Heating device and heating method

Abstract

The present invention provides a heating device and a heating method that make it possible to stably produce a thin film with high film quality.　Provided is a heating device that heats a base material on a surface of which is formed a thin film, said heating device comprising: a main heating unit that is capable of short heating of less than one second; an auxiliary heating unit that has a heating mechanism which is capable of longer heating than the main heating unit; a transfer unit that transfers the base material from a first region in which heating is performed by the auxiliary heating unit to a second region in which heating is performed by the main heating unit; a first chamber that accommodates at least the auxiliary heating unit; and a discharge port that is for discharging atmospheric gas which is inside the first chamber.

Description

Heating device and heating method

[0001] The present invention relates to a heating device and a heating method for heating a substrate having a thin film formed on its surface.

[0002] In recent years, perovskite films have been actively researched in the field of solar cells, etc., due to their potential for high photoelectric conversion efficiency. Furthermore, perovskite films can be composed of materials that are highly soluble in solvents, making them suitable for film formation by solution processing.

[0003] For example, Patent Document 1 below proposes that a perovskite film formed by a solution process such as spin coating be instantaneously heated with a flash lamp in order to obtain a perovskite film with higher crystallinity.

[0004] U.S. Pat. No. 1,093,7978

[0005] However, the present inventors have noticed that, as shown in Patent Document 1, if a perovskite film is formed by a solution process and then heated with a flash lamp, problems may occur that deteriorate the film quality of the heated perovskite film.

[0006] In view of the above, an object of the present invention is to provide a heating apparatus and a heating method that can stably produce a high-quality thin film.

[0007] The heating device according to the present invention is a heating device for heating a substrate having a thin film formed on its surface, and is characterized by comprising: a main heating unit capable of short-time heating of less than one second; a preheating unit having a heating mechanism capable of long-time heating than the main heating unit; a transfer unit for transferring the substrate from a first region heated by the preheating unit to a second region heated by the main heating unit; a first chamber accommodating at least the preheating unit; and an exhaust port for exhausting atmospheric gas from within the first chamber.

[0008] In this specification, the term "thin film" refers to a film having a thickness of about 1 nm to 10 μm, which is formed by a solution process such as spin coating, a dropping method, or an inkjet method. Note that the term "thin film" in this specification is a concept that also includes a state in which the solvent used during formation remains.

[0009] This heating unit can instantaneously heat a thin film, such as a perovskite film. As an example, this heating unit is composed of a flash lamp. By instantaneously heating a thin film, such as a perovskite film, with a flash lamp, the film quality of the thin film can be improved.

[0010] In this specification, the term "perovskite film" refers to a film composed of crystals exhibiting a perovskite structure. The perovskite structure is represented by the structural formula ABX, such as CHNHPbI. As an example, in the case of an organometallic halide compound, A is an organic group containing carbon, B is a metal element such as lead, and X is a halogen element such as iodine, chlorine, or bromine. The perovskite structure also includes a so-called double perovskite structure represented by the structural formula ABB'X, where B and B' are two different metal elements.

[0011] By heating a thin film to a high temperature instantaneously, i.e., in a short time of less than one second, the crystals that make up the thin film instantaneously melt. After the crystals melt, they cool and return to a solid state, resulting in a larger crystal size that makes up the thin film. In addition, by heating the thin film instantaneously, it is possible to increase the crystallinity of the thin film while suppressing deterioration of the thin film due to heating to a high temperature.

[0012] However, when heating is performed using a conventional method using a flash lamp for this purpose, defects such as pinholes and cracks (hereinafter sometimes abbreviated as "pinholes, etc.") occur in the perovskite film after heating, and the film quality of the perovskite film may be lower than expected. One reason for this is that the solvent remaining in the perovskite film instantly becomes hot when heated by the flash lamp and boils off.

[0013] Therefore, the inventors investigated reducing the solvent in the perovskite film by pre-heating before instantaneous heating using a flash lamp, etc. Hereinafter, the instantaneous heating step using a flash lamp, etc. will be referred to as "main heating," and the heating step carried out before main heating will be referred to as "pre-heating."

[0014] By pre-heating the perovskite film before the main heating, the amount of solvent in the perovskite film subjected to the main heating is reduced, which is thought to make it less likely for the solvent to bump in the perovskite film and suppress the occurrence of pinholes and other defects during the main heating.

[0015] However, according to intensive research by the present inventors, although preheating reduces the amount of solvent in the perovskite film, it has been found that simply performing preheating tends to cause fluctuations in the amount of solvent evaporated by preheating. If the amount of solvent evaporated by preheating is not stable, the amount of solvent in the perovskite film subjected to main heating will vary, making it impossible to consistently produce a high-quality perovskite film in which, for example, the occurrence of pinholes and the like is suppressed. This problem is primarily caused by variations in the amount of solvent remaining in the thin film after preheating, and is thought to occur not only in perovskite films but also in coated films made of, for example, metal nanoink.

