JP2005209907A - Annealing method and base member with wiring formed using annealing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an annealing method capable of reducing the electric resistance of a metal thin film by selectively and effectively annealing only the metal thin film in a short time. <P>SOLUTION: A thin film 2 containing a conductive material is formed on a base member 1, and electric power is supplied to the thin film 2 by electrically connecting a first electrode 3 and a second electrode 4 both having electric potentials therebetween. Consequently, a part supplied with the electric power is heated, so that the electric resistance of the part is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an annealing method for reducing the electrical resistance value of a thin film comprising a conductive material formed on a substrate, and a substrate on which an electrode is formed using the annealing method.

  Conventionally, the use of a metal thin film formed on a silicon substrate or glass substrate by sputtering or CVD as wiring has been applied to devices such as semiconductors and displays. When a metal thin film is used for wiring, it is preferable that the electrical resistance value is low. A metal thin film formed by sputtering or CVD has a problem that its electric resistance value is several times higher than the bulk value of the material, and a method for reducing the electric resistance value is desired. In recent years, a method of forming a metal thin film using an ink in which metal particles are dispersed in a solvent by an ink-jet method, a dispenser method, or various printing methods has been implemented. In this case, since the electric resistance value is considerably higher than the bulk value of the material, a method for reducing the electric resistance value is essential.

  As a method for reducing the electrical resistance value, a long-time annealing method in which the entire substrate is heated and held for a long time is well known. In this annealing method, it is necessary to keep the entire base material at a high temperature. This causes bending of the base material, and if annealing is performed at a temperature with little damage to the base material, sufficient electrical resistance can be obtained. There is a problem that the value cannot be reduced.

In order to solve this problem, a proposal as in Patent Document 1 has been made. In this method, the metal thin film formed on the substrate is irradiated with excimer laser light, the metal thin film is heated and melted, and then cooled and recrystallized to reduce the electric resistance value. In this case, since the temperature of the entire substrate is not raised by the laser beam, but only the metal thin film portion can be selectively heated, the electrical resistance value of the metal thin film with little damage to the substrate. Can be reduced.
JP-A-5-21387

  However, in the conventional configuration, in order to selectively irradiate the metal thin film with the laser beam, it is necessary to focus the laser beam to a certain size, and the focused laser beam is applied to all the metal thin films formed on the substrate. Irradiation with light takes much time and is not efficient. In addition, when trying to selectively irradiate a metal thin film with laser light, even if the laser light is considerably condensed and alignment is performed strictly, a portion where the laser light is directly irradiated to the base material is generated. However, damage will occur in that part.

  In recent years, many studies have been conducted on using a resin film as a substrate from the viewpoint of flexibility and low cost. However, when a resin film is used, damage caused by a laser becomes larger.

  An object of the present invention is to solve the above-mentioned problems, and selectively anneal only a portion of a metal thin film efficiently in a short time, whereby an annealing method capable of reducing the electric resistance value of the metal thin film, Another object of the present invention is to provide a substrate on which wiring is formed using the annealing method.

  In order to solve the above-described conventional problems, the annealing method of the present invention includes a step of forming a thin film containing a conductive material on a base material and electrically connecting at least two electrodes having a potential difference to the thin film. And a step of reducing the electrical resistance value of the energized portion by generating electricity.

  By this method, it is possible to selectively generate heat only in the thin film portion, which makes it possible to reduce the electrical resistance value of the thin film portion with little damage to the substrate. In addition, when the part where the electrical resistance value is low and the part where the electrical resistance value is not low are mixed after the start of energization, the part where the electrical resistance value is low is difficult to generate heat and the electrical resistance value is not sufficiently low. Since the portion easily generates heat, the overall electric resistance value can be stably reduced finally.

  In the annealing method, the current is limited for energization of at least two electrodes having a potential difference.

  In this method, since the current is limited when energization is performed and the electric resistance value of the thin film is reduced, the amount of heat generation is also reduced at the same time, and the problem of excessive heat generation is eliminated. Further, even if there is a state where the resistance value is partially insufficiently reduced, only that part does not generate abnormal heat, so that the electrical resistance value can be stably reduced.

  In the annealing method, the thin film containing the conductive material is electrically separated into a plurality of thin films, and the first electrode of the two electrodes includes at least two or more. The second electrode is electrically connected simultaneously with the thin film, and the second electrode is electrically connected to any one of the thin films electrically connected by the first electrode.

