 3463328 and Japanese Patent Laid-Open No. 63-123807, and this description can be applied to the present invention.
As another method, a method of adding aluminum alkoxide to a dispersion of colloidal silica can be mentioned.
The aluminum alkoxide used here may be any, but is preferably aluminum isopropoxide, aluminum butoxide, aluminum methoxide, or aluminum ethoxide, and particularly preferably aluminum isopropoxide or aluminum butoxide.

  The specific colloidal silica is acidic in that the aluminosilicate site generated by the reaction between the tetracoordinate aluminate ion and the silanol group on the surface of the colloidal silica fixes a negative charge and gives the particle a large negative zeta potential. Is also excellent in dispersibility. Therefore, it is important that the specific colloidal silica produced by the method as described above exists in a state where an aluminum atom is coordinated to four oxygen atoms.

  Such a structure, that is, the occurrence of substitution of silicon atoms and aluminum atoms on the colloidal silica surface can be easily confirmed, for example, by measuring the zeta potential of the abrasive grains.

The amount of substitution of silicon atoms on the surface of colloidal silica with aluminum atoms is preferably such that the surface atom substitution rate (number of introduced aluminum atoms / number of surface silicon atom sites) of colloidal silica is 0.001% or more and 20% or less. Is from 0.01% to 10%, particularly preferably from 0.1% to 5%.
When the silicon atom on the surface of the colloidal silica is replaced with an aluminum atom, the substitution amount with the aluminum atom is controlled by controlling the addition amount (concentration) of an aluminate compound, aluminum alkoxide, etc. added to the colloidal silica dispersion. It can be appropriately controlled.

Here, the amount of aluminum atoms introduced into the colloidal silica surface (number of introduced aluminum atoms / number of surface silicon atom sites) is consumed from the unreacted aluminum compound remaining after the reaction among the aluminum compounds added to the dispersion. The amount of the obtained aluminum compound was calculated, assuming that they reacted 100%, the surface area converted from the colloidal silica diameter, the specific gravity of colloidal silica 2.2, and the number of silanol groups per unit surface area (5-8 pieces / nm ²⁾ it can be estimated from actual measurements obtained specific colloidal silica per se and elemental analysis, aluminum is not present inside the particles, assuming spread uniformly and thinly on the surface, the colloidal silica The surface area / specific gravity and the number of silanol groups per unit surface area are obtained.

As a specific production method, for example, colloidal silica is dispersed in water in the range of 1 to 50% by weight, a pH adjuster is added to the dispersion to adjust the pH to 7 to 11, and then at around room temperature, Add aqueous ammonium aluminate and stir at that temperature for 1-10 hours. Then, the method of removing an impurity by ion exchange, ultrafiltration, etc., and obtaining specific colloidal silica is mentioned.
The size (volume equivalent diameter) of the specific colloidal silica obtained is preferably 3 m to 200 nm, more preferably 5 nm to 100 nm, and particularly preferably 10 nm to 60 nm. In addition, the value measured by the dynamic light scattering method is employ | adopted for the particle size (volume equivalent diameter) of specific colloidal silica.

Of the abrasive grains contained in the polishing liquid used in the present invention, the weight ratio of the specific colloidal silica is preferably 50% or more, and particularly preferably 80% or more. All of the contained abrasive grains may be a specific colloidal silica.
The content of the specific colloidal silica in the polishing liquid at the time of use is preferably 0.001 wt% or more and 5 wt% or less, more preferably 0.01 wt% or more and 0.5 wt% or less, particularly preferably. It is 0.05 weight% or more and 0.2 weight% or less.

In addition to the specific colloidal silica, the polishing liquid used in the present invention can contain abrasive grains other than the specific colloidal silica as long as the effects of the present invention are not impaired. As the abrasive grains that can be used here, fumed silica, colloidal silica, ceria, alumina, titania and the like are preferable, and colloidal silica is particularly preferable.
The size of the abrasive grains other than colloidal silica in which at least part of the silicon atoms on the surface is covered with aluminum atoms is preferably equal to or more than twice that of the specific colloidal silica.

The polishing liquid used in the present invention preferably further contains other components.
(Oxidant)
The polishing liquid of the present invention preferably contains an oxidizing agent (a compound capable of oxidizing a metal to be polished).
Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, Examples thereof include dichromate, permanganate, ozone water, silver (II) salt, and iron (III) salt.

