JP2009218288A - Polishing solution and chemical mechanical polishing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing solution with which a polyimide film on a semiconductor substrate is polished fast while damage such as a scratch is suppressed to achieve high flatness after the polishing, and a chemical mechanical polishing method using the same. <P>SOLUTION: In manufacture of a semiconductor device, the polishing solution is used for chemical mechanical polishing mainly on a polyimide film substrate or a film substrate consisting essentially of polyimide, and contains (a) abrasive grains, (b) alcohols, and (c) alkanolamine, and (d) an alkaline compound, wherein the pH is ≥8. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyimide film polishing liquid used when performing chemical mechanical planarization in a semiconductor device manufacturing process, and a polishing method using the same. In particular, it is useful for a polishing process of a substrate made of a polyimide film used in a semiconductor package stacking process.

In the development of semiconductor devices typified by semiconductor integrated circuits (hereinafter sometimes referred to as “LSI”), in order to increase the integration and speed of semiconductor devices, wiring miniaturization and lamination methods are studied. Has been.
As a technology for this purpose, chemical mechanical polishing (Chemical Mechanical Polishing)
Polishing, hereinafter referred to as “CMP”. Etc.) are employed.
CMP is used to polish an interlayer insulating film (such as SiO ₂ ) or a metal thin film used for wiring to smooth the substrate or remove an excess metal thin film during wiring formation (for example, patents). Reference 1).

A general method of CMP is as follows.
A polishing pad is affixed on a circular polishing platen (platen), and the surface of the polishing pad is immersed in a polishing liquid. The surface of the substrate (wafer) is pressed against the polishing pad, and both the polishing surface plate and the substrate are rotated with a predetermined pressure (polishing pressure) applied from the back surface.
In CMP, the surface of the substrate is flattened by mechanical friction generated by the above operation.

A polyimide film or a film containing polyimide as a main component is also applied to a semiconductor package as described in, for example, Electronic Components and Technology Conference, 2006, Proceedings. (56th Publicant Date: 30 May-2 June 2006). However, such an organic polymer substrate is difficult to etch.
Regarding the etching of the polyimide resin, a method of wet etching using a solution containing hydrazine as a main component (for example, see Patent Documents 2 and 3) or an etching method using potassium hydroxide (for example, see Patent Document 4). ) And a method of irradiating laser, infrared rays, and microwaves during etching (see, for example, Patent Documents 5 to 7).
However, in the improvement example of the normal wet etching method, even if the above measures are taken, the etching takes a very long time, there is a problem in throughput, and etching unevenness occurs, resulting in flatness after etching. There are many things that are bad in nature and have not yet reached a satisfactory level for practical use.

As another method, a method is disclosed in which an abrasive such as alumina is added, a polishing liquid is spray-added, discharged onto the polyimide film surface at a high pressure, and etched (see, for example, Patent Documents 8 and 9). ).
Even when the polyimide film is etched by such a method of mixing an abrasive and discharging a polishing liquid, the etching varies depending on the angle of discharge, which may impair flatness and scratches.
In the case of a polyimide resin substrate, as described above, there is a problem of throughput in wet etching, and polishing unevenness may occur when spraying a polishing liquid, and in dry etching, there is a problem in flatness and film surface roughness. In any case, it has been difficult to achieve satisfactory flattening without causing a scratch problem.
US Pat. No. 4,944,836 Japanese Patent Laid-Open No. 3-101228 JP-A-5-202206 JP-A-5-301981 Japanese Patent Laid-Open No. 2002-20513 JP 2002-53684 A JP 2002-128922 A JP 2002-307111 A JP 2003-8171 A

  In light of the background of these prior arts, the present invention provides a polishing liquid capable of polishing a polyimide film on a semiconductor substrate in a short time, maintaining high flatness and without scratches such as scratches, and polishing using the same. It is intended to provide a method.

As a result of intensive studies, the present inventor has found that the above problems can be solved by the following polishing liquid and a polishing method using the same, and have completed the present invention.
The polishing liquid of the present invention and the polishing method using the same are as follows.
<1> A polishing liquid used for chemical mechanical polishing of a polyimide film substrate or a film substrate mainly composed of polyimide in the manufacture of a semiconductor device, wherein (a) abrasive grains, (b) alcohols, and (c) A polishing liquid containing alkanolamine and (d) an alkaline compound and having a pH of 8 or more.
<2> The polishing liquid according to <1>, further comprising (e) a metal anticorrosive.
<3> The polishing liquid according to <1> or <2>, further comprising (f) an oxidizing agent.

<4> The polishing liquid according to any one of <1> to <3>, wherein the alcohol (b) is a lower alcohol.
<5> The polishing liquid according to any one of <1> to <4>, wherein (b) the alcohol is glycol.
<6> The polishing liquid according to <5>, wherein the glycol is selected from ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, polyethylene glycol, and a mixture thereof.
<7> The (c) alkanolamine is selected from monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, ethyleneamine and a mixture thereof. The polishing liquid according to any one of <1> to <6>.
<8> In semiconductor device manufacturing, a substrate made of a polyimide film or a film containing polyimide as a main component is chemically and mechanically polished using the polishing liquid according to any one of <1> to <7>. A polishing method characterized by the above.

