JP2007287832A - Chemical-mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing method which can achieve a high polishing speed and low dishing at a low pressure in chemical-mechanical polishing. <P>SOLUTION: A polishing solution for metals contains (a) at least one kind of organic acid selected among chemical compounds expressed by formula (I), (b) colloidal silica particles, (c) at least one kind of corrosion inhibitor selected from among a group consisting of imidazole compounds and triazole compounds, (d) nonionic surfactant, and (e) hydrogen peroxide, and has a potential etch rate of 20 nm/min or above and a normal etch rate of 5 nm/min or below. In this chemical-mechanical polishing method, when polishing a plane to be polished by a polishing pad at a polishing pressure of 1.0 psi or below while the polishing pad and the plane to be polished are moved relative to each other in a state that they are in contact with each other, with the polishing solution being supplied onto the plane to be polished, the polishing speed is 300 nm/min or above and an average frictional resistance value is 0.5 or below. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polishing method for performing chemical mechanical planarization at the time of polishing a semiconductor device, for example.

In the development of semiconductor devices typified by semiconductor integrated circuits (hereinafter referred to as “LSI”), in recent years, miniaturization and stacking of wiring have required higher density and higher integration in order to reduce the size and increase the speed. ing. For this purpose, various techniques such as chemical mechanical polishing (hereinafter referred to as “CMP”) have been used.
A general method of CMP is to apply a polishing pad on a circular polishing platen (platen), immerse the surface of the polishing pad with a polishing liquid, press the surface of the substrate (wafer) against the pad, In a state where pressure (polishing pressure) is applied, both the polishing platen and the substrate are rotated, and the surface of the substrate is flattened by the generated mechanical friction.
The metal polishing liquid used for CMP generally contains abrasive grains (for example, alumina, silica) and an oxidizing agent (for example, hydrogen peroxide, persulfuric acid). The metal surface is oxidized by the oxidizing agent, and the oxidation is performed. It is considered that the film is polished by removing the film with abrasive grains.

However, when CMP is performed using a metal polishing liquid containing such solid abrasive grains, scratches (scratches), a phenomenon in which the entire polished surface is polished more than necessary (thinning), and the polished metal surface is flat In addition, a phenomenon in which only the center is polished deeper to form a dish-like depression (dishing), an insulator between metal wirings is polished more than necessary, and a plurality of wiring metal surface surfaces form dish-shaped recesses. A phenomenon (erosion) may occur.
In order to solve the problems in such conventional solid abrasive grains, a metal polishing liquid which does not contain abrasive grains and is composed of hydrogen peroxide / malic acid / benzotriazole / ammonium polyacrylate and water is disclosed. (For example, refer to Patent Document 1). According to this method, although 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, it is much more mechanical than the conventional solid abrasive grains. Since CMP proceeds by friction with a soft polishing pad, it is difficult to obtain a sufficient polishing rate.

  On the other hand, tungsten and aluminum have conventionally 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. As a method for wiring this copper, for example, a damascene method described in Patent Document 2 is known. Further, a dual damascene method in which a contact hole and a wiring trench 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.

  Furthermore, as a chemical polishing method having no mechanical polishing means for copper and copper alloys, a method described in Patent Document 3 is known. However, the chemical polishing method using only the chemical dissolution action has a greater problem in flatness due to the occurrence of dishing of the recess, that is, the occurrence of dishing, as compared with CMP in which the metal film of the protrusion is selectively chemically and mechanically polished. Remaining.

  In addition to the above, in recent years, it is desired to perform CMP under a very low pressure condition in order to use a low-k material having low mechanical strength for the insulating film. However, when CMP is performed under a low pressure condition using a conventional slurry, there has been a serious problem that the polishing rate is greatly reduced.

JP 2001-127019 A JP-A-2-278822 JP 49-122432 A

  The present invention was made based on the background of sufficiently high-precision CMP processing under low pressure conditions. Accordingly, an object of the present invention is to provide a polishing method that achieves a high polishing rate and low dishing under low pressure conditions in chemical mechanical polishing of a film to be processed of a semiconductor device or the like.