[0016] If preheating is performed in a closed space such as a chamber before the main heating, the solvent vapor evaporated from the thin film by the preheating may accumulate in the chamber. For example, if preheating is performed consecutively in the same chamber, the solvent vapor is likely to accumulate in the chamber.

[0017] If preheating is performed while solvent-derived vapor has accumulated in the chamber, the solvent will be less likely to evaporate from the thin film, and as a result, a large amount of solvent may remain in the thin film despite the preheating. In other words, the accumulation of solvent-derived vapor in the chamber may cause problems such as fluctuations in the amount of solvent evaporated during preheating or a large amount of solvent remaining in the thin film. In particular, if a large amount of solvent remains in the thin film, the solvent may bump, causing defects such as pinholes, and the quality of the thin film may deteriorate.

[0018] In contrast, according to the above configuration, the first chamber has an exhaust port for exhausting the atmospheric gas within the first chamber. Here, the first chamber houses a preheating unit, which has a heating mechanism capable of heating for a longer period of time than the main heating unit. In other words, the first chamber is a chamber capable of performing preheating. By exhausting the vapor derived from the solvent contained in the atmospheric gas, the accumulation of vapor derived from the solvent within the first chamber is suppressed. This stabilizes the amount of solvent evaporated during preheating, thereby reducing variation in the amount of solvent in the thin film subjected to main heating. Therefore, the above heating device suppresses defects such as pinholes in the thin film, enabling the stable production of high-quality thin films.

[0019] Although the above description has been given taking the case where the thin film is a perovskite film as an example, the heating device is not limited to perovskite films and can be suitably used to heat, for example, a coated film of metal nanoink.

[0020] For example, when sintering a metal nanoink coating film, instantaneous heating (corresponding to "main heating") is performed by the main heating unit. If a large amount of the solvent in which the metal nanoparticles were dispersed is present in the coating film, the bumping of the solvent can easily degrade the quality of the sintered coating film. In contrast, by performing preheating using a preheating unit before performing main heating, the amount of solvent in the coating film is reduced, thereby suppressing the occurrence of pinholes and other defects during main heating, and a thin film with high film quality can be obtained. Furthermore, from the perspective of stabilizing the amount of solvent evaporated during preheating, it is preferable to exhaust the vapor derived from the solvent in the first chamber where preheating was performed. Regarding this point, the same discussion as for the perovskite film above is applicable.

[0021] The heating unit may include a light source that emits light with a pulse width of less than 1 second.

[0022] A flash lamp can be suitably used as the light source. Other configuration examples of the heating unit will be described in detail in the section "Mode for Carrying Out the Invention."

[0023] The first chamber accommodates both the preheating unit and the main heating unit, and has a partition wall that substantially separates a first space in which the preheating unit is arranged and the first region is located inside, from a second space in which the main heating unit is arranged and the second region is located inside, while ensuring a transport space for the substrate, and the exhaust port may exhaust atmospheric gas from the first space.

[0024] In the above configuration, the inside of the first chamber is substantially divided into a first space where preheating is performed and a second space where main heating is performed. By substantially dividing the first space and the second space by a partition wall, the atmosphere in the second space is prevented from affecting the first space. This makes it easier to stabilize the temperature and other conditions in the first space, and as a result, the amount of solvent evaporated during preheating is stabilized, thereby suppressing variations in the amount of solvent in the thin film subjected to main heating.

[0025] By suppressing variations in the amount of solvent in the thin film subjected to the main heating, a thin film with high film quality can be stably produced.

[0026] The heating device may further include a second chamber outside the first chamber that houses the main heating unit, and the transfer unit may transfer the substrate from the first chamber to the second chamber.

[0027] According to the above configuration, the main heating is performed in a second chamber different from the first chamber where the preheating is performed. By performing the main heating in a second chamber different from the first chamber, the atmosphere in the second chamber is less likely to affect the atmosphere in the first chamber, and the temperature and other conditions in the first chamber tend to be stable. This stabilizes the amount of solvent evaporated during the preheating, thereby suppressing variations in the state of the thin film subjected to the main heating.

[0028] The heating device may further include a connecting region that connects the first chamber and the second chamber in a closed manner, and the transfer unit may transfer the substrate from the first chamber to the second chamber via the connecting region.

[0029] The first chamber and the second chamber are connected in a closed manner, so that when the transfer unit transfers the substrate toward the second chamber, contact between the thin film and the air present in the space outside the first chamber and the second chamber can be suppressed. This configuration is preferable because it makes it easier to produce a high-quality thin film by suppressing deterioration of the thin film due to contact with air.

[0030] The heating method according to the present invention is a heating method for heating a substrate having a thin film formed on its surface, and includes the steps of: (a) preheating the substrate in a chamber to evaporate residual components of the thin film; (b) exhausting the atmospheric gas in the chamber from an exhaust port during or after the step (a); and (c) performing main heating in a short time of less than one second on the region on the substrate that has been preheated in the step (a).