According to the present invention, it is possible to provide a polishing liquid capable of polishing a polyimide film on a semiconductor substrate in a short time, maintaining high flatness, and without scratches such as scratches.
Moreover, with the polishing liquid of the present invention, a polyimide film on a semiconductor substrate can be polished at a high speed while suppressing generation of polishing flaws, and a polishing method capable of achieving high flatness can be provided.

Hereinafter, specific embodiments of the present invention will be described.
<Polyimide film>
First, a polyimide film that is an object to be polished by the polishing liquid of the present invention will be described.
As the polyimide film, any polyimide film such as thermosetting, thermoplastic, and photosensitive can be used.
The polyimide film in the present invention is not particularly limited as long as it is a polyimide film formed on a substrate surface on which wiring can be formed, and may be a film formed by applying a resin liquid on a wafer, or may be formed in advance. A film formed by laminating a formed polyimide film or a film formed by adhering a polyimide film formed in advance with an epoxy adhesive or the like to the substrate surface may be used.
Specific examples of polyimide films include Electronic Components and Technology Conference, 2006. Proceedings. Examples include, but are not limited to, polyimides described in (56th Public Date: 30 May-2 June 2006), polyimide films described in JP-A-2002-20513, and the like.

The polishing liquid of the present invention for polishing the polyimide film contains (a) abrasive grains, (b) alcohols, (c) alkanolamine, and (d) an alkaline compound, and has a pH of 8 or more. It is a certain alkaline liquid (slurry).
Hereinafter, each component contained in the polishing liquid of the present invention will be described.

<(A) Abrasive grain>
The polishing liquid of the present invention contains abrasive grains. Preferable abrasive grains include, for example, silica (precipitated silica, fumed silica, colloidal silica, synthetic silica), ceria, alumina, titania, zirconia, germania, manganese oxide, diamond, etc., silica, alumina, manganese oxide, etc. Is preferably used, and alumina is more preferably used.

The average particle size (primary particle size) of the abrasive grains contained in the polishing composition of the present invention is preferably in the range of 5 to 1000 nm, more preferably 10 to 800 nm. Particles of 20 nm or more are preferred for the purpose of achieving a sufficient polishing speed. The particle diameter is preferably 700 nm or less for the purpose of preventing excessive frictional heat during polishing.
In addition, the value measured by the BET specific surface area method is used for the average particle diameter (primary particle diameter) of an abrasive grain here.

  The abrasive grains in the present invention can be used in combination with not only the above-described general-purpose inorganic abrasive grains but also organic abrasive grains composed of organic polymer particles as long as the effects of the present invention are not impaired. In addition, colloidal silica surface-modified with aluminate ions or borate ions, colloidal silica with controlled surface potential, colloidal silica with various surface treatments, composite abrasive grains made of multiple materials, etc. It is also possible to use it accordingly.

Although the addition amount of the abrasive grain in this invention is suitably selected according to the objective, generally it can be used in 0.01-80 mass% with respect to the total mass of polishing liquid. In the present invention, although the polishing rate increases as the amount of abrasive grains increases, the addition amount of abrasive grains is preferably 0.1 to 70% by mass from the viewpoint of suppressing scratches caused by the abrasive grains. 0.2 to 60% by mass is more preferable.
Two or more kinds of the above-mentioned abrasive grains can be used in combination. Depending on the purpose, the same kind of abrasive grains of different sizes can be combined, or different kinds of abrasive grains can be mixed and used. is there.

<(B) Alcohols>
The polishing composition of the present invention contains alcohols. Alcohols are largely classified into lower alcohols and higher alcohols. However, since the polishing liquid of the present invention is preferably an aqueous polishing liquid, lower alcohols are preferable from this viewpoint.
Examples of the lower alcohol include, but are not limited to, methanol, ethanol, isopropyl alcohol, glycerin, glycol and the like. Of these, glycol is preferred.
As the glycol, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, polyethylene glycol and the like can be used, and ethylene glycol, propylene glycol, polyethylene glycol and the like can be preferably used.
One kind of these alcohols may be contained in the polishing liquid, or two or more kinds thereof may be mixed and used as a mixture. When a mixture of a plurality of species is used, it is preferable to select those having good compatibility with each other.
As a usage-amount, it is preferable to use in the range of 1-60 mass%, It is more preferable to use in the range of 3-50 mass%, More preferably, it is the range of 5-50 mass%. More preferably it is used. Moreover, the said usage-amount represents the total amount, when 2 or more types of alcohol is contained.

