JP2015028968A - Aqueous dispersoid for chemical mechanical polishing, chemical mechanical polishing method, and kit for preparing aqueous dispersoid for chemical mechanical polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an aqueous dispersoid for chemical mechanical polishing by which in a semiconductor post process, a copper film can be polished flatly at a high speed and the occurrence of a surface defect of the copper film can be suppressed; and a chemical mechanical polishing method using the same.SOLUTION: An aqueous dispersoid for chemical mechanical polishing according to the present invention is one for polishing a wiring layer made of copper or a copper alloy and formed on a printed board. The aqueous dispersoid for chemical mechanical polishing comprises (A) an amino acid, (B) grinding grains, (C) a surfactant, (D) an oxidant, and (E) ammonia. The ratio (W/W) of a content (W) of the amino acid to a content (W) of the oxidant is 6.0-50. The ratio (W/W) of a content (W) of the ammonia to a content (W) of the oxidant is 0.6-5.0.

Description

  The present invention relates to a chemical mechanical polishing aqueous dispersion, a chemical mechanical polishing method, and a chemical mechanical polishing aqueous dispersion preparation kit.

  Conventionally, copper damascene wiring mounted on a high-performance LSI has been used in a semiconductor pre-process (hereinafter also simply referred to as “pre-process”). In recent years, even in a printed circuit board in a semiconductor post-process (hereinafter also simply referred to as a “post-process”), a damascene process is being adopted for wiring formation due to the progress of miniaturization with the miniaturization of chips.

  In the present specification, the “semiconductor pre-process” refers to a process of simultaneously forming a large number of IC chips on a wafer. On the other hand, the “semiconductor post-process” refers to a process of forming a conductor wiring on a circuit board (printed board or the like) on which an IC chip, a transistor or the like is mounted.

  Incidentally, the copper damascene wiring is formed by chemical mechanical polishing (hereinafter also referred to as “CMP”). In the post-process CMP, a first polishing process in which the deposited copper film is polished at high speed until just before the resin film is exposed, and a second polishing in which these films are simultaneously polished while maintaining the flatness of the copper film and the resin film. A polishing step is performed. In the first polishing process, (1) the copper film is polished at high speed while maintaining flatness without substantially polishing the resin film, and (2) the influence on the subsequent second polishing process is minimized. In order to limit this, it is required to reduce the corrosion and scratches on the copper film as much as possible. As a polishing composition used in such a first polishing step, a polishing composition containing, for example, alumina, a complexing agent and an oxidizing agent has been proposed (see, for example, Patent Document 1). .

  Conventionally, there has also been a first polishing step in which the copper film is polished at a high speed in the previous step. As a polishing composition used in this pre-process, for example, a polishing composition containing an amino acid, abrasive grains, a surfactant, an oxidizing agent and ammonia has been proposed (see, for example, Patent Document 2).

JP 2005-268666 A JP 2010-4023 A

  However, since the polishing composition described in Patent Document 1 uses alumina as abrasive grains, it has a problem of causing severe surface roughness and scratches on the surface of the copper film.

On the other hand, the polishing composition described in Patent Document 2 is a polishing composition used in the previous step as described above, but the film thickness of the copper film in the previous step is 2 μm or less, and the size of the wafer is also large. The maximum was 300 mm. On the other hand, the film thickness of the copper film used in the subsequent process is as thick as 5 μm or more, and the substrate area is as large as 500 mm square. Moreover, the surface of the copper film used in the post-process is mainly composed of oxidized copper oxide, and the properties are greatly different from those of the copper film in the pre-process. Therefore, even if the polishing composition described in Patent Document 2 is applied to the post-process CMP,
There was a problem that the polishing rate for the copper film was remarkably reduced, leading to a reduction in throughput.

  Therefore, some aspects of the present invention provide a chemical mechanical polishing water capable of polishing the copper film at high speed and flatness and suppressing the occurrence of surface defects of the copper film in the semiconductor post-process by solving the above-described problems. A system dispersion and a chemical mechanical polishing method using the same are provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the chemical mechanical polishing aqueous dispersion according to the present invention is:
A chemical mechanical polishing aqueous dispersion for polishing a wiring layer made of copper or a copper alloy formed on a printed circuit board,
(A) an amino acid, (B) an abrasive, (C) a surfactant, (D) an oxidant, and (E) ammonia,
The content of the amino acid content of _{(W A)} and the oxidizing agent _{(W D)} ratio of _(W A / W _D) is from 6.0 to 50, and the content of the ammonia _(W E) And a ratio (W _E / W _D ) between the content of the oxidant (W _D ) and 0.6 to 5.0.

[Application Example 2]
In the chemical mechanical polishing aqueous dispersion of Application Example 1,
The content (W A) of the amino acid ( _A ) may be 3% by mass or more and 18% by mass or less with respect to the total mass of the chemical mechanical polishing aqueous dispersion.

[Application Example 3]
In the chemical mechanical polishing aqueous dispersion of Application Example 1 or Application Example 2,
The content (W _E ) of (E) ammonia may be 0.4% by mass or more and 2% by mass or less with respect to the total mass of the chemical mechanical polishing aqueous dispersion.

[Application Example 4]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 3,
The (A) amino acid may be at least one selected from the group consisting of glycine, alanine and glutamic acid.

[Application Example 5]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 4,
The said (B) abrasive grain can be colloidal silica.

[Application Example 6]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 5,
The surfactant (C) may be at least one selected from the group consisting of potassium dodecylbenzenesulfonate, ammonium dodecylbenzenesulfonate, and dipotassium alkenyl succinate.

[Application Example 7]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 6,
The (D) oxidizing agent may be hydrogen peroxide.

[Application Example 8]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 7,
The pH can be 7-11.

