JP2010021529A - Water-based dispersion for chemical-mechanical polishing used for manufacturing circuit board, method for manufacturing circuit board, circuit board, and multilayer circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based dispersion for chemical-mechanical polishing which is suitably used for forming a circuit board, in which a wiring layer containing copper or copper alloy is formed on a resin substrate, that is sufficiently high in the speed of polishing copper or copper alloy and that is excellent in the flatness of the obtained circuit board. <P>SOLUTION: The water-based dispersion for chemical-mechanical polishing that is used for forming the circuit board, in which the wiring layer containing copper or copper alloy is formed on the resin substrate, contains an organic acid (A), a nitrogen-containing heterocyclic ring compound (B), an oxidizer (C), and abrasive grains (D). In the concentration M<SB>A</SB>(mass%) of the component (A) to the water-based dispersion for chemical-mechanical polishing and the concentration M<SB>D</SB>(mass%) of the component (D) to the water-based dispersion for chemical-mechanical polishing, the relation of M<SB>A</SB>/M<SB>D</SB>=1 to 20 is satisfied and a pH value is 1 to 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an aqueous dispersion for chemical mechanical polishing used for manufacturing a circuit board, a method for manufacturing a circuit board using the aqueous dispersion, a circuit board, and a multilayer circuit board.

  In recent years, electronic devices have been miniaturized, and further miniaturization and multilayering are required for semiconductor devices constituting the electronic devices and circuit boards for mounting the semiconductor devices. A multilayer circuit board (multilayered circuit board) generally has a three-dimensional wiring structure in which a plurality of circuit boards on which wiring patterns are formed are stacked. When the thickness of the multilayer circuit board or the circuit board is not uniform or the flatness is insufficient, problems such as poor connection may occur when the semiconductor device is mounted. Therefore, the circuit boards of the respective layers constituting the multilayer circuit board have a uniform thickness and a flat surface so that unevenness and bending do not occur when the multilayer circuit board is laminated to form a multilayer circuit board. Need to be formed.

  One of the causes of impairing the flatness of the circuit board is the unevenness of the wiring pattern. Such irregularities often occur when a circuit board is manufactured. As a method of manufacturing a circuit board having a wiring pattern, for example, a recess corresponding to a desired wiring pattern is formed on the surface of the board, a conductive layer is formed on the entire surface by plating, and then the surface side of the board is polished. There is a method in which the conductive layer remains only in the recess. In such a manufacturing method, in the plating step, the thinner the line width of the wiring pattern, the thicker the plating thickness of that part may be, and the distribution of the current during plating occurs due to the density of the wiring of the wiring pattern. Depending on the distribution, the thickness may become non-uniform. For this reason, variations in the initial plating thickness have an effect on the subsequent polishing process, and as a result, the flatness of the circuit board may be impaired. Further, when the circuit board is formed by polishing, a phenomenon called dishing in which the polished surface of the wiring pattern formed on the circuit board becomes concave may occur.

  The polishing step is performed by buffing, for example. Patent Document 1 discloses a polishing method using a roll buff, but uses a roll buff formed by combining hard abrasive grains with a binder to form a cylinder. For this reason, such a polishing method has the disadvantages that the thickness of the circuit board is likely to be uneven, and that the surface of the conductive layer is easily damaged (flatness is impaired). Also, a method using a slurry in buffing has been proposed (see, for example, Patent Document 2). However, this method also has a large difference in polishing speed depending on the material of the surface to be polished, and the technical level is such that extremely high thickness uniformity and surface flatness can be obtained like a circuit board used for a multilayer circuit board. Not yet reached.

JP 2002-134920 A JP 2003-257910 A

  When the polishing process is performed by chemical mechanical polishing, the flatness is better than other polishing methods. However, the conventional chemical mechanical polishing has a low polishing rate. In particular, in order to form a circuit board, since the amount of wiring material to be removed is large, it is necessary to greatly improve the polishing rate of chemical mechanical polishing. As described above, the performance of the chemical mechanical polishing aqueous dispersion used for chemical mechanical polishing of a circuit board not only increases the flatness of the surface to be polished but also increases the polishing rate. .

  One of the objects of the present invention is an aqueous dispersion for chemical mechanical polishing suitably used for forming a circuit board in which a wiring layer containing copper or a copper alloy is provided on a resin substrate, the copper or copper alloy It is an object to provide an aqueous dispersion for chemical mechanical polishing that has a sufficiently high polishing rate and good flatness of the resulting circuit board.

  One of the objects of the present invention is to provide a manufacturing method of a circuit board with good flatness, including a step of performing chemical mechanical polishing, and a manufacturing method having a sufficiently high polishing rate in the step.

  One of the objects of the present invention is to provide a circuit board with good flatness and a multilayer circuit board with good flatness in which a plurality of circuit boards are stacked.

The chemical mechanical polishing aqueous dispersion according to the present invention comprises:
A chemical mechanical polishing aqueous dispersion used for forming a circuit board provided with a wiring layer containing copper or a copper alloy on a resin substrate,
(A) an organic acid;
(B) a nitrogen-containing heterocyclic compound;
(C) an oxidizing agent;
(D) abrasive grains;
Including
In the concentration M _A (% by mass) of the component (A) and the concentration M _D (% by mass) of the component (D) with respect to the chemical mechanical polishing aqueous dispersion, a relationship of M _A / M _D = 1 to 20 is established. Have
The pH value is 1-5.