As a result of intensive studies, the present inventor has found that the above problem can be solved by using the following polishing method, and has achieved the object. That is, the present invention is as follows.
<1> (a) At least one corrosion selected from the group consisting of at least one organic acid selected from the compounds represented by the following formula (I), (b) colloidal silica particles, (c) imidazole compounds and triazole compounds. Inhibitor, (d) Nonionic surfactant, and (e) Hydrogen peroxide, (a) The etching rate when only the organic acid and (e) hydrogen peroxide coexist is 20 (nm / min) or more. And (a) an organic acid, (c) a corrosion inhibitor, (d) a nonionic surfactant, and (e) an etching rate when coexisting with an oxidizing agent is 5 (nm / min) or less. A chemical mechanical polishing method using a polishing pad, wherein a polishing pad pressing pressure (polishing pressure) is 1.0 psi or less while contacting the polishing pad and the surface to be polished while supplying the metal polishing liquid to the surface to be polished. Relative to Chemical mechanical polishing method in which is polished by moving the polishing rate is 300 (nm / min) or more and an average frictional resistance is equal to or more than 0.5,

（式（I）中、Ｒ¹は、単結合、又は、アルキレン基を表し、Ｒ²及びＲ³は、各々独立に、水素原子、アルキル基、アルキニル基、アルケニル基、又は、アリール基を表し、Ｒ⁴は、水素原子、又は、水酸基、アミノ基若しくはカルボキシル基で置換された有機基を表し、また、Ｒ⁵は、アルキル基、又は、水酸基、アミノ基若しくはカルボキシル基で置換された有機基を表す。）
＜２＞ 前記腐食抑制剤が、ベンゾトリアゾール、ベンゾイミダゾール、１，２，３−トリアゾール、１，２，４−トリアゾール、及び、イミダゾールよりなる群から選ばれる化合物である上記＜１＞に記載の化学的機械的研磨方法、
＜３＞ 前記ノニオン性界面活性剤が下記式（II）で表される化合物である上記＜１＞又は＜２＞に記載の化学的機械的研磨方法。

(In Formula (I), R ¹ represents a single bond or an alkylene group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, an alkynyl group, an alkenyl group, or an aryl group. R ⁴ represents a hydrogen atom or an organic group substituted with a hydroxyl group, an amino group or a carboxyl group, and R ⁵ represents an alkyl group or an organic group substituted with a hydroxyl group, an amino group or a carboxyl group. Represents.)
<2> The above-described <1>, wherein the corrosion inhibitor is a compound selected from the group consisting of benzotriazole, benzimidazole, 1,2,3-triazole, 1,2,4-triazole, and imidazole. Chemical mechanical polishing method,
<3> The chemical mechanical polishing method according to <1> or <2>, wherein the nonionic surfactant is a compound represented by the following formula (II).

（式（II）中、Ｒ¹〜Ｒ⁶は、それぞれ独立に水素原子又は炭素数１〜１０のアルキル基を表し、Ｘ及びＹは、それぞれ独立にエチレンオキシ基又はプロピレンオキシ基を表し、また、ｍ及びｎは、それぞれ独立に０〜２０の整数を表す。）

(In formula (II), R ^{1 to} R ⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, X and Y each independently represent an ethyleneoxy group or a propyleneoxy group, , M and n each independently represents an integer of 0 to 20.)

  According to the present invention, it is possible to provide a polishing method capable of performing LSI processing with a high polishing rate and high performance under low pressure conditions in chemical mechanical polishing of a film to be processed of a semiconductor device.

