JP2007194335A - Chemical mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing method capable of suppressing surface defect including scratches, and sufficiently suppressing a cost in practical usage in a planarizing process of a surface to be polished by the chemical mechanical polishing method. <P>SOLUTION: In the chemical mechanical polishing method, polishing is executed by relatively moving a polishing pad by relatively moving the polishing pad in a state where the polishing pad contacts a surface to be polished, while supplying a polishing liquid containing 7-hydroxy-5-methyl-1, 3, 4-triazaindolizine, coloidal silica as a polishing particle, an organic acid represented by a formula (1), and a corrosion inhibitor to the polishing pad on a polishing plate at a flow rate of 0.035-0.25 ml/(min×cm<SP>2</SP>) per unit area of a semiconductor substrate and per time unit. In the formula, R<SP>1</SP>and R<SP>2</SP>each independently denote hydrogen atom, alkyl group, phenyl group, carboxyl radical, hydroxyl group or organic group substituted by amino group. A reference numeral n denotes 0 or 1. <P>COPYRIGHT: (C)2007,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 represented by large-scale integrated circuits (hereinafter referred to as “LSI”), in recent years, miniaturization and stacking of wiring has led to higher density and higher integration for miniaturization and higher speed. It has been demanded. 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 (slurry), press the surface of the substrate (wafer) against the pad, and backside thereof. In a state where a predetermined 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. Such a chemical mechanical polishing method is applied to formation of capacitors, gate electrodes, etc. in addition to wiring formation, and is also used for mirror polishing of silicon wafers such as SOI (Silicon on Insulator) substrates. Has been. As described above, the objects to be polished by the chemical mechanical polishing method are diverse, such as a polysilicon film (polycrystalline silicon film), a single crystal silicon film, a silicon oxide film, aluminum, tungsten, and copper.

However, when CMP is performed, a polishing scratch (scratch), a phenomenon in which the entire polishing surface is polished more than necessary (thinning), and the polishing surface is not flat, but only the center is deeply polished, resulting in a dish-shaped depression. In some cases, a phenomenon (dishing), an insulator between wirings is polished more than necessary, and a plurality of wiring metal surface surfaces form dish-shaped recesses (erosion).
On the other hand, attention has been focused on lowering the dielectric constant of interlayer insulating films for the purpose of improving the performance of VLSI. As a substitute for the SiO ₂ film having a high dielectric constant, silsesquioxane (dielectric constant: about 2.6 to 3.0), fluorine-added SiO ₂ (dielectric constant: about 3.3) can be used to reduce the dielectric constant. To 3.5), polyimide resin (dielectric constant: about 2.4 to 3.6, manufactured by Hitachi Chemical Co., Ltd., trade name "PIQ", Allied Signal, trade name "FLARE", etc.), benzocyclo Butene (dielectric constant: about 2.7, manufactured by Dow Chemical, trade name “BCB”, etc.), hydrogen-containing SOG (dielectric constant: about 2.5 to 3.5) and organic SOG (dielectric constant: about 2.9) An interlayer insulating film made of Hitachi Chemical Co., Ltd., trade name “HSGR7” and the like has been developed. However, these insulating films have lower mechanical strength than the SiO ₂ film, and are soft and brittle, so that the conventional slurry sometimes generates large scratches.

  Various compositions have been proposed for chemical mechanical polishing aqueous dispersions that suppress surface defects such as scratches. For example, it is disclosed that a slurry containing 7-hydroxy-5-methyl-1,3,4-triazaindolizine is excellent in surface smoothness (see, for example, Patent Document 1).

JP 2001-269859 A

However, the polishing liquid described in Patent Document 1 has not been sufficiently examined for other components constituting the polishing liquid. In addition, in using 7-hydroxy-5-methyl-1,3,4-triazaindolizine, a factor that increases the cost is also inherent.
The present invention relates to a chemical mechanical polishing method in which surface defects such as scratches can be suppressed in the planarization process of the surface to be polished by the chemical mechanical polishing method, and the cost can be sufficiently suppressed even in actual use. The purpose is to provide. The chemical mechanical polishing method of the present invention can be particularly suitably used for the production of semiconductor devices.