  When a plurality of electrically separated thin films are energized simultaneously with the same electrode, after the start of energization, it becomes easier for electricity to flow to the thin film on the side where the electrical resistance value has decreased, and the other thin film has electricity. It becomes difficult to flow, thereby preventing heat generation, and as a result, the electric resistance value is not sufficiently reduced.

  In this method, since a plurality of electrically separated thin films are not energized simultaneously by the same electrode, the electric resistance value of each thin film can be stably reduced. In addition, since the first electrode of the two electrodes is connected simultaneously with two or more thin films, it is possible to easily connect the two electrodes to each thin film.

  Moreover, in the said annealing method, the thin film was formed by apply | coating to the base material the liquid which disperse | distributed the electroconductive material with an average particle diameter of 2-100 nm.

  In this method, a particulate conductive material is dispersed in a liquid, and the electric resistance value of the thin film formed on the substrate is much higher than the bulk value of the conductive material. is there. In this case, it is very important to reduce the electrical resistance value uniformly and stably, and after the start of energization, there is an annealing method that can selectively generate heat in a portion where the electrical resistance value has not been sufficiently reduced. Can be preferably used.

  Further, in the annealing method, the step of once raising the temperature of the base material on which the thin film containing the conductive material is formed below the heat resistance temperature of the base material is added before the step of energizing the thin film. .

  When the resistance value of the thin film before energization is very high, for example, in the case of a thin film formed by depositing a particulate conductive material in a solvent, it is difficult to energize and generate heat. In this method, the temperature of the substrate is raised once to a temperature within a range where damage to the substrate does not occur, and the electric resistance value is insufficiently reduced, but the electric resistance value is reduced to a range where heat can be generated by energization. Since the process is included, even when the resistance value of the thin film before energization is very high, the electrical resistance value can be sufficiently reduced.

  The substrate is a resin film.

  In this method, since the thin film itself generates heat, unlike the case of using a laser, there is little damage to other than the thin film, and therefore it can be suitably used even if the substrate is a resin film.

  In the base material of the present invention, wiring is formed using the annealing method.

  In this configuration, a substrate on which wiring having a reduced electric resistance value is formed by using an annealing method in which only a thin film portion generates heat, and a substrate with little damage can be obtained.

  According to the present invention, it is possible to selectively generate heat only in the thin film portion, and thereby it is possible to reduce the electric resistance value of the thin film portion with little damage to the base material. In addition, when the part where the electrical resistance value is low and the part where the electrical resistance value is not low are mixed after the start of energization, the part where the electrical resistance value is low is difficult to generate heat and the electrical resistance value is not sufficiently low. Since the portion easily generates heat, the overall electric resistance value can be stably reduced finally.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a schematic configuration diagram showing an annealing method according to an embodiment. 1 is a base material made of a resin film, and uses a ZEONOR film (manufactured by Nippon Zeon Co., Ltd.) from the viewpoint of heat resistance and transparency. The substrate 1 has a glass transition temperature of 163 ° C. and a film thickness of 100 μm. Reference numeral 2 denotes a conductive thin film formed on the substrate 1. In this embodiment, the conductive thin film 2 is formed by applying a liquid in which metal particles are dispersed in a solvent to the substrate 1 by an ink jet method. As the metal particles, gold, silver, copper, platinum or the like is preferably used. Moreover, what is called a nanoparticle whose average particle diameter of a metal particle is 1-100 nm is used preferably. In the present embodiment, silver particles having an average particle diameter of 20 nm are used, and the amount used is 30% by weight. The thin film 2 has a plurality of (11 in FIG. 1) line shapes, and the length of the dried line is 100 mm, the line width is 200 μm, and the film thickness is 0.5 μm. Reference numeral 3 denotes a first electrode made of metal, which is electrically connected to a plurality of thin films. Reference numeral 4 denotes a second electrode made of metal, which is electrically connected to one thin film, supported by a means not shown so as to be movable in the direction of the arrow, and sequentially connected to another thin film. It is configured as follows. Reference numeral 5 denotes a power source, which is configured to be able to energize the first electrode 3 and the second electrode 4 through the connection line 6. In addition, the power source 5 includes a limiting unit that limits the amount of current that flows to the first electrode 3 and the second electrode 4.