The chemical mechanical polishing method of the present invention comprises (a) at least one organic acid selected from compounds represented by the following formula (I), (b) colloidal silica particles, (c) an imidazole compound and a triazole compound. At least one corrosion inhibitor selected from the group, (d) a nonionic surfactant, and (e) hydrogen peroxide, (a) an etching rate when only an organic acid and (e) hydrogen peroxide coexist ( (Hereinafter also referred to as “latent etching rate”) is 20 (nm / min) or more, (a) an organic acid, (c) a corrosion inhibitor, (d) a nonionic surfactant, (e) an oxidizing agent, Chemical mechanical using a metal polishing liquid (hereinafter also simply referred to as “polishing liquid”) having an etching rate (hereinafter also referred to as “normal etching speed”) of 5 (nm / min) or less. Polishing method Then, while supplying the metal polishing liquid to the surface to be polished, the polishing pad pressing pressure (polishing pressure) is 1.0 psi or less, and the polishing pad and the surface to be polished are brought into contact with each other to perform polishing. The polishing rate is 300 (nm / min) or more and the average frictional resistance value is 0.5 or less.
Hereinafter, specific embodiments of the present invention will be described.

(Metal polishing liquid)
[Organic acid]
The polishing liquid that can be used in the present invention contains at least one organic acid selected from compounds represented by the following formula (I).

（式（I）中、Ｒ¹は、単結合、又は、アルキレン基を表し、Ｒ²及びＲ³は、各々独立に、水素原子、アルキル基、アルキニル基、アルケニル基、又は、アリール基を表し、Ｒ⁴は、水素原子、又は、水酸基、アミノ基若しくはカルボキシル基で置換された有機基を表し、また、Ｒ⁵は、アルキル基、又は、水酸基、アミノ基若しくはカルボキシル基で置換された有機基を表す。）

(In Formula (I), R ¹ represents a single bond or an alkylene group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, an alkynyl group, an alkenyl group, or an aryl group. R ⁴ represents a hydrogen atom or an organic group substituted with a hydroxyl group, an amino group or a carboxyl group, and R ⁵ represents an alkyl group or an organic group substituted with a hydroxyl group, an amino group or a carboxyl group. Represents.)

  In addition, in the description of substituents (atomic groups) in the compounds in this specification, when neither substituted nor unsubstituted is described, it includes those having no substituent and those having 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).

The alkylene group as R ¹ in the formula (I) may be linear, branched or cyclic, and preferably has 1 to 8 carbon atoms, and examples thereof include a methylene group and an ethylene group. it can.
Examples of the substituent that the alkylene group may have include a hydroxyl group and a halogen atom.

When R < ² > and R < ³ > represent an alkyl group, Preferably it is a C1-C8 alkyl group, for example, a methyl group, a propyl group, etc. can be mentioned.
The cycloalkyl group as R ² and R ³ preferably has 5 to 15 carbon atoms, and examples thereof include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. The alkenyl group as R ² and R ³ preferably has 2 to 9 carbon atoms, and examples thereof include a vinyl group, a propenyl group, and an allyl group. The alkynyl group as R ² and R ³ preferably has 2 to 9 carbon atoms, and examples thereof include an ethynyl group, a propynyl group, and a butynyl group.

The aryl group as R ² and R ³ preferably has 6 to 15 carbon atoms, and examples thereof include a phenyl group.
The alkylene chain in these groups may have a hetero atom such as an oxygen atom or a sulfur atom. Examples of the substituent that each functional group as R ² and R ³ may have include a hydroxyl group, a halogen atom, and an aromatic ring (preferably having 3 to 15 carbon atoms).

The organic group substituted with a hydroxyl group, amino group or carboxyl group as R ⁴ and R ⁵ may be an organic group substituted with one or more hydroxyl groups, amino groups or carboxyl groups. Preferred examples of the organic group include an alkyl group, an alkenyl group, an alkynyl group, an alkylene oxide group, and an acyl group. Among them, an alkyl group, an alkylene oxide group, and an acyl group are more preferable. These groups may be linear or have a branched or ring structure, and as a substituent other than a hydroxyl group, an amino group or a carboxyl group, a hydroxyl group, a halogen atom, an aromatic ring (heteroaromatic) It may also contain a ring, and preferably has 3 to 15 carbon atoms.
Specific examples of the organic group substituted with a hydroxyl group, an amino group or a carboxyl group include —CH ₂ OH, —CH ₂ CH ₂ OH, — (CH ₂ CH ₂ O) ₂ H, —COCH ₂ NH ₂ , —CH. ₂ CH ₂ COOH can be preferably exemplified.