  Examples of iron (III) salts include inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III) and iron bromide (III), as well as organic iron (III) salts. Complex salts are preferably used.

  When an organic complex salt of iron (III) is used, examples of complex-forming compounds constituting the iron (III) complex salt include acetic acid, citric acid, oxalic acid, salicylic acid, diethyldithiocarbamic acid, succinic acid, tartaric acid, glycolic acid, glycine , Alanine, aspartic acid, thioglycolic acid, ethylenediamine, trimethylenediamine, diethylene glycol, triethylene glycol, 1,2-ethanedithiol, malonic acid, glutaric acid, 3-hydroxybutyric acid, propionic acid, phthalic acid, isophthalic acid, 3 Aminopolycarboxylic acid and its salt are mentioned other than -hydroxy salicylic acid, 3,5-dihydroxy salicylic acid, gallic acid, benzoic acid, maleic acid, etc. and these salts.

  Aminopolycarboxylic acids and salts thereof include ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid, , 2-Diaminopropane-N, N, N ′, N′-tetraacetic acid, ethylenediamine-N, N′-disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylate ethyl) ) -L-aspartic acid, N- (carboxymethyl) -L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, cyclohexanediaminetetraacetic acid, iminodiacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine 1-N, N′-diacetic acid, ethylenediamine orthohydroxyphenylacetic acid, N, N-bis (2-hydroxybenzidine ) Ethylenediamine -N, N-diacetic acid and salts thereof. The kind of the counter salt is preferably an alkali metal salt or an ammonium salt, and particularly preferably an ammonium salt.

Among these, hydrogen peroxide, iodate, hypochlorite, chlorate, persulfate, and organic complex salts of iron (III) are preferable, and preferable complex-forming compounds when using an organic complex salt of iron (III) Is citric acid, tartaric acid, aminopolycarboxylic acid (specifically, ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid, ethylenediamine-N, N′-disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylateethyl) -L-aspartic acid, N- (carboxymethyl) -L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).
Of the oxidizing agents, hydrogen peroxide is most preferred.

  The addition amount of the oxidizing agent is preferably 0.003 mol to 8 mol, more preferably 0.03 mol to 6 mol, and more preferably 0.1 mol to 4 mol in 1 L of the polishing liquid used for polishing. Is particularly preferred. That is, the addition amount of the oxidizing agent is preferably 0.003 mol or more from the viewpoint of sufficient metal oxidation and ensuring a high CMP rate, and is preferably 8 mol or less from the viewpoint of preventing roughening of the polished surface.

(Organic acid)
The polishing liquid of the present invention preferably contains an organic acid separately from the oxidizing agent. The organic acid here is a compound different from an oxidizing agent for oxidizing a metal.
The organic acid is preferably water-soluble, and is an amino acid or other acid. As the amino acid, one selected from the following group is more suitable.
Glycine, L-alanine, β-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L-proline, Sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-tyrosine, 3,5-diodo-L-tyrosine, β- (3 4-Dihydroxyphenyl) -L-alanine, L-thyroxine, 4-hydroxy-L-proline, L-cystine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-aspartic acid, L-glutamic acid And amino acids such as S- (carboxymethyl) -L-cysteine and 4-aminobutyric acid.
As organic acids other than amino acids, those selected from the following group are more suitable.
Formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid , N-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, Examples thereof include tartaric acid, citric acid, lactic acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, dihydroxyethylglycine, and salts such as ammonium salts and alkali metal salts thereof. Among these, malic acid, tartaric acid, citric acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, dihydroxyethylglycine and the like are preferable in that the etching rate can be effectively suppressed while maintaining a practical CMP rate. Is preferred.

  The addition amount of the organic acid is preferably 0.0005 to 0.5 mol, more preferably 0.005 mol to 0.3 mol, and more preferably 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. The amount is particularly preferably 0.1 mol. That is, the amount of acid added is preferably 0.5 mol or less from the viewpoint of suppressing etching, and 0.0005 mol or more is preferable for obtaining a sufficient effect.

(Heterocyclic compound)
The polishing liquid used in the present invention preferably contains a heterocyclic compound as a compound that forms a passive film on the metal surface to be polished.
A “heterocyclic compound” is a compound having a heterocycle containing a heteroatom.

