Title of Invention: METHOD AND DEVICE FOR MANUFACTURING FLEXIBLE LIGHT EMISSION DEVICE Abstract: According to a flexible light-emitting device production method of the present disclosure, after an intermediate region (30i) and flexible substrate regions (30d) of a plastic film (30) of a multilayer stack (100) are divided from one another, the interface between the flexible substrate regions (30d) and a glass base (10) is irradiated with lift-off light. The multilayer stack (100) is separated into a first portion (110) and a second portion (120) while the multilayer stack (100) is in contact with a stage (210). The first portion (110) includes a plurality of light-emitting devices (1000) which are in contact with the stage (210). The light-emitting devices (1000) include a plurality of functional layer regions (20) and the flexible substrate regions (30d). The second portion (120) includes the glass base (10) and the intermediate region (30i). The step of irradiating with the lift-off light includes the first light scanning for scanning the interface in a first direction with the light in the form of a line beam, and the second light scanning for scanning the interface in a second direction with the light. In each of the first and second light scanning, the irradiation intensity is modulated such that the intensity for at least part of the interface between the intermediate region (30i) and the glass base (10) is lower than the irradiation intensity for the interface between the flexible substrate regions (30d) and the glass base (10). Detailed Description: TECHNICAL FIELD The present disclosure relates to a method and apparatus for producing a flexible light-emitting device. BACKGROUND ART A typical example of the flexible display includes a film which is made of a synthetic resin such as polyimide (hereinafter, referred to as “plastic film”), and elements supported by the plastic film, such as TFTs (Thin Film Transistors) and OLEDs (Organic Light Emitting Diodes). The plastic film functions as a flexible substrate. The flexible display is encapsulated with a gas barrier film (encapsulation film) because an organic semiconductor layer which is a constituent of the OLED is likely to deteriorate due to water vapor. Production of the above-described flexible display is carried out using a glass base on which a plastic film is formed over the upper surface. The glass base functions as a support (carrier) for keeping the shape of the plastic film flat during the production process. TFT devices, light-emitting devices such as OLEDs, a gas barrier film, and the other constituents are formed on the plastic film, whereby the structure of a flexible display is realized while it is supported by the glass base. Thereafter, the flexible display is delaminated from the glass base and gains flexibility. The entirety of a portion in which TFT devices and light-emitting devices such as OLEDs are arrayed can be referred to as “functional layer region”. According to the prior art, a sheet-like structure including a plurality of flexible displays is delaminated from a glass base, and thereafter, optical parts and other constituents are mounted to this sheet-like structure. Thereafter, the sheet-like structure is divided into a plurality of flexible devices. This dividing is realized by, for example, laser beam irradiation. Patent Document No. 1 discloses the method of irradiating the interface between each flexible display and the glass base with laser light in order to delaminate each flexible display from the glass base (supporting substrate). According to the method disclosed in Patent Document No. 1, after irradiation with the lift-off light, respective flexible displays are divided from one another, and each of the flexible displays is delaminated from the glass base. CITATION LIST Patent Literature Patent Document No. 1: Japanese Laid-Open Patent Publication No. 2014-48619 SUMMARY OF INVENTION Technical Problem According to the conventional production method, the dividing by means of laser beam irradiation is carried out after expensive parts, for example, encapsulation film, polarizer, and/or heat radiation sheet, are mounted to a sheet-like structure including a plurality of flexible displays. Therefore, unnecessary portions divided by laser beam irradiation, i.e., portions which are not to be constituents of a final display, are quite useless. Also, there is a problem that, after being delaminated from the glass base, it is difficult to handle a plurality of flexible displays which have no rigidity. Such a problem is not limited to flexible displays which include OLEDs as light-emitting devices but can arise in producing a flexible light-emitting device which includes a micro LED (PLED) formed as a light-emitting device using inorganic semiconductor materials. The present disclosure provides a method and apparatus for producing a flexible light-emitting device which are capable of solving the above-described problems. Solution to Problem A flexible light-emitting device production method of the present disclosure includes, in an exemplary embodiment, providing a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and a light-emitting device layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface, dividing the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film from one another, irradiating an interface between the synthetic resin film and the glass base with lift-off light, and separating the multilayer stack into a first portion and a second portion by increasing a distance from a stage to the glass base while the second surface of the multilayer stack is kept in contact with the stage, wherein the first portion of the multilayer stack includes a plurality of light-emitting devices which are in contact with the stage, and the plurality of light-emitting devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film, irradiating the interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base with the lift-off