JP2001026880A - Formation of conductor pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a conductor pattern capable of easily and securely forming a fine-pitched pattern to a prescribed object. SOLUTION: In a method for forming a conductor pattern including a stage in which metallic ions (M+) are held to the surface of an object 1 composed of an organic compd. as the main raw material and a stage in which the held metallic ions (M+) are reduced and precipitated onto the surface of the object 1 and are made to act as a catalyst, the stage in which the metallic ions (M+) are held is executed, after the introduction of a carboxyl group (-COOH) of an organic compd. composing the object 1, by bonding the metallic ions (M+) to carboxylate ions (-COO-) obtd. by making hydrogen ions (H+) free from the carboxyl group (-COOH). Preferably, the introduction of the carboxyl group (-COOH) into the organic compd. is executed by oxidizing the side chains or terminal groups thereof. Furthermore, the oxidation of the side chains or terminal groups or the conversion of the metallic ions (M+) to a catalyst is executed by irradiating the object 1 with laser light using a laser 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a conductive layer on a surface of a desired object, for example, an insulating substrate or a silicon wafer, and more particularly to a technique applicable to the manufacture of a printed wiring board.

[0002]

2. Description of the Related Art In order to realize high-density mounting on a substrate in accordance with miniaturization of electronic components, finer pitches of conductor patterns formed on a printed wiring board have been developed. On the other hand, it is required to establish a technique for forming a highly reliable conductor pattern by adopting inexpensive materials and simple processes, thereby being advantageous in cost.

As a method of forming a conductor pattern on a substrate, for example, JP-A-61-104083, JP-A-63-304693, or Patent No. 2740
No. 764 discloses a method using electroless plating.

[0004] The invention described in Japanese Patent Application Laid-Open No. 61-104083 discloses a method of irradiating a radiant energy beam such as a laser beam to a surface of a predetermined object in a liquid, for example, to locally raise the temperature of the object. After selectively activating only a desired portion of the product, electroless plating is performed only on the active portion.

The invention described in Japanese Patent Application Laid-Open No. 63-304693 discloses a method of irradiating a substrate coated with a photosensitive solution containing a metal salt (metal ion) of silver or copper or a cationically polymerizable compound with high energy rays, After polymerizing cations and forming metal catalyst nuclei (active sites) by reducing metal ions,
This is a method of performing electroless plating only on the active site.

[0006] The method described in Japanese Patent No. 2,740,764 discloses a method in which a polymer molded article is irradiated with an ultraviolet laser beam to generate a surface potential on the molded article, and a palladium colloid solution having a potential opposite to the surface potential is generated. In this method, palladium colloid is adhered only to a portion irradiated with an ultraviolet laser beam, activated, and then electroless plating is performed only on the active portion.

[0007]

However, the invention described in Japanese Patent Application Laid-Open No. 61-104083 is a method of activating by a local temperature rise by irradiation of a radiant energy beam. Therefore, when the metal ions of the plating solution are reduced and precipitated in the electroless plating, the catalytic activity of the metal catalyst nucleus cannot be utilized as in the case where the active site is formed as the metal catalyst nucleus. Therefore, it is difficult to reduce and deposit the metal ions of the plating solution with high selectivity and reliably at a desired portion irradiated with the radiant energy beam.

The invention described in Japanese Patent Application Laid-Open No. 63-304693 is a method of irradiating a substrate coated with a photosensitive solution containing metal ions by irradiating a high energy ray to activate the substrate. It is necessary to remove unnecessary photosensitive liquid after irradiation with energy rays, but this removal operation is complicated.

Furthermore, in the method described in Japanese Patent No. 2,740,764, the adhesion of the palladium colloid (metal ion) at the time of activation is achieved by the electrostatic force between the palladium colloid and the object. Because
The adhesion of the palladium colloid to the object is small.
For this reason, there is a concern that the activated palladium colloid may be released from the object when the activated object is washed with water or immersed in a plating solution to remove unnecessary palladium colloid, A situation may occur in which the metal is not properly reduced and precipitated at a desired portion.

The present invention has been devised in view of the above circumstances, and provides a conductor pattern forming method capable of easily and reliably forming a fine-pitch pattern on a predetermined object. Is the task.

[0011]

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems, the present invention takes the following technical means.

That is, the method for forming a conductor pattern provided by the first aspect of the present invention comprises the steps of: holding a metal ion on the surface of an object mainly composed of an organic compound;
Holding the metal ions, reducing and precipitating on the surface of the object, and catalyzing the same, wherein the step of holding the metal ions comprises introducing a carboxyl group into the organic compound. Then, a metal ion is bonded to a carboxylate ion from which a hydrogen ion is released from the carboxyl group.

