JP2006287076A - Polishing composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved polishing composition by solving the problems that the polishing selection ratio of copper to a tantalum compound is insufficient when a semiconductor device having a copper film and the tantalum compound is polished, a wiring groove and the copper film of a hole are excessively scrapped when the selection ratio to the copper is increased, smoothness on the surface of the copper film is damaged, or the like. <P>SOLUTION: The polishing composition contains fine particles of an organic resin (A), and an anionic surfactant having polyoxyethylene-polyoxypropylene block copolymer chain in a molecule (B). <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 amino 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, but this is because copper ionized by an oxidizing agent forms a chelate with the above amino acid and is easily mechanically polished. Can be estimated.
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 copper in the wiring groove or hole There have been problems such as excessive film shaving and loss of smoothness on the copper film surface.
JP-A-7-233485

  An object of the present invention is to provide a polishing composition having a high selectivity in which the polishing rate of copper is high but the polishing rate of tantalum compound is low in the CMP process of a semiconductor device having a copper film and a tantalum compound. It is a polishing composition for CMP processing excellent in smoothness of the copper film surface.

[1] A polishing composition containing (A) organic resin fine particles and (B) an anionic surfactant having a polyoxyethylene polyoxypropylene block polymer chain in the molecule.
[2] The component (B) is a polyoxyethylene polyoxypropylene sulfate, polyoxyethylene polyoxypropylene alkyl ether sulfate, polyoxyethylene polyoxypropylene alkylphenyl ether sulfate, polyoxyethylene polyoxy The polishing composition according to [1], comprising a propylene sulfate ammonium salt, a polyoxyethylene polyoxypropylene alkyl ether sulfate ammonium salt, or a polyoxyethylene polyoxypropylene alkylphenyl ether sulfate ammonium salt.
[3] The polishing composition according to [1] or [2], further comprising (C) an anionic surfactant having a polyoxyethylene chain in the molecule (excluding the component (B)) .
[4] The polishing composition according to [3], wherein the component (C) contains a polyoxyethylene alkyl ether sulfate ester salt or a polyoxyethylene alkyl phenyl ether sulfate ester salt.
[5] The polishing composition according to [3] or [4], wherein the component (C) comprises a polyoxyethylene alkyl ether sulfate ammonium salt or a polyoxyethylene alkyl phenyl ether sulfate ammonium salt object.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing composition which can grind | polish a copper film preferentially in the CMP processing process of the semiconductor device containing a copper film and a tantalum film is obtained, and a semiconductor device can be manufactured efficiently.

  As a result of various investigations in order to solve the above-mentioned problems, the present invention uses a polishing composition containing a specific abrasive, compound, oxidant and water, so that the polishing rate for a copper film is large and tantalum is used. The inventors have found that the polishing rate with respect to the compound is small, that high selectivity can be obtained, and that the smoothness of the copper film surface is excellent, and that the present invention has been completed.

  The present invention relates to a polishing composition containing (A) organic resin fine particles and (B) an anionic surfactant having a polyoxyethylene polyoxypropylene block polymer chain in the molecule. 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 which 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 preferably in the range of 10 to 200 nm, more preferably in the range of 20 to 150 nm. When the thickness is larger than 10 nm, the polishing rate of the copper film increases, so that it is more suitable as a polishing application. These fine particles can be obtained by a known method in which necessary monomers are subjected to suspension polymerization or emulsion polymerization.

  The concentration of the organic resin fine particles in the polishing composition of the present invention is preferably 0.1 to 5% by weight, more preferably 0.5 to 3% by weight. When the concentration is 0.1% by weight or more, a more appropriate polishing rate is obtained. When the concentration is less than 5% by weight, the dispersibility of the particles is improved, so that problems such as aggregation and sedimentation hardly occur.

  The polishing composition of the present invention contains (B) an anionic surfactant having a polyoxyethylene polyoxypropylene block polymer chain in the molecule. The polyoxyethylene polyoxypropylene block polymer chain refers to a polymer chain having both a part containing a plurality of exciethylene units and a part containing a plurality of oxypropylene units. It is preferable that both parts are like a block copolymer. About the aspect of a block copolymer, a comb type, a star type, a gradient type etc. are included besides a normal block type.

