JP2006190890A - Polishing solution and polishing method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polishing solution capable of improving the yield by raising polishing speed and of realizing high flatness by the prevention of dishing, while preventing a scratch and surface roughness, at the time of polishing the metal layer of a wiring section, and to provide a chemical mechanical polishing method using the polishing solution. <P>SOLUTION: The polishing solution contains at least one kind of derivative selected out of a tetrazole derivative and an anthranilic acid derivative along with containing at least two sorts of grains whose hardness are different. The chemical mechanical polishing method uses the polishing solution. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polishing liquid, particularly a polishing liquid for chemical mechanical polishing, a polishing method using the same, and a method for manufacturing a semiconductor device. More specifically, it is caused by minute polishing scratches called scratches or excessive polishing called dishing that occur during chemical mechanical polishing (hereinafter referred to as “CMP”) of a metal layer on a wiring pattern in the manufacture of semiconductor devices. The present invention relates to a chemical mechanical polishing polishing liquid and a polishing method capable of reducing dents.

  With the remarkable development of the electronics industry, devices have evolved into transistors, ICs, LSIs (semiconductor integrated circuits), and ultra LSIs, and various fine processing technologies have been researched and developed for higher integration and higher performance. . In order to achieve high integration and high performance of semiconductor devices, it is very effective to reduce the size of individual elements such as transistors, and to form thin interconnects between them, and to make a multilayer structure. It is. However, when the wiring structure is made multi-layered, problems such as the fact that the wiring as designed cannot be assembled due to the unevenness of each layer and the reliability of the device is greatly reduced such as causing a short circuit during use may occur. As a means for solving these problems, attention has been paid to CMP that realizes high flatness by polishing irregularities of a metal layer of a wiring portion in each layer with a polishing liquid (slurry) and a polishing cloth (pad). Conventionally, tungsten and aluminum have been widely used in interconnect structures as wiring metals. However, LSIs using copper, which has lower wiring resistance than these metals, have been developed with the aim of achieving higher performance. At present, Cu (copper) having a low electric resistance is used as a wiring metal, and a Cu-CMP slurry for polishing a copper layer of the wiring is actively researched.

  As a general CMP slurry, a slurry in which inorganic particles such as alumina and silica are dispersed in water is mainly studied. However, some metal layers and metal oxide layers have low hardness, and when polished with inorganic particles having higher hardness, scratches (scratches) may be generated on the surface of the metal layer or metal oxide layer, or the particles themselves may be layered. Problems such as being buried inside may occur. In order to avoid these problems, a slurry using particles made of an organic resin having low hardness as an abrasive has been studied. However, a slurry using these soft resin particles as an abrasive causes a new problem that the yield is very low because the polishing rate is low. There is also a method of adding a chemical reagent that effectively etches the metal surface in order to compensate for the decrease in the polishing rate of the resin particles. However, the addition of these chemical reagents improves the polishing rate, but the surface becomes rough due to corrosion of the chemical reagent, and excessive polishing (dishing) in wiring parts and connection holes becomes severe, increasing the wiring resistance of the device and disconnection. Another problem occurs.

  Therefore, in order to solve these problems, as a metal film polishing slurry made of various metals or metal alloys, a CMP slurry containing both inorganic particles and organic particles as an abrasive is disclosed in Patent Document 1. Yes. In this slurry, since the organic particles act as a buffer material for effective polishing of the inorganic particles, it is said that excessive pressure on the abrasive can be prevented and scratches can be reduced. Further, Patent Document 2 discloses a CMP slurry containing a preservative benzotriazole in a composition containing both inorganic particles and organic particles as an abrasive. Since benzotriazole forms a reaction protective film on the oxidized metal film and moderately suppresses etching, this slurry can prevent surface roughness in addition to the above effects.

  However, in recent years, development of a slurry for CMP capable of realizing higher flatness and higher polishing rate has been desired for further miniaturization and multilayering of metal wiring.

JP-A-9-285957 JP 2003-277779 A

  Therefore, the present invention improves the polishing rate, and prevents polishing and surface roughness when polishing the metal layer of the wiring portion, and a polishing liquid (slurry) capable of realizing high flatness by preventing dishing, and the polishing liquid (slurry) An object is to provide a polishing method used.

  As a result of intensive studies, the present inventor has achieved the above-described problems with the following polishing liquid and a polishing method using the same.

(1) It contains at least one kind selected from a tetrazole derivative represented by the general formula (1) and an anthranilic acid derivative represented by the general formula (II), and contains at least two kinds of abrasive grains having different hardnesses. A characteristic polishing liquid.

In formula (I), R ₁ and R ₂ each independently represents a hydrogen atom or a substituent. R ₁ and R ₂ may be bonded to each other to form a ring. In addition, when R < ₁ > and R < ₂ > are hydrogen atoms simultaneously, the compound represented with general formula (I) may be the tautomer.
In formula (II), in formula, R < ₃ > -R < ₈ > represents a hydrogen atom or a substituent each independently. Two adjacent ones of R _{3 to} R ₆ may be bonded to each other to form a ring. M ⁺ represents a cation.

(2) The polishing liquid according to (1) above, wherein at least two kinds of abrasive grains having different hardnesses are (A) inorganic particles and (B) organic particles.

(3) The polishing liquid according to (1), wherein the at least two types of abrasive grains having different hardnesses are (A) metal oxide and (B) organic polymer particles.
(4) The polishing liquid according to (1), wherein the two types of abrasive grains are abrasive grains selected from the following group A and abrasive grains selected from the group B.
Group A: fumed silica, colloidal silica, synthetic silica, ceria, alumina, titania, zirconia, germania, manganese oxide, and silicon carbide.
Group B: polystyrene and styrene copolymer, (meth) acrylic resin and acrylic copolymer, polyvinyl chloride, polyacetal, saturated polyester, polyamide, polyimide, polycarbonate, phenoxy resin, polyethylene, polypropylene, poly-1-butene Polyolefins and olefin copolymers of poly-4-methyl-1-pentene, phenol resins, urethane resins, urea resins, melamine resins, epoxy resins, and alkyd resins.