<(C) Alkanolamine>
Preferred examples of (a) alkanolamine used in the polishing composition of the present invention include monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, ethyleneamine, and ethylenediamine. However, it is not limited to this.
One kind of these alkanolamines may be contained in the polishing liquid, or two or more kinds may be mixed and used as a mixture.
Monoethanolamine, diethanolamine, ethyleneamine, ethylenediamine, and the like can be preferably used from the viewpoint of a good balance between the effect of promoting the opening of the polyimide imide ring and the removability of the film opened by CMP.
The amount of alkanolamine used in the polishing liquid is preferably in the range of 0.1 to 60% by mass, more preferably in the range of 1 to 50% by mass, and in the range of 2 to 40% by mass. More preferably it is used. Moreover, the said usage-amount represents the total amount, when 2 or more types of alkanolamine is contained.

<(D) Alkaline compound>
In order to ring-open the polyimide constituting the polyimide film, it is preferable to use a high alkali condition, and in order to achieve the preferred pH of the present invention, the polishing liquid of the present invention contains an alkaline compound.
Examples of the alkaline compound include ammonium hydroxide; organic alkaline compounds such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and carbonates. , Phosphate, borate, tetraborate, hydroxybenzoate, glycyl salt, N, N-dimethylglycine salt, leucine salt, norleucine salt, guanine salt, 3,4-dihydroxyphenylalanine salt, alanine salt, Amino butyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydroxyaminomethane salt, lysine salt, and the like can be used.

Specific examples of the alkaline compound that can be used in the polishing liquid in the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, and triphosphate. Potassium, disodium phosphate, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate, potassium tetraborate, sodium o-hydroxybenzoate, potassium o-hydroxybenzoate, 5-sulfo-2- Examples include sodium hydroxybenzoate, potassium 5-sulfo-2-hydroxybenzoate, ammonium hydroxide, tetramethylammonium hydroxide, and tetraethylammonium hydroxide, but are not limited thereto.
Among these, sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetetramethylammonium hydroxide, sodium tetraborate, potassium tetraborate, etc. are preferably used, more preferably potassium hydroxide, ammonium hydroxide. , Tetramethylammonium hydroxide, tetraethylammonium hydroxide and the like.
These alkaline compounds may be used alone or in combination of two or more.
As the usage-amount of an alkaline compound, it can be used in 0.01-80 mass%, It is preferable to use in the range of 0.05-70 mass%, In the range of 0.1-65 mass% More preferably it is used. What is necessary is just to adjust and add so that polishing liquid may become predetermined | prescribed pH as shown in the preferable range of this content.

<PH>
In the polishing liquid of the present invention, a part of the polyimide resin constituting the polyimide film causes a ring-opening reaction under alkaline conditions, thereby improving the polishing speed of the polyimide film. More specifically, the pH is 8 or more.
The PH of the polishing liquid of the present invention is preferably 8.5 or more, and may be further highly alkaline conditions of pH 10 or more, or pH 13 or more.
What is necessary is just to adjust pH of polishing liquid to predetermined | prescribed alkalinity by adding the said (d) alkaline compound to polishing liquid suitably.

<(E) Metal anticorrosive>
It is also possible to add a metal anticorrosive (hereinafter, simply referred to as “anticorrosive” as appropriate) to the polyimide film polishing liquid of the present invention.
In the semiconductor packaging process, the substrate may be polished until the copper wiring portion adjacent to the polyimide film is exposed. In such a case, an anticorrosive agent corresponding to the metal can be added.
As the anticorrosive agent that can be used in the present invention, a compound that forms a passive film on the surface of the metal to be polished is selected, and specific examples include a heteroaromatic ring compound.

  Here, the “heteroaromatic ring compound” is a compound having a heterocycle containing one or more heteroatoms. A hetero atom means an atom other than a carbon atom and a hydrogen atom. A heterocycle means a cyclic compound having at least one heteroatom. A heteroatom means only those atoms that form part of a heterocyclic ring system.

  A hetero atom is preferably a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom, and more preferably a nitrogen atom, a sulfur atom, an oxygen atom, and a selenium atom. And particularly preferably a nitrogen atom, a sulfur atom and an oxygen atom, and most preferably a nitrogen atom and a sulfur atom.

First, the heteroaromatic ring that is the mother nucleus is described.
The number of members of the heterocyclic ring of the heteroaromatic ring compound that can be used in the present invention is not particularly limited, and it may be a monocyclic compound or a polycyclic compound having a condensed ring. The number of members in the case of a single ring is preferably 3 to 8, more preferably 5 to 7, and particularly preferably 5 and 6. The number of rings in the case of having a condensed ring is preferably 2 to 4, more preferably 2 or 3.

Specific examples of these heteroaromatic rings include the following. However, it is not limited to these.
For example, pyrrole ring, thiophene ring, furan ring, pyran ring, thiopyran ring, imidazole ring, pyrazole ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, pyrrolidine Ring, pyrazolidine ring, imidazolidine ring, isoxazolidine ring, isothiazolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, chroman ring, thiochroman ring, isochroman ring, isothiochroman ring, indoline ring, isoindoline ring , Pyridine, indolizine, indole, indazole, purine, quinolidine, isoquinoline, quinoline, naphthyridine, phthalazine, quinoxaline, quinazoline, cinnoline, pteridine, Lysine ring, perimidine ring, phenanthroline ring, carbazole ring, carboline ring, phenazine ring, antilysine ring, thiadiazole ring, oxadiazole ring, triazine ring, triazole ring, tetrazole ring, benzimidazole ring, benzoxazole ring, benzothiazole ring Benzothiadiazole ring, benzofuroxan ring, naphthimidazole ring, benzotriazole ring, tetraazaindene ring and the like, more preferably triazole ring and tetrazole ring.

