JP2015230846A - Method and apparatus for annealing treatment of transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus which achieves both improvement of the transparency of a transparent conductive film, such as ITO, and resistance reduction.SOLUTION: A method of an annealing treatment of a transparent conductive film comprises generating water vapor by heating humidification water 16 by a first pressure container 11 for humidification, introducing the water vapor into a second pressure container 12 for annealing, heating the water vapor further in the second pressure container 12 at a temperature higher than the temperature of the inside of the first pressure container 11 to generate unsaturated steam of 100°C or higher so as to adjust the humidity and subjecting a transparent conductive film material in the second pressure container 12 to an annealing treatment at the adjusted humidity and a specified temperature in a prescribed time.

Description

The present invention relates to a method for annealing a transparent conductive film for the purpose of improving the transparency and reducing the resistance of a transparent conductive film such as an ITO film, and an apparatus for carrying out this method.

  Annealing is performed by bringing the material into an annealing furnace for the purpose of removing the distortion of the material caused by thermal processing, recrystallization and interfacial modification, and this processing is used for engineering plastics, glass products, and semiconductors. It is used for manufacturing electronic parts.

  In general, annealing is performed by oxidizing the material by applying thermal energy to the material in an annealing furnace maintained at a high temperature (approximately 700 ° C.) for a certain period of time in order to reduce disturbance and stress in the material crystal. It means a process of aligning impurities and making the crystal energetically more stable.

  In this annealing treatment, a sheathed heater, infrared heater, far-infrared heater or the like is used as a heating means, and these heating means include high temperature annealing, low temperature annealing, vacuum annealing, hydrogen annealing and the like. .

  The transparent conductive film is used in solar cells, touch panels, organic ELs, and the like, and accordingly, high transparency and low specific resistance (series resistance, contact resistance) are required. In the prior art, the transparent conductive film is annealed in order to improve characteristics such as lowering the resistance of the transparent conductive film (see Patent Document 1).

Since the annealing treatment of the transparent conductive film according to the prior art is performed for a predetermined time while keeping the temperature and humidity in one annealing chamber constant, it is difficult to achieve both improvement of transparency and reduction of resistance. In addition, the transparent conductive film is required to be bonded to the plastic substrate at a low temperature in order to form a film on a heat-sensitive plastic substrate, but the conventional annealing treatment cannot satisfy this requirement. .

JP 2013-140684 A

The first problem to be solved by the present invention is a method for annealing a transparent conductive film, which can realize improvement in transparency after applying a transparent conductive film on a substrate and reduction in series resistance and contact resistance. It is to provide.

The first problem to be solved by the present invention is an apparatus for annealing a transparent conductive film, which can realize improvement in transparency after coating a transparent conductive film on a substrate and reduction in series resistance and contact resistance. It is to provide.

  According to a first aspect of the present invention, there is provided a first pressure vessel for humidification and a second pressure vessel for annealing for receiving water vapor from the first pressure vessel and annealing the transparent conductive film material. In the second pressure vessel, the water vapor is heated at a temperature higher than the temperature in the first pressure vessel to generate unsaturated water vapor of 100 ° C. or higher to adjust the humidity, and the transparent conductive film material An object of the present invention is to provide a method for annealing a transparent conductive film, characterized by annealing for a predetermined time at the adjusted humidity.

  The second problem-solving means of the present invention includes a first pressure vessel for humidification, a second pressure vessel for annealing that receives water vapor from the first pressure vessel and anneals the transparent conductive film material, and the first pressure vessel. Temperature control means for controlling the temperature in the first pressure vessel and the temperature in the second pressure vessel, the first pressure vessel generates saturated steam at a predetermined temperature by the temperature control means, The second pressure vessel heats the water vapor received from the first pressure vessel by the temperature control means at a temperature higher than the temperature in the first pressure vessel to produce unsaturated water vapor of 100 ° C. or higher, An object of the present invention is to provide an apparatus for annealing a transparent conductive film, wherein the transparent conductive film material is annealed with the unsaturated water vapor.

