JP2006278798A - Polishing composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing composition which uses organic resin fine grains as an abrasive and reduces foaming. <P>SOLUTION: A polishing composition contains organic resin fine grains (A), surfactant (B), and defoaming agent (C). The defoaming agent (C) is preferably at least one or more kinds of defoaming agents selected from among silica silicone defoaming agent containing hydrophobic silica, metal soap defoaming agent containing metal soap, and oxide wax defoaming agent containing oxide wax. Thus, the problems, wherein it becomes difficult to uniformly supply the polishing composition, or uniform polishing cannot be performed because of foaming of the surfactant contained in the polishing composition for diffusing the organic resin fine grains or improving the smoothness on the surface of a copper film (1), and wherein trouble occurs in drainage, since waste water after polishing foam up are solved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to a polishing composition used for polishing semiconductors, various memory hard disk substrates and the like, and more particularly to a polishing composition suitably used for surface planarization of semiconductor device wafers.

    Recent advances in the electronics industry have evolved into transistors, ICs, LSIs, and super LSIs. As the degree of integration of circuits in these semiconductor elements has increased rapidly, the design rules for semiconductor devices have become finer year by year. The depth of focus in the device manufacturing process has become shallower, and the flatness of the pattern formation surface has become increasingly severe

    On the other hand, in order to cover the increase in wiring resistance due to the miniaturization of wiring, copper wiring having a smaller electrical resistance has been studied as a wiring material from aluminum or tungsten. However, when copper is used for interconnection between wiring layers and wirings, after forming wiring grooves and holes on the insulating film, a copper film is formed by sputtering or plating, and unnecessary portions are chemically and mechanically polished. It is necessary to remove unnecessary copper on the insulating film by (CMP).

    In such a process, copper diffuses into the insulating film and degrades the device characteristics. Therefore, in order to prevent copper diffusion, it is common to provide a tantalum or tantalum nitride layer as a barrier layer on the insulating film. Yes.

In the planarization CMP process for a device having a copper film formed on the uppermost layer in this manner, an unnecessary portion of the copper film is first polished to the surface layer of the tantalum compound formed on the insulating layer, and the next step Then, the tantalum compound layer on the insulating film must be polished and the polishing must be completed when the SiO ₂ surface comes out. Such a process is shown in FIG. 1, and CMP polishing in such a process requires that the polishing rate be selective with respect to different materials such as copper, a tantalum compound, and SiO ₂ .

That is, in Step 1, the polishing rate with respect to copper is high and the tantalum compound needs to be selective enough to have no polishing ability. Further, in step 2, the polishing rate for the tantalum compound is large, but the smaller the polishing rate for SiO ₂ is, the more preferable it is because it is possible to prevent excessive polishing of SiO ₂ .

Ideally, this process can be polished with a single abrasive, but the selectivity of the polishing rate for different materials cannot be changed during the process, so the process is divided into two steps and has different selectivity. Each CMP step is performed with two slurries. In order to prevent excessive etching (dishing, recessing, erosion) of the copper film in the normal groove or hole, the polishing is finished in step 1 with a little copper film on the tantalum compound left. In step 2, the remaining copper and tantalum compound are removed by polishing using the SiO ₂ layer as a stopper.

  For the polishing composition used in Step 1, it is necessary to have a large polishing rate only for the copper film without causing surface defects (scratches) that cannot be corrected in Step 2.

As such a polishing composition for a copper film, Patent Document 1 discloses a polishing composition containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent, and water. . This polishing composition has a relatively high polishing rate with respect to copper, and this is because copper ionized by an oxidizing agent forms a chelate with the above organic acid and is easily mechanically polished. It can be estimated that this is because
However, when polishing a semiconductor device having a copper film and a tantalum compound using the polishing composition, the polishing selectivity of copper and tantalum compound is not sufficient, or if the selectivity to copper is increased, the wiring trench and hole copper There have been problems such as excessive film shaving and loss of smoothness on the copper film surface.
In order to solve these problems, Patent Document 2 discloses a polishing composition containing organic resin fine particles as an abrasive and improving the dispersion stability of organic resin fine particles with a surfactant.
JP-A-7-233485 JP 2003-313540 A

However, the prior art described in the above literature has room for improvement in the following points.
First, it is difficult to uniformly supply the polishing composition due to foaming of the surfactant contained to disperse the organic resin fine particles and improve the smoothness of the copper film surface. Therefore, there was a problem that uniform polishing was not possible.
Secondly, there is a problem that the waste water treatment becomes inconvenient because the ground waste water is foamed.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polishing composition using organic resin fine particles as a polishing material with less foaming.