  The surfactant in the present invention acts on the surface of the copper film to suppress dishing and improves the selectivity between the copper film and the insulating film and has the effect of preventing erosion.

  Specific examples of the component (B) include polyoxyethylene polyoxypropylene sulfate, polyoxyethylene polyoxypropylene alkyl ether sulfate, polyoxyethylene polyoxypropylene alkyl phenyl ether sulfate, and the like. These salts may be used alone or in combination of two or more.

  Specific examples of polyoxyethylene polyoxypropylene alkyl ether sulfates include polyoxyethylene polyoxypropylene oleyl ether sulfate, and specific examples of polyoxyethylene polyoxypropylene alkylphenyl ether sulfates include polyoxyethylene polyoxypropylene. Examples thereof include oxypropylene nonylphenyl ether sulfate ester salt. Among these, ammonium salts such as polyoxyethylene polyoxypropylene ammonium sulfate, polyoxyethylene polyoxypropylene oleyl ether ammonium sulfate, and polyoxyethylene polyoxypropylene nonylphenyl ether ammonium sulfate are most preferred as the salt composition.

  The concentration of the component (B) in the polishing composition in the present invention is preferably 0.0001 to 1% by weight, more preferably 0.001 to 0.5% by weight. When the amount is 0.0001% by weight or more, the effect is high at the time of addition, and when the amount is less than 1% by weight, the polishing inhibition of the abrasive grains and the adverse effect on the polishing rate can be further suppressed.

  The polishing composition of the present invention preferably contains (C) an anionic surfactant having a polyoxyethylene chain in the molecule (excluding the component (B)). (C) The anionic surfactant having a polyoxyethylene chain in the molecule does not contain the anionic surfactant of component (B).

  By using the component (C) in the present invention in combination with the component (B), it is possible to further suppress dishing, improve the selectivity between the copper film and the insulating film, and prevent erosion.

  Specific examples of the anionic surfactant include polyoxyethylene alkyl ether sulfate ester salt, polyoxyethylene alkylphenyl ether sulfate ester salt and the like. These salts may be used alone or in combination of two or more.

  Specific examples of the polyoxyethylene alkyl ether sulfate ester salt include polyoxyethylene oleyl ether sulfate ester salt. Specific examples of the polyoxyethylene alkyl phenyl ether sulfate ester salt include polyoxyethylene nonylphenyl ether sulfate ester. . Among these, the salt is most preferably an ammonium salt such as ammonium polyoxyethylene oleyl ether sulfate or ammonium polyoxyethylene nonylphenyl ether sulfate.

  The concentration of the component (C) in the polishing composition in the present invention is preferably 0.0001 to 1% by weight, more preferably 0.001 to 0.5% by weight. When the amount is 0.0001% by weight or more, the effect is high at the time of addition, and when it is less than 1% by weight, the polishing inhibition of the abrasive grains and the adverse effect on the polishing rate can be further suppressed.

  The polishing composition of the present invention can 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.

  The amount of amino acid added is preferably in the range of 0.01 to 10% by weight in the polishing composition. More preferably, it is the range of 0.1 to 5 weight%. When it exceeds 0.01% by weight, the polishing rate becomes more appropriate, and when it is less than 10% by weight, the polishing rate can be easily controlled, and problems of overpolishing and surface corrosion of the copper film can be suppressed.

The polishing composition of the present invention can contain benzotriazole as necessary. The concentration in the polishing composition of the present invention is preferably 0.0001 to 0.5% by weight. More preferably, it is 0.01 to 0.25% by weight. When it is 0.0001% by weight or more, it becomes easy to control the polishing rate of the copper film, and when it is less than 0.5% by weight, the polishing rate of the copper film is improved.

  The polishing composition of the present invention can contain an amine as necessary. Preferable examples of the amine include monoethanolamine, diethanolamine, triethanolamine, and ethylenediamine. These amines are mainly used for adjusting the pH of the polishing composition and controlling the polishing rate of the copper film.