As a result of intensive studies, the present inventor has found that the above problem can be solved by the means described in <1>, and has solved the problem. It is described below together with <2> and <3> which are preferred embodiments.
<1> A polishing liquid containing 7-hydroxy-5-methyl-1,3,4-triazaindolizine, colloidal silica as an abrasive particle, an organic acid represented by formula (1), and a corrosion inhibitor. A semiconductor substrate is supplied to a polishing pad on a polishing surface plate at a flow rate of 0.035 to 0.25 ml / (min · cm ² ) per unit area and unit time, and the polishing pad and the surface to be polished are in contact with each other. A chemical mechanical polishing method characterized by moving and polishing;

式中、Ｒ¹及びＲ²は、各々独立に、水素原子、アルキル基、フェニル基、カルボキシル基、水酸基又はアミノ基を置換した有機基を表す。ｎは０又は１を表す。

In the formula, R ¹ and R ² each independently represents a hydrogen atom, an alkyl group, a phenyl group, a carboxyl group, a hydroxyl group, or an organic group substituted with an amino group. n represents 0 or 1.

<2> The chemical mechanical polishing method according to <1>, wherein the organic acid represented by the formula (1) is selected from the group consisting of malic acid, tartaric acid, citric acid and derivatives thereof,
<3> The chemical mechanical polishing method according to <1> or <2>, wherein the corrosion inhibitor includes benzotriazole or a derivative thereof.

  According to the present invention, in a chemical mechanical polishing method for a film to be processed of a semiconductor device, a sufficient polishing rate can be achieved with a small amount of polishing liquid used, and surface defects such as scratches can be suppressed. Thus, it is possible to provide a chemical mechanical polishing method capable of sufficiently reducing the cost even in the use of the above.

Hereinafter, specific embodiments of the present invention will be described.
In addition, in the description of group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what has a substituent with what 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).

[Chemical mechanical polishing method]
The chemical mechanical polishing method of the present invention (hereinafter also simply referred to as “polishing method”) comprises 7-hydroxy-5-methyl-1,3,4-triazaindolizine, colloidal silica as an abrasive particle, a formula ( 1) The polishing liquid containing the organic acid represented by 1) and the corrosion inhibitor on the polishing platen at a flow rate of 0.035 to 0.25 ml / (min · cm ² ) per unit area and unit time of the semiconductor substrate. A polishing pad is supplied, and polishing is performed by relatively moving the polishing pad and the surface to be polished in contact with each other.

式中、Ｒ¹及びＲ²は、各々独立に、水素原子、アルキル基、フェニル基、カルボキシル基、水酸基又はアミノ基を置換した有機基を表す。ｎは０又は１を表す。

In the formula, R ¹ and R ² each independently represents a hydrogen atom, an alkyl group, a phenyl group, a carboxyl group, a hydroxyl group, or an organic group substituted with an amino group. n represents 0 or 1.

  Until now, as the amount of polishing liquid used during processing was reduced, the cooling effect of the polishing liquid was impaired, and as a result, the processing temperature during polishing increased and dishing and erosion had deteriorated. . In order to prevent this, a composition in which the polishing rate of copper is low (having sufficient corrosion inhibiting ability) during processing and at high temperatures is desired. However, it is difficult to achieve the above composition because the inhibiting ability of the corrosion inhibitor is reduced at high temperatures.