[1] (A) Organic resin fine particles,
(B) a surfactant, and
(C) antifoaming agent,
Polishing composition containing this.
[2] The polishing composition according to [1], wherein (B) the surfactant is one or more surfactants selected from an anionic surfactant and a nonionic surfactant.
[3] The polishing composition according to [1] or [2], wherein the (C) antifoaming agent is a silicone-based antifoaming agent.
[4] The antifoaming agent (C) is a silica silicone antifoaming agent containing hydrophobic silica, a metal soap antifoaming agent containing metal soap, or an oxidized wax antifoaming agent containing oxidized wax. The polishing composition according to any one of [1] to [4], which is one or more selected antifoaming agents.

  According to the present invention, a polishing composition capable of preferentially polishing a copper film in a CMP process of a semiconductor device including a copper film and a tantalum film can be obtained without causing inconveniences such as foaming during polishing. A semiconductor device can be efficiently manufactured.

The present invention relates to a polishing composition containing (A) organic resin fine particles, (B) a surfactant, and (C) an antifoaming agent. The following is an example, and the present invention is not limited to the following. Hereinafter, each component of the polishing composition of the present invention will be described in detail.

    The present invention includes (A) organic resin fine particles as an abrasive. It is not particularly limited as long as it is a fine particle of an organic polymer compound. For example, fine particles of an organic polymer compound obtained by emulsion polymerization of a vinyl monomer, and organic polymers obtained by polycondensation such as polyester, polyamide, polyimide, polybenzoxazole, etc. Examples thereof include fine particles of molecular compounds and fine particles of organic polymer compounds obtained by addition condensation such as phenol resin and melamine resin. These may be used singly or in any combination of a plurality of different organic polymer compound fine particles. Preferable examples include vinyl polymers that are relatively inexpensive and have a uniform particle size and low polarity.

    The average particle diameter of the organic resin fine particles of the present invention is in the range of 10 to 500 nm, preferably in the range of 20 to 200 nm. If it is smaller than the lower limit value, the polishing rate of the copper film is small, so that it is not suitable as a polishing application. If the upper limit value is exceeded, it becomes difficult to disperse the particles and the surface flattening function is impaired. The concentration in the polishing composition of the present invention is 0.1 to 5% by weight, preferably 0.5 to 3% by weight. However, the present invention is not particularly limited to this range. If the concentration is less than the lower limit, a sufficient polishing rate cannot be obtained, which is inconvenient. If the concentration exceeds the upper limit, it becomes difficult to disperse the particles, and problems such as aggregation and sedimentation tend to occur.

    The polishing composition of the present invention contains (B) a surfactant. The surfactant is preferably an anionic surfactant or a nonionic surfactant, but the present invention is not particularly limited thereto. These surfactants may be used alone or in combination of two or more. Specific examples of the anionic surfactant include carboxylates such as laurate, stearate and oleate, sulfate esters such as higher alcohol sulfates and polyoxyalkylene alkyl ether sulfates. And sulfonates such as alkylbenzene sulfonate, alkylnaphthalene sulfonate, and paraffin sulfonate, and phosphate esters such as higher alcohol phosphate esters and polyoxyalkylene alkyl ether phosphate salts. Examples of the salt structure include sodium salt, potassium salt and ammonium salt. Specific examples of the nonionic surfactant include polyoxyalkylene alkyl ether and polyoxyalkylene alkylphenyl ether. The surfactant in the present invention has an effect of improving the dispersion stability of the organic resin fine particles and improving the uniformity of the polishing rate. The concentration in the polishing composition in the present invention is 0.0001 to 1% by weight, preferably 0.01 to 0.5% by weight. However, the present invention is not limited to this range. If the lower limit is added, no effect is observed, and if the upper limit is exceeded, the concentration may be too high, and precipitation may occur.