The alkyl group as R ⁵ preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and an ethyl group.
Examples of the substituent that each organic group as R ⁴ and R ⁵ may have include a hydroxyl group, an amino group, and a carboxyl group.

  Specific examples of the compound represented by formula (I) are shown below, but the present invention is not limited thereto. In the following specific examples, “-Ph” represents a phenyl group.

  The compound represented by the formula (I) can be synthesized by a known method, but a commercially available product may be used. The total amount of the compound represented by the formula (I) is preferably 0.0005 to 5 mol, more preferably 0.01 to 0.5 mol in 1 L of the metal polishing liquid used for polishing. is there.

[Abrasive particles]
The polishing liquid used in the present invention contains at least colloidal silica particles as a constituent component.

Examples of the method for producing the colloidal silica particles include silicon such as Si (OC ₂ H ₅ ) ₄ , Si (sec-OC ₄ H ₉ ) ₄ , Si (OCH ₃ ) ₄ , and Si (OC ₄ H ₉ ) _4. It can be obtained by hydrolyzing an alkoxide compound by a sol-gel method. Such colloidal silica particles have a very sharp particle size distribution.

  The average particle size of the colloidal silica particles is a particle size cumulative curve showing the relationship between the particle size of the colloidal silica particles and the cumulative frequency obtained by integrating the number of particles having the particle size, and the cumulative frequency of this curve is the point where the cumulative frequency is 50%. This means the particle diameter at. The particle diameter of the colloidal particles represents an average particle diameter determined in the particle size distribution obtained from the dynamic light scattering method. For example, LB-500 manufactured by HORIBA, Ltd. is used as a measuring device for obtaining the particle size distribution.

  The average particle diameter of the colloidal silica particles contained is preferably 5 to 60 nm, more preferably 5 to 30 nm. Particles of 5 nm or more are preferable for the purpose of achieving a sufficient polishing speed. The particle diameter is preferably 60 nm or less for the purpose of preventing excessive frictional heat during polishing.

  The concentration of the abrasive particles composed of the contained composite is preferably contained in the polishing liquid in a proportion of 0.001 to 1% by weight. More preferably, 0.01 to 1% by weight is desirable. In order to achieve a sufficient polishing speed, the concentration is preferably 0.001% by weight or more. The concentration is preferably 1% by weight or less for the purpose of achieving high planarization performance.

(Corrosion inhibitor)
The polishing liquid used in the present invention contains at least one imidazole compound and / or triazole compound as a compound that forms a passive film on the metal surface to be polished and suppresses a chemical reaction on the substrate.

  Corrosion inhibitors that can be used in the present invention include benzotriazole, benzimidazole, 1,2,3-triazole, 1,2,4-triazole, imidazole, benzimidazole-2-thiol, and 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-benzo Riazolyl-1-methyl) -N- (1,2,4-triazolyl-1-methyl) -2-ethylhexylamine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid are preferred It can be illustrated. Among these, it is particularly preferable to use benzotriazole, benzimidazole, 1,2,3-triazole, 1,2,4-triazole, or imidazole.

  The corrosion inhibitor that can be used in the present invention may be used alone or in combination of two or more. Moreover, the corrosion inhibitor that can be used in the present invention can be synthesized according to a conventional method, or a commercially available product may be used.

