JP2015153669A - Method for forming transparent conductive film and device for heating and drying thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a transparent conductive film that can improve electric conductivity when forming a transparent conductive film using PEDOT/PSS and to provide a device for drying a transparent conductive film (thin film).SOLUTION: A method for forming a transparent conductive film comprises subjecting a coating film formed by applying a coating material produced by incorporating a conductive polymer material including polyethylene dioxythiophene (PEDOT) and polystyrene sulfonate (PSS) into water as a solvent onto a base material to be treated, to heating and drying treatment in a chamber to dry the coating film and form a transparent conductive film on the base material to be treated. The heating and drying treatment comprises performing drying retardation treatment for suppressing evaporation of a solvent in the coating film in the chamber while maintaining at a drying temperature higher than the boiling point of the solvent and then performing drying acceleration treatment for accelerating evaporation of the solvent.

Description

  The present invention relates to a method for forming a transparent conductive film used for liquid crystals, organic EL (organic electroluminescence), flat panel displays, solar cells and the like, and a thin film heating and drying apparatus.

  A transparent conductive film is a thin film having both visible light transparency and electrical conductivity, and is used as a transparent electrode for liquid crystals, organic EL (organic electroluminescence), flat panel displays, solar cells, and the like. This transparent conductive film is made of indium oxide or tin oxide, and is generally formed by sputtering. ITO formed by this sputtering method has a problem that it is difficult to apply to a film or the like because of high manufacturing cost and weakness to bending.

  In order to solve this problem, in recent years, a conductive polymer material of polyethylene dioxythiophene / polystyrene sulfonic acid (referred to as PEDOT / PSS) has been applied as a transparent conductive film (for example, see the following patent document). . The transparent conductive film formed of PEDOT / PSS is excellent in electrical conductivity and has a characteristic that it is more resistant to bending than ITO. This PEDOT / PSS transparent conductive film is obtained by applying a solution obtained by adding about 5% by mass of a high boiling point solvent such as dimethyl sulfoxide to a PEDOT / PSS dispersion on a substrate to be treated using a coating apparatus such as a spin coater or a slit coater. It is formed by applying and drying the formed coating film with a heat drying apparatus.

  This heating / drying apparatus is a general heating / drying apparatus, and as shown in FIG. 5, a chamber 100 that accommodates the substrate W to be processed, and a sheet-like heating apparatus 101 that sets the inside of the chamber 100 to a predetermined temperature. And an exhaust unit 102 that exhausts the inside of the chamber 100 and a gas supply unit 103 that supplies a gas such as the atmosphere or an inert gas into the chamber 100. That is, the heat drying is performed by maintaining the state in which the substrate to be processed W is accommodated in the chamber 100 set to the drying temperature at which the solvent evaporates, and thereby the coating film C is heated. When the coating film C is heated, the solvent evaporates from the coating film C, and the evaporated solvent is exhausted from the exhaust unit 102, so that the drying of the coating film C is accelerated. By holding in this state for a predetermined time, the heating and drying of the coating film C is completed, and a transparent conductive film is formed on the substrate W to be processed.

JP 2009-078443 A

  However, the transparent conductive film formed by PEDOT / PSS has a problem that its electrical conductivity is inferior to that of ITO. That is, PEDOT / PSS, which is a conductive polymer material, improves electrical conductivity by adding about 5% by mass of a high-boiling solvent. However, in the manufacturing method using the heating and drying apparatus, the level is equivalent to that of ITO. As a result, the transparent conductive film formed of PEDOT / PSS has a problem that it is difficult to achieve the target of electrical conductivity although it is strong against physical changes such as bending.

  The present invention has been made in view of the above problems, and a method of forming a transparent conductive film and a transparent conductive film (thin film) that can improve electrical conductivity when forming a transparent conductive film using PEDOT / PSS. The object is to provide a drying device.

  In order to solve the above-mentioned problems, the transparent conductive film forming method of the present invention is a coating in which a conductive polymer material containing polyethylenedioxythiophene (PEDOT) and polystyrenesulfonic acid (PSS) is contained in water as a solvent. A transparent conductive film for forming a transparent conductive film on a substrate by drying the coating film by heating and drying a coating film formed by applying a material on the substrate to be processed. In the forming method, the heat drying treatment promotes the evaporation of the solvent after the drying delay treatment is performed in the chamber to suppress the evaporation of the solvent of the coating film while being held at a drying temperature equal to or higher than the boiling point of the solvent. It is characterized in that drying acceleration processing is performed.