The polishing composition of the present invention contains (C) an antifoaming agent. Although not particularly limited, a silicone-based antifoaming agent is preferable. Specific examples of the silicone antifoaming agent include a silica silicone antifoaming agent containing hydrophobic silica, a metal soap antifoaming agent containing metal soap, and an oxidized wax antifoaming agent containing oxidized wax. . These antifoaming agents are provided as a mixture with mineral oil or a surfactant to improve the antifoaming effect and dispersibility. By adding an antifoaming agent, foaming due to a surfactant or the like can be suppressed, and defects such as deposits on the copper film surface caused by bubbles can be improved. In addition, the influence on workability such as mixing and foaming of drainage can be improved. The addition amount in the polishing composition of the present invention is 0.0001 to 1% by weight, preferably 0.001 to 0.1% by weight. However, the present invention is not limited to this range. Even if it is added at the lower limit, the effect is not sufficient, and if it exceeds the upper limit, the concentration is too high and it is difficult to disperse.

The polishing composition of the present invention may contain an amino acid as necessary. Specific examples of amino acids include glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, phenylalanine, tyrosine, tryptophan, proline, asparagine, glutamine, aspartic acid, glutamic acid, lysine, histidine and arginine. It is done. Of these, glycine, alanine, serine and histidine are preferred, and glycine is more preferred. These amino acids may be used alone, or two or more different amino acids may be used in combination. However, the present invention is not limited to these. The amount added is in the range of 0.01 to 10% by weight in the polishing composition. Moreover, although it does not specifically limit, Preferably it is the range of 0.1 to 5 weight%. If the amount of amino acid added is less than the lower limit, the polishing rate is insufficient, and if it exceeds the upper limit, the polishing rate cannot be controlled, causing problems such as overpolishing and surface corrosion of the copper film.

The polishing composition of the present invention can contain benzotriazole as necessary. The concentration in the polishing composition of the present invention is 0.0001 to 1% by weight. Moreover, although it does not specifically limit, Preferably it is the range of 0.001-0.5 weight%. If it is the lower limit, the polishing rate of the copper film cannot be sufficiently controlled, which is inconvenient. If the upper limit is exceeded, the polishing rate of the copper film is extremely lowered.

The polishing composition of the present invention can contain an amine as necessary. Specific examples of amines include ethanolamine, diethanolamine, triethanolamine, ethylenediamine, dimethylamine, and diethylamine. Of these, ethanolamine, diethanolamine and triethanolamine are preferred, and ethanolamine is more preferred. These amines may be used alone or in combination of two or more different amines. However, the present invention is not limited to these. About addition amount, it uses in 0.001 to 1 weight% of range in polishing composition. Moreover, although it does not specifically limit, Preferably it is the range of 0.005-0.5 weight%. If the amount of amine added is less than the lower limit, the polishing rate is not stable enough. If the amount exceeds the upper limit, problems such as overpolishing and surface corrosion of the copper film may occur.

    The polishing composition of the present invention can contain hydrogen peroxide as necessary. In the polishing composition according to the present invention, hydrogen peroxide acts as an oxidizing agent. Hydrogen peroxide exerts an oxidizing action on the copper film and works to increase the polishing rate of the copper film by promoting ionization, but the concentration in the polishing composition in the present invention is 0.01 to 10%. % By weight. Although not particularly limited, a range of 0.1 to 5% by weight is preferable. If it is less than the lower limit value, a sufficient polishing rate cannot be obtained, which is inconvenient. If the upper limit value is exceeded, copper surface roughening or dishing may be caused.

  As a medium for the polishing composition of the present invention, it is desirable to use water in which ionic impurities and metal ions are reduced as much as possible. That is, it is preferable that the impurity ions are removed with an ion exchange resin and the suspension is removed through a filter, or distilled water.

  The polishing composition of the present invention is produced by mixing, dissolving, and dispersing organic resin fine particles, surfactant, antifoaming agent, and if necessary, amino acid, benzotriazole, and amine in water. Hydrogen peroxide is added to and mixed with the above-mentioned liquid mixture immediately before polishing, but can also be mixed in advance. The mixing method can be performed with any apparatus. For example, a blade-type rotary stirrer, an ultrasonic disperser, a bead mill disperser, a kneader, a ball mill, and the like are applicable.

    In addition to the above components, various polishing aids may be blended. Examples of such polishing aids include dispersants, rust inhibitors, pH adjusters, fungicides and the like, and these are added for the purpose of improving the dispersion storage stability of the slurry and the polishing rate. Needless to say, the dispersibility can be improved by adding a water-soluble polymer such as polyvinyl alcohol. Examples of the pH adjuster include basic compounds such as ammonia, acetic acid, hydrochloric acid, nitric acid and the like.