(5) The average particle size of the high hardness abrasive grains in at least two types of abrasive grains having different hardnesses is 0.01.
Any one of the above (1) to (4), wherein the average particle size of the low-hardness abrasive grains is 2 to 50 times the average particle size of the high-hardness abrasive grains The polishing liquid as described.
(6) The high hardness abrasive grain concentration is 0.1 to 20% by mass, and the low hardness abrasive grain concentration is 0.1 to 10 times the high hardness abrasive grain concentration. The polishing liquid according to any one of (1) to (5) above.

(7) The polishing liquid according to any one of (1) to (6), further comprising an oxidizing agent.
(8) Chemical mechanical characterized in that the polishing liquid according to any one of (1) to (7) is brought into contact with the surface to be polished, and the surface to be polished and the polishing surface are moved relative to each other for polishing. Polishing method.

  The polishing liquid of the present invention is a polishing liquid used for chemical mechanical polishing particularly in the manufacture of semiconductor devices, and improves the polishing rate, prevents scratches and surface roughness when polishing the metal layer of the wiring portion, and prevents dishing. High flatness can be realized by prevention, and the yield and productivity of semiconductor devices can be improved.

  Hereinafter, specific embodiments of the present invention will be described.

In this specification, “concentration” and “concentrated liquid” are used in accordance with conventional expressions meaning “thick” and “thick liquid” rather than the state of use, and physical concentration operations such as evaporation are performed. It is used in a different way from the meaning of the general terms involved.
That is, the concentrated liquid or the concentrated polishing liquid means a polishing liquid prepared with a higher solute concentration than the polishing liquid used for polishing, and when used for polishing, water or an aqueous solution is used. It is diluted and used for polishing. The dilution factor is generally 1 to 20 volume times.
In the present invention, the “polishing liquid” means not only a polishing liquid used for polishing (that is, a polishing liquid diluted as necessary) but also a concentrated liquid of the polishing liquid.

The polishing liquid of the present invention has at least one selected from a tetrazole derivative represented by the general formula (I) and an anthranilic acid derivative represented by the general formula (II) as a constituent component, and at least two kinds having different hardnesses. Usually, it is an aqueous solution containing an abrasive, preferably containing an oxidizing agent.
The polishing liquid of the present invention may further contain other components, and examples of preferable components include organic acids, inorganic acids, surfactants, water-soluble polymers, and additives.
Each of the above components contained in the polishing liquid may be used alone or in combination of two or more.

  Hereinafter, each component will be described.

[Tetrazole derivative represented by general formula (I) and anthranilic acid derivative represented by general formula (II)]

In formula (I), R ₁ and R ₂ each independently represents a hydrogen atom or a substituent. R ₁ and R ₂ may be bonded to each other to form a ring. In addition, when R < ₁ > and R < ₂ > are hydrogen atoms simultaneously, the compound represented with general formula (I) may be the tautomer.
In formula (II), R _{3 to} R ₈ each independently represents a hydrogen atom or a substituent. Two adjacent ones of R _{3 to} R ₆ may be bonded to each other to form a ring. M ⁺ represents a cation.

  In addition, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes the thing which has a substituent with the thing which does not have a substituent. . For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

Although the substituent as R < ₁ > and R < ₂ > in Formula (I) is not specifically limited, For example, the following are mentioned.

  Halogen atom (fluorine atom, chlorine atom, bromine atom or iodine atom), alkyl group (straight chain, branched or cyclic alkyl group, and active methine group even if it is a polycyclic alkyl group such as a bicycloalkyl group) ), Alkenyl group, alkynyl group, aryl group, heterocyclic group (regarding the position of substitution), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group (substituent) Examples of the carbamoyl group having an N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group), carbazoyl group, carboxy Group or a salt thereof, oxalyl group, oxamoy Group, cyano group, carbonimidoyl group (Carbonimidoyl group), formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit), 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, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoyl Amino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, hydroxyamino group, A nitro group, a heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic) thio group , (Alki , Aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group (sulfamoyl group having a substituent) Moyl group, N-sulfonylsulfamoyl group) or a salt thereof, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl group and the like.

The active methine group means a methine group substituted with two electron-withdrawing groups. Examples of the electron-withdrawing group include an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, and an alkyl group. A sulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, and a carbonimidoyl group (Carbonimidoyl group) are 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 include, for example, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, or iodine atoms), alkyl groups (straight chain, branched or cyclic alkyl groups, and polycyclic groups such as bicycloalkyl groups). An 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, an aryloxycarbonyl group, hetero Ring oxycarbonyl group, carbamoyl group, N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, oxalyl group, Oxamoyl group, cyano group, carboximide Group (Carbonimide group), formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) A carbonyloxy group, a carbamoyloxy group, a sulfonyloxy group, an (alkyl, aryl, or heterocyclic) amino group, an acylamino group, a sulfonamide group, a ureido group, a thioureido group, an N-hydroxyureido group, an 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-acylureido 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, 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, sulfamoy Group, N- acylsulfamoyl group, N- sulfonylsulfamoyl group or a salt thereof, a phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, and a silyl group. 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 (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).

The ring formed by combining R ₁ and R ₂ together with the —C—N— bond in formula (I) may be monocyclic or polycyclic, preferably a 5- to 6-membered ring. Or a polycyclic ring composed of a 5- to 6-membered ring.

  The above substituent may be further substituted with the above substituent.

  The molecular weight of the compound represented by the general formula (I) is preferably 20 to 600, more preferably 40 to 400.

  Specific examples of the compound represented by the general formula (I) are shown below, but are not limited thereto.

Among the compounds represented by the general formula (I), preferred are compounds I-1, I-3, I-4, I-10, I-15, I-21, I-22, I-23. , I-41 and I-48, and compounds I-1, I-4, I-15, I-22 and I-23 are more preferable.
Moreover, the compound represented by general formula (I) may be used independently, and may be used together 2 or more types.

  The compound represented by the general formula (I) can be synthesized according to a conventional method, or a commercially available product may be used.

Although the substituent as R < ₃ > -R < ₈ > in Formula (II) is not specifically limited, For example, the following are mentioned.

  Halogen atom (fluorine atom, chlorine atom, bromine atom or iodine atom), alkyl group (straight chain, branched or cyclic alkyl group, and active methine group even if it is a polycyclic alkyl group such as a bicycloalkyl group) ), Alkenyl group, alkynyl group, aryl group, heterocyclic group (regarding the position of substitution), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group (substituent) Examples of the carbamoyl group having an N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group), carbazoyl group, carboxy Group or a salt thereof, oxalyl group, oxamoy Group, cyano group, carbonimidoyl group (Carbonimidoyl group), formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit), 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, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoyl Amino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, hydroxyamino group, A nitro group, a heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic) thio group , (Alki , Aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group (sulfamoyl group having a substituent) Moyl group, N-sulfonylsulfamoyl group) or a salt thereof, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl group and the like.