In this method, a carboxylate ion is used as a method for retaining a metal ion in an object. That is, a metal ion is bound or coordinated to a carboxylate ion by utilizing an ion exchange reaction or the like, so that the object holds the metal ion. The metal ions held by such a method are more strongly retained than the case where the paraffin colloid or the like is adhered to the object by electrostatic force and the metal ions are held on the object in a colloidal state. Is done.

That is, since a carboxyl group is introduced by oxidizing a side chain or a terminal group constituting a polymer, it is needless to say that the carboxyl group is strongly linked to an object. Substantially depends on the binding force between the carboxylate ion and the metal ion. This binding force is usually an ionic bond or a coordination bond, and is obviously larger than the electrostatic binding force of a large particle size colloid. As described above, in the holding method in which a carboxyl group is introduced and a metal ion is bonded to the carboxylate ion, the metal ion can be more firmly introduced into a desired portion of the substrate.

In the above method, since metal ions are introduced by an ion exchange reaction utilizing carboxylate ions, various metal ions can be retained. For example, when an ion exchange reaction is used, a metal ion that can be exchanged with a hydrogen ion of a carboxyl group can be retained. For example, metal ions having a high standard electrode potential such as copper ions, nickel ions, palladium ions, silver ions, and gold ions can be held. Since these metal ions are transition metal ions, they can be used as a reduction catalyst if they are reduced and precipitated as metals. Therefore, in the method of introducing metal ions by an ion exchange reaction using carboxylate ions, etc., since there are many types of metal ions that can be introduced, a metal that can be reduced and precipitated during electroless plating performed later is used. There are many types.

In the above method, the retained metal ions are further reduced and precipitated (catalyzed) as a metal on the surface of the object. If the metal ions are catalyzed in this way, the catalytic activity can be used when performing electroless plating later. Therefore, compared to the method of activating by local temperature rise by laser irradiation, the conductor pattern forming method including the step of catalyzing metal ions can more reliably form a conductor layer by electroless plating. it can.

Here, as a method for introducing a carboxyl group into an organic compound, for example, an object is used from a material containing an organic compound having a side chain or a terminal group which is oxidized to a carboxyl group, and the organic compound is A method of oxidizing a side chain or a terminal group is exemplified. Examples of the side chain or terminal group that is oxidized to a carboxyl group include primary alcohol-based groups, aldehyde groups, and alkyl groups such as methyl groups, and many organic compounds, particularly polymers, have such side chains. It has a chain or a terminal group. Also,
Although the present invention is a method that can be used when manufacturing a printed wiring board, the board generally requires heat resistance. For this reason, as a material containing an organic compound, for example, a thermosetting resin such as an epoxy resin, a polyphenylene ether resin, or a polyimide resin is useful, but the organic compound constituting these resins is also oxidized to form a carboxyl group. Since it has a side chain or a terminal group, it is suitably employed in the present invention.

The side chain or terminal group of the organic compound is oxidized by, for example, applying a solution containing an oxidizing agent to the object or immersing the object in the solution. Examples of the oxidizing agent include a manganese compound, a chromium compound, a lead compound, and a peroxide. Alternatively, the object may be irradiated with laser light, and the energy may be used to oxidize the side chains or terminal groups of the organic compound.

The catalysis (reduction) of the metal ions held in the object is performed, for example, by applying a solution containing a reducing agent to the object or immersing the object in the solution. Examples of the reducing agent include a nonmetal ion, an acid, a lower oxide, a lower oxyacid salt, and a metal having a higher ionization tendency than the metal of the above metal ion.
Alternatively, the object may be irradiated with laser light, and the energy may be used to catalyze metal ions.

When the present invention is applied as a technique for forming a pattern on a printed wiring board, a fine pitch of the pattern is required. Therefore, oxidation of side chains or terminal groups of an organic compound or catalysis of metal ions ( One of the reactions (reduction) is preferably performed by laser light irradiation. That is, in the laser, because of its high convergence property,
Because the irradiation spot of the laser beam can be narrowed down,
By using a laser, the width of the region where the carboxyl group is formed or the region where the carboxyl group is catalyzed in the object can be reduced, so that a fine pitch of the conductor pattern can be achieved.

