JP2018013697A - Display device and method for making the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device having a new electrophoresis system and a method for making the same.SOLUTION: Such a structure is employed that switches between a display mode of an electrophoresis system and a self-luminous display mode using an organic EL element in the same display area. Namely, there is provided a display device that switches part of a display area of an electrophoresis system to a self-luminous display area using an organic EL element. In an environment with a large amount of external light, the display mode of the electrophoresis system is used to secure a display area, and in an environment with a small amount of external light, part of the display area is switched to a transmission region, so that display is performed by the emission of a luminous element below the transmission region.SELECTED DRAWING: Figure 1

Description

The present invention relates to an object, a method, or a manufacturing method. The present invention also relates to a process, machine, manufacture, or composition (composition of matter). One embodiment of the present invention relates to a display device, a semiconductor device, a light-emitting device, and the like.

In recent years, liquid crystal display devices that can be thinned and are advantageous in terms of manufacturing cost and power consumption have become more popular than other display-type display devices (CRT, plasma television, etc.). In addition, the transmissive type that uses a backlight is widely used as a liquid crystal display device, but there are problems with the vividness of the display and the viewing angle compared to other display methods. It has been continued.

As an image display device that replaces the liquid crystal display device, a display device using a technique such as an electrophoretic method or an electrochromic method is also proposed in Patent Document 1.

JP 2010-282181 A

A display device using an electrophoretic method has a merit that a screen such as paper has a memory function that does not erase characters even when there is no power supply. On the other hand, there is a limit to gradation display because charged particles colored white or black are used. In addition, it is easy to see in an environment where there is sufficient external light, such as outdoors, but it is difficult to see in an environment where the amount of light to the display device is low, for example, a large room with few lights on the ceiling, or outdoors under a cloudy sky. End up.

In addition, since the visibility depends on the direction of the light source, it takes time for the user to adjust the direction of the sun and the direction of the display surface of the display device when outdoors. Further, when the display device is viewed in a vehicle such as a car or a train, it is difficult to continuously view the display device because the moving body changes its orientation and the positional relationship with the light source changes. For this reason, a display device using an electrophoresis method has a limited environment and situation.

As described above, it is desired to improve the display device using a further electrophoresis method.

Accordingly, a display device having a new electrophoresis method and a manufacturing method thereof are provided.

A single display device can be switched between a plurality of display methods in addition to the electrophoresis method.

Specifically, an electrophoretic display mode and a self-luminous display mode using an organic light-emitting element are switched in the same display region. That is, a display device that switches a part of an electrophoretic display region to a self-luminous display region using an organic EL element is provided. In an environment with a lot of external light, the display mode of the electrophoresis system can be secured, and a display area can be secured. Can be displayed.

In the display device, charged particles used in the electrophoretic method are arranged on the side closer to the user's eyes, and the organic EL element is arranged on the far side. In the case of the self-luminous display mode, the charged particles are moved by adjusting the voltage applied to the plurality of electrodes, a light-transmitting region is formed on the organic EL element, and light from the organic EL element is transmitted through. Display is performed through a region having light properties.

In the case of the electrophoretic display mode, high-definition display is possible because the charged particles are moved by adjusting the voltage applied to the plurality of electrodes so that the translucent region is small.

In the case where display is not performed using an organic EL element, it is useful in terms of reliability to move charged particles to a position overlapping with the organic EL element. Damage to an organic EL element and a transistor electrically connected to the organic EL element due to irradiation with light such as direct sunlight can be reduced with charged particles. Accordingly, it can be said that the charged particles also function as an external light protection shutter for the organic EL element and the transistor.

Simultaneously, an electrophoretic display mode and a self-luminous display mode using an organic EL element can be driven in the same display region. In this case, the display becomes a mixed display, and the user can visually recognize the display without selecting an external environment. That is, even if the outside light is strong, the display can be visually recognized by the electrophoretic display area, and the display can be visually recognized by the self-light emitting display mode even in a dark place where the outside light is weak.

Further, when the display device is conserved in an environment where there is a lot of external light, a still image can be maintained without a power source if the display mode is an electrophoretic method. Further, when the power is turned off or power is saved, if the charged particles overlap with the organic EL element or transistor, incident light is reduced and the reliability of the organic EL element and transistor is improved. In the conventional EL display device, external light (ultraviolet light) or the like is incident on the light emitting element, and the light emitting element deteriorates when the EL display device in a power-off state is exposed to external light for a long time. There was a fear. In the display device disclosed in this specification, the incidence of external light can be reduced by moving charged particles, and deterioration of the light-emitting element can be reduced even when exposed to external light for a long time when the power is turned off.

One structure disclosed in this specification includes a first electrode having a light-transmitting property, a second electrode having a light-transmitting property, a third electrode made of the same material as the second electrode, A dispersion medium having a light property, a plurality of types of positively or negatively charged particle groups, and a light emitting element, and the dispersion medium and the particle groups are disposed between the first electrode and the second electrode to emit light The element serves as a first electrode and a second electrode, and the first electrode and the second electrode are applied by a voltage applied to one or more of the first electrode, the second electrode, and the third electrode. In the display device, the light transmittance of the light-emitting element changes through the first electrode, the second electrode, and the dispersion medium.

The particles are charged particles formed from acrylic particles, black carbon, or the like, and the particle size is 0.1 μm or more and 10 μm or less. The charged particles have a positive or negative chargeability. The particle group dispersed in the dispersion medium disposed between the pair of electrodes is moved near one electrode by applying a voltage between the pair of electrodes. In order to perform black and white display, white charged particles and black charged particles having different chargeability from the charged particles are used. In order to perform full color display, a plurality of colored charged particles (for example, a combination of red, green, and blue, a combination of yellow, magenta, and cyan) are used. Further, in the case of taking out light emission of the organic EL element disposed below, a display region having translucency is formed by moving charged particles, and light emission display is obtained in the display region.

In the above configuration, the position of the third electrode is not particularly limited, but by applying a predetermined voltage to the third electrode, the particle group positioned between the first electrode and the second electrode is moved, and the third electrode What is necessary is just to install in the position where only between a 1st electrode and a 2nd electrode becomes a dispersion medium, and between a 1st electrode and a 2nd electrode has translucency.

The display device can be used by automatically or manually switching between a display mode using charged particles and a display mode using an organic EL element according to the external environment (ambient brightness). Furthermore, a display in which both a display mode using charged particles and a display mode using an organic EL element are combined is also possible.

In addition to the electrophoresis method, it is possible to realize a configuration in which a plurality of display methods can be switched.

1 is a cross-sectional view illustrating one embodiment of the present invention. FIG. 6 is a cross-sectional process diagram illustrating one embodiment of the present invention. FIG. 6 is a cross-sectional process diagram illustrating one embodiment of the present invention. FIG. 6 is a cross-sectional process diagram illustrating one embodiment of the present invention. FIG. 6 is a cross-sectional process diagram illustrating one embodiment of the present invention. FIG. 6 is a cross-sectional process diagram illustrating one embodiment of the present invention. FIG. 6 is a cross-sectional process diagram illustrating one embodiment of the present invention. FIG. 6 is a cross-sectional process diagram illustrating one embodiment of the present invention. The figure explaining a display module. 10A and 10B each illustrate an electronic device. FIG. 14 is a perspective view illustrating a display device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that modes and details can be variously changed. In addition, the present invention is not construed as being limited to the description of the embodiments below.

(Embodiment 1)
In this embodiment, a display device of one embodiment of the present invention and a manufacturing method thereof will be described.

  The display device of one embodiment of the present invention has a structure in which an electrophoretic display element and a light-emitting element are stacked. An electrophoretic display element can express gradation by controlling the degree of aggregation of two or more types of charged particles having different chargeability and color for each pixel. In addition, an electrophoretic display element can display a gray scale by area gray scale. The light emitting element can express gradation by controlling the amount of light emitted.

  The electrophoretic display element is provided on the viewing side (the observation position side of the user), and the light emitting element is provided on the side opposite to the viewing side. Light emitted from the light-emitting element can pass through a light-transmitting region obtained by moving an electrophoretic particle group, and can be emitted to the viewing side.

  The display device can be an active matrix display device in which an electrophoretic display element and a light-emitting element are each electrically connected to a transistor.

  At this time, the display device is electrically connected to the first element layer including the first transistor electrically connected to the light emitting element, the second element layer including the light emitting element, and the electrophoretic display element. A third element layer including two transistors and a fourth element layer including an electrophoretic display element. Then, the first element layer, the second element layer, the third element layer, and the fourth element layer are laminated in this order from the side opposite to the visual recognition.

  Here, it is preferable to provide resin layers (a first resin layer and a second resin layer) on the viewing side with respect to the fourth element layer and on the side opposite to the viewing side of the first element layer, respectively. As a result, the display device can be made extremely light, and the display device can be made difficult to break.

  The first resin layer and the second resin layer (hereinafter collectively referred to as a resin layer) are extremely thin. More specifically, the thickness is preferably 0.1 μm or more and 3 μm or less. Therefore, even if it is the structure which laminated | stacked two display panels, thickness can be made thin. In addition, even when a resin layer is disposed on the path of light emitted from the light emitting element, light absorption is suppressed because the resin layer is thin, light can be extracted with higher efficiency, and power consumption can be reduced. Can be small.