In the chemical mechanical polishing aqueous dispersion according to the present invention,
Furthermore, it can be M _A = 3-15 (mass%).

In the chemical mechanical polishing aqueous dispersion according to the present invention,
The (A) organic acid may be at least one selected from citric acid, glycine, malic acid, tartaric acid, and oxalic acid.

In the chemical mechanical polishing aqueous dispersion according to the present invention,
The (B) nitrogen-containing heterocyclic compound may be at least one selected from benzotriazole, triazole, imidazole, and carboxybenzotriazole.

In the chemical mechanical polishing aqueous dispersion according to the present invention,
The (C) oxidizing agent may be hydrogen peroxide.

In the chemical mechanical polishing aqueous dispersion according to the present invention,
The (D) abrasive grains may be any one of silica particles, calcium carbonate particles, organic polymer particles, and organic-inorganic composite particles.

A method for manufacturing a circuit board according to the present invention includes:
A step of performing chemical mechanical polishing using the above-described chemical mechanical polishing aqueous dispersion.

  The circuit board according to the present invention is manufactured by the above-described manufacturing method.

  A multilayer circuit board according to the present invention includes a plurality of circuit boards described above.

  According to the chemical mechanical polishing aqueous dispersion, a circuit board in which a wiring layer containing copper or a copper alloy is provided on a resin board can be polished uniformly over the entire circuit board and with a flat surface. Furthermore, according to the chemical mechanical polishing aqueous dispersion, the polishing rate of copper or copper alloy can be made extremely high on the order of μm / min. Further, according to the method for manufacturing a circuit board, the circuit board can be manufactured flat and with high throughput. The circuit board and the multilayer circuit board have a uniform thickness over the entire board and have a flat surface. According to the chemical mechanical polishing aqueous dispersion according to the present invention, it is possible to easily provide a circuit board or a multilayer circuit board that is less prone to problems such as poor connection when a semiconductor device or the like is mounted.

It is sectional drawing which shows typically the process of the manufacturing method of the circuit board of this embodiment. It is sectional drawing which shows typically the process of the manufacturing method of the circuit board of this embodiment. It is sectional drawing which shows typically the process of the manufacturing method of the circuit board of this embodiment. It is sectional drawing which shows typically the process of the manufacturing method of the circuit board of this embodiment. It is sectional drawing which shows typically the example of the circuit board manufactured by the manufacturing method of the circuit board of this embodiment.

  Hereinafter, preferred embodiments according to 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 this embodiment comprises (A) an organic acid, (B) a nitrogen-containing heterocyclic compound, (C) an oxidizing agent, and (D) abrasive grains. And including.

  Hereinafter, each component contained in the chemical mechanical polishing aqueous dispersion according to this embodiment will be described in detail. Hereinafter, the substances (A) to (D) may be abbreviated as components (A) to (D), respectively.

1.1. Organic Acid The chemical mechanical polishing aqueous dispersion according to this embodiment contains (A) an organic acid. (A) One of the functions of the organic acid is to improve the polishing rate when the chemical mechanical polishing aqueous dispersion is applied to polishing of the wiring layer containing copper or copper alloy on the resin substrate. . As the organic acid (A) used in the chemical mechanical polishing aqueous dispersion of the present embodiment, an organic acid having a coordination ability with respect to the surface of the wiring material containing ions or copper or a copper alloy containing the wiring material element is used. Is preferred. (A) The organic acid is more preferably an organic acid having chelate coordination ability.

  Examples of the organic acid used in the chemical mechanical polishing aqueous dispersion of this embodiment include tartaric acid, fumaric acid, glycolic acid, phthalic acid, maleic acid, formic acid, acetic acid, oxalic acid, citric acid, malic acid, malonic acid, and glutaric acid. Examples include acid, succinic acid, benzoic acid, quinolinic acid, quinaldic acid, and amidosulfuric acid. In addition, as the organic acid used in the present invention, amino acids such as glycine, alanine, aspartic acid, glutamic acid, lysine, arginine, tryptophan, aromatic amino acids, and heterocyclic amino acids can also be suitably used. These organic acids can be dissociated into at least one proton (hydrogen ion) and a counter anion (parent ion) in the chemical mechanical polishing aqueous dispersion. The chemical mechanical polishing aqueous dispersion of the present embodiment may contain the above-mentioned organic acid alone, or may contain two or more of the above-mentioned organic acids. Among these organic acids, since the effect of improving the polishing rate of the chemical mechanical polishing aqueous dispersion is high, at least one selected from citric acid, glycine, malic acid, tartaric acid and oxalic acid is particularly preferable. .

  The organic acid used in the chemical mechanical polishing aqueous dispersion of the present embodiment is dissolved in the chemical mechanical polishing aqueous dispersion, and a cation derived from another component optionally added, such as ammonium ion, It may be paired with potassium ions or the like. In this case, a salt is formed when the chemical mechanical polishing aqueous dispersion is dried. In this case, the paired cation may be monovalent or more.