Here, various known lasers such as an excimer laser and an argon laser can be used as the laser. A laser capable of oscillating laser light of a desired wavelength may be selected from known lasers according to the type of reaction such as oxidation or reduction and the type of metal ions to be oxidized or reduced.

Further, according to a second aspect of the present invention, a step of holding metal ions on the surface of a predetermined object, and a step of reducing and depositing the held metal ions on the surface of the object to catalyze the metal ions And, a conductive pattern forming method comprising: holding the metal ions on the surface of the object is performed by attaching a metal complex to the surface of the object,
A method for forming a conductor pattern is provided, wherein the metal ion is catalyzed by irradiating the object with laser light.

Also in this method, since a laser is used for catalyzing metal ions, it is needless to say that fine pitch of the conductor pattern can be achieved.

Since the metal complex bonded to the object is irradiated with a laser to reduce the metal ions and catalyze the metal complex, the bonding force of the catalyst nucleus to the object is changed by the electric force using the surface potential to the colloid. Becomes stronger than when activated by binding. Therefore, the conductor layer can be formed reliably and with a high adhesive force. In addition, if the retention of metal ions on the surface of the target object is performed by binding a metal complex, it is not necessary to introduce a carboxyl group into the target object. The method according to the second aspect of the present invention can be applied to an object mainly composed of an inorganic compound.

When an object composed of an inorganic compound is used, the retention of metal ions on the object is
After the surface of the object is subjected to the coupling treatment, it is preferable to perform the treatment by attaching a metal colloid containing a metal complex. In this way, even for an inorganic compound to which a metal complex is unlikely to adhere, metal ions are reliably held,
A conductor pattern can be formed.

The metal colloid may be attached to the object in a solution state, or may be attached to the object in a gel state. As the coupling agent, a silane-based one is preferably used, and as the metal complex, a carboxylic acid such as malic acid, tartaric acid, citric acid, or gluconic acid is used as a complexing agent for transition metal ions. Those that have been used are preferably used.

[0027] Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIGS. 1A to 1D are schematic views showing each step of the first embodiment of the conductor pattern forming method according to the present invention. In the present embodiment, a case where a conductor pattern is formed on the surface of a substrate mainly composed of an organic compound having a side chain or a terminal group which is oxidized to a carboxyl group will be described.

The method for forming a conductor pattern according to the first embodiment of the present invention comprises a pretreatment of a substrate, an oxidation treatment of a substrate, an ion exchange treatment, a catalyzing treatment, a cleaning treatment, and an electroless plating treatment.

In the pretreatment of the substrate, for example, washing with water,
Surface roughening and surface cleaning are performed. Surface roughening is a process for increasing the adhesion of a metal deposited in a catalyzing process or an electroless plating process performed later to a substrate, for example, a machine using a chemical method such as wet etching or blasting. This is done by a technical method. The surface cleaning is a process for removing dust and oily dirt adhering to the surface of the substrate, and is performed using, for example, an organic solvent, an acidic or alkaline degreasing agent.

Next, the substrate is washed with water and then subjected to an oxidation treatment to introduce a carboxyl group (—COOH) into the organic compound constituting the substrate 1 as shown in FIG. This oxidation treatment is performed by preparing a solution containing an oxidizing agent such as permanganate or chromate, and applying the solution to the surface of the substrate 1 or immersing the substrate 1 in the solution. Will be Then, a part of the side chain or the terminal group of the organic compound constituting the substrate 1 such as a methyl group, an aldehyde group or a primary alcohol is oxidized to a carboxyl group (—COOH).

Further, after the substrate 1 is washed with water, an ion exchange process is performed to hold the metal ions (M ⁺ ) on the substrate 1 as shown in FIG. 1B. Note that FIG. 1B shows a monovalent metal ion as an example. This ion exchange treatment is performed, for example, by preparing a solution containing ions of a transition metal having a standard electrode potential higher than that of hydrogen and applying the solution to the substrate 1, or by immersing the substrate 1 in the solution. Will be Then, the metal ion (M) is added to the carboxylate ion (—COO ⁻ ) in which the hydrogen ion (H ⁺ ) is released from the carboxyl group (—COOH).
⁺ ) Is bonded, and a metal ion (M ⁺ ) is held on the surface of the substrate 1 as a part of a side chain or a terminal group of the organic compound.

Next, after the substrate 1 is washed with water, a catalytic treatment is performed to catalyze the metal ion (M ⁺ ) bonded to the carboxylate ion (—COO ⁻ ). This catalyzing treatment is performed according to the pattern to be formed.
The irradiation is performed by irradiating the substrate 1 with a laser beam such as a laser beam. Then, as shown in FIG. 1C, only the metal ions (M ⁺ ) in the portion of the substrate 1 irradiated with the laser beam are selectively reduced and deposited, and the growth nuclei are formed later in the electroless plating. The catalyst nucleus 3 to be formed is patterned.