  The addition amount of the corrosion inhibitor that can be used in the present invention is, as a total amount, in 1 L of a metal polishing liquid used for polishing (that is, a metal polishing liquid after dilution when diluted with water or an aqueous solution). 0.0001 to 1.0 mol is preferable, 0.0005 to 0.5 mol is more preferable, and 0.0005 to 0.05 mol is still more preferable.

[Nonionic surfactant]
The polishing liquid that can be used in the present invention contains a nonionic surfactant represented by the formula (II).

（式（II）中、Ｒ¹〜Ｒ⁶は、それぞれ独立に水素原子又は炭素数１〜１０のアルキル基を表し、Ｘ及びＹは、それぞれ独立にエチレンオキシ基又はプロピレンオキシ基を表し、また、ｍ及びｎは、それぞれ独立に０〜２０の整数を表す。）

(In formula (II), R ^{1 to} R ⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, X and Y each independently represent an ethyleneoxy group or a propyleneoxy group, , M and n each independently represents an integer of 0 to 20.)

In formula (II), R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group or an isopropyl group. And more preferably a hydrogen atom.
In formula (II), R ^{3 to} R ⁶ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and are a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, or 2-methylpropyl. It is preferably a group, more preferably a methyl group or a 2-methylpropyl group.
In formula (II), X and Y are each independently an ethyleneoxy group (—CH ₂ CH ₂ O—) or a propyleneoxy group (—CH ₂ CH ₂ CH ₂ O—, —CH ₂ CH (CH ₃ ). O— or —CH (CH ₃ ) CH ₂ O—), and —CH ₂ CH ₂ O—, —CH ₂ CH (CH ₃ ) O— or —CH (CH ₃ ) CH ₂ O—. More preferred is —CH ₂ CH ₂ O—. It is also preferable that m or n corresponding to 0 is 0 as described later, and X and Y are each independently a single bond.
Moreover, when X and / or Y is a propyleneoxy group and the corresponding m or n is 2 or more, the propyleneoxy structure may be mixed. In addition, the ethyleneoxy group and propyleneoxy group in X or Y shall combine with R < ¹ > O- or R < ² > O- with a carbon atom.
In formula (II), m and n are each independently an integer of 0 to 20.
In the formula (II), when m and / or n is 0, the corresponding X and / or Y is a single bond.

  Preferred examples of the nonionic surfactant include the following structures. In addition, m and n in the following W-2 represent the integers of arbitrary 1-20 each independently.

The nonionic surfactant can be synthesized by a known method, but a commercially available product may be used.
The total amount of the compound represented by the formula (II) is preferably 0.01 to 5% by weight, more preferably 0.05 to 3% by weight in the metal polishing liquid when used for polishing. It is. When the addition amount is in the above range, it is preferable because a sufficient effect is exhibited and good storage stability can be achieved.

〔hydrogen peroxide〕
The polishing liquid that can be used in the present invention contains hydrogen peroxide as an oxidizing agent.

  The amount of hydrogen peroxide added is preferably 0.003 mol to 8 mol, more preferably 0.03 mol to 6 mol, more preferably 0.1 mol to 4 mol, per liter of the metal polishing liquid used for polishing. It is particularly preferable that That is, the amount of hydrogen peroxide added is preferably 0.003 mol or more from the viewpoint of sufficient metal oxidation and ensuring a high CMP rate, and preferably 8 mol or less from the viewpoint of preventing roughening of the polished surface.

[Etching rate]
The polishing liquid that can be used in the present invention has an etching rate (latent etching rate) of 20 (nm / min) when only at least one organic acid selected from the compound represented by formula (I) and hydrogen peroxide coexist. It is the above, and at least one kind of organic acid selected from the compounds represented by formula (I), one kind of corrosion inhibitor selected from imidazole compounds and triazole compounds, a nonionic surfactant and hydrogen peroxide at the time of coexistence The etching rate (normal etching rate) is 0 to 5 (nm / min). Here, it is preferable that the latent etching rate is 20 (nm / min) or more because it has a sufficient polishing rate. Further, the normal etching rate is 0 to 5 (nm / min) and preferably 0 to 1 (nm / min) in order to achieve high planarization.