  The content of the (A) organic acid in the chemical mechanical polishing aqueous dispersion of this embodiment is 3 to 15% by mass with respect to the mass of the chemical mechanical polishing aqueous dispersion in use as the whole (A) organic acid. It is. The content of (A) the organic acid is more preferably 3.5 to 12% by mass, and particularly preferably 4 to 10.5% by mass. (A) If the content of the organic acid is less than the above range, a sufficient polishing rate may not be obtained, and it may take a long time to complete the polishing step. On the other hand, when the content of the organic acid (A) exceeds the above range, the chemical etching effect is increased, and the wiring layer may be corroded or the flatness of the surface to be polished may be impaired.

1.2. Nitrogen-containing heterocyclic compound The chemical mechanical polishing aqueous dispersion according to this embodiment contains (B) a nitrogen-containing heterocyclic compound. (B) One of the functions of the nitrogen-containing heterocyclic compound is to form a water-insoluble complex with a metal such as copper and to protect the surface of the surface to be polished, thereby increasing the flatness of the surface to be polished. It is done. (B) As a nitrogen-containing heterocyclic compound, the nitrogen-containing heterocyclic compound which has a coordination ability with respect to the surface of the wiring material containing the ion which consists of a wiring material element, or copper or a copper alloy is preferable. (B) A nitrogen-containing heterocyclic compound having chelate coordination ability is more preferable as the nitrogen-containing heterocyclic compound.

  The (B) nitrogen-containing heterocyclic compound suitably used in the chemical mechanical polishing aqueous dispersion according to this embodiment is a compound containing at least one nitrogen as a hetero atom among the heterocyclic compounds. The nitrogen-containing heterocyclic compound is an organic compound containing at least one heterocyclic ring selected from the group consisting of a heterocyclic 5-membered ring and a heterocyclic 6-membered ring having at least one nitrogen atom. Examples of the heterocyclic ring include a hetero five-membered ring such as a pyrrole structure, an imidazole structure, and a triazole structure, and a hetero six-membered ring such as a pyridine structure, a pyrimidine structure, a pyridazine structure, and a pyrazine structure. The heterocyclic ring may form a condensed ring. Specifically, indole structure, isoindole structure, benzimidazole structure, benzotriazole structure, quinoline structure, isoquinoline structure, quinazoline structure, cinnoline structure, phthalazine structure, quinoxaline structure, acridine structure and the like can be mentioned. Among the heterocyclic compounds having such a structure, a heterocyclic compound having a pyridine structure, a quinoline structure, a benzimidazole structure, or a benzotriazole structure is preferable. Specific examples of nitrogen-containing heterocyclic compounds include aziridine, pyridine, pyrimidine, pyrrolidine, piperidine, pyrazine, triazine, pyrrole, imidazole, indole, quinoline, isoquinoline, benzoisoquinoline, purine, pteridine, triazole, triazolidine, benzotriazole, carboxy Examples thereof include benzotriazole, and further, derivatives having these skeletons can be exemplified.

  In the chemical mechanical polishing aqueous dispersion according to this embodiment, as the nitrogen-containing heterocyclic compound (B), the above nitrogen-containing heterocyclic compounds can be used singly or in combination of two or more. (B) The nitrogen-containing heterocyclic compound is particularly preferably at least one selected from benzotriazole, triazole, imidazole, and carboxybenzotriazole.

  The content of the (B) nitrogen-containing heterocyclic compound in the chemical mechanical polishing aqueous dispersion of the present embodiment is based on the mass of the chemical mechanical polishing aqueous dispersion in use as the whole (B) nitrogen-containing heterocyclic compound. , Preferably it is 0.05-2 mass%, More preferably, it is 0.1-1 mass%, Most preferably, it is 0.2-0.5 mass%. (B) If the content of the nitrogen-containing heterocyclic compound is less than the above range, the flatness of the polished surface may be impaired. (B) When content of a nitrogen-containing heterocyclic compound exceeds the said range, a polishing rate may fall.

1.3. (C) Oxidizing agent The chemical mechanical polishing aqueous dispersion according to this embodiment contains (C) an oxidizing agent. (C) One of the functions of the oxidizing agent is to improve the polishing rate when the chemical mechanical polishing aqueous dispersion is applied to polishing a circuit board on which a wiring layer containing copper or a copper alloy is formed. Is mentioned. The reason for this is that (C) the oxidizing agent oxidizes the surface of copper or the like and promotes a complexing reaction with the components of the chemical mechanical polishing aqueous dispersion, thereby forming a fragile modified layer on the surface of copper or the like. It is thought that it is formed to facilitate polishing of copper or the like.

  Examples of the oxidizing agent (C) used in the chemical mechanical polishing aqueous dispersion of the present embodiment include hydrogen peroxide, peracetic acid, perbenzoic acid, organic peroxides such as tert-butyl hydroperoxide, potassium permanganate, and the like. Permanganic acid compounds, dichromic acid compounds such as potassium dichromate, halogen acid compounds such as potassium iodate, nitric acid compounds such as nitric acid and iron nitrate, perhalogenous compounds such as perchloric acid, and ammonium persulfate. Examples thereof include sulfates and heteropolyacids. Of these oxidizing agents, in view of oxidizing power, corrosiveness to resin substrates, and ease of handling, persulfates such as hydrogen peroxide, organic peroxide, or ammonium persulfate are preferred, and decomposition products are preferred. Particularly preferred is hydrogen peroxide which is harmless.