light includes first light scanning for scanning the interface in a first direction parallel to the interface with the lift-off light in the form of a line beam which is transverse to the first direction, and second light scanning for scanning the interface in a second direction which is parallel to the interface and different from the first direction with the lift-off light in the form of a line beam which is transverse to the second direction, and in each of the first and second light scanning, an irradiation intensity of the lift-off light is modulated such that an irradiation intensity of the lift-off light for at least part of an interface between the intermediate region of the synthetic resin film and the glass base is lower than an irradiation intensity of the lift-off light for the interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base. In one embodiment, the lift-off light is incoherent light. In one embodiment, the light-emitting device layer includes a plurality of arrayed micro LEDs, and the lift-off light is laser light. In one embodiment, in each of the first and second light scanning, an irradiation intensity of the lift-off light is lower than a threshold level which is necessary for delaminating the plurality of flexible substrate regions of the synthetic resin film from the glass base through a single scanning cycle, and a sum of irradiation intensities of the lift-off light in the first and second light scanning is higher than the threshold level. In one embodiment, providing the multilayer stack includes providing a delamination layer between the glass base and the synthetic resin film. In one embodiment, the delamination layer is made of a metal or a semiconductor. In one embodiment, the lift-off light is a line beam extending in a direction parallel to a peripheral edge of the glass base, and irradiating the interface between the synthetic resin film and the glass base with the lift-off light includes moving an irradiation region on the interface which is to be irradiated with the lift-off light in another direction which is transverse to an extending direction of the line beam. In one embodiment, the at least part of the interface between the intermediate region of the synthetic resin film and the glass base includes two parallel stripe regions extending along the peripheral edge of the glass base. In one embodiment, the at least part of the interface between the intermediate region of the synthetic resin film and the glass base includes at least one middle stripe region which is parallel to the stripe regions. In one embodiment, the at least part of the interface between the intermediate region of the synthetic resin film and the glass base has a width which is not less than 50% of a width of the intermediate region. In one embodiment, the at least part of the interface between the intermediate region of the synthetic resin film and the glass base has a width which is not less than 1 mm. In one embodiment, the method further includes, after separating the multilayer stack into the first portion and the second portion, sequentially or concurrently performing a process on the plurality of light-emitting devices which are in contact with the stage. In one embodiment, the process includes any of attaching a dielectric and/or electrically-conductive film to each of the plurality of light-emitting devices, cleaning or etching each of the plurality of light-emitting devices, and mounting an optical part and/or an electronic part to each of the plurality of light-emitting devices. A flexible light-emitting device production apparatus of the present disclosure includes, in an exemplary embodiment, a stage for supporting a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and a light-emitting device layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface, the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film being divided from one another, and a lift-off light irradiation unit for irradiating with lift-off light an interface between the synthetic resin film and the glass base in the multilayer stack supported by the stage, wherein the lift-off light irradiation unit includes first light scanning for scanning the interface in a first direction parallel to the interface with the lift-off light in the form of a line beam which is transverse to the first direction, and second light scanning for scanning the interface in a second direction which is parallel to the interface and different from the first direction with the lift-off light in the form of a line beam which is transverse to the second direction, and in each of the first and second light scanning, an irradiation intensity of the lift-off light is modulated such that an irradiation intensity of the lift-off light for at least part of an interface between the intermediate region of the synthetic resin film and the glass base is lower than an irradiation intensity of the lift-off light for the interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base. In one embodiment, the lift-off light irradiation unit comprises an incoherent light source. In one embodiment, the light-emitting device layer includes a plurality of arrayed micro LEDs, and the lift-off light irradiation unit comprises a laser light source. In one embodiment, in each of the first and second light scanning, an irradiation intensity of the lift-off light is lower than a threshold level which is necessary for delaminating the plurality of flexible substrate regions of the synthetic resin film from the glass base through a single scanning cycle, and a sum of irradiation intensities of the lift-off light in the first and second light scanning is higher than the threshold level. In one embodiment, the apparatus further includes an actuator for increasing a distance from the stage to the glass base while the stage is kept in contact with the second surface of the multilayer stack, thereby separating the multilayer stack into a first portion and a second portion, wherein