  The active methine group means a methine group substituted with two electron-withdrawing groups. Examples of the electron-withdrawing group include an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, and an alkyl group. A sulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, and a carbonimidoyl group (Carbonimidoyl group) are 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.

  These substituents may be further substituted with these substituents.

Among these, as preferred substituents, at least one of R _{3 to} R ₆ is a substituent other than an alkyl group having no substituent, and more preferably, each of R _{7 to} R ₈ is a hydrogen atom. . Particularly preferably, at least one of R _{3 to} R ₆ is the above-described electron-withdrawing group, and each of R _{7 to} R ₈ is a hydrogen atom.

The cation as M ⁺ is not particularly limited. For example, hydrogen ion, alkali metal ion (eg, Na ⁺ , K ⁺ , Li ^+, etc.), ammonium ion (eg, NH ₄ ⁺ , quaternary ammonium ion, etc.) Can be mentioned.

  The molecular weight of the compound represented by the general formula (II) is preferably 20 to 600, more preferably 40 to 400.

  Specific examples of the compound represented by the general formula (II) are shown below, but are not limited thereto.

  Among the above compounds, II-2, II-5, II-9, II-27, II-29, II-30, II-33, II-35 and II-37 are preferred, and II-5, II -9, II-27, II-29 and II-33 are particularly preferred.

Further, examples include salts obtained by substituting the hydrogen atom of the carboxy group in the above exemplary compounds with Na ⁺ , K ⁺ , Li ⁺ , or ammonium ions (for example, ammonium ions such as NH ₄ ⁺ or quaternary ammonium ions). it can.

  Moreover, the compound represented by general formula (II) may be used independently, and may be used together 2 or more types.

The compound represented by the general formula (II) may be a commercially available product or may be synthesized according to a conventional method.
For example, Compound II-29 can be synthesized according to the synthesis method described in Synthesis (8), 654-659 (1983). Compound II-37 was prepared according to Tetrahedron Letters, 51 (7), 1861-1866 (1995).
And Tetrahedron Letters, 44 (25), 4741-4745 (2003). Other compounds can also be synthesized according to the methods described therein.

  The total amount of the compound represented by the general formula (I) or (II) (tetrazole derivative and anthranilic acid derivative) is a polishing liquid used for polishing (ie, diluted with a solvent after dilution). Polishing liquid. 0.001 to 1.0 mol is preferable, more preferably 0.001 to 0.5 mol, and still more preferably, in 1 L of “polishing liquid when used for polishing”. 0.01 to 0.5 mol. That is, the addition amount of the compound represented by the general formula (I) or (II) is from the viewpoint of preventing deterioration (ineffective, decomposition) of the oxidizing agent and the compound represented by the general formula (I) or (II). 1.0 mol or less is preferable in 1 L of polishing liquid, and 0.0001 mol or more is preferable for obtaining a sufficient effect. The thiocyanate, thioether, thiosulfate or meso ion compound may be used in combination with an addition amount smaller than the addition amount of the compound represented by formula (I) or (II).

[Abrasive]
The polishing liquid of the present invention contains at least two kinds of abrasive grains having different hardness. The hardness described here is a 10 μm particle having the same composition as the used particle, and 10% of the particle diameter is displaced at 20 ° C. in a micro compression tester (for example, “MCT-500W” manufactured by Shimadzu Corporation). When the load (strength) applied when displacing 10% of the particle size differs by 3 MPa or more between the particles, the particle hardness is defined as different.

  That is, for the abrasive grains contained in the polishing liquid of the present invention, the hardness difference between the abrasive grains having the highest hardness and the abrasive grains having the lowest hardness is 3 MPa or more, more preferably 10 MPa or more, and further preferably 20 MPa or more. That is, the hardness difference between the low hardness particles and the high hardness particles is 3 MPa or more for the purpose of sufficiently exerting the function of the buffer material of the low hardness particles and reducing the occurrence of scratches.

  The hardness of the abrasive grains contained in the polishing liquid of the present invention is preferably 20 to 2000 MPa. More preferably, it is 20-1000 MPa, More preferably, it is 30-500 MPa. That is, the hardness is preferably 20 MPa or more in order to prevent a significant decrease in polishing force, and the hardness of 2000 MPa or less is preferable for the purpose of sufficiently exerting the function of a buffer material for low-hardness particles and reducing the occurrence of scratches.

  The two or more types of abrasive grains having different hardnesses are preferably selected from at least one of (A) inorganic particles and (B) organic particles. More preferably, the inorganic particles are metal oxides, and the organic particles are organic polymer particles.

Specifically, the inorganic particles include at least one kind of inorganic particles selected from fumed silica, colloidal silica, synthetic silica, ceria, alumina, titania, zirconia, germania, manganese oxide, silicon carbide, etc., or any of them. Combinations can be used. The number and ratio to be combined can be arbitrarily selected without limitation. Fumed silica, colloidal silica, alumina and titania are preferable, and colloidal silica is more preferable.

  Specific examples of the organic particles include polystyrene and styrene copolymer, (meth) acrylic resin and acrylic copolymer, polyvinyl chloride, polyacetal, saturated polyester, polyamide, polyimide, polycarbonate, phenoxy resin, polyethylene, polypropylene, Poly-1-butene, poly-4-methyl-1-pentene polyolefin and olefin copolymer, phenolic resin, urethane resin, urea resin, melamine resin, epoxy resin, alkyd resin, etc. Particles or any combination of these can be used. The number and ratio to be combined can be arbitrarily selected without limitation. Preferably polystyrene and styrene copolymer, (meth) acrylic resin and acrylic copolymer, polyvinyl chloride, polyacetal, saturated polyester, polyamide, polyimide, polycarbonate, phenoxy resin, polyethylene, polypropylene, poly-1-butene, Poly-4-methyl-1-pentene polyolefins, olefin copolymers, and melamine resins are desirable. More preferably, (meth) acrylic resin and acrylic copolymer, polyvinyl chloride, polyacetal, saturated polyester, polyamide, polyimide, polycarbonate, phenoxy resin, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1 -Polyolefins and olefinic copolymers of pentene are desirable.