  The resin layer can be formed as follows, for example. That is, a low-viscosity thermosetting resin material is applied on a support substrate and cured by heat treatment to form a resin layer. Then, a structure is formed on the resin layer. Then, one surface of the resin layer is exposed by peeling between the resin layer and the support substrate.

  When the support substrate and the resin layer are peeled off, laser light may be irradiated as a method for reducing the adhesion. For example, it is preferable to irradiate the laser beam by using a linear laser as the laser beam and scanning it. Thereby, the process time at the time of enlarging the area of a support substrate can be shortened. As the laser light, an excimer laser having a wavelength of 308 nm can be suitably used.

  A typical example of a material that can be used for the resin layer is thermosetting polyimide. It is particularly preferable to use photosensitive polyimide. Since photosensitive polyimide is a material that is suitably used for a planarization film or the like of a display panel, a forming apparatus and a material can be shared. Therefore, no new device or material is required to realize the structure of one embodiment of the present invention.

  Further, by using a photosensitive resin material for the resin layer, the resin layer can be processed by performing exposure and development processing. For example, an opening can be formed or an unnecessary portion can be removed. Further, by optimizing the exposure method and exposure conditions, it is possible to form a concavo-convex shape on the surface. For example, an exposure technique using a halftone mask or a gray tone mask, a multiple exposure technique, or the like may be used.

  A non-photosensitive resin material may be used. At this time, a method of forming a resist mask or a hard mask on the resin layer to form an opening or an uneven shape can also be used.

  In addition, it is preferable to partially remove the resin layer located on the light path from the light emitting element. That is, an opening that overlaps with the light-emitting element is provided in the first resin layer. Thereby, the fall of the color reproducibility accompanying a part of light from a light emitting element being absorbed by the resin layer, and the fall of light extraction efficiency can be suppressed.

  Or it is good also as a structure by which the recessed part was formed in the resin layer so that the part located on the path | route of the light from the light emitting element of a resin layer may become thinner than another part. That is, the resin layer may have two portions with different thicknesses, and the thin portion may overlap the light emitting element. Even with this configuration, absorption of light from the light emitting element by the resin layer can be reduced.

  Alternatively, the following method can also be used. A light absorption layer is formed over the support substrate, a resin layer having an opening is formed over the light absorption layer, and a light-transmitting layer covering the opening is further formed. The light absorption layer is a layer that emits a gas such as hydrogen or oxygen when heated by absorbing light. Therefore, by irradiating light from the support substrate side and releasing the gas from the light absorption layer, the adhesion between the light absorption layer and the support substrate or between the light absorption layer and the light transmitting layer is reduced. , Peeling can occur. Alternatively, the light absorption layer itself can be broken and peeled off.

  For the first transistor and the second transistor, an oxide semiconductor is preferably used as a semiconductor for forming a channel. An oxide semiconductor can achieve a high on-state current and ensure high reliability even when the maximum temperature in the manufacturing process of the transistor is reduced (for example, 400 ° C. or lower, preferably 350 ° C. or lower). In addition, when an oxide semiconductor is used, high heat resistance is not required as a material used for the resin layer located on the formation surface of the transistor, so that the range of selection of materials can be widened. For example, it can also serve as a resin material used as a planarizing film.

  On the other hand, in the case of using an oxide semiconductor, a special material having high heat resistance is not necessary and needs to be formed thick, so that the cost ratio of the resin layer to the entire display panel can be reduced.

  An oxide semiconductor has a wide band gap (eg, 2.5 eV or more, or 3.0 eV or more) and a property of transmitting light. Therefore, in the step of separating the support substrate and the resin layer, even if laser light is irradiated to the oxide semiconductor, it is difficult to absorb, and thus the influence on the electrical characteristics can be suppressed. Therefore, the resin layer can be thinly formed as described above.

  One embodiment of the present invention is a resin layer that is thinly formed using a low-viscosity photosensitive resin material typified by photosensitive polyimide, and an oxide semiconductor that can realize a transistor with excellent electrical characteristics even at low temperatures. By combining these, a display device with extremely high productivity can be realized.

  Next, the configuration of the pixel will be described. The display device can include a first pixel including a light-emitting element and a first transistor, and a second pixel including an electrophoretic display element and a second transistor. A plurality of first pixels and second pixels are arranged in a matrix, respectively, and constitute a display unit. In addition, the display device preferably includes a first driving unit that drives the first pixel and a second driving unit that drives the second pixel.

  According to one embodiment of the present invention, a first mode in which an image is displayed with a first pixel, a second mode in which an image is displayed with a second pixel, and an image is displayed with the first pixel and the second pixel. The third mode can be switched.

  Next, a transistor that can be used for a display device will be described. The first transistor and the second transistor may be transistors having the same configuration, or may be different transistors.

  As a structure of the transistor, for example, a bottom-gate transistor can be given. A bottom-gate transistor has a gate electrode on the lower side (formation surface side) than the semiconductor layer. In addition, for example, a source electrode and a drain electrode are provided in contact with the upper surface and side end portions of the semiconductor layer.

  As another structure of the transistor, for example, a top-gate transistor can be given. A top-gate transistor has a gate electrode above the semiconductor layer (on the side opposite to the formation surface). In addition, for example, the first source electrode and the first drain electrode are provided over the insulating layer that covers a part of the upper surface and the side end of the semiconductor layer, and the semiconductor layer is provided through the opening provided in the insulating layer. It is electrically connected to.

  The transistor preferably includes a first gate electrode and a second gate electrode which are provided to face each other with a semiconductor layer interposed therebetween.

  Hereinafter, a more specific example of the display device of one embodiment of the present invention will be described with reference to drawings.

  In the following, expressions indicating the direction such as “up” and “down” are basically used in combination with the direction of the drawing. However, for the purpose of facilitating the description and the like, the direction indicated by “upper” or “lower” in the specification may not match the drawing. As an example, when explaining the stacking order (or forming order) of a laminated body or the like, the surface (formation surface, support surface, adhesive surface, flat surface, etc.) on the side where the laminated body is provided in the drawing Even if it is positioned above the laminated body, the direction may be expressed as “down”, the opposite direction may be expressed as “up”, and the like.

  FIG. 1A shows a schematic cross-sectional view of the display device 10. The display device 10 has a configuration in which an element layer 100 and an element layer 200 are stacked in this order. The display device 10 includes a substrate 11 on the back side (the side opposite to the viewing side) and a substrate 12 on the front side (viewing side). Further, a resin layer 101 is provided between the substrate 11 and the element layer 100, and an adhesive layer 52 is provided between the substrate 12 and the element layer 200. The resin layer 101 and the substrate 11 are bonded together by an adhesive layer 51. The substrate 12 is bonded by an adhesive layer 52.

  The element layer 100 includes the transistor 110 over the resin layer 101. The element layer 100 includes a light-emitting element 120 that is electrically connected to the transistor 110. The element layer 200 includes a transistor 210. The element layer 200 includes an electrophoretic display element 240 electrically connected to the transistor 210.

[Element layer 100]
Over the resin layer 101, a transistor 110, a light-emitting element 120, an insulating layer 131, an insulating layer 132, an insulating layer 133, an insulating layer 134, an insulating layer 135, and the like are provided.

  The transistor 110 includes a conductive layer 111 functioning as a gate electrode, a part of the insulating layer 132 functioning as a gate insulating layer, a semiconductor layer 112, a conductive layer 113a functioning as one of a source electrode and a drain electrode, and a source electrode Or a conductive layer 113b functioning as the other of the drain electrodes.

  The semiconductor layer 112 preferably includes an oxide semiconductor.

  The insulating layer 133 and the insulating layer 134 are provided so as to cover the transistor 110. The insulating layer 134 functions as a planarization layer.

  The light-emitting element 120 has a structure in which a conductive layer 121, an EL layer 122, and a conductive layer 123 are stacked. The conductive layer 121 has a function of reflecting visible light, and the conductive layer 123 has a function of transmitting visible light. Therefore, the light-emitting element 120 is a top-emission type (also referred to as top-emission type) light-emitting element that emits light to the side opposite to a formation surface.

  The conductive layer 121 is electrically connected to the conductive layer 113b through an opening provided in the insulating layer 134 and the insulating layer 133. The insulating layer 135 covers an end portion of the conductive layer 121 and has an opening so that a part of the surface of the conductive layer 121 is exposed. The EL layer 122 and the conductive layer 123 are sequentially provided so as to cover the exposed portions of the insulating layer 135 and the conductive layer 121.

  The light emitting element 120 is sealed with an adhesive layer 151. In addition, the element layer 200a and the element layer 100b are bonded to each other with an adhesive layer 151.

  Here, a stacked structure including the insulating layer 131, the insulating layer 132, the insulating layer 133, the insulating layer 134, the transistor 110, the insulating layer 135, and the light-emitting element 120 is referred to as an element layer 100. Note that the element layer 100 may include a coloring layer 152 and a light shielding layer 153 described later.