  In the second problem-solving means, the first pressure vessel includes humidified water therein, a humidified space temperature sensor that measures the temperature on the humidified water, and a first heater that heats the humidified water. The humidifying space temperature sensor inputs a measured temperature to the temperature control means, and the first heater is driven by the temperature control means based on the measured temperature of the humidified water. it can.

  In the second problem-solving means, the second pressure vessel includes an annealing temperature sensor for measuring the temperature of water vapor in the second pressure vessel, and the temperature in the second pressure vessel is determined from the temperature of the water vapor. The annealing temperature sensor inputs the measured temperature to the temperature control means, and the second heating heater sets the measured temperature for annealing. On the basis of this, it can be driven by the temperature control means.

  The first pressure vessel for humidification and the second pressure vessel for annealing are connected by first piping means for moving water vapor generated in the first pressure vessel to the second pressure vessel, Moreover, it can be set as the form connected by the 2nd piping means which moves the water vapor | steam which became 100 degrees C or less inside the 2nd pressure vessel into the 1st pressure vessel.

  According to the present invention, as described above, the water vapor generated in the first pressure vessel and moved to the second pressure vessel is heated by the second heater and further raised in temperature to 100 ° C. The above-described unsaturated water vapor is maintained, and the temperature after annealing the transparent conductive film is maintained for a predetermined time, thereby improving the transparency and low resistance of the transparent conductive film material in the second pressure vessel for annealing. Can be achieved.

  When a transparent conductive film material such as ITO is annealed by the method of the present invention, both high transparency and low resistance can be achieved, and therefore it can be suitably used for touch panels, solar panels, LEDs, and the like. Furthermore, since the thickness of the transparent conductive film (especially ITO) can be reduced, the amount of expensive materials used can be reduced, and since it can be processed at low temperatures, a transparent conductive film material is applied. Since a material having a low heat resistance of 150 ° C. or less, such as plastic, can be selected as the substrate material to be manufactured, the cost of the product can be reduced.

It is a systematic diagram of the apparatus which implements the annealing treatment method of the transparent conductive film by one embodiment of this invention. FIG. 2 is a transition diagram of temperature and humidity when annealing a transparent conductive film using the apparatus of FIG. 1. It is a graph of the humidity dependence of the transmittance | permeability of the transparent conductive film annealed by the method of this invention. It is a graph of the time dependence of the transmittance | permeability of the transparent conductive film annealed by the method of this invention. It is a graph of the temperature dependence of the transmittance | permeability of the transparent conductive film annealed by the method of this invention. It is a simplified diagram of process conditions when carrying out the method of the present invention. It is a graph which shows the resistance value according to process conditions of FIG. 6, and the characteristic of transparency.

The annealing method for a transparent conductive film according to one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an annealing apparatus for a transparent conductive film suitable for carrying out the method of the present invention. Shows systematically.

The annealing apparatus for transparent conductive film includes a first pressure vessel 11 for humidification that retains humidified water 16 therein to generate water vapor, and receives water vapor from the first pressure vessel 11 to receive a transparent conductive film material. A second pressure vessel 12 for annealing, and a temperature control means 18 for controlling the temperature in the first pressure vessel 11 and the temperature in the second pressure vessel 12.

  The first pressure vessel 11 for humidification includes a humidified space temperature sensor 19 that measures the temperature of the space above the humidified water 16 (temperature in the pressure vessel 11), a first heater 17 that heats the humidified water 16, and The humidifying space temperature sensor 19 inputs the measured temperature to the temperature control means 18, and the first heater 17 is driven by the temperature control means 18 based on the measured temperature in the pressure vessel 11 to be humidified water 16. Is heated to generate water vapor of 100 ° C. or higher.