  The number of heteroatoms contained in the compound having a heterocycle is not limited, but is preferably 2 or more, more preferably 4 or more heteroatoms. In particular, it is preferable to use a heterocyclic compound containing 3 or more nitrogen atoms, and using a heterocyclic compound containing 4 or more nitrogen atoms is preferable because the remarkable effects of the present invention can be obtained.

  Further, the heterocyclic ring may be a single ring or a polycyclic ring having a condensed ring. The number of members in the case of a single ring is preferably 5 to 7, particularly preferably 5. When it has a condensed ring, the number of rings is preferably 2 or 3.

Specific examples of these heterocyclic rings include the following.
Imidazole ring, pyrazole ring, oxazole ring, isoxazole ring, pyridine ring, imidazolidine ring, piperidine ring, piperazine ring, morpholine ring, chroman ring, thiochroman ring, isochroman ring, indoline ring, indolidine ring, indazole ring, quinolidine ring , Isoquinoline ring, quinoline ring, naphthyridine ring, quinazoline ring, acridine ring, perimidine ring, phenanthroline ring, carbazole ring, phenazine ring, anti-lysine ring, oxadiazole ring, triazole ring, tetrazole ring, benzimidazole ring, benzoxazole ring Benzthiazole ring, benzthiadiazole ring, benzfuroxane ring, naphthimidazole ring, benztriazole ring, tetraazaindene ring, etc., more preferably triazole ring, Tetrazole ring.

Examples of the substituent that can be introduced into the heterocyclic compound used in the present invention include the following.
Examples of the substituent that the heterocyclic ring may have include a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, and a heterocyclic group. Further, a plurality of substituents may be bonded to each other to form a ring.

Specific examples of the heterocyclic compound that can be particularly preferably used in the present invention include, but are not limited to, the following.
That is, 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1,2,3-triazole, 4- Amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino- 1,2,4-triazole and benzotriazole.

  The total amount of the heterocyclic compound used in the present invention is the polishing liquid used for polishing (that is, the diluted polishing liquid when diluted with water or an aqueous solution). In 1 L) is preferably 0.0001 to 0.1 mol, more preferably 0.0005 to 0.05 mol, and still more preferably 0.0005 to 0.01 mol.

(Chelating agent)
The polishing liquid of the present invention may contain a chelating agent as necessary in order to reduce adverse effects such as mixed polyvalent metal ions. As a chelating agent, a general-purpose hard water softening agent that is a precipitation inhibitor of calcium or magnesium or an analogous compound thereof can be used, and two or more of these may be used in combination as necessary.

  The addition amount of the chelating agent may be an amount sufficient to sequester metal ions such as mixed polyvalent metal ions, for example, 0.0003 mol to 0.07 mol in 1 L of a polishing liquid used for polishing. Add to be.

(PH adjuster)
The polishing liquid of the present invention is preferably added with an alkali / acid or a buffer so as to have a predetermined pH.
Examples of alkali / acid or buffering agents include organic ammonium hydroxides such as ammonium hydroxide and tetramethylammonium hydroxide, non-metallic alkaline agents such as alkanolamines such as diethanolamine and triethanolamine, sodium hydroxide, water Alkali metal hydroxides such as potassium oxide and lithium hydroxide, inorganic acids such as nitric acid, sulfuric acid and phosphoric acid, carbonates such as sodium carbonate, phosphates such as trisodium phosphate, borate and tetraborate Preferred examples include hydroxybenzoate and the like. Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkali / acid or the buffer may be an amount that maintains the pH within a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of the polishing liquid when used for polishing. More preferably, it is 0.003 mol to 0.5 mol.

  The pH of the polishing liquid when used for polishing is preferably from 3 to 12, more preferably from 4 to 9, and particularly preferably from 5 to 8. Within this range, the metal liquid of the present invention exhibits particularly excellent effects.

(Surfactant / Hydrophilic polymer)
The polishing liquid of the present invention preferably contains a surfactant and a hydrophilic polymer.
Both the surfactant and the hydrophilic polymer have an action of reducing the contact angle of the surface to be polished and promoting uniform polishing. As the surfactant and the hydrophilic polymer used, those selected from the following groups are suitable.
Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. Examples of the cationic surfactant include aliphatic amine salt, aliphatic quaternary ammonium salt, benzalkonium chloride. Salt, benzethonium chloride, pyridinium salt, imidazolinium salt, and amphoteric surfactants include carboxybetaine type, aminocarboxylate, imidazolinium betaine, lecithin, alkylamine oxide, nonionic interface Examples of the activator include an ether type, an ether ester type, an ester type, and a nitrogen-containing type, and also include a fluorine-based surfactant.
Furthermore, examples of the hydrophilic polymer include polyglycols such as polyethylene glycol, polysaccharides such as polyvinyl alcohol, polovinyl pyrrolidone, and alginic acid, and carboxylic acid-containing polymers such as polymethacrylic acid.

