JP3652398B2 - Pattern forming method for conductive metal thick film - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for forming a thick conductive metal film having a desired pattern, and more particularly to a method for forming electrodes and wiring patterns directly on a substrate without masking or etching. It is.
[0002]
[Prior art]
As a method for forming a conductive metal electrode or wiring pattern made of platinum, gold, silver, copper, aluminum or the like on a substrate, a thick film paste method, a sputtering method, a vacuum deposition method, a plating method, or the like is known. In these methods, in order to form a thick conductive metal film having a desired pattern, a thick metal film is formed by masking unnecessary portions on the substrate, or on the entire surface of the substrate. After the thick metal film is formed, a resist film is formed at a necessary portion, and an unnecessary thick metal film where the resist film is not formed is etched and removed.
[0003]
[Problems to be solved by the invention]
In such a conventional conductive metal thick film pattern forming method, when unnecessary portions on the substrate are shielded by masking, the thick film paste method forms a thick film of several μm or more in one process. Although it can be obtained, a baking step is required after coating, and the sputtering method and the vacuum evaporation method have a problem that it takes a very long time to obtain a thick film of several μm or more because the film forming speed is low. In addition, when forming a thick metal film on the entire surface and then removing the unnecessary thick metal film by etching, it is necessary to form a resist or perform etching. There is a problem that the number of processes is increased.
[0004]
Furthermore, since platinum, gold, silver, etc. are expensive, copper or aluminum is generally used. However, these metals are easily oxidized, and particularly in the case of aluminum, they are very easily oxidized. In the paste method or plating method, oxidation may occur in the obtained film, and the electrical resistivity may deteriorate over time.
[0005]
The present invention has been made in view of the above-mentioned problems, and patterning is performed on a conductive metal thick film having a small change in electrical resistivity over time directly on a substrate without requiring masking, etching, and other processing steps before and after film formation. It aims to provide a method.
[0006]
[Means for Solving the Problems]
The above object is to generate conductive metal ultrafine particles by heating and evaporating a conductive metal material by high-frequency induction heating in an inert gas atmosphere ultrafine particle generation chamber having a purity of 99.9999% or more. It is entrained in an inert gas and transferred into a film forming chamber in a vacuum atmosphere by a transfer tube, and is disposed in the film forming chamber in advance from a nozzle attached to the tip of the transfer tube and heated to a temperature below the melting point of the ultrafine particles. The ultrafine particles are sprayed with the pressure of the inert gas toward the substrate whose temperature has been increased, and one of the nozzle or the substrate is moved at an arbitrary moving speed, and a desired film thickness is formed on the substrate. This is achieved by a conductive metal thick film pattern forming method, characterized by forming a conductive metal thick film having a pattern.
[0007]
[Action]
According to the method of the present invention, ultrafine particles of conductive metal are generated in an inert gas atmosphere having a purity of 99.9999% or more, and the generated ultrafine particles are transported by the inert gas, and the melting point of the ultrafine particles. to form a thick film conductive metal on the substrate I by the injecting toward the advance temperature elevated substrate moving at below the nozzle which is heated to a temperature disposed in a vacuum atmosphere any movement speed Therefore , it is possible to form a conductive metal thick film having a desired pattern with a desired film thickness in one step, and to obtain a conductive metal thick film having a low resistance and a small change in electrical resistivity over time. .
[0008]
【Example】
Hereinafter, a method for forming a conductive metal thick film pattern according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0009]
FIG. 1 is a schematic view showing an example of an apparatus used for carrying out the present invention, which is a metal partial film forming apparatus previously filed by the present applicant as Japanese Patent Application No. 6-196051. The apparatus generally includes an ultrafine particle generation chamber 1, a film formation chamber 2, a transfer pipe 3 connecting them, and helium (He) gas flowing from the ultrafine particle generation chamber 1 to the film formation chamber 2. Vacuum pumps 15 and 16 and a helium gas purification and recycling system 17 for returning to the bottom of the gas.