Since the organic particles in the present invention are considerably softer than the inorganic particles themselves, the polishing force on the metal layer is very small compared to the inorganic particles. However, if the inorganic particles adhere to the organic particles in the polishing liquid and the inorganic-organic particle composite particles are formed in the polishing liquid, the effective particle size of the inorganic particles increases, improving the polishing rate and improving the scratch rate. It is also possible for the particles to be reduced simultaneously. Such composite particles may be formed by electrostatic interactions derived from surface functional groups such as carboxyl groups, sulfonic acid groups, hydroxyl groups, amino groups, etc. of polymer particles, or alkoxysilanes. In addition, aluminum alkoxide, titanium alkoxide or the like may be present and chemically bonded by an additive such as a silane coupling agent.
Such interaction or the like does not work, and inorganic particles and organic particles may exist alone, and may individually have an effect on polishing.

As described above, the polishing liquid of the present invention contains at least two kinds of abrasive grains different by 3 MPa or more, that is, “high hardness abrasive grains” and “low hardness abrasive grains”.
Here, “high hardness abrasive grains” means abrasive grains having a hardness of 3 MPa or more higher than certain abrasive grains present in the polishing liquid, and “low hardness abrasive grains” means “high hardness abrasive grains”. ”Means all abrasive grains having a hardness of 3 MPa or more. In other words, “low hardness abrasive grains” are determined by determining “high hardness abrasive grains” on the assumption that there are abrasive grains having a hardness of 3 MPa or more. In addition to “high hardness abrasive grains” and “low hardness abrasive grains”, the polishing liquid has higher hardness than “high hardness abrasive grains” and “high hardness abrasive grains”. Abrasive grains having a low hardness in the range of less than 3 MPa may exist.
The “high hardness abrasive grains” are preferably 20 to 80 mass%, more preferably 40 to 60 mass%, based on the amount of the total abrasive grains.
The total amount of the “high hardness abrasive grains” and the “low hardness abrasive grains” is preferably 50 to 100 mass%, more preferably 80 to 100 mass%, based on the total abrasive grains.

The average particle size of the “high hardness abrasive grains” is preferably 0.01 to 1 μm, more preferably 0.01 to 0.5 μm. The polishing force when polishing the metal layer is sufficiently large, and 0.01 μm or more is preferable for the purpose of preventing generation of unpolished metal on the surface to be polished. Moreover, 1 micrometer or less is preferable from a viewpoint of generation | occurrence | production of a scratch and the dispersibility to a solvent.
In addition, the average particle diameter of an abrasive grain can be measured with the said micro compression tester (For example, "MCT-500W" by Shimadzu Corporation).

  The average particle diameter of the “low hardness abrasive grains” is preferably 2 to 50 times, more preferably 2 to 20 times the average particle diameter of the “high hardness abrasive grains”. The buffering effect against excessive polishing applied to the high-hardness particles when polishing the metal layer is sufficiently exhibited, and is preferably twice or more for the purpose of suppressing scratches on the semiconductor wafer. Further, the particle diameter is preferably 50 times or less for the purpose of not only sufficiently exhibiting the polishing effect of the inorganic particles and preventing the reduction of the polishing rate but also obtaining good dispersibility in the solvent.

  The concentration of “high hardness abrasive grains” is preferably contained in the polishing liquid at a ratio of 0.1 to 20 mass%. More preferably, it is 0.1-10 mass%. The concentration is preferably 0.1% by mass or more for the purpose of having a sufficiently large polishing force when polishing the metal layer and preventing generation of unpolished metal on the surface to be polished. The concentration is preferably 20% by mass or less for the purpose of reducing scratches on the semiconductor wafer and suppressing dishing.

The concentration of “low hardness abrasive grains” is preferably 0.1 to 10 times the concentration of “high hardness abrasive grains”. More preferably, it is 1 to 10 times. The buffering effect against excessive polishing applied to the high-hardness particles when polishing the metal layer is sufficiently exhibited, and is preferably 0.1 times or more for the purpose of suppressing scratches on the semiconductor wafer. Further, it is preferably 10 times or less for the purpose of sufficiently exerting the polishing effect of the inorganic particles and preventing the reduction of the polishing rate.
In the “low hardness abrasive grains”, the ratio of abrasive grains 10 MPa or more lower than “high hardness abrasive grains” is preferably 5 to 100 mass%, and the ratio of abrasive grains 20 MPa or more lower is 3 to 100%. More preferably, it is mass%.

〔Oxidant〕
The polishing liquid of the present invention preferably contains a compound (oxidant) capable of oxidizing the metal to be polished. Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, Bichromate, permanganate, ozone water and silver (II) salt, iron (III) salt are mentioned. Examples of iron (III) salts include inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III), iron bromide (III), and organic iron (III) salts. Complex salts are preferably used.

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

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

Among them, hydrogen peroxide, iodate, hypochlorite, chlorate, and an organic complex salt of iron (III) are preferable, and a preferable complex-forming compound in the case of using an organic complex salt of iron (III) is citric acid, Tartaric acid, aminopolycarboxylic acid (specifically, ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid , Ethylenediamine-N, N′-disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylateethyl) -L-aspartic acid, N- (carboxymethyl) -L-aspartic acid , Β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).
Among the oxidizing agents, hydrogen peroxide and iron (III) ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid and ethylenediaminedi A succinic acid (SS body) complex is most preferable.

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

〔acid〕
The polishing liquid of the present invention preferably further contains an acid. The acid here is a compound having a structure different from that of the oxidizing agent for oxidizing the metal, and does not include an acid that functions as the above-mentioned oxidizing agent. The acid here has an action of promoting oxidation, adjusting pH, and buffering agent. Examples of acids include inorganic acids, organic acids, and amino acids within that range. Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid, and carbonic acid. Among inorganic acids, phosphoric acid and carbonic acid are preferable.
In the present invention, organic acids and amino acids are particularly preferably present, and amino acids are more preferable. As the organic acid, one selected from the following group is more suitable. Formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid , N-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, Examples thereof include tartaric acid, citric acid, lactic acid, and salts thereof such as ammonium salt and alkali metal salt, sulfuric acid, nitric acid, ammonia, ammonium salts, or a mixture thereof. Among these, formic acid, malonic acid, malic acid, tartaric acid, and citric acid are suitable for a laminated film including at least one metal layer selected from copper, a copper alloy, and an oxide of copper or a copper alloy.

