WO2007141883A1

WO2007141883A1 - Method of forming electrical wiring and method of repairing the same

Info

Publication number: WO2007141883A1
Application number: PCT/JP2006/311686
Authority: WO
Inventors: Masato Ikeda
Original assignee: Kabushiki Kaisha Nihon Micronics
Priority date: 2006-06-06
Filing date: 2006-06-06
Publication date: 2007-12-13
Also published as: JPWO2007141883A1; TW200820856A

Abstract

It is intended to provide a method of forming an electrical wiring, in which a paste material containing metal nanoparticles, a binder comprising an organic compound is applied on an insulating substrate thereby to form a pattern portion for wiring. Then, on the pattern portion formed with the paste material, oxygen radical molecules are sprayed. By this spraying of oxygen radical molecules, the organic compound in the binder is oxidized and released in the atmosphere, and then the metal nanoparticles directly come into contact with one another, whereby sintering occurs due to the resulting high surface energy. By the sintering due to the mutual contact of metal nanoparticles, a conductive portion is formed on the insulating substrate.

Description

Specification '

Electrical wiring formation method and repair method thereof

Technical field

The present invention relates to a method for forming electrical wiring and a repair method therefor, and more particularly to a wiring formation method suitable for a wiring board of an electronic circuit device such as a liquid crystal display device and a semiconductor device and a repair method therefor.

Backkyo technology

As a conventional method for forming an electrode of a flat panel display, there is a method described in Japanese Patent No. 3 5 2 3 2 5 1. According to this method, a film is formed on a glass substrate by using a paste made of an organic binder containing acid silver powder and low-melting glass powder on a glass substrate. When this film is irradiated with a laser along a desired pattern, the binder is removed by heating by laser irradiation, and silver oxide in the film is partially baked on the glass substrate, and then the film is heated. By removing unnecessary portions, an electrode is formed by the baked silver oxide.

Further, according to the method described in International Publication No. WO 2 0 0 2/0 5 2 6 2 7, the work is selectively covered with a mask such as a photoresist. A liquid repellent treatment is applied to the surface of the mask, and then the liquid pattern material is filled into the area exposed from the mask of the workpiece. After the filled liquid pattern material is solidified, the mask is removed, and an electrode pattern is formed by the solidified portion of the liquid pattern material. This publication also describes the use of atmospheric plasma generated by an atmospheric plasma apparatus that converts a fluorine compound into plasma for the formation of a liquid-repellent mask and atmospheric pressure plasma for removal of the mask. However, heat treatment using a heater is used to solidify the liquid pattern material.

As described above, according to the prior art, physical heating using a laser beam or a heater is employed for the formation of the wiring or electrode material, and the organic binder is removed by this physical heating. In addition, the conductive material constituting the wiring or electrode material is fired.

However, with laser irradiation, care must be taken so that unnecessary portions are not irradiated with high-energy laser light, and handling is not easy. Also, Heat treatment using a heater is disadvantageous for electronic circuits that dislike high temperatures, such as semiconductor ICs, because the heating process takes a long time and the entire substrate is exposed to a high temperature atmosphere.

[Patent Document 1] Japanese Patent No. 3 5 2 3 2 5 1

[Patent Document 2] International Publication Number WO 2 0 0 2 Z 0 5 2 6 2 7 Disclosure of Invention

Problems to be solved by the invention

An object of the present invention is to provide a method for forming or repairing electrical wiring efficiently and easily.

Means for solving the problem

The present invention basically does not depend on a physical phenomenon such as heating in order to remove a binder composed of organic substances such as carbon, oxygen, hydrogen and nitrogen contained in a paste material for forming a conductive path. It is characterized by using chemical reaction by oxygen radical.

That is, the present invention is to form a pattern portion for wiring on an insulating substrate with a paste material including nano metal particles and a binder made of an organic substance, and to convert the pattern portion formed with the paste material into an oxygen radical. Characterized by exposure to molecules or their gases.