the first portion of the multilayer stack includes a plurality of light-emitting devices which are in contact with the stage, and the plurality of light-emitting devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, and the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film. Advantageous Effects of Invention According to an embodiment of the present invention, a novel method for producing a flexible light-emitting device which is capable of solving the above-described problems is provided. BRIEF DESCRIPTION OF DRAWINGS FIG. 1A is a plan view showing a configuration example of a multilayer stack used in a flexible light-emitting device production method of the present disclosure. FIG. 1B is a cross-sectional view of the multilayer stack taken along line B-B of FIG. 1A. FIG. 1C is a cross-sectional view showing another example of the multilayer stack. FIG. 1D is a cross-sectional view showing still another example of the multilayer stack. FIG. 2 is a cross-sectional view schematically showing the dividing positions in the multilayer stack. FIG. 3A is a diagram schematically showing a state immediately before a stage supports a multilayer stack. FIG. 3B is a diagram schematically showing a state where the stage supports the multilayer stack. FIG. 3C is a diagram schematically showing that the interface between a glass base and a plastic film of the multilayer stack with lift-off light. FIG. 4A is a perspective view schematically showing irradiation of the multilayer stack with a line beam emitted from a line beam source of a delaminating apparatus. FIG. 4B is a perspective view schematically showing the position of the stage at the start of the first light scanning. FIG. 4C is a perspective view schematically showing the position of the stage at the end of the first light scanning. FIG. 4D is a perspective view schematically showing a multilayer stack with its orientation being rotated by 90° on an axis parallel to the Z-axis. FIG. 4E is a perspective view schematically showing the position of the stage at the end of the second light scanning. FIG. 5A is a perspective view schematically showing the first light scanning. FIG. 5B is a perspective view schematically showing the first light scanning. FIG. 5C is a perspective view schematically showing the first light scanning. FIG. 5D is a perspective view schematically showing the second light scanning. FIG. 6 is a diagram schematically showing an example of the distribution in the Y-axis direction of the irradiation intensity of the lift-off light in the first light scanning. FIG. 7 is a diagram schematically showing another example of the distribution in the Y-axis direction of the irradiation intensity of the lift-off light in the first light scanning. FIG. 8 is a diagram schematically showing an example of the distribution in the X-axis direction (scanning direction) of the irradiation intensity of the lift-off light in the first light scanning. FIG. 9 is a diagram schematically showing another example of the distribution in the X-axis direction of the irradiation intensity of the lift-off light in the first light scanning. FIG. 10A is a diagram schematically showing still another example of the distribution in the X-axis direction of the irradiation intensity of the lift-off light. FIG. 10B is a diagram schematically showing still another example of the distribution in the X-axis direction of the irradiation intensity of the lift-off light. FIG. 11 is a diagram schematically showing an example of the distribution in the Y-axis direction of the irradiation intensity of the lift-off light in the second light scanning. FIG. 12 is a diagram schematically showing another example of the distribution in the Y-axis direction of the irradiation intensity of the lift-off light in the second light scanning. FIG. 13 is a diagram schematically showing an example of the distribution in the X-axis direction (scanning direction) of the irradiation intensity of the lift-off light in the second light scanning. FIG. 14 is a diagram schematically showing another example of the distribution in the X-axis direction of the irradiation intensity of the lift-off light in the second light scanning. FIG. 15A is a plan view schematically showing low irradiation regions by the first light scanning. FIG. 15B is a plan view schematically showing low irradiation regions by the second light scanning. FIG. 15C is a plan view schematically showing the entire shape of a low irradiation region after the first and second light scanning. FIG. 16A is a cross-sectional view schematically showing the multilayer stack before the multilayer stack is separated into the first portion and the second portion after irradiation with lift-off light. FIG. 16B is a cross-sectional view schematically showing the multilayer stack separated into the first portion and the second portion. FIG. 17 is a perspective view showing the glass base separated from the multilayer stack by a delaminating apparatus. FIG. 18 is a perspective view showing removal of the glass base from the stage. FIG. 19 is a perspective view showing the stage from which the glass base has been removed. FIG. 20 is a cross-sectional view showing the stage from which the glass base has been removed. FIG. 21 is a cross-sectional view showing flexible light-emitting devices detached from the stage. FIG. 22 is a cross-sectional view showing another protection sheet bound to a plurality of light-emitting devices which are in contact with the stage. FIG. 23 is a cross-sectional view showing a carrier sheet carrying a plurality of parts which are to be mounted to the plurality of light-emitting devices. FIG. 24A is a cross-sectional view illustrating a step of the flexible light-emitting device production method in an embodiment of the present disclosure. FIG. 24B is a cross-sectional view illustrating a step of the flexible light-emitting device production method in an embodiment of the present disclosure. FIG. 24C is a cross-sectional view