[Application Example 9]
One aspect of the chemical mechanical polishing aqueous dispersion preparation kit according to the present invention,
A kit composed of a first composition and a second composition for preparing the chemical mechanical polishing aqueous dispersion of any one of Application Examples 1 to 8.
The first composition contains (A) an amino acid, (B) an abrasive, (C) a surfactant, and (E) ammonia,
The second composition contains (D) an oxidizing agent.

[Application Example 10]
One aspect of the chemical mechanical polishing aqueous dispersion preparation kit according to the present invention,
A kit comprising a third composition and a fourth composition for preparing the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 8.
The third composition contains (A) an amino acid and (E) ammonia,
The fourth composition contains (B) abrasive grains and (C) a surfactant.
At least one selected from the third composition and the fourth composition contains (D) an oxidizing agent.

[Application Example 11]
In the chemical mechanical polishing aqueous dispersion preparation kit of Application Example 10,
The fourth composition may further contain (E) ammonia.

[Application Example 12]
One aspect of the chemical mechanical polishing aqueous dispersion preparation kit according to the present invention,
A kit comprising a fifth composition, a sixth composition and a seventh composition for preparing the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 8. ,
The fifth composition contains (A) an amino acid and (E) ammonia,
The sixth composition contains (B) abrasive grains and (C) a surfactant,
The seventh composition contains (D) an oxidizing agent.

[Application Example 13]
In the chemical mechanical polishing aqueous dispersion preparation kit of Application Example 12,
The sixth composition may further contain (E) ammonia.

[Application Example 14]
One aspect of the chemical mechanical polishing method according to the present invention is:
It includes a step of polishing a wiring layer made of copper or a copper alloy formed on a printed board using the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 8.

  According to the chemical mechanical polishing aqueous dispersion, the copper film can be polished at high speed and flatly in the semiconductor post-process, and the occurrence of surface defects such as corrosion on the copper film can be suppressed.

It is sectional drawing which shows typically a specific example of the chemical mechanical polishing method. It is a perspective view which shows a chemical mechanical polishing apparatus typically.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, Various modifications implemented in the range which does not change the summary of this invention are also included.

1. Chemical mechanical polishing aqueous dispersion The chemical mechanical polishing aqueous dispersion according to one embodiment of the present invention comprises (A) an amino acid, (B) abrasive grains, (C) a surfactant, and (D) an oxidation. _A ratio of the amino acid content (W _A ) and the oxidizing agent content (W _D ) (W _A / W _D ) of 6.0 to 50 There, and the content of the ammonia _{(W E)} and the content of the oxidizing agent _{(W D)} and the ratio of _(W E / W _D) is characterized in that it is a 0.6 to 5.0. First, each component constituting the chemical mechanical polishing aqueous dispersion according to the present embodiment will be described.

1.1. (A) Amino acid The chemical mechanical polishing aqueous dispersion according to this embodiment contains (A) an amino acid. (A) An amino acid has a property which tends to form a coordinate bond with a copper ion, and forms a coordinate bond with the surface of the copper film which is a surface to be polished. Thereby, since the affinity with copper and copper ions can be increased while maintaining high flatness while suppressing surface roughness of the copper film, the polishing rate of the copper film can be improved. Moreover, (A) an amino acid can coordinate easily with the copper ion eluted into the slurry by polishing the copper film, and can prevent the precipitation of copper. As a result, it is possible to suppress the occurrence of polishing defects such as scratches on the copper film.

  (A) Examples of amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, parin, etc. Is mentioned. These (A) amino acids can be used alone or in combination of two or more.

  The chemical mechanical polishing aqueous dispersion according to the present embodiment preferably contains at least one selected from the group consisting of glycine, alanine and glutamic acid among the amino acids exemplified above, and may contain glycine. Particularly preferred. Glycine, alanine and glutamic acid have particularly strong properties of forming a coordinate bond with copper ions, and have a particularly high effect of increasing the polishing rate of the copper film.

  The content of (A) amino acid is preferably 3% by mass or more and 18% by mass or less, more preferably 5% by mass or more and 17.5% by mass or less with respect to the total mass of the chemical mechanical polishing aqueous dispersion. (A) When the amino acid content is less than the above range, a sufficiently high polishing rate for the copper film may not be obtained. On the other hand, if the content of (A) amino acid exceeds the above range, dishing of the copper film tends to be large, and flatness may be impaired.

1.2. (B) Abrasive Grain The chemical mechanical polishing aqueous dispersion according to the present embodiment contains (B) abrasive grains. (B) The abrasive has an effect of mechanically polishing the copper film. (B) As an abrasive grain, inorganic particles, such as a silica, a ceria, an alumina, a zirconia, a titania, are mentioned, for example.

Silica particles include: (a) fumed silica synthesized by the fumed method in which silicon chloride, aluminum chloride, titanium chloride or the like is reacted with oxygen and hydrogen in the gas phase; (b) synthesized by hydrolytic condensation from metal alkoxide. And silica synthesized by a sol-gel method; (c) colloidal silica synthesized by an inorganic colloid method in which impurities are removed by purification. Among these, (b) silica synthesized by a sol-gel method synthesized by hydrolytic condensation from a metal alkoxide in terms of being alkaline and stable at pH 7 to 11 and excellent in compatibility with an anionic surfactant, And (c) colloidal silica synthesized by an inorganic colloid method or the like from which impurities have been removed by purification. Moreover, colloidal silica is more preferable from the viewpoint of suppressing generation of scratches on the surface of the copper film.