In the electrical wiring forming method according to the present invention, the paste material containing the nano metal particles is surely adhered onto the insulating substrate along the desired pattern on the insulating substrate due to the viscosity of the organic binder. As a result, a desired pattern portion is formed on the insulating substrate with the paste material. This pattern portion is exposed to oxygen radical molecules or its gas. The oxygen radical molecule is a molecule having an unpaired electron in the outer electron, and causes a chemical reaction with each organic substance in the paste material. Through this chemical reaction, hydrogen in the organic material becomes water, which is evaporated and released into the atmosphere. Carbon also becomes carbon dioxide and is released into the atmosphere. In addition, other organic materials such as oxygen and nitrogen are also released into the atmosphere as gases. When organic binder is removed from the paste material due to the release of this organic material, the nano metal particles with high surface energy By direct contact with each other without going through an organic binder, a metal bond is generated by the surface energy.

As a result, a conductive path is formed by metal bonding between the contact metal particles without using a physical heating phenomenon by a heater or laser light.

In order to expose the organic binder to oxygen radical molecules or its gas, oxygen radical molecules can be injected toward the pattern on the insulating substrate.

The oxygen radical molecule can be formed using a plasma generator. The plasma generator generates a gas in which positive and negative charged particles coexist, and the gas contains radical molecules such as oxygen radicals. Therefore, the organic material of the pattern portion can be exposed to oxygen radical molecules or the gas by injecting the plasma gas generated from the plasma generator toward the pattern portion on the insulating substrate.

In addition, an atmospheric plasma generator can be used as the plasma generator. Since the atmospheric plasma generator can generate oxygen radical molecules at almost atmospheric pressure, the insulating substrate including the pattern portion, that is, the workpiece, is not exposed to vacuum, and is almost exposed to the atmosphere. Radical molecules can be irradiated onto the pattern portion. This eliminates the need for a vacuum chamber for holding the workpiece in a vacuum, so that the conductive path can be formed more easily by using an atmospheric plasma generator. Further, the ratio of radical molecules in the plasma gas can be increased by lowering the temperature of the plasma gas, for example, by cooling. The organic material can be more effectively removed by spraying the gas having an increased proportion of radical molecules on the pattern portion, whereby the conductive portion can be formed more efficiently.

The nano metal particles are metal fine particles such as silver having a particle diameter of several nanometers to several hundred nanometers. Since such metal fine particles have extremely high surface energy, it is possible to generate metal bonds more reliably by simply removing the binder. As such a paste material containing gold or silver fine metal particles and an organic pinder, for example, a product sold by Harima Kasei Co., Ltd. under a trade name of nanopace can be used. ' It is desirable that each of the nano metal particles is covered with a protective film made of an organic material. The protective film reliably prevents unexpected or unnecessary metal bonds due to direct contact between nano metal particles in an unreacted state with radical molecules, and is removed quickly and reliably by irradiation with radical molecules. It enables metal bonding by direct contact between nano metal particles.

The pattern part can be formed on the insulating substrate by spraying the paste material by an ink jet method. In addition, this pattern portion is formed by maskless mesoscale material deposition (M ³ D (trademark)) apparatus (U.S. Pat. No. 7,045,015) manufactured by Optomek, USA. ) Or other printing methods can be employed as appropriate. The above-described forming method of the present invention can also be applied to repair of a wiring path on an insulating circuit board.

The invention's effect

According to the present invention, a binder is removed by utilizing a chemical reaction between an oxygen radical molecule and an organic material of a binder, and a conductive portion such as a conductive path is formed by sintering by contact between nano metal particles by removing the binder. It is formed. Therefore, by heating the pattern portion with oxygen radical molecules for a short time without using laser light in the heating furnace, the temperature of the irradiated portion is suppressed and the binder is removed. Thus, the conductive portion can be formed efficiently. Brief Description of Drawings

FIG. 1 is a flowchart showing the steps of the method of the present invention.