[0031] Here, the term "residual component" refers to the solvent remaining in the thin film when the thin film is formed by a solution process or the like.

[0032] As described above, it is preferable to perform preheating on the thin film before performing the main heating. Furthermore, by evacuating the chamber during or after the preheating, the accumulation of vapors such as solvents in the chamber is suppressed. This stabilizes the amount of solvent evaporated during the preheating, thereby suppressing variations in the amount of solvent in the thin film to be subjected to the main heating.

[0033] In the above heating method, the step (c) is performed in a second space in the chamber that is substantially separated from a first space in which the preheating in the step (a) is performed via a partition wall, and the step (b) may include exhausting the ambient gas in the first space from the exhaust port.

[0034] Furthermore, the step (c) may be performed using a light source that emits light with a pulse width of less than 1 second.

[0035] In the above heating method, the thin film may be a perovskite film.

[0036] The step (a) may be performed by raising the temperature of the substrate to a range of 30°C to 150°C.

[0037] The conditions for performing preheating can be adjusted as appropriate depending on the structure of the thin film. For example, for a perovskite film, the temperature rise range during preheating is preferably set as described above, taking into account deterioration due to thermal decomposition of the material.

[0038] The substrate may be a substrate, a film, or paper.

[0039] As an example, the substrate is primarily made of one material selected from the group consisting of semiconductor, glass, metal, and resin. Usable substrates include semiconductor substrates, glass substrates, metal substrates, and resin substrates. Usable films include resin-based films, for example. Usable paper includes synthetic paper primarily made of resin, as well as high-quality paper and medium-quality paper. The term "primary material" used here refers to the material with the highest proportion of the materials constituting the substrate.

[0040] According to the present invention, a heating apparatus and a heating method are provided that can stably produce a high-quality thin film.

[0041] 4A is a diagram showing a schematic structure of a first embodiment of the heating device; FIG. 4B is a diagram showing a state in which a substrate has been transferred by a transfer unit from the state shown in FIG. 1A; FIG. 4C is a cross-sectional view of FIG. 1A; FIG. 4D is a flow chart showing a schematic example of an execution procedure of a heating method; FIG. 4E is a diagram showing a schematic structure of a second embodiment of the heating device; FIG. 4F is a cross-sectional view of FIG. 4A; FIG. 4G is a diagram showing another example of the configuration of the heating unit; FIG. 4H is a diagram showing another example of the configuration of the heating device; FIG. 4I is a diagram showing yet another example of the configuration of the heating device.

[0042] Configuration examples of the heating device according to the present invention will be described with reference to the drawings as appropriate. Note that the following drawings are all schematic illustrations, and the actual dimensional ratios do not necessarily match the dimensional ratios shown in the drawings. Furthermore, the dimensional ratios do not necessarily match between the drawings.

[0043] 1A is a diagram schematically illustrating the structure of a first embodiment of a heating device 1. As shown in FIG. 1A, the heating device 1 includes a chamber 2 a, a transfer unit 3 that transfers a substrate W1 to be treated within the chamber 2 a, a heater 5, and a flash lamp 7.

[0044] In the following drawings, the description will be made with reference to an X-Y-Z coordinate system, in which the direction perpendicular to the main surface of the substrate W1 is defined as the Z direction and the plane perpendicular to the Z direction is defined as the XY plane. The Z direction is typically the vertical direction.

[0045] In the following description, when a direction needs to be distinguished between positive and negative directions, it is described with a positive or negative sign, such as "+X direction" and "-X direction." When a direction is described without distinguishing between positive and negative directions, it is simply described as "X direction." In other words, in this specification, when simply referring to "X direction," it includes both "+X direction" and "-X direction." The same applies to the Y direction and the Z direction.

[0046] The heating device 1 is suitably used for heating a substrate W1 having a thin film W2 formed on its surface.

[0047] 1A, the substrate W1 is made of, for example, a glass substrate, and a thin film W2 is formed on the surface thereof. The thin film W2 is a perovskite film formed by a solution process such as spin coating.

[0048] For example, the thickness of the base material W1 in the Z direction is 10 μm to 5 mm. The film thickness of the thin film W2 is approximately 1 nm to 10 μm. Specific configuration examples of the base material W1 and the thin film W2 will be described later.

[0049] The configuration of the heating device 1 will be described below, followed by a heating method that can be performed by the heating device 1.

[0050] [Chamber 2a] As shown in Fig. 1A, the chamber 2a accommodates a heater 5 and a flash lamp 7. In the internal space of the chamber 2a, the substrate W1 is transferred by the transfer unit 3. Fig. 1B is a diagram showing a state in which the substrate W1 has been transferred by the transfer unit 3 from the state shown in Fig. 1A. In this embodiment, the substrate W1 is transferred in the X direction as shown in Figs. 1A and 1B.

[0051] 1A, the chamber 2a has a partition wall 10. The partition wall 10 is disposed in the internal space of the chamber 2a and serves to separate the chamber 2a into a first space R1 in which the heater 5 is disposed and a second space R2 in which the flash lamp 7 is disposed.

