JP2006100570A - Polishing composition and polishing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing composition which is suitable for a polishing liquid to be used for chemical mechanical polishing (CMP) in manufacturing a semiconductor device and has a rapid CMP speed and has little occurrence of dishing and can make possible the manufacture of LSIs, and to provide a polishing method using the same. <P>SOLUTION: The polishing composition contains polishing grains, each of which has a different hardness and elastic modulus in a central portion and in a surface portion. The polishing method uses this polishing composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to the manufacture of semiconductor devices, and more particularly to a polishing composition in a wiring process of a semiconductor device and a polishing method using the same.

In the development of semiconductor devices typified by semiconductor integrated circuits (hereinafter referred to as LSIs), in order to achieve higher integration and higher speed, in recent years, higher density and higher integration have been demanded by miniaturization and lamination of wiring. . Chemical mechanical polishing (hereinafter referred to as CMP) has been used as a technique for this purpose. This is used for polishing an insulating thin film (such as SiO ₂ ) and a metal thin film used for wiring, and smoothes the substrate. This is a method of removing an excess metal thin film at the time of forming or wiring, and is disclosed in, for example, Patent Document 1.

A metal polishing solution used in CMP generally contains abrasive grains (for example, alumina) and an oxidizing agent (for example, hydrogen peroxide). The basic mechanism is considered to oxidize the metal surface with an oxidizing agent and remove the oxide film with abrasive grains, and is described in Non-Patent Document 1, for example.
However, when CMP is performed using a polishing composition containing such solid abrasive grains, scratches (scratches), a phenomenon in which the entire polished surface is polished more than necessary (thinning), and a polished metal surface on the dish In some cases, a phenomenon of bending (dishing), a phenomenon in which an insulator between metal wirings is polished more than necessary, and a metal surface of the wiring bends on a plate (erosion) may occur.
In addition, in a cleaning process usually performed to remove the polishing liquid remaining on the semiconductor surface after polishing, the cleaning process becomes complicated by using a polishing liquid containing solid abrasive grains. In order to treat (waste liquid), there is a problem in terms of cost, for example, it is necessary to settle and separate solid abrasive grains.

  As one means for solving these problems, for example, a metal surface polishing method using a combination of a polishing solution not containing abrasive grains and dry etching is disclosed in Non-Patent Document 2, and Patent Document 2 discloses hydrogen peroxide. A polishing composition comprising: / malic acid / benzotriazole / ammonium polyacrylate and water is disclosed. According to these methods, the metal film on the convex portion of the semiconductor substrate is selectively CMPed, and the metal film is left in the concave portion to obtain a desired conductor pattern. Since CMP proceeds by friction with a polishing pad that is much mechanically softer than that containing conventional solid abrasive grains, the occurrence of scratches is reduced.

  On the other hand, tungsten and aluminum have been widely used for interconnect structures as wiring metals. For example, Patent Document 3 and Patent Document 4 describe a polishing liquid and a method for polishing tungsten or aluminum. However, LSIs using copper, which has lower wiring resistance than these metals, have been developed with the aim of achieving higher performance. As a method of wiring this copper, for example, a damascene method described in Patent Document 5 is known. Further, a dual damascene method in which a contact hole and a wiring groove are simultaneously formed in an interlayer insulating film and a metal is embedded in both has been widely used. As a target material for copper wiring, a high-purity copper target of five nines or more has been shipped. However, in recent years, with the miniaturization of wiring aiming at further higher density, it has become necessary to improve the conductivity and electronic characteristics of copper wiring, and accordingly, a copper alloy in which a third component is added to high-purity copper is required. It is also beginning to be considered for use. At the same time, there is a need for high-speed metal polishing means that can exhibit high productivity without contaminating these high-definition and high-purity materials. These copper wirings are more likely to cause scratches called scratches than conventional aluminum wirings. On the other hand, there is a problem that the polishing rate does not increase because of the ductility.