  According to the method for forming a transparent conductive film, in the heat drying process of the coating film, a drying delay process is performed in which the evaporation of the solvent of the coating film is suppressed in the chamber while maintaining the drying temperature higher than the boiling point of the solvent. Thereby, electrical conductivity can be improved. This phenomenon is exposed to a situation in which the coating film is difficult to dry at high temperature, and therefore, the flow toward crystallization of PEDOT / PSS can be activated in the undried coating film. Then, after a drying delay treatment is performed for a predetermined time, a drying acceleration treatment is performed, whereby the PEDOT / PSS molecular arrangement that was initially disordered is dried in an aligned state, and a transparent conductive film is formed. Therefore, since the PEDOT / PSS molecules can be dried in an aligned state as compared with the conventional method in which only the heat treatment (drying acceleration treatment) is performed without performing the heat delay treatment, the electrical conductivity of the transparent conductive film is improved. It is thought to improve.

  Further, as a specific aspect of the drying delay treatment, the chamber can be maintained at the saturated vapor pressure of the solvent and dried at the drying temperature.

  According to this configuration, by maintaining the inside of the chamber at the saturated vapor pressure of the solvent, evaporation of the solvent of the coating film can be suppressed, and drying of the coating film can be delayed.

  The drying delay process may be performed by supplying a solvent into the chamber.

  According to this configuration, even if the amount of the solvent in the coating film is less than the amount for reaching the saturated vapor pressure in the chamber, the supplied solvent is evaporated to reach the saturated vapor pressure in the chamber. be able to.

  As another specific mode of the delayed drying process, the pressure in the chamber may be maintained at a pressure higher than the atmospheric pressure and dried at the drying temperature.

  According to this configuration, the boiling point of the solvent is increased by maintaining the pressure in the chamber at a pressure higher than the atmospheric pressure, so that drying can be delayed as compared with the case of drying at atmospheric pressure.

  In order to solve the above problems, the thin film heating and drying apparatus of the present invention includes a chamber for storing a substrate to be processed on which a coating film is formed by applying a coating material, and a processing target stored in the chamber. A heating device that heats the coating film on the substrate; and a drying control valve that adjusts a drying atmosphere in the chamber, wherein the drying control valve is held at a drying temperature equal to or higher than the boiling point of the solvent. In this state, the drying chamber is adjusted to a drying atmosphere of a drying delay process that suppresses evaporation of the solvent of the coating film and a drying atmosphere of a drying acceleration process that promotes evaporation of the solvent.

  According to the above thin film forming apparatus, since the drying control valve is provided, the drying atmosphere of the delayed drying process that suppresses evaporation of the solvent of the coating film in the chamber while maintaining the drying temperature higher than the boiling point of the solvent is easy. Can be formed. As a result, the coating film is heated while suppressing evaporation of the solvent, so that the coating film is exposed to a high temperature in a state where it is difficult to dry. Therefore, in the undried coating film, the crystallization of PEDOT / PSS The flow can be made active. A transparent conductive film with good electrical conductivity can be formed by promoting drying in a state where the molecular arrangement of PEDOT / PSS is aligned.

  Further, as a specific aspect of the drying control valve, the chamber is maintained at the saturated vapor pressure of the solvent by being adjusted to the closed state in the drying delay processing, and is opened in the drying acceleration processing. By being adjusted, the configuration can be such that the evaporated solvent in the chamber is discharged.

  According to this configuration, when the drying delay process is performed, the chamber can be sealed by closing the drying control valve. Therefore, when the coating film is heated, the solvent evaporates and the inside of the chamber is filled with the solvent. Saturated vapor pressure can be achieved. That is, by forming the inside of the chamber at the saturated vapor pressure of the solvent, evaporation of the solvent of the coating film can be suppressed, and drying of the coating film can be delayed.

  As another specific aspect of the drying control valve, in the drying delay process, the chamber may be adjusted from the closed state to the open state while maintaining the saturated vapor pressure of the solvent.

  According to this configuration, the drying adjustment valve is adjusted from the closed state to the open state, so that the drying can be gradually shifted to the drying promotion process while the drying is delayed by the drying delay process. Uneven drying due to changes can be suppressed.