[0010]
In the ultrafine particle generation chamber 1, a crucible 6 (an inner diameter of 5 mmφ, an outer diameter of 15 mmφ, and a height of 10 mm) is disposed as an evaporation source, and a conductive metal material 22, for example, aluminum (Al) is accommodated. A coil 7 c for induction heating is wound around the crucible 6, and both ends thereof are connected to a high frequency power source 7 (150 kHz) provided outside the ultrafine particle generation chamber 1. The reason why the high frequency induction heating method is adopted here is as follows. That is, in the resistance heating method, the crucible itself is heated by Joule heat using a heating element, and the internal evaporation material is heated by heat transfer from the crucible. Even if the melted evaporative material convects, the viscosity is high and insufficient, the heating becomes uneven, and the particle size distribution of the ultrafine particles produced due to bumping is widened. On the other hand, the high frequency induction heating method heats the crucible and the evaporating material by generating eddy currents, so that the particle size distribution of the ultrafine particles generated with uniform heating is narrow and sharp.
[0011]
Directly above the crucible 6, a lower end of a vertically arranged transport pipe 3 (outer diameter ¼ inch) is disposed, and a large-diameter suction pipe sharing an axis with the transport pipe 3 is disposed above the lower end portion. 5 is provided. The annular space between the suction pipe 5 and the transport pipe 3 is connected to the suction side of the vacuum pump 16 via the valve 13. The suction pipe 5 is provided to suck in ultrafine particles staying in the ultrafine particle generation chamber 1 other than the portion directly above the crucible 6. A shutter system 9 is provided to support the bottom of the crucible 6. The shutter system 9 is referred to FIG. 2, and as shown in FIG. 2A, the crucible 6 is moved about 30 mm in the direction indicated by the arrow a from the position where the crucible 6 is directly below the transport pipe 3 in FIG. As shown in B, the crucible 6 is positioned either at a position where the crucible 6 is directly below the annular space between the suction pipe 5 and the transport pipe 3. That is, the metal vapor from the crucible 6 is cooled to the carrier gas (He) in the atmosphere, and the rising 20 as ultrafine particles is sucked into the carrier tube 3 at the position A in FIG. 2, and the position B in FIG. Then, it is sucked into the suction pipe 5. The movement of the crucible 6 between the two positions is performed according to a program by a controller (not shown), and the transfer of ultrafine particles is interrupted. Furthermore, a vacuum gauge 1G is attached to the ultrafine particle generation chamber 1.
[0012]
In the film forming chamber 2, an upper end portion of the transfer pipe 3 and a nozzle 4 having an inner diameter of 0.4 mmφ attached to the tip end are inserted, and a nozzle heater 23 connected to an external AC power supply 24 is wound around the nozzle 4. Has been. A substrate 8 held by the substrate holder 10 is disposed in the vicinity of the top of the nozzle 4 (variable within a range of 0.1 to 2.0 mm). The substrate holder 10 is program-controlled by a controller (not shown), and the substrate 8 is scanned at a speed of 0.01 to 2 mm / second in the in-plane X-axis direction and the Y-axis direction perpendicular thereto. Since the transport pipe 3 has a length, it takes a time of 0.1 second until the outlet of the nozzle 4 is reached after the ultrafine particles are sucked. Therefore, when the scanning of the substrate 8 stops at a certain point, stops the film formation, and moves to the next point, the movement to the next point is made after the time until the ultrafine particles are exhausted from the transport pipe 3 has elapsed. It is programmed to start. That is, the metal film to be formed does not pierce the tail. When reaching the next point and restarting the film formation, the movement for forming the film starts after the time until the ultrafine particles begin to be ejected from the tip of the nozzle 4. In addition, a heater unit for heating the substrate 8 is built in the substrate holder 10, and the substrate 8 is mounted by a temperature controller (not shown) to which a temperature signal from a thermocouple 11 attached to the substrate 8 is input. It is maintained at a predetermined temperature. The film forming chamber 2 is connected to the suction side of a vacuum pump 15 via a valve 14 and is attached with a vacuum gauge 2G.
