JP2010080842A - Polishing composition and polishing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing composition capable of maintaining a polyimide film with a high planarity in a short time and capable of polishing the polyimide film by a chemical-mechanical polishing by suppressing the occurrence of a polishing hurt, and to provide a polishing method using the polishing composition. <P>SOLUTION: The polishing composition is used for the chemical-mechanical polishing of the polyimide film, containing: (A) abrasive grain; (B) water; and (C) at least one organic solvent chosen from groups of (C1) non-protonic organic solvent having a compatibility with the water, and (C2) protonic organic solvent having a compatibility with the water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing composition useful for performing chemical mechanical planarization of a polyimide film, and a polishing method using the same. In particular, the present invention 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 a semiconductor device typified by a semiconductor integrated circuit (hereinafter sometimes referred to as “LSI”), chemical mechanical polishing (Chemical Mechanical Polishing) is used as a planarization technique performed in each process of semiconductor device manufacturing. Polishing, hereinafter may be referred to as “CMP”). For example, CMP is used to polish an interlayer insulating film (such as SiO ₂ ) or a metal thin film used for wiring, smooth the substrate, or remove excess metal thin film during wiring formation (for example, , See Patent Document 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 platen and the substrate are rotated with a predetermined pressure (polishing pressure) applied from the back surface.
In CMP, the surface of a substrate is flattened by mechanical friction generated by the above operation.

Polyimide is excellent in thermal stability, chemical stability, electrical characteristics, mechanical characteristics, and the like. For this reason, polyimide is used for a wide variety of applications such as an insulating material for a wiring board. For example, a polyimide film or a film containing polyimide as a main component (hereinafter sometimes simply referred to as “polyimide film”) is also applied to a semiconductor package as described in Non-Patent Document 1 below.
However, organic polymer resin substrates such as polyimide are difficult to remove or planarize by etching or the like.

Regarding the etching of the polyimide film, for example, a method of wet etching using a solution containing hydrazine as a main component (see Patent Documents 2 and 3), an etching method using potassium hydroxide (see Patent Document 4), and during etching A method of irradiating laser, infrared rays, and microwaves (see Patent Documents 5 to 7) is disclosed.
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. Furthermore, the use of a solution containing a compound such as hydrazine is problematic from the viewpoint of safety.

In addition, as another method, a method is also disclosed in which a polishing liquid to which an abrasive such as alumina is added, the polishing liquid is spray-added, discharged onto the surface of the polyimide film at a high pressure, and etched (for example, (See Patent Documents 8 and 9).
However, even when a polyimide film is etched by such a method of mixing an abrasive and discharging a polishing composition, etching may vary depending on the discharge angle, which may impair flatness and scratches. there were.

Further, in the case of a substrate having a polyimide film, as described above, there is a problem of throughput in wet etching, and polishing unevenness may occur in spray addition of the polishing composition, and flatness and There is a problem with the roughness of the film surface, and it has been difficult to achieve satisfactory flattening without causing a problem of polishing scratches by any means.
JP 2006-049790 A JP-A-3-101228, JP-A-5-202206 JP-A-5-301981 JP 2002-20513 A JP 2002-53684 A JP 2002-128922 A JP 2002-307111 A, JP 2003-8171 A Electronic Components and Technology Conference, 2006. Proceedings. (56th Publicant Date: 30 May-2 June 2006)

This invention is made | formed in view of the said situation, and makes it a subject to achieve the following objective.
That is, the present invention provides a polishing composition capable of polishing a polyimide film by chemical mechanical polishing while maintaining high flatness in a short time and suppressing generation of polishing flaws, and the polishing composition. An object of the present invention is to provide a polishing method using this.

As a result of intensive studies, the present invention has found that the above-mentioned problems can be solved by the following polishing composition and a polishing method using the same, and the present invention has been completed.
The polishing composition of the present invention and the polishing method using the same are as follows.