  According to the transparent conductive film forming method and thin film heating and drying apparatus of the present invention, electrical conductivity can be improved when a transparent conductive film is formed using PEDOT / PSS.

It is the schematic which shows the open state of the chamber of the thin film heating drying apparatus in this embodiment. It is the schematic which shows the closed state of the chamber of the said thin film heating drying apparatus. It is a block diagram which shows the operation | movement flow in each process of the said thin film heating drying apparatus. It is a graph which shows the relationship between a drying temperature and a surface resistance value about the Example of the transparent conductive film manufactured using the said thin film heating drying apparatus, and its comparative example. It is a figure which shows the conventional thin film heating drying apparatus.

  Next, an embodiment of the thin film heating and drying apparatus 1 of the present invention will be described. Here, FIG. 1 is a schematic view showing the open state of the chamber of the thin film heating and drying apparatus 1 in the present embodiment, and FIG. 2 is a schematic view showing the closed state of the chamber of the thin film heating and drying apparatus 1.

  As shown in FIGS. 1 and 2, the thin film heating and drying apparatus 1 is a coating film C formed on a substrate W to be processed in order to form a transparent conductive film used for liquid crystals, organic EL, solar cells, and the like. Is to be dried. That is, by applying a coating material in which a conductive polymer material of polyethylene dioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) is dispersed in water, a coating film C is formed on the substrate W to be treated. This coating film C is dried.

  The thin film heating and drying apparatus 1 has a chamber 2 that accommodates the substrate to be processed W, and the substrate to be processed W is dried by heating the inside of the chamber 2. A transparent conductive film containing PEDOT / PSS can be formed.

  The chamber 2 of the thin film heating and drying apparatus 1 includes a base material placement unit 20 and a chamber lid 10 that can be opened and closed, and the chamber lid 10 is closed with respect to the base material placement unit 20. Thus, a housing portion 30 (see FIG. 2; also referred to as the inside of the chamber 2) for housing the substrate to be processed W is formed.

  The substrate mounting portion 20 is formed in a flat plate shape having a larger surface area than the substrate to be processed W, and the substrate to be processed W on which the coating film C is formed is mounted. Specifically, the substrate mounting portion 20 is provided with a substrate lifting mechanism that moves the substrate W to be processed up and down, and maintains the posture in which the substrate W is supplied by the substrate lifting mechanism. It is mounted as it is. In the present embodiment, a plurality of pin holes 22 are formed in a region where the substrate to be processed W is placed on the placement surface 21 on which the substrate to be treated W of the substrate placement unit 20 is placed. The pin hole 22 is embedded with a lift pin 40 that can be moved up and down in the Z-axis direction. A driving device 41 is connected to the lift pin 40, and the driving device 41 is driven so that the lift pin 40 protrudes from the placement surface 21 to a predetermined height position (upward position). As a result, when the substrate to be processed W is placed on the placement surface 21, the supplied substrate to be treated W is held at the tip portion of the lift pin 40 with the lift pin 40 raised to the raised position. The substrate W to be treated can be placed on the placement surface 21 by lowering the lift pins 40 from this state.

  In addition, the substrate placement unit 20 is provided with a heater 51 which is a heating device 50. The heater 51 is formed in a sheet shape, and is embedded in the base material placement unit 20 so as to be parallel to the placement surface 21. In the present embodiment, for example, a mica heater is provided as the heater 51, and by operating the heater 51, the entire surface of the substrate mounting portion 20 is heated and the entire substrate to be processed W is heated. The control of the heater 51 is performed by a control device to be described later, and the substrate to be processed W is maintained at a set temperature by the control device.

  The chamber lid portion 10 has a shape that covers the substrate W to be processed placed on the placement surface 21, a flat plate portion 11 that faces the placement surface 21, and an edge at the end of the flat plate portion 11. It has the accommodating wall part 12 which protrudes in the mounting surface 21 side from the part 11a.

  The flat plate portion 11 is formed in a shape corresponding to the shape of the substrate W to be processed, that is, a rectangular shape. The flat plate portion 11 is formed with a constant thickness, and the surface (substrate mounting portion side surface 11b) facing the mounting surface 21 is substantially parallel to the mounting surface 21 and formed flat. Yes. The accommodating wall 12 is formed to extend from the four edge portions 11a of the flat plate portion 11 to the placement surface 21 side, and is formed so as to surround the placed substrate W to be treated. That is, the housing wall portion 12 is formed so as to protrude from the edge portion 11 a perpendicular to the flat plate portion 11.