  The etching rate described here is defined as a value obtained by immersing an object to be polished in an aqueous solution in which an organic acid or the like is dissolved at room temperature, and dividing a change in film thickness of the object to be polished before and after immersion by an immersion time.

  Up to now, there has been a serious problem that the planarization performance is significantly impaired when the chemical action (etching rate) is increased. Unlike the conventional polishing liquid (slurry), the reason why the amount of the polishing liquid used can be reduced in the present invention is considered to be due to the use of a nonionic surfactant. That is, the nonionic surfactant is adsorbed on the passive film formed on the metal surface, and forms a thick suppression film on the metal surface to strongly suppress etching. In this state, since the chemical action does not work, the polishing rate becomes slow. However, at the moment when the adsorbed film is removed by the abrasive particles (when there is no film to suppress), high polishing rate is achieved while maintaining the planarization performance due to the characteristics of the polishing liquid that effectively advances the etching. I was able to do it. More specifically, the etching rate when organic acids, corrosion inhibitors, nonionic surfactants and oxidizing agents coexist (normally defined as etching rate), and the etching rate when only organic acids and oxidizing agents coexist (latent etching rates). By increasing the difference from the definition, it is possible to achieve a high polishing rate and a high leveling performance.

[Dispersion medium]
As a dispersion medium for polishing liquid that can be used in the present invention, water alone or water as a main component (in the dispersion medium, 50 to 99% by weight) and a water-soluble organic solvent such as alcohol or glycol as subcomponents (1 (About 30% by weight) 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 preferably 75 to 95% by weight, and more preferably 85 to 90% by weight. 75 weight% or more is preferable from a viewpoint of the supply property to the board | substrate of polishing liquid.

(acid)
The polishing liquid of the present invention may further contain an acid other than the compound represented by formula (I). The acid here has the action of promoting oxidation, adjusting pH, and buffering agent. Examples of the acid include inorganic acids and organic acids other than the compound represented by the formula (I) within the 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.
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, glycolic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, malic acid, tartaric acid, citric acid, lactic acid, glycine , Iminodiacetic acid, and salts thereof such as ammonium salts and alkali metal salts, sulfuric acid, nitric acid, ammonia, ammonium salts, or a mixture thereof. Among these, formic acid, malonic acid, malic acid, tartaric acid, citric acid, glycine, iminodiacetic acid for a laminated film including at least one metal layer selected from copper, copper alloys and copper or copper alloy oxides It is preferable.

  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.

In the polishing liquid that can be used in the present invention, 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 the liquid Depending on the nature, compound types, addition amounts, pH adjusters, etc. may be added in a timely manner.
Moreover, 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.

(Chemical mechanical polishing method)
The chemical mechanical polishing method of the present invention is selected from (a) at least one organic acid selected from the compounds represented by formula (I), (b) colloidal silica particles, (c) imidazole compounds and triazole compounds. A type of corrosion inhibitor, (d) a nonionic surfactant, and (e) hydrogen peroxide, and (a) an etching rate when only an organic acid and (e) hydrogen peroxide coexist is 20 (nm / min) A metal having an etching rate of 5 (nm / min) or less when (a) an organic acid, (c) a corrosion inhibitor, (d) a nonionic surfactant, and (e) an oxidant coexist. A chemical mechanical polishing method using a polishing slurry, wherein the polishing pad pressing surface (polishing pressure) is 1.0 psi or less while supplying the metal polishing slurry to the surface to be polished. Relative motion while touching When polishing is performed, polishing is performed at a polishing rate of 300 (nm / min) or more and an average frictional resistance value of 0.5 or less.

Here, the average frictional resistance value is defined as a value obtained by dividing the frictional force between the surface to be polished and the polishing cloth during polishing (force in the direction of the rotating linear velocity in this case) by the pressing pressure.
In the present invention, 1 psi = 6.889476 × 10 ³ Pa.