  The amino acid is preferably water-soluble. Those selected from the following group are more suitable. For example, glycine, L-alanine, β-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L- Proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-tyrosine, 3,5-diodo-L-tyrosine, β- ( 3,4-dihydroxyphenyl) -L-alanine, L-thyroxine, 4-hydroxy-L-proline, L-cystine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-cystine, L- Cystic acid, L-aspartic acid, L-glutamic acid, S- (carboxymethyl) -L-cysteine, 4-amino Butyric acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-kynurenine, L-histidine, 1-methyl-L-histidine, It is desirable to include at least one of amino acids such as 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipine. In particular, malic acid, tartaric acid, citric acid, glycine, and glycolic acid are preferable in that the etching rate can be effectively suppressed while maintaining a practical CMP rate.

  The addition amount of the acid is preferably 0.0005 mol to 0.5 mol, more preferably 0.005 mol to 0.3 mol, and more preferably 0.01 mol to 0 mol in 1 L of the polishing liquid used for polishing. .1 mol is particularly preferable. That is, the amount of acid added is preferably 0.5 mol or less from the viewpoint of suppressing etching, and 0.0005 mol or more is preferable for obtaining a sufficient effect.

[Chelating agent]
The polishing liquid of the present invention preferably contains a chelating agent (that is, a hard water softening agent) as necessary in order to reduce adverse effects such as mixed polyvalent 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-hydroxybe Jill) ethylenediamine -N, N'-diacetic acid, 1,2-dihydroxy-4,6-disulfonic acid.

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

〔Additive〕
Moreover, it is preferable to use the following additives for the polishing liquid of the present invention.
Ammonia; alkylamines such as dimethylamine, trimethylamine, triethylamine and propylenediamine; amines such as ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate and chitosan; dithizone, cuproin (2,2'-biquinoline), neocuproin (2, Imines such as 9-dimethyl-1,10-phenanthroline), bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and cuperazone (biscyclohexanone oxalyl hydrazone); benzimidazole-2-thiol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl)] thiobutyric acid, 2-mercaptobenzothiazole, 1,2,3-triazole, 1,2,4- Triazole, 3-amino-1H-1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4- Carboxyl-1H-benzotriazole, 4-methoxycarbonyl-1H-benzotriazole, 4-butoxycarbonyl-1H-benzotriazole, 4-octyloxycarbonyl-1H-benzotriazole, 5-hexylbenzotriazole, N- (1,2 , 3-Benzotriazolyl-1-methyl) -N- (1,2,4-triazolyl-1-methyl) -2-ethylhexylamine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) Chill] azole such as phosphonic acid; nonyl mercaptan, dodecyl mercaptan, triazine thiol, triazine dithiol, mercaptan triazine trithiol etc., other, anthranilic acid, Aminotoruiru acid, quinaldic acid. Among these, chitosan, ethylenediaminetetraacetic acid, L-tryptophan, cuperazone, triazinedithiol, benzotriazole, 4-hydroxybenzotriazole, 4-carboxyl-1H-benzotriazole butyl ester, tolyltriazole, and naphthotriazole are high in CMP rate and low. This is preferable for achieving both etching rates.

  The additive amount of these additives is preferably 0.0001 mol to 0.5 mol, more preferably 0.001 mol to 0.2 mol, and more preferably 0.005 mol to 0.2 mol in 1 L of a polishing liquid used for polishing. The amount is particularly preferably 0.1 mol. That is, the addition amount of the additive is preferably 0.0001 mol or more from the viewpoint of suppressing etching, and preferably 0.5 mol or less from the viewpoint of preventing a decrease in CMP rate.

[Surfactant and / or hydrophilic polymer]
The polishing liquid of the present invention preferably contains a surfactant and / or a hydrophilic polymer. Both the surfactant and the hydrophilic polymer have the action of reducing the contact angle of the surface to be polished and the action of promoting uniform polishing. As the surfactant and / or hydrophilic polymer to be used, those selected from the following group are suitable.
Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. As the carboxylate salt, soap, N-acyl amino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxyl Acid salt, acylated peptide; as sulfonate, alkyl sulfonate, alkyl benzene and alkyl naphthalene sulfonate, naphthalene sulfonate, sulfosuccinate, α-olefin sulfonate, N-acyl sulfonate; sulfate ester Salts include sulfated oil, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkyl amide sulfates; phosphate ester salts such as alkyl phosphates, polyoxyethylene or polyoxy B pyrene alkyl allyl ether phosphate can be exemplified.

As cationic surfactant, aliphatic amine salt, aliphatic quaternary ammonium salt, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt; carboxybetaine type, aminocarboxylate as amphoteric surfactant And imidazolinium betaine, lecithin, and alkylamine oxide.
Nonionic surfactants include ether type, ether ester type, ester type and nitrogen-containing type. Ether type includes polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene poly Examples include oxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, ether ester type, glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether, ester type, Polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol ester Le, sucrose esters, nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like. Moreover, a fluorine-type surfactant etc. are mentioned.

  Furthermore, other surfactants, hydrophilic compounds, hydrophilic polymers and the like include esters such as glycerin ester, sorbitan ester, methoxyacetic acid, ethoxyacetic acid, 3-ethoxypropionic acid and alanine ethyl ester; polyethylene glycol, polypropylene glycol, Polytetramethylene glycol, polyethylene glycol alkyl ether, polyethylene glycol alkenyl ether, alkyl polyethylene glycol, alkyl polyethylene glycol alkyl ether, alkyl polyethylene glycol alkenyl ether, alkenyl polyethylene glycol, alkenyl polyethylene glycol alkyl ether, alkenyl polyethylene glycol alkenyl ether, polypropylene glycol alkyl Ete , Polypropylene glycol alkenyl ethers, alkyl polypropylene glycols, alkyl polypropylene glycol alkyl ethers, alkyl polypropylene glycol alkenyl ethers, alkenyl polypropylene glycols, alkenyl polypropylene glycol alkyl ethers and alkenyl polypropylene glycol alkenyl ethers; alginic acid, pectinic acid, carboxymethylcellulose, curd Polysaccharides such as orchid and pullulan; amino acid salts such as glycine ammonium salt and glycine sodium salt; polyaspartic acid, polyglutamic acid, polylysine, polymalic acid,