[0052] 1C is a cross-sectional view taken along the line CC in FIG. 1A. Note that, in FIG. 1C, the substrate W1 is illustrated for ease of understanding. As shown in FIG. 1C, the partition wall 10 has an opening 11 through which the substrate W1 transferred by the transfer unit 3 can pass. The opening 11 is a narrow path with a separation distance D1 of 20 mm or less from the transfer unit 3 on the +Z side. In other words, although the first space R1 and the second space R2 are connected through the opening 11, the communication area is extremely narrow, and therefore, it can be said that the partition wall 10 essentially divides the internal space of the chamber 2a into the first space R1 and the second space R2.

[0053] Just to be clear, the opening 11 is configured so that both the separation distance D2 from the transfer unit 3 on the -Z side and the separation distance D3 from the transfer unit 3 in the Y direction are smaller than the separation distance D1. In other words, "substantially partitioning" may refer to a state in which the separation distances D1 to D3 are all 20 mm or less.

[0054] 1A , the chamber 2a has an exhaust port 12 for exhausting the atmospheric gas G1 from the first space R1, for example, on a wall surface 20a on the +Z side. The exhaust port 12 is connected to a pipe 14 in which an intake mechanism 13, such as a fan, is disposed, and exhausts the atmospheric gas G1. The position of the exhaust port 12 is arbitrary as long as it exhausts the atmospheric gas G1 from the first space R1.

[0055] Furthermore, the chamber 2a has an inlet 15, for example, on the wall surface 20b on the -X side, through which a predetermined gas G2 can be introduced into the first space R1. The inlet 15 is provided from the perspective of introducing the gas G2 into the first space R1 in order to efficiently guide the atmospheric gas G1 to the exhaust port 12. The inlet 15 is connected to a gas introduction mechanism (not shown) via a pipe 16. For example, an inert gas such as nitrogen or clean dry air can be used as the gas G2.

[0056] Furthermore, the chamber 2a has an inlet 17 on the wall surface 20b for loading the substrate W1 into the first space R1, and an outlet 18 on the wall surface 20c on the +X side for unloading the substrate W1 from the second space R2. The inlet 17 has a narrow path similar to the opening 11, from the viewpoint of facilitating stabilization of the temperature and the like in the first space R1. The outlet 18 also has a narrow path similar to the opening 11, from the viewpoint of facilitating stabilization of the temperature and the like in the second space R2.

[0057] The entrance 17 and the exit 18 may be provided with an opening / closing mechanism (not shown) and may be opened only when the substrate W1 passes through.

[0058] Chamber 2a corresponds to the "first chamber."

[0059] [Transfer unit 3] The transfer unit 3 is configured by, for example, a conveyor. The transfer unit 3 carries the substrate W1 into the first space R1 through the carry-in entrance 17. Fig. 1A shows a state in which the substrate W1 is positioned in the first space R1.

[0060] The transfer unit 3 also transfers the substrate W1 to the second space R2 through the opening 11. Fig. 1B shows a state in which the substrate W1 is positioned in the second space R2. The transfer unit 3 then unloads the substrate W1 from the second space R2 through the unloading port 18.

[0061] [Heater 5] The heater 5 is disposed in the first space R1 as shown in Fig. 1A. The heater 5 is composed of an electric heating wire that radiates heat H1 when power is applied, and forms a heating area A1 in the first space R1. The heater 5 corresponds to the "preheating unit." The heating area A1 corresponds to the "first area."

[0062] 1A, for convenience of illustration, one heater 5 is shown, but a plurality of heaters 5 may be arranged in the first space R1. In addition, in FIG. 1A, the heater 5 is arranged on the +Z side of the substrate W1, but the installation position of the heater 5 is arbitrary as long as it can heat the substrate W1.

[0063] 1A illustrates a heater 5 as an example of the preheating unit, but the preheating unit may be configured with a light source such as a halogen lamp or an LED. In this case, light for heating (hereinafter referred to as "heating light") is irradiated from the light source toward the substrate W1 to form a heated region A1.

[0064] The substrate W1 is placed in the heating area A1 by the transport unit 3, whereby the substrate W1 is heated and preheating is performed on the substrate W1. During the preheating, the substrate W1 may be in a stationary state or in a transported state.

[0065] 1B, the flash lamp 7 is disposed in the second space R2. When the flash lamp 7 is turned on by a lighting circuit (not shown), it emits a flash of light L1 toward the substrate W1 to form a heated area A2. As a result, the flash of light L1 is irradiated onto the area on the substrate W1 that has been preheated, and main heating is performed.

[0066] Specifically, the flash lamp 7 is, for example, a xenon flash lamp that emits light with a pulse width of less than one second. The pulse width is preferably 100 milliseconds or less, and more preferably 10 milliseconds or less.

[0067] The flash lamp 7 corresponds to the "main heating unit." The heating area A2 corresponds to the "second area."