  (B) The average secondary particle diameter of the abrasive is preferably 5 to 1000 nm, more preferably 10 to 700 nm, and particularly preferably 15 to 500 nm. When the average secondary particle diameter is within the above range, a stable chemical mechanical polishing aqueous dispersion is obtained in which the polishing rate for the copper film is high, dishing is sufficiently suppressed, and particle settling and separation are unlikely to occur. be able to. This average secondary particle size is measured by measuring the intensity of scattered light using a particle size distribution measuring device based on the dynamic light scattering method, obtaining the autocorrelation function by the photon correlation method, and analyzing the cumulant method and the histogram method. Can be obtained by applying.

  (B) The content of abrasive grains is preferably 0.2% by mass or more and 10% by mass or less, and more preferably 0.3% by mass or more and 5% by mass with respect to the total mass of the chemical mechanical polishing aqueous dispersion. %, Particularly preferably 0.4% by mass or more and 4% by mass. (B) When the content of the abrasive grains is in the above range, a sufficient polishing rate for the copper film can be obtained in the semiconductor post-process, and a stable chemical mechanical polishing aqueous dispersion in which precipitation and separation of particles are difficult to occur. Easy to obtain.

1.3. (C) Surfactant The chemical mechanical polishing aqueous dispersion according to this embodiment contains (C) a surfactant. (C) By containing surfactant, the dispersion stability of the said (B) abrasive grain can be improved, protecting the copper film surface in a semiconductor back process. This makes it possible to perform polishing while maintaining the flatness of the copper film, and (B) the dispersibility of the abrasive grains is improved, so that the surface roughness of the copper film and the occurrence of scratches can be suppressed.

  (C) As surfactant, anionic surfactant, a cationic surfactant, and a nonionic surfactant are mentioned.

  Examples of the anionic surfactant include aliphatic soap, alkylbenzene sulfonate, sulfate ester salt, phosphate ester salt, and other anionic surfactants. As the alkylbenzene sulfonate, potassium dodecylbenzenesulfonate, ammonium dodecylbenzenesulfonate and the like are preferably used. As the aliphatic soap, potassium oleate or the like is preferably used. As another anionic surfactant, dipotassium alkenyl succinate is preferably used.

  Examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts.

  Examples of the nonionic surfactant include a nonionic surfactant having a triple bond and a polyethylene glycol type surfactant. Examples of the nonionic surfactant having a triple bond include acetylene glycol, acetylene glycol ethylene oxide adduct, and acetylene alcohol. Polyvinyl alcohol, cyclodextrin, polyvinyl methyl ether, hydroxyethyl cellulose and the like can also be used.

Among the surfactants (C), an anionic surfactant is preferably used from the viewpoint of polishing while maintaining the flatness of the copper film in the semiconductor post-process, and potassium dodecylbenzenesulfonate and ammonium dodecylbenzenesulfonate are used. And at least one selected from the group consisting of dipotassium alkenyl succinate is more preferable.

  The content of the (C) surfactant is preferably 0.01% by mass or more and 0.5% by mass or less, more preferably 0.1% by mass or more and 0% by mass with respect to the total mass of the chemical mechanical polishing aqueous dispersion. .5% by mass or less.

1.4. (D) Oxidizing agent The chemical mechanical polishing aqueous dispersion according to this embodiment contains (D) an oxidizing agent. (D) By containing an oxidizing agent, the surface of the copper film is oxidized and promotes a complexing reaction with the polishing liquid component, thereby creating a fragile modified layer on the surface of the copper film and making it easy to polish the copper film. There is an effect to.

  Examples of the (D) oxidizing agent include ammonium persulfate, potassium persulfate, hydrogen peroxide, ferric nitrate, diammonium cerium nitrate, iron sulfate, ozone, potassium periodate, and peracetic acid. These (D) oxidizing agents may be used individually by 1 type, and may be used in combination of 2 or more type. Of these (D) oxidants, ammonium persulfate, potassium persulfate, and hydrogen peroxide are preferable, and hydrogen peroxide is more preferable in consideration of oxidizing power, compatibility with the protective film, and ease of handling.

  (D) The content of the oxidizing agent is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, with respect to the total mass of the chemical mechanical polishing aqueous dispersion. Especially preferably, it is 0.5 mass% or more and 1.5 mass% or less. (D) When content of an oxidizing agent is less than the said range, since the surface of a copper film cannot fully be oxidized, the polishing rate of a copper film may become small. On the other hand, when the above range is exceeded, corrosion of the copper film tends to occur.

1.5. (E) Ammonia The chemical mechanical polishing aqueous dispersion according to this embodiment contains (E) ammonia. Ammonia has the effect of improving the polishing rate by forming a chelate with the copper film. In the chemical mechanical polishing aqueous dispersion according to the present embodiment, the polishing rate of the copper film can be improved by increasing the content ratio of (E) ammonia and effectively forming a chelate with the copper film.

  (E) The content of ammonia is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.4% by mass or more and 2% by mass or less, with respect to the total mass of the chemical mechanical polishing aqueous dispersion. is there. (E) When the ammonia content is within the above range, a sufficient polishing rate for the copper film can be obtained, and the copper film can be polished without causing corrosion.

1.6. Content Ratio The chemical mechanical polishing aqueous dispersion according to the present embodiment has not been found in the past by precisely defining the contents of (A) amino acid, (D) oxidizing agent, and (E) ammonia. High speed polishing of a copper film can be realized. Furthermore, this content regulation makes it possible not only to polish the copper film at a high speed but also to have excellent planarization characteristics and hardly cause surface defects such as corrosion.

The reason why the ratio (W _A / W _D ) of (1) (A) amino acid content (W _A ) and (D) oxidant content (W _D ) is specified will be described below.