  Recently, in order to improve productivity, the diameter of a wafer at the time of manufacturing an LSI has been increased. Currently, a diameter of 200 mm or more is widely used, and manufacture of a diameter of 300 mm or more has started. With such an increase in size, the difference in polishing rate between the wafer central portion and the peripheral portion has increased, and the demand for improvement in in-plane uniformity has increased.

  Patent Documents 6 to 8 disclose abrasive particles having a coating layer from the viewpoint of improving the polishing rate and suppressing scratches.

US Pat. No. 4,944,836 JP 2001-127019 A JP 11-349926 A Japanese Patent Laid-Open No. 9-22887 JP-A-2-278822 Japanese Patent No. 3509188 JP-A-8-8218 JP 2001-226666 A Journal of Electrochemical Society, 1991, 138, 11, 3460-3464 Journal of Electrochemical Society, 2000, 147, 10, 3907-3913

In the present invention, in order to increase the productivity of LSIs, in order to advance CMP more promptly, it is required to increase the polishing rate in polishing of wiring using such copper metal and copper alloy as a raw material. Based on the above.
Accordingly, an object of the present invention is to provide a polishing composition that has a rapid CMP rate and is less likely to cause dishing and can be used to fabricate LSIs.

  As a result of intensive studies on the problems associated with the above polishing composition, the present inventors have found that the problem can be solved by using the following polishing composition and have achieved the object. That is, the present invention is as follows.

(1) A polishing composition comprising abrasive particles in which at least one of hardness and elastic modulus differs in a central portion and a surface layer portion in one particle.
(2) The polishing composition according to (1), further comprising at least one compound selected from tetrazoles and derivatives thereof or anthranilic acids and derivatives thereof.
(3) The polishing composition as described in (1) or (2) above, wherein the proportion of the abrasive particles is 10% by volume or more based on the total abrasive particles.
(4) The polishing composition according to any one of (1) to (3) is supplied, brought into contact with the surface to be polished, and polished by moving the surface to be polished and the polishing surface relative to each other. Chemical mechanical polishing method.

The polishing composition of the present invention, as a polishing liquid used for chemical mechanical polishing in the production of semiconductor devices and the like, brings about a significant improvement in the chemical mechanical polishing rate, ensuring uniformity in the wafer surface, The occurrence of defects due to local non-uniformity of polishing such as corrosion, scratching, thinning, erosion, etc. is maintained at a low level, and the speed of CMP is high, so that LSI can be manufactured with less dishing. be able to.

Hereinafter, specific embodiments of the present invention will be described.
The polishing composition of the present invention is characterized by containing abrasive particles having at least one of hardness and elastic modulus different from each other in the center portion and the surface layer portion in one particle by modifying the surface as abrasive particles. Yes. Preferably, the ratio of the abrasive particles is 10% by volume or more based on the total abrasive particles.

The polishing composition of the present invention generally contains an oxidizing agent and is usually an aqueous solution.
The polishing composition of the present invention preferably further contains at least one compound selected from tetrazoles and derivatives thereof or anthranilic acids and derivatives thereof. It is also preferable to contain at least one selected from organic acids and amino acids.
The polishing composition of the present invention may further contain other components, and preferable components include surfactants, water-soluble polymers, and additives.
Each component contained in the polishing composition may be used alone or in combination of two or more.

Of the components added during preparation of the concentrate, the blending amount of water having a solubility in water of less than 5% is that water at room temperature is used to prevent precipitation when the concentrate is cooled to 5 ° C or the like. It is preferable that the solubility is within 2 times, more preferably within 1.5 times.
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 composition” 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 composition.

Hereinafter, each component will be described.
[1] Abrasive particles in which at least one of hardness and elastic modulus is different in the central part and surface layer part in one particle by modifying the surface Hardness in the central part and surface layer part in one particle by modifying the surface Abrasive particles having different at least one of the elastic modulus (hereinafter also referred to as abrasive particles of the present invention), for example, when silica is used as the particles, only the surface is carbonized and the surface is hardened, or conversely, the surface There is a method of forming a hydrous silica layer and softening the surface.