[0068] After the substrate W1 is placed in the heating region A2 by the transfer unit 3, a flash of light L1 emitted by a flash lamp 7 is irradiated onto the substrate W1, thereby performing main heating of the substrate W1. Fig. 1B schematically illustrates the flash of light L1 irradiated onto the substrate W1. During the main heating, the substrate W1 may be stationary or may be in a state of being transferred.

[0069] In this embodiment, the heating device 1 has a light-transmitting window 8. This light-transmitting window 8 is located on the -Z side of the flash lamp 7 and transmits the flash L1. Irradiation with the flash L1 may cause the material that makes up the thin film W2 to sublimate and scatter as gas, even if only slightly. Even in such a case, the provision of the light-transmitting window 8 prevents the tube of the flash lamp 7 from being soiled by the scattered material, etc.

[0070] If dirt occurs on the tubular surface of the flash lamp 7, the dirt will absorb the flash L1 when the flash lamp 7 is turned on, causing localized heating of the area where the dirt is present. Localized heating of the tubular body makes the tubular body more susceptible to malfunction. In view of the above, it is preferable to place a light-transmitting window 8 between the substrate W1 and the flash lamp 7, as shown in FIG. 1B, to prevent dirt from forming on the tubular body of the flash lamp 7.

[0071] [Heating Method] Next, a heating method that can be performed by the heating device 1 will be described.

[0072] 2 is a flow diagram showing an example of the procedure for carrying out the heating method M1. As shown in FIG. 2, the heating method M1 includes a substrate preparation step S1, a thin film formation step S2, a preheating step S3, an exhaust step S4, a main heating step S5, and a post-process S6.

[0073] [Substrate Preparation Step S1] First, a substrate W1 is prepared. The substrate W1 may be a substrate primarily made of a semiconductor such as silicon, glass such as quartz glass, metal such as copper or steel, or resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). The substrate W1 may also be, for example, a sheet-like resin film primarily made of resin. Furthermore, the substrate W1 may be synthetic paper primarily made of resin, or may be high-quality paper or medium-quality paper. The term "main material" refers to the material with the highest proportion of the materials constituting the substrate W1.

[0074] The base material W1 may have a film different from the thin film W2, such as a conductive layer made of a transparent conductive film such as ITO. In other words, in the thin film forming step S2 described later, the thin film W2 may be formed on the surface of the base material W1 via the above-mentioned film.

[0075] [Thin Film Forming Step S2] Next, a thin film W2 is formed on the surface of the substrate W1 by a solution process such as spin coating, a dropping method, or an inkjet method.

[0076] As an example, the thin film W2 is a perovskite film composed of an organometallic halide compound such as CH3NH3PbI3. The material constituting the thin film W2 is not limited to the organometallic halide compound; any material exhibiting a perovskite structure represented by the structural formula ABX3 can be used. For example, A is a carbon-containing organic group or an inorganic element, and at least one of CH3NH3, CH(NH2)2, Cs, and Rb is selected. Furthermore, B is a metal element, and at least one of Pb, Sn, Bi, and Sb is selected. Furthermore, X is a halogen element, and at least one of iodine, chlorine, and bromine is selected.

[0077] A solution containing the above materials can be prepared using a solvent such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or N-methyl-2-pyrrolidone (NMP). The solution is applied to the substrate W1 by solution processing to form a perovskite film.

[0078] The thin film W2 may also be formed by applying a metal nanoink in which metal nanoparticles such as gold or silver are dispersed by a solution process. Examples of the solvent in which the metal nanoparticles are dispersed include water and diethylene glycol butyl ether.

[0079] [Preheating step S3] Next, the substrate W1 on which the thin film W2 has been formed is transferred into the first space R1, and preheating is performed on the substrate W1 (see FIG. 1A ). The preheating is performed for the purpose of evaporating the solvent contained in the thin film W2.

[0080] When the thin film W2 is a perovskite film, the preheating is performed by raising the temperature of the substrate W1 to a range of 30°C to 150°C. From the viewpoint of suppressing deterioration of the perovskite film due to heating of the substrate W1, the temperature of the substrate W1 during preheating is preferably 150°C or lower, more preferably 130°C or lower, and particularly preferably 110°C or lower. Furthermore, from the viewpoint of efficiently evaporating the solvent in the thin film W2, the temperature of the substrate W1 during preheating is preferably 40°C or higher, more preferably 50°C or higher, and particularly preferably 60°C or higher. As an example, the temperature of the substrate W1 during preheating is set to 70°C.

[0081] Furthermore, when the thin film W2 is formed of metal nano-ink, the preheating is performed by raising the temperature of the substrate W1 to a range of 50°C to 150°C.

[0082] The temperature of the substrate W1 during preheating can be measured, for example, by attaching a thermocouple to the substrate W1. A K-type thermocouple can be used as the thermocouple. For example, a test substrate W1 to which a thermocouple is attached may be prepared, and the heating conditions for the substrate W1 in the preheating step S3 may be set based on the temperature of the substrate W1.