In general, the surface of a copper film deposited on a printed circuit board is easily oxidized because it has a large area, and is covered with a thick and hard copper oxide. Further, the surface of the copper film is also oxidized by (D) an oxidizing agent to become copper oxide. It is considered that elution of copper occurs when these copper oxides complex with (A) amino acids. Therefore, in order to realize high-speed polishing of the copper film, it is necessary to appropriately control (D) the copper oxidation reaction by the oxidizing agent and (A) the copper oxide complex formation reaction by the amino acid.

  First, considering from the viewpoint of the oxidation reaction of copper by (D) oxidizing agent, the amount of copper oxide produced has a correlation with the content of (D) oxidizing agent, and a large amount of (D) oxidizing agent is used. The amount of copper oxide produced can be increased. However, simply using a large amount of the (D) oxidizing agent cannot elute copper oxide, and high-speed polishing of the copper film cannot be realized. That is, when the content of (D) the oxidizing agent is too large, the amount of copper oxide produced increases, but in the presence of a small amount of (A) amino acid, the amount of complexation reaction of copper is small and the polishing rate is improved. I can't. In addition, when the content of the oxidizing agent (D) is too large, copper peroxide is generated, and (A) the complexing reaction of copper by amino acids is inhibited, resulting in a decrease in the polishing rate for the copper film. D) It is necessary to define the content of the oxidizing agent. On the other hand, when the content of (D) the oxidizing agent is small, the amount of copper oxide produced decreases, so even if a large amount of (A) amino acid is present, the amount of complexation reaction of copper is small and the polishing rate is improved. I can't let you.

  Next, from the viewpoint of (A) the complexation reaction of copper oxide with amino acids, (A) the complexation reaction of copper oxide with amino acids has a chemical equilibrium, and therefore contains a large amount of (A) amino acids. Thus, the reaction proceeds in the direction of forming a complex, and the polishing rate of the copper film can be improved. However, if a large amount of (A) amino acid is present in the chemical mechanical polishing aqueous dispersion, the aggregation of (B) abrasive grains may be promoted during the polishing step, and the flatness of the copper film may be impaired. In addition, the chemical mechanical polishing aqueous dispersion containing a large amount of (A) amino acid may cause aggregation or sedimentation of (B) abrasive grains due to long-term storage, thereby impairing storage stability.

From the above viewpoint, in order to ensure the storage stability of the chemical mechanical polishing aqueous dispersion and to achieve high-speed polishing of the copper film in the semiconductor post-process, the (A) amino acid content (W _A ) and The ratio (W _A / W _D ) to the content (W _D ) of the (D) oxidant needs to be 6.0 to 50, preferably 7.0 to 48, and 8.0 to 8.0. 47 is more preferable. When W A _/ W _D is less than 6.0, the content of (A) amino acids are relatively small, (D) since the content of the oxidizing agent is relatively excessive, the complexation reaction as described above The balance is lost and high-speed polishing of the copper film cannot be realized. On the other hand, if W A _/ W _D exceeds 50, (D) is relatively small content of the oxidizing agent, (A) since the content of amino acids is relatively excessive, the balance of the complex formation reaction described above The high-speed polishing of the copper film cannot be realized.

The reason why the ratio (W _E / W _D ) of (2) (E) ammonia content (W _E ) and (D) oxidant content (W _D ) is specified will be described below.

  (E) Unlike (A) amino acids, ammonia can react directly with copper to form a complex without going through copper oxide. (E) Ammonia can complex with copper to increase the polishing rate of the copper film. However, if a large amount of (E) ammonia is used, the surface of the copper film is chemically corroded and copper is removed. Causes film surface roughness and scratches. Such corrosion can be suppressed by increasing the amount of copper oxide produced. However, since the content of (D) the oxidant contributes to the complexation reaction of copper oxide by (A) amino acid as described above, simply increasing the content of (D) oxidant loses the balance. Will be. Therefore, (A) without inhibiting the complexation reaction of copper oxide by amino acids (E) corrosion of the copper film by ammonia can be suppressed, and the polishing rate of the copper film can be maximized (E) ammonia and ( D) It is necessary to define the content of the oxidizing agent.

From the above viewpoint, in order to ensure a good surface to be polished without surface roughness and scratches of the copper film, and to realize high-speed polishing of the copper film, the above (E) ammonia content (W _E ) and the above (D) The ratio (W _E / W _D ) to the oxidant content (W _D ) needs to be 0.6 to 5.0, preferably 0.7 to 4.0, 0 More preferably, it is 8 to 3.5. W
When _{E /} W _D is less than 0.6, (E) the ammonia content is relatively small, (D) since the content of the oxidizing agent is relatively excessive, the balance of the complex formation reaction described above Thus, high-speed polishing of the copper film cannot be realized. When W E _/ W _D exceeds 5, (E) becomes relatively excessive amount of ammonia, (D) since the content of the oxidizing agent is relatively small, loss inhibitory effect of corrosion reactions described above Surface roughness and scratches of the copper film occur.

(3) (A) the molar ratio _(M E / M _A) of the molar concentration of amino acids _{(M A)} and (E) the molar concentration of ammonia _{(M E)} is preferably from 0.2 to 2, More preferably, it is 0.4-1. (E) Ammonia acts as a complexing accelerator for amino acids that replace amino acid-copper complexes with ammonia-copper complexes, so (E) ammonia is blended in an appropriate concentration with respect to (A) amino acids. Thus, polishing can be performed more effectively. If M _E / M _A is less than 0.2, (E) the content of ammonia is less than (A) amino acids, complex formation of amino acids is not promoted, and high-speed polishing of the copper film cannot be performed efficiently. There is a case. When M _E / M _A exceeds 2, (E) the ammonia content becomes excessive with respect to (A) amino acids, there is a large amount of ammonia that does not contribute to the formation of the ammonia-copper complex, and the corrosion reaction by ammonia occurs. May go forward.