  The content of the (C) oxidizing agent in the chemical mechanical polishing aqueous dispersion of the present embodiment is preferably 1 to 30% by mass, more preferably based on the mass of the chemical mechanical polishing aqueous dispersion in use. It is 5-20 mass%, Most preferably, it is 5-15 mass%. (C) When content of an oxidizing agent is less than the said range, a chemical effect may become inadequate and a grinding | polishing speed | rate may fall, and it may require much time to complete | finish a grinding | polishing process. On the other hand, if the content of (C) the oxidizing agent exceeds the above range, the surface to be polished may corrode and flatness may be impaired, and the polishing rate may be reduced.

1.4. (D) Abrasive Grain The chemical mechanical polishing aqueous dispersion according to this embodiment includes (D) abrasive grains. Examples of (D) abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles.

  Examples of the inorganic particles include silica particles, alumina particles, titania particles, zirconia particles, ceria particles, calcium carbonate particles, and the like.

  The silica particles include fumed silica synthesized by the fumed method in which silicon chloride and the like are reacted with oxygen and hydrogen in the gas phase, silica synthesized by the sol-gel method synthesized by hydrolytic condensation from metal alkoxide, and purification. And colloidal silica synthesized by an inorganic colloid method or the like from which impurities have been removed. In particular, the silica particles are preferably colloidal silica synthesized by an inorganic colloid method in which impurities are removed by purification.

  When silica particles are used as (D) abrasive grains in the chemical mechanical polishing aqueous dispersion of the present embodiment, it is preferable to use colloidal silica having an average particle diameter of 200 nm or less because the flatness becomes good.

  The calcium carbonate particles are preferably high-purity calcium carbonate particles obtained by reacting carbon dioxide after purifying calcium hydroxide in water.

  Organic particles include polyethylene, polypropylene, poly-1-butene, olefin copolymers such as poly-4-methyl-1-pentene, polystyrene, styrene copolymers, polyvinyl chloride, polyacetal, saturated polyester, polyamide , Organic polymer particles such as polycarbonate, phenoxy resin, polymethyl methacrylate, (meth) acrylic resin, and acrylic copolymer.

  The organic / inorganic composite particles can be composed of the organic particles and the inorganic particles. The organic-inorganic composite particles may be any particles as long as the organic particles and the inorganic particles are integrally formed to such an extent that they are not easily separated during the chemical mechanical polishing step, and the types and configurations of the particles are particularly limited. Not. Examples of the organic / inorganic composite particles include polycondensation of alkoxysilane, aluminum alkoxide, titanium alkoxide and the like in the presence of polymer particles such as polystyrene and polymethyl methacrylate, and at least the surface of the polymer particles is polysiloxane, What a polycondensate, such as aluminoxane and a poly titanoxane, couple | bonds together can be used. The produced polycondensate may be directly bonded to the functional group of the polymer particles, or may be bonded via a silane coupling agent or the like. Further, silica particles, alumina particles, or the like can be used instead of alkoxysilane or the like. In this case, the organic-inorganic composite particles are formed such that silica particles are present on the surface of the polymer particles using a polycondensate such as polysiloxane, polyaluminoxane, polytitanoxane or the like as a binder. These may be held in entanglement with polysiloxane or the like, or may be chemically bonded to the polymer particles by a functional group such as a hydroxyl group which they have.

  The organic-inorganic composite particles that can be used in the chemical mechanical polishing aqueous dispersion according to this embodiment include an aqueous dispersion containing organic particles having different zeta potentials and inorganic particles, and these particles are electrostatic forces. And those formed by bonding. The zeta potential of organic particles is often negative over the entire pH range or a wide range excluding the low pH range, but by making organic particles having a carboxyl group, a sulfonic acid group, etc., the negative potential is more reliably reduced. Organic particles having a zeta potential can be obtained. Moreover, it can also be set as the organic particle which has a positive zeta potential in a specific pH range by setting it as the organic particle which has an amino group etc. On the other hand, the zeta potential of inorganic particles is highly pH-dependent and has an isoelectric point at which this potential becomes 0, and the sign of the zeta potential is reversed before and after that. Therefore, by combining specific organic particles and inorganic particles and mixing them in a pH range in which the zeta potential has an opposite sign, the organic particles and the inorganic particles can be integrally combined by electrostatic force. Further, even when the zeta potential has the same sign during mixing, the organic particles and the inorganic particles can be integrated by changing the pH and changing the zeta potential to the opposite sign.

  Furthermore, as the above organic-inorganic composite particles, alkoxysilane, aluminum alkoxide, titanium alkoxide and the like are polycondensed as described above in the presence of particles integrally combined by electrostatic force, and at least on the surface of the particles, Further, a compound obtained by combining polysiloxane or the like can also be used.