[0083] The preheating time is arbitrary, but is, for example, one minute, which is longer than the main heating time described below. Note that the preheating time may refer to the time during which the temperature of the substrate W1 is maintained at or above a predetermined temperature.

[0084] The preheating step S3 corresponds to the step (a).

[0085] [Exhaust Step S4] After the preheating step S3 is performed, the atmospheric gas G1 in the first space R1 is exhausted through the exhaust port 12. The exhausted gas containing the atmospheric gas G1 contains vapor derived from the solvent used in the thin film forming step S2, and therefore is preferably recovered in a duct (not shown) having an optional filter.

[0086] By performing the preheating step S3, the solvent in the thin film W2 is evaporated. If the exhausting step S4 is not performed, the preheating step S3 is repeated in the first space R1, which increases the concentration of solvent vapor in the first space R1. If the concentration of the vapor in the first space R1 increases, the solvent becomes less likely to evaporate from the thin film W2 during the preheating step S3. This causes the amount of solvent evaporated in the preheating step S3 to vary, resulting in variations in the amount of solvent contained in the thin film W2 subjected to the subsequent main heating step S5.

[0087] 2, after the preheating step S3 is performed, it is preferable to evacuate the first space R1 through the exhaust port 12. Note that the evacuation step S4 may be performed during the preheating step S3.

[0088] It may also appear that the atmospheric gas G1 flows out of the first space R1, for example, through the inlet 17 or the opening 11. Here, the inlet 17 and the opening 11 are narrow paths as described above. Therefore, it can be said that the movement of gas through the inlet 17 or the opening 11 is extremely small. In other words, from the viewpoint of preventing the accumulation of solvent vapor in the first space R1, exhausting the atmospheric gas G1 through the inlet 17 and the opening 11 is insufficient.

[0089] The exhaust step S4 corresponds to the step (b).

[0090] [Main Heating Step S5] Next, as shown in FIG. 1B, the base material W1 is transferred to the second space R2, and the main heating is performed on the base material W1.

[0091] 1B, the main heating is performed by turning on the flash lamps 7 while the substrate W1 is placed in the heating region A2. Therefore, the main heating is performed for a short time of less than 1 second. The main heating step S5 is performed for the purpose of heating the thin film W2 for a short time with a high energy density.

[0092] When the thin film W2 is a perovskite film, the crystal size of the thin film W2 increases when the thin film W2 is heated to a high temperature for a short time of less than one second. In addition, the instantaneous heating suppresses deterioration of the thin film W2 due to heating to a high temperature and the thermal influence on the base material W1.

[0093] Because the thin film W2 instantaneously reaches a high temperature, if a large amount of solvent remains in the thin film W2, the solvent may bump, causing pinholes or the like to form in the thin film W2, thereby degrading the film quality of the thin film W2. However, as shown in Figure 2, by performing the pre-heating step S3 before performing the main heating step S5, the amount of solvent remaining in the thin film W2 of the substrate W1 to be subjected to the main heating is reduced, and degradation of the film quality of the thin film W2 during the main heating is suppressed.

[0094] Although not shown in the drawings, the pre-heating step S3 may be performed on a substrate different from the substrate W1 while the main heating step S5 is being performed on the substrate W1.

[0095] Furthermore, even when the thin film W2 is a coating film of metal nanoink, the preheating step S3 and the evacuation step S4 are performed before the main heating step S5.

[0096] More specifically, the thin film W2 made of metal nanoink is sintered more firmly by the heating step S5. However, if a large amount of the solvent in which the metal nanoparticles were dispersed is present in the thin film W2, the quality of the sintered thin film W2 is likely to deteriorate due to bumping of the solvent. In contrast, by performing the pre-heating step S3 before performing the heating step S5, the amount of solvent in the thin film W2 can be reduced, and deterioration of the quality of the thin film W2 during the heating step S5 can be suppressed.

[0097] Furthermore, from the viewpoint of stabilizing the state of the thin film W2 to be subjected to the main heating step S5, the point of performing the evacuation step S4 can be discussed in the same manner as the above discussion regarding the perovskite film.

[0098] This heating step S5 corresponds to step (c).

[0099] [Post-Process S6] Thereafter, the substrate W1 is carried out from the chamber 2a, and a film different from the thin film W2, an electrode film for applying a voltage to the thin film W2, or the like is formed on the thin film W2 as appropriate.

[0100] Second Embodiment A second embodiment of the heating device will be described below with reference to the drawings, focusing on differences from the first embodiment. Fig. 3 is a diagram schematically illustrating the structure of the second embodiment of the heating device.

[0101] This embodiment differs from the first embodiment in that the heating device 1a includes a chamber 2b, and the transfer unit 3 transfers the substrate W1 from the chamber 2a to the chamber 2b. In this embodiment, the chamber 2a corresponds to the "first chamber," and the chamber 2b corresponds to the "second chamber."