Next, substituents that the heteroaromatic ring may have will be described.
In the present invention, when a specific moiety is referred to as a “group”, the moiety may be unsubstituted or substituted with one or more (up to the maximum possible) substituents. Means good. For example, “alkyl group” means a substituted or unsubstituted alkyl group.

Examples of the substituent that the heteroaromatic ring compound may have include the following. However, it is not limited to these.
For example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched or cyclic alkyl group, and even a polycyclic alkyl group such as a bicycloalkyl group is active. A methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (regardless of the position of substitution), an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group ( Examples of the carbamoyl group having a substituent include an N-hydroxycarbamoyl group, an N-acylcarbamoyl group, an N-sulfonylcarbamoyl group, an N-carbamoylcarbamoyl group, a thiocarbamoyl group, and an N-sulfamoylcarbamoyl group), a carbazoyl group. , Carboxyl group or salt thereof, oxalyl group, oxy Moyl group, cyano group, carbonimidoyl group, formyl group, hydroxy group, alkoxy group (including groups containing repeating ethyleneoxy or propyleneoxy group units), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy Or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamido group, ureido group, thioureido group, N-hydroxyureido group, Imido group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfur Nylureido group, N-acylureido group, N-acylsulfamoylamino group, hydroxyamino group, nitro group, heterocyclic group containing a quaternized nitrogen atom (for example, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group ), Isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group , A sulfo group or a salt thereof, a sulfamoyl group (the sulfamoyl group having a substituent is, for example, an N-acylsulfamoyl group or an N-sulfonylsulfamoyl group) or a salt thereof, a phosphino group, a phosphinyl group, a phosphinyloxy Group, phosphinylamino group, silyl group, etc. It is.

  Here, “active methine group” means a methine group substituted with two electron-attracting groups. “Electron withdrawing group” means, for example, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, trifluoromethyl group, cyano group, nitro group, carvone An imidoyl group is meant. Two electron-withdrawing groups may be bonded to each other to form a cyclic structure. The “salt” means a cation such as alkali metal, alkaline earth metal or heavy metal, or an organic cation such as ammonium ion or phosphonium ion.

Among these, preferable substituents in the heteroaromatic ring compound include, for example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched or cyclic alkyl group, and bicycloalkyl). A group such as a polycyclic alkyl group or an active methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (regarding the position of substitution), an acyl group, an alkoxycarbonyl group, Aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, A carbazoyl group, an oxalyl group, an oxamoyl group, Ano group, carbonimidoyl group, formyl group, hydroxy group, alkoxy group (including groups containing repeating ethyleneoxy group or propyleneoxy group units), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) ) Carbonyloxy group, carbamoyloxy group, sulfonyloxy group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (alkoxy or Aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N- Silureido group, N-acylsulfamoylamino group, hydroxyamino group, nitro group, quaternized heterocyclic group containing nitrogen atom (for example, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group Group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof Sulfamoyl group, N-acylsulfamoyl group, N-sulfonylsulfamoyl group or a salt thereof, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl group and the like.
Here, the active methine group means a methine group substituted with two electron-withdrawing groups, and the electron-withdrawing group here means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl group. Examples thereof include a sulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, and a carbonimidoyl group.

  More preferably, for example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched or cyclic alkyl group, and a polycyclic alkyl group such as a bicycloalkyl group) And may contain an active methine group), an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group (regarding the position of substitution).

  In addition, two of the above-described substituents can be combined to form a ring (aromatic or non-aromatic hydrocarbon ring or heteroaromatic ring), and these can be further combined to form a polycyclic fused ring. Benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, Pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenant Lysine ring, acridine ring, phena Tororin ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, phenazine ring, also form mentioned are) is.

Specific examples of the heteroaromatic ring compound include, but are not limited to, the following.
For example, 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1H-tetrazol-5-acetic acid, 1H- Tetrazole-5-succinic acid, 1,2,3-triazole, 4-amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 4-carboxy-1H-1,2, , 3-triazole, 4,5-dicarboxy-1H-1,2,3-triazole, 1H-1,2,3-triazole-4-acetic acid, 4-carboxy-5-carboxymethyl-1H-1,2 , 3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-carboxy-1,2,4-triazole 3,5- Carboxy-1,2,4-triazole, 1,2,4-triazole-3-acetic acid, 1H-benzotriazole, a 1H- benzotriazole-5-carboxylic acid.
These anticorrosive agents can be used alone or in combination of two or more.

  The content of the heteroaromatic ring compound in the polishing liquid of the present invention is, as a total amount, 0.0001 in 1 L of a polishing liquid used for polishing (that is, a diluted polishing liquid when diluted with water or an aqueous solution). The range of -1.0 mol is preferable, More preferably, it is the range of 0.0005-0.5 mol, More preferably, it is the range of 0.0005-0.05 mol.