FIG. 2 is a schematic diagram of an apparatus for carrying out the method of the present invention.

FIG. 3 is a cross-sectional view schematically showing the principle of the atmospheric plasma generator used as the purified gas generator shown in FIG.

FIG. 4 is a cross-sectional view schematically showing the principle of the atmospheric plasma generator used as the oxygen radical generator shown in FIG.

FIG. 5 is an explanatory diagram showing the electrical characteristics of the conductive path formed by the method of the present invention. Explanation of symbols

1 0 Wiring forming equipment

1 2 Insulation substrate

1 4 Conduction path (pattern part)

1 6 Air plasma generator for purification

1 8 Paste material applicator

2 0 Oxygen radical molecule injection device (atmospheric plasma generator)

S 1 2 Pattern part formation step

S1 4 Oxygen radical molecule irradiation step BEST MODE

As shown in FIG. 1, the method for forming an electrical wiring according to the present invention includes a step S 10 for preliminarily purifying a portion to be wired on an insulating substrate, and a desired wiring pattern on the insulating substrate. A coating step S 12 for forming a pattern portion with the paste material by applying a paste material along the paste material, and a step S for irradiating the pattern portion formed on the insulating substrate with oxygen radical molecules Including 1 and 4.

In the purification step S 10, as described later, the oxides on the insulating substrate are removed by spraying the purified gas onto the insulating substrate. As the purification step S 10, for example, plasma gas from an atmospheric plasma generator can be used. In the atmospheric plasma generator for purification, a reducing gas such as carbon monoxide gas or hydrogen gas is used as the plasma generating gas. By blowing the plasma gas from the atmospheric plasma generator using such a reducing gas, the oxide remaining in the irradiated part causes a chemical reaction with the plasma gas, and these are effectively removed. In addition, such a plasma gas exhibits a relatively low temperature of 60 ° C. to 80 ° C. at the irradiated portion, and therefore the irradiated portion and its surroundings are not damaged by heating. In this purification step S 10, other appropriate cleaning means can be used instead of the plasma apparatus. Further, the purification step S 10 can be eliminated. However, the adhesion of the paste material to the insulating substrate in the subsequent coating step S 1 2 is increased, and the bonding force of the formed metal wiring to the insulating substrate is further increased. Above, it is desirable to adopt some sort of purification means.

In the applying step S 1 2, a paste material containing nano metal particles and a binder made of an organic material is applied along the desired wiring pattern on the insulating substrate.

The nano metal particles in the paste material are fine metal particles having a particle size of several nanometers to several hundred nanometers and exhibiting good conductivity such as gold or silver. Since such metal fine particles have extremely high surface energy, when the metal particles are in direct contact with each other, this contact causes metal sintering.

In addition to increasing the adhesion of the paste material onto the insulating substrate, the binder in the paste material has an E contact between the nano metal particles in order to prevent unnecessary and unexpected metal sintering. This prevents the metal particles from being sintered. Such a binder is formed of an organic material such as oxygen, carbon, hydrogen and nitrogen, as is well known as an organic binder. Further, in order to enhance the protective action by the binder, it is desirable to cover the surface of each nano metal particle with a binder protective film.

It is desirable to use “Nanobest” sold by Harima Kasei Co., Ltd. as such paste material.

For application of the paste material, the paste material can be sprayed, for example, by a nozzle using an ink jet method. In addition, a paste material can be appropriately applied onto the insulating substrate by the M ³ D (trademark) apparatus or other printing methods. In addition, a selective mask that selectively exposes the desired portion can be used for applying the paste material to the desired portion.

In the oxygen radical molecule irradiation step S 14, the oxygen radical molecule or its gas is sprayed onto the pattern portion made of the paste material applied on the insulating substrate.