illustrating a step of the flexible light-emitting device production method in an embodiment of the present disclosure. FIG. 24D is a cross-sectional view illustrating a step of the flexible light-emitting device production method in an embodiment of the present disclosure. FIG. 25 is an equivalent circuit diagram of a single sub-pixel in a flexible light-emitting device. FIG. 26 is a perspective view of the multilayer stack in the middle of the production process. FIG. 27A is a diagram schematically showing the upper surface of a line beam source 214 which includes a single column of light emitting diode devices arrayed in Y-axis direction. FIG. 27B is a cross-sectional view of the line beam source shown in FIG. 27A taken along line B-B. FIG. 27C is a diagram showing the moving direction of the line beam source relative to the multilayer stack 100. FIG. 28A is a diagram schematically showing the upper surface of a line beam source 214 which includes a plurality of columns of light emitting diode devices arrayed in Y-axis direction. FIG. 28B is a cross-sectional view of the line beam source shown in FIG. 28A taken along line B-B. FIG. 28C is a diagram showing the moving direction of the line beam source relative to the multilayer stack. FIG. 28D is a plan view schematically showing irradiation regions the line beam source of FIG. 28A is forming. FIG. 28E is a plan view showing an example of irradiation regions formed by temporarily modulating the electric current flowing through each of the light emitting diode devices during scanning by the line beam source. DESCRIPTION OF EMBODIMENTS An embodiment of a method and apparatus for producing a flexible light-emitting device of the present disclosure is described with reference to the drawings. Examples of the “light-emitting device” include displays and illumination devices. In the following description, unnecessarily detailed description will be omitted. For example, detailed description of well-known matter and repetitive description of substantially identical elements will be omitted. This is for the purpose of avoiding the following description from being unnecessarily redundant and assisting those skilled in the art to easily understand the description. The present inventors provide the attached drawings and the following description for the purpose of assisting those skilled in the art to fully understand the present disclosure. Providing these drawings and description does not intend to limit the subject matter recited in the claims. <Multilayer Stack> See FIG. 1A and FIG. 1B. In a flexible light-emitting device production method of the present embodiment, firstly, a multilayer stack 100 illustrated in FIG. 1A and FIG. 1B is provided. FIG. 1A is a plan view of the multilayer stack 100. FIG. 1B is a cross-sectional view of the multilayer stack 100 taken along line B-B of FIG. 1A. In FIG. 1A and FIG. 1B, an XYZ coordinate system with X-axis, Y-axis and Z-axis, which are perpendicular to one another, is shown for reference. The multilayer stack 100 includes a glass base (motherboard or carrier) 10, a plurality of functional layer regions 20 each including a TFT layer 20A and a light-emitting device layer 20B, a synthetic resin film (hereinafter, simply referred to as “plastic film”) 30 provided between the glass base 10 and the plurality of functional layer regions 20 and bound to the glass base 10, and a protection sheet 50 covering the plurality of functional layer regions 20. The multilayer stack 100 further includes a gas barrier film 40 provided between the plurality of functional layer regions 20 and the protection sheet 50 so as to cover the entirety of the functional layer regions 20. The multilayer stack 100 may include another unshown layer, such as a buffer layer. In the present embodiment, the light-emitting device layer 20B includes, for example, a plurality of OLED devices which are two-dimensionally arrayed. In the present disclosure, the “light-emitting device layer” refers to a two-dimensional array of light-emitting devices. Each of the light-emitting devices is not limited to an OLED device but may be a micro LED device. In the present embodiment, a typical example of the flexible light-emitting device is a “flexible display” but may be a “flexible illumination device”. The first surface 100a of the multilayer stack 100 is defined by the glass base 10. The second surface 100b of the multilayer stack 100 is defined by the protection sheet 50. The glass base 10 and the protection sheet 50 are materials temporarily used in the production process but are not constituents of a final flexible light-emitting device. The plastic film 30 shown in the drawings includes a plurality of flexible substrate regions 30d respectively supporting the plurality of functional layer regions 20, and an intermediate region 30i surrounding each of the flexible substrate regions 30d. The flexible substrate regions 30d and the intermediate region 30i are merely different portions of a single continuous plastic film 30 and do not need to be physically distinguished. In other words, regions of the plastic film 30 lying immediately under respective ones of the functional layer regions 20 are the flexible substrate regions 30d, and the other region of the plastic film 30 is the intermediate region 30i. Each of the plurality of functional layer regions 20 is a constituent of a final flexible light-emitting device (e.g., display panel). In other words, the multilayer stack 100 has such a structure that a plurality of flexible light-emitting devices which are not yet divided from one another are supported by a single glass base 10. Each of the functional layer regions 20 has such a shape that, for example, the thickness (size in Z-axis direction) is several tens of micrometers, the length (size in X-axis direction) is about 12 cm, and the width (size in Y-axis direction) is about 7 cm. These sizes can be set to arbitrary values according to the required largeness of the display