  Next, the operation will be described. The electrical resistance value between the first electrode 3 and the second electrode 4 of the thin film formed on the substrate 1 was 100 kΩ. The volume resistance value at this time is 0.01 Ω · cm. Since the volume resistance value of the bulk of silver is 1.6 μΩ · cm, the volume resistance value of the thin film 2 is as high as 6250 times. In contrast, first, the entire substrate 1 is left in an environment of 140 ° C. for 30 minutes. If it is 140 degreeC, the base material 1 will not have a heat damage. When the resistance value between the electrodes was measured after this treatment, it was possible to reduce the value from 100 kΩ to 10 kΩ. Next, the power source 5 was set to a voltage of 100 V, a limiting current of 0.02 amperes, and the thin film 2 was energized. Since the second electrode is connected only for each thin film, energization is performed for each thin film. The state change of the thin film 2 when the thin film 2 is energized is shown in FIG. In order to make it easy to understand, the aspect ratio of the base material 1 and the thin film 2 is considerably changed and illustrated. FIG. 2A shows a state before energization, in which silver particles are stacked as particles. Next, (b) shows a state after a certain period of time from the start of energization. The silver particles are partially bonded due to heat generated by energization, and the bonding varies in the longitudinal direction of the thin film. Particularly in the part A, the bonding of silver particles is considerably advanced with respect to other parts. At this time, the electrical resistance value of the A portion is lower than that of the other portions. In this state, the amount of heat generated in part A is smaller than in other parts. Therefore, if energization is continued in this state, heat is generated at portions other than the portion A, and the coupling of the portions where the heat is generated proceeds more and more. Finally, as shown in (c), the entire coupling proceeds and the resistance value can be reduced. In other words, where the coupling is advanced, the electrical resistance value is reduced and heat generation is suppressed, and where the coupling is not advanced, the electrical resistance value is not relatively low, and that portion is then actively heated. A self-control operation is performed. Further, since the power source 5 is current limited, the amount of heat generated between the electrodes of the thin film 2 gradually decreases, and only a portion where the electrical resistance value is not sufficiently lowered continues moderate heat generation. It will be. At this time, when there is no current limitation and constant voltage control is performed, the total amount of heat generation increases as the electrical resistance value decreases, and the desired controlled heat generation becomes impossible.

  Finally, the resistance value could be reduced to 80Ω between the electrodes. The volume resistance value at this time is 8 μΩ · cm, which can be reduced to a considerably low value of 5 times the bulk value. At this time, the damage to the base material 1 is within 2 μm in the horizontal direction and 6 μm in the vertical direction of the portion where the thin film is formed, and can be suppressed to a level at which there is no problem in normal use. .

  Then, by moving the second electrode 4 in the direction of the arrow and repeatedly energizing the other thin film 2, all the electric resistance values of the thin film 2 of the substrate 1 can be reduced.

  According to this method, the thin film 2 is energized by the first electrode 3 and the second electrode 4 to generate heat only in the energized portion and reduce the electric resistance value of the energized portion. Only the portion can be selectively heated, and thus the electric resistance value of the thin film 2 can be reduced with little damage to the substrate 1. In addition, when the part where the electrical resistance value is low and the part where the electrical resistance value is not low are mixed after the start of energization, the part where the electrical resistance value is low is difficult to generate heat and the electrical resistance value is not sufficiently low. Since the portion easily generates heat, the overall electric resistance value can be stably reduced finally.

  In addition, according to such a method, since the current is limited to the power source, when energization is performed and the electric resistance value of the thin film is reduced, the amount of generated heat is also reduced at the same time, and the problem is that the heat is excessively generated. Disappears. Further, even if there is a state where the resistance value is partially insufficiently reduced, only that part does not generate abnormal heat, so that the electrical resistance value can be stably reduced.

  The first electrode 3 is electrically connected simultaneously with the plurality of thin films 2, and the second electrode 4 is any one of the thin films 2 electrically connected by the first electrode 3. 2 is electrically connected. When a plurality of electrically separated thin films 2 are simultaneously energized by the same electrode, electricity is likely to flow to the thin film 2 on the side where the electrical resistance value has decreased after starting energization, while other thin films 2 are electrically Becomes difficult to flow. As a result, the other thin film 2 does not generate heat, and as a result, the electrical resistance value is not sufficiently reduced. According to this method, since the plurality of electrically separated thin films 2 are not simultaneously energized by the same electrode, the electric resistance value of each thin film 2 can be stably reduced. In addition, since the first electrode 3 of the two electrodes is simultaneously connected to two or more thin films 2, it is possible to easily connect the two electrodes to each thin film 2.