The gas containing oxygen radical molecules can be obtained by a plasma generator, for example. The plasma gas is high temperature and is electrically neutral as a whole, but positive and negative charged particles and ion-op radical molecules coexist in the gas. In a plasma gas that contains oxygen radical molecules in the radical molecules, the proportion of oxygen radical molecules is relatively low compared to charged particles and ions. However, when this plasma gas is cooled, The proportion of oxygen radical molecules in the plasma gas increases. Since the present invention basically uses this oxygen radical molecule, it is desirable to use a gas that is cooled and has as high a proportion of oxygen radical molecules as possible.

When the paste material is exposed to an atmosphere of oxygen radical molecules by plasma gas irradiation, a chemical reaction occurs between the oxygen radical molecules and each organic substance. By this chemical reaction, hydrogen in the organic substance becomes water and is released into the atmosphere. Carbon, nitrogen, oxygen, etc. become gas and are similarly released into the atmosphere.

When the organic component of the binder is released and decomposed by a chemical reaction between an organic substance and an oxygen radical molecule, the nano metal particles that have been prevented from direct contact by the binder are brought into direct contact. Since the surface energy of the nano metal particles is extremely high, sintering occurs due to direct mutual contact. As a result, a conductive path is formed on the insulating substrate by sintering the nano metal particles.

FIG. 2 is a schematic view partially showing an example of a wiring forming apparatus 10 for carrying out the above-described wiring forming method of the present invention.

In the example shown in FIG. 2, the wiring forming apparatus 10 is used to form the conductive path 14 along a desired pattern on the insulating substrate 12. The wiring forming apparatus 10 includes a purifier atmospheric plasma generating apparatus 16, a paste material applying apparatus 18, and an oxygen radical molecule injection apparatus 20.

As shown in FIG. 3, the atmospheric plasma generator for clean water 16 has a dielectric material such as glass whose upper end is a gas inlet 2 2 a and whose lower end is a plasma outlet 2 2 b. A dielectric tube 2 2 and a pair of electrodes 2 4, 2 4 arranged so as to cover each other in the longitudinal direction of the dielectric tube and covering a distance d 1, each surrounding the dielectric tube 2 2 And a power supply device 26 for applying an alternating voltage or a pulse voltage between the electrodes. .

At the gas inlet 2 2 a of the dielectric tube 2 2, a reducing gas G 1 such as carbon monoxide gas or hydrogen gas and a carrier gas C a such as nitrogen or argon are conceived through the opening and closing pulp 28. Is possible. As shown in FIG. 2, the dielectric tube 22 has its plasma injection port 2 2 b directed to the surface of the insulating substrate 12 on which the conductive path 14 is to be formed. When the on-off valve 2 8 is opened, the carrier gas C a from the carrier gas source 3 2 and the reducing gas G 1 force from the reducing gas source 3 0 G 1 force Dielectric tube 2 2 內 is turned into its plasma injection port 2 2 b Guided towards. In the flow path of the dielectric tube 2 2 through which the reducing gas G 1 is guided, a pair of electrodes 2 4 and 2 4 to which a voltage from the electrical apparatus 26 is applied corresponds to the distance d 1 between both electrodes. A discharge space region is formed in the region by dielectric barrier discharge. Therefore, the reducing gas G 1 guided from the gas introduction port 2 2 a of the dielectric tube 2 2 toward the plasma injection port 2 2 b is put in a plasma state in the process of passing through this discharge space region. As a result, a plasma gas using the reducing gas G 1 as a plasma source is injected onto the insulating substrate 12.

By the injection of the plasma gas from the dielectric tube 22, the oxide remaining in the portion irradiated with the plasma gas is effectively removed 1 by the chemical reaction with the plasma gas as described above. At this time, in the atmospheric plasma using the reducing gas G 1 as a plasma gas source, the temperature of the irradiated part is maintained at 60 ° C. to 80 ° C. Therefore, the irradiated part on the insulating substrate 1 2 Will not be damaged by heating.

The dielectric tube 2 2 of the atmospheric plasma generator for purification 1 2, that is, the air plasma injection nozzle 2 2, is automatically shown in the desired arrangement and pattern using a well-known automatic control mechanism (not shown). Can be moved to.