  Polymethacrylic acid, poly (ammonium methacrylate), poly (methacrylic acid sodium salt), polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic Ammonium acid salt, polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid and other salts; vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone and polyacrolein; methyl Tauric acid ammonium salt, methyl tauric acid sodium salt, methyl sodium sulfate salt, ethylammonium sulfate salt, butylammonium sulfate salt, vinylsulfonic acid sodium salt, 1-a Sulfonic acid sodium salt, 2-allylsulfonic acid sodium salt, methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, 3-ethoxypropylsulfonic acid sodium salt, methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, Examples include sulfonic acids such as 3-ethoxypropylsulfonic acid sodium salt and sulfosuccinic acid sodium salt and amides such as propionamide, acrylamide, methylurea, nicotinamide, succinic acid amide, and sulfanilamide.

  However, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, contamination with an alkali metal, an alkaline earth metal, a halide, or the like is not desirable, so an acid or an ammonium salt thereof is desirable. This is not the case when the substrate is a glass substrate or the like. Among the above exemplified compounds, cyclohexanol, polyacrylic acid ammonium salt, polyvinyl alcohol, succinic acid amide, polo vinyl pyrrolidone, polyethylene glycol, and polyoxyethylene polyoxypropylene block polymer are more preferable.

  The total amount of the surfactant and / or hydrophilic polymer added is preferably 0.001 g to 10 g and more preferably 0.01 g to 5 g in 1 L of a polishing liquid used for polishing. It is particularly preferably 0.1 to 3 g. That is, the addition amount of the surfactant and / or the hydrophilic polymer is preferably 0.001 g or more for obtaining a sufficient effect, and is preferably 10 g or less from the viewpoint of preventing the CMP rate from being lowered. Moreover, as a weight average molecular weight of these surfactant and / or hydrophilic polymer, 500-100000 are preferable, and 2000-50000 are especially preferable.

[Alkaline agent and buffer]
The polishing liquid of the present invention can contain an alkali agent for pH adjustment and further a buffering agent from the viewpoint of suppressing fluctuations in pH, if necessary.

  Alkaline agents and buffering agents include organic ammonium hydroxides such as ammonium hydroxide and tetramethylammonium hydroxide, nonmetallic alkali agents such as alkanolamines such as diethanolamine, triethanolamine, triisopropanolamine, and the like. Alkali metal hydroxides such as sodium, potassium hydroxide and lithium hydroxide, carbonate, phosphate, borate, tetraborate, hydroxybenzoate, glycyl salt, N, N-dimethylglycine salt, leucine Salt, norleucine salt, guanine salt, 3,4-dihydroxyphenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydroxyaminomethane salt Lysine salt etc. can be used .

  Specific examples of the alkali agent and buffer include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, diphosphate phosphate. Sodium, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, sodium o-hydroxybenzoate (sodium salicylate), potassium o-hydroxybenzoate, 5-sulfo Examples include sodium 2-hydroxybenzoate (sodium 5-sulfosalicylate), potassium 5-sulfo-2-hydroxybenzoate (potassium 5-sulfosalicylate), ammonium hydroxide, and the like.

  Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkaline agent and the buffering agent may be an amount that maintains the pH within a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of a polishing liquid used for polishing. More preferably, the amount is 0.003 mol to 0.5 mol. 2-14 are preferable and, as for pH of the polishing liquid at the time of using for grinding | polishing, 3-12 are more preferable. Within this range, the polishing liquid of the present invention exhibits particularly excellent effects.

[Dispersion medium]
As the polishing dispersion medium of the present invention, water alone or water as a main component (in the dispersion medium, 50 to 99% by mass), and a water-soluble organic solvent such as alcohol or glycol as a minor component (1 to 30% by mass). %) Can be used. The water is preferably pure water or ion-exchanged water that does not contain macro particles as much as possible. Examples of the alcohol include methyl alcohol, ethyl alcohol, and isopropyl alcohol, and examples of the glycol include ethylene glycol, tetramethylene glycol, diethylene glycol, propylene glycol, and polyethylene glycol. The content of the dispersion medium in the polishing liquid is 75 to 95% by mass, preferably 85 to 90% by mass. 75 mass% or more is preferable from a viewpoint of the supply property to the board | substrate of polishing liquid.

  In the present invention, depending on the adsorptivity and reactivity to the polishing surface, the solubility of the polishing metal, the electrochemical properties of the surface to be polished, the dissociation state of the compound functional group, the stability as a liquid, etc. It is preferable to set the amount, pH, and dispersion medium.

  In addition, it is preferable that the compounding quantity of the thing with the solubility with respect to the solvent in room temperature among the components added at the time of preparation of the concentrated liquid of polishing liquid is less than twice the solubility with respect to the solvent at room temperature. More preferably, it is within 5 times. If this addition amount is twice or more, it becomes difficult to prevent precipitation when the concentrate is cooled to 5 ° C.

[Wiring metal raw materials]
In the present invention, the object to be polished is preferably a wiring made of a copper metal and / or a copper alloy in a semiconductor such as LSI, and a copper alloy is particularly preferable. Furthermore, the copper alloy containing silver is preferable among copper alloys. The silver content contained in the copper alloy is preferably 40% by mass or less, particularly 10% by mass or less, more preferably 1% by mass or less, and most preferably in the range of 0.00001 to 0.1% by mass. Exhibits excellent effects.

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

[Barrier metal]
In the present invention, it is preferable to provide a barrier layer for preventing the diffusion of copper between the wiring made of copper metal and / or a copper alloy of the semiconductor and the interlayer insulating film. As the barrier layer, a low-resistance metal material is preferable, and TiN, TiW, Ta, TaN, W, and WN are particularly preferable, and Ta and TaN are particularly preferable.