  Unlike the conventional polishing liquid (slurry), the reason why the amount of the polishing liquid used in the present invention can be reduced is that the polishing liquid is 7-hydroxy-5-methyl-1,3,4-triazaindolizine. This is probably because the organic acid represented by the formula (1) and the corrosion inhibitor are contained. That is, the organic acid represented by the formula (1) can easily control the elution rate of copper (Cu) by the addition amount of an oxidizing agent such as hydrogen peroxide. In addition, a combination of 7-hydroxy-5-methyl-1,3,4-triazaindolizine and a corrosion inhibitor forms a composite film that can sufficiently inhibit corrosion even at high temperatures. This makes it possible to perform polishing at a low temperature without generating excessive frictional heat even at a very low polishing flow rate.

Here, the polishing liquid flow rate is a flow rate of the polishing liquid supplied to the object to be polished per minute, and is defined as a flow rate with respect to the area of the object to be polished (substrate wafer area). Here, in the present invention, the flow rate of the polishing liquid per unit area and unit time supplied to the object to be polished during polishing is 0.035 to 0.25 ml / (min · cm ² ). From the viewpoint of not excessively increasing the processing temperature, it is more preferably 0.100 to 0.25 ml / (min · cm ² ).
When the polishing liquid flow rate is less than 0.035 ml / (min · cm ² ), the processing temperature rises excessively and good polishing results cannot be obtained. Moreover, when it exceeds 0.25 ml / (min · cm ² ), it leads to high cost.

  The polishing liquid is a concentrated liquid, and when it is used, it is diluted with water to make a working liquid. In some cases, it is prepared as a working solution or a working solution. The polishing method using the polishing liquid of the present invention can be applied to any case, supplying the polishing liquid to the polishing pad on the polishing surface plate, and bringing the polishing surface and the polishing pad into relative motion by bringing them into contact with the surface to be polished. This is a polishing method for polishing.

  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 0.68 to 34.5 KPa, and the in-plane uniformity of the polishing target (wafer) and the pattern of the polishing rate In order to satisfy flatness, it is more preferably 3.40 to 20.7 KPa.

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

  As a method of diluting the concentrated polishing liquid by adding water or an aqueous solution, the pipe for supplying the concentrated polishing liquid and the pipe for supplying the water or the aqueous solution are joined together and mixed, and mixed and diluted. There is a method of supplying a polishing pad to a polishing pad. Mixing is a method in which liquids collide with each other through a narrow passage under pressure, a method in which a filling such as a glass tube is filled in a 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.

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

  According to another polishing method of the present invention, the component to be contained in the polishing liquid is divided into at least two components, and when these components are used, they are diluted by adding water or an aqueous solution and supplied to the polishing pad on the polishing platen. In this method, the surface to be polished and the polishing pad are moved relative to each other and brought into contact with the surface to be polished. For example, an oxidizing agent is one component (A), an acid, an additive, a surfactant and water are one component (B), and when they are used, the component (A) The component (B) is diluted before use.

  In addition, the low-solubility additive is divided into two components (A) and (B), and the oxidizing agent, additive and surfactant are one component (A), and the acid, additive, surfactant and Water is used as one component (B), and when these are used, water or an aqueous solution is added to dilute the component (A) and the component (B). In the case of this example, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are required, and dilution mixing is performed on one pipe that supplies the three pads to the polishing pad. There is a method of combining and mixing in the pipe. In this case, it is also possible to combine two pipes and then connect another pipe.

  For example, it is a method in which a constituent component containing an additive that is difficult to dissolve is mixed with another constituent component, a mixing path is lengthened to ensure a dissolution time, and then a pipe of water or an aqueous solution is further combined. Other mixing methods are as described above, in which the three pipes are each guided directly to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished, and the three components are mixed in one container. The diluted polishing liquid 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 the solubility increases when the temperature is high, this is a preferable method for increasing the solubility of the raw material having a low solubility of the polishing liquid.