  Of the above, the acid or its ammonium salt is preferably free from contamination by alkali metals, alkaline earth metals, halides and the like.

  The weight average molecular weight of these surfactants and hydrophilic polymers is preferably from 500 to 100,000, particularly preferably from 2,000 to 50,000.

  The total amount of the surfactant and / or hydrophilic polymer added is preferably 0.001 to 10 g and more preferably 0.01 to 5 g in 1 L of a polishing liquid used for polishing. It is particularly preferably 0.1 to 3 g.

[Polishing method]
The workpiece to be polished in the polishing method of the present invention includes a wafer having a conductive material film formed on a support substrate, and an interlayer insulating film provided on a wiring formed on the support substrate. Examples include materials at all stages that require planarization in a semiconductor device manufacturing process, such as a laminate in which a conductive material film is formed.

(Wiring metal material)
A workpiece to be polished according to the present invention is an LSI having wiring made of copper or a copper alloy, and among copper alloys, a copper alloy containing silver is suitable. The silver content contained in the copper alloy exhibits an excellent effect at 10% by mass or less, further 1% by mass or less, and the most excellent effect in the copper alloy in the range of 0.00001 to 0.1% by mass. Demonstrate.

(Wiring thickness)
The workpiece to be polished according to the present invention is, for example, a DRAM device system having a half pitch of 0.15 μm or less, particularly 0.10 μm or less, more preferably 0.08 μm or less, while MPU device system is 0.12 μm. In the following, an LSI having a wiring of 0.09 μm or less, more preferably 0.07 μm or less is preferable. The polishing liquid of the present invention exhibits particularly excellent effects on these LSIs.

(Barrier metal)
The workpiece to be polished according to the present invention is provided with a barrier layer for preventing copper diffusion between the copper wiring and the interlayer insulating film. As the barrier layer, a low resistance metal material such as TiN, TiW, Ta, TaN, W, and WN are preferable, and Ta and TaN are particularly preferable.

(Insulating film)
An object to be processed according to the present invention can be applied with an inorganic insulating film or an organic insulating film as an insulating film. As a method for manufacturing the inorganic insulating film, a constant pressure CVD method, a plasma CVD method, or the like can be given. In the organic system, there are a coating type insulating film mainly composed of a hydrolyzed product of tetraalkoxylane, and an interlayer insulating film having a low relative dielectric constant mainly composed of polyorganosiloxane called organic SOG.

(Polishing equipment)
A polishing apparatus capable of carrying out the present invention has a general polishing surface plate having a holder for holding a semiconductor substrate or the like having a workpiece and a polishing pad (with a motor capable of changing the number of rotations attached). A polishing apparatus can be used and is not particularly limited as long as it can polish a wafer having a diameter of 300 mm. For example, FREX300 (Ebara Corporation) can be used.

(Polishing liquid supply method)
In the present invention, while polishing the target metal, the polishing liquid is continuously supplied to the polishing pad on the polishing surface plate by a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid.

  In the present invention, the concentrated polishing liquid can be diluted with water or an aqueous solution. Examples of the dilution method include a method in which a pipe for supplying a concentrated polishing liquid and a pipe for supplying water or an aqueous solution are mixed and mixed in the middle, and the diluted polishing liquid is supplied to a polishing pad. it can. In this case, mixing is a method in which liquids collide with each other through a narrow passage with pressure applied, a method in which a filling such as a glass tube is filled in the piping, a flow of liquid is separated and separated, and piping is repeated. A commonly used method such as a method of providing a blade rotating with power can be used.

Further, as another dilution method, a pipe for supplying a polishing liquid and a pipe for supplying water or an aqueous solution are provided independently, and a predetermined amount of liquid is supplied from each to the polishing pad, and the relative motion between the polishing pad and the surface to be polished is provided. The method of mixing by the above can also be used in the present invention.
Furthermore, a method in which a predetermined amount of concentrated polishing liquid and water or an aqueous solution are mixed in one container, mixed, diluted to a predetermined concentration, and then supplied to the polishing pad can be applied to the present invention. I can do it.