<(F) Oxidizing agent>
An oxidizing agent can be added to the polishing liquid of the present invention for the purpose of improving the etching rate of the polyimide film.
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 the iron (III) salt include inorganic iron (III) salts such as iron (III) nitrate, iron (III) chloride, iron (III) sulfate, iron (III) bromide, and iron (III). Organic complex salts are preferably used.

  Among these oxidizing agents, hydrogen peroxide, iodate, hypochlorite, and persulfate are preferably used, and hydrogen peroxide, hypochlorite, and persulfate are more preferably used. It is done.

  The amount of the oxidizing agent used can be in the range of 0.0001 to 10 mol, preferably 0.001 to 8 mol, more preferably in the range of 0.001 to 6 mol, per liter of the polishing liquid at the time of use. It is preferable to use in.

<Other additives>
In addition to the essential components and preferred additives, various known additives can be added to the polishing liquid of the present invention depending on the purpose within a range not impairing the effects of the present invention.
(Surfactant)
A surfactant can be added to the polishing liquid of the present invention.
In semiconductor devices, there is a metal film layer such as copper wiring adjacent to the polyimide film, but when the metal part is exposed during polishing of the polyimide film, the surfactant is adsorbed on the metal film to protect the exposed surface, It is thought that it fulfills the function of suppressing the polishing of the metal film.
Surfactants that can be used in the present invention are those selected from the group of anionic (anionic), cationic (cationic), nonionic (nonionic), and amphoteric (betaine) surfactants. Is preferred.

Examples of the anionic surfactant include carboxylic acid, sulfonic acid, sulfate ester, phosphate ester and salts thereof.
Carboxylic acids and salts thereof include fatty acid salts (for example, beef tallow fatty acid soda, sodium stearate, potassium oleate, castor oil potash), N-acyl amino acid salts (for example, palm oil fatty acid sarcosine triethanolamine), polyoxyethylene or Examples include polyoxypropylene alkyl ether carboxylate and acylated peptide.
Examples of sulfonic acids and salts thereof include alkyl sulfonates (for example, dioctyl sulfosuccinate ester salts), alkyl benzene sulfonic acids (for example, dodecyl benzene sulfonic acid (soft), (hard), ammonium dodecyl benzene sulfonate (soft), (hard ), Dodecylbenzenesulfonic acid triethanolamine), alkyl diphenyl ether disulfonates (eg sodium alkyldiphenyl ether disulfonate), alkyl naphthalene sulfonates (eg monoisopropyl naphthalene sulfonic acid, diisopropyl naphthalene sulfonic acid, triisopropyl naphthalene sulfonic acid) Ammonium), alkylsulfosuccinates (eg sodium dialkylsulfosuccinate, polyoxyethylene lauryl ether) Rufosuccinic acid disodium), α-olefin sulfonate, N-acyl sulfonate (for example, coconut oil fatty acid methyl taurine sodium, polyoxyethylene coconut oil aliphatic monoethanolamide sodium sulfate), naphthalene and other aromatic sulfonic acids Formalin condensates (for example, sodium salt of β-naphthalenesulfonic acid formalin condensate, sodium salt of special aromatic sulfonic acid formalin condensate) and the like.

Sulfated ester salts such as sulfated oils, alkyl sulfates (for example, sodium lauryl sulfate, higher alcohol sodium sulfate, triethanolamine lauryl sulfate, ammonium lauryl sulfate), alkyl ether sulfates (for example, polyoxyethylene or polyoxypropylene alkyl ether) Examples thereof include sulfates (for example, sodium polyoxyethylene lauryl sulfate, polyoxyethylene lauryl ether sulfate triethanolamine), alkylamide sulfates, and the like.
As phosphate ester salts, alkyl phosphates (for example, potassium octyl phosphate, potassium lauryl phosphate, potassium octyl ether phosphate), polyoxyethylene or polyoxypropylene alkylallyl ether phosphates (for example, polyoxyethylene alkylphenyl ether phosphorus) Acid).

Nonionic surfactants include ether type, ether ester type, ester type, and nitrogen-containing type.
Ether types include polyoxyalkylene alkyl and polyoxyalkylene alkyl phenyl ethers (for example, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, Oxyethylene mysterite ether, polyoxyethylene octyldodecyl ether), polyoxyethylene derivatives (eg, polyoxyethylene disulfonated phenyl ether), polyoxyethylene polyoxypropylene glycol, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene Polyoxypropylene block polymer, polyoxyethylene polyoxypropylene Ruki ether, and the like.
As ether ester type, polyoxyethylene ether of glycerin ester, polyoxyethylene fatty acid ester (for example, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyoxyethylene hydrogenated castor oil), polyoxyethylene Sorbitan fatty acid esters (for example, polyoxyethylene sorbitan monococonut oil fatty acid ester, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxy Ethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbate Emissions triisostearate, polyoxyethylene sorbitan mono coconut fatty acid ester, polyoxyethylene sorbit tetraoleate), include polyoxyethylene ethers of sorbitol esters.