[Element layer 200]
The element layer 200 includes at least a transistor 210 and an electrophoretic display element 240. One electrophoretic display element 240 includes a conductive layer 221 a, a conductive layer 223 a, a dispersion medium 243, first charged particles 241, and second charged particles 242. The dispersion medium 243 is a light-transmitting dispersion fluid, and uses a nonpolar organic solvent such as paraffinic hydrocarbon, aromatic hydrocarbon, silicone oil, and the like to form a region where the charged particle group can move. In this specification, the dispersion medium refers to a portion of the liquid excluding the charged particles that move with current or voltage, and includes a dispersant or a charge control agent for dispersing the charged particles. The distance between the conductive layer 221a and the conductive layer 223a may be held by a gap material, and a spherical spacer, a glass rod, a columnar spacer patterned with a resin film, or the like may be used. These components are not included in the dispersion medium.

The first charged particles 241 and the second charged particles 242 have different colors, and here, two examples, white and black, are shown. The charged particles have an average particle size of 0.01 μm or more and 10 μm or less, and resin particles, ceramic particles, metal oxide particles, pigment particles, dye particles or the like are used as materials, or composite particles thereof are used. The composite particles are those in which the surface of resin particles is coated with a pigment, or a mixture in which a pigment and a resin material are mixed. For example, solid particles of metal oxide such as aluminum oxide and titanium oxide can be used as charged particles for white display. As charged particles for black display, solid particles such as aniline black, carbon black and titanium black can be used.

In the case of full color, instead of white display charged particles, yellow display charged particles, red display charged particles, green display charged particles, or blue display charged particles may be used. . In the case of full color, charged particles for yellow display, charged particles for cyan display, or charged particles for magenta display may be used. For example, chrome yellow may be used as yellow display particles, quinacridone red may be used as red display particles, and phthalocyanine blue pigments may be used as blue display particles.

  Further, the dispersion medium 243 is sealed around the periphery thereof by an adhesive layer in a region not shown.

  An insulating layer 231 is provided to cover the conductive layer 221a. The transistor 210 is formed with a surface of the insulating layer 231 opposite to the conductive layer 221a side as a formation surface.

The conductive layer 221c is formed of the same material as the conductive layer 221a and is formed in the same process, and a voltage is applied between the conductive layer 223c and the conductive layer 223c so as to overlap with the first charged particle 241 and the second charged particle 242. Position control is performed and display is performed.

In order to transmit light emitted from the light-emitting element 120, the conductive layer 221b is formed using a light-transmitting conductive material. Further, a negative or positive voltage is applied to the conductive layer 221b in order to move the charged particles overlapping above the conductive layer 221b. Further, in order to prevent a short circuit with an adjacent conductive layer, the insulating layer 244 is used. Further, the conductive layer 223b that overlaps with the dispersion medium 243 may be short-circuited, and thus a structure covered with the insulating layer 244 is useful. In addition, the conductive layer 223b is configured to be covered with the insulating layer 245 because a voltage different from that of the adjacent conductive layer 223a or the conductive layer 223c may be applied and there is a risk of a short circuit.

  The transistor 210 includes a conductive layer 211 functioning as a gate electrode, a part of the insulating layer 232 functioning as a gate insulating layer, a semiconductor layer 212, a conductive layer 213a functioning as one of a source electrode and a drain electrode, and a source electrode Or a conductive layer 213b functioning as the other of the drain electrodes.

  The semiconductor layer 212 preferably includes an oxide semiconductor.

  The insulating layer 233 and the insulating layer 234 are provided so as to cover the transistor 210. The insulating layer 234 functions as a planarization layer.

  The conductive layer 213b is electrically connected to the conductive layer 221a through an opening provided in the insulating layer 232 and the insulating layer 231.

  A colored layer 152 and a light shielding layer 153 are provided on the surface of the insulating layer 234 on the substrate 11 side. The colored layer 152 is provided at a position overlapping the light emitting element 120. In addition, the light shielding layer 153 has an opening in a portion overlapping with the light emitting element 120.

[Display device 10]
The display device 10 illustrated in FIG. 1A illustrates an example in which when viewed from above, a region overlapping with the conductive layer 223a displays white, a region 31 displays black, and a region overlapping 223c displays white. As shown in FIG. 1A, reflected light 22a in which external light is reflected by the first charged particles 241 enters the eyes of the user, and a region overlapping with the conductive layer 223a is recognized as white. Also in the region 31, the reflected light 22b in which the external light is reflected by the first charged particles 241 enters the user's eyes, and the region overlapping the conductive layer 223b is recognized as white. In the case of black, the second charged particles 242 may be collected so as to be in contact with the conductive layer 223a by controlling the second charged particles 242 according to the voltage of the conductive layer 223a or a voltage application sequence. Note that even if light is emitted from the light emitting element 120, the light is shielded by the first charged particles 241 and the second charged particles 242.

Further, as shown in FIG. 1B, the region 31 is made to be a region where no charged particles exist by applying a voltage or a voltage application sequence to the conductive layer 223b and the conductive layer 221b. The light emission 21 colored by the coloring layer 152 passes through the light-transmitting dispersion medium 243 and is emitted to the viewing side. In FIG. 1B, similarly to FIG. 1A, the reflected light 22a in which the external light is reflected by the first charged particles 241 enters the user's eyes in a region overlapping with the conductive layer 223a. A region overlapping with the conductive layer 223a is recognized as white.

In other words, in the region 31, it is possible to switch between electrophoretic display and light emission display from the light emitting element 120.

  Moreover, although the glass substrate etc. may be used for the board | substrate 11 and the board | substrate 12, it is preferable to use the material containing resin. When the resin material is used, the display device 10 can be reduced in weight as compared with the case where glass or the like is used even if the thickness is the same. In addition, it is preferable to use a material that is thin enough to have flexibility (including a glass substrate or the like) because the weight can be further reduced. Further, by using a resin material, the impact resistance of the display device can be improved, and a display device that is difficult to break can be realized.

  Moreover, since the board | substrate 11 is a board | substrate located in the opposite side to the visual recognition side, it does not need to have translucency with respect to visible light. Therefore, a metal material can also be used. Since the metal material has high thermal conductivity and can easily conduct heat to the entire substrate, local temperature rise of the display device 10 can be suppressed.

  The above is the description of the configuration example.

[Example of production method]
Hereinafter, an example of a method for manufacturing the display device 10 illustrated in FIG. 1 will be described with reference to the drawings.

  Note that a thin film (an insulating film, a semiconductor film, a conductive film, or the like) included in the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, or a pulse laser deposition (PLD: Pulse Laser Deposition). ) Method, atomic layer deposition (ALD: Atomic Layer Deposition) method, or the like. The CVD method may be a plasma enhanced chemical vapor deposition (PECVD) method or a thermal CVD method. As an example of the thermal CVD method, a metal organic chemical vapor deposition (MOCVD) method may be used.

  Thin films (insulating films, semiconductor films, conductive films, etc.) that constitute display devices are spin coat, dip, spray coating, ink jet, dispense, screen printing, offset printing, doctor knife, slit coat, roll coat, curtain coat. It can be formed by a method such as knife coating.

  Further, when a thin film included in the display device is processed, the thin film can be processed using a photolithography method or the like. Alternatively, an island-shaped thin film may be formed by a film formation method using a shielding mask. Alternatively, the thin film may be processed by a nanoimprint method, a sand blast method, a lift-off method, or the like. As a photolithographic method, a photosensitive resist material is applied onto a thin film to be processed, exposed using a photomask, developed to form a resist mask, and the thin film is processed by etching or the like. There are a method of removing the resist mask and a method of forming a photosensitive thin film and then performing exposure and development to process the thin film into a desired shape.

  In photolithography, light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or light obtained by mixing these. In addition, ultraviolet light, KrF laser light, ArF laser light, or the like can be used. Further, exposure may be performed by an immersion exposure technique. Further, extreme ultraviolet light (EUV: Extreme Ultra-violet) or X-rays may be used as light used for exposure. Further, an electron beam can be used instead of the light used for exposure. It is preferable to use extreme ultraviolet light, X-rays, or an electron beam because extremely fine processing is possible. Note that a photomask is not required when exposure is performed by scanning a beam such as light or an electron beam.

  For etching the thin film, a dry etching method, a wet etching method, a sand blasting method, or the like can be used.

  First, a method for forming the element layer 100 will be described.

[Preparation of support substrate]
First, the support substrate 61 is prepared. As the support substrate 61, a material that is rigid to such an extent that it can be easily transported and that is heat resistant to the temperature required for the manufacturing process can be used. For example, materials such as glass, quartz, ceramic, sapphire, organic resin, semiconductor, metal, or alloy can be used. As the glass, for example, alkali-free glass, barium borosilicate glass, alumino borosilicate glass, or the like can be used.

[Formation of resin layer]
Subsequently, the resin layer 101 is formed over the support substrate 61 (FIG. 2B).

  First, a material to be the resin layer 101 is applied on the support substrate 61. The application is preferably performed by spin coating because a thin resin layer 101 can be uniformly formed on a large substrate.

  As other coating methods, methods such as dip, spray coating, ink jet, dispensing, screen printing, offset printing, doctor knife, slit coating, roll coating, curtain coating, and knife coating may be used.

  The material has a polymerizable monomer that exhibits thermosetting (also referred to as thermopolymerization) in which polymerization proceeds by heat. Furthermore, the material preferably has photosensitivity. Moreover, it is preferable that the said material contains the solvent for adjusting a viscosity.