screen or emission surface region. The shape in the XY plane of each of the functional layer regions 20 is rectangular in the example illustrated in the drawings but is not limited to this example. The shape in the XY plane of each of the functional layer regions 20 may include a square, a polygon, or a shape which includes a curve in the contour. As shown in FIG. 1A, the flexible substrate regions 30d are two-dimensionally arrayed in rows and columns according to the arrangement of the flexible light-emitting devices. The intermediate region 30i consists of a plurality of stripes perpendicular to one another and forms a grid pattern. The width of the stripes is, for example, about 1-4 mm. The flexible substrate region 30d of the plastic film 30 functions as the “flexible substrate” in each flexible light-emitting device which is in the form of a final product. Meanwhile, the intermediate region 30i of the plastic film 30 is not a constituent of the final product. In an embodiment of the present disclosure, the configuration of the multilayer stack 100 is not limited to the example illustrated in the drawings. The number of functional layer regions 20 supported by a single glass base 10 is arbitrary. The size or proportion of each component illustrated in respective drawings is determined from the viewpoint of understandability. The actual size or proportion is not necessarily reflected in the drawings. The multilayer stack 100 which can be used in the production method of the present disclosure is not limited to the example illustrated in FIG. 1A and FIG. 1B. FIG. 1C and FIG. 1D are cross-sectional views showing other examples of the multilayer stack 100. In the example illustrated FIG. 1C, the protection sheet 50 covers the entirety of the plastic film 30 and extends outward beyond the plastic film 30. In the example illustrated FIG. 1D, the protection sheet covers the entirety of the plastic film 30 and extends outward beyond the glass base 10. As will be described later, after the glass base 10 is separated from the multilayer stack 100, the multilayer stack 100 is a thin flexible sheet-like structure which has no rigidity. The protection sheet 50 serves to protect the functional layer regions 20 from impact and abrasion when the functional layer regions 20 collide with or come into contact with external apparatuses or instruments in the step of delaminating the glass base 10 and the steps after the delaminating. Since the protection sheet 50 is peeled off from the multilayer stack 100 in the end, a typical example of the protection sheet 50 has a laminate structure which includes an adhesive layer of a relatively small adhesive force (a layer of an applied mold-releasing agent) over its surface. The more detailed description of the multilayer stack 100 will be described later. <Dividing of Light-Emitting Devices> According to the flexible light-emitting device production method of the present embodiment, after the step of providing the above-described multilayer stack 100, the step of dividing an intermediate region 30i and respective ones of a plurality of flexible substrate regions 30d of the plastic film 30 from one another is carried out. FIG. 2 is a cross-sectional view schematically showing the positions for dividing the intermediate region 30i and respective ones of the plurality of flexible substrate regions 30d of the plastic film 30 from one another. The positions of irradiation extend along the periphery of each of the flexible substrate regions 30d. In FIG. 2, the positions indicated by arrows are irradiated with a laser beam for cutting. Part of the multilayer stack 100 exclusive of the glass base 10 is cut into a plurality of light-emitting devices (e.g., display panels) 1000 and the remaining unnecessary portions. By cutting, a gap of several tens of micrometers to several hundreds of micrometers is formed between each of the light-emitting devices 1000 and a portion surrounding the light-emitting device 1000. The cutting can also be realized by a cutter which has a fixed blade or a rotary blade instead of the laser beam irradiation. After the cutting, the light-emitting devices 1000 and the remaining unnecessary portions are still bound to the glass base 10. When the cutting is realized by a laser beam, the wavelength of the laser beam may be in any of the infrared, visible and ultraviolet bands. From the viewpoint of reducing the effect of the cutting on the glass base 10, the laser beam desirably has a wavelength in the range of green to ultraviolet. For example, when a Nd:YAG laser apparatus is used, the cutting can be carried out using a second harmonic wave (wavelength: 532 nm) or a third harmonic wave (wavelength: 343 nm or 355 nm). In such a case, the laser power is adjusted to 1 to 3 watts, and the scanning rate is set to about 500 mm per second, so that the multilayer structure supported by the glass base 10 can be cut (divided) into light-emitting devices and unnecessary portions without damaging the glass base 10. According to the embodiment of the present disclosure, the timing of the above-described cutting is earlier than in the prior art. Since the cutting is carried out while the plastic film 30 is bound to the glass base 10, alignment for the cutting can be made with high precision and accuracy even if the gap between adjoining light-emitting devices 1000 is narrow. Thus, the gap between adjoining light-emitting devices 1000 can be shortened, and accordingly, useless portions which are unnecessary for a final product can be reduced. In the prior art, after the delaminating from the glass base 10, a polarizer, a heat radiation sheet, and/or an electromagnetic shield can be adhered to the plastic film 30 so as to cover the entirety of the surface (delaminated surface) of the plastic film 30. In such a case, the polarizer, the heat radiation sheet, and/or the electromagnetic shield are also divided by cutting into portions covering the light-emitting devices 1000 and the remaining