  The second pressure vessel 12 heats the annealing temperature sensor 22 for measuring the annealing temperature in the second pressure vessel 12 and the annealing temperature in the second pressure vessel so as to be higher than the temperature of the water vapor. The annealing temperature sensor 22 inputs the measured temperature to the temperature control means 18, and the second heating heater 21 is driven by the temperature control means 18 based on the measured annealing temperature. Thus, the temperature in the second pressure vessel 12 is raised above the humidified space temperature, and the inside of the second pressure vessel 12 is made an atmosphere of unsaturated steam.

  The first pressure vessel 11 for humidification and the second pressure vessel 12 for annealing are formed by the first piping means 20 that moves the water vapor generated in the first pressure vessel 11 to the second pressure vessel 12. It is connected by the second piping means 23 that is connected and moves the water vapor that has become 100 ° C. or lower inside the second pressure vessel 12 into the first pressure vessel 11.

The second pressure vessel 12 for annealing is automatically exhausted when the internal pressure of the second pressure vessel 12 and the exhaust valve 13 that closes and exhausts the air inside the first pressure vessel 12 and then closes are abnormal. A working safety valve 14 and a pressure gauge 15 for measuring the internal pressure of the second pressure vessel 12 are provided.

The first pressure vessel 11 for humidification is supplied with humidified water 16 in response to an instruction to start an annealing process from a program control device (not shown), and at the same time, temperature adjusting means is applied to the first heater 17 for humidified water. Power is supplied from 18 and heating of the humidified water 16 is started.

The temperature adjusting means 18 controls the heating of the first heater 17 for humidified water until the humidified space temperature sensor 19 that measures the temperature of the space above the humidified water reaches the target humidified space temperature. The temperature of the humidified water 16 inside the first pressure vessel 11 for humidification rises, and the vapor generated by vaporization is annealed from the first pressure vessel 11 for humidification through the first pipe 20. Move into the second pressure vessel.

The temperature adjusting means 18 controls the heating of the second heater 21 until the target annealing temperature is reached by the second temperature sensor 22 that measures the temperature in the second pressure vessel 12 for annealing. Accordingly, the water vapor moved into the second pressure vessel 12 for annealing is further heated by the second heater 21 in the second pressure vessel 12 to become high-temperature unsaturated water vapor whose humidity is adjusted. .

The humidity-adjusted high-temperature unsaturated water vapor is cooled and liquefied during the annealing process in the second pressure vessel 12 for annealing, and the second pressure vessel for annealing passes through the second pipe 23. From 12, the humidifier also returns to the first pressure vessel 11.

Thus, after the water vapor | steam produced | generated in the 1st pressure vessel 11 moves in a 2nd pressure vessel, and becomes an unsaturated water vapor | steam by further heating, it liquefies and returns to the 1st pressure vessel 11 While repeating the cycle, the humidified space temperature in the first pressure vessel 11 and the annealing temperature in the second pressure vessel 12 rise toward the set target value.

Such an annealing process environment is formed by a program process of a program control device (not shown). That is, according to an instruction from the program control device, an instruction to start the annealing process, heating of the first and second heaters 17 and 21 from room temperature, an increase in temperature, exhaust in the second pressure vessel 12, and circulation of water vapor The humidification space temperature and the annealing temperature are raised to the target values necessary for the annealing process, and the annealing state at a predetermined temperature and a predetermined humidity can be maintained for a predetermined time. Natural convection is generated by the high-temperature unsaturated water vapor whose humidity is adjusted in the second pressure vessel 12, and the transparent conductive film material 25 carried on the table 24 in the second pressure vessel 12 for annealing is Annealed.

FIG. 2 shows the transition of the annealing temperature and humidity set for the annealing treatment of the transparent conductive film of the present invention. In response to the instruction to start annealing, the temperature is raised from the normal temperature in the second pressure vessel 12. While increasing the humidity and pressure, the annealing setting condition is reached at time (2-1). As preferable annealing setting conditions, for example, for a transparent conductive film test material 25 formed by applying ITO to a sapphire substrate by an electron beam (EB) evaporation method to a thickness of 50 nm, a predetermined temperature of 140 ° C. is used. A predetermined humidity of 85% and a predetermined pressure of about 0.3 MPa are appropriate, and the annealing treatment of this material is performed while maintaining this condition for 5 hours. At the time (2-2), the annealing is completed, and then the power supply to the first and second heaters 17 and 21 is stopped, the temperature is returned to room temperature, and the pressure and humidity are lowered.