The paste material is supplied from the nozzle 3 4 outlet of the paste material application device 18 to the region on the insulating substrate 12 2 purified by the injection of atmospheric plasma gas using the reducing gas G 1 as a gas source. The By making the nozzle 3 4 of this paste material coating device 1 8 follow the nozzle 2 2 of the purification atmospheric plasma generation device 16, the paste material is sequentially applied onto the purified region on the insulating substrate 1 2. Can be supplied linearly.

A wiring pattern portion formed linearly on the insulating substrate 12 by the paste material is irradiated with oxygen radical molecules by the oxygen radical molecule injection device 20. In the example shown in FIG. 4, this oxygen radical molecule injection device 20 basically uses an atmospheric plasma generator similar to the atmospheric plasma generator shown in FIG. The fundamental difference between the two atmospheric plasma generators is that the purifying atmospheric plasma generator 16 uses a reducing gas source 30 as the plasma gas source, while oxygen radical molecule injection The atmospheric plasma generator used as the apparatus 20 is that an oxidizing gas source such as oxygen or air is used as the plasma gas source.

That is, the atmospheric plasma generator 20 used as an oxygen radical molecular jetting apparatus includes a dielectric tube 36 made of a dielectric material such as glass and a longitudinal direction of the dielectric tube, as shown in FIG. A pair of electrodes 3 8 and 3 8 which are arranged with a distance d 2 from each other, and are arranged around the dielectric tube 3 6, and an alternating voltage or a pulsed voltage is applied between the electrodes. Power supply device 40 for performing the operation.

The gas inlet 36a, which is the upper end of the dielectric tube 36, has an open / close valve 42 and an oxygen gas G2 such as oxygen gas or air and a carrier gas Ca such as nitrogen or argon. Guided. As shown in FIG. 2, the dielectric tube 36 has its plasma injection port 36 b directed toward the wiring pattern portion.

When the on-off valve 4 2 is opened, the carrier gas source 4 6 and the carrier gas C a together with the oxidizing gas source G 4 from the oxidizing gas source 4 4 pass through the dielectric tube 3 6 toward its plasma injection port 3 6 b. Guided. In the flow path of the dielectric tube 36 through which the oxygen gas G 2 is guided, there is a region corresponding to d 2 between the pair of electrodes 38 and 38 to which the voltage from the power supply device 40 is applied. A discharge space region is formed by dielectric barrier discharge. Therefore, as in the above-described atmospheric plasma generator 16, the oxidizing gas G 2 guided from the gas inlet 3 6 a of the dielectric tube 3 6 toward the plasma outlet 3 6 b is in this discharge space. In the process of passing through the region, it is put into a plasma state.

When the plasma using the oxygen gas G 2 as a plasma source is sprayed onto the insulating substrate 12, as described above, oxygen radicals contained in the plasma are converted into an organic binder in the paste material of the wiring pattern portion. Cause a chemical reaction. As a result, the organic binder is removed mainly by a chemical reaction with oxygen radicals. When the organic binder is removed from the wiring pattern portion formed of the paste material, the nano metal particles in the wiring pattern portion come into contact with each other. When this mutual contact occurs, the nanometal particles are sintered by the surface energy of the nanometal particles as described above, and the conductive path 14 is formed.

It is possible to cause the dielectric tube or nozzle 36 of the oxygen radical molecular injection device 20 to follow the nozzle at a predetermined interval from the nozzle 34 of the paste material coating device 18. desirable.

In addition, the content of oxygen radical molecules in the plasma gas sprayed from the nozzle 36 of the atmospheric plasma generator 20 using the oxidizing gas G 2 as the plasma gas source is increased, and the temperature rise of the insulating substrate 12 is unnecessary. In order to suppress this, it is desirable to reduce the temperature of the plasma gas flow injected from the plasma injection port 3 6 b of the dielectric tube 36 as much as possible. By setting the temperature of the plasma flow injected from the plasma injection port 36 b to, for example, 200 ° C., the content rate of oxygen radical molecules is increased, and thereby the wiring pattern portion is not caused without overheating of the peripheral portion. Therefore, the nano metal particles can be sintered by spraying plasma gas in a short time of about 30 seconds, for example.