unnecessary portions. The unnecessary portions are disposed of as waste. On the other hand, according to the production method of the present disclosure, production of such waste can be suppressed as will be described later. <Lift-Off Light Irradiation> After the intermediate region 30i and respective ones of the plurality of flexible substrate regions 30d of the plastic film 30 are divided from one another, the step of irradiating the interface between the flexible substrate regions 30d of the plastic film 30 and the glass base 10 with laser light is carried out using a lift-off light irradiation unit. FIG. 3A schematically shows a state immediately before the stage 210 supports the multilayer stack 100. In the present embodiment, the stage 210 is a chuck stage which has a large number of pores in the surface for suction. The multilayer stack 100 is arranged such that the second surface 100b of the multilayer stack 100 faces the surface 210S of the stage 210, and is supported by the stage 210. FIG. 3B schematically shows a state where the stage 210 supports the multilayer stack 100. The arrangement of the stage 210 and the multilayer stack 100 is not limited to the example illustrated in the drawing. For example, the multilayer stack 100 may be placed upside down such that the stage 210 is present under the multilayer stack 100. In the example illustrated in FIG. 3B, the multilayer stack 100 is in contact with the surface 210S of the stage 210, and the stage 210 holds the multilayer stack 100 by suction. Then, as shown in FIG. 3C, the interface between the plastic film 30 and the glass base 10 is irradiated with lift-off light 216. FIG. 3C schematically illustrates irradiation of the interface between the glass base 10 and the plastic film 30 of the multilayer stack 100 with the lift-off light 216 in the shape of a line extending in a direction vertical to the sheet of the drawing. A part of the plastic film 30 at the interface between the glass base 10 and the plastic film 30 absorbs the lift-off light 216 and decomposes (disappears). By scanning the above-described interface with the lift-off light 216, the degree of binding of the plastic film 30 to the glass base 10 is reduced. The wavelength of the lift-off light 216 is typically in the ultraviolet band. The wavelength of the lift-off light 216 is selected such that the lift-off light 216 is hardly absorbed by the glass base 10 but is absorbed by the plastic film 30 as much as possible. The light absorption by the glass base 10 is, for example, about 10% in the wavelength range of 343-355 nm but can increase to 30-60% at 308 nm. Hereinafter, lift-off light irradiation according to the present embodiment is described in detail. <Lift-Off Light Irradiation Unit 1> In the present embodiment, the lift-off light irradiation unit includes a line beam source for emitting the lift-off light 216. The line beam source includes a laser apparatus and an optical system for shaping laser light emitted from the laser apparatus into a line beam. In the present disclosure, the lift-off light irradiation unit is referred to as “delaminating apparatus”. FIG. 4A is a perspective view schematically showing irradiation of the multilayer stack 100 with a line beam (lift-off light 216) emitted from a line beam source 214 of a delaminating apparatus 220. For the sake of understandability, the stage 210, the multilayer stack 100 and the line beam source 214 are shown as being spaced away from one another in the Z-axis direction of the drawing. During irradiation with the lift-off light 216, the second surface 100b of the multilayer stack 100 is in contact with the stage 210. The delaminating apparatus 220 includes a controller 300 for controlling the operation of the line beam source 214 and the stage 210. The controller 300 changes the irradiation intensity of lift-off light emitted from the line beam source 214 according to the position of the stage 210. The controller 300 can be a general-purpose computer which has a known configuration. The controller 300 includes, for example, a microprocessor and a nonvolatile memory. In the nonvolatile memory, a program is stored which includes instructions to the microprocessor. FIG. 4B schematically shows the position of the stage 210 during irradiation with the lift-off light 216 (at the start of the first light scanning). Although not shown in FIG. 4B, the multilayer stack 100 is supported by the stage 210. Examples of the laser apparatus that emits the lift-off light 216 include gas laser apparatuses such as excimer laser, solid state laser apparatuses such as YAG laser, semiconductor laser devices, and other types of laser apparatuses. A XeCl excimer laser apparatus can generate laser light at the wavelength of 308 nm. When yttrium orthovanadate (YVO4) doped with neodymium (Nd) or YVO4 doped with ytterbium (Yb) is used as a lasing medium, the wavelength of laser light (fundamental wave) emitted from the lasing medium is about 1000 nm. Therefore, the fundamental wave can be converted by a wavelength converter to laser light at the wavelength of 340-360 nm (third harmonic wave) before it is used. Laser light in the shape of a spot beam emitted from these laser apparatuses is combined with an optical system consisting of lenses and prisms for reshaping the light into the shape of a line beam, whereby lift-off light 216 in the shape of a line beam is produced. In the embodiment of the present disclosure, as will be described later, light scanning is carried out multiple times in different directions (first direction and second direction) relative to the multilayer stack 100. A sacrificial layer or delamination layer (a thin layer of a metal or amorphous silicon) may be provided at the interface between the plastic film 30 and the glass base 10. From the viewpoint of suppressing generation of ashes, using laser light at the wavelength of 308 nm from the excimer laser apparatus, rather than laser light at the wavelength of 340-360 nm, is