  The material preferably contains a polymerizable monomer that becomes a polyimide resin, an acrylic resin, an epoxy resin, a polyamide resin, a polyimide amide resin, a siloxane resin, a benzocyclobutene resin, or a phenol resin after polymerization. That is, the formed resin layer 101 includes these resin materials. In particular, by using a polymerizable monomer having an imide bond as the material, it is preferable to use a resin typified by a polyimide resin for the resin layer 101 because heat resistance and weather resistance can be improved.

  The viscosity of the material used for coating is 5 cP or more and less than 500 cP, preferably the viscosity is 5 cP or more and less than 100 cP, and more preferably the viscosity is 10 cP or more and 50 cP or less. The lower the viscosity of the material, the easier it is to apply. In addition, the lower the viscosity of the material, the more air bubbles can be prevented and the better the film can be formed. Further, the lower the viscosity of the material, the thinner and more uniformly it can be applied, so that a thinner resin layer 101 can be formed.

  Here, when a photosensitive material is used for the resin layer 101, a part thereof can be removed by a photolithography method. For example, after applying the material, heat treatment for removing the solvent (also referred to as pre-bake treatment) is performed, and then exposure is performed. Subsequently, unnecessary portions can be removed by performing development processing.

  More specifically, a method for forming the resin layer 101 having openings will be described. First, a photosensitive material is applied to form a thin film, and a heat treatment (pre-bake treatment) for removing the solvent and the like is performed. Subsequently, the material is exposed using a photomask and developed, whereby the resin layer 101 having an opening or a recess can be formed.

  Subsequently, the resin layer 101 is formed by performing a heat treatment (post-bake treatment) for polymerizing the applied material. The heating is preferably performed at a temperature higher than the maximum temperature required for a manufacturing process of the transistor 110 later. For example, it is preferable to heat at 300 ° C. to 600 ° C., preferably 350 ° C. to 550 ° C., more preferably 400 ° C. to 500 ° C., typically 450 ° C. When the resin layer 101 is formed, by heating at such a temperature with the surface exposed, the gas that can be desorbed from the resin layer 101 can be removed, so that the gas is desorbed during the manufacturing process of the transistor 110. Can be suppressed.

  The thickness of the resin layer 101 is preferably 0.01 μm or more and less than 10 μm, more preferably 0.1 μm or more and 3 μm or less, and further preferably 0.5 μm or more and 1 μm or less. By using a low-viscosity solution, it becomes easy to form the resin layer 101 thinly and uniformly.

  Further, the thermal expansion coefficient of the resin layer 101 is preferably 0.1 ppm / ° C. or more and 20 ppm / ° C. or less, and more preferably 0.1 ppm / ° C. or more and 10 ppm / ° C. or less. As the thermal expansion coefficient of the resin layer 101 is lower, the transistor or the like can be prevented from being damaged by the stress accompanying expansion or contraction due to heating.

  In the case where an oxide semiconductor film is used for the semiconductor layer 112 of the transistor 110, the resin layer 101 is not required to have high heat resistance because it can be formed at a low temperature. Therefore, the cost of the material can be reduced. The heat resistance of the resin layer 101 and the like can be evaluated by, for example, a weight reduction rate by heating, specifically, a 5% weight reduction temperature. The 5% weight reduction temperature of the resin layer 101 or the like can be set to 450 ° C. or lower, preferably 400 ° C. or lower, more preferably lower than 400 ° C., and still more preferably lower than 350 ° C. In addition, it is preferable that the maximum temperature in the formation process of the transistor 110 and the like be 350 ° C. or lower.

  By providing an opening in the resin layer 101 by the above method, the following configuration can be realized. For example, by disposing the conductive layer so as to cover the opening, an electrode partially exposed on the back surface side (also referred to as a back electrode or a through electrode) can be formed after the peeling step described later. The electrode can also be used as an external connection terminal. Further, for example, by removing the resin layer 101 at a position overlapping the marker portion for bonding two support substrates and the like, the alignment accuracy can be increased.

[Formation of Insulating Layer 131]
Subsequently, an insulating layer 131 is formed over the resin layer 101 (FIG. 2B).

  The insulating layer 131 can be used as a barrier layer that prevents impurities contained in the resin layer 101 from diffusing into a transistor or a light-emitting element to be formed later. Therefore, it is preferable to use a material having a high barrier property.

  As the material having a high barrier property, for example, an inorganic insulating material such as a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, or an aluminum nitride film can be used. Alternatively, two or more of the above insulating films may be stacked. In particular, a stacked film of a silicon nitride film and a silicon oxide film is preferably used from the resin layer 101 side.

  In the case where the surface of the resin layer 101 has unevenness, the insulating layer 131 preferably covers the unevenness. The insulating layer 131 may function as a planarization layer that planarizes the unevenness. For example, the insulating layer 131 is preferably formed using a stack of an organic insulating material and an inorganic insulating material. Organic resins such as epoxy resin, acrylic resin, silicone resin, phenol resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, EVA (ethylene vinyl acetate) resin, etc. Can be used.

  The insulating layer 131 is preferably formed at a temperature of, for example, room temperature to 400 ° C., preferably 100 ° C. to 350 ° C., more preferably 150 ° C. to 300 ° C.

[Formation of transistors]
Next, as illustrated in FIG. 2C, the transistor 110 is formed over the insulating layer 131. Here, as an example of the transistor 110, an example in the case of manufacturing a bottom-gate transistor is shown.

  A conductive layer 111 is formed over the insulating layer 131. The conductive layer 111 can be formed by forming a conductive film, forming a resist mask, etching the conductive film, and then removing the resist mask.

  Subsequently, the insulating layer 132 is formed. As the insulating layer 132, an inorganic insulating film that can be used for the insulating layer 131 can be used.

  Subsequently, the semiconductor layer 112 is formed. The semiconductor layer 112 can be formed by forming a semiconductor film, forming a resist mask, etching the semiconductor film, and then removing the resist mask.

  The semiconductor film is formed at a substrate temperature during film formation of room temperature to 300 ° C., preferably room temperature to 220 ° C., more preferably room temperature to 200 ° C., more preferably room temperature to 170 ° C. Here, that the substrate temperature during film formation is room temperature indicates that the substrate is not intentionally heated. At this time, a case where the temperature is higher than room temperature due to energy received by the substrate during film formation is included. The room temperature refers to a temperature range of 10 ° C. to 30 ° C., for example, and is typically 25 ° C.

  As the semiconductor film, an oxide semiconductor is preferably used. In particular, an oxide semiconductor having a larger band gap than silicon is preferably used. It is preferable to use a semiconductor material with a wider band gap and lower carrier density than silicon because current in an off state of the transistor can be reduced.

  As the oxide semiconductor, a material having a band gap of 2.5 eV or more, preferably 2.8 eV or more, more preferably 3.0 eV or more is preferably used. With the use of such an oxide semiconductor, the light is transmitted through the semiconductor film in irradiation with light such as laser light in a peeling step which will be described later, so that adverse effects on the electrical characteristics of the transistor are less likely to occur.

  In particular, the semiconductor film used for one embodiment of the present invention is preferably formed by a sputtering method in an atmosphere containing one or both of an inert gas (eg, Ar) and an oxygen gas.

  The substrate temperature at the time of film formation is preferably room temperature to 200 ° C., preferably room temperature to 170 ° C. By increasing the temperature of the substrate, more crystal parts having orientation are formed, and a semiconductor film having excellent electrical stability can be formed. By using such a semiconductor film, a transistor with excellent electrical stability can be realized. In addition, by forming the film at a low substrate temperature or without intentional heating, a semiconductor film with a low carrier ratio and a high carrier mobility can be formed. By using such a semiconductor film, a transistor exhibiting high field effect mobility can be realized.

  In addition, the flow rate ratio of oxygen during film formation (oxygen partial pressure) is 0% to less than 100%, preferably 0% to 50%, more preferably 0% to 33%, and still more preferably 0% to 15%. % Or less is preferable. By reducing the oxygen flow rate, a semiconductor film with high carrier mobility can be formed, and a transistor exhibiting higher field-effect mobility can be realized. On the other hand, by increasing the flow ratio of oxygen, a semiconductor film with high crystallinity can be formed, and a semiconductor film with excellent electrical stability can be obtained.

  By setting the substrate temperature during film formation and the oxygen flow rate during film formation within the above ranges, a semiconductor film in which crystal parts having orientation and crystal parts having no orientation are mixed can be obtained. . Further, by optimizing the substrate temperature and the oxygen flow rate within the above-described ranges, it is possible to control the existence ratio of the crystal part having orientation and the crystal part not having orientation.

  An oxide target that can be used for forming a semiconductor film is not limited to an In—Ga—Zn-based oxide. For example, an In—M—Zn-based oxide (M is Al, Y, or Sn). Can be applied.

  Further, when a semiconductor film including a crystal part, which is a semiconductor film, is formed using a sputtering target including a polycrystalline oxide having a plurality of crystal grains, the sputtering target not including a polycrystalline oxide is used. Thus, it is easy to obtain a crystalline semiconductor film.

  In particular, the crystal part having orientation in the thickness direction of the film (also referred to as the film surface direction, the film formation surface, or the direction perpendicular to the film surface), and disorderly without such orientation A transistor using a semiconductor film in which oriented crystal parts are mixed has characteristics such as high stability of electric characteristics and easy miniaturization of a channel length. On the other hand, a transistor to which a semiconductor film including only crystal parts having no orientation is applied can increase field effect mobility. Note that as described later, by reducing oxygen vacancies in the oxide semiconductor, a transistor having both high field-effect mobility and high stability of electric characteristics can be realized.