  Among the above-mentioned abrasive grains, the abrasive grains used in the chemical mechanical polishing aqueous dispersion according to this embodiment are at least one selected from silica particles, calcium carbonate particles, organic polymer particles, and organic-inorganic composite particles. Preferably there is.

  As for the average particle diameter of (D) abrasive grain used for this invention, 20-500 nm is preferable. This average particle diameter can be measured by a laser scattering diffraction measuring instrument or by observation with a transmission electron microscope. If the average particle size is less than 20 nm, a chemical mechanical polishing aqueous dispersion having a sufficiently high polishing rate may not be obtained. When the average particle diameter exceeds 500 nm, a stable aqueous dispersion may not be easily obtained due to sedimentation and separation of the abrasive grains. The average particle diameter of the abrasive grains may be in the above range, but is more preferably 30 to 400 nm, and particularly preferably 40 to 300 nm. When the average particle diameter is within this range, a stable chemical mechanical polishing aqueous dispersion can be obtained in which the polishing rate is high, dishing is sufficiently suppressed, and particles are not easily settled or separated.

The content of the component (D) in the chemical mechanical polishing aqueous dispersion according to this embodiment is arbitrary as long as the quantitative relationship between the component (A) and the component (D) described later is satisfied. It is more preferable that it is 0.5-5 mass% with respect to the mass of the aqueous dispersion for polishing. That is, the concentration _{M D} of the component (D) in the chemical mechanical polishing aqueous dispersion, and more preferably 0.5 to 5 mass%. The content of the component (D) is more preferably 1 to 4.5% by mass, particularly preferably 1.5 to 4% by mass. When the content of the component (D) is less than the above range, a sufficient polishing rate may not be obtained, and it may take a long time to complete the polishing step. On the other hand, if the content of the abrasive grains exceeds the above range, the flatness of the surface to be polished may be insufficient, the cost may increase, and the storage stability of the chemical mechanical polishing aqueous dispersion may be increased. It may not be possible to secure.

1.5. Quantitative relationship between the (A) component and the (D) component of the chemical mechanical polishing aqueous dispersion The chemical mechanical polishing aqueous dispersion according to this embodiment includes the concentrations M _A (mass%) and (D) of the (A) component. ) The component M _D (mass%) has a relationship of M _A / M _D = 1-20. Here, M _A and M _D are the ratios of the mass of the component (A) and the component (D) to the total mass of the chemical mechanical polishing aqueous dispersion. (A) component concentration _{M A} and (D) ratio of the concentration _{M D ingredients,} M A / _{M D is} more preferably M _A / M D = 1 to _10, the M _A / M D = 2 to 8 Further preferred. If the ratio M _A / M _D is less than the above range, dishing of the wiring layer tends to increase, such being undesirable. Further, if the ratio M _A / M _D is less than the above range, since (D) the abrasive grain component is relatively increased, mechanical polishing is excessively performed on the resin substrate. Since the to-be-polished surface of the circuit board provided with the wiring layer containing copper or copper alloy is rough, it is not preferable. In addition, a stable chemical mechanical polishing aqueous dispersion may not be obtained. When the ratio M _A / M _D exceeds the above range, the flatness of the surface to be polished may be insufficient. Moreover, since corrosion to the wiring metal may occur, it is not preferable.

1.6. PH of aqueous dispersion for chemical mechanical polishing
In the chemical mechanical polishing aqueous dispersion according to this embodiment, the pH value of the chemical mechanical polishing aqueous dispersion is 1 to 5. Here, pH refers to a hydrogen ion index, and the value can be measured using a commercially available pH meter or the like. The pH value of the chemical mechanical polishing aqueous dispersion is preferably 1.5 to 4.5, more preferably 2 to 4. When the pH value of the chemical mechanical polishing aqueous dispersion is less than the above range, the flatness of the polished surface may be deteriorated. If the pH value of the chemical mechanical polishing aqueous dispersion exceeds the above range, the polishing rate may decrease.

  The pH value of the chemical mechanical polishing aqueous dispersion varies depending on the amount of the components (A) to (D). Therefore, the type of each component is selected or the blending amount is changed to adjust the pH value within the above range. Further, depending on the types and blending amounts of the components (A) to (D), the pH value may not fall within the above range. In that case, a pH adjuster or the like may be appropriately added to the chemical mechanical polishing aqueous dispersion to adjust the pH value within the above range.

1.7. pH adjuster The chemical mechanical polishing aqueous dispersion of the present embodiment may be mixed with a pH adjuster such as an acid or an alkali, if necessary. One of the functions of the pH adjuster is to adjust the chemical mechanical polishing aqueous dispersion to a desired pH. Thereby, the chemical mechanical polishing aqueous dispersion has a desired pH value, and it is possible to adjust the polishing rate, improve the flatness, and suppress the corrosion of the wiring layer. The pH adjusting agent can be used when the pH of the chemical mechanical polishing aqueous dispersion is outside the range of 1 to 5, and the pH of the chemical mechanical polishing aqueous dispersion is in the range of 1 to 5. Sometimes it can be used to further adjust the pH.