more effective. Providing the sacrificial layer is highly effective in suppressing generation of ashes. The position of irradiation with the lift-off light 216 moves relative to the glass base 10 for scanning with the lift-off light 216. In the delaminating apparatus 220, the multilayer stack 100 may be movable while the light source 214 from which the lift-off light is to be emitted and an optical unit (not shown) are stationary. Alternatively, the light source 214 may be movable while the multilayer stack 100 is stationary. In the present embodiment, irradiation with the lift-off light 216 is carried out during a period where the stage 210 moves from the position shown in FIG. 4B to the position shown in FIG. 4C. That is, scanning with the lift-off light 216 is carried out by movement of the stage 210 in the X-axis direction (first light scanning). Then, as illustrated in FIG. 4D, the stage 210 rotates by 90° on an axis parallel to the Z-axis. Thereafter, as shown in FIG. 4E, the stage 210 is irradiated with the lift-off light 216 while moving in the negative direction of the X-axis (second light scanning). In each of the first and second light scanning, the irradiation intensity of laser light is modulated such that the irradiation intensity of laser light for at least part of the interface between the intermediate region 30i of the plastic film 30 and the glass base 10 is lower than the irradiation intensity of laser light for the interface between the plurality of flexible substrate regions 30d of the plastic film 30 and the glass base 10. In each of the first and second light scanning, the irradiation intensity of laser light is lower than a threshold level which is necessary for delamination at the interface between the plurality of flexible substrate regions 30d of the plastic film 30 and the glass base 10 through a single scanning cycle. However, the sum of the irradiation intensities of laser light in the first and second light scanning is higher than the threshold level. Hereinafter, details of these two light scanning cycles are described. First, see FIG. 5A to FIG. 5D. FIG. 5A to FIG. 5D are perspective views schematically showing the scanning with the lift-off light 216. In these drawings, the direction of the Z-axis is opposite to the direction of the Z-axis of FIG. 4A to FIG. 4C. In FIG. 5A, the rays of the lift-off light 216 are represented by broken line arrows. In FIG. 5B to FIG. 5D, the rays of the lift-off light 216 are represented by solid line arrows. The broken line arrows represent rays whose irradiation intensity is relatively low as compared with the solid line arrows. The state of FIG. 5D corresponds to the state of FIG. 4D. The stage 210 of FIG. 5D results from rotation of the stage 210 of FIG. 5C by 90° on an axis parallel to the Z-axis. In the present embodiment, scanning with the lift-off light 216 is first carried out along the longer side of the multilayer stack 100 and then carried out along the shorter side of the multilayer stack 100. Such an order is arbitrary. In the present embodiment, the lift-off light 216 is a line beam extending in a direction parallel to the peripheral edge of the glass base 10 (in this example, the Y-axis direction). This line beam is emitted from the line beam source 214 shown in FIG. 4A and other drawings. The irradiation position of the lift-off light 216 on the multilayer stack 100 can be moved not only in the positive direction of the X-axis but also in the negative direction of the X-axis with the passage of time as shown in FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D. Next, see FIG. 6. FIG. 6 is a diagram schematically showing an example of the distribution in the Y-axis direction of the irradiation intensity of the lift-off light 216. In the graph of FIG. 6, the horizontal axis represents the Y-axis coordinate of the irradiation region, and the vertical axis represents the irradiation intensity. The irradiation intensity is expressed by the energy density per unit area (e.g., [mJ/cm2]). In the graph of FIG. 6, specific values of the irradiation intensity are not shown. The irradiation intensity refers to a value in the range of, for example, not less than 0 mJ/cm2 and not more than 500 mJ/cm2. In the graph of FIG. 6, a solid line represents the Y-axis direction distribution I(Y) of the irradiation intensity, and a dot-chain line represents threshold level Th of the irradiation intensity which is necessary for delamination. In the present disclosure, the “threshold level” means a level at which the plastic film 30 sufficiently delaminates from the glass base 10. Threshold level Th is, for example, 250-300 mJ/cm2. When a sacrificial layer is provided between the plastic film 30 and the glass base 10, threshold level Th can be increased to, for example, 300-600 mJ/cm2. Finally, in a region irradiated with lift-off light at an irradiation intensity lower than this threshold level Th, the amount of lift-off light absorbed by the plastic film 30 is insufficient. Therefore, the plastic film 30 in that region remains bound, without being delaminated from the glass base 10. According to the present embodiment, the irradiation intensity does not exceed threshold level Th at any position through a single light scanning cycle. In FIG. 6, a cross section of the multilayer stack 100 which is parallel to the YZ plane is shown above the graph for reference. The glass base 10 extends from position Y0 to position Y5. The light-emitting device 1000 on the left-hand side resides in the region extending from position Y1 to position Y2. The light-emitting device 1000 on the right-hand side resides in the region extending from position Y3 to position Y4. In other words, the flexible substrate regions 30d of the plastic film 30 correspond to the region extending from position Y1 to position Y2 and the region extending from position Y3 to position Y4. Meanwhile, the intermediate region 30i of the plastic film 30 corresponds to the region extending from