<1> Used for chemical mechanical polishing of polyimide film, (A) abrasive grains, (B) water, (C) (C1) water-compatible aprotic organic solvent and (C2) water And at least one organic solvent selected from the group of protic organic solvents having compatibility with the polishing composition.
<2> The polishing composition according to <1>, wherein the (A) abrasive grain is at least one selected from alumina and silica.

<3> The polishing according to <1> or <2>, wherein the (C1) water-compatible aprotic organic solvent is one selected from methyl ethyl ketone, tetrahydrofuran, dioxane, and N-methylpyrrolidone. Composition.
<4> The polishing composition according to <1> or <2>, wherein the (C2) water-compatible protic organic solvent is one selected from methanol, ethanol, and ethylene glycol.

<5> The polishing composition according to any one of <1> to <4>, further comprising (D) a metal anticorrosive.
<6> The polishing composition according to any one of <1> to <5>, further comprising (E) an oxidizing agent.

<7> The oxidizing agent (E) is hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, The polishing composition according to <6>, selected from the group consisting of persulfate, dichromate, permanganate, ozone water, silver (II), and iron (III) salt.
<8> A polishing method for chemically and mechanically polishing an object to be polished including a polyimide film using the polishing composition according to any one of <1> to <7> in a semiconductor device manufacturing process. .

The polishing composition of the present invention is used for chemical mechanical polishing of a polyimide film, and is an aprotic organic compound that is compatible with (A) abrasive grains, (B) water, and (C) (C1) water. And (C2) at least one organic solvent selected from the group of protic organic solvents having compatibility with water.
Although the action of the present invention is not clear, the polishing composition of the present invention is (C) the film quality of the surface of the polyimide film is changed by a specific organic solvent, and (A) the physical polishing effect by the abrasive grains is maximized. The polyimide film, which is the surface to be polished, is instantly polished by using a combination of abrasive grains and a CMP apparatus without requiring a long time as in conventional etching, thereby enabling high-speed polishing. I believe that.
Furthermore, since the object to be polished having a polyimide film is also polished by rotating the surface plate with a CMP apparatus, it is considered that local overpolishing such as etching hardly occurs and a highly flat polished surface can be obtained. It is done.

According to the present invention, it is possible to provide a polishing composition capable of polishing a polyimide film by chemical mechanical polishing while maintaining high flatness in a short time and suppressing generation of polishing flaws.
Moreover, the polishing composition of the present invention can provide a polishing method capable of polishing a polyimide film in a short time while suppressing the generation of polishing flaws and achieving high flatness.

Hereinafter, specific embodiments of the present invention will be described in detail.
[Polishing composition]
The polishing composition of the present invention is used for chemical mechanical polishing of a polyimide film, and is an aprotic organic compound that is compatible with (A) abrasive grains, (B) water, and (C) (C1) water. A polishing composition comprising: a solvent; and (C2) at least one organic solvent selected from the group of protic organic solvents compatible with water (hereinafter sometimes referred to as “specific organic solvent”). .
The polishing composition of the present invention may contain an optional component, if necessary, in addition to (A) abrasive grains, (B) water, and (C) a specific organic solvent. Examples of the optional component include (D) a metal anticorrosive, (E) an oxidizing agent, a pH adjuster, and a surfactant.
Hereinafter, each component in the polishing composition of the present invention will be described in detail.

<Polyimide film>
First, a description will be given of a polyimide film to be polished by the polishing composition of the present invention.
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 the substrate surface on which wiring can be formed, and may be a film formed by applying a resin liquid on a wafer or the like, A film formed by laminating a polyimide film formed in advance on a wafer or the like, or a film formed by adhering a polyimide film formed in advance by an epoxy adhesive or the like to the substrate surface may be used.
Specific examples of the polyimide film include, but are not limited to, the polyimide described in Non-Patent Document 1 and the polyimide film described in JP-A-2002-20513.