[0013]
The piping on the exhaust side of the vacuum pump 15 and the vacuum pump 16 is combined into one, connected to the helium gas purification / recycling system 17 via the valve 19, and further connected to the bottom of the ultrafine particle generation chamber 1 for conveyance. Helium gas is sent as gas. A helium gas cylinder 18 having a purity of 99.9999% or more is connected to the bottom of the ultrafine particle generation chamber 1 through a valve 12. A branch pipe provided with a valve 20 is attached in the vicinity of the valve 19 between the vacuum pumps 15 and 16 and the valve 19.
[0014]
A method for forming a conductive metal thick film pattern on a glass substrate using the above-described metal partial film forming apparatus will be exemplified below.
[0015]
(Example 1) Referring to FIG. 1, the ultrafine particle production chamber 1 and the film formation chamber 2 are first evacuated. That is, the valves 13, 14, and 20 are opened, the valves 12 and 19 are closed, and the vacuum pumps 15 and 16 are evacuated to a pressure of 10 ⁻⁴ Pa. Next, while the operation of the vacuum pumps 15 and 16 is continued, the valve 20 is closed, the valves 12 and 19 are opened, and a predetermined amount of helium gas having a purity of 99.9999% or more is introduced into the ultrafine particle generation chamber 1 from the helium gas cylinder 18. The pressure of the ultrafine particle generation chamber 1 is maintained at 2 kg / cm ² by adjusting the opening of the valve 13. The introduced helium gas flows through the suction pipe 5 at 30 SLM (standard state liters per minute), and flows through the transfer pipe 3 into the film forming chamber 2 at 10 SLM. The helium gas that has entered the film forming chamber 2 is exhausted from the valve 14 so that the pressure in the film forming chamber 2 is maintained at about 1 Torr, and there is a difference of about 2 kg / cm ² between the ultrafine particle generating chamber 1 and the film forming chamber 2. Pressure is generated. At this time, the valve 12 is closed.
[0016]
The reason why the flow rate to the suction pipe 5 is increased is that if there are ultrafine particles staying in the ultrafine particle production chamber 1 without being sucked into the transport pipe 3, these become aggregates during the stay, and at some time the transport pipe 3 This is to adversely affect the film that is being transported and being formed on the glass substrate 8 in the film forming chamber 2, thereby preventing the formation of aggregates.
[0017]
When 30 minutes or more have passed in this state , the gas discharged from the helium gas purification and recycling system 17 becomes helium having a purity of 99.9999% or more, and the atmosphere of the entire system becomes helium gas having a purity of 99.9999% or more. That is, helium gas having a purity of 99.9999% or higher is circulated in the direction indicated by the arrow.
[0018]
After the above condition is prepared, aluminum (purity 99.9995% or more) as the conductive metal material 22 previously placed in the crucible 6 is induction-heated to 1430 ° C. by the high-frequency power source 7 and evaporated to produce ultrafine particles. Let Most of the generated ultrafine particles of aluminum are sucked into the transfer tube 3 together with helium gas, and in the film forming chamber 2, the nozzle 4 heated to 600 ° C. by the nozzle heater 23 to the heater unit of the substrate holder 10 in advance is heated to 250 ° C. A thick aluminum film is formed by spraying on the glass substrate 8 heated to a temperature.
[0019]
At this time, since the glass substrate 8 can be scanned in the X-axis direction and the Y-axis direction in the plane, any combination on the glass substrate 8 can be performed by combining the operation of the shutter system 9 to intermittently convey the aluminum ultrafine particles. It is possible to form an aluminum thick film having an arbitrary pattern extending from this location to any location.
[0020]
The specific resistance of the aluminum thick film thus formed having a thickness of 20 μm, a width of 0.4 mm, and a length of 50 mm is 3.51 × 10 ⁻⁶ Ωcm (20 ° C.), which is about 1.3 times that of bulk aluminum. It was twice. Further, as a result of the accelerated life test of the moisture resistance with respect to the electrical resistivity under the conditions of 50 ° C. and 95% RH performed on the thick aluminum film after the film formation, as shown in FIG. 3, 1000 hours or more (40 days or more) Even after elapse, the specific resistance did not change at all, indicating that the moisture resistance was extremely excellent.