  Further, according to this method, the thin film 2 is formed by applying a liquid in which a conductive material having an average particle diameter of 2 to 100 nm is dispersed to the base material 1, and is formed on the base material 1. Only the electric resistance value of the thin film 2 is considerably higher than the bulk value of the conductive material. In this case, it is very important to reduce the electric resistance value uniformly and stably, and this method that can selectively generate heat in a portion where the electric resistance value has not been sufficiently reduced after the start of energization is very Can be preferably used.

  Further, when the electric resistance value of the thin film 2 before energization is very high, for example, in the case of the thin film 2 formed by forming a film in which a particulate conductive material is dispersed in a solvent, energization is performed to generate heat. Is difficult. According to such a method, the temperature of the base material 1 is once raised to a temperature in a range where damage to the base material 1 does not occur, and this is insufficient for reducing the electric resistance value. Since the process of reducing the resistance value is included, even when the electrical resistance value of the thin film 2 before energization is very high, the electrical resistance value can be sufficiently reduced.

  Further, according to this method, the base material 1 uses a resin film, and unlike the case where a laser is used to generate heat in the thin film 2 itself, damage to other than the thin film 2 is very small. Even a resin film can be suitably used.

  In addition, according to such a configuration, the wiring 1 with reduced electric resistance value is formed by using the annealing method that generates heat only in the thin film 2 portion, so that the substrate 1 with less damage can be obtained.

  Moreover, in this Embodiment, although the base material 1 used the resin film, this can also use base materials, such as glass and a silicon | silicone, suitably.

  Moreover, in this Embodiment, although the thin film 2 was formed by the inkjet method, this may be formed by various printing methods, the dispenser method, etc. Furthermore, although the liquid which disperse | distributed the metal particle was used for formation of the thin film 2, what formed the thin film 2 by sputtering and CVD may be used for this.

  Further, in the present embodiment, both the first electrode 3 and the second electrode 4 are made of metal, which is provided with conductive rubber at the contact portion with the thin film 2 and in contact with the thin film 2. It can also be suitably used to keep the film in good condition.

  In the present embodiment, a long-time annealing process is performed. Needless to say, this process is not necessarily required if the resistance value between the electrodes after the formation of the thin film 2 is, for example, 10 kΩ or less.

  In the present embodiment, the way of energizing the thin film 2 is not particularly limited, but this can be preferably performed not only by applying DC but also by applying intermittent pulses.

  The annealing method according to the present invention has the effect of heating the thin film by energizing the thin film containing the conductive material formed on the base material, and only reduces the resistance value of the thin film. In addition, it is useful for enhancing the surface properties of the thin film, increasing the adhesive force with the base material, and heating the material in the vicinity thereof by the heat generation.

Schematic configuration diagram of an annealing method in an embodiment of the present invention Sectional drawing which shows the state in which an electrical resistance value reduces with the annealing method in embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Thin film 3 1st electrode 4 2nd electrode 5 Power supply 6 Connection line

Claims (7)

Forming a thin film comprising a conductive material on a substrate;
Energizing the thin film by electrically connecting at least two electrodes having a potential difference, generating heat in the energized part and reducing the electrical resistance value of the energized part;
An annealing method comprising: 2. An annealing method according to claim 1, wherein the current is limited in energization to at least two electrodes having a potential difference. The thin film including the conductive material is electrically separated into a plurality of thin films, and the first electrode of the two electrodes is electrically simultaneously with at least two or more of the thin films. The connected second electrode is electrically connected to any one of the thin films among the thin films electrically connected by the first electrode. The annealing method described. The annealing method according to any one of claims 1 to 3, wherein the thin film is formed by applying a liquid in which a conductive material having an average particle diameter of 2 to 100 nm is dispersed to a substrate. The step of raising the temperature of a base material on which a thin film comprising a conductive material is formed below the heat resistance temperature of the base material is added before the step of energizing the thin film. 5. The annealing method according to any one of 4 above. The annealing method according to claim 1, wherein the substrate is a resin film. The base material with which wiring was formed using the annealing method in any one of Claims 1-6.

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