  The chamber lid 10 is configured to move up and down. That is, the chamber lid portion 10 is provided with a driving device 7, and by driving the driving device 7, the chamber lid portion 10 can come into contact with and separate from the placement surface 21 of the base material placement portion 20. It has become. The bottom surface 12 a of the storage wall portion 12 is formed so as to be substantially parallel to the placement surface 21, and the substrate W to be treated is placed on the bottom surface 12 a of the storage wall portion 12 and the surface of the placement surface 21. The container 30 (inside the chamber 2) is hermetically sealed by contacting the sealing member 13 provided so as to surround it. That is, when the driving device 41 is driven to lower the chamber lid 10, the bottom surface 12 a of the housing wall 12 and the sealing material 13 are brought into close contact with each other, whereby the housing 30 and the outside thereof are blocked by the sealing material 13 and closed. It becomes a state. Thereby, the accommodating part 30 (inside the chamber 2) is sealed.

  The chamber lid 10 is provided with a heater 52 which is a heating device 50. In other words, the heating device 50 is formed by the heater 51 of the base material placement unit 20 and the heater 52 of the chamber lid unit 10. The heater 52 of the chamber lid 10 is formed in a sheet shape, and is embedded in accordance with the shape of the chamber lid 10. Specifically, the heater 52 is embedded in the flat plate portion 11 and the accommodating wall portion 12 of the chamber lid portion 10. That is, the heater 52 is provided so that the to-be-processed base material W in the chamber 2 is covered when the chamber lid part 10 is closed. The heater 52 of the chamber lid portion 10 is also provided with a mica heater, and the temperature is controlled by a control device. And if the heater 52 is operated by a control apparatus, the coating film C formed in the to-be-processed base material W will be maintained by preset temperature (drying temperature). That is, the temperature is maintained at a temperature equal to or higher than the boiling point of water, which is a solvent of the coating material for forming the coating film C of the substrate W to be treated.

  In addition, the chamber lid 10 is provided with a drying control valve 60. This drying adjustment valve 60 is for adjusting the drying atmosphere in the chamber 2. The drying control valve 60 can be connected to and disconnected from the inside of the chamber 2 and the exhaust pipe 61 by opening and closing. That is, by opening the drying control valve 60, the inside of the chamber 2 and the exhaust pipe 61 communicate with each other and the inside of the chamber 2 is exhausted. Further, by closing the drying control valve 60, the inside of the chamber 2 and the exhaust pipe 61 are shut off, and the inside of the chamber 2 can be maintained in a sealed state. The drying control valve 60 is configured such that its opening / closing body is controlled by a control device described later, and the drying atmosphere in the chamber 2 can be adjusted by controlling the opening / closing state. ing.

  Further, the thin film heating and drying apparatus 1 is provided with a control device, and each drive device is controlled by the control device. Specifically, the control device controls the driving device 7 that moves the chamber lid 10 up and down and the driving device 41 that drives the lift pins 40 of the substrate lifting mechanism to move up and down, and drives them appropriately. The control device drives and controls the opening / closing operations of the heaters 52 and the drying control valve 60.

  In the present embodiment, the control device can adjust the inside of the chamber 2 to a predetermined temperature by controlling the heating device 50 (heater 52). That is, by adjusting the output of the heater 52, the temperature is adjusted to the drying temperature at which the solvent of the coating film C formed on the substrate to be processed W evaporates. Specifically, since the solvent of the coating material containing polyethylene dioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) is water, the control device is set so that the temperature of the solvent becomes 100 ° C. or more which is the boiling point of water. The heater 52 is adjusted. The set temperature of the heater 52 at this time is called a drying temperature. That is, when the drying temperature is set to 100 ° C., the heater 52 is adjusted so that the temperature of the coating film C becomes 100 ° C.

  Further, the control device adjusts the drying atmosphere in the chamber 2 by controlling the opening / closing operation of the drying control valve 60. Specifically, the drying atmosphere in the chamber 2 is adjusted by adjusting the opening ratio of the drying control valve 60 from the closed state (closed state) to the fully opened state. For example, when the drying control valve 60 is closed, the inside of the chamber 2 is hermetically sealed, so there is no escape space for the solvent that evaporates during heating, and the chamber 2 can be formed in a state that is difficult to dry. On the other hand, the evaporation of the solvent of the coating film C can be promoted by opening the drying control valve 60. That is, the drying acceleration state can be adjusted by adjusting the opening ratio of the drying control valve 60.