In addition to these methods, the method in which the component to be contained in the polishing liquid is divided into at least two components, and when these are used, water or an aqueous solution is added to the polishing pad and supplied to the polishing pad is also used in the present invention. I can do it. In this case, it is preferable to divide and supply the component containing an oxidizing agent and the component containing an acid.
For example, an oxidant is one component (A), an acid, an additive, a surfactant, and water are one component (B). The component (B) is diluted before use. In this case, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are necessary, and the three pipes are connected to one pipe for supplying the polishing pad, It may be mixed, or two pipes may be combined and then another one pipe may be combined and mixed. For example, a component containing a hard-to-dissolve additive and other components are mixed, a mixing path is lengthened to ensure a dissolution time, and then a polishing liquid is supplied by combining a pipe of water or an aqueous solution. It is also possible.
Further, the above three pipes may be led to the polishing pad and mixed and supplied by the relative movement of the polishing pad and the surface to be polished. After mixing the three components in one container, the mixed solution is supplied. You may supply to a polishing pad. Further, the polishing liquid may be a concentrated liquid, and the diluted water may be separately supplied to the polishing surface.

(pad)
The polishing pad used when the chemical mechanical polishing method is carried out using the polishing liquid of the present invention is not particularly limited, and may be a non-foam pad or a foam pad. The former uses a hard synthetic resin bulk material like a plastic plate for a pad. Further, the latter further includes three types of a closed foam (dry foam system), a continuous foam (wet foam system), and a two-layer composite (laminated system), and a two-layer composite (laminated system) is particularly preferable. Foaming may be uniform or non-uniform.
Further, it may contain abrasive grains (for example, ceria, silica, alumina, resin, etc.) used for polishing. In addition, the hardness may be either soft or hard, and either may be used. In the laminated system, it is preferable to use a different hardness for each layer. The material is preferably non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate or the like. In addition, the surface contacting the polishing surface may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

<Washing step using a cleaning solution containing a quaternary ammonium salt, a chelating agent having a carboxyl group, and a surfactant>
In the production method of the present invention, after the first step, a step of washing with a washing solution containing a quaternary ammonium salt, a chelating agent having a carboxyl group and a surfactant (hereinafter referred to as “second step” as appropriate). )including.
Below, the preferable composition and washing | cleaning method of the washing | cleaning liquid used at a 2nd process are demonstrated.

[Cleaning liquid]
The cleaning liquid after polishing using the polishing liquid is a cleaning liquid containing a quaternary ammonium salt, a chelating agent having a carboxyl group, a surfactant, and water or an aqueous solvent. The above cleaning solution is diluted 5 to 100 times, preferably 10 to 30 times.

(Quaternary ammonium salt)
The cleaning liquid used in the second step of the present invention contains a quaternary ammonium salt.
Examples of the quaternary ammonium salt include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, choline, and the like, and examples of the cleaning liquid component include at least one of the above substances and salts thereof. it can.
Among these, tetramethylammonium hydroxide is particularly preferable.

  The content of the quaternary ammonium salt is preferably 0.5 to 5% by weight with respect to the total weight of the cleaning liquid.

(Chelating agent having carboxyl group)
Examples of the chelating agent having a carboxyl group include nitrotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and the like, or a mixture thereof.
Among these, ethylenediaminetetraacetic acid is particularly preferable.

  The content of the chelating agent having a carboxyl group is preferably 0.1 to 5% by weight, more preferably 0.2 to 2% by weight, based on the total weight of the cleaning liquid.