The operating conditions of each atmospheric plasma generator 1 6, 20 are, for example, the rise time of the voltage applied from the power supply 2 6, 40 to the pair of electrodes 2 4, 2 4, 3 8, 3 8 or At least one of the falling times is 100 seconds or less, the repetition frequency of the waveform of the voltage V from the power supply devices 26 and 40 is 0.5 to 100 kHz, and the pair of electrodes 2 4 , 2, 3 8, and 38 can be appropriately selected within the range of 0.5 to 200 kV / cm 2. Further, it is desirable to adjust the distance between the plasma nozzles 2 2 b and 30 b of each of the nozzles 22 and 36 and the insulating substrate 12 within a range of 1 to 20 mm, for example.

The table in FIG. 5 shows that a wiring path is formed by jetting oxygen radical molecules from the atmospheric plasma generator 20 to the wiring pattern portion made of the paste material. In the example shown in FIG. 5, a line with a pad is drawn on the raw glass as a wiring pattern portion made of the paste material. The thickness of the paste material was approximately 4 O nm, and the line length between pads was set to approximately 3 mm. Each line width was set to 10 m, 2 0 πι, and 30 μππι, respectively. After forming the wiring by injecting oxygen radical molecules from the atmospheric plasma generator 20 to each wiring pattern portion for about 10 seconds, the line resistance between each pad was measured for each line. As shown in Fig. 5, the resistance value was measured in the wiring path of any line width, and it was confirmed that the conductive path was formed. In addition, the sintering of the metal material in the paste material can be achieved by an extremely short plasma irradiation operation of about 10 seconds. It was.

As each of the plasma generators described above, a vacuum plasma generator can be used. However, by using the atmospheric plasma generator as described above, the insulating substrate 12 to be processed can be processed in the air without being placed in the vacuum chamber. It is desirable to use an atmospheric plasma generator.

In the above description, the example in which the present invention is applied to the formation of a wiring path has been described. However, the present invention can be applied to repair of a broken portion of a wiring path. In this case, a paste material containing nano metal particles and an organic binder is supplied to the wiring defect portion to be repaired on the circuit board, and the supplied paste material is exposed to oxygen radical molecules or its gas.

In addition, instead of spraying oxygen radical molecules on a pattern portion formed of a paste material containing nano metal particles and a binder made of an organic material, by spraying active oxygen (zone) or a gas containing this, The organic binder in the paste material can be removed, so that the nano metal particles in the paste material can be brought into contact with each other and sintered. Industrial applicability

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. '

Claims

The scope of the claims

1. A pattern part for wiring is formed on an insulating substrate with a paste material containing nano metal particles and an organic binder, and the pattern part formed with the paste material is replaced with an oxygen radical molecule or a gas thereof. A method of forming electrical wiring, including exposure to heat.

2. The forming method according to claim 1, wherein oxygen radical molecules are sprayed toward the pattern portion.

3. The method of claim 1, wherein the oxygen radical molecules are formed using a plasma generator.

4. The method of claim 3, wherein the plasma generator is an atmospheric plasma generator.

5. The method according to claim 1, wherein the nano metal particles have a particle diameter of several nanometers to several hundred nanometers.

6. The method according to claim 5, wherein the nano metal particles are covered with a protective film made of an organic material.

7. The method according to claim 5, wherein the pattern portion is formed on the insulating substrate by spraying the paste material by an ink jet method.

8. Supplying paste material containing nano metal particles and organic binder to the wiring defect portion to be repaired on the circuit board, and exposing the supplied paste material to oxygen radical molecules or its gas Electrical wiring repair method.