  Here, a series of heating and drying programs are stored in the control device, and each driving device, the heater 52, and the drying adjustment valve 60 are controlled according to the heating and drying program. In this embodiment, a heat drying program based on the drying delay process and the drying acceleration process is stored.

  The drying delay process is a process that intentionally delays the drying while activating the molecules forming the coating film C. That is, heating of the coating film C activates molecular activity, and prevents evaporation of the solvent in the coating film C, thereby delaying drying of the coating film C. In the present embodiment, the coating film C is heated and dried by the heating device 50 with the chamber 2 sealed. Specifically, the control device controls the heaters 51 and 52 as the heating device 50 to be heated by closing the drying adjustment valve 60. Thereby, the coating film C on the to-be-processed base material W is heated, and a solvent evaporates. And when the inside of the chamber 2 reaches the saturated vapor pressure of the solvent, the evaporation of the solvent and the reaction of returning the vaporized solvent to the liquid are in an equilibrium state. That is, promotion of solvent evaporation is suppressed, and the solvent in the chamber 2 is formed in an atmosphere that is difficult to dry. In this state, since the molecular activity is promoted by heating in the presence of the solvent in the coating film C, the molecules can move almost freely, and the molecular arrangement forming the coating film C is aligned. Conceivable. Therefore, holding this state for a certain period of time is considered to be a factor in which disordered molecular arrangements are aligned and conductivity is improved. This fixed time is a time required for performing molecular alignment, is determined by the type of coating material, the thickness of the coating film C, and the amount of solvent, and is obtained in advance through experiments or the like.

  Note that the drying control valve 60 in the drying delay process may form an atmosphere that is difficult to dry by closing as described above, but by gradually opening the drying control valve 60 from the closed state. An atmosphere that is difficult to dry may be formed. That is, the opening ratio of the drying control valve 60 may be adjusted so that the amount of the exhausted solvent evaporated is smaller than the evaporation amount of the solvent generated when the coating film C is heated. This method of gradually opening is preferable because it can smoothly shift to a drying acceleration process described later, and can prevent drying unevenness due to a sudden change when shifting from a drying delay process to a drying acceleration process.

  Further, the drying promotion process is a normal heat drying process, and is a process of actively promoting drying by promoting evaporation of the solvent of the coating film C while heating. Specifically, the control device controls the drying control valve 60 to be opened so that the coating film C is heated by the heating device 50 and dried. As a result, the solvent evaporated by evaporation is exhausted through the drying control valve 60, and thus drying of the coating film C is promoted. By holding this state for a certain time, the solvent of the coating film C evaporates and the drying of the coating film C is completed. Here, the opening / closing ratio of the drying control valve 60 may be gradually opened from the opening / closing state of the drying control valve 60 at the end of the drying delay process, or immediately after the opening / closing state of the drying control valve 60 at the end of the drying delay process. It may be fully opened. That is, when the opening ratio of the drying control valve 60 is gradually opened from the closed state so that the exhaust amount of the vaporized solvent is larger than the evaporation amount of the solvent generated when the coating film C is heated. Since the drying atmosphere in the chamber 2 can be prevented from changing suddenly, the occurrence of drying unevenness based on the rapid change in the drying atmosphere can be suppressed. Similar to the drying delay process, the time required for the drying acceleration process is a time necessary for the molecular arrangement to be performed, and is determined by the type of coating material, the thickness of the coating film C, the amount of the solvent, Sought by.

  Next, the operation of the thin film heating and drying apparatus 1 (a method for forming a transparent conductive film) will be described. Here, FIG. 3 is a configuration diagram showing an operation flow in each process of the thin film heating and drying apparatus 1.

  First, a. In the substrate carrying-in process, the substrate W to be processed is carried into the thin film heating and drying apparatus 1. A coating film C is formed on the substrate W to be processed, and the coating film C is formed on the substrate W to be processed by a coating apparatus such as a slit coater in the upstream process. This coating film C is a thin film formed of a conductive polymer material containing polyethylene dioxythiophene and polystyrene sulfonic acid (PEDOT / PSS) in water. Specifically, the coating material C containing PEDOT / PSS using water as a solvent is discharged from the slit nozzle, and the slit nozzle is scanned to form the coating film C having a uniform thickness on the substrate W to be processed. . And the to-be-processed base material W in which the coating film C was formed is conveyed by conveyance apparatuses, such as a robot hand, and the to-be-processed base material W is mounted in the front-end | tip part of the lift pin 40 which the base material mounting part 20 protruded. Then, by lifting the lift pin 40 and embedding it in the substrate mounting portion 20, the substrate to be processed W is loaded on the mounting surface 21, whereby the substrate to be processed W is carried into the chamber 2. .