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

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

(Barrier metal)
In the present invention, when a wiring made of carbon is used as the semiconductor, it is preferable to provide a barrier layer for preventing diffusion of trace elements between the wiring and the interlayer insulating film. The barrier layer is preferably a metal material with low electrical resistance, more preferably TiN, TiW, Ta, TaN, W, WN, and Ru, and particularly preferably Ta, TaN, and Ru.
As the interlayer insulating film, a thin film of an insulating material having a low dielectric constant is preferable, and a preferable insulating material is a material having a relative dielectric constant of 3.0 or less, more preferably a material having a dielectric constant of 2.8 or less. . Specific examples of preferable low dielectric constant materials include BlackDiamond (Applied Materials), FLARE (Honeywell Electronic Materials), SILK (Dow Chemical), CORAL (Novellus System), LKD (JSR) And HSG (manufactured by Hitachi Chemical Co., Ltd.).

(pad)
The polishing pad used in the present invention 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 to be polished using the carbon wiring polishing liquid of the present invention preferably has a diameter of 200 mm or more, particularly preferably 300 mm or more. When it is 300 mm or more, the effect of the present invention can be remarkably exhibited, which is preferable.

[Polishing liquid]
In the present invention, the polishing liquid contains 7-hydroxy-5-methyl-1,3,4-triazaindolizine, colloidal silica as polishing particles, an organic acid represented by the formula (1), and a corrosion inhibitor. If necessary, it contains an oxidizing agent, an acid, an additive, a surfactant, a hydrophilic polymer, an alkali agent and a buffer.

Of the components added during the preparation of the concentrated liquid of the polishing liquid, the blending amount of water having a solubility in water of less than 5% at room temperature is room temperature in order to prevent precipitation when the concentrated liquid is cooled to 5 ° C or the like. The solubility in water is preferably 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, It is diluted and used for polishing. The dilution factor is generally 1 to 20 volume times.
In the present invention, the “polishing liquid” means not only a polishing liquid used for polishing (that is, a polishing liquid diluted as necessary) but also a concentrated liquid of the polishing liquid.
Hereinafter, each component will be described.

(Organic acid represented by formula (1))
In the present invention, the polishing liquid contains an organic acid represented by the formula (1).

In the formula, R ¹ and R ² each independently represents a hydrogen atom, an alkyl group, a phenyl group, a carboxyl group, a hydroxyl group, or an organic group substituted with an amino group. n represents 0 or 1. R ¹ and R ² are preferably a hydrogen atom, an alkyl group and a hydroxyl group.
In addition, in the description of substituents (atomic groups) in the compounds in the present specification, when neither substituted nor unsubstituted is described, it includes not only those having no substituent but also those having a substituent. is there. 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).

Examples of the organic acid represented by the formula (1) include malic acid, tartaric acid, citric acid and derivatives thereof. Among these, the unsubstituted malic acid, tartaric acid and citric acid are particularly preferable.
Although the organic acid represented by Formula (1) can be used alone, a plurality of organic acids represented by Formula (1) can be used in combination.

  The organic acid can be synthesized by a known method, but a commercially available product may be used. The total amount of the organic acid represented by the formula (1) is preferably 0.001 to 5% by weight, more preferably 0.01 to 3% by weight in 1 L of a polishing liquid used for polishing. .

(7-hydroxy-5-methyl-1,3,4-triazaindolizine)
In the present invention, the polishing liquid has 7-hydroxy-5-methyl-1,3,4-triazaindolizine.
The blending amount of 7-hydroxy-5-methyl-1,3,4-triazaindolizine is preferably 0.01 to 5% by weight, more preferably 0.05 to 2% by weight. More preferably, it is made into 1 to 1 weight%. It is preferable for this content to be 0.01% by weight or more because the occurrence of scratches can be sufficiently suppressed. Further, if it is 5% by weight or less, it is preferable because 7-hydroxy-5-methyl-1,3,4-triazaindolizine is sufficiently dissolved and precipitation does not occur.

(Abrasive particles)
The polishing liquid used in the present invention contains colloidal silica as abrasive particles as a constituent component.
Examples of the method for producing the colloidal silica particles include silicon alkoxides 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 the compound by a sol-gel method. Such first and second colloidal particles (for example, first and second colloidal silica particles) have a very sharp particle size distribution.