  In this manner, by using an oxide semiconductor film, heat treatment at a high temperature and laser crystallization treatment that are necessary for LTPS are unnecessary, and the semiconductor layer 112 can be formed at an extremely low temperature. Therefore, the resin layer 101 can be formed thin.

  Subsequently, a conductive layer 113a and a conductive layer 113b are formed. The conductive layers 113a and 113b can be formed by forming a conductive film, forming a resist mask, etching the conductive film, and then removing the resist mask.

  Note that part of the semiconductor layer 112 that is not covered with the resist mask may be thinned by etching when the conductive layer 113a and the conductive layer 113b are processed. It is preferable to use an oxide semiconductor film including a crystal part having orientation as the semiconductor layer 112 because this thinning can be suppressed.

  As described above, the transistor 110 can be manufactured. The transistor 110 is a transistor including an oxide semiconductor in the semiconductor layer 112 in which a channel is formed. In the transistor 110, part of the conductive layer 111 functions as a gate, part of the insulating layer 132 functions as a gate insulating layer, and the conductive layers 113a and 113b each function as either a source or a drain. To do.

[Formation of Insulating Layer 133]
Subsequently, an insulating layer 133 that covers the transistor 110 is formed. The insulating layer 133 can be formed by a method similar to that of the insulating layer 132.

  The insulating layer 133 is preferably formed at a temperature of, for example, room temperature to 400 ° C., preferably 100 ° C. to 350 ° C., more preferably 150 ° C. to 300 ° C. The higher the temperature, the denser the barrier film can be.

  As the insulating layer 133, an oxide insulating film such as a silicon oxide film or a silicon oxynitride film formed at a low temperature as described above in an atmosphere containing oxygen is preferably used. In addition, an insulating film that hardly diffuses and transmits oxygen such as a silicon nitride film is preferably stacked over the silicon oxide or silicon oxynitride film. An oxide insulating film formed at a low temperature in an atmosphere containing oxygen can be an insulating film from which a large amount of oxygen is easily released by heating. Oxygen can be supplied to the semiconductor layer 112 by performing heat treatment in a state where such an oxide insulating film that emits oxygen and an insulating film that hardly diffuses and transmits oxygen are stacked. As a result, oxygen vacancies in the semiconductor layer 112 and defects at the interface between the semiconductor layer 112 and the insulating layer 133 can be repaired, and the defect level can be reduced. Thereby, a highly reliable semiconductor device can be realized.

  Through the above steps, the transistor 110 and the insulating layer 133 covering the transistor 110 can be formed over the flexible resin layer 101. Note that at this stage, a flexible device having no display element can be manufactured by separating the resin layer 101 and the support substrate 61 using a method described later. For example, a flexible device including a semiconductor circuit can be manufactured by forming a transistor 110, a capacitor, a resistor, a wiring, and the like in addition to the transistor 110.

[Formation of Insulating Layer 134]
Subsequently, the insulating layer 134 is formed over the insulating layer 133. The insulating layer 134 is a layer having a formation surface of a display element to be formed later, and thus is preferably a layer that functions as a planarization layer. As the insulating layer 134, an organic insulating film or an inorganic insulating film that can be used for the insulating layer 131 can be used.

  As with the resin layer 101, the insulating layer 134 is preferably formed using a resin material having photosensitivity and thermosetting. In particular, it is preferable to use the same material for the insulating layer 134 and the resin layer 101. Thereby, it is possible to share the materials for the insulating layer 134 and the resin layer 101 and the apparatus for forming them.

  Further, like the resin layer 101, the insulating layer 134 is preferably 0.01 μm or more and less than 10 μm, more preferably 0.1 μm or more and 3 μm or less, and further preferably 0.5 μm or more and 1 μm or less. preferable. By using a low-viscosity solution, it becomes easy to form the insulating layer 134 thinly and uniformly.

[Formation of Light Emitting Element 120]
Subsequently, an opening reaching the conductive layer 113b and the like is formed in the insulating layer 134 and the insulating layer 133.

  Thereafter, the conductive layer 121 is formed. Part of the conductive layer 121 functions as a pixel electrode. The conductive layer 121 can be formed by forming a conductive film, forming a resist mask, etching the conductive film, and then removing the resist mask.

  Next, as illustrated in FIG. 2D, an insulating layer 135 that covers an end portion of the conductive layer 121 is formed. As the insulating layer 135, an organic insulating film or an inorganic insulating film that can be used for the insulating layer 131 can be used.

  As with the resin layer 101, the insulating layer 135 is preferably formed using a resin material having photosensitivity and thermosetting. In particular, the same material is preferably used for the insulating layer 135 and the resin layer 101. Thereby, it is possible to share the materials for the insulating layer 135 and the resin layer 101 and the apparatus for forming them.

  Further, like the resin layer 101, the insulating layer 135 is preferably 0.01 μm or more and less than 10 μm, more preferably 0.1 μm or more and 3 μm or less, and further preferably 0.5 μm or more and 1 μm or less. preferable. By using a low-viscosity solution, it becomes easy to form the insulating layer 135 thinly and uniformly.

  Subsequently, as illustrated in FIG. 2E, an EL layer 122 and a conductive layer 123 are formed.

  The EL layer 122 is an organic compound layer and can be formed by a method such as a vapor deposition method, a coating method, a printing method, or a discharge method. In the case where the EL layer 122 is separately formed for each pixel, the EL layer 122 can be formed by an evaporation method using a shadow mask such as a metal mask or an inkjet method. In the case where the EL layer 122 is not formed for each pixel, an evaporation method that does not use a metal mask can be used. Here, an example in which a metal mask is not used for vapor deposition is shown.

  The conductive layer 123 can be formed by an evaporation method, a sputtering method, or the like.

  As described above, the light-emitting element 120 can be formed. The light-emitting element 120 has a structure in which a conductive layer 121 partly functioning as a pixel electrode, an EL layer 122, and a conductive layer 123 partly functioning as a common electrode are stacked.

  Note that an insulating layer functioning as a barrier layer against impurities such as water may be formed so as to cover the conductive layer 123.

  When an inorganic insulating film is used for the insulating layer, for example, a film forming method such as a sputtering method, a plasma CVD method, an ALD method, or an evaporation method can be preferably used. Further, in order to prevent the light emitting element 120 from being damaged when the inorganic insulating film is formed, between the inorganic insulating film and the light emitting element 120, specifically, between the inorganic insulating film and the conductive layer 123, It is preferable to form an organic insulating film. At this time, the organic insulating film may be thin (for example, 100 nm or less), and may be formed using, for example, an evaporation method.

  Through the above steps, the element layer 100 can be formed. At the time shown in FIG. 2E, the element layer 100 is supported by the support substrate 61.

  Next, a method for forming the element layer 200 will be described.

[Formation of resin layer 201]
A support substrate 63 is prepared, and a resin layer 201 is formed over the support substrate 63 (FIG. 3A). The description of the support substrate 61 can be used for the support substrate 63. For the formation method and material of the resin layer 201, the same method as that for the resin layer 101 can be used.

  Note that an insulating layer functioning as a barrier film may be formed over the resin layer 201. The description of the insulating layer 131 can be referred to for a method and a material for forming the insulating layer.

[Formation of Conductive Layer 251, Conductive Layer 221a, Conductive Layer 221c]
Next, a conductive layer 221a and a conductive layer 221c are formed over the conductive layer 251 (FIG. 3B).

  First, after a conductive film is formed, a resist mask is formed, and after the conductive film is etched, the resist mask is removed, whereby the conductive layer 251 is formed. Subsequently, after a conductive film is formed, a resist mask is formed, and after the conductive film is etched, the resist mask is removed, so that the conductive layers 221a and 221c are formed.

[Formation of Insulating Layer 231]
Subsequently, an insulating layer 231 is formed so as to cover the conductive layer 221a, the conductive layer 221c, and the resin layer 201 (FIG. 3C). The description of the insulating layer 131 can be used for a method and a material for forming the insulating layer 231.

[Formation of Transistor 210]
Subsequently, as illustrated in FIG. 3D, the transistor 210 is formed over the insulating layer 231.

  First, the conductive layer 211 is formed over the insulating layer 232, the insulating layer 232 is formed so as to cover the conductive layer 211 and the insulating layer 231, and the semiconductor layer 212 is formed over the insulating layer 232. The conductive layer 211, the insulating layer 232, and the semiconductor layer 212 can be formed by a method similar to that of the conductive layer 111, the insulating layer 132, or the semiconductor layer 112, respectively.

  Subsequently, an opening reaching the conductive layer 221 a is formed in the insulating layer 232 and the insulating layer 231.

  After that, a conductive layer 213a and a conductive layer 213b are formed. The conductive layers 213a and 213b can be formed by a method similar to that of the conductive layers 113a and 113b.

  Here, by forming the conductive layer 113b so as to fill the openings of the insulating layer 231 and the insulating layer 232, the conductive layer 113b and the conductive layer 221a are electrically connected to each other.

  Through the above steps, the transistor 210 can be formed.

  The transistor 210 is a transistor including an oxide semiconductor in the semiconductor layer 212 in which a channel is formed. In the transistor 210, part of the conductive layer 211 functions as a gate, part of the insulating layer 232 functions as a gate insulating layer, and the conductive layers 213a and 213b each function as either a source or a drain. To do.