  Examples of the pH adjusting agent include inorganic acids such as sulfuric acid and phosphoric acid as the acid, and alkali metal water such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide as the alkali. Examples thereof include oxides, tetramethylammonium hydroxide (TMAH), organic alkali compounds such as choline, and ammonia. An acid and an alkali may be mix | blended independently and multiple types may be mix | blended. By adding a pH adjuster, the pH is appropriately set so that the abrasive grains can exist stably while taking into consideration the electrochemical properties of the surface to be polished, the dispersibility and stability of the abrasive grains, and the polishing rate. can do. A pH adjuster particularly suitable for the chemical mechanical polishing aqueous dispersion of this embodiment includes ammonia from the viewpoint of improving the polishing rate.

1.8. Other Additives The chemical mechanical polishing aqueous dispersion according to this embodiment may contain various additives as necessary in addition to the above components. Examples of other additives include anticorrosives for wiring materials, antifoaming agents and antifoaming agents that reduce foaming of the slurry.

2. Circuit board manufacturing method, circuit board, and multilayer circuit board A circuit board manufacturing method according to the present embodiment uses a chemical mechanical polishing aqueous dispersion described in "1. Chemical mechanical polishing aqueous dispersion". A step of polishing.

  The chemical mechanical polishing step is performed by introducing the above-described chemical mechanical polishing aqueous dispersion into a general chemical mechanical polishing apparatus. Hereafter, the manufacturing process of a circuit board is concretely demonstrated using drawing. 1 to 5 are cross-sectional views schematically showing an example of a manufacturing process of the circuit board 100 according to the present embodiment. The chemical mechanical polishing step in the method for manufacturing the circuit board 100 according to the present embodiment is a step for polishing a wiring layer made of copper or a copper alloy.

  As the resin substrate 10 used in the method for manufacturing the circuit board 100 according to the present embodiment, it is only necessary to have insulation at the portion where the wiring layer is formed. For example, a film substrate or a plastic substrate can be used. Can also be used. The resin substrate 10 may be a single-layer body or a laminate in which a resin layer is formed on a substrate made of another material such as silicon.

  As shown in FIG. 1, first, a resin substrate 10 is prepared. The resin substrate 10 is provided with a recess 12 by techniques such as photolithography and etching. The recess 12 is formed corresponding to the wiring layer of the circuit board 100. At least the surface of the resin substrate 10 on which the concave portion 12 is provided has electrical insulation.

  Next, as shown in FIG. 2, a barrier metal film 20 is formed so as to cover the surface of the resin substrate 10 and the bottom and inner wall surface of the recess 12. The barrier metal film 20 is provided as necessary. The barrier metal film 20 can be made of a material such as tantalum or tantalum nitride, for example. As a method for forming the barrier metal film 20, chemical vapor deposition (CVD) can be applied.

  Next, as shown in FIG. 3, a metal for wiring is deposited so as to cover the surface of the barrier metal film 20 to form a metal film 30. The metal film 30 can be made of copper or a copper alloy. After the chemical mechanical polishing process, the metal film 30 remains in the recess 12 and forms a wiring layer of the circuit board 100. As a method for forming the metal film 30, physical vapor deposition (PVD) such as sputtering and vacuum deposition can be applied.

  Next, as shown in FIG. 4, the excess metal film 30 other than the portion buried in the recess 12 is removed by chemical mechanical polishing using the chemical mechanical polishing aqueous dispersion according to the present embodiment. When the barrier metal film 20 is provided, the above method is continued until the barrier metal film 20 is exposed. After chemical mechanical polishing, it is preferable to remove abrasive grains remaining on the surface to be polished. The removal of the abrasive grains can be performed by a normal cleaning method.

  Finally, as shown in FIG. 5, the surfaces of the barrier metal film 20 and the metal film 30 formed other than the recesses 12 are subjected to chemical mechanical polishing using another chemical mechanical polishing aqueous dispersion for the barrier metal film. To remove.

  The circuit board 100 is formed as described above. The circuit board 100 can have a wiring layer having an arbitrary shape. And the multilayer circuit board of this embodiment can be formed by laminating | stacking the some circuit board which has a wiring layer of a suitable shape. The multilayer circuit board can have a three-dimensional wiring structure by appropriately connecting the wiring layers of the circuit boards.

  In the chemical mechanical polishing step of the present embodiment, the metal film 30 is removed using the chemical mechanical polishing aqueous dispersion of the present embodiment, so that the polishing rate is high, the in-plane flatness of polishing is good, dishing, etc. It is difficult to cause selective polishing. Therefore, according to the circuit board manufacturing method of the present embodiment, the circuit board 100 having excellent in-plane flatness can be manufactured with high throughput.

  The circuit board 100 manufactured by the manufacturing method of this embodiment has high in-plane flatness and small dishing. Therefore, the multilayer circuit board formed by stacking the circuit boards 100 of the present embodiment has a uniform thickness over the entire board and has a flat surface.