As ester types, sorbitan fatty acid esters (for example, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate), glycerin fatty acid esters (for example Glycerol monostearate, glycerol monooleate), polyglycerol ester, sorbitan ester, propylene glycol ester, sucrose ester and the like.
Examples of the nitrogen-containing type include fatty acid alkanolamide (for example, coconut fatty acid diethanolamide), polyoxyethylene alkylamine (for example, polyoxyethylene laurylamine), polyoxyethylene alkylamide (for example, polyoxyethylene lauric acid amide), and the like. It is done.
In addition, fluorine-based surfactants, acetylene-containing nonionic surfactants (for example, diisobutyldimethylbutenediol polyoxyethylene glycol ether) and the like can also be used.

  As cationic surfactants, alkylamine salts (for example, coconut amine acetate, stearylamine acetate), quaternary ammonium salts (for example, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyldimethylammonium) Chloride, alkylbenzyldimethylammonium chloride), alkylpyridinium salts (for example, cetylpyridinium chloride), and the like.

  As amphoteric surfactants, alkylbetaine type (for example, lauric betaine (lauryldimethylaminoacetic acid betaine, stearylbetaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine), amine oxide type (for example, lauryldimethyl) Amine oxide).

Of the surfactants, anionic surfactants and nonionic surfactants are preferably used. Among the anionic surfactants, a surfactant having a sulfo group is more preferable, and a surfactant having both a phenyl group and a sulfo group is more preferable. Specifically, for example, alkylbenzene sulfonic acid, alkyl diphenyl ether disulfonic acid, and salts thereof, and alkyl diphenyl ether disulfonic acid is particularly preferable.
As the nonionic surfactant, an ether type, an ether ester type, or an ester type is preferably used.

  Examples of the salt include ammonium salts (for example, salts with ammonia and triethanolamine), alkali metal salts (for example, lithium salts, sodium salts, potassium salts), halogens, and the like.

  The addition amount of the surfactant is preferably 0.0001 to 10 g, more preferably 0.0005 to 5 g, and more preferably 0.0005 to 3 g in 1 L of a polishing liquid used for polishing as a total amount. It is particularly preferable that

  When a surfactant is used in combination, a surfactant with a different charge is not used because of aggregation in the polishing liquid. The combinations that can be used are (1) only anionic surfactant, (2) only cationic surfactant, (3) only nonionic surfactant, (4) only betaine surfactant, (5) anionic surfactant and nonionic Surfactant, (6) cationic surfactant and nonionic surfactant, (1), (2), (3), (5), (6) are preferred in these combinations, (1), The combination of (3) and (5) is more preferable.

(Chelating agent)
The polishing liquid of the present invention can contain a chelating agent (that is, a hard water softening agent) as necessary in order to reduce adverse effects such as mixed multivalent metal ions.
Chelating agents include general water softeners and related compounds that are calcium and magnesium precipitation inhibitors, such as nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid. , Ethylenediamine-N, N, N ′, N′-tetramethylenesulfonic acid, transcyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid ( SS form), N- (2-carboxylateethyl) -L-aspartic acid, β-alanine diacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N , N′-bis (2-hydroxyben Le) ethylenediamine -N, N'-diacetic acid, 1,2-dihydroxy-4,6-disulfonic acid.

Two or more chelating agents 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 so that it is in the range.

<Chemical mechanical polishing method>
As described above, the polishing liquid of the present invention contains (a) abrasive grains, (b) alcohols, (c) alkanolamine, and (d) an alkaline compound, and (d) addition of the alkaline compound. To adjust the pH to 8 or more.
By using the polishing liquid of the present invention, alcohols and alkanolamines act under alkaline conditions to open the polyimide imide ring constituting the polyimide film, which is easy to remove. The portion is physically removed by the pad and abrasive grains with a CMP apparatus. The polishing solution also acts on the newly exposed polyimide film surface where the ring-opened region is physically removed, and the polyimide film surface is repeatedly opened and the physical removal of the portion is repeated. The film is polished. Since the polyimide film is polished in a state where the imide ring has been opened, it does not need to be eluted out of the system unlike the conventional etching method. It is estimated that the film to be removed is polished and removed. For this reason, high-speed polishing is possible, and even under high-speed polishing conditions, the polyimide film substrate is polished by rotating the surface plate by CMP, so that there is no concern about over-polishing in local areas such as etching, and flatness It is believed that a high polished surface can be obtained.

In the chemical mechanical polishing method of the present invention, the polishing liquid for polyimide film of the present invention is supplied to a polishing pad on a polishing platen, and the polishing pad is rotated by rotating the polishing platen. Polishing is performed by making a relative movement while making contact with the surface to be polished.
Hereinafter, this chemical mechanical polishing method will be described in detail.