[Formation of Insulating Layer 233 and Insulating Layer 234]
Next, an insulating layer 233 and an insulating layer 234 are formed in this order so as to cover the transistor 210 (FIG. 3E). The insulating layer 233 and the insulating layer 234 can be formed by a method similar to that of the insulating layer 133 or the insulating layer 134, respectively.

  Next, a light-blocking layer 153 and a colored layer 152 are formed over the insulating layer 234 (FIG. 3F).

  For the light shielding layer 153, for example, a metal material or a resin material can be used. In the case of using a metal material, after forming a conductive film, it can be formed by removing unnecessary portions using a photolithography method or the like. Further, when a photosensitive resin material containing a metal material, a pigment or a dye is used, it can be formed by a photolithography method or the like.

  The coloring layer 152 can be processed into an island shape by a photolithography method or the like by using a photosensitive material.

  At this time, the light-blocking layer 153 has an opening that overlaps with the colored layer 152.

  The light-blocking layer 153 is preferably provided so as to cover the transistor 210. In particular, when a bottom-gate transistor is used as the transistor 210, the light-blocking layer 153 can suppress external light and light from the light-emitting element 120 from reaching the semiconductor layer 212, which can improve reliability. it can.

〔Lamination〕
Subsequently, as illustrated in FIG. 4A, the support substrate 61 and the support substrate 63 are bonded using the adhesive layer 151 so that the element layer 100a and the element layer 100b face each other. Then, the adhesive layer 151 is cured. Thereby, the light emitting element 120 can be sealed with the adhesive layer 151.

  The adhesive layer 151 is preferably made of a curable material. For example, a resin that exhibits photocurability, a resin that exhibits reaction curability, a resin that exhibits thermosetting, or the like can be used. In particular, it is preferable to use a resin material that does not contain a solvent.

  At this time, if the position difference between the support substrate 61 and the support substrate 63 occurs, the light from the light emitting element 120 may be blocked by the light shielding member such as the element layer 100b or the light shielding layer 153. . Therefore, it is preferable that alignment markers are formed on the support substrate 63 and the support substrate 61, respectively.

[Separation of support substrate 61]
4B, the resin layer 101 is irradiated with light 70 from the support substrate 61 side through the support substrate 61. As shown in FIG.

  As the light 70, laser light can be preferably used. In particular, it is preferable to use a linear laser.

  Note that a flash lamp or the like may be used as long as energy equivalent to that of laser light can be irradiated.

  The light 70 preferably uses light having a wavelength that is at least partially transmitted through the support substrate 61 and absorbed by the resin layer 101. In particular, as the wavelength of the light 70, it is preferable to use light in a wavelength region from visible light to ultraviolet light. For example, light having a wavelength of 200 nm to 400 nm, preferably light having a wavelength of 250 nm to 350 nm is preferably used. In particular, it is preferable to use an excimer laser having a wavelength of 308 nm because the productivity is excellent. Since the excimer laser is also used for laser crystallization in LTPS, an existing LTPS production line device can be used, and new equipment investment is not required, which is preferable. Alternatively, a solid-state UV laser (also referred to as a semiconductor UV laser) such as a UV laser having a wavelength of 355 nm, which is the third harmonic of the Nd: YAG laser, may be used. Further, as the laser, a CW (continuous wave) laser or a pulsed laser may be used. As the pulse laser, a short-time pulse laser such as nanosecond, picosecond, or femtosecond, or a pulse laser longer than that (for example, several hundred Hz or less) can be used.

  When linear laser light is used as the light 70, the light 70 is scanned by moving the support substrate 61 and the light source relatively, and the light 70 is irradiated over the region to be peeled off. At this stage, when the entire surface where the resin layer 101 is disposed is irradiated, the entire resin layer 101 can be peeled off, and there is no need to divide the outer peripheral portion of the support substrate 61 by scribe or the like in a subsequent separation step. Alternatively, when a region where the light 70 is not irradiated is provided on the outer periphery of the region where the resin layer 101 is disposed, the region remains highly adhesive. Therefore, the resin layer 101 and the support substrate 61 are Is preferable because it can be prevented from separating.

  By irradiation with light 70, the vicinity of the surface of the resin layer 101 on the side of the support substrate 61 or a part of the inside of the resin layer 101 is modified, the adhesion between the support substrate 61 and the resin layer 101 is lowered, and peeling easily It can be in a possible state.

  Subsequently, the support substrate 61 and the resin layer 101 are separated (FIG. 4C).

  Separation can be performed by applying a pulling force to the support substrate 61 in the vertical direction while the support substrate 63 is fixed to the stage. For example, a part of the upper surface of the support substrate 61 can be adsorbed and pulled upward to be peeled off. The stage may have any configuration as long as the support substrate 63 can be fixed. For example, the stage may have an adsorption mechanism that can perform vacuum adsorption, electrostatic adsorption, or the like, or a mechanism that physically holds the support substrate 63. You may do it. Alternatively, the support substrate 61 may be separated by applying a pulling force to the support substrate 63 in a vertical direction while the support substrate 61 is fixed to the stage.

  The separation may be performed by pressing a drum-like member having adhesiveness on the surface against the upper surface of the support substrate 61 or the support substrate 63 and rotating the member. At this time, the stage may be moved in the peeling direction.

  In addition, in the case where a region where the light 70 is not irradiated is provided on the outer peripheral portion of the resin layer 101, a notch portion may be formed in a part of the portion where the resin layer 101 is irradiated with light to trigger peeling. The notch can be formed, for example, by using a sharp blade or a needle-like member, or by simultaneously cutting the support substrate 61 and the resin layer 101 by scribing.

  Depending on the irradiation condition of the light 70, separation (breakage) may occur inside the resin layer 101, so that a part of the resin layer 101 may remain on the support substrate 61 side. FIG. 4C shows a case where the resin layer 101 is broken inside the resin layer 101 and the resin layer 101a which is a part of the resin layer 101 remains on the support substrate 61 side.

  Alternatively, even when a part of the surface of the resin layer 101 is melted, a part of the resin layer 101 may remain on the support substrate 61 side as well. Note that in the case of peeling at the interface between the support substrate 61 and the resin layer 101, a part of the resin layer 101 may not remain on the support substrate 61 side.

  The thickness of the resin layer 101 remaining on the support substrate 61 side can be set to, for example, 100 nm or less, specifically about 40 nm to 70 nm. The support substrate 61 can be reused by removing the remaining resin layer 101a. For example, when glass is used for the support substrate 61 and polyimide resin is used for the resin layer 101, the remaining resin layer 101a can be removed by ashing, fuming nitric acid, or the like.

[Lamination of substrate 11]
Subsequently, as illustrated in FIG. 5A, the resin layer 101 and the substrate 11 are bonded using the adhesive layer 51.

  The description of the adhesive layer 151 can be used for the adhesive layer 51.

  When a resin material is used as the substrate 11 and the substrate 12 described later, the display device can be reduced in weight as compared with the case where glass or the like is used even if the thickness is the same. In addition, it is preferable to use a material that is thin enough to have flexibility, because the weight can be further reduced. Further, by using a resin material, the impact resistance of the display device can be improved, and a display device that is difficult to break can be realized.

  Moreover, since the board | substrate 11 is a board | substrate located in the opposite side to the visual recognition side, it does not need to have translucency with respect to visible light. Therefore, a metal material can also be used. Since the metal material has high thermal conductivity and can easily conduct heat to the entire substrate, local temperature rise of the display device can be suppressed.

[Separation of support substrate 63]
Subsequently, light 70 is irradiated from the support substrate 63 side to the resin layer 201 through the support substrate 63 (FIG. 5B). About the irradiation method of the light 70, said description can be used.

  Thereafter, as shown in FIG. 5C, the support substrate 63 and the resin layer 201 are separated. FIG. 5C shows an example in which the resin layer 201 is broken inside the resin layer 201 and the resin layer 201a which is a part of the resin layer 201 remains on the support substrate 63 side.

[Thinning of resin layer 201]
Subsequently, a part of the resin layer 201 is removed, and the resin layer 201 is thinned. The thickness of the resin layer 201 after thinning can be made thinner than the resin layer 101, for example. More specifically, for example, it is preferably 1 nm or more and less than 3 μm, preferably 5 nm or more and 1 μm or less, more preferably 10 nm or more and 200 nm or less.

  The thinning may be performed by any method that can etch the resin layer 201, and plasma treatment, dry etching, wet etching, or the like can be used. The dry etching method is particularly preferable because of high uniformity. In addition, since the resin layer 201 contains an organic substance, it is particularly preferable to use plasma treatment (also referred to as ashing treatment) in an atmosphere containing oxygen. In the case of using a wet etching method, it is preferable to perform etching using a diluted etching solution or the like in order to prevent the resin layer 201 from being completely removed. Alternatively, a method may be used in which the material used for forming the thin film to be the resin layer 201 is sufficiently diluted with a solvent to reduce the viscosity, and the thinning of the resin layer 201 is not performed to reduce the thickness.

  FIG. 6A shows a state in which a part of the upper portion of the resin layer 201 is etched and thinned by irradiating the upper surface of the resin layer 201 with plasma 80.