In the former method, for example, when silica is mixed with carbon in a high-temperature inert gas atmosphere and only the surface of the silica is reduced, the surface is rich in silicon carbide and the center part is silica. It is. In this way, particles having a structure with a relatively hard surface portion and a soft inside can be obtained.
In the latter method, silica is dispersed in a dilute concentration in a highly alkaline aqueous solvent, and after stirring slowly under high temperature and high pressure, the aqueous solvent is replaced with water, and a soft layer of hydrous silica is formed on the surface layer of silica. Is the method. In this way, particles having a soft structure in the surface layer compared to the inside can be obtained.

Other examples of the abrasive particles include metal oxides and metal nitrides such as aluminum oxide, titanium oxide, tin oxide, cerium oxide, manganese oxide, and chromium oxide.
Other examples of the surface modification method include plasma treatment, mechanofusion method, and etch treatment method.
The particle size of the abrasive particles is preferably 0.01 to 1.2 μm, more preferably 0.02 to 0.6 μm.

The hardness and elastic modulus at the center part and the surface layer part of the abrasive particles can be measured by the following methods.
The change of the elastic force with respect to the depth direction was measured by attaching the particle to the tip of the nanoindenter probe and reading the displacement of the particle with respect to the indentation pressure. By measuring the difference in elastic force change in the depth direction with respect to the particles before and after altering the surface layer, the difference in elastic force between the inside and the outside can be measured. In addition, a crushing test can be performed using an ultra-small compression tester, and the hardness of the particles before and after the alteration can be measured by relative evaluation with other particles.

The hardness of the center portion and the surface layer portion of the abrasive particles is preferably different from the hardness of the center portion by 20% or more, more preferably 30 to 80% or more.
The elastic modulus of the center part and the surface layer part of the abrasive particles is preferably different from that of the central part by 30% or more, more preferably by 40 to 70% or more.
In the evaluation of relative hardness with other particles, in particular, particles with a Mohs hardness of 3.5 to 4.5 on the surface of the particle after modification are resistant to dishing, whereas the Mohs hardness of the particle before modification is 6 to 9 Good performance.

The polishing composition containing the abrasive particles of the present invention has a structure having an inflection point in the polishing force on the surface to be polished depending on the pressure received from the tool or the polishing pad. In particular, particles having a structure with a higher hardness (or higher elasticity) at the center than at the surface have a higher polishing rate during polishing on the high-pressure side. The polishing speed is high at the part where the applied pressure is high, but the polishing speed is suppressed at the part where the processing pressure is relatively low, such as the concave part, and this feature can quickly eliminate the step due to the unevenness of the metal wiring layer. ,preferable.
Furthermore, the abrasive particles of the present invention can effectively prevent so-called dishing due to overpolishing. That is, when the excess metal wiring on the substrate is removed by CMP, the abrasive particles of the present invention having a structure having an inflection point in the polishing force on the surface to be polished depending on the processing pressure This is because the wiring portion that becomes lower than the barrier layer due to overpolishing hardly gives a polishing action.

  Although other abrasive particles as described later may be used in combination, the proportion of the abrasive particles of the present invention is preferably 10% by volume or more based on the total abrasive particles in the polishing composition, and 40 to 100 Volume% is more preferable, and 70 to 100 volume% is still more preferable.

  Examples of other abrasive particles that may be used in combination with the abrasive particles of the present invention include commonly used abrasive grains such as silica (precipitated silica, fumed silica, colloidal silica, synthetic silica). , Ceria, alumina, titania, zirconia, germania, manganese oxide, silicon carbide, polystyrene, polyacryl, polyterephthalate and the like. The average grain size of the abrasive grains is preferably 5 to 1000 nm, particularly preferably 10 to 200 nm.