  The average particle size of the colloidal particles is a particle size cumulative curve showing the relationship between the particle size of the colloidal particles and the cumulative frequency obtained by integrating the number of particles having the particle size. It means the particle diameter. 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 size 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 contained is preferably 0.5 to 15% by weight in the polishing liquid. More preferably, it is 1 to 10% by weight. In order to achieve a sufficient polishing speed, the concentration is preferably 0.5% by weight or more. The concentration is preferably 10% by weight or less for the purpose of not generating excessive frictional heat during polishing.

(Corrosion inhibitor)
In the present invention, the polishing liquid contains at least one corrosion inhibitor as a compound that forms a passive film on the metal surface to be polished and suppresses a chemical reaction on the substrate.
As a corrosion inhibitor, it is preferable to use a heterocyclic compound.
More preferably, the corrosion inhibitor is benzotriazole and its derivatives. Examples of the derivatives include 5,6-dimethyl-1,2,3-benzotriazole (DBTA), 1- (1,2-dicarboxyethyl) benzotriazole (DCEBTA), 1- [N, N-bis (hydroxy). Ethyl) aminomethyl] benzotriazole (HEABTA) is preferred.

  The corrosion inhibitor used in the present invention may be used alone or in combination of two or more. Moreover, the corrosion inhibitor used by this invention can be synthesize | combined according to a conventional method, and may use a commercial item.

The addition amount of the corrosion inhibitor is preferably 0.01 wt% or more and 0.2 wt% or less, more preferably 0.05 wt% or more and 0.2 wt% or less.
It is preferable that the addition amount of the corrosion inhibitor be 0.01% by weight or more because a corrosion inhibitory effect can be exhibited. Moreover, it is preferable that the addition amount of the corrosion inhibitor is 0.2% by weight or less because the particles can maintain high stability.

(Other ingredients)
Further, the polishing liquid of the present invention may further contain other components, and preferred components include an oxidizing agent, an organic acid, an inorganic acid, a surfactant, a water-soluble polymer, and an additive. The above components contained in the polishing liquid may be used alone or in combination of two or more.

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

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

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

Of these, organic complex salts of hydrogen peroxide, iodate, hypochlorite, chlorate, and iron (III) are preferred, and preferred complex-forming compounds when using an organic complex salt of iron (III) are 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), ethylenediaminedisuccinic acid (SS), N- (2-carboxylateethyl) -L-aspartic acid, N- (carboxymethyl) -L- Aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).
Among the oxidizing agents, hydrogen peroxide and iron (III) ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid and ethylenediaminedi A succinic acid (SS body) complex is most preferable.

As a density | concentration of the oxidizing agent in the metal polishing liquid of this invention, it is preferable that it is 1 weight% or less, and it is more preferable that it is 0.5 weight%.
Moreover, the addition amount of the oxidizing agent is preferably 0.003 mol to 8 mol, more preferably 0.03 mol to 6 mol, and more preferably 0.1 mol to 4 mol in 1 L of the polishing liquid used for polishing. 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 the acid include inorganic acids and organic acids within the range.
Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid, and among the inorganic acids, phosphoric acid and nitric acid are preferable.
In the present invention, other organic acids can be used in combination with the organic acid represented by the formula (1). The organic acid that can be used in combination is preferably a water-soluble one. 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 lactic acid, and salts thereof such as ammonium salts and alkali metal salts, sulfuric acid, nitric acid, ammonia, ammonium salts, or mixtures thereof Etc. Of these, formic acid, acetic acid and glycolic acid are preferred.