position Y0 to position Y1, the region extending from position Y2 to position Y3, and the region extending from position Y4 to position Y5. In the example of FIG. 6, the irradiation intensity distribution I(Y) of the lift-off light is, for example, in a range of 50% to 98% of threshold level Th in a region larger than the region extending from position Y0 to position Y5. In the present embodiment, the lift-off light is a line beam which is longer than the size in the Y-axis direction of the glass base 10. The irradiation intensity of the line beam achieved through a single scanning cycle is insufficient for delamination. The smallest value of the irradiation intensity distribution I(Y) of the lift-off light during the scanning is, for example, 0 mJ/cm2 but may be greater than 0 mJ/cm2 (e.g., 20-130 mJ/cm2). It is only required that the sum of the irradiation intensities achieved through two lift-off light irradiation cycles does not reach a level which is necessary for delaminating the intermediate region 30i of the plastic film 30 from the glass base 10. In the example of FIG. 6, the irradiation intensity distribution I(Y) of the lift-off light is linear although the embodiment of the present disclosure is not limited to such an example. For example, as in the example illustrated in FIG. 7, a part or the entirety of the irradiation intensity distribution I(Y) of the lift-off light may be curved. When an amorphous semiconductor is heated and crystallized by irradiation with laser light in the shape of a line beam, the irradiation intensity distribution is desired to be uniform in order to achieve uniform crystallinity. On the other hand, when the delamination in the present embodiment is carried out, the line beam does not need to be uniform so long as the irradiation intensity of the lift-off light at the interface which needs delamination exceeds threshold level Th after two scanning cycles. Next, see FIG. 8. FIG. 8 is a diagram schematically showing an example of the distribution in the X-axis direction (scanning direction) of the irradiation intensity of the lift-off light 216. In the graph of FIG. 8, the horizontal axis represents the X-axis coordinate of the irradiation position, and the vertical axis represents the irradiation intensity. In the graph of FIG. 8, a solid line represents the X-axis direction distribution I(X) of the irradiation intensity, and a dot-chain line represents threshold level Th of the irradiation intensity which is necessary for delamination. In FIG. 8, a cross section of the multilayer stack 100 which is parallel to the XZ plane is shown above the graph for reference. This cross section is perpendicular to the cross section of FIG. 6. The glass base 10 extends from position X0 to position X5. The light-emitting device 1000 on the left-hand side in the drawing resides in the region extending from position X1 to position X2. The light-emitting device 1000 on the right-hand side resides in the region extending from position X3 to position X4. In other words, the flexible substrate regions 30d of the plastic film correspond to the region extending from position X1 to position X2 and the region extending from position X3 to position X4. Meanwhile, the intermediate region 30i of the plastic film 30 corresponds to the region extending from position X0 to position X1 (width: W1), the region extending from position X2 to position X3 (width: W3), and the region extending from position X4 to position X5 (width: W2). The intermediate region 30i at the left edge of the plastic film in FIG. 8 (width: W1) includes a region in which the irradiation intensity is sufficiently lower than threshold level Th (width: S1). Meanwhile, the intermediate region 30i at the right edge of the plastic film 30 in FIG. 8 (width: W2) includes another region in which the irradiation intensity is sufficiently lower than threshold level Th (width: S2). Here, W1>S1 and W2>S2 hold. It is preferred that width S1 is not less than 50% of width W1 and width S2 is not less than 50% of width W2. The X-axis direction distribution I(X) of the irradiation intensity represents the whole (total or integral value) of a single scanning cycle with the lift-off light. For example, while the irradiation position of the lift-off light (the position of the center line of the line beam) moves from position X0 to position X5, the region extending from position X4 to position X5 is not irradiated with the lift-off light. In this period, the irradiation intensity of the lift-off light in the region extending from position X4 to position X5 is, as a matter of course, zero. The line width (the short axis dimension, the size in the X-axis direction) of the lift-off light 216 can be, for example, about 0.2 mm (=200 μm). This dimension defines the largeness of the irradiation region at the interface between the plastic film 30 and the glass base 10 at a certain time. The lift-off light 216 can be emitted in the form of a pulsed or continuous wave. Irradiation with the pulsed wave can be carried out at the frequency (the number of shots in one second) of, for example, about 200 times per second. When the lift-off light 216 is a pulsed wave, the scanning speed is determined such that two consecutive shots form partially-overlapping irradiation regions. If, for example, the line width (the short axis dimension, the size in the X-axis direction) of the lift-off light 216 is 0.2 mm and the irradiation position moves at 20 mm per second in the X-axis direction, a gap can occur between neighboring shots so long as the number of shots per second is less than 100. Therefore, the number of shots per second needs to exceed 100. The positioning accuracy of the irradiation position depends on the mechanical forwarding accuracy of the stage 210. When a YAG laser apparatus is used, the line width (the short axis dimension, the size in the X-axis direction) of the lift-off light 216 can be set to, for example,
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