<(A) Abrasive grain>
The polishing composition of the present invention contains (A) abrasive grains. Preferable abrasive grains include, for example, silica (for example, precipitated silica, fumed silica, colloidal silica, synthetic silica), ceria, alumina, titania, zirconia, germania, manganese oxide, diamond and the like, silica, alumina, oxidation Inorganic abrasive grains such as manganese are preferably used, and among these, alumina and silica are more preferable.

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 nm to 1000 nm, more preferably 10 nm to 800 nm. In order to achieve a sufficient polishing speed, particles of 20 nm or more are preferable. For the purpose of not generating excessive frictional heat during polishing, the particle size is preferably 700 nm or less.
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.

  Moreover, as an abrasive grain in this invention, it is also possible to use an organic polymer particle together with the above-mentioned inorganic abrasive grain. When inorganic abrasive grains and organic polymer particles are used in combination as abrasive grains, the content ratio can be appropriately set according to the purpose. Further, as abrasive grains, colloidal silica surface-modified with aluminate ions or borate ions, colloidal silica with controlled surface potential, such as colloidal silica subjected to various surface treatments, or composite abrasives composed of a plurality of materials It is also possible to use grains according to the purpose.

Although the addition amount of the abrasive grains in the polishing composition of the present invention is appropriately selected according to the purpose, it is generally used in the range of 0.01 to 80% by mass with respect to the total mass of the polishing composition. be able to. In the present invention, although the polishing rate increases as the amount of abrasive grains increases, the addition amount of abrasive grains is 0.1 to 70% by mass from the viewpoint of suppressing scratches caused by the abrasive grains. Preferably, it is 0.2-60 mass%.
When a plurality of types of abrasive grains are used, the added amount represents the total amount.
The above-mentioned abrasive grains can be used in combination of two or more, and depending on the purpose, the abrasive grains of the same type and different sizes are used in combination, or different kinds of abrasive grains are mixed. It is also possible to use it.

<(B) Water>
As the (B) water that can be used in the polishing composition of the present invention, water that is generally used for semiconductor materials, such as distilled water and ion exchange water, can be used.

<At least one organic solvent selected from the group of (C) (C1) aprotic organic solvent compatible with water and (C2) protic organic solvent compatible with water>
The polishing composition of the present invention comprises (C) (C1) an aprotic organic solvent compatible with water, and (C2) at least one organic solvent selected from the group of protic organic solvents compatible with water. Contains a solvent.

Examples of (C1) an aprotic organic solvent compatible with water and (C2) a protic organic solvent compatible with water are listed below. For example, it is not limited to this.
Examples of the aprotic organic solvent having compatibility with (C1) water include ketone-based, ether-based and amide-based solvents such as acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, Acetonitrile and the like are typical. Among these, methyl ethyl ketone, tetrahydrofuran, dioxane, N-methylpyrrolidone and the like can be preferably used, and methyl ethyl ketone, dioxane and N-methylpyrrolidone are preferable.

  (C2) As the protic organic solvent having compatibility with water, alcohol, glycol, glycol ether are typical, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, ethylene glycol, Typical examples include propylene glycol and ethoxyethanol, and methanol, ethanol, ethylene glycol and the like can be preferably used, and methanol and ethanol are good.

  In the present invention, the content of the specific organic solvent (C) is, as a total amount, in 1 L of a polishing composition when used for polishing (that is, a polishing composition after dilution when diluted with water or an aqueous solution), The range of 1-900g is preferable, More preferably, it is the range of 2-800g, More preferably, it is the range of 5-700g.

As the (C) specific organic solvent of the present invention, two or more types from the group of (C1) aprotic organic solvents compatible with water may be used, or (C2) protons compatible with water. Two or more kinds from the group of volatile organic solvents may be used.
It is also possible to use (C1) an aprotic organic solvent compatible with water and (C2) a protic organic solvent compatible with water. As a ratio in that case, (C1) / (C2) is preferably in a range of 0.05 / 0.95 to 0.95 / 0.05, and 0.1 / 0.9 to 0.9. The range of /0.1 is more preferable. Within this range, the polishing rate is preferably increased.