(Polishing equipment)
First, an apparatus capable of carrying out the polishing method of the present invention will be described.
As a polishing apparatus applicable to the present invention, a holder for holding an object to be polished (semiconductor substrate or the like) having a surface to be polished and a polishing pad are attached (a motor or the like whose rotation speed can be changed is attached). A general polishing apparatus provided with a polishing surface plate can be used. For example, FREX300 (Ebara Seisakusho) can be used.

(Polishing pressure)
In the polishing method of the present invention, polishing is preferably performed at a polishing pressure, that is, a contact pressure between the surface to be polished and the polishing pad of 3000 to 25000 Pa, and more preferably 6500 to 14000 Pa.

(Number of rotations of polishing surface plate)
In the polishing method of the present invention, the polishing is preferably performed at a rotation speed of the polishing platen of 50 to 200 rpm, more preferably 60 to 150 rpm.

(Polishing liquid supply method)
In the present invention, while polishing a target polyimide film, a polishing liquid for polyimide film is continuously supplied to a polishing pad on a 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. Thereby, a polishing liquid spreads uniformly on the surface to be polished, and high flatness after polishing can be realized.
From such a viewpoint, the supply amount of the polishing liquid on the polishing platen in the polishing method of the present invention is preferably 50 to 500 ml / min, and more preferably 100 to 300 ml / min.

  In the polishing method of the present invention, water or an aqueous solution can be added to a concentrated polishing liquid for dilution. As a dilution method, for example, a method of supplying a concentrated polishing liquid to a polishing pad by joining and mixing a pipe for supplying a concentrated polishing liquid and a pipe for supplying water or an aqueous solution together in the middle. Can be mentioned. 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. Conventional methods such as a method of providing blades that rotate 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 polishing pad and the surface to be polished are provided. A method of mixing by relative motion can also be used in the present invention.
Further, a method in which a predetermined amount of concentrated polishing liquid and water or an aqueous solution are mixed in one container, mixed and diluted to a predetermined concentration, and then the mixed liquid is supplied to the polishing pad is also applicable to the present invention. be able to.

  In addition to these methods, a 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 and diluted to be supplied to the polishing pad is also used in the present invention. be able to. When an oxidizing agent is used, it may be preferable to divide into two components from the viewpoint of storage stability of the polishing liquid. In this case, a method of adding the oxidizing agent separately to other components can be used. .

  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 diluted water may be separately supplied to the polishing surface.

(Polishing pad)
The polishing pad used in the polishing method of the present invention is not particularly limited, and may be a non-foamed structure pad or a foamed structure 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.

  The polishing pad in the present invention may further contain abrasive grains (for example, ceria, silica, alumina, resin, etc.) used for polishing. In addition, each has a softness and a hardness, and either of them 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. Further, the surface that contacts the polished surface may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

<Polishing target>
The object to be polished by the polishing method of the present invention is a barrier metal film formed on the entire surface of an interlayer insulating film having a recess, and copper or copper formed so that the recess is buried in the surface of the barrier metal film. And a conductive film made of an alloy, wherein at least one of the substrate surface and the interlayer insulating film has a polyimide film. The substrate to be polished is a semiconductor substrate, preferably an LSI having wiring made of copper metal and / or copper alloy, and particularly preferably wiring is a copper alloy.
As a workpiece to be polished, a conductive material film is formed on a wafer in which a conductive material film is formed on a support substrate and an interlayer insulating film provided on a wiring formed on the support substrate. As long as the laminated body has a polyimide film on the surface to be polished, materials at all stages that require planarization in the semiconductor device manufacturing process can be exemplified.

  Hereinafter, the present invention will be described by way of examples. The present invention is not limited to these examples.

(Polished object)
An object to be polished (substrate, wafer) to be polished in the polishing method of the present invention will be described.
In the present invention, a thermosetting polyimide resin was applied to a 300 mm silicon substrate with a spin coater and heated at 200 ° C. for 1 hour to prepare a substrate on which the polyimide film was cured. The film thickness of the polyimide film after thermosetting was 20 μm. This is referred to as a substrate 1.
Further, for the purpose of confirming the influence on the adjacent metal wiring part, a sample was prepared by polishing a SEMATECH754 wafer (manufactured by SEMATECH) by the method of Example 1 of Japanese Patent Application Laid-Open No. 2004-279491. This is referred to as a substrate 2.

[Examples 1 to 10, Comparative Examples 1 to 5]
Polishing liquids 101 to 110 of Examples 1 to 10 shown in Table 1 below and polishing liquids 201 to 205 of Comparative Examples 1 to 5 were prepared, and polishing tests and evaluations were performed.
(Preparation of polishing liquid)
The following compositions were mixed to prepare each polishing liquid.
・ (A) Abrasive grains [Abrasive grains shown in Table 1] ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 100g / L
(B) Alcohols [compounds shown in Table 1] ... 180 g / L
(C) Alkanolamine [compound shown in Table 1] ... 90 g / L
(D) Alkaline compounds [compounds shown in Table 1] ... 300 g / L
(E) Anticorrosive agent [compound shown in Table 1] ... 0.01 g / L
(F) Oxidizing agent [compound shown in Table 1] ... 10 g / L
Pure water was added to bring the total volume to 1000 ml, and the pH was adjusted as shown in Table 1 to obtain a polishing liquid. In addition, KOH was used for pH adjustment.