Further, after the substrate 1 is washed with water, a cleaning treatment is performed to remove metal ions (M ⁺ ) which have not been reduced by being irradiated with laser light, and to reduce and remove remaining carboxyl groups (-COOH). I do. In this cleaning treatment, metal ions (M ⁺ ) are removed by an aqueous nitric acid solution, and carboxyl groups (—COOH) are reduced by a hydrogen peroxide solution.

Next, after washing the substrate 1 with water, an electroless plating process is performed to form a conductor layer 4 on the catalyst core 3 as shown in FIG. This electroless plating process
A plating solution containing at least a metal ion and a reducing agent and, if necessary, a complexing agent, a pH adjuster and other additives is prepared, and the plating solution is applied to the surface of the substrate 1, or This is performed by immersing the substrate 1 therein. Then, the metal ions are reduced by the action of the reducing agent in the plating solution and the catalyst nuclei 3 on the surface of the substrate 1, and the conductor layer 4 is selectively formed with respect to the portion of the catalyst nuclei 3. In this manner, electroless plating is selectively performed only on desired portions of the substrate 1 to form conductor patterns.

Next, a second embodiment of the conductor pattern forming method according to the present invention will be described with reference to FIGS. 2 (a) to 2 (d). In the present embodiment, a method of forming a conductor pattern on a substrate whose main material is an organic compound having a side chain or a terminal group that is oxidized to a carboxyl group will be described.

As in the first embodiment, the method according to the present embodiment includes a pretreatment, an oxidation treatment, an ion exchange treatment, a catalyzing treatment, a cleaning treatment, and an electroless plating treatment. The pretreatment, the ion exchange treatment, the cleaning treatment, and the electroless plating treatment are performed in the same manner as the method according to the first embodiment, and the oxidation treatment and the catalysis treatment are performed by different methods.

Specifically, first, after performing the pretreatment in the same manner as in the first embodiment, the substrate is washed with water, and a predetermined oxidation treatment is performed. This oxidation treatment is performed by irradiating a portion of the surface of the substrate 1 where a conductor pattern is to be formed with a laser beam using an excimer laser 2 or the like as shown in FIG. Then, among the side chains or terminal groups of the organic compound constituting the substrate 1, only those which are irradiated with laser light and oxidized to a carboxyl group (-COOH) are selectively carboxyl groups (-COOH).
Becomes That is, a carboxyl group (—COO) is formed on the surface of the substrate 1 in accordance with the trajectory scanned by the laser beam.
H) are lined up to be in a patterned state.

Next, after the substrate 1 is washed with water, an ion exchange treatment is performed in the same manner as in the first embodiment.
As shown in carboxylate ion (-COO ^-)
After a metal ion (M ⁺ ) is bound to the metal, a predetermined catalytic treatment is performed. FIG. 2B shows a monovalent metal ion as an example. This catalyzing treatment is performed by preparing a solution containing a reducing agent such as sodium borohydride and applying the solution to the surface of the substrate 1 or by immersing the substrate 1 in the solution. Then, the metal ion (M ⁺ ) bonded to the carboxylate ion (—COO ⁻ ) is reduced and deposited on the surface of the substrate 1 to form the catalyst core 3 as shown in FIG. 2C. Since the carboxyl group (—COOH) is introduced in a patterned state on the surface of the substrate 1 by irradiation with one laser beam, the catalyst nucleus 3 is also formed in a patterned state.

Further, after the substrate 1 is washed with water, a washing process and an electroless plating process are performed in the same manner as in the first embodiment. In the present embodiment, since the catalyst nucleus 3 is patterned, if electroless plating is performed, the conductor layer 4 is patterned according to the pattern of the catalyst nucleus 3 as shown in FIG.

FIGS. 3A to 3C schematically show the steps of the third embodiment of the conductor pattern forming method according to the present invention. In the present embodiment, an inorganic compound is used as a main raw material. A case where a conductor pattern is formed on a substrate will be described.

The method of forming a conductor pattern according to the present embodiment includes a pretreatment of a substrate, a colloid treatment, a catalyzing treatment, a cleaning treatment, and an electroless plating treatment.