  The chemical mechanical polishing aqueous dispersion according to this embodiment satisfies both the above conditions (1) and (2) simultaneously (preferably, the above condition (3) is also satisfied). The effect of this can be achieved. That is, according to the present invention, by setting the above-mentioned appropriate content ratio, the chemical polishing action by (A) amino acid based on the complex formation reaction of copper oxide and (A) amino acid, and the complex formation reaction of copper and (E) ammonia. (E) These chemical polishing actions can be used in combination while maintaining a balance with the chemical polishing action by ammonia. Thereby, in the semiconductor post-process, the copper film can be polished at high speed and flat, and the occurrence of surface defects such as corrosion on the copper film can be suppressed.

1.7. Other Additives The chemical mechanical polishing aqueous dispersion according to this embodiment may contain the following components (a) to (d) as necessary.
(A) Complexing agents such as phthalic acid, maleic acid and citric acid.
(B) Antioxidants such as benzotriazole.
(C) Water-soluble polymers such as polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, and polyvinylpyrrolidone.
(D) Oxidation / complex formation auxiliary agents such as ammonium sulfate.

1.8. pH
The pH of the chemical mechanical polishing aqueous dispersion according to the present embodiment is not particularly limited, but is preferably 7 to 11, more preferably 8 to 10, and particularly preferably 8.5 to 10. If the pH is less than 7, high-speed polishing of the copper film may not be realized. On the other hand, when pH exceeds 11, it may be inferior to the surface roughness on a copper film, and the inhibitory effect of a scratch. Examples of the pH adjuster include basic salts such as potassium hydroxide, ethylenediamine, and TMAH (tetramethylammonium hydroxide).

1.9. Applications The chemical mechanical polishing aqueous dispersion according to the present embodiment is a chemical mechanical polishing process for a semiconductor film, that is, a chemical mechanical polishing of a copper film formed as a conductor wiring on a circuit board such as a printed circuit board on which an IC chip, a transistor, or the like is mounted. It can be used as an abrasive for Specifically, it can be used as an abrasive when forming a copper damascene wiring in a semiconductor post-process. In the semiconductor post-process, the process of forming the copper damascene wiring by chemical mechanical polishing includes a first polishing process for removing the copper film and a second polishing process for simultaneously polishing the copper film and the resin film. Since the chemical mechanical polishing aqueous dispersion can polish the copper film at high speed, it is effective when used in the first polishing step.

2. Chemical Mechanical Polishing Method A specific example of the chemical mechanical polishing method according to the present embodiment will be described in detail with reference to the drawings. 1A and 1B are cross-sectional views schematically showing a specific example of the chemical mechanical polishing method according to the present embodiment.

2.1. To-be-processed object The to-be-processed object 100 is shown to FIG. 1 (A). As illustrated in FIG. 1A, the workpiece 100 includes a substrate 10. The substrate 10 has at least a functional device (not shown) such as an IC chip or a transistor.

  The target object 100 includes an insulating resin film 12 formed on the substrate 10. In general, examples of the resin film 12 include glass epoxy resin, polyimide resin, paper epoxy resin, and bakelite resin. When forming a wiring structure on the substrate 10, first, a wiring recess 14 based on circuit design is formed on the surface of the resin film 12 by a known lithography technique and / or etching technique. Next, a copper film 16 is formed on the surface of the resin film 12 so that at least the wiring recesses 14 are completely filled. In general, the copper film 16 is formed by PVD, CVD, electroplating, or the like. As a material for the copper film 16, not only high-purity copper but also an alloy containing copper can be used. The copper content in the alloy containing copper is preferably 95% by mass or more.

2.2. Polishing Step Next, as shown in FIG. 1 (B), using the chemical mechanical polishing aqueous dispersion, the copper film 16 other than the portion buried in the wiring recess 14 is fastened until the resin film 12 is exposed. Grind. As a result, the copper film 16 and the resin film 12 are exposed on the surface of the workpiece 100, and both are formed smoothly and flush with each other. As a result, a conductor wiring is formed in the wiring recess 14. The polishing rate of the copper film at this time is preferably 4 μm / min or more, more preferably 8 μm / min or more. Thereby, high throughput can be achieved in the semiconductor post-process.

  In such a polishing process, for example, a chemical mechanical polishing apparatus 200 as shown in FIG. 2 can be used. FIG. 2 is a perspective view schematically showing the chemical mechanical polishing apparatus 200. The slurry 44 is supplied from the slurry supply nozzle 42, and the carrier head 52 holding the printed circuit board 50 is brought into contact with the turntable 48 to which the polishing pad 46 is attached. In FIG. 2, the water supply nozzle 54 and the dresser 56 are also shown.

The polishing load of the carrier head 52 can be selected within a range of 1 to 100 kPa, and preferably 3 to 50 kPa. Moreover, the rotation speed of the turntable 48 and the carrier head 52 can be suitably selected within the range of 10 to 400 rpm, and preferably 30 to 150 rpm. Flow rate of the slurry 44 supplied from the slurry supply nozzle 42 may be selected within the range of 10~1,000cm ³ / min, preferably 50~400cm ³ / min.

  In this polishing step, a commercially available chemical mechanical polishing apparatus can be used. As a commercially available chemical mechanical polishing apparatus, for example, “EPO-112”, “EPO-222” manufactured by Ebara Manufacturing Co., Ltd .; “LGP-510”, “LGP-552” manufactured by LAPMASTER SFT, Inc .; For example, model “Mirra”, manufactured by G & P Technology, model “POLI-400L”, and the like.