[Polishing method]
The polishing liquid is a concentrated liquid that is diluted by adding water when used, or mixed in the form of an aqueous solution described in the next section for each component, and diluted by adding water as necessary. In some cases, it may be used as a working solution or prepared as a working solution. The polishing method using the polishing liquid of the present invention can be applied to any case, supplying the polishing liquid to the polishing pad on the polishing surface plate, and bringing the polishing surface and the polishing pad into relative motion by bringing them into contact with the surface to be polished. This is a polishing method for polishing.
As an apparatus for polishing, there is a general polishing apparatus having a polishing surface plate with a holder for holding a semiconductor substrate having a surface to be polished and a polishing pad attached (a motor etc. capable of changing the number of rotations is attached). Can be used. As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation. The polishing conditions are not limited, but the rotation speed of the polishing surface plate is preferably a low rotation of 200 rpm or less so that the substrate does not jump out. The pressure applied to the polishing pad of the semiconductor substrate having the surface to be polished (film to be polished) is preferably ⁵ to 500 g / cm ² in order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern. Is more preferably 12 to 240 g / cm ² .

  During polishing, a polishing liquid is continuously supplied to the polishing pad with 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. The semiconductor substrate after polishing is thoroughly washed in running water, and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like. In the polishing method of the present invention, the aqueous solution to be diluted is the same as the aqueous solution described below. The aqueous solution is water containing at least one of an oxidizing agent, an acid, an additive, and a surfactant in advance, and the total amount of the components contained in the aqueous solution and the components of the polishing liquid to be diluted is the polishing liquid. Use it as a component when polishing. When diluted with an aqueous solution and used, components that are difficult to dissolve can be blended in the form of an aqueous solution, and a more concentrated polishing liquid can be prepared.

As a method of diluting the concentrated polishing liquid by adding water or an aqueous solution, the pipe for supplying the concentrated polishing liquid and the pipe for supplying the water or the aqueous solution are joined together and mixed, and mixed and diluted. There is a method of supplying a polishing pad to a polishing pad. Mixing is a method in which liquids collide with each other through a narrow passage under pressure, a method in which a filling such as a glass tube is filled in the pipe, and the flow of liquid is repeatedly separated and merged. Conventional methods such as a method of providing blades that rotate in the above can be employed.

  The supply rate of the polishing liquid is preferably 10 to 1000 ml / min, and more preferably 170 to 800 ml / min in order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern.

  As a method of diluting the concentrated polishing liquid with water or an aqueous solution and polishing, a pipe for supplying the 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. In this method, the polishing pad and the surface to be polished are mixed while being mixed by relative movement. Alternatively, there is a method in which a predetermined amount of concentrated polishing liquid and water or an aqueous solution are mixed in one container, and then the mixed polishing liquid is supplied to a polishing pad for polishing.

According to another polishing method of the present invention, the component to be contained in the polishing liquid is divided into at least two components, and when these components are used, they are diluted by adding water or an aqueous solution and supplied to the polishing pad on the polishing platen. In this method, the surface to be polished and the polishing pad are moved relative to each other and brought into contact with the surface to be polished. For example, an oxidizing agent is one component (A), an acid, an additive, a surfactant, and water are one component (B), and when they are used, the component (A) The component (B) is diluted before use.
In addition, the low-solubility additive is divided into two components (A) and (B), and the oxidizing agent, additive and surfactant are one component (A), and the acid, additive, surfactant and Water is used as one component (B), and when these are used, water or an aqueous solution is added to dilute the component (A) and the component (B). In the case of this example, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are required, and dilution mixing is performed on one pipe that supplies the three pads to the polishing pad. There is a method of combining and mixing in the pipe. In this case, it is also possible to combine two pipes and then connect another pipe.

  For example, it is a method in which a component containing an additive that is difficult to dissolve is mixed with another component, a mixing path is lengthened to ensure a dissolution time, and then a pipe for water or an aqueous solution is further combined. Other mixing methods are as described above, in which the three pipes are each guided directly to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished, and the three components are mixed in one container. Is a method of supplying a diluted polishing liquid to the polishing pad. In the above polishing method, one constituent component containing an oxidizing agent is made 40 ° C. or lower, the other constituent components are heated in the range of room temperature to 100 ° C., and one constituent component and another constituent component or water or an aqueous solution When the mixture is diluted and used, it can be adjusted to 40 ° C. or lower after mixing. Since the solubility increases when the temperature is high, this is a preferable method for increasing the solubility of the raw material having a low solubility of the polishing liquid.

  A raw material in which other components not containing an oxidizing agent are heated and dissolved in the range of room temperature to 100 ° C. is precipitated in the solution when the temperature is lowered. It is necessary to dissolve what is deposited by heating. For this, a means for feeding a heated component solution and a means for stirring the liquid containing the precipitate, feeding the liquid, and heating and dissolving the pipe can be employed. When the temperature of one component containing an oxidant is increased to 40 ° C. or higher, the oxidant may be decomposed. Therefore, the heated component and the oxidation for cooling the heated component When mixed with one component containing an agent, the temperature is set to 40 ° C. or lower.

  In the present invention, as described above, the components of the polishing liquid may be divided into two or more parts and supplied to the polishing surface. In this case, it is preferable to divide and supply the component containing an oxide and the component containing an acid. Alternatively, the polishing liquid may be a concentrated liquid, and diluted water may be separately supplied to the polishing surface.

〔pad〕
The polishing pad 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.
Further, it may contain abrasive grains (for example, ceria, silica, alumina, resin, etc.) used for polishing. In addition, the hardness may be either soft or hard, and either may be used. In the laminated system, it is preferable to use a different hardness for each layer. The material is preferably non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate or the like. In addition, the surface contacting the polishing surface may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

[Wafer]
The target wafer to be subjected to CMP with the polishing liquid of the present invention preferably has a diameter of 200 mm or more, particularly preferably 300 mm or more. The effect of the present invention is remarkably exhibited when the thickness is 300 mm or more.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.
<Example 1>
(Preparation of polishing liquid)
Compound (I-1) 0.01% by mass
Abrasive grain 1 (Colloidal silica (1): average particle diameter 30 nm) 10% by mass
Abrasive grain 2 (acrylic resin (1): average particle diameter 135 nm) 5% by mass
Hydrogen peroxide (oxidant) 1% by mass
Glycine (acid) 0.8% by mass
pH (adjusted with aqueous ammonia and sulfuric acid) 7.0
An aqueous solution was prepared so that each component had the above concentration, and stirred with a high-speed homogenizer to uniformly disperse to obtain a polishing liquid.