[0102] As shown in Fig. 3, the chamber 2a forms a first space R1 that houses the heater 5. As shown in Fig. 3, the chamber 2b forms a second space R2 that houses the flash lamp 7. Fig. 3 illustrates a state in which the substrate W1 is positioned in the chamber 2b, similar to Fig. 1B.

[0103] The heater 5 forms a heating area A1 in the first space R1, and the flash lamp 7 forms a heating area A2 in the second space R2, as described with reference to FIGS. 1A and 1B.

[0104] 1B, the flash lamp 7 irradiates the substrate W1 with a flash of light L1 through a light-transmitting window 8 disposed in the chamber 2b. As a result, the flash of light L1 is irradiated onto the region on the substrate W1 that has been preheated, and main heating is performed.

[0105] The chamber 2b also has a loading port 27 on the wall surface 21b on the -X side for loading the substrate W1 into the second space R2, and a loading port 28 on the wall surface 21c on the +X side for unloading the substrate W1.

[0106] The transfer unit 3 unloads the substrate W1 from the unloading port 18 of the chamber 2a, and then transfers the substrate W1 into the chamber 2b through the load port 27 of the chamber 2b. Then, after the main heating of the substrate W1 is performed, the transfer unit 3 unloads the substrate W1 from the chamber 2b through the unloading port 28.

[0107] 3, the heating device 1a is configured with a chamber 2a, which houses a heater 5 and performs preheating, and a chamber 2b, which houses a flash lamp 7 and performs main heating, as separate chambers. This makes it less likely that the atmosphere in chamber 2b will affect the atmosphere in chamber 2a, making it easier to stabilize the temperature and other conditions in chamber 2a. If the temperature and other conditions in chamber 2a are stable, the amount of solvent evaporated during preheating will be more stable, and variations in the amount of solvent in the thin film W2 to be subjected to main heating will be reduced.

[0108] 4A is a diagram showing a modified example of the heating device 1a according to the second embodiment. As shown in FIG. 4A, the heating device 1a may have a cylindrical portion 30 that connects the chamber 2a and the chamber 2b.

[0109] Fig. 4B is a cross-sectional view taken along line BB of Fig. 4A. As shown in Fig. 4B, the cylindrical portion 30 is configured to cover the periphery of the transfer unit 3. In other words, the cylindrical portion 30 connects the chamber 2a and the chamber 2b in a closed manner.

[0110] The cylindrical portion 30 connects the chambers 2a and 2b in a closed manner, thereby preventing the thin film W2 from coming into contact with the air G3 present in the space outside the chambers 2a and 2b when the transfer unit 3 transfers the substrate W1 toward the chamber 2b. For example, the chambers 2a and 2b may be connected in a closed manner from the viewpoint of preventing deterioration of the thin film W2 due to contact between the oxygen in the air G3 and the thin film W2.

[0111] Another embodiment of the heating device 1 will now be described.

[0112] <1> In the above description, the heating unit has been described as being configured using flash lamps 7. However, the configuration of the heating unit is arbitrary as long as it can heat the thin film W2 instantaneously, i.e., in a short time of less than one second. Figure 5 is a diagram showing another example of the configuration of the heating unit. In Figure 5, the configuration on the -X side of the chamber 2a is omitted.

[0113] 5, this heating unit is composed of, for example, a halogen lamp 9a and a slide mechanism 9b that can move the halogen lamp 9a in the X direction. The slide mechanism 9b moves the halogen lamp 9a at high speed from the +X side of the substrate W1 to the -X side of the substrate W1 while the halogen lamp 9a is emitting heating light L2 toward the -Z side. This allows the substrate W1 to be instantaneously irradiated with heating light L2, thereby heating the thin film W2 in a short time of less than one second.

[0114] 5, the light source of the heating light L2 is described as being a halogen lamp, but the light source may have any configuration. For example, the light source may be a high-pressure mercury lamp, an LED, or a laser light source.

[0115] The sliding mechanism 9b may move the light source within the XY plane depending on the irradiation range of the heating light L2 from the light source. Furthermore, the sliding mechanism 9b may move multiple times relative to the substrate W1 while changing the irradiation range of the heating light L2 on the substrate W1.

[0116] <2> In the above description, the light-transmitting window 8 is disposed on the −Z side of the flash lamp 7. However, whether or not the light-transmitting window 8 is disposed can be appropriately selected in consideration of the configuration of the heating unit and the distance between the flash lamp 7 and the substrate W1. In other words, whether or not the light-transmitting window 8 is disposed in the heating device (1, 1a) is optional.

[0117] <3> Fig. 6 is a diagram showing another example of the configuration of the heating device 1, following Fig. 1A etc. Fig. 6 shows a scene in which preheating is being performed on the substrate W1.

[0118] In the above description, the heater 5 is disposed in the first space R1 and the flash lamp 7 is disposed in the second space R2, i.e., the heater 5 and the flash lamp 7 are disposed in different spaces, as shown in Figures 1A and 1B. However, as shown in Figure 6, the heater 5 and the flash lamp 7 may be disposed in the same space within the chamber 2a. In this case, the preheating step S3 and the main heating step S5 are performed in the same space. In other words, whether or not the chamber 2a includes a partition wall 10 is optional, as shown in Figure 1A and other figures.