3. Chemical Mechanical Polishing Aqueous Dispersion Preparation Kit The chemical mechanical polishing aqueous dispersion can be supplied in a state where it can be used as a polishing composition as it is after preparation. Alternatively, a polishing composition (that is, a concentrated polishing composition) containing each component of the chemical mechanical polishing aqueous dispersion at a high concentration is prepared, and the concentrated polishing composition is used at the time of use. It may be diluted to obtain a desired chemical mechanical polishing aqueous dispersion.

  In addition, as described below, a plurality of compositions (for example, two or three compositions) containing any of the above components can be prepared, and these can be mixed and used at the time of use. In this case, after preparing a chemical mechanical polishing aqueous dispersion by mixing a plurality of liquids, this may be supplied to the chemical mechanical polishing apparatus, or a plurality of liquids may be supplied individually to the chemical mechanical polishing apparatus. A chemical mechanical polishing aqueous dispersion may be prepared on a surface plate. For example, the chemical mechanical polishing aqueous dispersion can be prepared by mixing a plurality of liquids using the following first to third kits.

3.1. First Kit The first kit according to the present embodiment includes (A) an amino acid, (B) abrasive grains, (C) a surfactant, (E) a first composition containing ammonia and water, (D) A kit for preparing the above-mentioned chemical mechanical polishing aqueous dispersion by mixing these compositions with a second composition containing an oxidizing agent and water.

  The concentration of each component in the first composition and the second composition is such that the concentration of each component in the chemical mechanical polishing aqueous dispersion finally prepared by mixing these compositions is within the above range. If it becomes, it will not specifically limit. For example, the first composition and the second composition containing each component at a concentration higher than the concentration of the intended chemical mechanical polishing aqueous dispersion are prepared, and the first composition is used as necessary at the time of use. And the 2nd composition is diluted, these are mixed and the aqueous dispersion for chemical mechanical polishing from which the density | concentration of each component becomes the said range is prepared. Specifically, when the first composition and the second composition are mixed at a mass ratio of 1: 1, 2 of each component contained in the target chemical mechanical polishing aqueous dispersion. What is necessary is just to prepare a 1st composition and a 2nd composition, respectively so that it may become a density | concentration of double. In addition, the first composition and the second composition were respectively prepared so as to have a concentration twice or more that of each component contained in the target chemical mechanical polishing aqueous dispersion, and these were prepared at a mass of 1: 1. After mixing at a ratio, each component may be diluted with water so as to have a desired concentration.

  According to the first kit, the storage stability of the oxidizing agent contained in the second composition can be particularly improved by separately preparing and storing the first composition and the second composition. it can.

  When the first kit is used, the method and timing of mixing the first composition and the second composition are not particularly limited as long as the chemical mechanical polishing aqueous dispersion is formed at the time of polishing. For example, the first composition and the second composition may be mixed to prepare the chemical mechanical polishing aqueous dispersion, which may then be supplied to a chemical mechanical polishing apparatus, or the first composition And the second composition may be independently supplied to a chemical mechanical polishing apparatus and mixed on a surface plate. Alternatively, the first composition and the second composition may be independently supplied to the chemical mechanical polishing apparatus and line mixed in the apparatus, or a mixing tank may be provided in the chemical mechanical polishing apparatus. May be mixed within. In line mixing, a line mixer or the like may be used in order to obtain a more uniform aqueous dispersion.

3.2. Second Kit The second kit according to the present embodiment includes (A) an amino acid, (E) a third composition containing ammonia and water, (B) abrasive grains, (C) a surfactant, and A kit for preparing the above-mentioned chemical mechanical polishing aqueous dispersion by mixing these compositions. Further, (D) the oxidizing agent is contained in one or both of the third composition and the fourth composition. Furthermore, the fourth composition may contain (E) ammonia.

  According to the second kit, the storage stability of the abrasive grains contained in the fourth composition can be improved by separately preparing and storing the third composition and the fourth composition. it can. The method for preparing and using the second kit is the same as that for the first kit.

3.3. Third Kit A third kit according to the present embodiment includes (A) an amino acid, (E) a fifth composition containing ammonia and water, (B) abrasive grains, (C) a surfactant, and It consists of a sixth composition containing water and (D) a seventh composition containing an oxidizing agent and water, and these compositions are mixed to prepare the chemical mechanical polishing aqueous dispersion. It is a kit for. (E) Ammonia can be further added to the sixth composition.

  According to the third kit, by separately preparing and storing the fifth to seventh compositions, the abrasive grains contained in the sixth composition and the oxidizing agent contained in the seventh composition Storage stability can be improved. The method for preparing and using the third kit is the same as that for the first kit.

4). Examples Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to these examples.

4.1. Preparation of aqueous dispersion containing abrasive grains 4.1.1. Preparation of Aqueous Dispersion C1 Containing Colloidal Silica Particles 70 parts by mass of ammonia water having a concentration of 25% by mass, 40 parts by mass of ion-exchanged water, 170 parts by mass of ethanol and 20 parts by mass of tetraethoxysilane were charged into a flask at a rotation speed of 180 rpm. The temperature was raised to 60 ° C. with stirring. After stirring while maintaining the temperature at 60 ° C., the mixture was cooled to room temperature to obtain an alcohol dispersion of colloidal silica particles.

  Subsequently, using a rotary evaporator, the operation of removing the alcohol while adding ion-exchanged water was repeated several times. By this operation, alcohol was removed, and an aqueous dispersion “C1” containing 20% by mass of colloidal silica particles was prepared. When the colloidal silica particles contained in the aqueous dispersion C1 were observed using a transmission electron microscope (TEM) (manufactured by Hitachi, Ltd., model “H-7500”), the average primary particle diameter was 25 nm. The average secondary particle size measured using a general light scattering particle size distribution analyzer (manufactured by Horiba, Ltd., model number “SZ-100”) was 50 nm.