  The concentration of amine in the polishing composition is preferably 0.001 to 0.5% by weight. When the amount is 0.001% by weight or more, the polishing rate becomes more appropriate. When the amount is less than 0.5% by weight, the polishing rate is easily controlled, and problems of overpolishing and surface corrosion of the copper film are easily suppressed.

  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 preferably 0.01. -10% by weight. A range of 0.1 to 5% by weight is more preferable. When it is 0.01% by weight or more, the polishing rate becomes more appropriate, and when it is less than 10% by weight, it becomes easy to suppress copper surface roughness and dishing.

  The medium of the polishing composition of the present invention is preferably water, and it is desirable to reduce ionic impurities and metal ions 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 the above-described organic resin fine particles, an anionic surfactant, and, if necessary, an amino acid, benzotriazole, and an 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, antifoaming agents, pH adjusters, fungicides, etc., and these are intended to improve the dispersion storage stability of the slurry and the polishing rate. Added in. 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. Examples of antifoaming agents include liquid paraffin, dimethyl silicone oil, stearic acid glyceride mixture, sorbitan monopalmitate and the like.

The present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
<Example 1>
0.5 μm so that the polycondensate of polymethyl methacrylate (PMMA) with an average particle size of 40 nm and divinylbenzene, surfactant A, hydrogen peroxide, glycine, benzotriazole, and amine have the concentrations shown in Table 1. Was mixed with ion-exchanged water filtered with a cartridge filter of No. 1 and stirred uniformly with a high-speed homogenizer to uniformly disperse to obtain the polishing composition of Example 1.

<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). The polishing conditions were a load of 300 g / cm ² , a platen rotation speed of 80 rpm, a wafer rotation speed of 80 rpm, and a polishing composition flow rate of 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. Further, the polished surface was examined by observing the polished surface with an optical microscope, and the following ranking was performed.
◎: Good, ○: Partially slightly smooth but usable, △: Good smoothness but partial corrosion, ×: Corrosion occurred

  The dishing evaluation (nm), which is a phenomenon in which the center of the Cu wiring becomes thin, was measured by using a stylus type surface roughness meter on an L / S = 100 μm wiring pattern after 60 seconds of overpolishing.

<Examples 2-6, Comparative Examples 1-8>
Ion exchange water filtered with a 0.5 μm cartridge filter so that the organic resin fine particles A and B, surfactants A and B, hydrogen peroxide, amino acid, benzotriazole, and amine have the concentrations shown in Table 1. The mixture was stirred and dispersed uniformly with a high-speed homogenizer 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.
The evaluation results are shown in Table 1.

Details of each component used in Table 1 are as follows.
(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) Surfactant A: Polyoxyethylene polyoxypropylene alkyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd .: Hightenol LF710)
(4) Surfactant B: Polyoxyethylene alkyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd .: Highenol 08E)
(5) Reagents were used for glycine, benzotriazole, and monoethanolamine.
(6) 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 (5)

(A) Organic resin fine particles,
(B) an anionic surfactant having a polyoxyethylene polyoxypropylene block polymer chain in the molecule;
Polishing composition containing this.   The component (B) is a polyoxyethylene polyoxypropylene sulfate, polyoxyethylene polyoxypropylene alkyl ether sulfate, polyoxyethylene polyoxypropylene alkyl phenyl ether sulfate, polyoxyethylene polyoxypropylene sulfate The polishing composition according to claim 1, comprising an ammonium salt, a polyoxyethylene polyoxypropylene alkyl ether sulfate ammonium salt, or a polyoxyethylene polyoxypropylene alkylphenyl ether sulfate ammonium salt.   The polishing composition according to claim 1 or 2, further comprising (C) an anionic surfactant having a polyoxyethylene chain in the molecule (excluding the component (B)).   The polishing composition according to claim 3, wherein the component (C) contains a polyoxyethylene alkyl ether sulfate ester salt or a polyoxyethylene alkyl phenyl ether sulfate ester salt.   The polishing composition according to claim 3 or 4, wherein the component (C) contains a polyoxyethylene alkyl ether sulfate ammonium salt or a polyoxyethylene alkyl phenyl ether sulfate ammonium salt.

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