A polishing apparatus generally has a polishing platen with a holder for holding an object to be polished such as a semiconductor substrate having a surface to be polished, and a polishing pad attached (a motor capable of changing the number of rotations is attached). A simple polishing apparatus 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 0.3 to 1 psi, and the in-plane uniformity of the object to be polished (wafer) and the flatness of the pattern at the polishing rate Is more preferably 0.5 to 1 psi.
The polishing rate of the chemical mechanical polishing method of the present invention is 300 nm / min or more, preferably 400 m / min or more, and more preferably 600 nm / min or more. The above range is preferable because a high polishing rate and high planarization performance can be achieved.
The average frictional resistance value is 0.5 or less, preferably 0.45 or less, and more preferably 0.4 or less. The above range is preferable because high flattening can be achieved because the temperature does not increase excessively and scratches can be reduced.

[Raw metal materials]
In the present invention, the object to be polished (target to be polished) is preferably a wiring made of copper metal and / or a copper alloy in a semiconductor such as LSI, and particularly preferably a copper alloy. Furthermore, the copper alloy containing silver is preferable among copper alloys. In the copper alloy, the silver content contained in the copper alloy is preferably 40% by weight or less, more preferably 10% by weight or less, further preferably 1% by weight or less, and in the range of 0.00001 to 0.1% by weight. The most excellent effect is demonstrated. As described above, the metal polishing liquid that can be used in the present invention is a polishing liquid that can be suitably used for polishing metal wiring in a semiconductor such as an LSI. It goes without saying that the silicon substrate, silicon oxide, silicon nitride, resin, carbon wiring, noble metal wiring, barrier layer, insulating film, etc. may be partially polished by the effect of acid, abrasive grains, or the like.

[Wiring thickness]
The semiconductor to which the polishing method of the present invention can be applied is, for example, an LSI having a wiring of 0.15 μm or less at a half pitch in a DRAM device system, more preferably 0.10 μm or less, and 0.08 μm. More preferably, it is as follows. On the other hand, in the MPU device system, an LSI having a wiring of 0.12 μm or less is preferable, 0.09 μm or less is more preferable, and 0.07 μm or less is more preferable. For these DRAMs or LSIs, the chemical mechanical polishing method of the present invention exhibits particularly excellent effects.

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

〔pad〕
The polishing pad for polishing 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 wafer as the object to be polished to be subjected to CMP with the polishing liquid that can be used in the present invention preferably has a diameter of 200 mm or more, and particularly preferably 300 mm or more. The effect of the present invention is remarkably exhibited when the thickness is 300 mm or more.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to them.

<Example 1>
The following polishing liquid was prepared and evaluated for polishing.

(Preparation of polishing liquid)
The following composition was mixed to prepare a polishing liquid.
A-1 (organic acid) 20 g / L
Colloidal silica particles (PL-3H) 1g / L
Hydrogen peroxide (oxidant) 10g / L
Benzimidazole (corrosion inhibitor) 0.1g / L
Surfynol 104E (nonionic surfactant, manufactured by Nissin Chemical Industry Co., Ltd.)
1g / L
Add pure water to make a total of 1,000mL
pH (adjusted with aqueous ammonia and sulfuric acid) 7.0

(Evaluation methods)
Using "MA-300D" manufactured by Musashino Electronics Co., Ltd. as the polishing device, while supplying the slurry onto the polishing cloth of the polishing surface plate of the polishing apparatus, the polishing platen and the substrate were relative to each other while pressed against the polishing cloth. To polish the metal film, and the polishing rate at that time was measured.
Substrate: Silicon wafer with copper film cut into 6 x 6 cm Table rotation speed: 112 rpm
Head rotation speed: 113 rpm (processing linear velocity = 1.0 m / s)
Polishing pressure: 1 psi
Polishing pad: Product number IC-1400 (K-grv) + (A21) manufactured by Rohm and Haas
Slurry supply rate: 50 ml / min