The present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
<Example 1>
Table 1 shows cross-linked resin fine particles of methyl methacrylate having an average particle size of about 40 nm and divinylbenzene, polyoxyethylene nonylphenyl ether sulfate ammonium salt, silica silicone antifoaming agent, glycine, benzotriazole, airanolamine and hydrogen peroxide. The polishing composition of Example 1 was obtained by mixing with ion-exchanged water filtered through a 0.5 μm cartridge filter so as to have the concentration shown in FIG.

<Abrasiveness evaluation>
The object to be polished was prepared by forming a 1500-inch tantalum (Ta) film by sputtering on an 8-inch silicon wafer and 15000-thick copper film by electrolytic plating, and polishing the copper and Ta surfaces.

For polishing, a single-side polishing machine having a surface plate diameter of 600 mm was used. A polyurethane polishing pad IC-1000 / Suba400 manufactured by Rodel (USA) was attached to the surface plate of the polishing machine, and a copper and tantalum film was polished for 1 minute while flowing the polishing composition (slurry). As polishing conditions, the load was 300 g / cm ² , the rotation speed of the surface plate was 40 rpm, the rotation speed of the wafer was 40 rpm, and the flow rate of the polishing composition was 200 ml / min.

    The polishing rate (Å / min) was determined by determining the film thickness that decreased after washing and drying the wafer. The ratio of the polishing rate of copper to the polishing rate of tantalum was taken as the selection ratio.

The polished surface was examined by observing the polished surface with an optical microscope, and the following ranking was performed.
◎: Good, ○: Some smoothness is slightly insufficient but usable, △: Defects such as deposits are generated, ×: Corrosion is generated

The foaming of the polishing composition was examined and classified into the following ranks.
◎: Almost no foam, ○: Foaming disappears immediately, ×: Foam does not disappear easily

<Examples 2-5, Comparative Examples 1-3>
The organic resin fine particles AB, colloidal silica, surfactant AB, antifoaming agent AC, glycine, benzotriazole, ethanolamine and hydrogen peroxide are 0.5 μm so as to have the concentrations shown in Table 1. The mixture was mixed with ion-exchanged water filtered through a cartridge filter, stirred with a high-speed homogenizer and uniformly dispersed to prepare a polishing composition in the same manner as in Example 1, and the polishing property was evaluated in the same manner as in Example 1. It was.
The evaluation results are shown in Table 1.

Each component used in Table 1 will be described below.
(1) Organic resin fine particles A: Crosslinked resin fine particles having an average particle diameter of about 40 nm obtained by emulsion polymerization by a known method using methyl methacrylate as a non-crosslinking monomer and divinylbenzene as a crosslinking monomer.
(2) Organic resin fine particles B: Thermosetting resin fine particles having an average particle size of about 200 nm, obtained by addition condensation using a known method using melamine and formaldehyde as monomers.
(3) Colloidal silica: Colloidal silica having an average particle size of 30 nm (Fuso Chemical: PL-3)
(4) Surfactant A: Polyoxyethylene nonylphenyl ether sulfate ammonium salt (Miyoshi oil and fat: Spamine W)
(5) Surfactant B: Polyoxyethylene lauryl ether sulfate sodium salt (Kao: Emar E-27C)
(6) Antifoaming agent A: Silica silicone-based antifoaming agent (San Nopco: Nopco 8034-L)
(7) Defoaming agent B: Metal soap type defoaming agent (San Nopco: Nopco NXZ)
(8) Antifoaming agent C: oxidized wax-based antifoaming agent (San Nopco: Nopco DF-124-L)
(9) Reagents were used for glycine, benzotriazole, and ethanolamine.
(10) Hydrogen peroxide: 30% hydrogen peroxide water was used.

  The polishing composition of the present invention is suitably used for surface planarization of a semiconductor device wafer.

Schematic of polishing process for devices with copper film

Explanation of symbols

1 Cu
2 Ta
3 SiO ₂

Claims (4)

(A) Organic resin fine particles,
(B) a surfactant, and
(C) antifoaming agent,
Polishing composition containing this.     The polishing composition according to claim 1, wherein the (B) surfactant is one or more surfactants selected from anionic surfactants and nonionic surfactants. The polishing composition according to claim 1 or 2, wherein the (C) antifoaming agent is a silicone-based antifoaming agent. The (C) antifoaming agent was selected from a silica silicone antifoaming agent containing hydrophobic silica, a metal soap antifoaming agent containing metal soap, or an oxidized wax antifoaming agent containing oxidized wax. The polishing composition according to claim 1, wherein the polishing composition is one or more antifoaming agents.

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