  Next, b. A heat drying preparation process is performed. Specifically, the chamber lid 10 is lowered to accommodate the substrate W to be processed on the placement surface 21 in the chamber 2. That is, when the chamber lid 10 is lowered, the inside of the chamber 2 is shut off from the outside of the chamber 2 by the elastic contact of the sealing material 13 of the chamber lid 10 with the base material placement unit 20. At this time, the drying control valve 60 is controlled to be closed. That is, the substrate W to be processed is sealed in the chamber 2.

  Next, c. A drying delay processing step of the heat drying step is performed. Specifically, the heating device 50 is operated and heated while the drying control valve 60 is closed. That is, the coating film C is heated so as to have a drying temperature. In this embodiment, the drying temperature is set to 100 ° C., which is the boiling point of the solvent. When the coating film C is maintained at the drying temperature, the solvent 2 can be prevented from being dried by reaching the saturated vapor pressure in the chamber 2. That is, the coating film C is maintained at the drying temperature for a predetermined time with the solvent remaining in the coating film C.

  Next, d. A drying acceleration treatment step of the heat drying step is performed. Specifically, after being held at the drying temperature for a predetermined time by the drying delay processing step which is a pretreatment, the drying control valve 60 is gradually opened to discharge the vaporized solvent in the chamber 2. That is, by opening the drying control valve 60 while being heated by the heating device 50, the saturated state of the solvent vaporized in the chamber 2 is eliminated. As a result, when the solvent of the coating film C is positively evaporated, the heating and drying of the coating film C is promoted.

  Next, e. A substrate discharging process is performed. Specifically, a drying acceleration treatment process is performed for a certain time, and after the coating film C is dried, the chamber lid 10 is raised and the substrate W to be treated is discharged. That is, the lift pins 40 are raised, the substrate W to be processed is transferred to a transport device such as a robot hand, and the substrate W to be processed is discharged downstream.

  Here, as an example, by applying a coating material containing PEDOT / PSS using water as a solvent, a coating film C is formed on the substrate W to be processed, and the thin film heating and drying apparatus 1 of the above embodiment is used. A transparent conductive film was formed. That is, with respect to the to-be-processed base material W in which the coating film C was formed, the drying delay process and the drying acceleration process were performed by the thin film heating and drying apparatus 1 of the above embodiment. At that time, the drying temperature was 100 ° C. and 200 ° C., and a transparent conductive film having a thickness of 1000 nm after drying was prepared.

  Further, as a comparative example, the same coating material as that of the example was applied and the coating film C was formed on the substrate W to be processed without closing the chamber lid 10 on the substrate mounting portion 20. Normal heat drying was performed. At that time, the drying temperature was 100 ° C. and 200 ° C., and a transparent conductive film having a thickness of 1000 nm after drying was produced.

  The results of measuring surface resistance values for these transparent conductive films are shown in FIG. Here, FIG. 4 is a graph showing the relationship between the drying temperature and the surface resistance value. As can be seen, the surface resistance value of the transparent conductive film (Example) produced by the thin film heating and drying apparatus 1 of the present invention is lower and the conductivity is improved at both the drying temperatures of 100 ° C. and 200 ° C. As for the drying temperature, the rate of decrease in the surface resistance value was larger at 200 ° C. This is because in the delayed drying process, the PEDOT / PSS molecules can be activated more actively when maintained at a high temperature of 200 ° C., so that the aligned body when moving to the drying acceleration process is dried in a better state. This is thought to be due to this.