(Additive)
Moreover, it is preferable to use the following additives for the polishing liquid of the present invention.
ammonia;
Alkylamines such as dimethylamine, trimethylamine, triethylamine, propylenediamine, and amines such as ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate and chitosan;
Dithizone, cuproin (2,2′-biquinoline), neocuproin (2,9-dimethyl-1,10-phenanthroline), bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and cupelazone ( Imines such as 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-hexylbenzotriazol N- (1,2,3-benzotriazolyl-1-methyl) -N- (1,2,4-triazolyl-1-methyl) -2-ethylhexylamine, tolyltriazole, naphthotriazole, bis [( Azoles such as 1-benzotriazolyl) methyl] phosphonic acid;
Mercaptans such as nonyl mercaptan, dodecyl mercaptan, triazine thiol, triazine dithiol, triazine trithiol,
Other examples include tetrazole and quinaldic acid.
Among these, chitosan, ethylenediaminetetraacetic acid, cuperazone, triazinedithiol, benzotriazole, 4-hydroxybenzotriazole, 44-butoxycarbonyl-1H-benzotriazole, tolyltriazole, and naphthotriazole satisfy both high CMP rate and low etching rate. Preferred above.

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

(Surfactant and / or hydrophilic polymer)
The polishing liquid of the present invention preferably contains a surfactant and / or a hydrophilic polymer.
Both the surfactant and the hydrophilic polymer have the action of reducing the contact angle of the surface to be polished and the action of promoting uniform polishing. As the surfactant and / or hydrophilic polymer to be used, those selected from the following group are suitable.
Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. Examples of the carboxylate salt include 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 polyoxypropyls. Can pyrene alkyl allyl ether phosphates.

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 , 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 thereof; 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- Rylsulfonic 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 exemplary compounds, polyacrylic acid ammonium salt, polyvinyl alcohol, succinic acid amide, polo vinyl pyrrolidone, polyethylene glycol, and polyoxyethylene polyoxypropylene block polymer are more preferable.

The total amount of the surfactant and / or hydrophilic polymer added is preferably 0.001 to 10 g and more preferably 0.01 to 5 g in 1 L of a polishing liquid used for polishing. It is particularly preferably 0.1 to 3 g. That is, the addition amount of the surfactant and / or the hydrophilic polymer is preferably 0.001 g or more for obtaining a sufficient effect, and is preferably 10 g or less from the viewpoint of preventing the CMP rate from being lowered.
Moreover, as a weight average molecular weight of these surfactant and / or hydrophilic polymer, 500-100,000 are preferable, and 2,000-50,000 are especially preferable.

(Alkaline agent and buffer)
In the present invention, the polishing liquid may contain an alkali agent for pH adjustment, and further a buffering agent from the viewpoint of suppressing fluctuations in pH, if necessary.

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

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

  The addition amount of the alkaline agent and the buffer may be an amount that maintains the pH within a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of the polishing liquid used for polishing. More preferably, it is 0.003 mol to 0.5 mol.

2-8 are preferable, as for pH of the metal polishing liquid of this invention, More preferably, it is pH 2-7, More preferably, it is pH 2-4. Within this range, the metal liquid of the present invention exhibits particularly excellent effects.
In addition, the form which does not contain water may be sufficient as the metal polishing liquid of this invention. In this case, the metal polishing liquid having a pH of 2 to 8 represents one having the above pH when the metal polishing liquid of the present invention is dissolved in water.

  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.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Abbreviations of the compounds used in this example are described below.
BTA: benzotriazole DBTA: 5,6-dimethyl-1,2,3-benzotriazole DCEBTA: 1- (1,2-dicarboxyethyl) benzotriazole HEABTA: 1- [N, N-bis (hydroxyethyl) amino Methyl] benzotriazole

<Example 1>
The polishing liquid shown below was prepared and evaluated for polishing with this polishing system.
(Preparation of polishing liquid)
The following composition was mixed to prepare a polishing liquid.
Colloidal silica particles (PL3) 50g / L
Malic acid (organic acid, Wako Pure Chemical Industries, Ltd.) 10g / L
BTA (benzotriazole) (aromatic ring compound) 1.0 g / L
7-hydroxy-5-methyl-1,3,4-triazaindolizine 0.1 g / L
Hydrogen peroxide 4g / L
Add pure water, total volume 1000mL
pH (adjusted with ammonia water and nitric acid) pH 2.5