(Surfactant)
Surfactants can include cations, nonionic surfactants or mixtures thereof.
Examples of the cationic surfactant include surfactants such as alkylamino salts and alkylammonium salts.
Nonionic surfactants include ethylene oxide addition polymer type, and ethylene oxide addition polymer type nonionic surfactants include poly (oxyethylene) -poly (oxypropylene) block copolymers, polyoxyethylene alkyl ethers, polyoxyethylenes. Examples thereof include oxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene hydrogenated castor oil body, and the like. Preferred nonionic surfactants include polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene decyl pentadecyl ether, polyoxyethylene Ethylene behenyl ether, polyoxyethylene decyl tetradecyl ether, polyoxyethylene cholesteryl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene hexyl decyl ether, ethylene glycol monostearyl acid , Polyethylene glycol monostearate, polyoxyethylene isostearate Lyseryl, polyoxyethylene glyceryl triisostearate, polyethylene glycol isostearate, polyethylene glycol monooleate, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glyceryl monostearate, polyoxyethylene glyceryl tristearate, polyoxyethylene tristearic acid Trimethylolpropane, polyoxyethylene isostearic acid trimethylolpropane, polyoxyethylene hydrogenated castor oil, polyoxyethylene hydrogenated castor oil isostearate, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil laurate, sorbitan fatty acid ester, mono fatty acid Glycerin, pyroglutamate, polyethylene glycol alkyl ether, polyethylene Glycol fatty acid esters, propylene glycol fatty acid esters, sorbitan fatty acid esters, fatty acid monoglycerides and the like.

  The content of the surfactant is preferably 0.1 to 5% by weight, more preferably 0.2 to 2% by weight, based on the total weight of the cleaning liquid.

  In the present invention, an amine compound and an aliphatic carboxylic acid are preferably contained in addition to the above three components.

(Amine compound)
The cleaning liquid used in the second step of the present invention preferably contains an amine compound from the viewpoint of cleaning effect, a small amount of metal residue, and economical efficiency.
Hydroxylamine, monoethanolamine, diethanolamine, triethanolamine, propanolamine, dipropanolamine, tripropanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, butanolamine, N-methylethanolamine, N-methyldiethanolamine, N , N-dimethylaminoethanol, N-ethylethanolamine, N-ethyldiethanolamine, N, N-diethylethanolamine, Nn-butylethanolamine, di-n-butylethanolamine and the like and at least one of its salts Can be mentioned.
The content of the amine compound is preferably 0.1 to 10% by mass with respect to the total weight of the cleaning liquid,
0.2-5 mass% is more preferable.

(Aliphatic carboxylic acid)
The cleaning liquid used in the second step of the present invention preferably contains an aliphatic carboxylic acid compound from the viewpoints of detergency and economy.
Examples of the aliphatic carboxylic acid include lactic acid, malic acid, tartaric acid, citric acid and the like, or a mixture thereof.
0.1-10 mass% is preferable with respect to the total weight of a washing | cleaning liquid, and, as for content of aliphatic carboxylic acid, 0.2-5 mass% is more preferable.

  The cleaning liquid used in the present invention is prepared by dissolving the above components in water or an aqueous solvent. This cleaning liquid can contain other additives such as hydrogen peroxide as long as the effects of the present invention are not impaired.

[Cleaning method]
In the cleaning step of the present invention, the polished object after polishing is thoroughly cleaned in running water, and then water droplets adhering to the processed object are removed using a spin dryer or the like and then dried. After the workpiece is dried, use the diluted cleaning liquid by adding water or an aqueous solution to the concentrated cleaning liquid, or combine the pipe for supplying the concentrated cleaning liquid and the pipe for supplying the water or aqueous solution together in the middle to mix. A method of supplying the diluted cleaning liquid to the wafer can be used. In this case, mixing is a method in which liquids collide with each other through a narrow passage with pressure applied, a method in which a filling such as a glass tube is filled in the piping, a flow of liquid is separated and separated, and piping is repeated. It is supplied by a conventional method such as a method of providing blades that rotate with power.

  When the workpiece after polishing is cleaned using the cleaning liquid, the abrasive grains can be more effectively removed as compared with the conventional cleaning liquid.

(Preparation of specific colloidal silica (A-1 to A-2))
Ammonia water was added to 1000 g of a 20% by weight aqueous dispersion of colloidal silica having an average abrasive grain size of 5, 50, and 200 nm to adjust the pH to 9.0, and then the Al ₂ O ₃ concentration was adjusted with stirring at room temperature. 15.9 g of an aqueous sodium aluminate solution having a 6 wt% Na ₂ O / Al ₂ O ₃ molar ratio of 1.50 was slowly added and stirred for 0.5 hour. The obtained sol was placed in a SUS autoclave apparatus, heated at 130 ° C. for 4 hours, and then filled with a hydrogen-type strongly acidic cation exchange resin (Amberlite IR-120B) and a hydroxyl group-type strongly basic anion exchange resin ( Amberlite IRA-410) was passed at room temperature at a space velocity of 1 h ⁻¹ , and the initial distillation was cut (A-1).
Alternatively, a space velocity of 1 h ^{− is applied} to a column packed with a hydrogen-type strongly acidic cation exchange resin (Amberlite IR-120B) and a hydroxyl group-type strongly basic anion exchange resin (Amberlite IRA-410) without performing heat treatment. ¹ was passed at room temperature, and the initial distillation was cut (A-2).
Abrasive grains A-1 to A-2 shown in Table 1 were prepared by the above method. The abrasive grains A-1 to A-2 did not show thickening or gelation after preparation.