The total amount of abrasive particles including the abrasive particles of the present invention and other abrasive particles is generally 0.01 to 50% by mass with respect to the total mass of the polishing composition when used, and 0.01 It is preferable that it is -20 mass%, and it is more preferable that it is the range of 0.05-5 mass%. In order to obtain a sufficient effect on the polishing rate, 0.01% by mass or more is preferable. Since the polishing rate by CMP is saturated, 20% by mass or less is preferable.

  The polishing composition preferably contains at least one compound selected from tetrazoles and derivatives thereof or anthranilic acids and derivatives thereof.

  The tetrazole and its derivative are preferably a compound represented by the formula (I), and the anthranilic acid and its derivative are preferably a compound represented by the 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 the description of the group (atomic group) in this specification, the notation 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.

Furthermore, examples include salts obtained by substituting the hydrogen atom of the carboxy group in the above exemplified compounds with alkali metal ions such as Na ⁺ , K ⁺ and Li ^+, and ammonium ions such as NH ₄ ⁺ and quaternary ammonium ions. .

  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 can be synthesized according to the method described in 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 tetrazole and its derivatives or anthranilic acids and its derivatives is the polishing composition used for polishing (ie, the diluted polishing composition when diluted with water or an aqueous solution. In 1 liter of “a polishing composition for use in polishing” is preferably 0.0001 to 1.0 mol, more preferably 0.001 to 0.5 mol, and still more preferably 0.01 to 1.0 mol. 0.1 mol. That is, the amount of tetrazole and its derivative or anthranilic acid and its derivative added is preferably 1.0 mol or less in 1 L of the polishing composition from the viewpoint of preventing deterioration (ineffective, decomposition) of the oxidizing agent and these compounds. In order to obtain a good effect, 0.0001 mol or more is preferable.
The thiocyanate, thioether, thiosulfate, or mesoionic compound may be used in combination in an amount less than the amount of tetrazole and its derivatives or anthranilic acid and its derivatives.

(Oxidant)
The polishing composition of the present invention contains a compound (oxidant) that can oxidize a 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.
Aminopolycarboxylic acids and their salts 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-hydroxybenzyl) ethylenediamine-N, N-divine Like and salts thereof. The kind of the counter salt is preferably an alkali metal salt or an ammonium salt, and particularly preferably an ammonium salt.

Among 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 diacetate, 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 composition when used for polishing. It is particularly preferable to do this. 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, in that range, inorganic acids, organic acids, and amino acids.
Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid, etc. Among the inorganic acids, phosphoric acid is preferable.
In the present invention, organic acids and amino acids are particularly preferably present, and amino acids are more preferable.
The organic acid is preferably water-soluble. Those selected from the following group are more suitable. Formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid , N-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, Examples thereof include tartaric acid, citric acid, lactic acid, 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.
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-cysteic acid, L-aspartic acid, L-glutamic acid, S- (carboxy Methyl) -L-cysteine, 4-aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-quinurenin, L- Amino acids such as histidine, 1-methyl-L-histidine, 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 amount of the acid added is preferably 0.0005 to 0.5 mol, more preferably 0.005 mol to 0.3 mol, in 1 L of the polishing composition used for polishing, and 0.01 mol It is especially preferable to set it to -0.1 mol. That is, the amount of acid added is preferably 0.5 mol or less from the viewpoint of suppressing etching, and 0.0005 mol or more is preferable for obtaining a sufficient effect.

(Chelating agent)
The polishing composition 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-hydroxy Njiru) 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 in 1 L of the polishing composition when used for polishing 0.07 mol is added.