In the pretreatment of the substrate, water washing, surface roughening, surface cleaning, and the like are performed, and the surface treatment is performed as necessary. Surface roughening and surface cleaning are performed in the same manner as in the first embodiment. The surface treatment is a treatment performed so that the metal colloid easily adheres to the substrate, for example, by a coupling treatment using a silane coupling agent. Of course, the irradiation may be performed by irradiating ultraviolet rays to generate a potential on the surface of the substrate.

Next, the substrate is washed with water and then subjected to a colloid treatment to hold metal ions (M ^{n +} : n is a positive integer) on the surface of the substrate 1 as shown in FIG. This colloid treatment is performed by mixing a solution containing a desired metal ion (M ^{n +} ) with a complexing agent to prepare a colloid solution, and applying the colloid solution to the substrate 1 or by adding the substrate to the colloid solution. 1 is immersed. Then, since the metal colloid (metal complex) adheres to the surface of the substrate 1, the metal ions ( ^{Mn +} ) are held in the state of the metal colloid. Note that the colloid solution may be gelled, and the metal colloid may be attached to the surface of the substrate 1.
As the metal ion (M ^{n +} ), a transition metal ion such as a copper ion, a silver ion or a palladium ion is preferably used, and as the complexing agent, a carboxylic acid such as malic acid, tartaric acid or citric acid is preferable. used.

Further, after the substrate 1 is washed with water, a catalytic treatment is performed to catalyze metal ions (M ^{n +} ) in the metal colloid. This catalyzing treatment is performed by irradiating a laser beam while scanning the surface of the substrate 1 with a laser beam by an excimer laser 2 or the like, as shown in FIG. 3B. . Then, the metal ions (M ^{n +} ) in the colloid are reduced and deposited on the surface of the substrate 1 at the portion irradiated with the laser light, and the catalyst nuclei 3 are patterned.

Next, after the substrate 1 is washed with water, a cleaning process is performed. In this cleaning treatment, the gold colloid in which the metal ions have not been reduced is removed by, for example, an aqueous nitric acid solution.

Further, after the substrate 1 is washed with water, an electroless plating process is performed in the same manner as in the first embodiment, so that a desired conductive layer 4 is formed on the surface of the substrate 1 as shown in FIG. Is patterned.

[0049]

As described above, according to the present invention, a fine-pitch pattern can be easily and reliably formed on a predetermined object.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating each step of a first embodiment of a conductor pattern forming method according to the present invention.

FIG. 2 is a schematic view illustrating each step of a second embodiment of the method for forming a conductor pattern according to the present invention.

FIG. 3 is a schematic view illustrating each step of a third embodiment of the conductive pattern forming method according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2 Laser 3 Catalyst core 4 Conductive layer M ⁺ , ^{Mn +} metal ion

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K022 AA42 BA35 CA03 CA06 CA07 CA12 CA15 CA19 CA20 CA21 CA23 DA01 5F033 HH07 HH11 HH13 HH14 PP28 PP31 QQ53 QQ54 QQ89 RR21 RR22

Claims (6)

[Claims] 1. A step of holding a metal ion on the surface of an object using an organic compound as a main raw material, and a step of reducing and depositing the held metal ion on the surface of the object to catalyze the metal ion. In the method for forming a conductor pattern, the step of retaining the metal ion comprises: introducing a carboxyl group into the organic compound, and then bonding the metal ion to a carboxylate ion from which a hydrogen ion has been released from the carboxyl group. A conductive pattern forming method, which is performed. 2. The organic compound has a side chain or a terminal group which is oxidized to a carboxyl group, and
The carboxyl group is introduced into the organic compound by oxidizing a side chain or a terminal group thereof.
3. The method for forming a conductor pattern according to item 1. 3. The conductive pattern forming method according to claim 2, wherein the oxidation of the side chain or the terminal group of the organic compound is performed by irradiating the object with laser light. 4. The method according to claim 1, wherein the catalysis of the metal ions held by the object is performed by irradiating the object with laser light. 5. A conductive pattern forming method comprising: a step of retaining metal ions on a surface of a predetermined object; and a step of reducing and depositing the retained metal ions on the surface of the object to catalyze the metal ions. The retention of metal ions on the surface of the object is performed by attaching a metal complex to the surface of the object, and the catalysis of the metal ions is performed by irradiating the object with laser light. A conductive pattern forming method. 6. The object has an inorganic compound as a main raw material, and retains metal ions on the object.
The conductor pattern forming method according to claim 5, wherein the method is performed by attaching a metal colloid containing the metal complex after the surface of the object is subjected to a coupling treatment.