3. Examples and Comparative Examples Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

3.1. Production of evaluation substrate 3.1.1. Preparation of flatness evaluation substrate Spinning WPR-1201 varnish (manufactured by JSR Corporation; photosensitive insulating resin composition) on a copper-clad laminate (substrate thickness: 0.6 mm, size: 10 cm square) whose surface has been roughened. It was coated and heated on a hot plate at 110 ° C. for 3 minutes to produce a uniform coating film having a thickness of 10 μm. Then, using an aligner (manufactured by Karl Suss, “MA-100”), ultraviolet rays from a high-pressure mercury lamp were irradiated through a pattern mask having a wiring portion of L / S = 100 μm / 100 μm and a pad portion of 2 mm × 2 mm. . The exposure to ultraviolet rays was such that the exposure amount at a wavelength of 350 nm was 3,000 to 5,000 J / m ² . Subsequently, it was heated at 110 ° C. for 3 minutes (PEB) on a hot plate, subjected to immersion development at 23 ° C. for 60 seconds using an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution, and then 120 ° C. in a convection oven. * 2 hours of heating was performed to form a cured insulating resin film having a groove pattern on the copper-clad laminate. A copper seed layer was formed on the obtained cured cured resin film by electroless plating, and then a 10 μm copper plating layer was formed by electrolytic plating. In this way, a flatness evaluation substrate in which copper was embedded in the groove pattern was obtained. If this substrate is properly chemically and mechanically polished, if the copper outside the groove pattern is removed, a circuit substrate having a conductive layer line of 100 μm width and a conductive layer line of 2 mm width is formed.

3.1.2. Preparation of Copper Polishing Rate Evaluation Substrate A substrate with a 10 μm copper plating layer was obtained in the same manner as in “3.1.1. Preparation of flatness evaluation substrate” except that the insulating resin layer groove pattern was not formed.

3.2. Preparation of abrasive dispersion 3.2.1. Preparation of Aqueous Dispersion Containing Fumed Silica Particles 2 kg of fumed silica particles (trade name “Aerosil # 90” manufactured by Nippon Aerosil Co., Ltd.) are dispersed in 6.7 kg of ion-exchanged water using an ultrasonic disperser, and the pore diameter is 5 μm. A water dispersion containing fumed silica was prepared.

3.2.2. Preparation of Water Dispersion Containing Colloidal Silica A 2 liter flask was charged with 70 g of 25% by mass ammonia water, 40 g ion exchanged water, 175 g ethanol and 21 g tetraethoxysilane, and stirred at 180 rpm at 60 ° C. The temperature was raised and stirring was continued for 2 hours at this temperature, followed by cooling to obtain a colloidal silica / alcohol dispersion having an average particle diameter of 70 nm. Subsequently, the operation of removing the alcohol content while adding ion-exchanged water to the dispersion at a temperature of 80 ° C. by an evaporator was repeated several times, the alcohol content in the dispersion was removed, and the solid content was 8% by mass. An aqueous dispersion was prepared.

3.3. Preparation of Chemical Mechanical Polishing Aqueous Dispersion A predetermined amount of the aqueous dispersion described in the section “3.2. Preparation of Abrasive Grain Dispersion” was put into a polyethylene bottle having a capacity of 1 liter. The compounds described in 1) were added so as to have respective contents, followed by thorough stirring. Thereafter, phosphoric acid, tetramethylammonium hydroxide (TMAH), ammonia and potassium hydroxide were added to the dispersions indicated by ◯ in Table 1 as pH adjusters, and the pH was adjusted to the value shown in Table 1. Then, it filtered with the filter of the hole diameter of 5 micrometers, and obtained the aqueous dispersion for chemical mechanical polishing of Examples 1-9 and Comparative Examples 1-4.

3.4. Polishing of substrate A substrate with a copper film without a wiring pattern using the aqueous dispersions of Examples 1 to 9 and Comparative Examples 1 to 4, and a substrate for flatness evaluation in which copper is embedded in the groove pattern described above are as follows: Polished with.

Polishing device: Lapmaster LM15
・ Polishing pad: IC1000 (made by Nitta Haas)
-Carrier head load: 280 hPa
・ Surface plate rotation speed: 90rpm
・ Abrasive supply amount: 100ml / min

  The copper polishing rate was calculated using the following calculation formula from the polishing result of the substrate with a copper film without a wiring pattern. The polishing rate of each example and comparative example is shown in Table 1.

Polishing speed (μm / min) = polishing amount (μm) / polishing time (min)
The polishing amount was calculated using the following equation, assuming that the density of copper was 8.9 g / cm ³ .

Polishing amount (μm) = {(weight before polishing (g) −weight after polishing (g)) / (substrate area (cm ² ) × copper density (g / cm ³ ))} × 10 ⁴
When the value of the polishing rate is 5 μm / min or more, it can be said that the polishing rate is good.

3.5. Evaluation of dishing If an initial surplus film having a thickness T (nm) in which a wiring material is deposited in a recess or the like is polished at a polishing rate V (nm / min), the object is to polish by the time of T / V (min) originally. Should be able to be achieved. However, in the actual manufacturing process, excessive polishing (over polishing) exceeding T / V (min) is performed in order to remove the wiring material remaining in portions other than the recesses. At this time, the wiring portion may be excessively polished, resulting in a concave shape. Such a concave wiring shape is called “dishing” and is not preferable from the viewpoint of reducing the yield of manufactured products. Therefore, dishing was taken as an evaluation item in each example and comparative example.