4.1.2. Preparation of Aqueous Dispersion C2 Containing Colloidal Silica Particles The amount of ammonia water, ethanol and tetraethoxysilane used in the reaction and the temperature during stirring were varied to obtain colloidal silica particles (average primary particle size 35 nm, average secondary particle size 90 nm). An aqueous dispersion “C2” containing 20% by mass) was prepared.

4.2. Preparation of aqueous dispersion for chemical mechanical polishing 4.2.1. Preparation of Chemical Mechanical Polishing Aqueous Dispersion A When the total weight of the chemical mechanical polishing aqueous dispersion is 100% by mass, 8.8% by mass of glycine and 1.8% of the colloidal silica aqueous dispersion C1 as a solid content are used. After adding ion-exchange water and stirring for 1 hour so that the mass%, ammonium dodecylbenzenesulfonate 0.2 mass%, ammonia 0.85 mass%, and the amount of all the constituents becomes 100 mass%, the pore diameter is 5 μm. A 30% hydrogen peroxide solution in an amount corresponding to 0.45% by mass in terms of hydrogen peroxide was sequentially added to obtain an aqueous dispersion A for chemical mechanical polishing described in Table 1. In addition, the unit of content of each component described in Tables 1 to 3 is mass%, and components other than the components described in the table are water.

4.2.2. Preparation of aqueous dispersions B to Y for chemical mechanical polishing Dispersions B to Y in the same manner as the preparation of aqueous dispersion A for chemical mechanical polishing, except that the additive components were changed to those shown in Tables 1 to 3. Was prepared.

4.3. Examples 1-19, Comparative Examples 1-6
4.3.1. Polishing rate evaluation of copper film A chemical mechanical polishing machine (Applied Materials, model "Mirra") is equipped with a porous polyurethane polishing pad (Rodel Nitta, product number "IC1000"). Then, while supplying any one of the chemical mechanical polishing aqueous dispersions A to Y, the following polishing rate measurement substrate was subjected to a polishing treatment for 30 seconds under the following polishing conditions, and the polishing rate was determined by the following method. Was calculated.

(A) A polishing rate measurement substrate: A blanket wafer in which a copper film is formed on an 8-inch epoxy resin substrate by electrolytic plating.

(B) Polishing conditions / head rotation speed: 90 rpm
・ Platen rotation speed: 87rpm
Head load: 140 g / cm ²
-Supply speed of chemical mechanical polishing aqueous dispersion: 140 mL / min The supply speed of chemical mechanical polishing aqueous dispersion in this case refers to a value obtained by assigning the total supply amount of all the supply liquids per unit time.

(C) Polishing rate calculation method Using an electrically conductive film thickness measuring instrument (model “Omnimap RS75” manufactured by KLA-Tencor), the film thickness of the copper film before and after the polishing treatment is measured and polished to decrease. The polishing rate was calculated from the obtained film thickness and polishing time. The results are shown in Tables 1 to 3.

  The polishing rate of the copper film is preferably 4 μm / min or more. In this case, “◯” is written in the evaluation column in the table. Further, it is particularly preferable that the polishing rate of the copper film is 8 μm / min or more. In this case, “◎” is written in the evaluation column in the table. In addition, when the polishing rate of the copper film is less than 4 μm / min, it is not possible to apply to the printed circuit board, and “x” is written in the evaluation column in the table.

4.3.2. Evaluation of Pattern Wafer Subsequently, each chemical mechanical polishing aqueous dispersion was used to polish a pattern wafer (printed substrate) made of copper and an epoxy resin under the above polishing conditions. This pattern wafer is formed by forming a plurality of wiring recesses with different groove widths on the surface of the base layer made of epoxy resin, and depositing a copper film by electrolytic plating so that each wiring recess is completely filled. It was produced. The groove width of this pattern wafer is 120 μm and 10 μm, respectively. Then, the pattern wafer was polished under the above polishing conditions, and the polishing time until the epoxy resin in portions other than the wiring recesses was completely exposed was determined as “printed substrate processing time”. The dishing value at a groove width of 120 μm was determined based on the following method. Furthermore, the presence or absence of corrosion on the polished surface after polishing was also evaluated. These evaluation results are shown in Tables 1 to 3.

(A) Printed circuit board processing time In the blanket wafer evaluation described above, only the polishing rate of the copper film can be evaluated. However, even when a chemical mechanical polishing aqueous dispersion that exhibits an equivalent polishing rate in a blanket wafer is used, a difference may occur in the processing time of the printed circuit board. In this “printed circuit board processing time”, the polishing time close to the actual manufacturing process is evaluated.

  The printed circuit board processing time is desirably as short as possible, but is preferably 15 minutes or less. In this case, “◯” is shown in the evaluation column in the table. Further, it is particularly preferable that the processing time of the printed circuit board is 6 minutes or less. In this case, “◎” is written in the evaluation column in the table. Further, when the printed circuit board processing time exceeds 15 minutes, it is not possible to apply to the printed circuit board, and “x” is written in the evaluation column in the table.

(B) Evaluation of dishing The dishing value was evaluated using a stylus type step gauge (manufactured by KLA-Tencor, model “P-10”). The dishing value in the evaluation items in the table is described as the dishing value (μm), which is the amount of dent in the copper wiring measured by the stylus type step gauge for a 120 μm wide line formed on the pattern wafer.

  The dishing value is desirably as small as possible, but is preferably 4 μm or less. In this case, “◯” is written in the evaluation column in the table. Further, the dishing value is particularly preferably 2 μm or less. In this case, “◎” is written in the evaluation column in the table. In addition, when the dishing value exceeds 4 μm, it cannot be applied to the printed circuit board, and “x” is written in the evaluation column in the table.