(Polishing test)
Polishing was performed under the following conditions, and the polishing rate and dishing were evaluated.
・ Polishing equipment: FREX300 (Ebara Works)
-Object to be polished (wafer): substrate 1 described above
Polishing pad: IC1400-K Groove (Rodel)
(Polishing conditions)
Polishing pressure (contact pressure between the surface to be polished and the polishing pad): 10.5 kPa
Polishing liquid supply rate: 200 ml / min
Polishing platen rotation speed: 104rpm
Polishing head rotation speed: 105 rpm (Processing linear velocity: 1.0 m / sec)

(Evaluation methods)
1. Polishing rate Calculation of polishing rate: The polyimide film-coated wafer of (1) was polished for 60 seconds, and the polishing rate was calculated from the weight change before and after polishing.
Polishing rate (nm / min) = (Polyimide film thickness before polishing−Polyimide film thickness after polishing) / Polishing time [1 minute]
2. Flatness After polishing the polyimide film using the substrate 1 as an object to be polished, the polished surface was washed with pure water and dried. The dried polished surface was observed and evaluated by AFM, and the flatness was evaluated based on the following evaluation criteria. The obtained results are shown in Table 1.
-Evaluation criteria-
○: Flatness with no practical problems ×: Observation of irregularities in the wafer surface

3. Scratch Evaluation After polishing the polyimide film using the substrate 1 as an object to be polished, the polished surface was washed with pure water and dried. The dried polished surface was observed with an optical microscope and Surfscan SP-1 manufactured by KLA Tencor, and scratches were evaluated based on the following evaluation criteria. The obtained results are shown in Table 1.
-Evaluation criteria-
Yes: No problem scratches observed No: Many problem scratches observed on wafer surface

  As is apparent from Table 1, it was confirmed that when the polishing liquid of the present invention was used, a high polishing rate could be obtained without causing polishing flaws and the flatness after polishing was excellent. On the other hand, in Comparative Example 1 containing no abrasive grains, a sufficient polishing rate could not be obtained, and the polishing unevenness was large, so that scratch could not be confirmed.

4). Evaluation of corrosiveness to copper wiring The polishing liquid 1011 of Example 1 and the polishing liquid 110 of Example 10 were prepared by removing polishing grains 1011 and 1012 respectively, and the substrate 2 having an exposed surface of the copper wiring was prepared. The wafer was immersed for 3 minutes at 25 ° C., and the degree of corrosion of the Cu wiring part was observed with an SEM.
As a result, no corrosion of the copper surface was confirmed in the polishing liquid 1011 (corresponding to Example 1) prepared with PH 12.5. On the other hand, slight corrosion was confirmed in the polishing liquid 1012 (corresponding to Example 10) prepared with PH 13.8. Polishing liquid 1013 obtained by adding 0.002 g / L benzotriazole to this polishing liquid 1012 was newly prepared (PH was 13.8), and the same evaluation was performed. As a result, no corrosion of Cu was observed.
According to this evaluation and the comparison between Example 1 and Example 10, when the pH of the polishing liquid is 13 or more, the polishing rate is improved, but there is a concern about corrosion of the copper wiring. By adding a metal anticorrosive, It was confirmed that the corrosion of the copper wiring can be suppressed without lowering the pH.

[Example 11]
A polishing liquid 111 was newly prepared in the same manner as in Example 10 except that 0.002 g / L of benzotriazole was added to the polishing liquid 110 of Example 10. The pH was 13.8. This polishing liquid 111 was evaluated in the same manner as in Example 1. The results are shown in Table 1. When the polishing rate was evaluated, it was 7700 nm / min, which was a little lower than that of Example 10, but it was found that a much higher polyimide removal rate was obtained compared to the polishing solution 201 having only the etching function so far. Moreover, it turns out that the outstanding grinding | polishing performance is expressed, suppressing the corrosion of copper by addition of a metal anticorrosive.

Claims (8)

In semiconductor device manufacturing, a polishing liquid mainly used for chemical mechanical polishing of polyimide film,
A polishing liquid containing (a) abrasive grains, (b) alcohols, (c) alkanolamine, and (d) an alkaline compound, and having a pH of 8 or more.   The polishing liquid according to claim 1, further comprising (e) a metal anticorrosive.   3. The polishing liquid according to claim 1, further comprising (f) an oxidizing agent.   The polishing liquid according to any one of claims 1 to 3, wherein the alcohol (b) is a lower alcohol.   The polishing liquid according to claim 1, wherein the alcohol (b) is glycol.   The polishing liquid according to claim 5, wherein the glycol is selected from ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, polyethylene glycol, and a mixture thereof.   2. The (c) alkanolamine is selected from monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, ethyleneamine and a mixture thereof. The polishing liquid according to claim 6.   In semiconductor device manufacture, the polyimide film is mainly chemically and mechanically polished using the polishing liquid according to any one of claims 1 to 7.