〔Additive〕
Moreover, it is preferable to use the following additives for the polishing composition 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 Azoles such as -1-methyl) -N- (1,2,4-triazolyl-1-methyl) -2-ethylhexylamine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid A mercaptan such as nonyl mercaptan, dodecyl mercaptan, triazine thiol, triazine dithiol, triazine trithiol, and others, and quinaldic acid. Among these, chitosan, ethylenediaminetetraacetic acid, L-tryptophan, cuperazone, triazinedithiol, benzotriazole, 4-hydroxybenzotriazole, 4-carboxyl-1H-benzotriazole butyl ester, tolyltriazole, naphthotriazole have high CMP rate and low etching It is preferable for achieving both speeds.

  The addition amount of these additives is preferably 0.0001 mol to 0.5 mol, more preferably 0.001 mol to 0.2 mol, in 1 L of the polishing composition used for polishing. It is especially preferable to set it as 005 mol-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 composition 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 addition amount of the surfactant and / or hydrophilic polymer is preferably 0.001 to 10 g, and preferably 0.01 to 5 g in 1 L of the polishing composition when used for polishing as a total amount. Is more 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 salt, 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 alkali agent and the buffer may be an amount that maintains the pH within a preferable range, and may be 0.0001 mol to 1.0 mol in 1 L of the polishing composition when used for polishing. Preferably it is 0.003 mol-0.5 mol.
2-14 are preferable, as for pH of the polishing composition at the time of using for grinding | polishing, 3-12 are more preferable, and 3.5-8 are the most preferable. In this range, the polishing composition of the present invention exhibits particularly excellent effects.

  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 and pH.

[Raw metal 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 an LSI, and more preferably a wiring made of a copper alloy. 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 preferably 10% by mass or less, more preferably 1% by mass or less, and most preferably in the range of 0.0001 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 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 in which the semiconductor is made of copper metal and / or a copper alloy 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 composition is a concentrated liquid, and when used, dilutes it with water to use it, or mixes each component in the form of an aqueous solution described in the next section, and adds water if necessary. In some cases, it is used as a working solution after dilution. The polishing method using the polishing composition of the present invention can be applied to any case, and the polishing liquid is supplied to the polishing pad on the polishing surface plate and brought into contact with the surface to be polished to thereby connect the surface to be polished and the polishing pad. This is a polishing method in which polishing is performed by relative movement.
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, the polishing composition 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 a component obtained by adding up the components contained in the aqueous solution and the components of the polishing composition to be diluted is polished. It becomes a component at the time of grind | polishing using the composition for water. 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 composition can be prepared.

  As a method for diluting a concentrated polishing composition by adding water or an aqueous solution, a pipe for supplying the concentrated polishing composition and a pipe for supplying water or an aqueous solution are mixed together and mixed, mixed and diluted. There is a method of supplying the polished polishing composition to the 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 composition 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 and polishing the concentrated polishing composition with water or an aqueous solution, a pipe for supplying the 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. This is a method of polishing while supplying to the polishing pad and mixing by the relative movement of the polishing pad and the surface to be polished. Alternatively, there is a method in which a predetermined amount of a concentrated polishing composition and water or an aqueous solution are mixed in one container, and then the mixed polishing composition is supplied to a polishing pad for polishing.

According to another polishing method of the present invention, a component to be contained in a polishing composition is divided into at least two components, and when these components are used, a water or aqueous solution is added to dilute the polishing pad on a polishing platen. The surface to be polished is brought into contact with the surface to be polished, and the surface to be polished and the polishing pad are moved relative to each other for polishing.
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 relative movement of the polishing pad and the surface to be polished, and the three components are mixed in one container. The diluted polishing composition is supplied 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 solubility becomes high when temperature is high, it is a preferable method for increasing the solubility of raw materials with low solubility of the polishing composition.

  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 composition 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. Further, the polishing composition may be used as a concentrated liquid and supplied to the polishing surface separately from the dilution water.

〔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 composition 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 by way of examples. The present invention is not limited by these examples.