<Metal anticorrosive>
It is preferable to add (D) a metal anticorrosive (hereinafter sometimes referred to as “anticorrosive”) to the polishing composition of the present invention.
In the semiconductor packaging process, polishing may be performed until the copper wiring portion adjacent to the polyimide film is exposed. In such a case, it is preferable to add an anticorrosive agent according to the metal.
Examples of the anticorrosive agent that can be used in the present invention include a heteroaromatic ring compound as a compound that forms a passive film on the surface of a metal to be polished.

  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, either external to the ring system, separated from the ring system by at least one non-conjugated single bond, Atoms that are part of a further substituent of are not meant.

  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 ring, indolizine ring, indole ring, indazole ring, purine ring, quinolidine ring, isoquinoline ring, quinoline ring, naphthyridine ring, phthalazine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, Lysine ring, perimidine ring, phenanthroline ring, carbazole ring, carboline ring, phenazine ring, anti-lysine 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 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 jointly form a ring (aromatic or non-aromatic hydrocarbon ring or heteroaromatic ring), which are further combined to form a polycyclic fused ring. Examples thereof include 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, phenanthridine ring Acridine ring, phenanthroline ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, phenazine ring, also form mentioned are) it is.

  Specific examples of the heteroaromatic ring compound 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, 1H-tetrazole-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-di Rubokishi-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 anticorrosive agent (D) in the polishing composition of the present invention is, as a total amount, a polishing composition when used for polishing (that is, a polishing composition after dilution when diluted with water or an aqueous solution). ) In 1 L, the range of 0.0001 to 1.0 mol is preferable, more preferably 0.0005 to 0.5 mol, and still more preferably 0.0005 to 0.05 mol.

<(E) Oxidizing agent>
It is preferable to add (E) an oxidizing agent to the polishing composition of the present invention for the purpose of improving the polishing rate of the polyimide film.
(E) By containing an oxidizing agent, the oxidizing agent acts on the surface of the polyimide film, and the polyimide film becomes easy to remove, and can be physically removed by a pad and abrasive grains with a CMP apparatus. . A new polyimide film is exposed on the polished surface, but the oxidizing agent again acts on the surface to make it easy to remove the film surface, contributing to an improvement in the polishing rate.

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 iron (III) in addition to inorganic iron (III) salts such as iron (III) nitrate, iron (III) chloride, iron (III) sulfate, and iron (III) bromide. 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. Moreover, it is also possible to use these oxidizing agents in combination of two or more kinds as required, for example, in order to make the reaction time with the polyimide film as instantaneous as possible.

  (E) The amount of the oxidizing agent used can be used in the range of 0.0001 mol to 20 mol, preferably in the range of 0.001 to 15 mol, more preferably in the range of 0.001 to 10 mol, per liter of the polishing liquid. It is preferable to use in.

<PH>
The polishing composition of the present invention can be polished in any acidic to alkaline pH range, and may be pH 1 or less or pH 14 or more exceeding the measurement limit of a pH meter, but from the point of polishing rate, it is pH 0.1 or more. Preferably, it is 1.0 or more.

  In order to adjust the pH of the polishing composition of the present invention to a desired pH, it is preferable to add a pH adjuster. Examples of the pH adjuster include alkali, acid, and pH buffer. Below, the alkali, acid, and buffer which can be used for this invention are demonstrated.

Examples of the pH adjuster for adjusting the pH of the polishing composition to the acidic side include inorganic acids and organic acids.
Examples of inorganic acids include sulfuric acid, nitric acid, boric acid, phosphoric acid and the like. Among these inorganic acids, sulfuric acid, nitric acid, and phosphoric acid are preferably used, and sulfuric acid, nitric acid, and phosphoric acid are more preferably used.
Examples of organic acids include amino acids, acetic acid, glycolic acid, diglycolic acid and the like, but are not limited to these, and any organic acid can be selected as needed.
It is also possible to use several kinds of acids in combination, or to use organic acids and inorganic acids in combination.