  FIG. 3 shows the humidity dependency of the transmittance of the material 25 when the transparent conductive film test material 25 is carried into the second pressure vessel 12 for annealing and subjected to the annealing treatment. It is the measurement result of the transmittance | permeability at the time of changing annealing humidity from 3% to 85%, maintaining the temperature conditions of 140 degreeC. From this measurement result, it can be seen that the transmittance increases as the humidity increases. This is because as the humidity increases, the oxidation deficiency inside the ITO material decreases and the transmittance increases due to the decrease in carriers.

  FIG. 4 shows the time dependency of the transmittance of the material 25 when the same test material is used and the test material is carried into the second pressure vessel 12 for annealing and annealed. These are the measurement results of the transmittance when the test time was changed from 0 to 10 hours while maintaining the annealing temperature of 140 ° C. and the annealing humidity of 85%. From this measurement result, it is understood that the transmittance becomes the maximum value after 5 hours. This means that 5 hours are required until the oxidation reaction inside the ITO material is activated.

  FIG. 5 shows the temperature dependence of the transmittance when the same test material is used and the test material is carried into the second pressure vessel 12 for annealing and subjected to the annealing treatment. It is the measurement result of the transmittance | permeability at the time of changing annealing temperature from 100 degreeC to 130 degreeC, maintaining the annealing time of time and 85% of annealing humidity. From this measurement result, it can be seen that when the annealing temperature is changed from 120 ° C. to 130 ° C., the transmittance increases. This means that a temperature of 130 ° C. or higher is required for the occurrence of an oxidation reaction inside the ITO material.

  When performing annealing using the apparatus of the present invention, the test temperature (annealing temperature) and test when performing only the oxidation reaction, or performing the test in various steps by combining the oxidation reaction and the crystallization reaction. Process conditions such as humidity (annealing humidity) and test time (annealing time) are shown in FIG. Process A performs only the oxidation reaction process, Process B performs the crystallization process after the oxidation reaction process, Process C performs the oxidation reaction process after the crystallization process, and finally the crystallization process, and Process D includes The oxidation reaction step is performed after the crystallization step. The test temperature (annealing temperature) in the crystallization process is 140 ° C., the test humidity (annealing humidity) is 3% or less, which is almost zero, and the test temperature (annealing temperature) in the oxidation reaction process is 140 ° C. The test humidity (annealing humidity) is 85% and the pressure is 0.3 MPa.

  FIG. 7 shows the results of the resistance value and the transparency in each process for each process in FIG. Process A is a case where only the oxidation reaction process is performed, and this is a phenomenon in which water molecules of unsaturated water vapor are ionized and bonded to oxygen atoms at a location where oxygen atoms are deficient inside the transparent conductive film material. The transparency is about 80%, but the resistance is a little lower than 1Ω. Next, Step B is a case where a crystallization step is added after the oxidation reaction step. This is because the positions of atoms due to thermal energy are in a regular state with small gaps inside the transparent conductive film material, and the transparency is slightly lowered. However, it can be seen that the resistance value further decreases. Process C is a case where the crystallization process is added to the previous stage of Process B, and it can be seen that the resistance value is reduced by one digit or more from Process B. This is an effective means for reducing the resistance when the crystallization process is in the previous stage of the oxidation reaction process. Finally, the process D is a case where the crystallization process after the process C is deleted, and the subsequent crystallization process is unnecessary for reducing the resistance.