(C) Evaluation of corrosion It was evaluated by an optical microscope (Olympus Corporation make, model number "MX-50") whether or not corrosion was observed in the copper wiring part. The results are shown in Tables 1 to 3. In the column of evaluation in the table, a case where no corrosion was observed in the visual field was indicated as “◯”, and a case where even a little corrosion was observed was indicated as “x”.

In addition, the abbreviation of the component in a table | surface represents the following components, respectively.
C1: Colloidal silica aqueous dispersion C1 prepared above
C2: Colloidal silica aqueous dispersion C2 prepared above
DBS-A: ammonium dodecylbenzenesulfonate DBS-K: potassium dodecylbenzenesulfonate APS: ammonium persulfate

4.4. Evaluation Results When the chemical mechanical polishing aqueous dispersions of Examples 1 to 19 were used, the polishing rate of the copper film was sufficiently high at 4 μm / min or more. In addition, when the chemical mechanical polishing aqueous dispersions of Examples 1 to 19 were used, the printed circuit board processing time could be 15 minutes or less, the dishing value was 4 μm or less, and corrosion occurred on the copper film. Could also be suppressed. From the above, it was shown that by using the chemical mechanical polishing aqueous dispersion according to the present invention, the copper film can be polished at high speed and flatness, and the occurrence of surface defects of the copper film can be suppressed.

In the chemical mechanical polishing aqueous dispersions of Comparative Examples 1 to 4, both the content ratio (W _A / W _D ) and the content ratio (W _E / W _D ) are both below the specified range. Therefore, it was found that the balance was lost, the polishing rate of the copper film was lowered, and a long time was required for processing the printed circuit board.

In the chemical mechanical polishing aqueous dispersion of Comparative Example 5, both the content ratio (W _A / W _D ) and the content ratio (W _E / W _D ) exceed the specified ranges. Therefore, it was found that the balance was lost, the polishing rate of the copper film was lowered, and a long time was required for processing the printed circuit board.

In the chemical mechanical polishing aqueous dispersion of Comparative Example 6, the content ratio (W _E / W _D ) exceeds the specified range. Therefore, the balance was lost, and the polishing rate of the copper film was sufficiently high, but the flatness was impaired and the occurrence of corrosion was also observed.

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 12 ... Resin film | membrane, 14 ... Recess for wiring, 16 ... Copper film, 42 ... Slurry supply nozzle, 44 ... Slurry, 46 ... Polishing cloth, 48 ... Turntable, 50 ... Printed circuit board, 52 ... Carrier head, 54 ... Water supply nozzle, 56 ... Dresser, 100 ... Object to be processed, 200 ... Chemical mechanical polishing apparatus

Claims (14)

A chemical mechanical polishing aqueous dispersion for polishing a wiring layer made of copper or a copper alloy formed on a printed circuit board,
(A) an amino acid;
(B) abrasive grains;
(C) a surfactant;
(D) an oxidizing agent;
(E) ammonia;
Containing
The content of the amino acid content of _{(W A)} and the oxidizing agent _{(W D)} ratio of _(W A / W _D) is from 6.0 to 50, and the content of the ammonia _(W E) the content of the oxidizing agent _{(W D)} and the ratio of _(W E / W _D) is characterized in that it is a 0.6 to 5.0, chemical mechanical polishing aqueous dispersion and. The chemical mechanical polishing aqueous system according to claim 1, wherein the content (W A) of the amino acid ( _A ) is 3% by mass or more and 18% by mass or less based on the total mass of the chemical mechanical polishing aqueous dispersion. Dispersion. The content (W _E ) of the (E) ammonia is 0.4% by mass or more and 2% by mass or less with respect to the total mass of the chemical mechanical polishing aqueous dispersion. An aqueous dispersion for chemical mechanical polishing.   The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 3, wherein the (A) amino acid is at least one selected from the group consisting of glycine, alanine, and glutamic acid.   The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 4, wherein the (B) abrasive grains are colloidal silica.   The surfactant (C) is at least one selected from the group consisting of potassium dodecylbenzenesulfonate, ammonium dodecylbenzenesulfonate, and dipotassium alkenyl succinate. An aqueous dispersion for chemical mechanical polishing as described in 1.   The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 6, wherein the oxidizing agent (D) is hydrogen peroxide.   The aqueous dispersion for chemical mechanical polishing according to any one of claims 1 to 7, wherein the pH is 7 to 11. A kit composed of a first composition and a second composition for preparing the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 8,
The first composition contains (A) an amino acid, (B) an abrasive, (C) a surfactant, and (E) ammonia,
The second composition is a kit for preparing an aqueous dispersion for chemical mechanical polishing, which contains (D) an oxidizing agent. A kit comprising a third composition and a fourth composition for preparing the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 8,
The third composition contains (A) an amino acid and (E) ammonia,
The fourth composition contains (B) abrasive grains and (C) a surfactant.
The chemical mechanical polishing aqueous dispersion preparation kit, wherein at least one selected from the third composition and the fourth composition contains (D) an oxidizing agent.   The chemical mechanical polishing aqueous dispersion preparation kit according to claim 10, wherein the fourth composition further contains (E) ammonia. A kit comprising a fifth composition, a sixth composition, and a seventh composition for preparing the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 8. Because
The fifth composition contains (A) an amino acid and (E) ammonia,
The sixth composition contains (B) abrasive grains and (C) a surfactant,
The seventh composition is a kit for preparing an aqueous dispersion for chemical mechanical polishing, which comprises (D) an oxidizing agent.   13. The chemical mechanical polishing aqueous dispersion preparation kit according to claim 12, wherein the sixth composition further contains (E) ammonia.   A chemical mechanical polishing comprising a step of polishing a wiring layer made of copper or a copper alloy formed on a printed circuit board using the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 8. Method.

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