  Thus, according to the thin film heating and drying apparatus 1 and the method for forming the transparent conductive film in the above embodiment, in the heating and drying treatment of the coating film C, the chamber 2 is kept at a drying temperature higher than the boiling point of the solvent. The electrical conductivity can be improved by performing a drying delay treatment that suppresses evaporation of the solvent of the coating film C. Since this phenomenon is exposed to a situation where the coating film C is difficult to dry at a high temperature, the flow toward the crystallization of PEDOT / PSS can be activated in the undried coating film C. Then, after a drying delay treatment is performed for a predetermined time, a drying acceleration treatment is performed, whereby the PEDOT / PSS molecular arrangement that was initially disordered is dried in an aligned state, and a transparent conductive film is formed. Therefore, since the PEDOT / PSS molecules can be dried in an aligned state as compared with the conventional method in which only the heat treatment (drying acceleration treatment) is performed without performing the heat delay treatment, the electrical conductivity of the transparent conductive film is improved. It is thought to improve.

  Moreover, although the said embodiment demonstrated the case where the drying control valve 60 in a dry delay process was closed completely, even if it forms the atmosphere which is hard to dry by making the drying control valve 60 into an open state gradually from a closed state. Good. Since the method of gradually opening is more smoothly transferred to the drying promotion process described later, drying unevenness due to a rapid change when shifting from the drying delay process to the drying promotion process can be suppressed.

  In the above embodiment, in the drying delay process, the solvent of the coating film C is evaporated to form a saturated vapor pressure environment. However, the amount of the solvent of the coating film C is small, and the chamber 2 reaches the saturated vapor pressure. If not, the chamber 2 may be formed at a saturated vapor pressure by adding water as a solvent from another supply means.

  In the above-described embodiment, the example in which the drying delay process is performed by maintaining the inside of the chamber 2 at the saturated vapor pressure has been described. However, by maintaining the pressure in the chamber 2 at a high pressure, an environment in which the solvent is difficult to evaporate is described. It may be formed.

  Moreover, although the said embodiment demonstrated the example provided with a control apparatus in the thin film heating drying apparatus 1, the control which controls overall manufacturing apparatuses, such as a solar cell and organic EL, separately from the thin film heating drying apparatus 1 was demonstrated. It may be controlled by a device.

DESCRIPTION OF SYMBOLS 1 Thin film heating drying apparatus 2 Chamber 10 Chamber lid part 20 Base material mounting part 30 Chamber 50 Heating apparatus 51 Heater 52 Heater 60 Drying control valve W Substrate to be processed C Coating film

Claims (7)

A coating film formed by applying a coating material containing a conductive polymer material containing polyethylenedioxythiophene and polystyrenesulfonic acid to water as a solvent on a substrate to be treated is heated and dried in a chamber. In the method for forming a transparent conductive film, by drying the coating film to form a transparent conductive film on the substrate to be processed,
In the heat drying process, a drying accelerating process for promoting the evaporation of the solvent is performed after the drying delay process is performed in the chamber to suppress the evaporation of the solvent in the coating film while maintaining the drying temperature equal to or higher than the boiling point of the solvent. A method for forming a transparent conductive film, which is performed.   The method for forming a transparent conductive film according to claim 1, wherein the drying delay treatment is performed at the drying temperature while maintaining the inside of the chamber at a saturated vapor pressure of a solvent.   The method for forming a transparent conductive film according to claim 1, wherein the drying delay process is performed by supplying a solvent into the chamber.   The method for forming a transparent conductive film according to claim 1, wherein the drying delay treatment is performed by drying at the drying temperature while maintaining a pressure in the chamber higher than atmospheric pressure. A chamber for accommodating a substrate to be processed on which a coating film is formed by applying a coating material;
A heating device that heats the coating film of the substrate to be processed contained in the chamber;
A drying control valve for adjusting the drying atmosphere in the chamber;
With
The drying control valve accelerates the evaporation of the solvent, and the drying atmosphere of the drying delay treatment that suppresses the evaporation of the solvent of the coating film in the chamber while the coating film is held at the drying temperature equal to or higher than the boiling point of the solvent. A thin film heating and drying apparatus, wherein the drying atmosphere is adjusted to the drying atmosphere of the drying acceleration treatment.   The drying adjustment valve is adjusted to a closed state in the drying delay process, thereby maintaining the inside of the chamber at a saturated vapor pressure of the solvent, and adjusted to an open state in the drying acceleration process, so that the inside of the chamber is adjusted. The thin film heating and drying apparatus according to claim 5, wherein the evaporated solvent is discharged.   7. The thin film heating drying according to claim 5, wherein the drying adjustment valve is adjusted from a closed state to an open state while maintaining the inside of the chamber at a saturated vapor pressure of a solvent in the drying delay process. apparatus.

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