  From the above results, by using the annealing apparatus for transparent conductive film of the present invention, the annealing (test) temperature, the annealing (test) humidity, and the annealing (test) time are controlled in order, so that the temperature is low (approximately 140 ° C.). In addition, it is possible to improve the transparency of ITO and to reduce the series resistance and contact resistance. This is based on the fact that unsaturated water vapor generated in the pressure vessel 12 has an extremely strong oxidizing action, and the oxidizing action oxidizes ITO in an oxygen-deficient state at a low temperature. In the above description, the results of testing the ITO transparent conductive film have been described. However, it has been confirmed that other transparent conductive films such as ZnO, InGaZnO, and GaZnO can obtain similar results. . Moreover, although the case where the transparent conductive film was formed by vapor deposition was described in the above description, the present invention can be similarly applied to a transparent conductive film formed by a method other than vapor deposition such as sputtering.

  According to the method of the present invention, it is possible to reduce the series resistance and the contact resistance while realizing the same transparency as that of the conventional manufacturing method. Therefore, the cost of the product can be reduced and it can be used industrially advantageously.

DESCRIPTION OF SYMBOLS 11 1st pressure vessel 12 for humidification 2nd pressure vessel 13 for annealing Exhaust valve 14 Safety valve 15 Pressure gauge 16 Humidification water 17 1st heater 18 for humidification water heating Temperature control means 19 1st temperature sensor 20 1st piping 21 2nd heater 22 for water vapor | steam heating 2nd temperature sensor 23 2nd piping 24 Material stand 25 Transparent electrically conductive film material

Claims (5)

A first pressure vessel for humidification and a second pressure vessel for annealing that receives water vapor from the first pressure vessel and anneals the transparent conductive film material are prepared, and the first pressure vessel is provided in the second pressure vessel. The water vapor is heated at a temperature higher than the temperature in the pressure vessel 1 to produce unsaturated water vapor of 100 ° C. or higher to adjust the humidity, and the transparent conductive film material is predetermined at the predetermined temperature at the adjusted humidity. A method for annealing a transparent conductive film, characterized by performing a time annealing treatment.   A first pressure vessel for humidification; a second pressure vessel for annealing that receives water vapor from the first pressure vessel to anneal the transparent conductive film material; a temperature in the first pressure vessel; Temperature control means for controlling the temperature in the second pressure vessel, the first pressure vessel generates saturated steam at a predetermined temperature by the temperature control means, and the second pressure vessel is the temperature control device. The steam received from the first pressure vessel by means is heated at a temperature higher than the temperature in the first pressure vessel to generate unsaturated steam at 100 ° C. or higher, and the transparent conductive film material is used as the unsaturated steam. An apparatus for annealing a transparent conductive film, characterized in that the annealing process is performed by: 3. The transparent conductive film annealing apparatus according to claim 2, wherein the first pressure vessel has humidified water therein, a humidified space temperature sensor for measuring a temperature on the humidified water, and the humidified water. A first heating heater for heating, the humidification space temperature sensor inputs a measured temperature to the temperature control means, and the first heating heater is configured to control the temperature control means based on the measured temperature of the humidified water. A transparent conductive film annealing apparatus, which is driven by:   The transparent conductive film annealing apparatus according to claim 2 or 3, wherein the second pressure vessel includes a second temperature sensor for annealing that measures a temperature of water vapor in the second pressure vessel; A second heater that heats the temperature in the second pressure vessel so as to rise above the temperature of the water vapor, and the second temperature sensor for annealing has a temperature measured by the temperature control means. , And the second heater is driven by the temperature control means based on the measured temperature of the annealing. 5. The transparent conductive film annealing apparatus according to claim 2, wherein the first pressure vessel for humidification and the second pressure vessel for annealing are in the first pressure vessel. The water vapor generated in step (b) is connected by the first piping means that moves the water vapor to the second pressure vessel, and the water vapor that has become 100 ° C. or less inside the second pressure vessel is moved into the first pressure vessel. A transparent conductive film annealing apparatus characterized by being connected by a second piping means.

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