  Examples of the pH adjuster for adjusting the pH of the polishing composition to the alkaline side include organic ammonium hydroxide such as ammonium hydroxide and tetramethylammonium hydroxide (TMAH), sodium hydroxide, potassium hydroxide, and hydroxide. Alkali metal hydroxide such as lithium, carbonate, phosphate, borate, tetraborate, hydroxybenzoate, glycyl salt, N, N-dimethylglycine salt, leucine salt, norleucine salt, guanine salt, Examples include 3,4-dihydroxyphenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydroxyaminomethane salt, lysine salt, etc. Not as long.

In addition, it is also effective to add a pH buffering agent to the polishing composition of the present invention in order to minimize pH fluctuation during polishing.
Examples of what may act as a pH buffer include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, phosphoric acid Disodium, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, sodium o-hydroxybenzoate (sodium salicylate), potassium o-hydroxybenzoate, 5- Sodium sulfo-2-hydroxybenzoate (sodium 5-sulfosalicylate), potassium 5-sulfo-2-hydroxybenzoate (potassium 5-sulfosalicylate), ammonium hydroxide, and also glycine, alanine, N-methylglycine Amino acids and amino acid derivatives, butyric acid, Organic acids such as cholic acid may also be used as buffering agents.

As mentioned above, although the specific example of the pH adjuster was given, it cannot be overemphasized that it is not limited to the said specific example as long as the pH of polishing composition can be adjusted to a desired value.
The addition amount of the pH adjuster is not limited as long as the pH of the polishing composition can be adjusted to a desired value.

<Surfactant>
The polishing composition of the present invention can also contain a surfactant.
The surfactant in the present invention is selected from the group consisting 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 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 disulfonate (eg sodium alkyldiphenyl ether disulfonate), alkyl naphthalene sulfonate (eg monoisopropyl naphthalene sulfonic acid, diisopropyl naphthalene sulfonic acid, triisopropyl naphthalene sulfone) Acid ammonium), alkylsulfosuccinates (eg, sodium dialkylsulfosuccinate, polyoxyethylene lauryl ether) Disodium sulfosuccinate), α-olefin sulfonates, N-acyl sulfonates (for example, coconut oil fatty acid methyl taurine sodium, polyoxyethylene coconut oil aliphatic monoethanolamide sodium sulfate), naphthalene and other aromatic sulfonic acids Formalin condensate (for example, sodium salt of β-naphthalenesulfonic acid formalin condensate, sodium salt of special aromatic sulfonic acid formalin condensate).

  Examples of sulfate salts include sulfated oil, alkyl sulfates (for example, sodium lauryl sulfate, higher alcohol sodium sulfate, lauryl sulfate triethanolamine, ammonium lauryl sulfate), alkyl ether sulfates (for example, polyoxyethylene or polyoxypropylene alkyl) Ether sulfates (for example, sodium polyoxyethylene lauryl sulfate, polyoxyethylene lauryl ether sulfate triethanolamine), alkylamide sulfates; as phosphate salts, alkyl phosphates (for example, potassium octyl phosphate, potassium lauryl phosphate, Potassium octyl ether phosphate), polyoxyethylene or polyoxypropylene alkyl allyl ether phosphate (eg, polyoxyethylene alkyl phosphate) Alkenyl ether phosphate), it can be mentioned.