[0119] <4> Fig. 7 is a diagram showing yet another example of the configuration of the heating device 1, following Fig. 1A etc. As shown in Fig. 7, the transfer unit 3 may be composed of a plurality of rollers 3a, and the substrate W1 may be transferred by rotation of these rollers 3a. For example, when the substrate W1 is composed of a film-like sheet, the substrate W1 is preferably transferred by the rollers 3a.

[0120] Although FIG. 7 is based on the heating device 1 according to FIGS. 1A and 1B, the substrate W1 may be transported by rollers 3a in the heating device 1a according to FIG. 3 or 4A, for example.

[0121] <5> The configuration of the transfer unit 3 is arbitrary as long as it can transfer the substrate W1 from the heating region A1 to the heating region A2. For example, the transfer unit 3 may be configured to include a transport mechanism such as a robot arm.

[0122] <6> The preheating unit may be a heat stage that comes into contact with the −Z side surface of the substrate W1. In this case, the transfer unit 3 preferably includes a transport mechanism such as a robot arm that transfers the substrate W1.

[0123] <7> The heating of a perovskite film and a metal nanoink coating film has been described above. However, the present invention is not limited to the above and can also be suitably used for heating in forming, for example, films constituting an electron transport layer or a hole transport layer in a solar cell, a ferroelectric film, or a carbon ink coating film.

[0124] <8> The above describes the pre-heating step S3, the exhaust step S4, and the main heating step S5 performed in the heating device (1, 1a). The present invention does not exclude a configuration in which, for example, a chamber or the like performing the thin film forming step S2 is incorporated before the heating device (1, 1a), or a configuration in which a chamber or the like performing the post-process S6 is incorporated after the heating device (1, 1a).

[0125] <9> The embodiments of the heating device and the heating method are not limited to the above examples. Furthermore, the configurations according to the above embodiments can be realized by combining them as appropriate.

[0126] 1, 1a: Heating device 2a, 2b: Chamber 3: Transfer unit 3a: Roller 5: Heater 7: Flash lamp 8: Light-transmitting window 9a: Halogen lamp 9b: Slide mechanism 10: Partition wall 11: Opening 12: Exhaust port 13: Intake mechanism 14: Pipe 15: Inlet 16: Pipe 17, 27: Carry-in entrance 18, 28: Carry-out exit 20a, 20b, 20c: Wall surface 21b, 21c: Wall surface 30: Cylinder

Claims

1. A heating device for heating a substrate having a thin film formed on its surface, comprising: a main heating unit capable of short-time heating of less than one second; a pre-heating unit having a heating mechanism capable of longer-time heating than the main heating unit; a transfer unit for transferring the substrate from a first region heated by the pre-heating unit to a second region heated by the main heating unit; a first chamber that houses at least the pre-heating unit; and an exhaust port for exhausting atmospheric gas within the first chamber.

2. The heating device according to claim 1, wherein the first chamber contains both the preheating unit and the main heating unit, and has a partition wall which essentially separates a first space in which the preheating unit is disposed and in which the first region is located, from a second space in which the main heating unit is disposed and in which the second region is located, while ensuring a transport space for the substrate, and the exhaust port exhausts atmospheric gas from the first space.

3. The heating device according to claim 1, further comprising a second chamber outside the first chamber for accommodating the main heating unit, and the transfer unit transfers the substrate from the first chamber to the second chamber.

4. The heating device according to claim 3, further comprising a connecting region that connects the first chamber and the second chamber in a closed manner, and the transfer unit transfers the substrate from the first chamber to the second chamber via the connecting region.

5. A heating device according to any one of claims 1 to 4, characterized in that the heating unit includes a light source that emits light with a pulse width of less than one second.

6. A heating method for heating a substrate having a thin film formed on its surface, comprising: a step (a) of preheating the substrate in a chamber to evaporate residual components of the thin film; a step (b) of exhausting the atmospheric gas in the chamber from an exhaust port during or after the step (a); and a step (c) of performing main heating in a short period of less than one second on the region on the substrate that has been preheated in the step (a).

7. The heating method according to claim 6, wherein the step (c) is performed in a second space within the chamber that is substantially separated from a first space in which the preheating by the step (a) is performed via a partition wall, and the step (b) exhausts the atmospheric gas in the first space from the exhaust port.

8. The heating method according to claim 6 or 7, characterized in that step (c) is carried out using a light source that emits light with a pulse width of less than 1 second.

9. The heating method according to claim 6 or 7, wherein the thin film is a perovskite film.

10. The heating method according to claim 9, wherein the step (a) comprises raising the temperature of the substrate to a range of 30°C to 150°C.

11. The heating method according to claim 10, wherein the base material is a substrate, a film, or paper.

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