  Evaluation of dishing was performed using the above-mentioned flatness evaluation board | substrate using the stylus type level | step difference meter (The product made by KLA-Tencor, model "P-10"). The polishing time in the dishing evaluation is a value obtained by dividing the initial excess copper film having a thickness T (nm) by the polishing rate V (nm / min) obtained in “3.4. Polishing of Substrate” (T / V) (minutes) multiplied by 1.5 (minutes).

  In the item of dishing in the evaluation items in Table 1, the amount of depression of the copper wiring measured by the surface roughness meter was described as the dishing value (μm). In the table, “* 1” indicates a case where the wiring disappears and measurement is impossible. The dishing values are shown in Table 1 for 100 μm wide lines and 2 mm wide lines formed on the flatness evaluation substrate. For reference, the difference in dishing value between the 100 μm width line and the 2 mm width line is also shown in Table 1. The dishing value is good when it is 1.5 μm or less for a 100 μm width line and good when it is 2.0 μm or less for a 2 mm width line.

3.6. Storage Stability Evaluation of the storage stability of the chemical mechanical polishing aqueous dispersions of each Example and each Comparative Example was carried out by preparing the chemical mechanical polishing aqueous dispersions and then allowing them to stand at room temperature and normal pressure for 60 days. It implemented by observing each dispersion | distribution after placement visually. As an index for evaluating the storage stability, ◎ when there is no change immediately after preparation, ◯ when a slight precipitate is observed, and × when the separation of the components occurs or the supernatant region occurs, The results are shown in Table 1.

3.7. Evaluation Results According to the results of Table 1, in the chemical mechanical polishing aqueous dispersions of Examples 1 to 9, the copper polishing rate is sufficiently high at 6.6 μm / min or more. Further, the dishing of the 100 μm wiring is as small as 1.4 μm or less, and it has been found that it has a good overpolish margin. Further, it was found that the dishing of the 2 mm wiring is as small as 2.0 μm or less and has a good overpolish margin even for the wide wiring. Moreover, the difference in dishing between the 100 μm line and the 2 mm line is 1.0 μm or less, and it was found that the line width dependence of dishing is small. The chemical mechanical polishing aqueous dispersions of Examples 1 to 9 also had good storage stability.

On the other hand, as shown in Table 1, in Comparative Example 1 (M _A / M _D = 0.5) that does not have a relationship of M _A / M _D = 1 to 20, the dishing of the 2 mm wiring was very bad. _In Comparative Example having no relation _{M A / M D = 1~20 2} (M A / M D = 25), dishing was large defects in both 100μm wiring and 2mm wire. In Comparative Example 3 (pH = 0.5) in which the pH value was outside the lower limit of the range of 1 to 5, dishing was extremely large and defective because the wiring disappeared. In Comparative Example 4 (pH = 5.5) in which the pH value deviated from the upper limit of the range of 1 to 5, the polishing rate was insufficient. In Comparative Example 1, the storage stability was also insufficient.

  As described above, the chemical mechanical polishing aqueous dispersion of the example can polish a metal film containing copper or a copper alloy on a resin substrate at a high polishing rate, and ensure and polish the in-plane uniformity of the substrate. It was found that it was possible to suppress variation in flatness in the plane.

DESCRIPTION OF SYMBOLS 10 ... Resin board | substrate, 12 ... Recessed part, 20 ... Barrier metal film, 30 ... Metal film, 100 ... Circuit board

Claims (9)

A chemical mechanical polishing aqueous dispersion used for forming a circuit board provided with a wiring layer containing copper or a copper alloy on a resin substrate,
(A) an organic acid;
(B) a nitrogen-containing heterocyclic compound;
(C) an oxidizing agent;
(D) abrasive grains;
Including
In the concentration M _A (% by mass) of the component (A) and the concentration M _D (% by mass) of the component (D) with respect to the chemical mechanical polishing aqueous dispersion, the relationship of M _A / M _D = 1 to 20 is established. Have
The aqueous dispersion for chemical mechanical polishing having a pH value of 1 to 5. In claim 1,
Furthermore, the chemical mechanical polishing aqueous dispersion, wherein M _A = 3 to 15 (mass%). In claim 1 or claim 2,
The chemical acid polishing aqueous dispersion, wherein the organic acid (A) is at least one selected from citric acid, glycine, malic acid, tartaric acid and oxalic acid. In any one of Claims 1 thru | or 3,
The chemical mechanical polishing aqueous dispersion, wherein the (B) nitrogen-containing heterocyclic compound is at least one selected from benzotriazole, triazole, imidazole, and carboxybenzotriazole. In any one of Claims 1 thru | or 4,
The chemical mechanical polishing aqueous dispersion, wherein (C) the oxidizing agent is hydrogen peroxide. In any one of Claims 1 thru | or 5,
The (D) abrasive grain is an aqueous dispersion for chemical mechanical polishing, which is any one of silica particles, calcium carbonate particles, organic polymer particles, and organic-inorganic composite particles.   A method for manufacturing a circuit board, comprising a step of performing chemical mechanical polishing using the chemical mechanical polishing aqueous dispersion according to claim 1.   A circuit board manufactured by the manufacturing method according to claim 7.   A multilayer circuit board in which a plurality of the circuit boards according to claim 8 are laminated.

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