1) <Normal etching rate>
A silicon wafer with a copper film cut to 2 × 4 cm is immersed for 1 minute in an aqueous solution in which organic acids, corrosion inhibitors, surfactants, and oxidizing agents are dissolved in each example and comparative example, and etching is performed from the change in film thickness before and after immersion. The speed was calculated.
Formula: Normal etching rate (nm / min) = (thickness of copper film before immersion−thickness of copper film after immersion) / polishing time 2) <latent etching rate>
A silicon wafer with a copper film cut into 2 × 4 cm was immersed for 1 minute in an aqueous solution in which only an organic acid and an oxidizing agent in each Example and Comparative Example were dissolved, and the etching rate was calculated from the change in film thickness before and after immersion.
Formula: latent etching rate (nm / min) = (thickness of copper film before dipping−thickness of copper film after dipping) / polishing time 3) <polishing rate>
The polishing rate was derived from the following equation by converting the film thickness before and after polishing from electrical resistance.
It was measured by the formula: polishing rate (nm / min) = (thickness of copper film before polishing−thickness of copper film after polishing) / polishing time.
4) <Dishing evaluation>
The pattern wafer is polished for a time corresponding to 50% of the time in addition to the time until the copper in the non-wiring portion is completely polished, and the dishing of the line and space portion (line 100 μm, space 100 μm) is touched. Measurement was performed with a needle-type step gauge Dektak V320Si (Veeco).
5) <Average frictional resistance value>
The frictional force in the direction of the rotational linear velocity during polishing in each example was determined, and the average frictional resistance value was calculated from the following equation.
Formula: Average frictional resistance value (COF) = Friction resistance in the linear velocity direction during polishing / Polishing pressure

<Examples 2 to 27, Comparative Examples 1 and 2>
Except for the components and conditions described in Tables 1 to 3, the polishing tests of Examples 2 to 27 and Comparative Examples 1 and 2 were performed according to the same polishing liquid and polishing conditions as in Example 1. The results are shown in Tables 1-3.

Claims (3)

(A) at least one organic acid selected from compounds represented by the following formula (I):
(B) colloidal silica particles,
(C) at least one corrosion inhibitor selected from the group consisting of imidazole compounds and triazole compounds,
(D) a nonionic surfactant, and
(E) contains hydrogen peroxide,
(A) The etching rate when only an organic acid and (e) hydrogen peroxide coexist is 20 (nm / min) or more, (a) an organic acid, (c) a corrosion inhibitor, and (d) a nonionic surfactant. And (e) a chemical mechanical polishing method using a metal polishing liquid having an etching rate of 5 (nm / min) or less when coexisting with an oxidizing agent,
When the polishing liquid is supplied to the surface to be polished and the polishing pad is pressed by a relative pressure (polishing pressure) of 1.0 psi or less and the polishing pad and the surface to be polished are in contact with each other and polished. And a polishing rate of 300 (nm / min) or more and an average frictional resistance value of 0.5 or less.

(In Formula (I), R ¹ represents a single bond or an alkylene group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, an alkynyl group, an alkenyl group, or an aryl group. R ⁴ represents a hydrogen atom or an organic group substituted with a hydroxyl group, an amino group or a carboxyl group, and R ⁵ represents an alkyl group or an organic group substituted with a hydroxyl group, an amino group or a carboxyl group. Represents.)   The chemical mechanical compound according to claim 1, wherein the corrosion inhibitor is a compound selected from the group consisting of benzotriazole, benzimidazole, 1,2,3-triazole, 1,2,4-triazole, and imidazole. Polishing method. The chemical mechanical polishing method according to claim 1 or 2, wherein the nonionic surfactant is a compound represented by the following formula (II).

(In formula (II), R ^{1 to} R ⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, X and Y each independently represent an ethyleneoxy group or a propyleneoxy group, , M and n each independently represents an integer of 0 to 20.)