(Preparation of polishing liquid)
Using the specific colloidal silica obtained as described above as abrasive grains, a polishing liquid having the composition shown below was used to polish a substrate for evaluation after cleaning.
-Composition of polishing liquid-
Specific colloidal silica: A-1 0.1% by mass
Oxidizing agent: 1% by mass of hydrogen peroxide
Organic acid: Glycine 10g / L
Heterocyclic compound: benzotriazole 0.05 g / L
Add pure water, total volume 1000mL
pH (adjusted with ammonia water and sulfuric acid) 9.0

An apparatus “LGP-613” manufactured by Lapmaster was used as a polishing apparatus, and the film provided on each wafer was polished under the following conditions while supplying a polishing liquid.
Base: Silicon wafer table with 8 inch copper film Rotation speed: 50 rpm
Head rotation speed: 50 rpm
Polishing pressure: 168 hPa
Polishing pad: Part number IC-1400 manufactured by Rodel Nitta Co., Ltd.
Slurry supply rate: 200 ml / min

<Example 1>
(Adjusting the cleaning solution)
The cleaning liquid of the present invention was prepared according to the following composition.
-Composition of cleaning solution-
Quaternary ammonium salt: tetramethylammonium hydroxide 1.5% by mass
Chelating agent having a carboxyl group: 1% by mass of ethylenediaminetetraacetic acid
Surfactant: Polyoxyethylene alkyl ether 2% by mass
Solvent: water 95.5% by mass
As a cleaning method of the example, cleaning was performed using a solution diluted with a ratio of (cleaning composition) :( distilled water) = 1: 20.
-Cleaning test with cleaning solution-
A cleaning test was performed by cleaning the polishing substrate using the cleaning solution. The cleaning was performed by scrub cleaning in which a PVA roll brush was brought into contact with a scrub part incorporated in a wafer cleaning machine manufactured by MAT, ZAB8W2M. The cleaning liquid is allowed to flow at 650 ml / min on the upper side of the polishing substrate xx and at 500 ml / min on the lower side for 25 seconds, and then pure water (deionized water) is supplied at 650 ml / min on the upper side of the polishing substrate 1 and 35 at 500 ml / min on the lower side. The sample was run for 2 seconds, and further processed for 30 seconds with a spin dry device built in the above device.

<Examples 2-3 and Comparative Examples 1-2>
In the same manner as in Example 1, cleaning liquids of Examples 2 and 3 and Comparative Examples 1 and 2 were prepared, and the workpiece after polishing was cleaned. The dilution rate was the same as in Example 1.

(Evaluation of surface condition after cleaning)
Further, the polished wafer was washed under the following conditions, and the surface state of the polished wafer after washing was evaluated by SEM observation.
As an evaluation method, when the surface state after cleaning was observed with a scanning electron microscope, “◯” was evaluated when a watermark of 50 μm or more was not observed, and “X” was evaluated when observed.
Examples and evaluation results of the cleaning liquid are shown below.

  It was found that when the cleaning liquid prepared in Examples 1 to 3 was used, foreign matters could be effectively removed. On the other hand, when using a cleaning solution made with ammonium hydroxide / hydrogen peroxide / water and hydrochloric acid / hydrogen peroxide / water, which is a conventional cleaning technique, foreign matter remaining on the wafer was found by SEM observation. .

Claims (3)

  A step of polishing a substrate having a conductor film made of copper or an alloy thereof using a polishing liquid having abrasive grains of colloidal silica whose at least part of the surface is covered with aluminum atoms, a quaternary ammonium salt, a carboxyl group And a step of cleaning with a cleaning solution containing a chelating agent having a surfactant and a surfactant.   The manufacturing method according to claim 1, wherein the cleaning liquid contains an amine compound.   The manufacturing method according to claim 1, wherein the cleaning liquid contains an aliphatic carboxylic acid.