  Although not shown here, it is preferable to fix the substrate 11 side to another support substrate in order to facilitate conveyance in the steps after the substrate 11 is bonded. For example, the substrate 11 and the supporting substrate can be fixed with an adhesive material, a double-sided tape, a silicone sheet, or a water-soluble adhesive. Further, it is preferable that the substrate 11 side is also fixed to another support substrate after the bonding step of the support substrate 64 described later.

  Subsequently, a light-transmitting conductive film is formed over the resin layer 201 and selectively etched to form a conductive layer 221b. The conductive layer 221 may be formed by an inkjet method.

Next, an insulating film covering the conductive layer 221 is formed and selectively etched, so that the insulating layer 244 is formed. In this etching, the resin layer 201 functions as an etching stopper. A cross-sectional view so far corresponds to FIG.

  Subsequently, the resin layer 201 is selectively removed using the insulating layer 244 as a mask.

  Subsequently, the support substrate 64 is prepared. The description of the support substrate 61 can be used for the support substrate 64.

  Subsequently, the light absorption layer 103 is formed on the support substrate 64. The light absorption layer 103 is a layer that releases hydrogen, oxygen, or the like by absorbing the light 70 and generating heat in a subsequent irradiation process of the light 70.

As the light absorption layer 103, for example, a hydrogenated amorphous silicon (a-Si: H) film from which hydrogen is released by heating can be used. The hydrogenated amorphous silicon film can be formed by, for example, a plasma CVD method including SiH ₄ in a film forming gas. Further, in order to further include hydrogen, heat treatment may be performed in an atmosphere containing hydrogen after film formation.

  Alternatively, as the light absorption layer 103, an oxide film from which oxygen is released by heating can be used. In particular, an oxide semiconductor film or an oxide conductor film is preferable because it has a narrower band gap and easily absorbs light than an insulating film such as a silicon oxide film. Note that the oxide conductor film can be formed by increasing the defect level or the impurity level of the oxide semiconductor film. In the case of using an oxide semiconductor, the above-described method for forming the semiconductor layer 112 and materials that can be used for a semiconductor layer described later can be used. The oxide film can be formed by a plasma CVD method, a sputtering method, or the like in an atmosphere containing oxygen, for example. In particular, when an oxide semiconductor film is used, it is preferably formed by a sputtering method in an atmosphere containing oxygen. Further, in order to further include oxygen, heat treatment may be performed in an atmosphere containing oxygen after film formation.

  Alternatively, an oxide insulating film may be used as the oxide film that can be used for the light absorption layer 103. For example, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, a silicon oxynitride film, or the like can be used. For example, such an oxide insulating film is formed at a low temperature (for example, 250 ° C. or lower, preferably 220 ° C. or lower) in an oxygen-containing atmosphere, whereby an oxide insulating film containing excess oxygen is obtained. Can be formed. For film formation, for example, a sputtering method or a plasma CVD method can be used.

  Subsequently, conductive layers 223a, 223b, and 223c are formed over the light absorption layer 103. The conductive layers 223a, 223b, and 223c can be formed using a material that transmits visible light (a light-transmitting conductive film). In the conductive layers 223a, 223b, and 223c, unnecessary portions are removed by etching by a photolithography method or the like after the conductive film is formed.

  Next, an insulating layer is formed over the conductive layers 223a, 223b, and 223c, and selectively etched to form an insulating layer 245 that covers the top surface and side surfaces of the conductive layer 223b (FIG. 7A). The insulating layer 245 is formed in contact with the light absorption layer 103 so as to cover a region where the conductive layers 223a, 223b, and 223c are not formed.

  For the formation method and material of the insulating layer 245, the description of the insulating layer 131 can be used.

[Lamination of substrate 11 and support substrate 64]
Subsequently, as illustrated in FIG. 7B, the substrate 11 and the support substrate 64 are bonded to each other with the dispersion medium 243 interposed therebetween.

  Subsequently, as illustrated in FIG. 7C, the light absorption layer 103 is irradiated with light 70 from the support substrate 64 side through the support substrate 64. About the irradiation method of the light 70, said description can be used.

  Here, light 70 having a wavelength that is at least partially transmitted through the support substrate 61 and absorbed by the light absorption layer 103 is selected and used.

  The light absorption layer 103 is heated by irradiation with the light 70, and hydrogen, oxygen, or the like is released from the light absorption layer 103. The hydrogen or oxygen released at this time is released as a gas. The released gas stays in the vicinity of the interface between the light absorption layer 103 and the resin layer 202 or in the vicinity of the interface between the light absorption layer 103 and the support substrate 64, and a force for peeling them off is generated. As a result, the adhesiveness between the light absorption layer 103 and the resin layer 202 or the adhesiveness between the light absorption layer 103 and the support substrate 64 is lowered, so that it can be easily peeled off.

  In addition, part of the gas released from the light absorption layer 103 may remain in the light absorption layer 103. Therefore, the light absorption layer 103 may become brittle and may be easily separated inside the light absorption layer 103.

  In addition, in the case where a film that releases oxygen is used as the light absorption layer 103, part of the resin layer 202 may be oxidized and embrittled by oxygen released from the light absorption layer 103. Thereby, it can be set in the state which is easy to peel in the interface of the resin layer 202 and the light absorption layer 103. FIG.

  Subsequently, the support substrate 64 and the resin layer 202 are separated (FIG. 8A). The above description can be incorporated. FIG. 8A illustrates an example in which separation occurs at the interface between the conductive layer 223a and the resin layer 202 and the interface between the light absorption layer 103 and the insulating layer 245. Further, in order to improve the adhesion between the resin layer 202 and the substrate 11, a material that can be gelled with high viscosity may be used as the dispersion medium 243, or a polymer network is formed between the conductive layer 223a and the conductive layer 221a. May be.

[Lamination of substrate 12]
Subsequently, the resin layer 202 and the substrate 12 are bonded using the adhesive layer 52 (FIG. 8B). For the adhesive layer 52, the description of the adhesive layer 151 can be used.

  Since the board | substrate 12 is a board | substrate located in the visual recognition side, the material which has translucency with respect to visible light can be used. Further, instead of the substrate 12, a liquid material may be applied by a spray device and then cured to form a substrate. In this case, the adhesive layer 52 can be dispensed with.

As shown in FIG. 8B, two types of charged particles are randomly arranged in the dispersion medium 243 immediately after the production. By applying a voltage to the dispersion medium 243 from this state, it is moved to the vicinity of the conductive layer surface. If voltage is applied to the dispersion medium 243 even once, the charged particle group moves, and the cross-sectional structure shown in FIG. 1A or 1B can be obtained.

  Through the above steps, the display device 10 illustrated in FIG. 1 can be manufactured.

In the figure, the shape of the cross section of the charged particle is illustrated as a circle, but the shape is not particularly limited, and the cross sectional shape may be an ellipse, a rectangle, or a needle shape.

In addition, the display device 10 illustrated in FIGS. 1A and 1B can display in a display region by applying an electric field between the conductive layer 223a and the conductive layer 221a or by controlling a sequence of applying the electric field. Information can be entered, erased, and rewritten. For example, when a positive voltage is applied to the conductive layer 223b, white display charged particles having negative chargeability are collected, and external light is reflected to produce a white display as shown in FIG. Further, when a negative voltage is applied to the conductive layer 223b, black display charged particles having a positive chargeability gather and absorb external light. When a ground potential (0 V) is applied to both the conductive layer 223b and the conductive layer 221b, a positive voltage is applied to the conductive layer 223a, and a negative voltage is applied to the conductive layer 221b, the charged particle groups are It moves and the area | region 31 can be made into a translucent area | region as shown to FIG. 1 (B).

Further, although an example in which an organic EL element is used as the light-emitting element 120 is described in this embodiment mode, the present invention is not particularly limited, and an LED, a QLED (Quantum-Dot Light Emitting Diode), a semiconductor laser, or the like may be used.

(Embodiment 2)
In this embodiment, a display module and an electronic device each including the display device of one embodiment of the present invention will be described with reference to FIGS.

  A display module 8000 illustrated in FIG. 9 includes a touch panel 8004 to which an FPC 8003 is connected, a display panel 8006 to which an FPC 8005 is connected, a frame 8009, a printed board 8010, and a battery 8011 between an upper cover 8001 and a lower cover 8002.

  The display device of one embodiment of the present invention can be used for the display panel 8006, for example.

  The shapes and dimensions of the upper cover 8001 and the lower cover 8002 can be changed as appropriate in accordance with the sizes of the touch panel 8004 and the display panel 8006.

  As the touch panel 8004, a resistive touch panel or a capacitive touch panel can be used by being superimposed on the display panel 8006. In addition, the counter substrate (sealing substrate) of the display panel 8006 can have a touch panel function. In addition, an optical sensor can be provided in each pixel of the display panel 8006 to provide an optical touch panel.

  The frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed board 8010 in addition to a protective function of the display panel 8006. The frame 8009 may have a function as a heat sink.

  The printed board 8010 includes a power supply circuit, a signal processing circuit for outputting a video signal and a clock signal. As a power supply for supplying power to the power supply circuit, an external commercial power supply may be used, or a power supply using a battery 8011 provided separately may be used. The battery 8011 can be omitted when a commercial power source is used.

  The display module 8000 may be additionally provided with a member such as a polarizing plate, a retardation plate, or a prism sheet.