[0021]
(Comparative Example 1) A thickness of 20 μm, a width of 0.4 mm, and a length are the same as in Example 1 except that the purity of the helium gas is reduced to 99.99% and the heating temperature of the nozzle 4 is set to 100 ° C. A 50 mm thick aluminum film was formed on the glass substrate 8, and the specific resistance was 500 to 900 times that of bulk aluminum.
[0022]
(Comparative Example 2) Except for reducing the purity of the helium gas to 99.99%, an aluminum thick film having a thickness of 20 μm, a width of 0.4 mm, and a length of 50 mm was formed in the same manner as in Example 1, except that the glass substrate 8 The specific resistance was 200 to 700 times that of bulk aluminum.
[0023]
(Comparative Example 3) A thick aluminum film having a thickness of 20 μm, a width of 0.4 mm, and a length of 50 mm on the glass substrate 8 in exactly the same manner as in Example 1 except that 99.9% helium gas having a lower purity was used. Formed. The specific resistance of the thick film exceeded the measurement limit of 9.6 Ωcm, and could not be measured.
[0024]
(Example 2) In the metal partial film forming apparatus (FIG. 1) used in Example 1, 98.5 parts by weight of aluminum and 1.5 parts by weight of copper (Cu) were put in the crucible 6 and the others. In the same manner as in Example 1, a thick film of aluminum-copper (Al-Cu) alloy (thickness 20 μm, width 0.4 mm, length 50 mm) was patterned on the glass substrate 8.
[0025]
This alloy thick film contained 1% by weight of copper and exhibited a specific resistance of 3.5 × 10 ⁻⁶ Ωcm (20 ° C.). Further, when this alloy thick film was heated in a vacuum furnace at a temperature of 350 ° C. for 30 minutes and the specific resistance was measured again, it was 3.5 × 10 ⁻⁶ Ωcm (20 ° C.) and no change was observed.
[0026]
Further, when a moisture resistance accelerated life test on the electrical resistivity of the thick alloy film was performed under the same conditions as in Example 1, the specific resistance hardly changed even after 1000 hours or more.
[0027]
(Example 3) In the metal partial film forming apparatus used in Example 1 (Fig. 1), tin (Sn) was put in the crucible 6 and induction heated to 1050 ° C, and the heating temperature of the nozzle 4 was set to 200 ° C. A thick tin film (thickness 20 μm, width 0.4 mm, length 50 mm) was formed on the glass substrate in the same manner as in Example 1 except that the heating temperature of the substrate was 200 ° C.
[0028]
The specific resistance of the tin thick film was 1.49 × 10 ⁻⁵ Ωcm (23 ° C.), which was about 1.2 times the bulk value. Also, there was almost no change in electrical resistivity with time.
[0029]
As mentioned above, although each Example of this invention was described, of course, this invention is not limited to these, A various deformation | transformation is possible based on the technical idea of this invention.
[0030]
For example, in each of the examples, helium was used as an inert gas having a purity of 99.9999% or higher, but the same effect can be obtained by using argon or neon other than helium.
[0031]
In each embodiment, the glass substrate 8 is adopted, but the substrate is not limited to glass, and various types can be used.
[0032]
Moreover, in Example 2, although the alloy of aluminum and copper was demonstrated as an electroconductive metal material, aluminum alloys other than this, for example, aluminum-silicon (Al-Si), aluminum-silicon-copper (Al-Si-), were described. Cu), aluminum-silicon-titanium (Al-Si-Ti), and aluminum-copper-titanium (Al-Cu-Ti) alloys that have excellent moisture resistance and a small electrical resistivity change over time Pattern formation is possible.
[0033]
Furthermore, in Examples 1 and 2, the temperature of the nozzle 4 is heated to 600 ° C. which is lower than the melting point of the aluminum or aluminum alloy with respect to the ultrafine particles of aluminum or aluminum alloy, and the substrate 8 is heated to 250 ° C. in advance . In Example 3, the nozzle 4 was heated to 200 ° C., which is equal to or lower than the melting point of tin, with respect to the ultrafine particles of tin, and the substrate 8 was heated to 200 ° C. in advance, but was heated by the nozzle 4 . range nozzle 4 is not closed by the ultrafine particles, the heating of the nozzle 4 definitive ranges ultrafine particles do not form aggregates and preheating of the substrate 8, is rather preferable than providing a homogeneous thick metal film or a desired film thickness, Thus, it is possible to form a thick conductive metal film having a desired pattern in one step, and to obtain a thick conductive metal film with low resistance and small change in electrical resistivity over time .