Examples of the nonionic surfactant include ether type, ether ester type, ester type, and nitrogen-containing type nonionic surfactants.
Ether type nonionic surfactants include polyoxyalkylene alkyl and polyoxyalkylene alkyl phenyl ethers (eg, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, Polyoxyethylene higher alcohol ether, polyoxyethylene myristol ether, polyoxyethylene octyldodecyl ether), polyoxyethylene derivatives (eg, polyoxyethylene disulfonated phenyl ether), polyoxyethylene polyoxypropylene glycol, alkylallyl formaldehyde condensation Polyoxyethylene ether, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene Polyoxypropylene alkyl ethers, and the like.

  Examples of ether ester type nonionic surfactants include polyoxyethylene ethers of glycerin esters, polyoxyethylene fatty acid esters (for example, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyoxyethylene). Hydrogenated castor oil), polyoxyethylene sorbitan fatty acid ester (for example, polyoxyethylene sorbitan monococonut oil fatty acid ester, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxy Ethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, Polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan mono coconut fatty acid ester, polyoxyethylene sorbit tetraoleate), include polyoxyethylene ethers of sorbitol esters.

  Ester-type nonionic surfactants include sorbitan fatty acid esters (eg sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate) Acid), glycerin fatty acid ester (for example, glycerol monostearate, glycerol monooleate), polyglycerin ester, sorbitan ester, propylene glycol ester, sucrose ester and the like.

  Nitrogen-containing nonionic surfactants include fatty acid alkanolamides (for example, coconut fatty acid diethanolamide), polyoxyethylene alkylamines (for example, polyoxyethylene laurylamine), polyoxyethylene alkylamides (for example, polyoxyethylene). Ethylene lauric acid amide) and the like. Moreover, a fluorine-type surfactant, an acetylene containing nonionic surfactant (For example, diisobutyl dimethyl butynediol polyoxyethylene glycol ether) etc. are mentioned.

  Cationic surfactants include alkylamine salts (for example, coconut amine acetate, stearylamine acetate), quaternary ammonium salts (for example, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyl). Dimethylammonium chloride, alkylbenzyldimethylammonium chloride), alkylpyridinium salts (for example, cetylpyridinium chloride) and the like.

  Amphoteric surfactants include alkylbetaine types (for example, lauric betaine (lauryldimethylaminoacetic acid betaine, stearylbetaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine), amine oxide type (for example, lauryl). Dimethylamine oxide) and the like.

Among the above surfactants, an anionic surfactant and a nonionic surfactant are more preferable in an acidic to neutral pH range, and an anionic surfactant can be more 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. Examples of the surfactant having a phenyl group and a sulfo group at the same time include alkylbenzene sulfonic acid, alkyl diphenyl ether disulfonic acid, and salts thereof, and among these, alkylbenzene sulfonic acid is particularly preferable.

  Here, one of the preferable embodiments of the polishing composition of the present invention is an inorganic abrasive (eg, silica or alumina) that exhibits a positive zeta potential under the condition of pH 5 or lower from the viewpoint of improving the polishing rate. Inorganic abrasive grains) and an anionic surfactant as described above are used in combination. When the polishing composition of the present invention takes such an embodiment, its action is not clear, but the anionic surfactant is adsorbed on the polyimide film exhibiting a negative zeta potential, and the anionic surfactant It is considered that the polishing rate when CMP is performed is further improved by the strong interaction between the agent and the inorganic abrasive grains exhibiting a positive zeta potential.

  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 in the case of using the surfactant is preferably 0.0001 g to 10 g, more preferably 0.0005 g to 5 g in 1 L of the polishing liquid when used for polishing as a total amount. It is especially preferable to set it as 0.0005g-3g.

<Chelating agent>
The polishing composition 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-dihydroxybenzene-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 in 1 L of the polishing composition when used for polishing 0.07 mol is added.