<Examples 2 to 62 and Comparative Examples 1 to 5>
In the same manner as in Example 1, using the compounds and abrasive grains shown in Table 1, polishing liquids of Examples 2 to 62 and Comparative Examples 1 to 5 were prepared and subjected to a polishing test. The acid, oxidizing agent, and pH were the same as in Example 1. In addition, the density | concentration (%) of the abrasive grain in Table 1 is the mass%.

<Polishing rate evaluation>
Under the following conditions, while supplying the polishing liquid onto the polishing cloth of the polishing surface plate of the polishing apparatus, the metal film is polished by moving the polishing surface plate and the substrate relatively while pressing the substrate against the polishing cloth, The polishing rate at that time was measured.
Substrate: 4 cm × 4 cm silicon wafer with copper film Relative speed between substrate and polishing surface plate: 60 m / min Polishing pressure: 168 hPa
Polishing pad: IC1400
Polishing liquid supply rate: 50 ml / min Measurement of polishing rate: The thickness of the copper film before and after polishing was determined from the electrical resistance, and the polishing rate was calculated according to the following formula.
Polishing rate (A / min) = (thickness of copper film before polishing−thickness of copper film after polishing) / polishing time

<Polishing property evaluation>
In order to evaluate the polishing characteristics, the polishing surface plate is pressed against the polishing cloth while supplying the polishing liquid onto the polishing cloth of the polishing surface plate of the polishing apparatus under the following conditions. The metal film was polished by relatively moving the substrate and the step was measured.
Substrate: A substrate in which tantalum is used as a barrier metal film and a silicon wafer with a 1200 nm copper film in which a groove having a depth of 500 nm is formed is cut into 4 cm × 4 cm.
Relative speed between substrate and polishing platen: 60 m / min Polishing pressure: 168 hPa
Polishing pad: IC1400
Polishing liquid supply speed: 50 ml / min Step difference measurement: Using a stylus type step difference measuring instrument, the step difference was measured at a line / space of 100 μm / 100 μm.

<Scratch of copper film>
The appearance of each substrate after polishing was visually observed. The evaluation criteria were A: no scratch, B: several scratches observed, C: a clearly problematic number of scratches observed.
The evaluation results are shown in Table 1.

<Compound represented by formula (I) or (II)>
It is synthesized according to the method described in Synthesis (8), 654-659 (1983), etc., as in Compound II-29, or Wako Pure Chemical Industries, as in Compounds I-1, I-2, II-10. Commercial products such as Kogyo Co., Ltd. were used.
<Abrasive grains>
Table 2 shows the abrasive grains used in Examples and Comparative Examples.

<Average particle size of abrasive grains>
It measured with the micro compression tester (Shimadzu "MCT-500W").
<Hardness of abrasive grains>
Each particle was placed in the form of a powder having a particle size of about 10 μm on a sample plate of a micro compression tester (manufactured by Shimadzu Corporation “MCT-500W”) and compressed under a load. The pressure required to deform 10% of the particle size at 20 ° C. was defined as the strength.

According to the results of Table 1, the polishing liquids of Examples 1 to 62 containing a tetrazole derivative or an anthranilic acid derivative together with two types of abrasive grains (mixed system of organic particles and inorganic particles) having different hardnesses have a high polishing rate. Low dishing and scratches are not observed. On the other hand, it can be seen that dishing is large in Comparative Example 1 using benzotriazole (BTA) as the protective film forming material. In Comparative Example 2 in which only colloidal silica was used as the abrasive grains, many scratches were observed in addition to the decrease in the polishing rate. In Comparative Example 3 in which only divinylbenzene resin was used as the abrasive, not only the polishing rate was significantly reduced, but also dishing was a very large value. It can be seen that Comparative Examples 4 and 5 using BTA are inferior in terms of dishing and scratching even when a plurality of abrasive grains are used.

Claims (8)

It contains at least one selected from a tetrazole derivative represented by the general formula (1) and an anthranilic acid derivative represented by the general formula (II), and contains at least two kinds of abrasive grains having different hardnesses. Polishing fluid.

In formula (I), R ₁ and R ₂ each independently represents a hydrogen atom or a substituent. R ₁ and R ₂ may be bonded to each other to form a ring. In addition, when R < ₁ > and R < ₂ > are hydrogen atoms simultaneously, the compound represented with general formula (I) may be the tautomer. )
In formula (II), in formula, R < ₃ > -R < ₈ > represents a hydrogen atom or a substituent each independently. Two adjacent ones of R _{3 to} R ₆ may be bonded to each other to form a ring. M ⁺ represents a cation.   The polishing liquid according to claim 1, wherein the at least two kinds of abrasive grains having different hardnesses are (A) inorganic particles and (B) organic particles.   The polishing liquid according to claim 1, wherein the at least two kinds of abrasive grains having different hardnesses are (a) metal oxide and (b) organic polymer particles. The polishing liquid according to claim 1, wherein the at least two kinds of abrasive grains having different hardnesses are abrasive grains selected from the following group A and abrasive grains selected from the group B.
Group A: fumed silica, colloidal silica, synthetic silica, ceria, alumina, titania, zirconia, germania, manganese oxide, and silicon carbide.
Group B: polystyrene and styrene copolymer, (meth) acrylic resin and acrylic copolymer, polyvinyl chloride, polyacetal, saturated polyester, polyamide, polyimide, polycarbonate, phenoxy resin, polyethylene, polypropylene, poly-1-butene Polyolefins and olefin copolymers of poly-4-methyl-1-pentene, phenol resins, urethane resins, urea resins, melamine resins, epoxy resins, and alkyd resins.   The average particle diameter of the high hardness abrasive grains in at least two kinds of abrasive grains having different hardness is 0.01 to 1 μm, and the average particle diameter of the low hardness abrasive grains is the average particle diameter of the high hardness abrasive grains. The polishing liquid according to any one of claims 1 to 4, wherein the polishing liquid is 2 to 50 times.   The concentration of the high hardness abrasive grains is 0.1 to 20% by mass, and the density of the low hardness abrasive grains is 0.1 to 10 times the concentration of the high hardness abrasive grains. The polishing liquid in any one of -5.   Furthermore, an oxidizing agent is contained, The polishing liquid in any one of Claims 1-6 characterized by the above-mentioned.   A chemical mechanical polishing method comprising polishing the polishing liquid according to claim 1 in contact with the surface to be polished and moving the surface to be polished and the polishing surface relative to each other.