  10A to 10E and FIGS. 11A to 11E illustrate electronic devices. These electronic devices include a housing 9000, a display portion 9001, a camera 9002, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, and a sensor 9007 (force, displacement, position, speed, acceleration). , Angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, smell or infrared A microphone 9008 and the like.

  The electronic devices illustrated in FIGS. 10A to 10E and FIGS. 11A to 11E can have a variety of functions. For example, a function for displaying various information (still images, moving images, text images, etc.) on the display unit, a touch panel function, a function for displaying a calendar, date or time, a function for controlling processing by various software (programs), Wireless communication function, function for connecting to various computer networks using the wireless communication function, function for transmitting or receiving various data using the wireless communication function, and reading and displaying the program or data recorded on the recording medium It can have a function of displaying on the section. Note that the functions of the electronic devices illustrated in FIGS. 10A to 10E and FIGS. 11A to 11E are not limited to these, and may have other functions. .

  Details of the electronic devices illustrated in FIGS. 10A to 10E and FIGS. 11A to 11E are described below.

  FIG. 10A is a perspective view illustrating a television device 9100. FIG. The television device 9100 can incorporate a display portion 9001 with a large screen, for example, a display portion 9001 with a size of 50 inches or more, 80 inches or more, or 100 inches or more.

  10B shows a portable information terminal 9101, FIG. 10C shows a portable information terminal 9102, FIG. 10D shows a portable information terminal 9103, and FIG. 10E shows a portable information terminal 9104. It is a perspective view.

  A portable information terminal 9101 illustrated in FIG. 10B has one or a plurality of functions selected from, for example, a telephone, a notebook, an information browsing device, or the like. Specifically, it can be used as a smartphone. Although not illustrated, the portable information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. Further, the portable information terminal 9101 can display characters and image information on the plurality of surfaces. For example, three operation buttons 9050 (also referred to as operation icons or simply icons) can be displayed on one surface of the display portion 9001. Further, information 9051 indicated by a broken-line rectangle can be displayed on another surface (for example, a side surface) of the display portion 9001. As an example of the information 9051, a display for notifying an incoming call such as an e-mail, SNS (social networking service), a telephone call, a title such as an e-mail or SNS, a sender name such as an e-mail or SNS, a date and time, and a time , Battery level, received signal strength, etc. Alternatively, an operation button 9050 or the like may be displayed instead of the information 9051 at a position where the information 9051 is displayed. In addition, the display portion 9001 included in the portable information terminal 9101 has a curved surface in part.

  A portable information terminal 9102 illustrated in FIG. 10C has a function of displaying information on three or more surfaces of the display portion 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different planes. For example, the user of the portable information terminal 9102 can check the display (information 9053 here) in a state where the portable information terminal 9102 is stored in the chest pocket of clothes. Specifically, the telephone number or name of the caller of the incoming call is displayed at a position where it can be observed from above portable information terminal 9102. The user can check the display and determine whether to receive a call without taking out the portable information terminal 9102 from the pocket. In addition, the display portion 9001 included in the portable information terminal 9102 has a curved surface in part.

  A portable information terminal 9103 illustrated in FIG. 10D is different from the above-described portable information terminals 9101 and 9102 in that the display portion 9001 does not have a curved surface.

  Further, in the portable information terminal 9104 illustrated in FIG. 10E, the display portion 9001 is curved. As shown in FIG. 10E, a camera 9002 is provided in the portable information terminal 9104 so that a still image capturing function, a moving image capturing function, and a captured image are stored in a recording medium (externally or built in the camera). It is preferable to have a function of saving, a function of displaying captured images on the display portion 9001, and the like.

  11A is a perspective view illustrating a wristwatch-type portable information terminal 9200, and FIG. 11B is a perspective view illustrating a wristwatch-type portable information terminal 9201.

  A portable information terminal 9200 illustrated in FIG. 11A can execute various applications such as a mobile phone, electronic mail, text browsing and creation, music playback, Internet communication, and computer games. Further, the display portion 9001 is provided with a curved display surface, and can perform display along the curved display surface. In addition, the portable information terminal 9200 can execute short-range wireless communication with a communication standard. For example, it is possible to talk hands-free by communicating with a headset capable of wireless communication. In addition, the portable information terminal 9200 includes a connection terminal 9006 and can directly exchange data with other information terminals via a connector. Charging can also be performed through the connection terminal 9006. Note that the charging operation may be performed by wireless power feeding without using the connection terminal 9006.

  In addition, the portable information terminal 9201 illustrated in FIG. 11B is different from the portable information terminal illustrated in FIG. 11A in that the display surface of the display portion 9001 is not curved. Further, the external shape of the display portion of the portable information terminal 9201 is a non-rectangular shape (a circular shape in FIG. 11B).

  11C, 11D, and 11E are perspective views illustrating a foldable portable information terminal 9202. FIG. Note that FIG. 11C is a perspective view of a state in which the portable information terminal 9202 is expanded, and FIG. 11D is a state in which the portable information terminal 9202 is expanded or changed from one of the folded state to the other. FIG. 11E is a perspective view of the portable information terminal 9202 folded.

  The portable information terminal 9202 is excellent in portability in the folded state, and in the expanded state, the portable information terminal 9202 is excellent in display listability due to a seamless wide display area. A display portion 9001 included in the portable information terminal 9202 is supported by three housings 9000 connected by a hinge 9055. By bending between the two housings 9000 via the hinge 9055, the portable information terminal 9202 can be reversibly deformed from the expanded state to the folded state. For example, the portable information terminal 9202 can be bent with a curvature radius of 1 mm to 150 mm.

In the portable information terminal, the power consumption of the standby screen in a standby state in which the display screen is not used with the main power turned on contributes to battery consumption, which is a problem. Further, the display on the standby screen may lead to screen burn-in or deterioration of the display element. In a conventional portable information terminal, a liquid crystal backlight or an organic EL element emits a part of light. By adopting the configuration of the present embodiment, if the standby screen is maintained in the electrophoretic display mode to maintain a still image, it is possible to take advantage of a memory function that does not erase characters even if there is no power supply. . Further, when it is desired to display a clock or the like immediately from the standby screen, the time can be instantly recognized by switching to the display using the organic EL element. In this case, the electrophoretic display mode and the self-luminous display mode using the organic EL element can be simultaneously driven in the same display area, and a still screen and a clock display can be simultaneously performed, resulting in a combined image.

A screen combining a static screen and a number display may be difficult to see compared to a display with only a number display, but it can be stored as an image compared to storing only numbers, so it is remembered for human memory. There is also an effect that it becomes easy.

  Note that the display device which is one embodiment of the present invention can be favorably used for the display portion 9001.

  The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

DESCRIPTION OF SYMBOLS 10 Display apparatus 11 Board | substrate 12 Board | substrate 21 Light emission 22a Reflected light 22b Reflected light 31 Area | region 51 Adhesive layer 52 Adhesive layer 61 Support substrate 63 Support substrate 64 Support substrate 70 Light 80 Plasma 100 Element layer 100a Element layer 100b Element layer 101 Resin layer 101a Resin Layer 103 light absorption layer 110 transistor 111 conductive layer 112 semiconductor layer 113a conductive layer 113b conductive layer 120 light emitting element 121 conductive layer 122 EL layer 123 conductive layer 131 insulating layer 132 insulating layer 133 insulating layer 134 insulating layer 135 insulating layer 151 adhesive layer 152 Colored layer 153 Light shielding layer 200 Element layer 200a Element layer 201 Resin layer 201a Resin layer 202 Resin layer 210 Transistor 211 Conductive layer 212 Semiconductor layer 213a Conductive layer 213b Conductive layer 221a Conductive layer 221b Conductive layer 221c Conductive layer 2 3a conductive layer 223b conductive layer 223c conductive layer 231 insulating layer 232 insulating layer 233 insulating layer 234 insulating layer 240 display device 241 charged particles 242 charged particles 243 dispersion medium 244 insulating layer 245 insulating layer 251 conductive layer

Claims (6)

A first electrode having translucency;
A second electrode having translucency;
A third electrode made of the same material as the second electrode;
A dispersion medium having translucency;
A plurality of types of positively or negatively charged particles,
Having a light emitting element,
The dispersion medium and the particle group are disposed between the first electrode and the second electrode,
The light emitting element overlaps the first electrode and the second electrode;
The transmittance between the first electrode and the second electrode is changed by the voltage applied to one or more of the first electrode, the second electrode, or the third electrode,
The light from the light-emitting element is a display device that passes through the first electrode, the second electrode, and the dispersion medium. 2. The display device according to claim 1, wherein the particle group is moved by a voltage applied to the first electrode, the second electrode, or the third electrode. 3. The light-emitting element according to claim 1, wherein the light-emitting element includes a fourth electrode that overlaps the second electrode, a fifth electrode that overlaps the fourth electrode, the fourth electrode, and the fifth electrode. A display device which is an organic light-emitting element having an organic compound layer between electrodes. 4. The display device according to claim 1, wherein the plurality of types of particle groups includes charged particles for black display and charged particles for white display. 5. The display device according to claim 1, wherein the plurality of types of particle groups include at least charged particles for red display, charged particles for green display, and charged particles for blue display.   The display device according to claim 1, comprising at least charged particles for yellow display, charged particles for magenta color display, and charged particles for cyan color display.

Images