Combustion synthetic silica particles having an average particle size of 0.5 μm (this is referred to as abrasive grains 3) were stirred in a highly alkaline aqueous solvent and highly dispersed by high-pressure dispersion treatment to prepare an aqueous highly dispersed slurry. Further, this was subjected to hydrothermal treatment under high pressure in an autoclave, and then the alkaline aqueous solvent was replaced with water by ultrafiltration treatment to form abrasive grains 1 and 2 having a modified layer of hydrous silicate on the surface layer portion. . The high-pressure hydrothermal treatment time was 20 minutes for the abrasive grains 1 and 3 hours for the abrasive grains 2.
A part of the abrasive grains 1 and 2 was diluted with a large amount of alcohol and then dried to take out the particles. The particles are cut into pieces with FIB (Focused Ion Beam), and the elements contained in the alkaline aqueous solution are mapped with SEM-EDX (scanning electron microscope manufactured by Hitachi High-Technologies Corporation) to alter the surface from the surface to the center. When the reach depth of the layer was determined, when the particle radius was set to 100, it was calculated that the deteriorated layer had spread to an average of 6 for abrasive grains 1 and an average of 35 for abrasive grains 2 (each calculated with 50 grains). It was done.
Moreover, when the particle hardness (crushing hardness) of the abrasive grains 1 to 3 was determined with a micro compression tester (manufactured by Shimadzu Corporation) [measurement conditions: load: 1.4 psi, load speed: 0.048 kgf / min], The abrasive grain 1 was 32 MPa, the abrasive grain 2 was 21 MPa, and the abrasive grain 3 was 35 MPa.

<Example 1>
The polishing liquid shown below was prepared, and the polishing test was conducted and evaluated.
(Preparation of polishing liquid)
Abrasive particles 12g / L
1,2,3-benzotriazole (protective film forming agent) 0.15 g / L
Hydrogen peroxide (oxidant) 9g / L
Glycine (acid) 9g / L
Add pure water, total volume 1000mL
pH (adjusted with aqueous ammonia and sulfuric acid) 6.8

(Polishing test)
Workpiece (base): 8 inch silicon wafer with copper plating film Polishing pad: IC1400 (Rodel Nitta)
Polishing machine: LGP-612 (LapmaSter SFT)
Polishing pressure: 1.2-3.0 psi
Polishing liquid supply rate: 250 ml / min
Number of rotations of workpiece / number of rotations of wafer: 61/59 rpm

(Evaluation methods)
Flatness: Forty-nine points on the wafer before and after polishing were extracted, the thickness of the copper film was converted from the electrical resistance value, and the average polishing rate was determined from the difference. further. The standard deviation of this average polishing rate was determined and defined as flatness (%). It shows that flatness is so favorable that a value is small.
Level difference: The level difference between the wiring part (100 μm) and the space part (100 μm) at the end of planarization was measured with a level difference measuring machine (Dektak P-15 manufactured by Veeco). The smaller the step value is, the better the result is without dishing.

<Examples 2 to 4 and Comparative Example 1>
As in Table 1, the polishing liquids of Examples 2 to 4 and Comparative Example 1 were prepared and subjected to a polishing test in the same manner as in Example 1 except that the abrasive particles and the protective film forming agent were changed.

  From the results of Table 1, it can be seen that Examples 1 to 4 are superior in flatness and have a small level difference, that is, less occurrence of dishing and superior performance as compared with Comparative Example 1.

Claims (4)

  A polishing composition comprising abrasive particles in which at least one of hardness and elastic modulus is different between a central portion and a surface layer portion in one particle.   The polishing composition according to claim 1, further comprising at least one compound selected from tetrazoles and derivatives thereof or anthranilic acids and derivatives thereof.   The polishing composition according to claim 1 or 2, wherein the ratio of the abrasive particles is 10% by volume or more based on the total abrasive particles.   A chemical mechanical polishing comprising: supplying the polishing composition according to any one of claims 1 to 3, bringing the polishing composition into contact with a surface to be polished, and polishing the surface to be polished and the polishing surface by moving relative to each other. Method.