[0034]
In each of the above embodiments, the shutter system 9 is used and the helium gas as the carrier gas is circulated. However, the shutter system 9 is not always necessary, and the conductive metal is not required to circulate the carrier gas. Thick film pattern formation is possible.
[0035]
【The invention's effect】
As described above, according to the pattern forming method of the conductive metal thick film of the present invention, it is not necessary to perform a process such as masking or etching, and an arbitrary film thickness can be applied to an arbitrary position on the preheated substrate. Since the conductive metal thick film having a pattern can be formed in one step, the formation cost of the patterned conductive metal thick film can be greatly reduced. In addition, since an inert gas with a purity of 99.9999% or more is used, even a thick film of a metal that is easily oxidized such as aluminum or an aluminum alloy has low resistance and stable film characteristics over a long period of time. Things are obtained. Therefore, an electrical component using a thick film circuit made of an easily oxidized metal such as aluminum or aluminum alloy formed by the method of the present invention has high reliability. In addition, according to the conductive metal thick film pattern forming method of the present invention, not only can a conductive circuit be formed on a substrate, but also electrical circuit repair, electrode formation, lead wire bonding, and the like are possible. .
[Brief description of the drawings]
FIG. 1 is a schematic view of a metal partial film forming apparatus used in an embodiment of a conductive metal thick film pattern forming method of the present invention.
FIGS. 2A and 2B are diagrams illustrating an operation of the shutter system in the apparatus, in which A is a transport state of ultrafine particles, and B is a transport stop state.
FIG. 3 is a graph showing the results of a moisture resistance accelerated life test regarding the electrical resistivity of the aluminum thick film formed according to the first embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ultrafine particle production | generation chamber 2 Film formation chamber 3 Transport pipe 4 Nozzle 5 Suction pipe 6 Crucible 7 High frequency power supply 8 Substrate 9 Shutter system 15 Vacuum pump 16 Vacuum pump 17 He gas purification recycling system 22 Conductive metal material

Claims (5)

Conductive metal material is heated and evaporated by high-frequency induction heating in an ultrafine particle generation chamber of an inert gas atmosphere with a purity of 99.9999% or more to generate conductive metal ultrafine particles, and the ultrafine particles are accompanied by the inert gas. The substrate is placed in the film forming chamber from the nozzle attached to the tip of the transport tube and heated to a temperature not higher than the melting point of the ultrafine particles, and is heated in advance by the transfer tube. Injecting the ultrafine particles toward the substrate with the pressure of the inert gas and moving either the nozzle or the substrate at an arbitrary moving speed has a desired pattern with a desired film thickness on the substrate. A method for forming a conductive metal thick film pattern, comprising forming a thick film of conductive metal.   The method for forming a conductive metal thick film pattern according to claim 1, wherein the conductive metal material is aluminum, an aluminum alloy, or tin.   3. The pattern forming method for a conductive metal thick film according to claim 2, wherein the aluminum alloy is Al-Si, Al-Cu, Al-Si-Cu, Al-Si-Ti, or Al-Cu-Ti.   The pattern forming method for a conductive metal thick film according to claim 1, wherein the inert gas is helium, argon, or neon. The inert gas transports ultrafine particles of the conductive metal produced in the ultrafine particle production chamber to the film forming chamber by the transport tube, and the outer peripheral side of the transport tube in the ultrafine particle production chamber The inert gas in the suction pipe provided in the pipe is sucked and discharged by a vacuum pump, sent to the inert gas purification / recycling system, discharged from the inert gas purification / recycling system, and a purity of 99.9999% or more. and turned, the pattern forming method of the conductive metal thick film according to claim 1 to be returned to the nanoparticle generation chamber.

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