[Polishing method]
The polishing method of the present invention is a polishing method for chemically and mechanically polishing an object to be polished including a polyimide film using the polishing composition of the present invention in a semiconductor device manufacturing process.
More specifically, in the polishing method of the present invention, the polishing composition of the present invention is supplied to a polishing pad on a polishing platen, and the polishing pad is rotated so that the polishing pad contains a polyimide film. Polishing is performed by making a relative movement while being in contact with the surface to be polished of the object to be polished.
Hereinafter, the polishing method of the present invention 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) including a polyimide film as a surface to be polished, and a motor or the like having a polishing pad attached (a motor capable of changing the number of rotations). A general polishing apparatus provided with a polishing surface plate (attached) can be used. As such an apparatus, for example, FREX300 (Ebara Works) 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 Pa to 25000 Pa, and more preferably 6500 Pa to 14000 Pa.

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

(Polishing liquid supply method)
In the polishing method of the present invention, the polishing composition of the present invention is continuously supplied to the polishing pad on the polishing surface plate with a pump or the like while the surface to be polished having the polyimide film to be polished is polished. 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. As a result, the polishing composition is uniformly distributed on the surface to be polished, and high flatness after polishing can be realized.

  In the polishing method of the present invention, the concentrated polishing composition can be diluted with water or an aqueous solution. As a dilution method, for example, a pipe for supplying a concentrated polishing composition and a pipe for supplying water or an aqueous solution are joined together and mixed, and the diluted polishing composition is supplied to the polishing pad. And the like. 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.

As another dilution method, a pipe for supplying a polishing composition 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 object to be polished are supplied. A method of mixing by relative movement of the surface can also be used in the present invention.
Further, the present invention also includes a method in which a predetermined amount of a concentrated polishing composition 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.

  In addition to these methods, the method of dividing the components to be contained in the polishing composition into at least two constituent components and using them for dilution by adding water or an aqueous solution and supplying them to the polishing pad is also included in the present invention. Can be used. When an oxidizing agent is used, it may be preferable to divide it into two components from the viewpoint of the 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 composition may be used as a concentrated liquid and supplied to the polishing surface separately from the dilution water.

(Supply amount of polishing composition)
In the polishing method of the present invention, the supply amount of the polishing composition onto the polishing surface plate is preferably 50 ml / min to 500 ml / min, and more preferably 100 ml / min to 300 ml / min.

(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 that can be used in the present invention may further 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.

(Polished object)
As an object to be polished having a polyimide film to which the polishing method of the present invention can be applied, for example, a barrier metal film formed on the entire surface of an interlayer insulating film having recesses, and the recesses on the surface of the barrier metal film. And a conductive film made of copper or a copper alloy formed so as to be buried, 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 and is preferably an LSI having a wiring made of copper metal and / or a copper alloy, and the wiring is particularly preferably a copper alloy.
As an object to be polished, a wafer in which a conductive material film is formed on a support substrate, a laminate in which a conductive material film is formed on an interlayer insulating film provided on a wiring formed on the support substrate, and the like Any material having a polyimide film on the surface to be polished can include materials at all stages that require planarization in the semiconductor device manufacturing process.

  The present invention will be specifically described below with reference to examples. The present invention is not limited by these examples.

(Polished object)
In this embodiment, an object to be polished (substrate, wafer) to be polished will be described.
In this embodiment, 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 12-inch wafer in which a Cu film was formed on the Si film was prepared.

[Examples 1 to 10, Comparative Examples 1 to 6]
As polishing compositions (polishing liquids) of Examples 1 to 10 and Comparative Examples 1 to 6, polishing liquids 101 to 110 and polishing liquids 201 to 206 were respectively prepared with the compositions shown below, and polishing tests and evaluations were performed. It was.

(Preparation of polishing composition)
The following compositions were mixed to prepare polishing liquids 101 to 110 and polishing liquids 201 to 206.
-Composition of polishing composition-
Abrasive grains: 40 g / L of abrasive grains shown in Table 1
Organic solvent 1: Compound shown in Table 1 Addition amount shown in Table 1 Organic solvent 2: Compound shown in Table 1 Addition amount shown in Table 1 Oxidant: Compound shown in Table 1 Addition amount shown in Table 1 pH adjustment Agent: Compound shown in Table 1 Amount reaching target pH-Anticorrosive: Compound shown in Table 1 Addition amount shown in Table 1 Add pure water to make a total volume of 1000 ml, adjust the pH as shown in Table 1, and polish A composition was obtained.
In Table 1, TMAH is tetramethylammonium hydroxide, and PGMEA is propylene glycol monomethyl ether acetate.