(Evaluation methods)
Using a device “F-REX300” manufactured by Ebara Corporation as a polishing device, polishing the film provided on each patterned wafer while supplying slurry (polishing liquid) under the following conditions and measuring the level difference at that time did.
Object to be polished (substrate): A silicon oxide film is patterned by a photolithography process and a reactive ion etching process to form wiring grooves and connection holes having a width of 0.09 to 100 μm and a depth of 600 nm, and a sputtering method. A 12-inch wafer was used in which a Ta film having a thickness of 20 nm was formed, a copper film having a thickness of 50 nm was subsequently formed by a sputtering method, and then a copper film having a total thickness of 1000 nm was formed by a plating method.
Table rotation speed: 65 rpm
Head rotation speed: 50 rpm
Polishing pressure: 13.79 KPa
Polishing pad: Part number IC-1400 manufactured by Rodel Nitta Co., Ltd.
Polishing liquid supply speed: 150 ml / min (0.21 ml / min · cm ² )

1) <Dishing evaluation>
In addition to the time until the copper in the non-wiring portion is completely polished, a wafer subjected to primary polishing for a time corresponding to 50% of the time was used for the pattern wafer (primary post-dishing: line 100 μm / space 100 μm). 60 nm). Using this wafer, dishing (line 100 μm / space 100 μm) of the wafer polished with each slurry (polishing liquid) for 30 seconds was measured with a stylus type step gauge Dektak V320Si (Veeco). Further, it was confirmed that there was no polishing residue on the entire wafer surface after polishing.

2) <Scratch evaluation>
The presence or absence of peeling of the outer peripheral portion of the wafer after the chemical mechanical polishing treatment and the number of scratches were evaluated. The wafer after chemical mechanical polishing as described above was washed and dried, then observed visually and with an optical microscope, and the number of scratches on the entire wafer surface was measured.

<Examples 2 to 18 and Comparative Example 1>
Except for abrasive particles and organic acid, the same compounds as in Example 1 were used, and the polishing tests of Examples 2 to 18 and Comparative Example 1 were performed according to the polishing conditions described in Table 1. The results are shown in Table 1.

  According to the result of Table 1, in 1-18 slurry containing 7-hydroxy-5-methyl-1,3,4-triazaindolizine, colloidal silica as an abrasive particle and an organic acid represented by formula (1), Low dishing and low scratching are achieved at a low polishing liquid supply speed. On the other hand, in the comparative example 1 which does not contain the organic acid represented by Formula (1), dishing became a very big value.

  As described above, according to the polishing method of the present invention, in chemical mechanical polishing of a film to be processed of a semiconductor device, the amount of low polishing liquid used (low cost) and dishing hardly deteriorate, and high performance LSI processing It can be seen that can be done.

Claims (3)

A polishing substrate containing 7-hydroxy-5-methyl-1,3,4-triazaindolizine, colloidal silica as polishing particles, an organic acid represented by formula (1), and a corrosion inhibitor is a semiconductor substrate unit. Supply to the polishing pad on the polishing surface plate at a flow rate of 0.035 to 0.25 ml / (min · cm ² ) per area and unit time,
A chemical-mechanical polishing method comprising polishing by relatively moving a polishing pad and a surface to be polished in contact with each other.

In the formula, R ¹ and R ² each independently represents a hydrogen atom, an alkyl group, a phenyl group, a carboxyl group, a hydroxyl group, or an organic group substituted with an amino group. n represents 0 or 1.   The chemical mechanical polishing method according to claim 1, wherein the organic acid represented by the formula (1) is selected from the group consisting of malic acid, tartaric acid, citric acid, and derivatives thereof. The chemical mechanical polishing method according to claim 1 or 2, wherein the corrosion inhibitor contains benzotriazole or a derivative thereof.