(Polishing test)
Polishing was performed under the following conditions, and the polishing rate was evaluated.
・ Polishing equipment: FREX300 (Ebara Works)
-Polishing object (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): 2.5 psi
Polishing liquid supply speed: 300 ml / min
Polishing platen rotation speed: 90rpm
Polishing head rotation speed: 85 rpm

(Evaluation methods)
1. Polishing rate Calculation of polishing rate: The substrate 1 (substrate with polyimide film) was polished for 1 minute, and the polishing rate (μm / min) was calculated from the following formula from the change in film thickness of the polyimide film before and after polishing. The obtained results are shown in Table 1.
Polishing rate (μm / min) = (Polyimide film thickness before polishing−Polyimide film thickness after polishing) / Polishing time [1 minute]

2. Evaluation of 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 with AFM, and the flatness was evaluated based on the following evaluation criteria. The obtained results are shown in Table 2.
-Evaluation criteria-
○: Has flatness with no practical problem ×: Observed irregularities in the polished surface

3. Polishing 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 (polishing scratches) were evaluated based on the following evaluation criteria. The obtained results are shown in Table 1.
-Evaluation criteria-
Yes: No scratches in the polished surface were observed No: Many scratches in the polished surface were observed

  As is clear from Table 2, Examples 1 to 10 using the polishing composition of the present invention have a high polishing rate, excellent flatness of the polished surface after polishing, and polishing scratches. It can be seen that the polyimide film can be polished by CMP without causing any defects. On the other hand, it is confirmed that Comparative Examples 1 to 6 which do not use the polishing composition of the present invention are not preferable because the polishing rate is low, the flatness after polishing is poor, and polishing scratches are generated. It was. In Comparative Examples 2 to 4 using a nonpolar organic solvent, the polishing liquid was separated.

[Example 11]
Regarding the polishing liquids 101 to 110 in Examples 1 to 10, the immersion test of the wafer with the Cu film was performed at 40 ° C. for 15 minutes, and the surface state was observed with an optical microscope and AFM, but no film surface roughness was observed. It was. As a result, the polishing composition of the present invention polishes the polyimide film at high speed, has excellent flatness, has no generation of polishing flaws, and causes film surface roughness on adjacent metal wiring portions. Not confirmed.

Claims (8)

  Used for chemical mechanical polishing of polyimide films, (A) abrasive grains, (B) water, (C) aprotic organic solvent compatible with (C1) water and (C2) compatible with water A polishing composition comprising: at least one organic solvent selected from the group of protic organic solvents having:   The polishing composition according to claim 1, wherein the (A) abrasive grain is at least one selected from alumina and silica.   The polishing composition according to claim 1 or 2, wherein the (C1) water-compatible aprotic organic solvent is one selected from methyl ethyl ketone, tetrahydrofuran, dioxane, and N-methylpyrrolidone. .   The polishing composition according to claim 1 or 2, wherein the (C2) water-compatible protic organic solvent is one selected from methanol, ethanol, and ethylene glycol.   The polishing composition according to any one of claims 1 to 4, further comprising (D) a metal anticorrosive.   Furthermore, (E) Polishing composition of any one of Claims 1-5 containing an oxidizing agent.   The (E) oxidizing agent is hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate The polishing composition according to claim 6, selected from the group consisting of, dichromate, permanganate, ozone water, silver (II), and iron (III) salt.   A polishing method in which a polishing target including a polyimide film is chemically and mechanically polished using the polishing composition according to any one of claims 1 to 7 in a semiconductor device manufacturing process.